Performance of ductless personalized ventilation in conjunction with displacement ventilation

DEFF Research Database (Denmark)

Dalewski, Mariusz; Melikov, Arsen Krikor; Vesely, Michal

2014-01-01

perception of the environment. The subjects could control the position of the DPV supply diffuser and the personalized air flow (air velocity). The use of DPV improved perceived air quality and thermal comfort compared to displacement ventilation alone. At 26 °C and 29 °C the percentage dissatisfied with air......, increased eye dryness sensation was reported by 30% of subjects. The personalized air flow selected by nearly 80% of the subjects at 26 °C was between 10 and 20 l/s corresponding to the target air velocity of 1.2–1.7 m/s. At 29 °C almost 90% of subjects chose a personalized air flow between 15 and 20 l/s (1...

Co-occupant's exposure to exhaled pollutants with two types of personalized ventilation strategies under mixing and displacement ventilation systems.

Science.gov (United States)

Li, X; Niu, J; Gao, N

2013-04-01

Personalized ventilation (PV) system in conjunction with total ventilation system can provide cleaner inhaled air for the user. Concerns still exist about whether the normally protecting PV device, on the other hand, facilitates the dispersion of infectious agents generated by its user. In this article, two types of PV systems with upward supplied fresh air, namely a chair-based PV and one kind of desk-mounted PV systems, when combined with mixing ventilation (MV) and displacement ventilation (DV) systems, are investigated using simulation method with regard to their impacts on co-occupant's exposure to the exhaled droplet nuclei generated by the infected PV user. Simulation results of tracer gas and particles with aerodynamic diameter of 1, 5, and 10 μm from exhaled air show that, when only the infected person uses a PV, the different PV air supplying directions present very different impacts on the co-occupant's intake under DV, while no apparent differences can be observed under MV. The findings demonstrate that better inhaled air quality can always be achieved under DV when the adopted PV system can deliver conditioned fresh air in the same direction with the mainly upward airflow patterns of DV. © 2012 John Wiley & Sons A/S. Published by Blackwell Publishing Ltd.

Respiratory alkalosis and associated electrolytes in long-term ventilator dependent persons with tetraplegia.

Science.gov (United States)

Watt, J W; Silva, P

2001-11-01

A pilot case control study of the acid-base and electrolyte status in 30 long-term ventilator-dependent (LTVD) and 30 self ventilating persons with tetraplegia. To assess the extent of respiratory alkalosis and screen for associated hypokalaemia, hypomagnesaemia and/or hypophosphataemia. Medically stable persons with tetraplegia under the long-term care of the Southport Spinal Injuries Centre, England. Blood gases and electrolytes were sampled from 30 control patients with tetraplegia and from 30 patients having been LTVD for more than 12 months. All the blood gas measurements in the LTVD group lay outside both the reference range and the 95% confidence intervals (CI) of the control group: pH 7.46 (0.06); PCO(2) 3.46 (1.1) kPa; bicarbonate 18.3 (3.8) and base excess -3.2 (2.8) mmol/l; PO(2) 13.8 (2.8) kPa (means and standard deviations). The serum potassium, magnesium, phosphate, and sodium means lay within the reference ranges but the potassium, phosphate and calcium were at or below the 95% CI of the control values. One patient on part-time ventilatory support having less bicarbonate compensation had low serum electrolytes during ventilation. There was no evidence of biochemical jeopardy from long-term mechanical hyperventilation although acutely administered hyperventilation has the potential to cause falls in serum potassium, magnesium and phosphate and so caution should be exercised in part-time ventilated persons. The full range of electrolytes should be assayed during stabilisation in LTVD and periodically thereafter. Hyperventilation helps to maintain good oxygenation in LTVD persons with paralysis and normal lungs. None.

Improving comfort and health with personalized ventilation

DEFF Research Database (Denmark)

Melikov, Arsen Krikor

2004-01-01

The thermal environment and air quality in buildings affects occupants¿ health, comfort and performance. The heating, ventilating and air-conditioning (HVAC) of buildings today is designed to provide a uniform room environment. However, large individual differences exist between occupants in regard...... existing knowledge on performance of personalized ventilation (PV) and on human response to it. The airflow interaction in the vicinity of the human body is analysed and its impact on thermal comfort and inhaled air quality is discussed together with control strategies and the application of PV in practice...

Experimental study on human exposure to occupant generated pollutants in rooms with ductless personalized ventilation

DEFF Research Database (Denmark)

Melikov, Arsen Krikor; Bolashikov, Zhecho Dimitrov; Lu, Pengfei

2014-01-01

The performance of “ductless” personalized ventilation in conjunction with displacement ventilation with regard to exposure to different body bioeffluents was studied. Experiments were performed in a full-scale room furnished as a double office. Room air temperature was kept at 26 oC. Two breathing...... modes for the ductless personalized and displacement ventilation were tested. The location of the bioeffluent source affected the spread of body bioeffluents in the space. The ductless personalized ventilation provided cleaner air to both occupants than displacement ventilation alone. Occupants using...... the ”ductless” system will perceive the supplied air quality as superior compared to displacement ventilation alone....

Energy-saving strategies with personalized ventilation in cold climates

DEFF Research Database (Denmark)

Shiavon, Stefano; Melikov, Arsen Krikor

2009-01-01

In this study the influence of the personalized supply air temperature control strategy on energy consumption and the energy-saving potentials of a personalized ventilation system have been investigated by means of simulations with IDA-ICE software. GenOpt software was used to determine the optimal...

Performance of personalized ventilation combined with chilled ceiling in an office room: inhaled air quality and contaminant distribution

DEFF Research Database (Denmark)

Lipczynska, Aleksandra; Kaczmarczyk, Jan; Melikov, Arsen Krikor

2014-01-01

people (exhaled air, bioeffluents) and building materials (wall painting). Personalized ventilation combined with chilled ceiling ensured highest air quality at the workstation under all conditions. Pollutant concentration in the occupied zone away from the workstations did not differ substantially...... between the tested systems. Chilled ceiling combined with personalized ventilation working as the only air supplying system may be optimal solution in many buildings.......In a simulated two persons’ office room inhaled air quality and contaminant distribution provided with personalized ventilation combined with chilled ceiling, mixing ventilation only, chilled ceiling with mixing ventilation and chilled ceiling with mixing and personalized ventilation was studied...

Distribution of contaminants in the occupied zone of a room with personalized and displacement ventilation

DEFF Research Database (Denmark)

Cermak, Radim; Melikov, Arsen Krikor; Forejt, L.

2004-01-01

A distribution of contaminants from floor covering, exhaled air and human bioeffluents was examined in a mock-up of a typical two-person office by means of tracer-gases. The distribution was studied with two types of air terminal device for personalized ventilation combined with displacement...... ventilation. The results document that the distribution of contaminants depends to a great extent on the type and operation of personalized ventilation, as well as on the type and location of contaminant sources....

Protection of occupants from exhaled infectious agents and floor material emissions in rooms with personalized and underfloor ventilation

DEFF Research Database (Denmark)

Cermak, Radim; Melikov, Arsen Krikor

2007-01-01

the concentration of exhaled air pollution increased in the room. The two types of personalized ventilation performed differently. Subsequent analyses of airborne infection transmission risk indicated that personalized ventilation could become a supplement to traditional methods of infection control....... of pollutants associated with exhaled air and floor material emissions was evaluated at various combinations of personalized and underfloor airflow rates. Compared to underfloor ventilation alone, personalized and underfloor ventilation provided excellent protection Of seated occupants from any pollution, while......The performance of two personalized. ventilation systems supplying air at the breathing zone was tested in conjunction with underfloor ventilation generating two different airflow patterns in a full-scale test room. Two breathing thermal manikins were used to simulate occupants. The distribution...

Inhaled air quality with desk incorporated personalized ventilation (PV): parametric study

DEFF Research Database (Denmark)

Bolashikov, Zhecho Dimitrov; Nagano, Hideaki; Melikov, Arsen Krikor

A workstation consisting of a desk with installed personalized ventilation (PV) and a dressed breathing thermal manikin simulating seated occupant was set in a full-scale test room. The room was conditioned by overhead ventilation at 26 oC. The PV consisted of two confluent jets incorporated along...

Experimental investigation of reduced-mixing personal ventilation jets

Energy Technology Data Exchange (ETDEWEB)

Khalifa, H. Ezzat; Janos, Michael I.; Dannenhoffer, John F. III. [Syracuse University, Syracuse, NY (United States)

2009-08-15

This paper presents an investigation of the design and performance characteristics of personalized ventilation (PV) systems that, in combination with general ventilation, deliver high quality air to the breathing zone (BZ) with no more clean air supply than indicated by ANSI/ASHRAE 62.1-2004, while satisfying acceptable ergonomic and aesthetic considerations. Under these conditions, the energy used for conditioning the clean air will not exceed that of a conventional ventilation system. We introduce a novel PV nozzle that achieves high BZ air quality with a small fraction of the clean air indicated by the ANSI/ASHRAE Standard. Tracer gas experimental results presented in this paper demonstrate the advantages of the novel nozzle relative to conventional PV nozzles. The results show that, at a PV clean air supply of only 2.4 l/s, the new nozzle achieves a BZ ventilation effectiveness close to 7 versus less than 2 for a conventional nozzle delivering the same amount of clean air. A companion paper presents a computational analysis of the same concept, validated against the experimental results of the present paper. (author)

Seat headrest-incorporated personalized ventilation: Thermal comfort and inhaled air quality

DEFF Research Database (Denmark)

Melikov, Arsen Krikor; Ivanova, T.; Stefanova, G.

2012-01-01

inhaled by the manikin was measured and used to assess the clean air supply efficiency of the SHPV. The response of 35 subjects was collected to examine thermal comfort with the SHPV. The subjects participated in 3 experiments at personalized air temperature and room air temperature of 22/20 °C, 23/23 °C......The performance of personalized ventilation with seat headrest-mounted air supply terminal devices (ATD), named seat headrest personalized ventilation (SHPV), was studied. Physical measurements using a breathing thermal manikin were taken to identify its ability to provide clean air to inhalation...... depending on design, shape, size and positioning of the ATD, flow rate and temperature of personalized air, room temperature, clothing thermal insulation of the manikin, etc. Tracer gas was mixed with the room air. The air supplied by the SHPV was free of tracer gas. Tracer gas concentration in the air...

Design of Mine Ventilators Monitoring System Based on Wireless Sensor Network

International Nuclear Information System (INIS)

Fu Sheng; Song Haiqiang

2012-01-01

A monitoring system for a mine ventilator is designed based on ZigBee wireless sensor network technology in the paper. The system consists of a sink node, sensor nodes, industrial personal computer and several sensors. Sensor nodes communicate with the sink node through the ZigBee wireless sensor network. The sink node connects with the configuration software on the pc via serial port. The system can collect or calculate vibration, temperature, negative pressure, air volume and other information of the mine ventilator. Meanwhile the system accurately monitors operating condition of the ventilator through these parameters. Especially it provides the most original information for potential faults of the ventilator. Therefore, there is no doubt that it improves the efficiency of fault diagnosis.

Design of Mine Ventilators Monitoring System Based on Wireless Sensor Network

Science.gov (United States)

Fu, Sheng; Song, Haiqiang

2012-05-01

A monitoring system for a mine ventilator is designed based on ZigBee wireless sensor network technology in the paper. The system consists of a sink node, sensor nodes, industrial personal computer and several sensors. Sensor nodes communicate with the sink node through the ZigBee wireless sensor network. The sink node connects with the configuration software on the pc via serial port. The system can collect or calculate vibration, temperature, negative pressure, air volume and other information of the mine ventilator. Meanwhile the system accurately monitors operating condition of the ventilator through these parameters. Especially it provides the most original information for potential faults of the ventilator. Therefore, there is no doubt that it improves the efficiency of fault diagnosis.

Human Response to Personalized Ventilation Combined with Chilled Ceiling

DEFF Research Database (Denmark)

Lipczynska, Aleksandra; Kaczmarczyk, Jan; Marcol, Bartosz

2014-01-01

Personalized ventilation (PV) improves inhaled air quality, because it provides fresh air to each workstation and directly to occupant’s breathing zone. Previous research was focused on combining PV with additional total volume air distribution, i.e. mixing ventilation or displacement ventilation......, the use of radiant ceiling cooling will provide operative temperature lower than the air temperature and will improve further occupants’ thermal comfort at warm environment. Therefore combining PV with chilled ceiling may be an effective way to provide thermal comfort in rooms at temperature higher than...... temperature for chilled ceiling was 15,5/16,8°C at room air temperature of 26°C and 19,5/20,6°C at 28°C. During the experiment the subjects were performing typical office tasks at workstations with computers. Exposure included also increased activity level office work for a period of 25 min...

Performance of personalized ventilation in a room with an underfloor air distribution system: transport of contaminants between occupants

DEFF Research Database (Denmark)

Cermak, Radim; Melikov, Arsen Krikor

2003-01-01

the workplaces has not been studied in detail. This paper presents a study on the performance of a personalized ventilation system installed in a full-scale test room with an underfloor air distribution system. Transport of human-produced airborne pollutants (in real life they can be infectious agents) between......Studies have documented that personalized ventilation, which provides clean air at each office workplace, is able to improve substantially the quality of air inhaled by occupants. However, the interaction between the airflow generated by personalized ventilation and the airflow pattern outside...... two occupants was examined using a tracer-gas. Two breathing thermal manikins were used to simulate occupants. The results show that the tested combination of personalized and underfloor ventilation was not able to decrease concentration of the human-produced airborne pollutants in air inhaled...

Personalized ventilation: evaluation of different air terminal devices

DEFF Research Database (Denmark)

Melikov, Arsen Krikor; Cermak, Radim; Majer, M.

2002-01-01

Personalized ventilation (PV) aims to provide clean air to the breathing zone of occupants. Its performance depends to a large extent on the supply air terminal device (ATD). Five different ATDs were developed, tested and compared. A typical office workplace consisting of a desk with mounted ATDs...... was simulated in a climate chamber. A breathing thermal manikin was used to simulate a human being. Experiments at room air temperatures of 26 and 20 deg.C and personalized air temperatures of 20 deg.C supplied from the ATDs were performed. The flow rate of personalized air was changed from less than 5 up to 23...... l/s. Tracer gas was used to identify the amount of personalized air inhaled by the manikin as well as the amount of exhaled air re-inhaled. The heat loss from the body segments of the thermal manikin was measured and used to calculate the equivalent temperature for the whole body as well as segments...

Impact of airflow interaction on inhaled air quality and transport of contaminants in rooms with personalized and total volume ventilation

DEFF Research Database (Denmark)

Melikov, Arsen Krikor; Cermak, Radim; Kovar, O.

2003-01-01

The impact of airflow interaction on inhaled air quality and transport of contaminants between occupants was studied in regard to pollution from floor covering, human bioeffluents and exhaled air, with combinations of two personalized ventilation systems (PV) with mixing and displacement...... quality with personalized and mixing ventilation was higher or at least similar compared to mixing ventilation alone. In the case of PV combined with displacement ventilation, the interaction caused mixing of the room air, an increase in the transport of bioeffluents and exhaled air between occupants and...... ventilation. In total, 80 L/s of clean air supplied at 20°C was distributed between the ventilation systems at different combinations of personalized airflow rate. Two breathing thermal manikins were used to simulate occupants in a full-scale test room. Regardless of the airflow interaction, the inhaled air...

Improved Performance of Personalized Ventilation by Control of the Convection Flow around Occupant Body

DEFF Research Database (Denmark)

Bolashikov, Zhecho Dimitrov; Melikov, Arsen Krikor; Krenek, Miroslav

2009-01-01

This paper reports on methods of control of the free convection flow around human body aiming at improvement of inhaled air quality for occupants at workstations with personalized ventilation (PV). Two methods of control were developed and explored: passive - blocking the free convection developm......This paper reports on methods of control of the free convection flow around human body aiming at improvement of inhaled air quality for occupants at workstations with personalized ventilation (PV). Two methods of control were developed and explored: passive - blocking the free convection......-scale test room with background mixing ventilation. Thermal manikin with realistic free convection flow was used. The PV supplied air from front/above towards the face. All measurements were performed under isothermal conditions at 20 °C and 26 °C. The air in the test room was mixed with tracer gas, while...

Impact of personalized ventilation combined with chilled ceiling on eye irritation symptoms

DEFF Research Database (Denmark)

Lipczynska, Aleksandra; Marcol, Bartosz; Kaczmarczyk, Jan

2014-01-01

Personalized ventilation (PV) improves inhaled air quality, because it provides fresh air to each workstation and directly to occupant’s breathing zone. The PV alone can be used for room ventilation when applied in conjunction with ceiling radiant cooling system, which removes sensible heat loads...... from the space. Combining PV with chilled ceiling may be an effective way to provide thermal comfort in rooms at air temperature higher than the recommended in the standards upper limit of 26°C (category II), because the operative temperature will be lower. However, combination of high air temperature...

Sensor-based demand controlled ventilation

Energy Technology Data Exchange (ETDEWEB)

De Almeida, A.T. [Universidade de Coimbra (Portugal). Dep. Eng. Electrotecnica; Fisk, W.J. [Lawrence Berkeley National Lab., CA (United States)

1997-07-01

In most buildings, occupancy and indoor pollutant emission rates vary with time. With sensor-based demand-controlled ventilation (SBDCV), the rate of ventilation (i.e., rate of outside air supply) also varies with time to compensate for the changes in pollutant generation. In other words, SBDCV involves the application of sensing, feedback and control to modulate ventilation. Compared to ventilation without feedback, SBDCV offers two potential advantages: (1) better control of indoor pollutant concentrations; and (2) lower energy use and peak energy demand. SBDCV has the potential to improve indoor air quality by increasing the rate of ventilation when indoor pollutant generation rates are high and occupants are present. SBDCV can also save energy by decreasing the rate of ventilation when indoor pollutant generation rates are low or occupants are absent. After providing background information on indoor air quality and ventilation, this report provides a relatively comprehensive discussion of SBDCV. Topics covered in the report include basic principles of SBDCV, sensor technologies, technologies for controlling air flow rates, case studies of SBDCV, application of SBDCV to laboratory buildings, and research needs. SBDCV appears to be an increasingly attractive technology option. Based on the review of literature and theoretical considerations, the application of SBDCV has the potential to be cost-effective in applications with the following characteristics: (a) a single or small number of dominant pollutants, so that ventilation sufficient to control the concentration of the dominant pollutants provides effective control of all other pollutants; (b) large buildings or rooms with unpredictable temporally variable occupancy or pollutant emission; and (c) climates with high heating or cooling loads or locations with expensive energy.

Thermal environment and air quality in office with personalized ventilation combined with chilled ceiling

DEFF Research Database (Denmark)

Lipczynska, Aleksandra; Kaczmarczyk, Jan; Melikov, Arsen Krikor

2015-01-01

The thermal environment and air quality conditions provided with combined system of chilled ceiling and personalized ventilation (PV) were studied in a simulated office room for two occupants. The proposed system was compared with total volume HVAC solutions used today, namely mixing ventilation...... and chilled ceiling combined with mixing ventilation. The objective of the study was to evaluate whether PV can be the only ventilation system in the rooms equipped with chilled ceiling. The room air temperature was 26°C in cases with traditional systems and 28°C when PV was used. PV supplied air...... with the temperature of 25°C. PV improved thermal conditions and was up to nearly 10 times more efficient in delivering clean air at workstations than mixing ventilation systems, which resulted in strong protection of occupants from the cross-infection. In the room space outside workstations no substantial differences...

Airflow characteristics in the breathing zone of a seated person using desk incorporated pair of confluent jets as personalized ventilation - effect of supply velocities

DEFF Research Database (Denmark)

Bolashikov, Zhecho Dimitrov; Nagano, Hideaki; Melikov, Arsen Krikor

A workplace with desk, desk incorporated personalized ventilation (PV) and a dressed thermal manikin with realistic body and surface temperature distribution were set in a test room (4.70 m x 1.62 m x 2.6 m). 15 L/s were supplied from a ceiling diffuser to ventilate the room at 26 oC air temperat......A workplace with desk, desk incorporated personalized ventilation (PV) and a dressed thermal manikin with realistic body and surface temperature distribution were set in a test room (4.70 m x 1.62 m x 2.6 m). 15 L/s were supplied from a ceiling diffuser to ventilate the room at 26 oC air...... and upwards from the inner jet (closest to manikin) was the same, twice bigger or twice lower compared to that of the outer jet. The mean velocity field at the breathing zone was measured by Particle Image Velocimetry: a dual cavity laser (λ = 532 nm) and a CCD camera - 35 mm lenses. Glycerol droplets...

Potential energy savings with personalized ventilation coupled with passive chilled beams

DEFF Research Database (Denmark)

Lyubenova, Velina S.; Holsøe, Jan W.; Melikov, Arsen Krikor

2011-01-01

Personalized ventilation (PV) is an individually controlled air distribution system aimed at improving inhaled air quality and thermal comfort of each occupant. Numerous studies have shown that PV may improve occupants’ health, comfort and performance in comparison with traditional total volume air...... saving especially in spaces where occupants spend most of the time at their workplace....

A bench study of intensive-care-unit ventilators: new versus old and turbine-based versus compressed gas-based ventilators

Science.gov (United States)

Thille, Arnaud W.; Lyazidi, Aissam; Richard, Jean-Christophe M.; Galia, Fabrice; Brochard, Laurent

2009-01-01

Objective To compare 13 commercially available, new-generation, intensive-care-unit (ICU) ventilators regarding trigger function, pressurization capacity during pressure-support ventilation (PSV), accuracy of pressure measurements and expiratory resistance. Design and Setting Bench study at a research laboratory in a university hospital. Material Four turbine-based ventilators and nine conventional servo-valve compressed-gas ventilators were tested using a two-compartment lung model. Results Three levels of effort were simulated. Each ventilator was evaluated at four PSV levels (5, 10, 15, and 20 cm H2O), with and without positive end-expiratory pressure (5 cm H2O, Trigger function was assessed as the time from effort onset to detectable pressurization. Pressurization capacity was evaluated using the airway pressure-time product computed as the net area under the pressure-time curve over the first 0.3 s after inspiratory effort onset. Expiratory resistance was evaluated by measuring trapped volume in controlled ventilation. Significant differences were found across the ventilators, with a range of triggering-delay from 42 ms to 88 ms for all conditions averaged (Pventilators at PSV5 and three at PSV10, suggesting an inability to unload patient’s effort. On average, turbine-based ventilators performed better than conventional ventilators, which showed no improvement compared to a 2000 bench comparison. Conclusion Technical performances of trigger function, pressurization capacity and expiratory resistance vary considerably across new-generation ICU ventilators. ICU ventilators seem to have reached a technical ceiling in recent years, and some ventilators still perform inadequately. PMID:19352622

Model-based setting of inspiratory pressure and respiratory rate in pressure-controlled ventilation

International Nuclear Information System (INIS)

Schranz, C; Möller, K; Becher, T; Schädler, D; Weiler, N

2014-01-01

Mechanical ventilation carries the risk of ventilator-induced-lung-injury (VILI). To minimize the risk of VILI, ventilator settings should be adapted to the individual patient properties. Mathematical models of respiratory mechanics are able to capture the individual physiological condition and can be used to derive personalized ventilator settings. This paper presents model-based calculations of inspiration pressure (p I ), inspiration and expiration time (t I , t E ) in pressure-controlled ventilation (PCV) and a retrospective evaluation of its results in a group of mechanically ventilated patients. Incorporating the identified first order model of respiratory mechanics in the basic equation of alveolar ventilation yielded a nonlinear relation between ventilation parameters during PCV. Given this patient-specific relation, optimized settings in terms of minimal p I and adequate t E can be obtained. We then retrospectively analyzed data from 16 ICU patients with mixed pathologies, whose ventilation had been previously optimized by ICU physicians with the goal of minimization of inspiration pressure, and compared the algorithm's ‘optimized’ settings to the settings that had been chosen by the physicians. The presented algorithm visualizes the patient-specific relations between inspiration pressure and inspiration time. The algorithm's calculated results highly correlate to the physician's ventilation settings with r = 0.975 for the inspiration pressure, and r = 0.902 for the inspiration time. The nonlinear patient-specific relations of ventilation parameters become transparent and support the determination of individualized ventilator settings according to therapeutic goals. Thus, the algorithm is feasible for a variety of ventilated ICU patients and has the potential of improving lung-protective ventilation by minimizing inspiratory pressures and by helping to avoid the build-up of clinically significant intrinsic positive end

Model-based setting of inspiratory pressure and respiratory rate in pressure-controlled ventilation.

Science.gov (United States)

Schranz, C; Becher, T; Schädler, D; Weiler, N; Möller, K

2014-03-01

Mechanical ventilation carries the risk of ventilator-induced-lung-injury (VILI). To minimize the risk of VILI, ventilator settings should be adapted to the individual patient properties. Mathematical models of respiratory mechanics are able to capture the individual physiological condition and can be used to derive personalized ventilator settings. This paper presents model-based calculations of inspiration pressure (pI), inspiration and expiration time (tI, tE) in pressure-controlled ventilation (PCV) and a retrospective evaluation of its results in a group of mechanically ventilated patients. Incorporating the identified first order model of respiratory mechanics in the basic equation of alveolar ventilation yielded a nonlinear relation between ventilation parameters during PCV. Given this patient-specific relation, optimized settings in terms of minimal pI and adequate tE can be obtained. We then retrospectively analyzed data from 16 ICU patients with mixed pathologies, whose ventilation had been previously optimized by ICU physicians with the goal of minimization of inspiration pressure, and compared the algorithm's 'optimized' settings to the settings that had been chosen by the physicians. The presented algorithm visualizes the patient-specific relations between inspiration pressure and inspiration time. The algorithm's calculated results highly correlate to the physician's ventilation settings with r = 0.975 for the inspiration pressure, and r = 0.902 for the inspiration time. The nonlinear patient-specific relations of ventilation parameters become transparent and support the determination of individualized ventilator settings according to therapeutic goals. Thus, the algorithm is feasible for a variety of ventilated ICU patients and has the potential of improving lung-protective ventilation by minimizing inspiratory pressures and by helping to avoid the build-up of clinically significant intrinsic positive end-expiratory pressure.

Experimental investigation on reduced exposure to pollutants indoors by applying wearable personalized ventilation

DEFF Research Database (Denmark)

Bolashikov, Zhecho; Melikov, Arsen; Spilak, Michal

2013-01-01

of clean air into the breathing zone. Experiments at 23°C (73.4°F) were performed in a full-scale test room with a breathing thermal manikin resembling a seated occupant in a state of thermal comfort, with a realistic free convection flow around the body and breathing cycle. The room air was mixed...... with tracer gas. The personalized ventilation supplied isothermally clean air from circular or elliptical nozzles of different diameters (equivalent diameter: 0.025-0.035 m [0.08-0.12 ft]) positioned near the mouth of the manikin. The enhancement of inhaled air quality was studied by varying the initial...... velocity (0.2-0.6 m/s [0.66- 1.97 fps]), the distance between the nozzles and the mouth (0.02-0.06 m [0.07-0.2 ft]), or the direction of the jet (front, side, or below). The personalized ventilation made it possible to increase up to 94% the portion of clean air into the air inhaled. A wearable...

An innovation wall model based on interlayer ventilation

International Nuclear Information System (INIS)

Feng Jinmei; Lian Zhiwei; Hou Zhijian

2008-01-01

The thermal characteristics of the external wall are important to the energy consumption of the air conditioning system. Great attention should also be paid to the energy loss of the air exhaust. An innovation wall model based on interlayer ventilation is presented in this paper. The interlayer ventilation wall combines the wall and air exhaust of heating, ventilating and air conditioning (HVAC). The results of the experiment show that the energy loss of the exhaust air can be fully recovered by the interlayer ventilation wall. The cooling load can be reduced greatly because the temperature difference between the internal surface of the interlayer ventilation wall and the indoor air is very small. Clearly, the small temperature difference can enhance thermal comfort. In order to popularize the interlayer ventilation wall, technical and economical analysis is presented in this paper. Based on the buildings in the Shanghai area and a standard air conditioning system, a 4 years payback period for interlayer ventilation wall implementation was found according to the analysis

Learning about ventilators

Science.gov (United States)

... medlineplus.gov/ency/patientinstructions/000458.htm Learning about ventilators To use the sharing features on this page, ... fixed or changed. How Does Being on a Ventilator Feel? A person receives medicine to remain comfortable ...

Outcome-based ventilation: A framework for assessing performance, health, and energy impacts to inform office building ventilation decisions.

Science.gov (United States)

Rackes, A; Ben-David, T; Waring, M S

2018-04-23

This article presents an outcome-based ventilation (OBV) framework, which combines competing ventilation impacts into a monetized loss function ($/occ/h) used to inform ventilation rate decisions. The OBV framework, developed for U.S. offices, considers six outcomes of increasing ventilation: profitable outcomes realized from improvements in occupant work performance and sick leave absenteeism; health outcomes from occupant exposure to outdoor fine particles and ozone; and energy outcomes from electricity and natural gas usage. We used the literature to set low, medium, and high reference values for OBV loss function parameters, and evaluated the framework and outcome-based ventilation rates using a simulated U.S. office stock dataset and a case study in New York City. With parameters for all outcomes set at medium values derived from literature-based central estimates, higher ventilation rates' profitable benefits dominated negative health and energy impacts, and the OBV framework suggested ventilation should be ≥45 L/s/occ, much higher than the baseline ~8.5 L/s/occ rate prescribed by ASHRAE 62.1. Only when combining very low parameter estimates for profitable impacts with very high ones for health and energy impacts were all outcomes on the same order. Even then, however, outcome-based ventilation rates were often twice the baseline rate or more. © 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Ceiling personalized ventilation combined with desk fans for reduced direct and indirect cross-contamination and efficient use of office space

International Nuclear Information System (INIS)

Habchi, Carine; Ghali, Kamel; Ghaddar, Nesreen; Chakroun, Walid; Alotaibi, Sorour

2016-01-01

Highlights: • Cross-infection occurs by direct inhalation and contact of contaminated surfaces. • Mixing ventilation performance is degraded at reduced distance between occupants. • Ceiling personalized ventilation reduces significantly cross-contamination. • The optimized system induces large energy savings compared to mixing ventilation. • The optimized system improves the occupation density from 12 to 8 m 2 per occupant. - Abstract: Crowded offices with short distances separating workers’ stations increase the probability of respiratory cross-infection via two different paths. One path is the contaminant transmission through air by direct inhalation and the other is through the body contact of contaminated surfaces and walls. Mixed ventilation principles used today reduces the probability of cross contamination by increasing the distance between the stations challenging the efficient use of the space or by supplying more fresh air in the space which is energy inefficient. In this work, new cooling and ventilation configuration is studied by modeling using computational fluid dynamics with consideration of space occupancy density while providing good indoor air quality. The configuration considers a ceiling personalized ventilation system equipped with desk fans. The ability of the computational fluid dynamics model in computing the thermal, velocity and concentration fields was validated by experiments and published data. The main objective of the performed experiments was to ensure that the developed computational fluid dynamics model can capture the effect of the desk fan flow rate on particle behavior. The studied system is found to provide acceptable indoor air quality at shorter distance between the occupants compared to the mixing system at considerable energy savings. By optimizing the design of the proposed personalized ventilation system, the occupancy density in an office is enhanced to 8 m 2 per occupant compared to 12 m 2 per occupant for

Personal exposure between people in a room ventilated by textile terminals - with and without personalized ventilation

DEFF Research Database (Denmark)

Nielsen, P.V.; Hyldgaard, C.E.; Melikov, Arsen Krikor

2007-01-01

This paper describes an investigation made in a room ventilated by an air distribution system based on a textile terminal. The air distribution in the room is mainly controlled by buoyancy forces from the heat sources, although the flow from the textile terminal can be characterized...... manikin is the source and the other the target. In general it was found that when the air is supplied from the textile terminal alone, the flow in the room is fully mixed with limited protection of the occupants. Selected locations of supply, return, and heat sources can produce a displacement flow...

Intraoperative mechanical ventilation for the pediatric patient.

Science.gov (United States)

Kneyber, Martin C J

2015-09-01

Invasive mechanical ventilation is required when children undergo general anesthesia for any procedure. It is remarkable that one of the most practiced interventions such as pediatric mechanical ventilation is hardly supported by any scientific evidence but rather based on personal experience and data from adults, especially as ventilation itself is increasingly recognized as a harmful intervention that causes ventilator-induced lung injury. The use of low tidal volume and higher levels of positive end-expiratory pressure became an integral part of lung-protective ventilation following the outcomes of clinical trials in critically ill adults. This approach has been readily adopted in pediatric ventilation. However, a clear association between tidal volume and mortality has not been ascertained in pediatrics. In fact, experimental studies have suggested that young children might be less susceptible to ventilator-induced lung injury. As such, no recommendations on optimal lung-protective ventilation strategy in children with or without lung injury can be made. Copyright © 2015 Elsevier Ltd. All rights reserved.

Control of Airborne Infectious Diseases in Ventilated Spaces

DEFF Research Database (Denmark)

Nielsen, Peter V.

2009-01-01

We protect ourselves from airborne cross-infection in the indoor environment by supplying fresh air to a room by natural or mechanical ventilation. The air is distributed in the room according to different principles: mixing ventilation, displacement ventilation, etc. A large amount of air...... to have high ventilation effectiveness. Furthermore, personalized ventilation may reduce the risk of cross-infection, and in some cases, it can also reduce the source of infection. Personalized ventilation can especially be used in hospital wards, aircraft cabins and, in general, where people are in fixed...

Home Mechanical Ventilation: A 12-Year Population-Based Retrospective Cohort Study.

Science.gov (United States)

Povitz, Marcus; Rose, Louise; Shariff, Salimah Z; Leonard, Sean; Welk, Blayne; Jenkyn, Krista Bray; Leasa, David J; Gershon, Andrea S

2018-04-01

Increasing numbers of individuals are being initiated on home mechanical ventilation, including noninvasive (bi-level) and invasive mechanical ventilation delivered via tracheostomy due to chronic respiratory failure to enable symptom management and promote quality of life. Given the high care needs of these individuals, a better understanding of the indications for home mechanical ventilation, and health-care utilization is needed. We performed a retrospective cohort study using provincial health administrative data from Ontario, Canada (population ∼13,000,000). Home mechanical ventilation users were characterized using health administrative data to determine the indications for home mechanical ventilation, the need for acute care at the time of ventilation approval, and their health service use and mortality rates following approval. The annual incidence of home mechanical ventilation approval rose from 1.8/100,000 in 2000 to 5.0/100,000 in 2012, or an annual increase of approximately 0.3/100,000 persons/y. The leading indications were neuromuscular disease, thoracic restriction, and COPD. The indication for the remainder could not be determined due to limitations of the administrative databases. Of the 4,670 individuals, 23.0% commenced home mechanical ventilation following an acute care hospitalization. Among individuals who survived at least 1 y, fewer required hospitalization in the year that followed home mechanical ventilation approval (29.9% vs 39.8%) as compared with the year prior. Utilization of home mechanical ventilation is increasing in Ontario, Canada, and further study is needed to clarify the factors contributing to this and to further optimize utilization of health-care resources. Copyright © 2018 by Daedalus Enterprises.

Economic, Environmental and Health Implications of Enhanced Ventilation in Office Buildings.

Science.gov (United States)

MacNaughton, Piers; Pegues, James; Satish, Usha; Santanam, Suresh; Spengler, John; Allen, Joseph

2015-11-18

Current building ventilation standards are based on acceptable minimums. Three decades of research demonstrates the human health benefits of increased ventilation above these minimums. Recent research also shows the benefits on human decision-making performance in office workers, which translates to increased productivity. However, adoption of enhanced ventilation strategies is lagging. We sought to evaluate two of the perceived potential barriers to more widespread adoption-Economic and environmental costs. We estimated the energy consumption and associated per building occupant costs for office buildings in seven U.S. cities, representing different climate zones for three ventilation scenarios (standard practice (20 cfm/person), 30% enhanced ventilation, and 40 cfm/person) and four different heating, ventilation and air conditioning (HVAC) system strategies (Variable Air Volume (VAV) with reheat and a Fan Coil Unit (FCU), both with and without an energy recovery ventilator). We also estimated emissions of greenhouse gases associated with this increased energy usage, and, for comparison, converted this to the equivalent number of vehicles using greenhouse gas equivalencies. Lastly, we paired results from our previous research on cognitive function and ventilation with labor statistics to estimate the economic benefit of increased productivity associated with increasing ventilation rates. Doubling the ventilation rate from the American Society of Heating, Refrigeration and Air-Conditioning Engineers minimum cost less than $40 per person per year in all climate zones investigated. Using an energy recovery ventilation system significantly reduced energy costs, and in some scenarios led to a net savings. At the highest ventilation rate, adding an ERV essentially neutralized the environmental impact of enhanced ventilation (0.03 additional cars on the road per building across all cities). The same change in ventilation improved the performance of workers by 8

Economic, Environmental and Health Implications of Enhanced Ventilation in Office Buildings

Directory of Open Access Journals (Sweden)

Piers MacNaughton

2015-11-01

Full Text Available Introduction: Current building ventilation standards are based on acceptable minimums. Three decades of research demonstrates the human health benefits of increased ventilation above these minimums. Recent research also shows the benefits on human decision-making performance in office workers, which translates to increased productivity. However, adoption of enhanced ventilation strategies is lagging. We sought to evaluate two of the perceived potential barriers to more widespread adoption—Economic and environmental costs. Methods: We estimated the energy consumption and associated per building occupant costs for office buildings in seven U.S. cities, representing different climate zones for three ventilation scenarios (standard practice (20 cfm/person, 30% enhanced ventilation, and 40 cfm/person and four different heating, ventilation and air conditioning (HVAC system strategies (Variable Air Volume (VAV with reheat and a Fan Coil Unit (FCU, both with and without an energy recovery ventilator. We also estimated emissions of greenhouse gases associated with this increased energy usage, and, for comparison, converted this to the equivalent number of vehicles using greenhouse gas equivalencies. Lastly, we paired results from our previous research on cognitive function and ventilation with labor statistics to estimate the economic benefit of increased productivity associated with increasing ventilation rates. Results: Doubling the ventilation rate from the American Society of Heating, Refrigeration and Air-Conditioning Engineers minimum cost less than $40 per person per year in all climate zones investigated. Using an energy recovery ventilation system significantly reduced energy costs, and in some scenarios led to a net savings. At the highest ventilation rate, adding an ERV essentially neutralized the environmental impact of enhanced ventilation (0.03 additional cars on the road per building across all cities. The same change in ventilation

Predicting adult pulmonary ventilation volume and wearing complianceby on-board accelerometry during personal level exposure assessments

Science.gov (United States)

Rodes, C. E.; Chillrud, S. N.; Haskell, W. L.; Intille, S. S.; Albinali, F.; Rosenberger, M. E.

2012-09-01

BackgroundMetabolic functions typically increase with human activity, but optimal methods to characterize activity levels for real-time predictions of ventilation volume (l min-1) during exposure assessments have not been available. Could tiny, triaxial accelerometers be incorporated into personal level monitors to define periods of acceptable wearing compliance, and allow the exposures (μg m-3) to be extended to potential doses in μg min-1 kg-1 of body weight? ObjectivesIn a pilot effort, we tested: 1) whether appropriately-processed accelerometer data could be utilized to predict compliance and in linear regressions to predict ventilation volumes in real-time as an on-board component of personal level exposure sensor systems, and 2) whether locating the exposure monitors on the chest in the breathing zone, provided comparable accelerometric data to other locations more typically utilized (waist, thigh, wrist, etc.). MethodsPrototype exposure monitors from RTI International and Columbia University were worn on the chest by a pilot cohort of adults while conducting an array of scripted activities (all volumes in-situ. For the subset of participants with complete data (n = 22), linear regressions were constructed (processed accelerometric variable versus ventilation rate) for each participant and exposure monitor type, and Pearson correlations computed to compare across scenarios. ResultsTriaxial accelerometer data were demonstrated to be adequately sensitive indicators for predicting exposure monitor wearing compliance. Strong linear correlations (R values from 0.77 to 0.99) were observed for all participants for both exposure sensor accelerometer variables against ventilation volume for recumbent, sedentary, and ambulatory activities with MET values ˜volume data. Computing accelerometric standard deviations allowed good sensitivity for compliance assessments even for sedentary activities. These pilot findings supported the hypothesis that a common linear

Dispersal of Exhaled Air and Personal Exposure in Displacement Ventilated Rooms

DEFF Research Database (Denmark)

Bjørn, Erik; Nielsen, Peter Vilhelm

2002-01-01

The influence of the human exhalation on flow fields, contaminant distributions, and personal exposures in displacement ventilated rooms is studied together with the effects of physical movement. Experiments are conducted in full-scale test rooms with life-sized breathing thermal manikins....... Numerical simulations support the experiments. Air exhaled through the mouth can lock in a thermally stratified layer, if the vertical temperature gradient in breathing zone height is sufficiently large. With exhalation through the nose, exhaled air flows to the upper part of the room. The exhalation flow...

Recommendations for mechanical ventilation of critically ill children from the Paediatric Mechanical Ventilation Consensus Conference (PEMVECC)

NARCIS (Netherlands)

Kneyber, Martin C. J.; de Luca, Daniele; Calderini, Edoardo; Jarreau, Pierre-Henri; Javouhey, Etienne; Lopez-Herce, Jesus; Hammer, Jurg; Macrae, Duncan; Markhorst, Dick G.; Medina, Alberto; Pons-Odena, Marti; Racca, Fabrizio; Wolf, Gerhard; Biban, Paolo; Brierley, Joe; Rimensberger, Peter C.

2017-01-01

Purpose: Much of the common practice in paediatric mechanical ventilation is based on personal experiences and what paediatric critical care practitioners have adopted from adult and neonatal experience. This presents a barrier to planning and interpretation of clinical trials on the use of specific

[Anesthesia ventilators].

Science.gov (United States)

Otteni, J C; Beydon, L; Cazalaà, J B; Feiss, P; Nivoche, Y

1997-01-01

To review anaesthesia ventilators in current use in France by categories of ventilators. References were obtained from computerized bibliographic search. (Medline), recent review articles, the library of the service and personal files. Anaesthesia ventilators can be allocated into three groups, depending on whether they readminister expired gases or not or allow both modalities. Contemporary ventilators provide either constant volume ventilation, or constant pressure ventilation, with or without a pressure plateau. Ventilators readministering expired gases after CO2 absorption, or closed circuit ventilators, are either of a double- or a single-circuit design. Double-circuit ventilators, or pneumatical bag or bellows squeezers, or bag-in-bottle or bellows-in-bottle (or box) ventilators, consist of a primary, or driving circuit (bottle or box) and a secondary or patient circuit (including a bag or a bellows or membrane chambers). Bellows-in-bottle ventilators have either standing bellows ascending at expiration, or hanging bellows, descending at expiration. Ascending bellows require a positive pressure of about 2 cmH2O throughout exhalation to allow the bellows to refill. The expired gas volume is a valuable indicator for leak and disconnection. Descending bellows generate a slight negative pressure during exhalation. In case of leak or disconnection they aspirate ambient air and cannot act therefore as an indicator for integrity of the circuit and the patient connection. Closed circuit ventilators with a single-circuit (patient circuit) include a insufflating device consisting either in a bellows or a cylinder with a piston, operated by a electric or pneumatic motor. As the hanging bellows of the double circuit ventilators, they generate a slight negative pressure during exhalation and aspirate ambient air in case of leak or disconnection. Ventilators not designed for the readministration of expired gases, or open circuit ventilators, are generally stand

Evaluation of comfort level in desks equipped with two personalized ventilation systems in slightly warm environments

Energy Technology Data Exchange (ETDEWEB)

Conceicao, Eusebio Z.E. [Faculdade de Ciencias e Tecnologia - Universidade do Algarve, Campus de Gambelas, 8005-139 Faro (Portugal); Lucio, Manuela J.R. [Agrupamento Vertical Professor Paula Nogueira, R. Comunidade Lusiada, 8700-000 Olhao (Portugal); Rosa, Silvia P.; Custodio, Ana L.V.; Andrade, Renata L.; Meira, Maria J.P.A. [Faculdade de Ciencias do Mar e do Ambiente - Universidade do Algarve, Campus de Gambelas, 8005-139 Faro (Portugal)

2010-03-15

In this work the comfort level, namely the thermal comfort, local thermal discomfort and air quality levels, in a classroom with desks equipped with two personalized ventilation systems, in slightly warm environments, is evaluated. A manikin, a ventilated classroom desk, two indoor climate analyzers, a multi-nodal human thermal comfort numerical model and a computational fluid dynamic numerical model, are used. The classroom desk, with double occupation capacity, is used by a student, located in the right side seat. Each personalized ventilation system is equipped with one air terminal device located above the desk writing area, in front to the trunk area, and an other located below the desk writing area, in front to the legs area. The thermal comfort level is evaluated by the developed multi-nodal human thermal comfort numerical model, using a PMV value, the local thermal discomfort level, namely the draught risk and the air velocity fluctuation equivalent frequencies, is evaluated by empirical models, while the air quality level and the detailed airflow around the manikin are evaluated by the computational fluid dynamic numerical model. In the experimental tests the mean air velocity and the turbulence intensity in the upper air terminal device are 3.5 m/s and 9.7%, while in the lower air terminal device are 2.6 m/s and 15.2%. The mean air temperature in the air terminal devices is around 28 C, while the mean radiant temperature in the occupation area, the mean air temperature far from the occupation area and the internal mean air relative humidity were, respectively, 28 C, 28 C and 50%. The air velocity and temperature around the occupant are measured around 15 human body sections. The actual personalized ventilation system, which promotes an ascendant airflow around the occupant with highest air renovation rate in the respiration area, promotes acceptable thermal comfort conditions and air quality in the respiration area in accord to the present standards. The

Association between substandard classroom ventilation rates and students' academic achievement.

Science.gov (United States)

Haverinen-Shaughnessy, U; Moschandreas, D J; Shaughnessy, R J

2011-04-01

This study focuses on the relationship between classroom ventilation rates and academic achievement. One hundred elementary schools of two school districts in the southwest United States were included in the study. Ventilation rates were estimated from fifth-grade classrooms (one per school) using CO(2) concentrations measured during occupied school days. In addition, standardized test scores and background data related to students in the classrooms studied were obtained from the districts. Of 100 classrooms, 87 had ventilation rates below recommended guidelines based on ASHRAE Standard 62 as of 2004. There is a linear association between classroom ventilation rates and students' academic achievement within the range of 0.9-7.1 l/s per person. For every unit (1 l/s per person) increase in the ventilation rate within that range, the proportion of students passing standardized test (i.e., scoring satisfactory or above) is expected to increase by 2.9% (95%CI 0.9-4.8%) for math and 2.7% (0.5-4.9%) for reading. The linear relationship observed may level off or change direction with higher ventilation rates, but given the limited number of observations, we were unable to test this hypothesis. A larger sample size is needed for estimating the effect of classroom ventilation rates higher than 7.1 l/s per person on academic achievement. The results of this study suggest that increasing the ventilation rates toward recommended guideline ventilation rates in classrooms should translate into improved academic achievement of students. More studies are needed to fully understand the relationships between ventilation rate, other indoor environmental quality parameters, and their effects on students' health and achievement. Achieving the recommended guidelines and pursuing better understanding of the underlying relationships would ultimately support both sustainable and productive school environments for students and personnel. © 2010 John Wiley & Sons A/S.

The effect of a personalized ventilation system on perceived air quality and SBS symptoms

DEFF Research Database (Denmark)

Kaczmarczyk, Jan; Zeng, Q.; Melikov, Arsen Krikor

2002-01-01

Perceived air quality, SBS symptoms and performance were studied with 30 human subjects. Experiments were performed in an office set-up with six workplaces, each equipped with a Personalized Ventilation System (PVS). Each PVS allowed the amount of supply air and its direction to be controlled...... condition in regard to perceived air quality, perception of freshness and intensity of SBS symptoms was when PVS supplied outdoor air at 20 deg.C. Perceived air quality in this case was significantly better (p....... Subjects participated in four experiments: (1) PVS supplying outdoor air at 20 deg.C; (2) PVS supplying outdoor air at 23 deg.C; (3) PVS supplying recirculated room air; and (4) mixing ventilation. Room temperature was kept constant at 23 deg.C and relative humidity at 30%. Results showed that the best...

Practical mine ventilation optimization based on genetic algorithms for free splitting networks

Energy Technology Data Exchange (ETDEWEB)

Acuna, E.; Maynard, R.; Hall, S. [Laurentian Univ., Sudbury, ON (Canada). Mirarco Mining Innovation; Hardcastle, S.G.; Li, G. [Natural Resources Canada, Sudbury, ON (Canada). CANMET Mining and Mineral Sciences Laboratories; Lowndes, I.S. [Nottingham Univ., Nottingham (United Kingdom). Process and Environmental Research Division; Tonnos, A. [Bestech, Sudbury, ON (Canada)

2010-07-01

The method used to optimize the design and operation of mine ventilation has generally been based on case studies and expert knowledge. It has yet to benefit from optimization techniques used and proven in other fields of engineering. Currently, optimization of mine ventilation systems is a manual based decision process performed by an experienced mine ventilation specialist assisted by commercial ventilation distribution solvers. These analysis tools are widely used in the mining industry to evaluate the practical and economic viability of alternative ventilation system configurations. The scenario which is usually selected is the one that reports the lowest energy consumption while delivering the required airflow distribution. Since most commercial solvers do not have an integrated optimization algorithm network, the process of generating a series of potential ventilation solutions using the conventional iterative design strategy can be time consuming. For that reason, a genetic algorithm (GA) optimization routine was developed in combination with a ventilation solver to determine the potential optimal solutions of a primary mine ventilation system based on a free splitting network. The optimization method was used in a small size mine ventilation network. The technique was shown to have the capacity to generate good feasible solutions and improve upon the manual results obtained by mine ventilation specialists. 9 refs., 7 tabs., 3 figs.

Contextualizing ethics: ventilators, H1N1 and marginalized populations.

Science.gov (United States)

Silva, Diego S; Nie, Jason X; Rossiter, Kate; Sahni, Sachin; Upshur, Ross E G

2010-01-01

If the H1N1 pandemic worsens, there may not be enough ventilated beds to care for all persons with respiratory failure. To date, researchers who explicitly discuss the ethics of intensive care unit admission and the allocation of ventilators during an influenza pandemic have based criteria predominantly on the principles of utility and efficiency, that is, promoting actions that maximize the greatest good for the greatest number of people. However, haphazardly applying utility and efficiency potentially disadvantages marginalized populations who might be at increased risk of severe reactions to H1N1. In Canada, Aboriginals represent 3% of Canadians, yet 11% of H1N1 cases requiring hospitalization involve Aboriginal persons. Aboriginal persons suffer from high rates of obesity due to socio-economic inequalities. Obesity is also a risk factor for severe H1N1 reactions. Yet, since obesity is found to increase the duration of stay in ventilated beds and a long stay is not considered an optimal use of ventilators, applying the principles of utility and efficiency may magnify existing social inequalities. Although promoting utility and efficiency is important, other ethical principles, such as equity and need, require thoughtful consideration and implementation. Furthermore, since public resources are being used to address a public health hazard, the viewpoints of the public, and specifically stakeholders who will be disproportionately affected, should inform decision-makers. Finally, giving attention to the needs and rights of marginalized populations means that ventilators should not be allocated based on criteria that exacerbate the social injustices faced by these groups of people.

An evidence-based recommendation on bed head elevation for mechanically ventilated patients

OpenAIRE

Ni?l-Weise, Barbara S; Gastmeier, Petra; Kola, Axel; Vonberg, Ralf P; Wille, Jan C; van den Broek, Peterhans J

2011-01-01

Introduction A semi-upright position in ventilated patients is recommended to prevent ventilator-associated pneumonia (VAP) and is one of the components in the Ventilator Bundle of the Institute for Health Care Improvement. This recommendation, however, is not an evidence-based one. Methods A systematic review on the benefits and disadvantages of semi-upright position in ventilated patients was done according to PRISMA guidelines. Then a European expert panel developed a recommendation based ...

Effects of Classroom Ventilation Rate and Temperature on Students' Test Scores.

Science.gov (United States)

Haverinen-Shaughnessy, Ulla; Shaughnessy, Richard J

2015-01-01

Using a multilevel approach, we estimated the effects of classroom ventilation rate and temperature on academic achievement. The analysis is based on measurement data from a 70 elementary school district (140 fifth grade classrooms) from Southwestern United States, and student level data (N = 3109) on socioeconomic variables and standardized test scores. There was a statistically significant association between ventilation rates and mathematics scores, and it was stronger when the six classrooms with high ventilation rates that were indicated as outliers were filtered (> 7.1 l/s per person). The association remained significant when prior year test scores were included in the model, resulting in less unexplained variability. Students' mean mathematics scores (average 2286 points) were increased by up to eleven points (0.5%) per each liter per second per person increase in ventilation rate within the range of 0.9-7.1 l/s per person (estimated effect size 74 points). There was an additional increase of 12-13 points per each 1°C decrease in temperature within the observed range of 20-25°C (estimated effect size 67 points). Effects of similar magnitude but higher variability were observed for reading and science scores. In conclusion, maintaining adequate ventilation and thermal comfort in classrooms could significantly improve academic achievement of students.

Person-centred care during prolonged weaning from mechanical ventilation, nurses' views: an interview study.

Science.gov (United States)

Cederwall, Carl-Johan; Olausson, Sepideh; Rose, Louise; Naredi, Silvana; Ringdal, Mona

2018-03-19

To determine: 1) if the three elements of person-centred care (initiating, working and safeguarding the partnership) were present, and 2) to identify evidence of barriers to person-centred care during prolonged weaning from mechanical ventilation. Secondary analysis of semi structured interviews with 19 critical care nurses using theoretical thematic analysis. This study was conducted in three Swedish intensive care units, one in a regional hospital and two in a university hospital. Three themes and nine subthemes related to person-centred care were identified. The three themes included: 1) 'finding a person behind the patient' related to the 'initiating the partnership' phase, 2) 'striving to restore patient́s sense of control' related to 'working the partnership' phase and 3) 'impact of patient involvement' related to 'safeguarding the partnership' phase of person-centred care'. Additionally a further theme 'barriers to person-centred care' was identified. We found evidence of all three person-centred care routines. Barriers to person-centred care comprised of lack team collaboration and resources. Facilitating patients to actively participate in decision-making during the weaning process may optimise weaning outcomes and warrants further research. Copyright © 2017 Elsevier Ltd. All rights reserved.

Recommendations for mechanical ventilation of critically ill children from the Paediatric Mechanical Ventilation Consensus Conference (PEMVECC).

Science.gov (United States)

Kneyber, Martin C J; de Luca, Daniele; Calderini, Edoardo; Jarreau, Pierre-Henri; Javouhey, Etienne; Lopez-Herce, Jesus; Hammer, Jürg; Macrae, Duncan; Markhorst, Dick G; Medina, Alberto; Pons-Odena, Marti; Racca, Fabrizio; Wolf, Gerhard; Biban, Paolo; Brierley, Joe; Rimensberger, Peter C

2017-12-01

Much of the common practice in paediatric mechanical ventilation is based on personal experiences and what paediatric critical care practitioners have adopted from adult and neonatal experience. This presents a barrier to planning and interpretation of clinical trials on the use of specific and targeted interventions. We aim to establish a European consensus guideline on mechanical ventilation of critically children. The European Society for Paediatric and Neonatal Intensive Care initiated a consensus conference of international European experts in paediatric mechanical ventilation to provide recommendations using the Research and Development/University of California, Los Angeles, appropriateness method. An electronic literature search in PubMed and EMBASE was performed using a combination of medical subject heading terms and text words related to mechanical ventilation and disease-specific terms. The Paediatric Mechanical Ventilation Consensus Conference (PEMVECC) consisted of a panel of 15 experts who developed and voted on 152 recommendations related to the following topics: (1) general recommendations, (2) monitoring, (3) targets of oxygenation and ventilation, (4) supportive measures, (5) weaning and extubation readiness, (6) normal lungs, (7) obstructive diseases, (8) restrictive diseases, (9) mixed diseases, (10) chronically ventilated patients, (11) cardiac patients and (12) lung hypoplasia syndromes. There were 142 (93.4%) recommendations with "strong agreement". The final iteration of the recommendations had none with equipoise or disagreement. These recommendations should help to harmonise the approach to paediatric mechanical ventilation and can be proposed as a standard-of-care applicable in daily clinical practice and clinical research.

Anaesthesia ventilators

OpenAIRE

Jain, Rajnish K; Swaminathan, Srinivasan

2013-01-01

Anaesthesia ventilators are an integral part of all modern anaesthesia workstations. Automatic ventilators in the operating rooms, which were very simple with few modes of ventilation when introduced, have become very sophisticated with many advanced ventilation modes. Several systems of classification of anaesthesia ventilators exist based upon various parameters. Modern anaesthesia ventilators have either a double circuit, bellow design or a single circuit piston configuration. In the bello...

Energy analysis of the personalized ventilation system in hot and humid climates

DEFF Research Database (Denmark)

Schiavon, S.; Melikov, Arsen Krikor; Sekhar, C.

2010-01-01

, inhaled air quality, thermal comfort, and self-estimated productivity. Little is known about its energy performance. In this study, the energy consumption of a personalized ventilation system introduced in an office building located in a hot and humid climate (Singapore) has been investigated by means...... effectiveness of PV; (b) increasing the maximum allowed room air temperature due to PV capacity to control the microclimate; (c) supplying the outdoor air only when the occupant is at the desk. The strategy to control the supply air temperature does not affect the energy consumption in a hot and humid climate....

Effects of Classroom Ventilation Rate and Temperature on Students' Test Scores.

Directory of Open Access Journals (Sweden)

Ulla Haverinen-Shaughnessy

Full Text Available Using a multilevel approach, we estimated the effects of classroom ventilation rate and temperature on academic achievement. The analysis is based on measurement data from a 70 elementary school district (140 fifth grade classrooms from Southwestern United States, and student level data (N = 3109 on socioeconomic variables and standardized test scores. There was a statistically significant association between ventilation rates and mathematics scores, and it was stronger when the six classrooms with high ventilation rates that were indicated as outliers were filtered (> 7.1 l/s per person. The association remained significant when prior year test scores were included in the model, resulting in less unexplained variability. Students' mean mathematics scores (average 2286 points were increased by up to eleven points (0.5% per each liter per second per person increase in ventilation rate within the range of 0.9-7.1 l/s per person (estimated effect size 74 points. There was an additional increase of 12-13 points per each 1°C decrease in temperature within the observed range of 20-25°C (estimated effect size 67 points. Effects of similar magnitude but higher variability were observed for reading and science scores. In conclusion, maintaining adequate ventilation and thermal comfort in classrooms could significantly improve academic achievement of students.

Effects of Classroom Ventilation Rate and Temperature on Students’ Test Scores

Science.gov (United States)

2015-01-01

Using a multilevel approach, we estimated the effects of classroom ventilation rate and temperature on academic achievement. The analysis is based on measurement data from a 70 elementary school district (140 fifth grade classrooms) from Southwestern United States, and student level data (N = 3109) on socioeconomic variables and standardized test scores. There was a statistically significant association between ventilation rates and mathematics scores, and it was stronger when the six classrooms with high ventilation rates that were indicated as outliers were filtered (> 7.1 l/s per person). The association remained significant when prior year test scores were included in the model, resulting in less unexplained variability. Students’ mean mathematics scores (average 2286 points) were increased by up to eleven points (0.5%) per each liter per second per person increase in ventilation rate within the range of 0.9–7.1 l/s per person (estimated effect size 74 points). There was an additional increase of 12–13 points per each 1°C decrease in temperature within the observed range of 20–25°C (estimated effect size 67 points). Effects of similar magnitude but higher variability were observed for reading and science scores. In conclusion, maintaining adequate ventilation and thermal comfort in classrooms could significantly improve academic achievement of students. PMID:26317643

Displacement Ventilation

DEFF Research Database (Denmark)

Bjørn, Erik; Mattsson, Magnus; Sandberg, Mats

Full-scale experiments were made in a displacement ventilated room with two breathing thermal manikins to study the effect of movements and breathing on the vertical contaminant distribution, and on the personal exposure of occupants. Concentrations were measured with tracer gas equipment...

MR-based assessment of pulmonary ventilation-perfusion in animal models

International Nuclear Information System (INIS)

Yang Jian; Wan Mingxi; Guo Youmin

2003-01-01

Objective: To show the feasibility and value in the diagnosis of airway obstruction and pulmonary embolism with MR oxygen-enhanced ventilation combined with pulmonary perfusion imaging. Methods: Eight canines were implemented for peripheral pulmonary embolism by intravenous injection of gelfoam granules at pulmonary segmental arterial level, and five of them were formed airway obstruction models by inserting self-made balloon catheter at second-bronchia. The oxygen-enhanced MR ventilation imaging was introduced by subtracting the images of pre- and post- inhaled pure oxygen. The MR pulmonary perfusion imaging was achieved by the first-pass contrast agent method. Moreover, the manifestation of MR ventilation and perfusion imaging was observed and contradistinguished with that of general pathologic anatomy, ventilation-perfusion scintigraphy, and pulmonary angiography. Results: The manifestations of airway obstruction regions in MR ventilation and perfusion imaging were matched, but those of pulmonary embolism regions were dismatched. The defect range of airway obstruction in MR ventilation image was smaller than that in ventilation scintigraphy. The abnormal perfusion regions of pulmonary embolism were divided into defect regions and reduce regions based on the time courses of signal intensity changes. The sensitivity and specificity of diagnosis on pulmonary embolism by MR ventilation combined with perfusion technique were 75.0% and 98.1%. The diagnostic results were in good coherence with ventilation-perfusion scintigraphy and pulmonary angiography (K=0.743, 0.899). Conclusion: The MR oxygen-enhanced ventilation combined with pulmonary perfusion imaging can be used to diagnose the airway and vascular abnormity in lung. This technique resembles the ventilation-perfusion scintigraphy. It can provide quantitative functional information and better spatial and temporal resolution, and possesses the value of clinical application

Personal Exposure Between People in a Room Ventilated by Textile Terminals

DEFF Research Database (Denmark)

Nielsen, Peter V.; Hyldgård, Carl-Erik; Melikov, Arsen

2007-01-01

This paper describes an investigation made in a room ventilated by an air distribution system based on a textile terminal. The air distribution in the room is mainly controlled by buoyancy forces from the heat sources, although the flow from the textile terminal can be characterized as a displace...

Development of an Outdoor Temperature-Based Control Algorithm for Residential Mechanical Ventilation Control

Energy Technology Data Exchange (ETDEWEB)

Less, Brennan [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Walker, Iain [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Tang, Yihuan [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

2014-06-01

Smart ventilation systems use controls to ventilate more during those periods that provide either an energy or IAQ advantage (or both) and less during periods that provide a dis advantage. Using detailed building simulations, this study addresses one of the simplest and lowest cost types of smart controllers —outdoor temperature- based control. If the outdoor temperature falls below a certain cut- off, the fan is simply turned off. T he main principle of smart ventilation used in this study is to shift ventilation from time periods with large indoor -outdoor temperature differences, to periods where these differences are smaller, and their energy impacts are expected to be less. Energy and IAQ performance are assessed relative to a base case of a continuously operated ventilation fan sized to comply with ASHRAE 62.2-2013 whole house ventilation requirements. In order to satisfy 62.2-2013, annual pollutant exposure must be equivalent between the temperature controlled and continuous fan cases. This requires ventilation to be greater than 62.2 requirements when the ventilation system operates. This is achieved by increasing the mechanical ventilation system air flow rates.

The comparison of manual and LabVIEW-based fuzzy control on mechanical ventilation.

Science.gov (United States)

Guler, Hasan; Ata, Fikret

2014-09-01

The aim of this article is to develop a knowledge-based therapy for management of rats with respiratory distress. A mechanical ventilator was designed to achieve this aim. The designed ventilator is called an intelligent mechanical ventilator since fuzzy logic was used to control the pneumatic equipment according to the rat's status. LabVIEW software was used to control all equipments in the ventilator prototype and to monitor respiratory variables in the experiment. The designed ventilator can be controlled both manually and by fuzzy logic. Eight female Wistar-Albino rats were used to test the designed ventilator and to show the effectiveness of fuzzy control over manual control on pressure control ventilation mode. The anesthetized rats were first ventilated for 20 min manually. After that time, they were ventilated for 20 min by fuzzy logic. Student's t-test for p < 0.05 was applied to the measured minimum, maximum and mean peak inspiration pressures to analyze the obtained results. The results show that there is no statistical difference in the rat's lung parameters before and after the experiments. It can be said that the designed ventilator and developed knowledge-based therapy support artificial respiration of living things successfully. © IMechE 2014.

Thermal comfort and IAQ assessment of under-floor air distribution system integrated with personalized ventilation in hot and humid climate

DEFF Research Database (Denmark)

Li, Ruixin; Sekhar, S.C.; Melikov, Arsen Krikor

2010-01-01

The potential for improving occupants' thermal comfort with personalized ventilation (PV) system combined with under-floor air distribution (UFAD) system was explored through human response study. The hypothesis was that cold draught at feet can be reduced when relatively warm air is supplied...... of the results obtained reveal improved acceptability of perceived air quality and improved thermal sensation with PV-UFAD in comparison with the reference case of UFAD alone or mixing ventilation with ceiling supply diffuser. The local thermal sensation at the feet was also improved when warmer UFAD supply air...

Anaesthesia ventilators

Directory of Open Access Journals (Sweden)

Rajnish K Jain

2013-01-01

Full Text Available Anaesthesia ventilators are an integral part of all modern anaesthesia workstations. Automatic ventilators in the operating rooms, which were very simple with few modes of ventilation when introduced, have become very sophisticated with many advanced ventilation modes. Several systems of classification of anaesthesia ventilators exist based upon various parameters. Modern anaesthesia ventilators have either a double circuit, bellow design or a single circuit piston configuration. In the bellows ventilators, ascending bellows design is safer than descending bellows. Piston ventilators have the advantage of delivering accurate tidal volume. They work with electricity as their driving force and do not require a driving gas. To enable improved patient safety, several modifications were done in circle system with the different types of anaesthesia ventilators. Fresh gas decoupling is a modification done in piston ventilators and in descending bellows ventilator to reduce th incidence of ventilator induced volutrauma. In addition to the conventional volume control mode, modern anaesthesia ventilators also provide newer modes of ventilation such as synchronised intermittent mandatory ventilation, pressure-control ventilation and pressure-support ventilation (PSV. PSV mode is particularly useful for patients maintained on spontaneous respiration with laryngeal mask airway. Along with the innumerable benefits provided by these machines, there are various inherent hazards associated with the use of the ventilators in the operating room. To use these workstations safely, it is important for every Anaesthesiologist to have a basic understanding of the mechanics of these ventilators and breathing circuits.

Anaesthesia ventilators.

Science.gov (United States)

Jain, Rajnish K; Swaminathan, Srinivasan

2013-09-01

Anaesthesia ventilators are an integral part of all modern anaesthesia workstations. Automatic ventilators in the operating rooms, which were very simple with few modes of ventilation when introduced, have become very sophisticated with many advanced ventilation modes. Several systems of classification of anaesthesia ventilators exist based upon various parameters. Modern anaesthesia ventilators have either a double circuit, bellow design or a single circuit piston configuration. In the bellows ventilators, ascending bellows design is safer than descending bellows. Piston ventilators have the advantage of delivering accurate tidal volume. They work with electricity as their driving force and do not require a driving gas. To enable improved patient safety, several modifications were done in circle system with the different types of anaesthesia ventilators. Fresh gas decoupling is a modification done in piston ventilators and in descending bellows ventilator to reduce th incidence of ventilator induced volutrauma. In addition to the conventional volume control mode, modern anaesthesia ventilators also provide newer modes of ventilation such as synchronised intermittent mandatory ventilation, pressure-control ventilation and pressure-support ventilation (PSV). PSV mode is particularly useful for patients maintained on spontaneous respiration with laryngeal mask airway. Along with the innumerable benefits provided by these machines, there are various inherent hazards associated with the use of the ventilators in the operating room. To use these workstations safely, it is important for every Anaesthesiologist to have a basic understanding of the mechanics of these ventilators and breathing circuits.

Anaesthesia ventilators

Science.gov (United States)

Jain, Rajnish K; Swaminathan, Srinivasan

2013-01-01

Anaesthesia ventilators are an integral part of all modern anaesthesia workstations. Automatic ventilators in the operating rooms, which were very simple with few modes of ventilation when introduced, have become very sophisticated with many advanced ventilation modes. Several systems of classification of anaesthesia ventilators exist based upon various parameters. Modern anaesthesia ventilators have either a double circuit, bellow design or a single circuit piston configuration. In the bellows ventilators, ascending bellows design is safer than descending bellows. Piston ventilators have the advantage of delivering accurate tidal volume. They work with electricity as their driving force and do not require a driving gas. To enable improved patient safety, several modifications were done in circle system with the different types of anaesthesia ventilators. Fresh gas decoupling is a modification done in piston ventilators and in descending bellows ventilator to reduce th incidence of ventilator induced volutrauma. In addition to the conventional volume control mode, modern anaesthesia ventilators also provide newer modes of ventilation such as synchronised intermittent mandatory ventilation, pressure-control ventilation and pressure-support ventilation (PSV). PSV mode is particularly useful for patients maintained on spontaneous respiration with laryngeal mask airway. Along with the innumerable benefits provided by these machines, there are various inherent hazards associated with the use of the ventilators in the operating room. To use these workstations safely, it is important for every Anaesthesiologist to have a basic understanding of the mechanics of these ventilators and breathing circuits. PMID:24249886

Meeting Residential Ventilation Standards Through Dynamic Control of Ventilation Systems

OpenAIRE

Sherman, Max H.

2011-01-01

Existing ventilation standards, including American Society of Heating, Refrigerating, and Air-conditioning Engineers (ASHRAE) Standard 62.2, specify continuous operation of a defined mechanical ventilation system to provide minimum ventilation, with time-based intermittent operation as an option. This requirement ignores several factors and concerns including: other equipment such as household exhaust fans that might incidentally provide ventilation, negative impacts of ventilation when outd...

Rising damp in building walls: the wall base ventilation system

Energy Technology Data Exchange (ETDEWEB)

Guimaraes, A.S.; Delgado, J.M.P.Q.; Freitas, V.P. de [Faculdade de Engenharia da Universidade do Porto, Laboratorio de Fisica das Construcoes (LFC), Departamento de Engenharia Civil, Porto (Portugal)

2012-12-15

This work intends to validate a new system for treating rising damp in historic buildings walls. The results of laboratory experiments show that an efficient way of treating rising damp is by ventilating the wall base, using the HUMIVENT technique. The analytical model presented describes very well the observed features of rising damp in walls, verified by laboratory tests, who contributed for a simple sizing of the wall base ventilation system that will be implemented in historic buildings. (orig.)

Ventilative Cooling

DEFF Research Database (Denmark)

Heiselberg, Per Kvols; Kolokotroni, Maria

This report, by venticool, summarises the outcome of the work of the initial working phase of IEA ECB Annex 62 Ventilative Cooling and is based on the findings in the participating countries. It presents a summary of the first official Annex 62 report that describes the state-of-the-art of ventil......This report, by venticool, summarises the outcome of the work of the initial working phase of IEA ECB Annex 62 Ventilative Cooling and is based on the findings in the participating countries. It presents a summary of the first official Annex 62 report that describes the state......-of-the-art of ventilative cooling potentials and limitations, its consideration in current energy performance regulations, available building components and control strategies and analysis methods and tools. In addition, the report provides twenty six examples of operational buildings using ventilative cooling ranging from...

Comparative analysis of parameters of oxygenation, ventilation and acid-base status during intraoperative application of conventional and protective lung ventilation

Directory of Open Access Journals (Sweden)

Videnović N.

2015-01-01

Full Text Available The aim of this study was to perform a comparative analysis applied conventional (traditional and protective mechanical lung ventilation in clinical conditions with regard to intraoperative parameters changes of oxygenation, ventilation and acid-base status. This was a prospective study that included 240 patients. All patients underwent the same elective surgery (classic cholecystectomy. Patients were divided into two groups of 120 patients, A and B. In group A during the operation had received conventional lung ventilation with tidal volume of 10-15 ml/kg body weight, respiratory rate 12/min. and a PEEP zero. In group B was applied protective lung ventilation with a tidal volume of 6-8 ml/kg body weight, respiratory rate 12/min. and a PEEP of 7 mbar. Monitoring of oxygenation included the monitoring SaO2 and PaO2. Monitoring of ventilation included the determination of the value of tidal volume and minute volume ventilation, peak inspiratory pressure (Ppeak, medium pressure in the airway (Paw.mean, PEEP, PaCO2 and EtCO2. Monitoring of acid-base status was performed via determination of the pH values of arterial blood. Monitoring was carried out in four intervals: T1 - 5-10 minutes after the establishment of the airway, T2 - after opening peritoneum, T3 - after removal of the gallbladder, T4 - after the closure of the abdominal wall. All monitoring results are presented as mean. The statistical significance of differences in mean values was tested by t - test mean values in the case of two independent samples. As a statistical significance test taken as standard values p <0.01 and p <0.001. Comparative analysis of the value of SaO2, PaO2, Ppeak did not reach statistical significance. Statistical significance there is in the analysis of values of tidal volume and Paw.mean (p <0.001. Analysis of PaCO2 and pH of arterial blood showed no statistical significance in the first interval measurements but did interval T2-T4 (p <0.001. Based on the

Ventilation and ventilation/perfusion ratios

International Nuclear Information System (INIS)

Valind, S.O.

1989-01-01

The thesis is based on five different papers. The labelling of specific tracer compounds with positron emitting radionuclides enables a range of structural, physiological and biochemical parameters in the lung to be measured non-invasively, using positron emission tomography. This concept affords a unique opportunity for in vivo studies of different expressions of pulmonary pathophysiology at the regional level. The present thesis describes the application of positron emission tomography to the measurements of ventilation and ventilation/perfusion ratios using inert gas tracers, neon-19 and nitrogen-13 respectively. The validity of the methods applied was investigated with respect to the transport of inert gas tracers in the human lung. Both ventilation and the ventilation/perfusion ratio may be obtained with errors less than 10 % in the normal lung. In disease, however, errors may increase in those instances where the regional ventilation is very low or the intra-regional gas flow distribution is markedly nonuniform. A 2-3 fold increase in ventilation was demonstrated in normal nonsmoking subjects going from ventral to dorsal regions in the supine posture. These large regional differences could be well explained by the intrinsic elastic properties of lung tissue, considering the gravitational gradient in transpulmonary pressure. In asymptomatic smokers substantial regional ventilatroy abnormalities were found whilst the regional gas volume was similar in smokers and nonsmokers. The uncoupling between ventilation and gas volume probably reflects inflammatory changes in the airways. The regional differences in dV/dt/dQ/dt were relatively small and blood flow was largely matched to ventilation in the supine posture. However, small regions of lung with very low ventilation, unmatched by blood flow commonly exists in the most dependent parts of the lung in both smokers and nonsmokers. (29 illustrations, 7 tables, 113 references)

Guidelines For Health-Based Ventilation In Europe

DEFF Research Database (Denmark)

Wargocki, Pawel; Carrer, Paolo; de Oliveira Fernandes, Eduardo

2014-01-01

The burden of disease (BoD) associated with major air exposures indoors in 26 European countries was recently accounted for loss of two million healthy life years annually expressed as disability adjusted life years (DALYs) (Jantunen et al., 2011). The development of health-based ventilation...

Review and Extension of CO2-Based Methods to Determine Ventilation Rates with Application to School Classrooms

Directory of Open Access Journals (Sweden)

Stuart Batterman

2017-02-01

Full Text Available The ventilation rate (VR is a key parameter affecting indoor environmental quality (IEQ and the energy consumption of buildings. This paper reviews the use of CO2 as a “natural” tracer gas for estimating VRs, focusing on applications in school classrooms. It provides details and guidance for the steady-state, build-up, decay and transient mass balance methods. An extension to the build-up method and an analysis of the post-exercise recovery period that can increase CO2 generation rates are presented. Measurements in four mechanically-ventilated school buildings demonstrate the methods and highlight issues affecting their applicability. VRs during the school day fell below recommended minimum levels, and VRs during evening and early morning were on the order of 0.1 h−1, reflecting shutdown of the ventilation systems. The transient mass balance method was the most flexible and advantageous method given the low air change rates and dynamic occupancy patterns observed in the classrooms. While the extension to the build-up method improved stability and consistency, the accuracy of this and the steady-state method may be limited. Decay-based methods did not reflect the VR during the school day due to heating, ventilation and air conditioning (HVAC system shutdown. Since the number of occupants in classrooms changes over the day, the VR expressed on a per person basis (e.g., L·s−1·person−1 depends on the occupancy metric. If occupancy measurements can be obtained, then the transient mass balance method likely will provide the most consistent and accurate results among the CO2-based methods. Improved VR measurements can benefit many applications, including research examining the linkage between ventilation and health.

WE-AB-202-06: Correlating Lung CT HU with Transformation-Based and Xe-CT Derived Ventilation

International Nuclear Information System (INIS)

Du, K; Patton, T; Bayouth, J; Reinhardt, J; Christensen, G

2016-01-01

Purpose: Regional lung ventilation is useful to reduce radiation-induced function damage during lung cancer radiation therapy. Recently a new direct HU (Hounsfield unit)-based method was proposed to estimate the ventilation potential without image registration. The purpose of this study is to examine if there is a functional dependence between HU values and transformation-based or Xe-CT derived ventilation. Methods: 4DCT images acquired from 13 patients prior to radiation therapy and 4 mechanically ventilated sheep subjects which also have associated Xe-CT images were used for this analysis. Transformation-based ventilation was computed using Jacobian determinant of the transformation field between peak-exhale and peak-inhale 4DCT images. Both transformation and Xe-CT derived ventilation was computed for each HU bin. Color scatter plot and cumulative histogram were used to compare and validate the direct HU-based method. Results: There was little change of the center and shape of the HU histograms between free breathing CT and 4DCT average, with or without smoothing, and between the repeated 4DCT scans. HU of −750 and −630 were found to have the greatest transformation-based ventilation for human and sheep subjects, respectively. Maximum Xe-CT derived ventilation was found to locate at HU of −600 in sheep subjects. The curve between Xe-CT ventilation and HU was noisy for tissue above HU −400, possibly due to less intensity change of Xe gas during wash-out and wash-in phases. Conclusion: Both transformation-based and Xe-CT ventilation demonstrated that lung tissues with HU values in the range of (-750, −600) HU have the maximum ventilation potential. The correlation between HU and ventilation suggests that HU might be used to help guide the ventilation calculation and make it more robust to noise and image registration errors. Research support from NIH grants CA166703 and CA166119 and a gift from Roger Koch.

WE-AB-202-06: Correlating Lung CT HU with Transformation-Based and Xe-CT Derived Ventilation

Energy Technology Data Exchange (ETDEWEB)

Du, K; Patton, T; Bayouth, J [University of Wisconsin, Madison, WI (United States); Reinhardt, J; Christensen, G [The University of Iowa, Iowa City, IA (United States)

2016-06-15

Purpose: Regional lung ventilation is useful to reduce radiation-induced function damage during lung cancer radiation therapy. Recently a new direct HU (Hounsfield unit)-based method was proposed to estimate the ventilation potential without image registration. The purpose of this study is to examine if there is a functional dependence between HU values and transformation-based or Xe-CT derived ventilation. Methods: 4DCT images acquired from 13 patients prior to radiation therapy and 4 mechanically ventilated sheep subjects which also have associated Xe-CT images were used for this analysis. Transformation-based ventilation was computed using Jacobian determinant of the transformation field between peak-exhale and peak-inhale 4DCT images. Both transformation and Xe-CT derived ventilation was computed for each HU bin. Color scatter plot and cumulative histogram were used to compare and validate the direct HU-based method. Results: There was little change of the center and shape of the HU histograms between free breathing CT and 4DCT average, with or without smoothing, and between the repeated 4DCT scans. HU of −750 and −630 were found to have the greatest transformation-based ventilation for human and sheep subjects, respectively. Maximum Xe-CT derived ventilation was found to locate at HU of −600 in sheep subjects. The curve between Xe-CT ventilation and HU was noisy for tissue above HU −400, possibly due to less intensity change of Xe gas during wash-out and wash-in phases. Conclusion: Both transformation-based and Xe-CT ventilation demonstrated that lung tissues with HU values in the range of (-750, −600) HU have the maximum ventilation potential. The correlation between HU and ventilation suggests that HU might be used to help guide the ventilation calculation and make it more robust to noise and image registration errors. Research support from NIH grants CA166703 and CA166119 and a gift from Roger Koch.

CFD study of exhaled droplet transmission between occupants under different ventilation strategies in a typical office room

Energy Technology Data Exchange (ETDEWEB)

He, Qibin; Gao, Naiping; Zhu, Tong; Wu, Jiazheng [Institute of Refrigeration and Thermal Engineering, School of Mechanical Engineering, Tongji University, Siping Road 1239, Shanghai (China); Niu, Jianlei [Department of Building Services Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon (China)

2011-02-15

This paper investigated the transmission of respiratory droplets between two seated occupants equipped with one type of personalized ventilation (PV) device using round movable panel (RMP) in an office room. The office was ventilated by three different total volume (TV) ventilation strategies, i.e. mixing ventilation (MV), displacement ventilation (DV), and under-floor air distribution (UFAD) system respectively as background ventilation methods. Concentrations of particles with aerodynamic diameters of 0.8 {mu}m, 5 {mu}m, and 16 {mu}m as well as tracer gas were numerically studied in the Eulerian frame. Two indexes, i.e. intake fraction (IF) and concentration uniformity index R{sub C} were introduced to evaluate the performance of ventilation systems. It was found that without PV, DV performed best concern protecting the exposed manikin from the pollutants exhaled by the polluting manikin. In MV when the exposed manikin opened RMP the inhaled air quality could always be improved. In DV and UFAD application of RMP might sometimes, depending on the personalized airflow rate, increase the exposure of the others to the exhaled droplets of tracer gas, 0.8 {mu}m particles, and 5 {mu}m particles from the infected occupants. Application of PV could reduce R{sub C} for all the three TV systems of 0.8 {mu}m and 5 {mu}m particles. PV enhanced mixing degree of particles under DV and UFAD based conditions much stronger than under MV based ones. PV could increase the average concentration in the occupied zone of the exposed manikin as well as provide clean personalized airflow. Whether inhaled air quality could be improved depended on the balance of pros and cons of PV. (author)

Design and Construction of a Microcontroller-Based Ventilator Synchronized with Pulse Oximeter.

Science.gov (United States)

Gölcük, Adem; Işık, Hakan; Güler, İnan

2016-07-01

This study aims to introduce a novel device with which mechanical ventilator and pulse oximeter work in synchronization. Serial communication technique was used to enable communication between the pulse oximeter and the ventilator. The SpO2 value and the pulse rate read on the pulse oximeter were transmitted to the mechanical ventilator through transmitter (Tx) and receiver (Rx) lines. The fuzzy-logic-based software developed for the mechanical ventilator interprets these values and calculates the percentage of oxygen (FiO2) and Positive End-Expiratory Pressure (PEEP) to be delivered to the patient. The fuzzy-logic-based software was developed to check the changing medical states of patients and to produce new results (FiO2 ve PEEP) according to each new state. FiO2 and PEEP values delivered from the ventilator to the patient can be calculated in this way without requiring any arterial blood gas analysis. Our experiments and the feedbacks from physicians show that this device makes it possible to obtain more successful results when compared to the current practices.

Human Response to Ductless Personalized Ventilation with Local Air Cleaning: Air Quality and Prevalence of SBS Symptoms

DEFF Research Database (Denmark)

Dalewski, Mariusz; Bivolarova, Maria; Fillon, Maelys

2013-01-01

The impact of local air cleaning and cooling of the head region by ductless personalized ventilation (DPV) on perceived air quality (PAQ) and Sick Building Syndrome (SBS) symptoms was studied. Thirty subjects participated in experiments performed in a test room with displacement ventilation (DV...... with air filter and 29 °C with DPV without filter. During the experiments the subjects simulated office work and answered on computerized questionnaires. At warm environment PAQ and air freshness significantly improved when DPV was used. Eye dryness increased significantly with time but was not influenced...... by air temperature and filtering. At 29 °C the facially applied air movement from DPV increased the eye dryness. The SBS symptoms increased with time and were higher (not significantly) at the warm conditions. Air movement did not have profound impact on the SBS symptoms, while filtering had only at 23...

30 CFR 75.324 - Intentional changes in the ventilation system.

Science.gov (United States)

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Intentional changes in the ventilation system... COAL MINE SAFETY AND HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Ventilation § 75.324 Intentional changes in the ventilation system. (a) A person designated by the operator shall supervise any...

Energy and cost associated with ventilating office buildings in a tropical climate.

Science.gov (United States)

Rim, Donghyun; Schiavon, Stefano; Nazaroff, William W

2015-01-01

Providing sufficient amounts of outdoor air to occupants is a critical building function for supporting occupant health, well-being and productivity. In tropical climates, high ventilation rates require substantial amounts of energy to cool and dehumidify supply air. This study evaluates the energy consumption and associated cost for thermally conditioning outdoor air provided for building ventilation in tropical climates, considering Singapore as an example locale. We investigated the influence on energy consumption and cost of the following factors: outdoor air temperature and humidity, ventilation rate (L/s per person), indoor air temperature and humidity, air conditioning system coefficient of performance (COP), and cost of electricity. Results show that dehumidification of outdoor air accounts for more than 80% of the energy needed for building ventilation in Singapore's tropical climate. Improved system performance and/or a small increase in the indoor temperature set point would permit relatively large ventilation rates (such as 25 L/s per person) at modest or no cost increment. Overall, even in a thermally demanding tropical climate, the energy cost associated with increasing ventilation rate up to 25 L/s per person is less than 1% of the wages of an office worker in an advanced economy like Singapore's. This result implies that the benefits of increasing outdoor air ventilation rate up to 25 L/s per person--which is suggested to provide for productivity increases, lower sick building syndrome symptom prevalence, and reduced sick leave--can be much larger than the incremental cost of ventilation.

Improved air ventilation rate estimation based on a statistical model

International Nuclear Information System (INIS)

Brabec, M.; Jilek, K.

2004-01-01

A new approach to air ventilation rate estimation from CO measurement data is presented. The approach is based on a state-space dynamic statistical model, allowing for quick and efficient estimation. Underlying computations are based on Kalman filtering, whose practical software implementation is rather easy. The key property is the flexibility of the model, allowing various artificial regimens of CO level manipulation to be treated. The model is semi-parametric in nature and can efficiently handle time-varying ventilation rate. This is a major advantage, compared to some of the methods which are currently in practical use. After a formal introduction of the statistical model, its performance is demonstrated on real data from routine measurements. It is shown how the approach can be utilized in a more complex situation of major practical relevance, when time-varying air ventilation rate and radon entry rate are to be estimated simultaneously from concurrent radon and CO measurements

Performance analysis of ventilation systems with desiccant wheel cooling based on exergy destruction

International Nuclear Information System (INIS)

Tu, Rang; Liu, Xiao-Hua; Hwang, Yunho; Ma, Fei

2016-01-01

Highlights: • Ventilation systems with desiccant wheel were analyzed from exergy destruction. • Main performances influencing factors for ventilation systems are put forward. • Improved ventilation systems with lower exergy destruction are suggested. • Performances of heat pumps driven ventilation systems are greatly increased. - Abstract: This paper investigates the performances of ventilation systems with desiccant wheel cooling from the perspective of exergy destructions. Based on the inherent influencing factors for exergy destructions of heat and mass transfer and heat sources, provide guidelines for efficient system design. First, performances of a basic ventilation system are simulated, which is operated at high regeneration temperature and low coefficient of performance (COP). Then, exergy analysis of the basic ventilation system shows that exergy destructions mainly exist in the heat and mass transfer components and the heat source. The inherent influencing factors for the heat and mass transfer exergy destruction are heat and mass transfer capacities, which are related to over dehumidification of the desiccant wheel, and unmatched coefficients, which represent the uniformity of the temperature or humidity ratio differences fields for heat and mass transfer components. Based on these findings, two improved ventilation systems are suggested. For the first system, over dehumidification is avoided and unmatched coefficients for each component are reduced. With lower heat and mass transfer exergy destructions and lower regeneration temperature, COP and exergy efficiency of the first system are increased compared with the basic ventilation system. For the second system, a heat pump, which recovers heat from the process air to heat the regeneration air, is adopted to replace the electrical heater and cooling devices. The exergy destruction of the heat pump is considerably reduced as compared with heat source exergy destruction of the basic ventilation

Validation of a Human Exhalation Flow Simulation in a Room with Vertical Ventilation

DEFF Research Database (Denmark)

Olmedo, Inés; Nielsen, Peter V.; Adana, M. Ruiz de

2012-01-01

flow around persons in combination with the surrounding conditions. Analyses of the flow in the room (macroenvironment) show a number of parameters that play an important role in minimising of airborne cross-infection. The air flow rate to the room must be high, and the air distribution pattern can...... be designed to have high ventilation effectiveness. Furthermore, personalized ventilation may reduce the risk of cross-infection. Personalized ventilation can be used especially in hospital wards, aircraft cabins and, in general, where people are located at defined positions. Analyses of the flow...

Investigation of four-dimensional computed tomography-based pulmonary ventilation imaging in patients with emphysematous lung regions

Energy Technology Data Exchange (ETDEWEB)

Yamamoto, Tokihiro; Loo, Billy W Jr; Keall, Paul J [Department of Radiation Oncology, Stanford University School of Medicine, 875 Blake Wilbur Dr, Stanford, CA 94305-5847 (United States); Kabus, Sven; Lorenz, Cristian; Von Berg, Jens; Blaffert, Thomas [Department of Digital Imaging, Philips Research Europe, Roentgenstrasse 24-26, D-22335 Hamburg (Germany); Klinder, Tobias, E-mail: Tokihiro@stanford.edu [Clinical Informatics, Interventional, and Translational Solutions, Philips Research North America, Briarcliff Manor, NY 10510 (United States)

2011-04-07

A pulmonary ventilation imaging technique based on four-dimensional (4D) computed tomography (CT) has advantages over existing techniques. However, physiologically accurate 4D-CT ventilation imaging has not been achieved in patients. The purpose of this study was to evaluate 4D-CT ventilation imaging by correlating ventilation with emphysema. Emphysematous lung regions are less ventilated and can be used as surrogates for low ventilation. We tested the hypothesis: 4D-CT ventilation in emphysematous lung regions is significantly lower than in non-emphysematous regions. Four-dimensional CT ventilation images were created for 12 patients with emphysematous lung regions as observed on CT, using a total of four combinations of two deformable image registration (DIR) algorithms: surface-based (DIR{sup sur}) and volumetric (DIR{sup vol}), and two metrics: Hounsfield unit (HU) change (V{sub HU}) and Jacobian determinant of deformation (V{sub Jac}), yielding four ventilation image sets per patient. Emphysematous lung regions were detected by density masking. We tested our hypothesis using the one-tailed t-test. Visually, different DIR algorithms and metrics yielded spatially variant 4D-CT ventilation images. The mean ventilation values in emphysematous lung regions were consistently lower than in non-emphysematous regions for all the combinations of DIR algorithms and metrics. V{sub HU} resulted in statistically significant differences for both DIR{sup sur} (0.14 {+-} 0.14 versus 0.29 {+-} 0.16, p = 0.01) and DIR{sup vol} (0.13 {+-} 0.13 versus 0.27 {+-} 0.15, p < 0.01). However, V{sub Jac} resulted in non-significant differences for both DIR{sup sur} (0.15 {+-} 0.07 versus 0.17 {+-} 0.08, p = 0.20) and DIR{sup vol} (0.17 {+-} 0.08 versus 0.19 {+-} 0.09, p = 0.30). This study demonstrated the strong correlation between the HU-based 4D-CT ventilation and emphysema, which indicates the potential for HU-based 4D-CT ventilation imaging to achieve high physiologic accuracy. A

An evidence-based recommendation on bed head elevation for mechanically ventilated patients.

Science.gov (United States)

Niël-Weise, Barbara S; Gastmeier, Petra; Kola, Axel; Vonberg, Ralf P; Wille, Jan C; van den Broek, Peterhans J

2011-01-01

A semi-upright position in ventilated patients is recommended to prevent ventilator-associated pneumonia (VAP) and is one of the components in the Ventilator Bundle of the Institute for Health Care Improvement. This recommendation, however, is not an evidence-based one. A systematic review on the benefits and disadvantages of semi-upright position in ventilated patients was done according to PRISMA guidelines. Then a European expert panel developed a recommendation based on the results of the systematic review and considerations beyond the scientific evidence in a three-round electronic Delphi procedure. Three trials (337 patients) were included in the review. The results showed that it was uncertain whether a 45° bed head elevation was effective or harmful with regard to the occurrence of clinically suspected VAP, microbiologically confirmed VAP, decubitus and mortality, and that it was unknown whether 45° elevation for 24 hours a day increased the risk for thromboembolism or hemodynamic instability. A group of 22 experts recommended elevating the head of the bed of mechanically ventilated patients to a 20 to 45° position and preferably to a ≥ 30° position as long as it does not pose risks or conflicts with other nursing tasks, medical interventions or patients' wishes. Although the review failed to prove clinical benefits of bed head elevation, experts prefer this position in ventilated patients. They made clear that the position of a ventilated patient in bed depended on many determinants. Therefore, given the scientific uncertainty about the benefits and harms of a semi-upright position, this position could only be recommended as the preferred position with the necessary restrictions.

30 CFR 57.14213 - Ventilation and shielding for welding.

Science.gov (United States)

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Ventilation and shielding for welding. 57.14213... welding. (a) Welding operations shall be shielded when performed at locations where arc flash could be hazardous to persons. (b) All welding operations shall be well-ventilated. ...

Use of 4-Dimensional Computed Tomography-Based Ventilation Imaging to Correlate Lung Dose and Function With Clinical Outcomes

International Nuclear Information System (INIS)

Vinogradskiy, Yevgeniy; Castillo, Richard; Castillo, Edward; Tucker, Susan L.; Liao, Zhongxing; Guerrero, Thomas; Martel, Mary K.

2013-01-01

Purpose: Four-dimensional computed tomography (4DCT)-based ventilation is an emerging imaging modality that can be used in the thoracic treatment planning process. The clinical benefit of using ventilation images in radiation treatment plans remains to be tested. The purpose of the current work was to test the potential benefit of using ventilation in treatment planning by evaluating whether dose to highly ventilated regions of the lung resulted in increased incidence of clinical toxicity. Methods and Materials: Pretreatment 4DCT data were used to compute pretreatment ventilation images for 96 lung cancer patients. Ventilation images were calculated using 4DCT data, deformable image registration, and a density-change based algorithm. Dose–volume and ventilation-based dose function metrics were computed for each patient. The ability of the dose–volume and ventilation-based dose–function metrics to predict for severe (grade 3+) radiation pneumonitis was assessed using logistic regression analysis, area under the curve (AUC) metrics, and bootstrap methods. Results: A specific patient example is presented that demonstrates how incorporating ventilation-based functional information can help separate patients with and without toxicity. The logistic regression significance values were all lower for the dose–function metrics (range P=.093-.250) than for their dose–volume equivalents (range, P=.331-.580). The AUC values were all greater for the dose–function metrics (range, 0.569-0.620) than for their dose–volume equivalents (range, 0.500-0.544). Bootstrap results revealed an improvement in model fit using dose–function metrics compared to dose–volume metrics that approached significance (range, P=.118-.155). Conclusions: To our knowledge, this is the first study that attempts to correlate lung dose and 4DCT ventilation-based function to thoracic toxicity after radiation therapy. Although the results were not significant at the .05 level, our data suggests

Influence of chest compression artefact on capnogram-based ventilation detection during out-of-hospital cardiopulmonary resuscitation.

Science.gov (United States)

Leturiondo, Mikel; Ruiz de Gauna, Sofía; Ruiz, Jesus M; Julio Gutiérrez, J; Leturiondo, Luis A; González-Otero, Digna M; Russell, James K; Zive, Dana; Daya, Mohamud

2018-03-01

Capnography has been proposed as a method for monitoring the ventilation rate during cardiopulmonary resuscitation (CPR). A high incidence (above 70%) of capnograms distorted by chest compression induced oscillations has been previously reported in out-of-hospital (OOH) CPR. The aim of the study was to better characterize the chest compression artefact and to evaluate its influence on the performance of a capnogram-based ventilation detector during OOH CPR. Data from the MRx monitor-defibrillator were extracted from OOH cardiac arrest episodes. For each episode, presence of chest compression artefact was annotated in the capnogram. Concurrent compression depth and transthoracic impedance signals were used to identify chest compressions and to annotate ventilations, respectively. We designed a capnogram-based ventilation detection algorithm and tested its performance with clean and distorted episodes. Data were collected from 232 episodes comprising 52 654 ventilations, with a mean (±SD) of 227 (±118) per episode. Overall, 42% of the capnograms were distorted. Presence of chest compression artefact degraded algorithm performance in terms of ventilation detection, estimation of ventilation rate, and the ability to detect hyperventilation. Capnogram-based ventilation detection during CPR using our algorithm was compromised by the presence of chest compression artefact. In particular, artefact spanning from the plateau to the baseline strongly degraded ventilation detection, and caused a high number of false hyperventilation alarms. Further research is needed to reduce the impact of chest compression artefact on capnographic ventilation monitoring. Copyright © 2017 Elsevier B.V. All rights reserved.

History of Mechanical Ventilation. From Vesalius to Ventilator-induced Lung Injury.

Science.gov (United States)

Slutsky, Arthur S

2015-05-15

Mechanical ventilation is a life-saving therapy that catalyzed the development of modern intensive care units. The origins of modern mechanical ventilation can be traced back about five centuries to the seminal work of Andreas Vesalius. This article is a short history of mechanical ventilation, tracing its origins over the centuries to the present day. One of the great advances in ventilatory support over the past few decades has been the development of lung-protective ventilatory strategies, based on our understanding of the iatrogenic consequences of mechanical ventilation such as ventilator-induced lung injury. These strategies have markedly improved clinical outcomes in patients with respiratory failure.

Comparison of 4-Dimensional Computed Tomography Ventilation With Nuclear Medicine Ventilation-Perfusion Imaging: A Clinical Validation Study

International Nuclear Information System (INIS)

Vinogradskiy, Yevgeniy; Koo, Phillip J.; Castillo, Richard; Castillo, Edward; Guerrero, Thomas; Gaspar, Laurie E.; Miften, Moyed; Kavanagh, Brian D.

2014-01-01

Purpose: Four-dimensional computed tomography (4DCT) ventilation imaging provides lung function information for lung cancer patients undergoing radiation therapy. Before 4DCT-ventilation can be implemented clinically it needs to be validated against an established imaging modality. The purpose of this work was to compare 4DCT-ventilation to nuclear medicine ventilation, using clinically relevant global metrics and radiologist observations. Methods and Materials: Fifteen lung cancer patients with 16 sets of 4DCT and nuclear medicine ventilation-perfusion (VQ) images were used for the study. The VQ-ventilation images were acquired in planar mode using Tc-99m-labeled diethylenetriamine-pentaacetic acid aerosol inhalation. 4DCT data, spatial registration, and a density-change-based model were used to compute a 4DCT-based ventilation map for each patient. The percent ventilation was calculated in each lung and each lung third for both the 4DCT and VQ-ventilation scans. A nuclear medicine radiologist assessed the VQ and 4DCT scans for the presence of ventilation defects. The VQ and 4DCT-based images were compared using regional percent ventilation and radiologist clinical observations. Results: Individual patient examples demonstrate good qualitative agreement between the 4DCT and VQ-ventilation scans. The correlation coefficients were 0.68 and 0.45, using the percent ventilation in each individual lung and lung third, respectively. Using radiologist-noted presence of ventilation defects and receiver operating characteristic analysis, the sensitivity, specificity, and accuracy of the 4DCT-ventilation were 90%, 64%, and 81%, respectively. Conclusions: The current work compared 4DCT with VQ-based ventilation using clinically relevant global metrics and radiologist observations. We found good agreement between the radiologist's assessment of the 4DCT and VQ-ventilation images as well as the percent ventilation in each lung. The agreement lessened when the data were

A multiscale MDCT image-based breathing lung model with time-varying regional ventilation

Science.gov (United States)

Yin, Youbing; Choi, Jiwoong; Hoffman, Eric A.; Tawhai, Merryn H.; Lin, Ching-Long

2012-01-01

A novel algorithm is presented that links local structural variables (regional ventilation and deforming central airways) to global function (total lung volume) in the lung over three imaged lung volumes, to derive a breathing lung model for computational fluid dynamics simulation. The algorithm constitutes the core of an integrative, image-based computational framework for subject-specific simulation of the breathing lung. For the first time, the algorithm is applied to three multi-detector row computed tomography (MDCT) volumetric lung images of the same individual. A key technique in linking global and local variables over multiple images is an in-house mass-preserving image registration method. Throughout breathing cycles, cubic interpolation is employed to ensure C1 continuity in constructing time-varying regional ventilation at the whole lung level, flow rate fractions exiting the terminal airways, and airway deformation. The imaged exit airway flow rate fractions are derived from regional ventilation with the aid of a three-dimensional (3D) and one-dimensional (1D) coupled airway tree that connects the airways to the alveolar tissue. An in-house parallel large-eddy simulation (LES) technique is adopted to capture turbulent-transitional-laminar flows in both normal and deep breathing conditions. The results obtained by the proposed algorithm when using three lung volume images are compared with those using only one or two volume images. The three-volume-based lung model produces physiologically-consistent time-varying pressure and ventilation distribution. The one-volume-based lung model under-predicts pressure drop and yields un-physiological lobar ventilation. The two-volume-based model can account for airway deformation and non-uniform regional ventilation to some extent, but does not capture the non-linear features of the lung. PMID:23794749

A multiscale MDCT image-based breathing lung model with time-varying regional ventilation

Energy Technology Data Exchange (ETDEWEB)

Yin, Youbing, E-mail: youbing-yin@uiowa.edu [Department of Mechanical and Industrial Engineering, The University of Iowa, Iowa City, IA 52242 (United States); IIHR-Hydroscience and Engineering, The University of Iowa, Iowa City, IA 52242 (United States); Department of Radiology, The University of Iowa, Iowa City, IA 52242 (United States); Choi, Jiwoong, E-mail: jiwoong-choi@uiowa.edu [Department of Mechanical and Industrial Engineering, The University of Iowa, Iowa City, IA 52242 (United States); IIHR-Hydroscience and Engineering, The University of Iowa, Iowa City, IA 52242 (United States); Hoffman, Eric A., E-mail: eric-hoffman@uiowa.edu [Department of Radiology, The University of Iowa, Iowa City, IA 52242 (United States); Department of Biomedical Engineering, The University of Iowa, Iowa City, IA 52242 (United States); Department of Internal Medicine, The University of Iowa, Iowa City, IA 52242 (United States); Tawhai, Merryn H., E-mail: m.tawhai@auckland.ac.nz [Auckland Bioengineering Institute, The University of Auckland, Auckland (New Zealand); Lin, Ching-Long, E-mail: ching-long-lin@uiowa.edu [Department of Mechanical and Industrial Engineering, The University of Iowa, Iowa City, IA 52242 (United States); IIHR-Hydroscience and Engineering, The University of Iowa, Iowa City, IA 52242 (United States)

2013-07-01

A novel algorithm is presented that links local structural variables (regional ventilation and deforming central airways) to global function (total lung volume) in the lung over three imaged lung volumes, to derive a breathing lung model for computational fluid dynamics simulation. The algorithm constitutes the core of an integrative, image-based computational framework for subject-specific simulation of the breathing lung. For the first time, the algorithm is applied to three multi-detector row computed tomography (MDCT) volumetric lung images of the same individual. A key technique in linking global and local variables over multiple images is an in-house mass-preserving image registration method. Throughout breathing cycles, cubic interpolation is employed to ensure C{sub 1} continuity in constructing time-varying regional ventilation at the whole lung level, flow rate fractions exiting the terminal airways, and airway deformation. The imaged exit airway flow rate fractions are derived from regional ventilation with the aid of a three-dimensional (3D) and one-dimensional (1D) coupled airway tree that connects the airways to the alveolar tissue. An in-house parallel large-eddy simulation (LES) technique is adopted to capture turbulent-transitional-laminar flows in both normal and deep breathing conditions. The results obtained by the proposed algorithm when using three lung volume images are compared with those using only one or two volume images. The three-volume-based lung model produces physiologically-consistent time-varying pressure and ventilation distribution. The one-volume-based lung model under-predicts pressure drop and yields un-physiological lobar ventilation. The two-volume-based model can account for airway deformation and non-uniform regional ventilation to some extent, but does not capture the non-linear features of the lung.

Use of personalized ventilation for improving health, comfort, and performance at high room temperature and humidity

DEFF Research Database (Denmark)

Melikov, Arsen Krikor; Skwarczynski, Mariusz; Kaczmarczyk, J.

2013-01-01

in five 4-h experiments in a climate chamber. Under the conditions with PV, the subjects were able to control the rate and direction of the supplied personalized flow of clean air. Subjective responses were collected through questionnaires. During all exposures, the subjects were occupied with tasks used......The effect of personalized ventilation (PV) on people's health, comfort, and performance in a warm and humid environment (26 and 28°C at 70% relative humidity) was studied and compared with their responses in a comfortable environment (23°C and 40% relative humidity). Thirty subjects participated...... to assess their performance. Objective measures of tear film stability, concentration of stress biomarkers in saliva, and eye blinking rate were taken. Using PV significantly improved the perceived air quality (PAQ) and thermal sensation and decreased the intensity of Sick Building Syndrome (SBS) symptoms...

Ventilation area measured with eit in order to optimize peep settings in mechanically ventilated patients

NARCIS (Netherlands)

Blankman, P; Groot Jebbink, E; Preis, C; Bikker, I.; Gommers, D.

2012-01-01

INTRODUCTION. Electrical Impedance Tomography (EIT) is a non-invasive imaging technique, which can be used to visualize ventilation. Ventilation will be measured by impedance changes due to ventilation. OBJECTIVES. The aim of this study was to optimize PEEP settings based on the ventilation area of

A java based simulator with user interface to simulate ventilated patients

Directory of Open Access Journals (Sweden)

Stehle P.

2015-09-01

Full Text Available Mechanical ventilation is a life-saving intervention, which despite its use on a routine basis, poses the risk of inflicting further damage to the lung tissue if ventilator settings are chosen inappropriately. Medical decision support systems may help to prevent such injuries while providing the optimal settings to reach a defined clinical goal. In order to develop and verify decision support algorithms, a test bench simulating a patient’s behaviour is needed. We propose a Java based system that allows simulation of respiratory mechanics, gas exchange and cardiovascular dynamics of a mechanically ventilated patient. The implemented models are allowed to interact and are interchangeable enabling the simulation of various clinical scenarios. Model simulations are running in real-time and show physiologically plausible results.

Ventilation

DEFF Research Database (Denmark)

Nielsen, Toke Rammer; Svendsen, Sv Aa Højgaard

1999-01-01

The note concerns ventilation in residential buildings. Describes components in ventilation systems, electric energy consumption and different ventilation systems with heat exchanger.......The note concerns ventilation in residential buildings. Describes components in ventilation systems, electric energy consumption and different ventilation systems with heat exchanger....

: ventilators for noninvasive ventilation

OpenAIRE

Fauroux , Brigitte; Leroux , Karl; Desmarais , Gilbert; Isabey , Daniel; Clément , Annick; Lofaso , Frédéric; Louis , Bruno

2008-01-01

International audience; The aim of the present study was to evaluate the performance characteristics of all the ventilators proposed for home noninvasive positive-pressure ventilation in children in France. The ventilators (one volume-targeted, 12 pressure-targeted and four dual) were evaluated on a bench which simulated six different paediatric ventilatory patterns. For each ventilator, the quality of the inspiratory and expiratory trigger and the ability to reach and maintain the preset pre...

Assessment of ventilation and indoor air pollutants in nursery and elementary schools in France.

Science.gov (United States)

Canha, N; Mandin, C; Ramalho, O; Wyart, G; Ribéron, J; Dassonville, C; Hänninen, O; Almeida, S M; Derbez, M

2016-06-01

The aim of this study was to characterize the relationship between Indoor Air Quality (IAQ) and ventilation in French classrooms. Various parameters were measured over one school week, including volatile organic compounds, aldehydes, particulate matter (PM2.5 mass concentration and number concentration), carbon dioxide (CO2 ), air temperature, and relative humidity in 51 classrooms at 17 schools. The ventilation was characterized by several indicators, such as the air exchange rate, ventilation rate (VR), and air stuffiness index (ICONE), that are linked to indoor CO2 concentration. The influences of the season (heating or non-heating), type of school (nursery or elementary), and ventilation on the IAQ were studied. Based on the minimum value of 4.2 l/s per person required by the French legislation for mechanically ventilated classrooms, 91% of the classrooms had insufficient ventilation. The VR was significantly higher in mechanically ventilated classrooms compared with naturally ventilated rooms. The correlations between IAQ and ventilation vary according to the location of the primary source of each pollutant (outdoor vs. indoor), and for an indoor source, whether it is associated with occupant activity or continuous emission. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Assessment of the effectiveness of ventilation types for reducing the occupational exposure to bioaerosols in health care staffs

Directory of Open Access Journals (Sweden)

Mohammad Javad Jafari

2015-11-01

Full Text Available Background & Objectives : Hospital indoor air contains a wide range of airborne pathogenic bioaerosols which have a significant impact on health care staff’ health and welfare. The aim of this study was to assess the effects of ventilation system types on occupational exposure of the health care staffs to airborne bioaerosols in the isolation room based on the patient bed arrangements and the standing locations of the health care staff. Methods: Personal exposures were measured based on five given types of ventilation system, 2 patient bed arrangements (at a corner and in the middle of the room, and two different standing locations for the health care staff (standing close to the patient’s bed, and down a side section of the bed. For personal sampling, filtration method recommended by th e American conference of governmental industrial hygienists(ACGIH was used. Result: The highest exposure to airborne bioaerosols was observed when the ventilation system was switched off. There were significant decreases in the bioaerosols concentration after using all types of ventilation system (P value 0.05. Conclusions : The most effective ventilation system for decreasing health care staff’ exposures in the isolation room was associated with supplying of air from a circular grill located on the northern wall and exhausting it through a linear slot located on the southern wall (type 1 with the ventilation rate of 12 air changes per hour.

Control of the Free Convective Flow around the Human Body for Enhanced Inhaled Air Quality: Application to a Seat-Incorporated Personalized Ventilation Unit

DEFF Research Database (Denmark)

Bolashikov, Zhecho Dimitrov; Melikov, Arsen Krikor; Krenek, M.

2010-01-01

This paper reports on methods for control of the free convective flow around the human body, with the aim of improving inhaled air quality. The methods were studied with sea-incorporated personalized ventilation (PV)-two PV nozzles placed sideways at the head level of a seated occupant supplied...

SUPRAGLOTTIC JET VENTILATION VERSUS CONVENTIONAL ENDOTRACHEAL VENTILATION IN MINOR LARYNGEAL SURGERIES

Directory of Open Access Journals (Sweden)

Illendual Upendranath

2016-08-01

Full Text Available Any attempt at intubation will cause many cardiovascular responses and the major concern during this time is to attenuate the same. Similar response is seen during procedures on Larynx in microlaryngeal surgery which produces an intense cardiovascular stimulation during suspension laryngoscopy and intubation. AIM OF STUDY Supraglottic jet ventilation versus conventional endotracheal ventilation in minor laryngeal surgeries. To evaluate the haemodynamic response in supraglottic jet ventilation and conventional intubation in minor laryngeal surgeries. METHODS Patients were randomised to 2 Groups: 30 patients in each group; Group A - in whom supraglottic jet ventilation was planned and Group B - in whom endotracheal intubation was planned. RESULT The haemodynamic response in terms of increase in MAP and HR is significantly more with endotracheal intubation than with supraglottic jet ventilation. CONCLUSION Our study showed that supraglottic jet ventilation showed a better haemodynamic stability when compared to conventional endotracheal intubation in patients undergoing minor laryngeal surgeries. Statistical scores were also in favour of the patients treated with supraglottic jet ventilation based on the p values.

Why We Ventilate

Energy Technology Data Exchange (ETDEWEB)

Logue, Jennifer M.; Sherman, Max H.; Price, Phil N.; Singer, Brett C.

2011-09-01

It is widely accepted that ventilation is critical for providing good indoor air quality (IAQ) in homes. However, the definition of"good" IAQ, and the most effective, energy efficient methods for delivering it are still matters of research and debate. This paper presents the results of work done at the Lawrence Berkeley National Lab to identify the air pollutants that drive the need for ventilation as part of a larger effort to develop a health-based ventilation standard. First, we present results of a hazard analysis that identified the pollutants that most commonly reach concentrations in homes that exceed health-based standards or guidelines for chronic or acute exposures. Second, we present results of an impact assessment that identified the air pollutants that cause the most harm to the U.S. population from chronic inhalation in residences. Lastly, we describe the implications of our findings for developing effective ventilation standards.

Improved regression models for ventilation estimation based on chest and abdomen movements

International Nuclear Information System (INIS)

Liu, Shaopeng; Gao, Robert; He, Qingbo; Staudenmayer, John; Freedson, Patty

2012-01-01

Non-invasive estimation of minute ventilation is important for quantifying the intensity of physical activity of individuals. In this paper, several improved regression models are presented, based on the measurement of chest and abdomen movements from sensor belts worn by subjects (n = 50) engaged in 14 types of physical activity. Five linear models involving a combination of 11 features were developed, and the effects of different model training approaches and window sizes for computing the features were investigated. The performance of the models was evaluated using experimental data collected during the physical activity protocol. The predicted minute ventilation was compared to the criterion ventilation measured using a bidirectional digital volume transducer housed in a respiratory gas exchange system. The results indicate that the inclusion of breathing frequency and the use of percentile points instead of interdecile ranges over a 60 s window size reduced error by about 43%, when applied to the classical two-degrees-of-freedom model. The mean percentage error of the minute ventilation estimated for all the activities was below 7.5%, verifying reasonably good performance of the models and the applicability of the wearable sensing system for minute ventilation estimation during physical activity. (paper)

Concentration Distribution in a Mixing Ventilated Room

DEFF Research Database (Denmark)

Jensen, Rasmus Lund; Pedersen, D.N.; Nielsen, Peter V.

2001-01-01

Today there is an increasing focus on the importance of a proper ventilation system to obtain good working conditions in the term of air and thermal quality to ensure high productivity. Different ventilation principles are used, e.g., mixing ventilation and displacement ventilation. In order...... that the air is fully mixed. The objective of this work is to determine the influence of the location of a pollutant, temperature differences and whether the room is furnished or not. It is also investigated if it is sufficient to determine the mean concentration in the room to determine the personal exposure....... Full scale experiments along with a breathing thermal manikin (BTM) have been used. The results show that the location of the sources is of great importance, just as well as temperature differences. Furthermore, the concentration in the breathing zone showed large differences throughout the room....

Appointment, qualifications and responsibilities of ventilation officers

International Nuclear Information System (INIS)

1981-01-01

The Code provides for the appointment of a ventilation officer when required by the appropriate authority. This guideline offers comment on the appointment, qualifications, training and responsibilities of that person

Helical Tomotherapy Planning for Lung Cancer Based on Ventilation Magnetic Resonance Imaging

Energy Technology Data Exchange (ETDEWEB)

Cai Jing; McLawhorn, Robert [Department of Radiation Oncology, University of Virginia, Charlottesville, VA (United States); Altes, Tallisa A.; Lange, Eduard de [Department of Radiology, University of Virginia, Charlottesville, VA (United States); Read, Paul W.; Larner, James M.; Benedict, Stanley H. [Department of Radiation Oncology, University of Virginia, Charlottesville, VA (United States); Sheng Ke, E-mail: ks2mc@virginia.edu [Department of Radiation Oncology, University of Virginia, Charlottesville, VA (United States)

2011-01-01

To investigate the feasibility of lung ventilation-based treatment planning, computed tomography and hyperpolarized (HP) helium-3 (He-3) magnetic resonance imaging (MRI) ventilation images of 6 subjects were coregistered for intensity-modulated radiation therapy planning in Tomotherapy. Highly-functional lungs (HFL) and less-functional lungs (LFL) were contoured based on their ventilation image intensities, and a cylindrical planning-target-volume was simulated at locations adjacent to both HFL and LFL. Annals of an anatomy-based plan (Plan 1) and a ventilation-based plan (Plan 2) were generated. The following dosimetric parameters were determined and compared between the 2 plans: percentage of total/HFL volume receiving {>=}20 Gy, 15 Gy, 10 Gy, and 5 Gy (TLV{sub 20}, HFLV{sub 20}, TLV{sub 15}, HFLV{sub 15}, TLV{sub 10}, HFLV{sub 10}, TLV{sub 5}, HFLV{sub 5}), mean total/HFL dose (MTLD/HFLD), maximum doses to all organs at risk (OARs), and target dose conformality. Compared with Plan 1, Plan 2 reduced mean HFLD (mean reduction, 0.8 Gy), MTLD (mean reduction, 0.6 Gy), HFLV{sub 20} (mean reduction, 1.9%), TLV{sub 20} (mean reduction, 1.5%), TLV{sub 15} (mean reduction, 1.7%), and TLV{sub 10} (mean reduction, 2.1%). P-values of the above comparisons are less than 0.05 using the Wilcoxon signed rank test. For HFLV{sub 15}, HFLV{sub 10}, TLV{sub 5}, and HTLV{sub 5}, Plan 2 resulted in lower values than plan 1 but the differences are not significant (P-value range, 0.063-0.219). Plan 2 did not significantly change maximum doses to OARs (P-value range, 0.063-0.563) and target conformality (P = 1.000). HP He-3 MRI of patients with lung disease shows a highly heterogeneous ventilation capacity that can be utilized for functional treatment planning. Moderate but statistically significant improvements in sparing functional lungs were achieved using helical tomotherapy plans.

Amyotrophic lateral sclerosis and assisted ventilation: how patients decide.

Science.gov (United States)

Lemoignan, Josée; Ells, Carolyn

2010-06-01

Throughout the course of their illness, people with amyotrophic lateral sclerosis (ALS) must make many treatment decisions; however, none has such a significant impact on quality of life and survival as decisions about assisted ventilation. The purpose of this study was to better understand the experience of decision-making about assisted ventilation for ALS patients. Using qualitative phenomenology methodology, 10 semi-structured interviews were conducted with persons with ALS and their caregivers to elicit factors that are pertinent to their decision-making process about assisted ventilation. Six main themes emerged from the interviews. (1) the meaning of the intervention - participants made a sharp distinction between non-invasive ventilation, which they viewed as a means to relieve symptoms of respiratory failure, and invasive ventilation, which they viewed as taking over their breathing and thereby saving their life when they otherwise would die, (2) the importance of context - including functional status, available supports, and financial implications, (3) the importance of values - with respect to communication, relationships, autonomy, life, and quality of life, (4) the effect of fears - particularly respiratory distress, chocking, running out of air, and the process of death itself, (5) the need for information - how use of assisted ventilation would impact daily life, how death from respiratory failure would occur, how caregivers and persons with ALS differ in their information needs and common misconceptions, and (6) adaptation to or acceptance of the intervention - a lengthy process that involved gradual familiarization with the equipment and its benefits. People with ALS and caregivers value autonomy in decision-making about assisted ventilation. Their decision-making process is neither wholly rational nor self-interested, and includes factors that health professionals should anticipate and address. Discussions about assisted ventilation and timing

Clinical challenges in mechanical ventilation.

Science.gov (United States)

Goligher, Ewan C; Ferguson, Niall D; Brochard, Laurent J

2016-04-30

Mechanical ventilation supports gas exchange and alleviates the work of breathing when the respiratory muscles are overwhelmed by an acute pulmonary or systemic insult. Although mechanical ventilation is not generally considered a treatment for acute respiratory failure per se, ventilator management warrants close attention because inappropriate ventilation can result in injury to the lungs or respiratory muscles and worsen morbidity and mortality. Key clinical challenges include averting intubation in patients with respiratory failure with non-invasive techniques for respiratory support; delivering lung-protective ventilation to prevent ventilator-induced lung injury; maintaining adequate gas exchange in severely hypoxaemic patients; avoiding the development of ventilator-induced diaphragm dysfunction; and diagnosing and treating the many pathophysiological mechanisms that impair liberation from mechanical ventilation. Personalisation of mechanical ventilation based on individual physiological characteristics and responses to therapy can further improve outcomes. Copyright © 2016 Elsevier Ltd. All rights reserved.

Optimization of Occupancy Based Demand Controlled Ventilation in Residences

DEFF Research Database (Denmark)

Mortensen, Dorthe Kragsig; Walker, Iain; Sherman, Max

2011-01-01

Although it has been used for many years in commercial buildings, the application of demand controlled ventilation in residences is limited. In this study we used occupant exposure to pollutants integrated over time (referred to as "dose") as the metric to evaluate the effectiveness and air quality...... implications of demand controlled ventilation in residences. We looked at air quality for two situations. The first is that typically used in ventilation standards: the exposure over a long term. The second is to look at peak exposures that are associated with time variations in ventilation rates and pollutant...... when occupied. We used analytical solutions to the continuity equation to determine the ventilation effectiveness and the long-term chronic dose and peak acute exposure for a representative range of occupancy periods, pollutant generation rates and airflow rates. The results of the study showed that we...

Analysis on ventilation pressure of fire area in longitudinal ventilation of underground tunnel

Science.gov (United States)

Li, Jiaxin; Li, Yanfeng; Feng, Xiao; Li, Junmei

2018-03-01

In order to solve the problem of ventilation pressure loss in the fire area under the fire condition, the wind pressure loss model of the fire area is established based on the thermodynamic equilibrium relation. The semi-empirical calculation formula is obtained by using the model experiment and CFD simulation. The validity of the formula is verified. The results show that the ventilation pressure loss in the fire zone is proportional to the convective heat release rate at the critical velocity, which is inversely proportional to the upstream ventilation velocity and the tunnel cross-sectional area. The proposed formula is consistent with the law of the tunnel fire test fitting formula that results are close, in contrast, the advantage lies in a clear theoretical basis and ventilation velocity values. The resistance of road tunnel ventilation system is calculated accurately and reliably, and then an effective emergency ventilation operation program is developed. It is necessary to consider the fire zone ventilation pressure loss. The proposed ventilation pressure loss formula can be used for design calculation after thorough verification.

Thermal Plumes in Ventilated Rooms

DEFF Research Database (Denmark)

Kofoed, P.; Nielsen, Peter Vilhelm

The main objective of ventilation is to provide good air quality for the occupants. For this purpose the necessary ventilating air change rate must be determined. Within displacement ventilation the estimation is closely related to the air flow rate in the thermal plumes when an air quality based...

Ventilator-driven xenon ventilation studies

International Nuclear Information System (INIS)

Chilcoat, R.T.; Thomas, F.D.; Gerson, J.I.

1984-01-01

A modification of a common commercial Xe-133 ventilation device is described for mechanically assisted ventilation imaging. The patient's standard ventilator serves as the power source controlling the ventilatory rate and volume during the xenon study, but the gases in the two systems are not intermixed. This avoids contamination of the ventilator with radioactive xenon. Supplemental oxygen and positive end-expiratory pressure (PEEP) are provided if needed. The system can be converted quickly for conventional studies with spontaneous respiration

Energy efficient ventilation based on demand humidity control. Demonstration project with 49 apartments in Soenderborg

Energy Technology Data Exchange (ETDEWEB)

NONE

1996-09-01

The aim of the project is to demonstrate how the overall energy consumption in apartment buildings can be reduced through a combination of: 1) Energy efficient ventilation based on demand humidity control; 2) Energy efficient design of the building shell including passive solar and seasonally flexible sunspaces; 3) Use of low temperature heating system. The 3 blocks in the project, each with 16 apartments, are furnished with 3 different ventilation systems: 1) Standard exhaust system according to building codes; 2) Ventilation system with humidity control. Each room is furnished with an air inlet valve controlled by a processor, which monitors the humidity; 3) Standard ventilation system with heat recovery. (au)

Demand Controlled Ventilation and Classroom Ventilation

Energy Technology Data Exchange (ETDEWEB)

Fisk, William J. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Mendell, Mark J. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Davies, Molly [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Eliseeva, Ekaterina [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Faulkner, David [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Hong, Tienzen [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Sullivan, Douglas P. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

2012-05-01

This document summarizes a research effort on demand controlled ventilation and classroom ventilation. The research on demand controlled ventilation included field studies and building energy modeling.

Demand controlled ventilation and classroom ventilation

Energy Technology Data Exchange (ETDEWEB)

Fisk, William J. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Mendell, Mark J. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Davies, Molly [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Eliseeva, Ekaterina [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Faulkner, David [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Hong, Tienzen [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Sullivan, Douglas P. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

2014-01-06

This document summarizes a research effort on demand controlled ventilation and classroom ventilation. The research on demand controlled ventilation included field studies and building energy modeling.

MEASUREMENT OF FRICTIONAL PRESSURE DIFFERENTIALS DURING A VENTILATION SURVEY

International Nuclear Information System (INIS)

B.S. Prosser, PE; I.M. Loomis, PE, PhD

2003-01-01

During the course of a ventilation survey, both airflow quantity and frictional pressure losses are measured and quantified. The measurement of airflow has been extensively studied as the vast majority of ventilation standards/regulations are tied to airflow quantity or velocity. However, during the conduct of a ventilation survey, measurement of airflow only represents half of the necessary parameters required to directly calculate the airway resistance. The measurement of frictional pressure loss is an often misunderstood and misapplied part of the ventilation survey. This paper compares the two basic methods of frictional pressure drop measurements; the barometer and the gauge and tube. Personal experiences with each method will be detailed along with the authors' opinions regarding the applicability and conditions favoring each method

Development of a plastic rotary heat exchanger for room-based ventilation in existing apartments

DEFF Research Database (Denmark)

Smith, Kevin Michael; Svendsen, Svend

2015-01-01

The existing building stock will likely undergo widespread energy renovations to meet future emissions targets. Single-room ventilation may enable the process due to its simple installation, low fan power, and potential for local heat recovery. A short plastic rotary heat exchanger is developed...... for single-room ventilation based on thermal design theory. Performance is predicted from correlations of dimensionless groups for regenerative heat exchangers, and this guides the selection of a polycarbonate honeycomb with small circular channels. Experiments quantify flows and determine temperature...... efficiencies at several ventilation rates while accounting for heat gains from motors and air leakage. The measured and modelled temperature efficiencies show adequate agreement and exceed 80% for a balanced nominal ventilation rate of 28m3/h. This result meets the development criteria but cannot validate...

Evaluation of ventilators for mouthpiece ventilation in neuromuscular disease.

Science.gov (United States)

Khirani, Sonia; Ramirez, Adriana; Delord, Vincent; Leroux, Karl; Lofaso, Frédéric; Hautot, Solène; Toussaint, Michel; Orlikowski, David; Louis, Bruno; Fauroux, Brigitte

2014-09-01

Daytime mouthpiece ventilation is a useful adjunct to nocturnal noninvasive ventilation (NIV) in patients with neuromuscular disease. The aims of the study were to analyze the practice of mouthpiece ventilation and to evaluate the performance of ventilators for mouthpiece ventilation. Practice of mouthpiece ventilation was assessed by a questionnaire, and the performance of 6 home ventilators with mouthpiece ventilation was assessed in a bench test using 24 different conditions per ventilator: 3 mouthpieces, a child and an adult patient profile, and 4 ventilatory modes. Questionnaires were obtained from 30 subjects (mean age 33 ± 11 y) using NIV for 12 ± 7 y. Fifteen subjects used NIV for > 20 h/day, and 11 were totally ventilator-dependent. The subject-reported benefits of mouthpiece ventilation were a reduction in dyspnea (73%) and fatigue (93%) and an improvement in speech (43%) and eating (27%). The bench study showed that none of the ventilators, even those with mouthpiece ventilation software, were able to deliver mouthpiece ventilation without alarms and/or autotriggering in each condition. Alarms and/or ineffective triggering or autotriggering were observed in 135 of the 198 conditions. The occurrence of alarms was more common with a large mouthpiece without a filter compared to a small mouthpiece with a filter (P ventilator. Subjects are satisfied with mouthpiece ventilation. Alarms are common with home ventilators, although less common in those with mouthpiece ventilation software. Improvements in home ventilators are needed to facilitate the expansion of mouthpiece ventilation. Copyright © 2014 by Daedalus Enterprises.

Newer nonconventional modes of mechanical ventilation

Directory of Open Access Journals (Sweden)

Preet Mohinder Singh

2014-01-01

Full Text Available The conventional modes of ventilation suffer many limitations. Although they are popularly used and are well-understood, often they fail to match the patient-based requirements. Over the years, many small modifications in ventilators have been incorporated to improve patient outcome. The ventilators of newer generation respond to patient′s demands by additional feedback systems. In this review, we discuss the popular newer modes of ventilation that have been accepted in to clinical practice. Various intensive care units over the world have found these modes to improve patient ventilator synchrony, decrease ventilator days and improve patient safety. The various modes discusses in this review are: Dual control modes (volume assured pressure support, volume support, Adaptive support ventilation, proportional assist ventilation, mandatory minute ventilation, Bi-level airway pressure release ventilation, (BiPAP, neurally adjusted ventilatory assist and NeoGanesh. Their working principles with their advantages and clinical limitations are discussed in brief.

Mechanical ventilation strategies.

Science.gov (United States)

Keszler, Martin

2017-08-01

Although only a small proportion of full term and late preterm infants require invasive respiratory support, they are not immune from ventilator-associated lung injury. The process of lung damage from mechanical ventilation is multifactorial and cannot be linked to any single variable. Atelectrauma and volutrauma have been identified as the most important and potentially preventable elements of lung injury. Respiratory support strategies for full term and late preterm infants have not been as thoroughly studied as those for preterm infants; consequently, a strong evidence base on which to make recommendations is lacking. The choice of modalities of support and ventilation strategies should be guided by the specific underlying pathophysiologic considerations and the ventilatory approach must be individualized for each patient based on the predominant pathophysiology at the time. Copyright © 2017 Elsevier Ltd. All rights reserved.

Cost-benefit of ventilation and averted radon in dwellings

International Nuclear Information System (INIS)

Katona, T.; Kanyar, B.

2003-01-01

To assess an economically optimal ventilation rate we have introduced a cost-benefit analysis taking into account the cost of heating and benefit of averted dose due to ventilation. The cost of heating due to the elevated ventilation for mitigation of radon content in dwellings can be compensated by the monetary benefit of the averted dose, in case of higher (annually 3-10 mSv) exposure. During the heating season the economically optimal ventilation takes 0.1-0.5 h -1 , meanwhile the radon concentration in the indoor air decreases to 200-800 Bq/m 3 , depending on the exhalation of radon, number of persons living in the dwellings and other local parameters. Our results from the optimal planning correspond to the radon concentrations recommended by the international organizations as action levels. In general, the periodic ventilation in daytime provides a higher averted dose than the constant one in case of the same heating cost. (authors)

[Mechanical ventilation in acute asthma crisis].

Science.gov (United States)

Barbas, Carmen Sílvia Valente; Pinheiro, Bruno do Valle; Vianna, Arthur; Magaldi, Ricardo; Casati, Ana; José, Anderson; Okamoto, Valdelis Novis

2007-06-01

The II Brazilian Consensus Conference on Mechanical Ventilation was published in 2000. Knowledge on the field of mechanical ventilation evolved rapidly since then, with the publication of numerous clinical studies with potential impact on the ventilatory management of critically ill patients. Moreover, the evolving concept of evidence - based medicine determined the grading of clinical recommendations according to the methodological value of the studies on which they are based. This explicit approach has broadened the understanding and adoption of clinical recommendations. For these reasons, AMIB - Associação de Medicina Intensiva Brasileira and SBPT - Sociedade Brasileira de Pneumologia e Tisiologia - decided to update the recommendations of the II Brazilian Consensus. Mechanical ventilation in the asthma attack has been one of the updated topics. Describe the most important topics on the mechanical ventilation during the asthma attack and suggest the main therapeutic approaches. Systematic review of the published literature and gradation of the studies in levels of evidence, using the key words "mechanical ventilation" and "asthma". We present recommendations on the ventilatory modes and settings to be adopted when ventilating a patient during an asthma attack, as well as the recommended monitoring. Alternative ventilation techniques are also presented. Protective ventilatory strategies are recommended when ventilating a patient during a severe asthma attack.

Bench performance of ventilators during simulated paediatric ventilation.

Science.gov (United States)

Park, M A J; Freebairn, R C; Gomersall, C D

2013-05-01

This study compares the accuracy and capabilities of various ventilators using a paediatric acute respiratory distress syndrome lung model. Various compliance settings and respiratory rate settings were used. The study was done in three parts: tidal volume and FiO2 accuracy; pressure control accuracy and positive end-expiratory pressure (PEEP) accuracy. The parameters set on the ventilator were compared with either or both of the measured parameters by the test lung and the ventilator. The results revealed that none of the ventilators could consistently deliver tidal volumes within 1 ml/kg of the set tidal volume, and the discrepancy between the delivered volume and the volume measured by the ventilator varied greatly. The target tidal volume was 8 ml/kg, but delivered tidal volumes ranged from 3.6-11.4 ml/kg and the volumes measured by the ventilator ranged from 4.1-20.6 ml/kg. All the ventilators maintained pressure within 20% of the set pressure, except one ventilator which delivered pressures of up to 27% higher than the set pressure. Two ventilators maintained PEEP within 10% of the prescribed PEEP. The majority of the readings were also within 10%. However, three ventilators delivered, at times, PEEPs over 20% higher. In conclusion, as lung compliance decreases, especially in paediatric patients, some ventilators perform better than others. This study highlights situations where ventilators may not be able to deliver, nor adequately measure, set tidal volumes, pressure, PEEP or FiO2.

Numerical investigation of diffuse ceiling ventilation in an office under different operating conditions

DEFF Research Database (Denmark)

Hviid, Christian Anker; Petersen, Steffen

2014-01-01

is a numerical study of the performance of a six person office equipped with diffuse ventilation ceiling. In total six extreme, yet realistic, operation scenarios were simulated to study the performance including different occupancy, ventilation rates and supply air temperatures. The performance was studied...

Positional effects on distribution of ventilation in chronic obstructive pulmonary disease

International Nuclear Information System (INIS)

Shim, C.; Chun, K.J.; Williams, M.H. Jr.; Blaufox, M.D.

1986-01-01

Ventilation is distributed predominantly to the dependent lung in normal persons in the decubitus position. We evaluated the distribution of ventilation in four patients with mild-to-moderate chronic obstructive pulmonary disease using 81mKr gas. Patients were tested in the sitting and right and left decubitus positions with and without the application of positive end expiratory pressure (PEEP). In contrast to findings in controls, ventilation was predominantly distributed to the nondependent lung in patients in the decubitus position. Mean ventilation in the right lung decreased from 51% of the total in the sitting position to 31% in the right decubitus position; it increased with the application of 10 cm PEEP. Reduced ventilation in the dependent lung most likely is caused by closure of the airways after a decrease in volume. Application of PEEP resulted in increased lung volume and preferential distribution of ventilation to the dependent lung

Summary of human responses to ventilation

Energy Technology Data Exchange (ETDEWEB)

Seppanen, Olli A.; Fisk, William J.

2004-06-01

The effects of ventilation on indoor air quality and health is a complex issue. It is known that ventilation is necessary to remove indoor generated pollutants from indoor air or dilute their concentration to acceptable levels. But, as the limit values of all pollutants are not known, the exact determination of required ventilation rates based on pollutant concentrations and associated risks is seldom possible. The selection of ventilation rates has to be based also on epidemiological research (e.g. Seppanen et al., 1999), laboratory and field experiments (e.g. CEN 1996, Wargocki et al., 2002a) and experience (e.g. ECA 2003). Ventilation may also have harmful effects on indoor air quality and climate if not properly designed, installed, maintained and operated as summarized by Seppdnen (2003). Ventilation may bring indoors harmful substances that deteriorate the indoor environment. Ventilation also affects air and moisture flow through the building envelope and may lead to moisture problems that deteriorate the structures of the building. Ventilation changes the pressure differences over the structures of building and may cause or prevent the infiltration of pollutants from structures or adjacent spaces. Ventilation is also in many cases used to control the thermal environment or humidity in buildings. Ventilation can be implemented with various methods which may also affect health (e.g. Seppdnen and Fisk, 2002, Wargocki et al., 2002a). In non residential buildings and hot climates, ventilation is often integrated with air-conditioning which makes the operation of ventilation system more complex. As ventilation is used for many purposes its health effects are also various and complex. This paper summarizes the current knowledge on positive and negative effects of ventilation on health and other human responses. The focus of the paper is on office-type working environment and residential buildings. In the industrial premises the problems of air quality are usually

Effects of ventilation rate per person and per floor area on perceived air quality, sick building syndrome symptoms, and decision-making.

Science.gov (United States)

Maddalena, R; Mendell, M J; Eliseeva, K; Chan, W R; Sullivan, D P; Russell, M; Satish, U; Fisk, W J

2015-08-01

Ventilation rates (VRs) in buildings must adequately control indoor levels of pollutants; however, VRs are constrained by the energy costs. Experiments in a simulated office assessed the effects of VR per occupant on perceived air quality (PAQ), Sick Building Syndrome (SBS) symptoms, and decision-making performance. A parallel set of experiments assessed the effects of VR per unit floor area on the same outcomes. Sixteen blinded healthy young adult subjects participated in each study. Each exposure lasted four hours and each subject experienced two conditions in a within-subject study design. The order of presentation of test conditions, day of testing, and gender were balanced. Temperature, relative humidity, VRs, and concentrations of pollutants were monitored. Online surveys assessed PAQ and SBS symptoms and a validated computer-based tool measured decision-making performance. Neither changing the VR per person nor changing the VR per floor area, had consistent statistically significant effects on PAQ or SBS symptoms. However, reductions in either occupant-based VR or floor-area-based VR had a significant and independent negative impact on most decision-making measures. These results indicate that the changes in VR employed in the study influence performance of healthy young adults even when PAQ and SBS symptoms are unaffected. The study results indicate the importance of avoiding low VRs per person and low VRs per floor area to minimize decrements in cognitive performance. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

A NEW EXHAUST VENTILATION SYSTEM DESIGN SOFTWARE

Directory of Open Access Journals (Sweden)

H. Asilian Mahabady

2007-09-01

Full Text Available A Microsoft Windows based ventilation software package is developed to reduce time-consuming and boring procedure of exhaust ventilation system design. This program Assure accurate and reliable air pollution control related calculations. Herein, package is tentatively named Exhaust Ventilation Design Software which is developed in VB6 programming environment. Most important features of Exhaust Ventilation Design Software that are ignored in formerly developed packages are Collector design and fan dimension data calculations. Automatic system balance is another feature of this package. Exhaust Ventilation Design Software algorithm for design is based on two methods: Balance by design (Static pressure balance and design by Blast gate. The most important section of software is a spreadsheet that is designed based on American Conference of Governmental Industrial Hygienists calculation sheets. Exhaust Ventilation Design Software is developed so that engineers familiar with American Conference of Governmental Industrial Hygienists datasheet can easily employ it for ventilation systems design. Other sections include Collector design section (settling chamber, cyclone, and packed tower, fan geometry and dimension data section, a unit converter section (that helps engineers to deal with units, a hood design section and a Persian HTML help. Psychometric correction is also considered in Exhaust Ventilation Design Software. In Exhaust Ventilation Design Software design process, efforts are focused on improving GUI (graphical user interface and use of programming standards in software design. Reliability of software has been evaluated and results show acceptable accuracy.

Noninvasive Ventilation in Premature Neonates.

Science.gov (United States)

Flanagan, Keri Ann

2016-04-01

The use of noninvasive ventilation is a constantly evolving treatment option for respiratory disease in the premature infant. The goals of these noninvasive ventilation techniques are to improve gas exchange in the premature infant's lungs and to minimize the need for intubation and invasive mechanical ventilation. The goals of this article are to consider various uses of nasal interfaces, discuss skin care and developmental positioning concerns faced by the bedside nurse, and discuss the medical management aimed to reduce morbidity and mortality. This article explores the nursing role, the advances in medical strategies for noninvasive ventilation, and the team approach to noninvasive ventilation use in this population. Search strategy included a literature review on medical databases, such as EBSCOhost, CINAHL, PubMed, and NeoReviews. Innovative products, nursing research on developmental positioning and skin care, and advanced medical management have led to better and safer outcomes for premature infants requiring noninvasive ventilation. The medical focus of avoiding long-term mechanical ventilation would not be possible without the technology to provide noninvasive ventilation to these premature infants and the watchful eye of the nurse in terms of careful positioning, preventing skin breakdown and facial scarring, and a proper seal to maximize ventilation accuracy. This article encourages nursing-based research to quantify some of the knowledge about skin care and positioning as well as research into most appropriate uses for noninvasive ventilation devices.

Ventilation systems

International Nuclear Information System (INIS)

Gossler

1980-01-01

The present paper deals with - controlled area ventilation systems - ventilation systems for switchgear-building and control-room - other ventilation systems for safety equipments - service systems for ventilation systems. (orig./RW)

Ventilation of nuclear rooms and operators' protection

International Nuclear Information System (INIS)

Vavasseur, C.

1985-01-01

Ventilation systems are designed to guarantee air replacement in rooms so as to evacuate gases, odors and aerosols liable to be produced therein. This air is conditioned, filtered, heated, and the relative humidity checked. At the outlet, a filtration system adapted to the type of effluent prevents the external dispersion of toxic substances. Ventilation is defined by the air change time. A comfort rule recommends reducing the velocities reaching the person present in less than 0.2 m/sec. This reduction is achieved by adjusting the natural property of the jets, induction, by means of diffusers placed at the vents

Tidal ventilation distribution during pressure-controlled ventilation and pressure support ventilation in post-cardiac surgery patients.

Science.gov (United States)

Blankman, P; VAN DER Kreeft, S M; Gommers, D

2014-09-01

Inhomogeneous ventilation is an important contributor to ventilator-induced lung injury. Therefore, this study examines homogeneity of lung ventilation by means of electrical impedance tomography (EIT) measurements during pressure-controlled ventilation (PCV) and pressure support ventilation (PSV) using the same ventilation pressures. Twenty mechanically ventilated patients were studied after cardiac surgery. On arrival at the intensive care unit, ventilation distribution was measured with EIT just above the diaphragm for 15 min. After awakening, PCV was switched to PSV and EIT measurements were again recorded. Tidal impedance variation, a measure of tidal volume, increased during PSV compared with PCV, despite using the same ventilation pressures (P = 0.045). The distribution of tidal ventilation to the dependent lung region was more pronounced during PSV compared with PCV, especially during the first half of the inspiration. An even distribution of tidal ventilation between the dependent and non-dependent lung regions was seen during PCV at lower tidal volumes (tidal volumes (≥ 8 ml/kg). In addition, the distribution of tidal ventilation was predominantly distributed to the dependent lung during PSV at low tidal volumes. In post-cardiac surgery patients, PSV showed improved ventilation of the dependent lung region due to the contribution of the diaphragm activity, which is even more pronounced during lower assist levels. © 2014 The Acta Anaesthesiologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

Ventilation of uranium mines

International Nuclear Information System (INIS)

Francois, Y.; Pradel, J.; Zettwoog, P.; Dumas, M.

1975-01-01

In the first part of the paper the authors describe the ventilation of French mines in terms of the primary ventilation system, which brings the outside air close to the working places using the overall structure of the mine to form the airways, and the secondary ventilation system, which is for the distribution of the primary air or for the ventilation of the development drifts and blind tunnels. Brief mention is made of the French regulations on the ventilation of mines in general and uranium mines in particular. The authors describe the equipment used and discuss the installed capacities and air flow per man and per working place. The difficulties encountered in properly ventilating various types of working places are mentioned, such as sublevel development drifts, reinforced stopes, and storage chambers with an artificial crown. The second part of the paper is devoted to computer calculations of the primary ventilation system. It is explained why the Commissariat a l'energie atomique has found it necessary to make these calculations. Without restating the mathematical theories underlying the methods employed, the authors demonstrate how simple measuring instruments and a small-size computer can be used to solve the ventilation problems arising in French mines. Emphasis is given to the layout of the ventilation system and to air flow and negative pressure measurements at the base of the mine. The authors show how calculations can be applied to new heading operations, a change in resistance, the replacement or addition of a ventilator, and a new air inlet or outlet. The authors come to the conclusion that since ventilation is at present the most reliable way of avoiding the pollution of mines, a thorough knowledge of the capabilities in this respect can often help improve working conditions. Despite the progress made, however, constant surveillance of the ventilation systems in uranium mines by a separate team with no responsibility for production problems is

Ventilation of uranium mines

International Nuclear Information System (INIS)

Francois, Y.; Pradel, J.; Zettwoog, P.; Dumas, M.

1975-01-01

In the first part of the paper the authors describe the ventilation of French mines in terms of the primary ventilation system, which brings the outside air close to the working places using the overall structure of the mine to form the airways, and the secondary ventilation system, which is for the distribution of the primary air or for the ventilation of the development drifts and blind tunnels. Brief mention is made of the French regulations on the ventilation of mines in general and uranium mines in particular. The authors describe the equipment used and discuss the installed capacities and air flow per man and per working place. The difficulties encountered in properly ventilating various types of working places are mentioned, such as sub-level development drifts, reinforced stopes, and storage chambers with an artificial crown. The second part of the paper is devoted to computer calculations of the primary ventilation system. It is explained why the Commissariat a l'energie atomique has found it necessary to make these calculations. Without restating the mathematical theories underlying the methods employed, the authors demonstrate how simple measuring instruments and a small-size computer can be used to solve the ventilation problems arising in French mines. Emphasis is given to the layout of the ventilation system and to air flow and negative pressure measurements at the base of the mine. The authors show how calculations can be applied to new heading operations, a change in resistance, the replacement or addition of a ventilator, and a new air inlet or outlet. The authors come to the conclusion that since ventilation is at present the most reliable way of avoiding the pollution of mines, a thorough knowledge of the capabilities in this respect can often help improve working conditions. Despite the progress made, however, constant surveillance of the ventilation systems in uranium mines by a separate team with no responsibility for production problems is

Underground ventilation remote monitoring and control system

International Nuclear Information System (INIS)

Strever, M.T.; Wallace, K.G. Jr.; McDaniel, K.H.

1995-01-01

This paper presents the design and installation of an underground ventilation remote monitoring and control system at the Waste Isolation Pilot Plant. This facility is designed to demonstrate safe underground disposal of U.S. defense generated transuranic nuclear waste. To improve the operability of the ventilation system, an underground remote monitoring and control system was designed and installed. The system consists of 15 air velocity sensors and 8 differential pressure sensors strategically located throughout the underground facility providing real-time data regarding the status of the ventilation system. In addition, a control system was installed on the main underground air regulators. The regulator control system gives indication of the regulator position and can be controlled either locally or remotely. The sensor output is displayed locally and at a central surface location through the site-wide Central Monitoring System (CMS). The CMS operator can review all sensor data and can remotely operate the main underground regulators. Furthermore, the Virtual Address Extension (VAX) network allows the ventilation engineer to retrieve real-time ventilation data on his personal computer located in his workstation. This paper describes the types of sensors selected, the installation of the instrumentation, and the initial operation of the remote monitoring system

Realtime mine ventilation simulation

International Nuclear Information System (INIS)

McDaniel, K.H.

1997-01-01

This paper describes the development of a Windows based, interactive mine ventilation simulation software program at the Waste Isolation Pilot Plant (WIPP). To enhance the operation of the underground ventilation system, Westinghouse Electric Corporation developed the program called WIPPVENT. While WIPPVENT includes most of the functions of the commercially available simulation program VNETPC and uses the same subroutine to calculate airflow distributions, the user interface has been completely rewritten as a Windows application with screen graphics. WIPPVENT is designed to interact with WIPP ventilation monitoring systems through the sitewise Central monitoring System. Data can be continuously collected from the Underground Ventilation Remote Monitoring and Control System (e.g., air quantity and differential pressure) and the Mine Weather Stations (psychrometric data). Furthermore, WIPPVENT incorporates regulator characteristic curves specific to the site. The program utilizes this data to create and continuously update a REAL-TIME ventilation model. This paper discusses the design, key features, and interactive capabilities of WIPPVENT

What does the scientific literature tell us about the ventilation-health relationship in public and residential buildings?

DEFF Research Database (Denmark)

Carrer, Paolo; Wargocki, Pawel; Fanetti, Annaclara

2015-01-01

. Effects on health were seen for a wide range of outdoor ventilation rates from 6 to 7 L/s per person, which were the lowest ventilation rates at which no effects on any health outcomes were observed in field studies, up to 25–40 L/s per person, which were in some studies the lowest outdoor ventilation...... rates at which no effects on health outcomes were seen. These data show that, in general, higher ventilation rates in many cases will reduce health outcomes, and that there are the minimum rates, at which some health outcomes can be avoided. But these data have many limitations, such as crude estimation...... of outdoor ventilation rates, diversity and variability of ventilation rates at which effects were seen, a diversity of outcomes (in case of health otcomes being mainly acute not chronic). Among other limitations there are incomplete data on the strength of pollution sources and exposures as well as a wide...

Mechanical Ventilation

Science.gov (United States)

... ventilation is a life support treatment. A mechanical ventilator is a machine that helps people breathe when ... to breathe enough on their own. The mechanical ventilator is also called a ventilator , respirator, or breathing ...

Intraoperative protective mechanical ventilation and risk of postoperative respiratory complications: hospital based registry study.

Science.gov (United States)

Ladha, Karim; Vidal Melo, Marcos F; McLean, Duncan J; Wanderer, Jonathan P; Grabitz, Stephanie D; Kurth, Tobias; Eikermann, Matthias

2015-07-14

To evaluate the effects of intraoperative protective ventilation on major postoperative respiratory complications and to define safe intraoperative mechanical ventilator settings that do not translate into an increased risk of postoperative respiratory complications. Hospital based registry study. Academic tertiary care hospital and two affiliated community hospitals in Massachusetts, United States. 69,265 consecutively enrolled patients over the age of 18 who underwent a non-cardiac surgical procedure between January 2007 and August 2014 and required general anesthesia with endotracheal intubation. Protective ventilation, defined as a median positive end expiratory pressure (PEEP) of 5 cmH2O or more, a median tidal volume of less than 10 mL/kg of predicted body weight, and a median plateau pressure of less than 30 cmH2O. Composite outcome of major respiratory complications, including pulmonary edema, respiratory failure, pneumonia, and re-intubation. Of the 69,265 enrolled patients 34,800 (50.2%) received protective ventilation and 34,465 (49.8%) received non-protective ventilation intraoperatively. Protective ventilation was associated with a decreased risk of postoperative respiratory complications in multivariable regression (adjusted odds ratio 0.90, 95% confidence interval 0.82 to 0.98, P=0.013). The results were similar in the propensity score matched cohort (odds ratio 0.89, 95% confidence interval 0.83 to 0.97, P=0.004). A PEEP of 5 cmH2O and median plateau pressures of 16 cmH2O or less were associated with the lowest risk of postoperative respiratory complications. Intraoperative protective ventilation was associated with a decreased risk of postoperative respiratory complications. A PEEP of 5 cmH2O and a plateau pressure of 16 cmH2O or less were identified as protective mechanical ventilator settings. These findings suggest that protective thresholds differ for intraoperative ventilation in patients with normal lungs compared with those used for patients

Characteristics of rain penetration through a gravity ventilator used for natural ventilation.

Science.gov (United States)

Kim, Taehyeung; Lee, Dong Ho; Ahn, Kwangseog; Ha, Hyunchul; Park, Heechang; Piao, Cheng Xu; Li, Xiaoyu; Seo, Jeoungyoon

2008-01-01

Gravity ventilators rely simply on air buoyancy to extract air and are widely used to exhaust air contaminants and heat from workplaces using minimal energy. They are designed to maximize the exhaust flow rate, but the rain penetration sometimes causes malfunctioning. In this study, the characteristics of rain penetration through a ventilator were examined as a preliminary study to develop a ventilator with the maximum exhaust capacity while minimizing rain penetration. A model ventilator was built and exposed to artificial rain and wind. The paths, intensities and amounts of penetration through the ventilator were observed and measured in qualitative and quantitative fashions. In the first phase, the pathways and intensities of rain penetration were visually observed. In the second phase, the amounts of rain penetration were quantitatively measured under the different configurations of ventilator components that were installed based on the information obtained in the first-phase experiment. The effects of wind speed, grill direction, rain drainage width, outer wall height, neck height and leaning angle of the outer wall from the vertical position were analyzed. Wind speed significantly affected rain penetration. Under the low crosswind conditions, the rain penetration intensities were under the limit of detection. Under the high crosswind conditions, grill direction and neck height were the most significant factors in reducing rain penetration. The installation of rain drainage was also important in reducing rain penetration. The experimental results suggest that, with proper configurations of its components, a gravity ventilator can be used for natural ventilation without significant rain penetration problems.

Predicting the Air Quality, Thermal Comfort and Draught Risk for a Virtual Classroom with Desk-Type Personalized Ventilation Systems

Directory of Open Access Journals (Sweden)

Eusébio Z. E. Conceição

2018-02-01

Full Text Available This paper concerns the prediction of indoor air quality (IAQ, thermal comfort (TC and draught risk (DR for a virtual classroom with desk-type personalized ventilation system (PVS. This numerical study considers a coupling of the computational fluid dynamics (CFD, human thermal comfort (HTC and building thermal behavior (BTB numerical models. The following indexes are used: the predicted percentage of dissatisfied people (PPD index is used for the evaluation of the TC level; the carbon dioxide (CO2 concentration in the breathing zone is used for the calculation of IAQ; and the DR level around the occupants is used for the evaluation of the discomfort due to draught. The air distribution index (ADI, based in the TC level, the IAQ level, the effectiveness for heat removal and the effectiveness for contaminant removal, is used for evaluating the performance of the personalized air distribution system. The numerical simulation is made for a virtual classroom with six desks. Each desk is equipped with one PVS with two air terminal devices located overhead and two air terminal devices located below the desktop. In one numerical simulation six occupants are used, while in another simulation twelve occupants are considered. For each numerical simulation an air supply temperature of 20 °C and 24 °C is applied. The results obtained show that the ADI value is higher for twelve persons than for six persons in the classroom and it is higher for an inlet air temperature of 20 °C than for an inlet air temperature of 24 °C. In future works, more combinations of upper and lower air terminal devices located around the body area and more combinations of occupants located in the desks will be analyzed.

Evaluation of Fractional Regional Ventilation Using 4D-CT and Effects of Breathing Maneuvers on Ventilation

International Nuclear Information System (INIS)

Mistry, Nilesh N.; Diwanji, Tejan; Shi, Xiutao; Pokharel, Sabin; Feigenberg, Steven; Scharf, Steven M.; D'Souza, Warren D.

2013-01-01

Purpose: Current implementations of methods based on Hounsfield units to evaluate regional lung ventilation do not directly incorporate tissue-based mass changes that occur over the respiratory cycle. To overcome this, we developed a 4-dimensional computed tomography (4D-CT)-based technique to evaluate fractional regional ventilation (FRV) that uses an individualized ratio of tidal volume to end-expiratory lung volume for each voxel. We further evaluated the effect of different breathing maneuvers on regional ventilation. The results from this work will help elucidate the relationship between global and regional lung function. Methods and Materials: Eight patients underwent 3 sets of 4D-CT scans during 1 session using free-breathing, audiovisual guidance, and active breathing control. FRV was estimated using a density-based algorithm with mass correction. Internal validation between global and regional ventilation was performed by use of the imaging data collected during the use of active breathing control. The impact of breathing maneuvers on FRV was evaluated comparing the tidal volume from 3 breathing methods. Results: Internal validation through comparison between the global and regional changes in ventilation revealed a strong linear correlation (slope of 1.01, R 2 of 0.97) between the measured global lung volume and the regional lung volume calculated by use of the “mass corrected” FRV. A linear relationship was established between the tidal volume measured with the automated breathing control system and FRV based on 4D-CT imaging. Consistently larger breathing volumes were observed when coached breathing techniques were used. Conclusions: The technique presented improves density-based evaluation of lung ventilation and establishes a link between global and regional lung ventilation volumes. Furthermore, the results obtained are comparable with those of other techniques of functional evaluation such as spirometry and hyperpolarized-gas magnetic resonance

Evaluation of Fractional Regional Ventilation Using 4D-CT and Effects of Breathing Maneuvers on Ventilation

Energy Technology Data Exchange (ETDEWEB)

Mistry, Nilesh N., E-mail: nmistry@som.umaryland.edu [Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland (United States); Diwanji, Tejan; Shi, Xiutao [Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland (United States); Pokharel, Sabin [Morgan State University, Baltimore, Maryland (United States); Feigenberg, Steven [Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland (United States); Scharf, Steven M. [Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland (United States); D' Souza, Warren D. [Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland (United States)

2013-11-15

Purpose: Current implementations of methods based on Hounsfield units to evaluate regional lung ventilation do not directly incorporate tissue-based mass changes that occur over the respiratory cycle. To overcome this, we developed a 4-dimensional computed tomography (4D-CT)-based technique to evaluate fractional regional ventilation (FRV) that uses an individualized ratio of tidal volume to end-expiratory lung volume for each voxel. We further evaluated the effect of different breathing maneuvers on regional ventilation. The results from this work will help elucidate the relationship between global and regional lung function. Methods and Materials: Eight patients underwent 3 sets of 4D-CT scans during 1 session using free-breathing, audiovisual guidance, and active breathing control. FRV was estimated using a density-based algorithm with mass correction. Internal validation between global and regional ventilation was performed by use of the imaging data collected during the use of active breathing control. The impact of breathing maneuvers on FRV was evaluated comparing the tidal volume from 3 breathing methods. Results: Internal validation through comparison between the global and regional changes in ventilation revealed a strong linear correlation (slope of 1.01, R{sup 2} of 0.97) between the measured global lung volume and the regional lung volume calculated by use of the “mass corrected” FRV. A linear relationship was established between the tidal volume measured with the automated breathing control system and FRV based on 4D-CT imaging. Consistently larger breathing volumes were observed when coached breathing techniques were used. Conclusions: The technique presented improves density-based evaluation of lung ventilation and establishes a link between global and regional lung ventilation volumes. Furthermore, the results obtained are comparable with those of other techniques of functional evaluation such as spirometry and hyperpolarized-gas magnetic

Methodology for ventilation/perfusion SPECT

DEFF Research Database (Denmark)

Bajc, Marika; Neilly, Brian; Miniati, Massimo

2010-01-01

radiolabeled liquid aerosols are not restricted to the presence of obstructive lung disease. Radiolabeled macroaggregated human albumin is the imaging agent of choice for perfusion scintigraphy. An optimal combination of nuclide activities and acquisition times for ventilation and perfusion, collimators......Ventilation/perfusion single-photon emission computed tomography (V/Q SPECT) is the scintigraphic technique of choice for the diagnosis of pulmonary embolism and many other disorders that affect lung function. Data from recent ventilation studies show that the theoretic advantages of Technegas over......, and imaging matrix yields an adequate V/Q SPECT study in approximately 20 minutes of imaging time. The recommended protocol based on the patient remaining in an unchanged position during the initial ventilation study and the perfusion study allows presentation of matching ventilation and perfusion slices...

Comparison of two modes of ventilation after fast-track cardiac surgery: Adaptive support ventilation versus synchronized intermittent mandatory ventilation

International Nuclear Information System (INIS)

Aghadavoudi, O.

2012-01-01

Objective: There is substantial debate regarding the appropriate protocol for ventilatory management in fast-track cardiac anesthesia (FTCA). This study was carried out to assess and compare the risks and benefits of respiratory weaning based on adaptive support ventilation (ASV) and synchronized intermittent mandatory ventilation (SIMV) after uncomplicated cardiac surgery. Methodology: In a randomized clinical trial, after receiving approval of the Department Research Committee and informed consent from study subjects, 100 patients undergoing elective coronary artery bypass graft (CABG) surgery with cardiopulmonary bypass (CPB) were enrolled during a 4-month period at a university-based hospital. After surgery and admission to the intensive care unit (ICU), patients were randomized to ASV and SIMV groups. Arterial blood gas (ABG) and hemodynamic variables, respiratory and ventilator characteristics including lung compliance, rapid shallow breathing index (RSBI), tidal volume (TV), respiratory rate (RR), peak inspiratory pressure (P peak), mean airway pressure (p mean), Pao2/FIo2, duration of mechanical ventilation and tracheal intubation, and length of ICU stay were recorded and compared between the two groups. The data were analyzed in 82 patients after considering the exclusion criteria. Results: There were no differences between ASV and SIMV groups in demographics and preoperative characteristics. The duration of tracheal intubation and the length of ICU stay were similar in both groups. There were no statistically and clinically relevant differences between the two groups in ABG, hemodynamic changes, and respiratory and ventilator characteristics during ICU stay. Conclusion: Although ASV may facilitate postoperative respiratory management in FTCA, both ASV and SIMV provide similarly safe and practicable respiratory weaning in the cardiac ICU. The evaluation of potential advantages in patient outcomes and resource utilization of respiratory weaning based on ASV

Displacement ventilation

DEFF Research Database (Denmark)

Kosonen, Risto; Melikov, Arsen Krikor; Mundt, Elisabeth

The aim of this Guidebook is to give the state-of-the art knowledge of the displacement ventilation technology, and to simplify and improve the practical design procedure. The Guidebook discusses methods of total volume ventilation by mixing ventilation and displacement ventilation and it gives...... insights of the performance of the displacement ventilation. It also shows practical case studies in some typical applications and the latest research findings to create good local micro-climatic conditions....

Battery life of portable home ventilators: effects of ventilator settings.

Science.gov (United States)

Falaize, Line; Leroux, Karl; Prigent, Hélène; Louis, Bruno; Khirani, Sonia; Orlikowski, David; Fauroux, Brigitte; Lofaso, Frédéric

2014-07-01

The battery life (BL) of portable home ventilator batteries is reported by manufacturers. The aim of this study was to evaluate the effects of ventilator mode, breathing frequency, PEEP, and leaks on the BL of 5 commercially available portable ventilators. The effects of the ventilator mode (volume controlled-continuous mandatory ventilation [VC-CMV] vs pressure support ventilation [PSV]), PEEP 5 cm H2O, breathing frequency (10, 15, and 20 breaths/min), and leaks during both volume-targeted ventilation and PSV on the BL of 5 ventilators (Elisée 150, Monnal T50, PB560, Vivo 50, and Trilogy 100) were evaluated. Each ventilator was ventilated with a test lung at a tidal volume of 700 ml and an inspiratory time of 1.2 s in the absence of leaks. Switching from PSV to VC-CMV or the addition of PEEP did not significantly change ventilator BL. The increase in breathing frequency from 10 to 20 breaths/min decreased the BL by 18 ± 11% (P = .005). Leaks were associated with an increase in BL during the VC-CMV mode (18 ± 20%, P = .04) but a decrease in BL during the PSV mode (-13 ± 15%, P = .04). The BL of home ventilators depends on the ventilator settings. BL is not affected by the ventilator mode (VC-CMV or PSV) or the addition of PEEP. BL decreases with an increase in breathing frequency and during leaks with a PSV mode, whereas leaks increase the duration of ventilator BL during VC-CMV. Copyright © 2014 by Daedalus Enterprises.

VENTILATION MODEL

International Nuclear Information System (INIS)

V. Chipman

2002-01-01

The purpose of the Ventilation Model is to simulate the heat transfer processes in and around waste emplacement drifts during periods of forced ventilation. The model evaluates the effects of emplacement drift ventilation on the thermal conditions in the emplacement drifts and surrounding rock mass, and calculates the heat removal by ventilation as a measure of the viability of ventilation to delay the onset of peak repository temperature and reduce its magnitude. The heat removal by ventilation is temporally and spatially dependent, and is expressed as the fraction of heat carried away by the ventilation air compared to the fraction of heat produced by radionuclide decay. One minus the heat removal is called the wall heat fraction, or the remaining amount of heat that is transferred via conduction to the surrounding rock mass. Downstream models, such as the ''Multiscale Thermohydrologic Model'' (BSC 2001), use the wall heat fractions as outputted from the Ventilation Model to initialize their postclosure analyses

Patient-Ventilator Dyssynchrony

Directory of Open Access Journals (Sweden)

Elvira-Markela Antonogiannaki

2017-11-01

Full Text Available In mechanically ventilated patients, assisted mechanical ventilation (MV is employed early, following the acute phase of critical illness, in order to eliminate the detrimental effects of controlled MV, most notably the development of ventilator-induced diaphragmatic dysfunction. Nevertheless, the benefits of assisted MV are often counteracted by the development of patient-ventilator dyssynchrony. Patient-ventilator dyssynchrony occurs when either the initiation and/or termination of mechanical breath is not in time agreement with the initiation and termination of neural inspiration, respectively, or if the magnitude of mechanical assist does not respond to the patient’s respiratory demand. As patient-ventilator dyssynchrony has been associated with several adverse effects and can adversely influence patient outcome, every effort should be made to recognize and correct this occurrence at bedside. To detect patient-ventilator dyssynchronies, the physician should assess patient comfort and carefully inspect the pressure- and flow-time waveforms, available on the ventilator screen of all modern ventilators. Modern ventilators offer several modifiable settings to improve patient-ventilator interaction. New proportional modes of ventilation are also very helpful in improving patient-ventilator interaction.

Experiences of exclusion when living on a ventilator: reflections based on the application of Julia Kristeva's philosophy to caring science.

Science.gov (United States)

Lindahl, Berit

2011-01-01

The research presented in this work represents reflections in the light of Julia Kristeva's philosophy concerning empirical data drawn from research describing the everyday life of people dependent on ventilators. It also presents a qualitative and narrative methodological approach from a person-centred perspective. Most research on home ventilator treatment is biomedical. There are a few published studies describing the situation of people living at home on a ventilator but no previous publications have used the thoughts in Kristeva's philosophy applied to this topic from a caring science perspective. The paper also addresses what a life at home on a ventilator may be like and will hopefully add some new aspects to the discussion of philosophical issues in nursing and the very essence of care. Kristeva's philosophy embraces phenomena such as language, abjection, body, and love, allowing her writings to make a fruitful contribution to nursing philosophy in that they strengthen, expand, and deepen a caring perspective. Moreover, her writings about revolt having the power to create hope add an interesting aspect to the work of earlier philosophers and nursing theorists. © 2010 Blackwell Publishing Ltd.

Initial mechanical ventilator settings and lung protective ventilation in the ED.

Science.gov (United States)

Wilcox, Susan R; Richards, Jeremy B; Fisher, Daniel F; Sankoff, Jeffrey; Seigel, Todd A

2016-08-01

Mechanical ventilation with low tidal volumes has been shown to improve outcomes for patients both with and without acute respiratory distress syndrome. This study aims to characterize mechanically ventilated patients in the emergency department (ED), describe the initial ED ventilator settings, and assess for associations between lung protective ventilation strategies in the ED and outcomes. This was a multicenter, prospective, observational study of mechanical ventilation at 3 academic EDs. We defined lung protective ventilation as a tidal volume of less than or equal to 8 mL/kg of predicted body weight and compared outcomes for patients ventilated with lung protective vs non-lung protective ventilation, including inhospital mortality, ventilator days, intensive care unit length of stay, and hospital length of stay. Data from 433 patients were analyzed. Altered mental status without respiratory pathology was the most common reason for intubation, followed by trauma and respiratory failure. Two hundred sixty-one patients (60.3%) received lung protective ventilation, but most patients were ventilated with a low positive end-expiratory pressure, high fraction of inspired oxygen strategy. Patients were ventilated in the ED for a mean of 5 hours and 7 minutes but had few ventilator adjustments. Outcomes were not significantly different between patients receiving lung protective vs non-lung protective ventilation. Nearly 40% of ED patients were ventilated with non-lung protective ventilation as well as with low positive end-expiratory pressure and high fraction of inspired oxygen. Despite a mean ED ventilation time of more than 5 hours, few patients had adjustments made to their ventilators. Copyright © 2016 Elsevier Inc. All rights reserved.

Performance of Ductless Personalized Ventilation in Open-Plan Office - Field Survey

DEFF Research Database (Denmark)

Dalewski, Mariusz; Ezzat Khalifa, H.; Melikov, Arsen Krikor

2013-01-01

A field survey was conducted in an architectural company located in Syracuse, USA. 54 employees who participated in the survey performed mostly design work. Large open-plan office and several single offices ventilated by displacement air distribution were included in the survey. Ductless...

Ceiling-mounted personalized ventilation system integrated with a secondary air distribution system - a human response study in hot and humid climate

DEFF Research Database (Denmark)

Bin, Yang; Sekhar, S.C.; Melikov, Arsen Krikor

2010-01-01

The benefits of thermal comfort and indoor air quality with personalized ventilation (PV) systems have been demonstrated in recent studies. One of the barriers for wide spread acceptance by architects and HVAC designers has been attributed to challenges and constraints faced in the integration...... performed with tropically acclimatized subjects in a Field Environmental Chamber. Thirty-two subjects performed normal office work and could choose to be exposed to four different PV airflow rates (4, 8, 12, and 16 L/s), thus offering themselves a reasonable degree of individual control. Ambient...

Wearable Personal Exhaust Ventilation, WPEV: Improved Indoor Air Quality and Reduced Exposure to Air Exhaled from a Sick Doctor

DEFF Research Database (Denmark)

Bolashikov, Zhecho D.; Barova, Maria; Melikov, Arsen K.

2015-01-01

pause) and a tidal flow rate of 6 L/min. A second thermal manikin and heated dummy were used to resemble lying patients. Exhaled air by the doctor was mixed with tracer gas to mimic pathogens. The wearable personal exhaust unit was positioned frontally by the mouth of the doctor at three distances: 0.......02, 0.04, and 0.06 m. It was operated at 0.25 or 0.50 L/s under mixing background ventilation at three air changes per hour. The effect of the wearable exhaust unit geometry by modifying the exhaust surface, as well as the posture of the doctor, standing or seated, was also studied. The use...... of the wearable personal exhaust resulted in cleaner air in the room compared to mixing alone at 12 air changes per hour, reducing the exposure of the two patients. The nozzle geometry and posture of the doctor affected the indoor exposure to exhaled air. The high potential to capture exhaled air makes the device...

Effect of a ventilator-focused intervention on the rate of Acinetobacter baumannii infection among ventilated patients.

Science.gov (United States)

Cohen, Regev; Shimoni, Zvi; Ghara, Riad; Ram, Ron; Ben-Ami, Ronen

2014-09-01

Acinetobacter baumannii is a leading cause of ventilator-associated pneumonia, often as a result of ventilator equipment contamination. Evidence-based guidance on optimal care of ventilator equipment to prevent infection is lacking. Here, we report on a significant and persistent reduction in A baumannii infection rates achieved by introducing a strict policy on ventilator care. We implemented an institution-wide ventilator care policy that included routine exchange of breathing circuits and external bacterial filters (every 7-14 days) and replacement followed by routine sterilization of internal bacterial filters (every 4-8 weeks). We analyzed sputum cultures and patient outcomes among ventilated patients before and after the intervention. Between January 2012 and March 2013, 321 patients ventilated for more than 3 days comprised the study cohort. Health care-associated A baumannii acquisition was significantly reduced during the postintervention period (33% vs 16%; odds ratio, 0.39; 95% confidence interval, 0.23-0.67; P = .0008). Additionally, the median time to A baumannii acquisition was significantly longer postintervention (59 vs 21 days; P < .0001). A baumannii ventilator-associated pneumonia risk was also reduced postintervention (odds ratio, 0.39; P = .005). Implementing a stricter standard of ventilator care than that currently defined in published guidelines can significantly decrease health care-associated A baumannii acquisition and related adverse outcomes among ventilated patients. Copyright © 2014 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Mosby, Inc. All rights reserved.

Low-energy mechanical ventilation

DEFF Research Database (Denmark)

Andersen, Claus Wessel; Hviid, Christian Anker

2014-01-01

and with as little energy consumption as 41.1 kWh/m2/year including heating and all building services with no use of renewable energy such as PVcells or solar heating. One of the key means of reaching the objectives was to implement mechanical ventilation with low pressure loss and therefore low energy consumption....... The project consists of two buildings, building one is 6 stories high, and building two is 4 stories high. The buildings have a gross area of 50,500 m2 including underground parking. The ventilation and indoor climate concept was to use mechanical ventilation together with mechanical cooling and fanassisted......, with an average of 1.1 kJ/m3. The yearly mean SFP based on estimated runtime is approx. 0.8 kJ/m3. The case shows the unlocked potential that lies within mechanical ventilation for nearzero energy consuming buildings....

Ventilator use, respiratory problems, and caregiver well-being in korean patients with amyotrophic lateral sclerosis receiving home-based care.

Science.gov (United States)

Kim, Chul-Hoon; Kim, Myoung Soo

2014-10-01

The purpose of this study was to describe the status of ventilator use, respiratory problems, and caregiver well-being relating to patients with amyotrophic lateral sclerosis (ALS) using a home-based ventilator as well as to examine the relationship among ventilator use, respiratory problems, and caregiver well-being. Patients with ALS (n = 141) registered in the Severe-Rare Disease Center of the Korean Center for Disease Control and their caregivers (n = 83) were surveyed from August 2008 to April 2009. Trained research assistants visited patient homes; collected data using questionnaires; and then performed analyses with descriptive statistics, χ test, and t test as well as partial correlation analysis using SPSS WIN 18.0. Thirty-two patients used noninvasive ventilation (NIV), and 109 used tracheostomy and mechanical ventilation (TMV). One hundred of the TMV patients used the ventilator 24 hours per day. The ventilator circuit exchange cycle was 0.96 times per month for NIV patients and 1.17 times per month for TMV patients (t = -4.91, p NIV patients had a higher level of tidal volume than TMV patients (t = 3.34, p = .001). Approximately 22% of NIV patients and 24% of TMV patients used one or more physiotherapies for airway clearance. There was a significant relationship between hypoventilation symptoms and caregiver burden (r = .31, p = .006). Hypoventilation symptoms were positively related to physiotherapy (r = .24, p = .042), and physiotherapy was positively related to caregiver burden (r = .24, p = .043). On the basis of the findings of this study, care management for patients with ALS with a home-based ventilator as well as their caregiver's well-being was relatively inappropriate. We recommend that community-based support programs and burden relief programs be considered as managerial interventions.

Demand Controlled Ventilation in a Combined Ventilation and Radiator System

OpenAIRE

Hesaraki, Arefeh; Holmberg, Sture

2013-01-01

With growing concerns for efficient and sustainable energy treatment in buildings there is a need for balanced and intelligent ventilation solutions. This paper presents a strategy for demand controlled ventilation with ventilation radiators, a combined heating and ventilation system. The ventilation rate was decreased from normal requirements (per floor area) of 0.375 l·s-1·m-2 to 0.100 l·s-1·m-2 when the residence building was un-occupied. The energy saving potential due to decreased ventil...

[Lung protective ventilation. Ventilatory modes and ventilator parameters].

Science.gov (United States)

Schädler, Dirk; Weiler, Norbert

2008-06-01

Mechanical ventilation has a considerable potential for injuring the lung tissue. Therefore, attention has to be paid to the proper choice of ventilatory mode and settings to secure lung-protective ventilation whenever possible. Such ventilator strategy should account for low tidal volume ventilation (6 ml/kg PBW), limited plateau pressure (30 to 35 cm H2O) and positive end-expiratory pressure (PEEP). It is unclear whether pressure controlled or volume controlled ventilation with square flow profile is beneficial. The adjustment of inspiration and expiration time should consider the actual breathing mechanics and anticipate the generation of intrinsic PEEP. Ventilatory modes with the possibility of supporting spontaneous breathing should be used as soon as possible.

Variable mechanical ventilation.

Science.gov (United States)

Fontela, Paula Caitano; Prestes, Renata Bernardy; Forgiarini, Luiz Alberto; Friedman, Gilberto

2017-01-01

To review the literature on the use of variable mechanical ventilation and the main outcomes of this technique. Search, selection, and analysis of all original articles on variable ventilation, without restriction on the period of publication and language, available in the electronic databases LILACS, MEDLINE®, and PubMed, by searching the terms "variable ventilation" OR "noisy ventilation" OR "biologically variable ventilation". A total of 36 studies were selected. Of these, 24 were original studies, including 21 experimental studies and three clinical studies. Several experimental studies reported the beneficial effects of distinct variable ventilation strategies on lung function using different models of lung injury and healthy lungs. Variable ventilation seems to be a viable strategy for improving gas exchange and respiratory mechanics and preventing lung injury associated with mechanical ventilation. However, further clinical studies are necessary to assess the potential of variable ventilation strategies for the clinical improvement of patients undergoing mechanical ventilation.

Validating and improving CT ventilation imaging by correlating with ventilation 4D-PET/CT using 68Ga-labeled nanoparticles

International Nuclear Information System (INIS)

Kipritidis, John; Keall, Paul J.; Siva, Shankar; Hofman, Michael S.; Callahan, Jason; Hicks, Rodney J.

2014-01-01

Purpose: CT ventilation imaging is a novel functional lung imaging modality based on deformable image registration. The authors present the first validation study of CT ventilation using positron emission tomography with 68 Ga-labeled nanoparticles (PET-Galligas). The authors quantify this agreement for different CT ventilation metrics and PET reconstruction parameters. Methods: PET-Galligas ventilation scans were acquired for 12 lung cancer patients using a four-dimensional (4D) PET/CT scanner. CT ventilation images were then produced by applying B-spline deformable image registration between the respiratory correlated phases of the 4D-CT. The authors test four ventilation metrics, two existing and two modified. The two existing metrics model mechanical ventilation (alveolar air-flow) based on Hounsfield unit (HU) change (V HU ) or Jacobian determinant of deformation (V Jac ). The two modified metrics incorporate a voxel-wise tissue-density scaling (ρV HU and ρV Jac ) and were hypothesized to better model the physiological ventilation. In order to assess the impact of PET image quality, comparisons were performed using both standard and respiratory-gated PET images with the former exhibiting better signal. Different median filtering kernels (σ m = 0 or 3 mm) were also applied to all images. As in previous studies, similarity metrics included the Spearman correlation coefficient r within the segmented lung volumes, and Dice coefficient d 20 for the (0 − 20)th functional percentile volumes. Results: The best agreement between CT and PET ventilation was obtained comparing standard PET images to the density-scaled HU metric (ρV HU ) with σ m = 3 mm. This leads to correlation values in the ranges 0.22 ⩽ r ⩽ 0.76 and 0.38 ⩽ d 20 ⩽ 0.68, with r ¯ =0.42±0.16 and d ¯ 20 =0.52±0.09 averaged over the 12 patients. Compared to Jacobian-based metrics, HU-based metrics lead to statistically significant improvements in r ¯ and d ¯ 20 (p ¯ than for unscaled

Mine ventilation engineering

Energy Technology Data Exchange (ETDEWEB)

Hall, C.J.

1981-01-01

This book on mine ventilation covers psychometrics, airflow through roadways and ducts, natural ventilation, fans, instruments, ventilation surveys, auxiliary ventilation, air quality, and planning and economics.

The effect of electromagnetic interference from mobile communication on the performance of intensive care ventilators.

Science.gov (United States)

Jones, R P; Conway, D H

2005-08-01

Electromagnetic interference produced by wireless communication can affect medical devices and hospital policies exist to address this risk. During the transfer of ventilated patients, these policies may be compromised by essential communication between base and receiving hospitals. Local wireless networks (e.g. Bluetooth) may reduce the 'spaghetti syndrome' of wires and cables seen on intensive care units, but also generate electromagnetic interference. The aim of this study was to investigate these effects on displayed and actual ventilator performance. Five ventilators were tested: Drager Oxylog 2000, BREAS LTV-1000, Respironics BiPAP VISION, Puritan Bennett 7200 and 840. Electromagnetic interference was generated by three devices: Simoco 8020 radio handset, Nokia 7210 and Nokia 6230 mobile phone, Nokia 6230 communicating via Bluetooth with a Palm Tungsten T Personal Digital Assistant. We followed the American National Standard Recommended Practice for On-Site, Ad Hoc Testing (ANSI C63) for electromagnetic interference. We used a ventilator tester, to simulate healthy adult lungs and measure ventilator performance. The communication device under test was moved in towards each ventilator from a distance of 1 m in six axes. Alarms or error codes on the ventilator were recorded, as was ventilator performance. All ventilators tested, except for the Respironics VISION, showed a display error when subjected to electromagnetic interference from the Nokia phones and Simoco radio. Ventilator performance was only affected by the radio which caused the Puritan Bennett 840 to stop functioning completely. The transfer ventilators' performance were not affected by radio or mobile phone, although the mobile phone did trigger a low-power alarm. Effects on intensive care ventilators included display reset, with the ventilator restoring normal display function within 2 s, and low-power/low-pressure alarms. Bluetooth transmission had no effect on the function of all the

Developing evidence-based prescriptive ventilation rate standards for commercial buildings in California: a proposed framework

Energy Technology Data Exchange (ETDEWEB)

Mendell, Mark J.; Fisk, William J.

2014-02-01

Background - The goal of this project, with a focus on commercial buildings in California, was to develop a new framework for evidence-based minimum ventilation rate (MVR) standards that protect occupants in buildings while also considering energy use and cost. This was motivated by research findings suggesting that current prescriptive MVRs in commercial buildings do not provide occupants with fully safe and satisfactory indoor environments. Methods - The project began with a broad review in several areas ? the diverse strategies now used for standards or guidelines for MVRs or for environmental contaminant exposures, current knowledge about adverse human effects associated with VRs, and current knowledge about contaminants in commercial buildings, including their their presence, their adverse human effects, and their relationships with VRs. Based on a synthesis of the reviewed information, new principles and approaches are proposed for setting evidence-based VRs standards for commercial buildings, considering a range of human effects including health, performance, and acceptability of air. Results ? A review and evaluation is first presented of current approaches to setting prescriptive building ventilation standards and setting acceptable limits for human contaminant exposures in outdoor air and occupational settings. Recent research on approaches to setting acceptable levels of environmental exposures in evidence-based MVR standards is also described. From a synthesis and critique of these materials, a set of principles for setting MVRs is presented, along with an example approach based on these principles. The approach combines two sequential strategies. In a first step, an acceptable threshold is set for each adverse outcome that has a demonstrated relationship to VRs, as an increase from a (low) outcome level at a high reference ventilation rate (RVR, the VR needed to attain the best achievable levels of the adverse outcome); MVRs required to meet each

Design and performance of a rule-based controller in a naturally ventilated room

OpenAIRE

Marjanovic-Halburd, Ljiljana; Angelov, P.; Eftekhari, M. M.

2003-01-01

This paper reflects the final phase of the EPSRC project, and the PhD work of Marjanovic, on rule-based control in naturally ventilated buildings. Marjanovic is the second author. Eftekhari was her PhD supervisor.

Human versus Computer Controlled Selection of Ventilator Settings: An Evaluation of Adaptive Support Ventilation and Mid-Frequency Ventilation

Directory of Open Access Journals (Sweden)

Eduardo Mireles-Cabodevila

2012-01-01

Full Text Available Background. There are modes of mechanical ventilation that can select ventilator settings with computer controlled algorithms (targeting schemes. Two examples are adaptive support ventilation (ASV and mid-frequency ventilation (MFV. We studied how different clinician-chosen ventilator settings are from these computer algorithms under different scenarios. Methods. A survey of critical care clinicians provided reference ventilator settings for a 70 kg paralyzed patient in five clinical/physiological scenarios. The survey-derived values for minute ventilation and minute alveolar ventilation were used as goals for ASV and MFV, respectively. A lung simulator programmed with each scenario’s respiratory system characteristics was ventilated using the clinician, ASV, and MFV settings. Results. Tidal volumes ranged from 6.1 to 8.3 mL/kg for the clinician, 6.7 to 11.9 mL/kg for ASV, and 3.5 to 9.9 mL/kg for MFV. Inspiratory pressures were lower for ASV and MFV. Clinician-selected tidal volumes were similar to the ASV settings for all scenarios except for asthma, in which the tidal volumes were larger for ASV and MFV. MFV delivered the same alveolar minute ventilation with higher end expiratory and lower end inspiratory volumes. Conclusions. There are differences and similarities among initial ventilator settings selected by humans and computers for various clinical scenarios. The ventilation outcomes are the result of the lung physiological characteristics and their interaction with the targeting scheme.

Exposure to aerosol and gaseous pollutants in a room ventilated with mixing air distribution

DEFF Research Database (Denmark)

Bivolarova, Mariya Petrova; Ondráček, Jakub; Ždímal, Vladimír

2016-01-01

The present study investigates the aerosol and gas dispersal in a mechanically ventilated room and the personal exposure to these contaminants. The study was performed in a full-scale climate chamber. The room was air conditioned via mixing total volume ventilation system. The room occupancy was ...... of the thermal manikin were measured. The results showed higher exposure to the contaminants measured at the breathing zone than at the ambient air. The behaviour of the tracer gas and the aerosols was similar.......The present study investigates the aerosol and gas dispersal in a mechanically ventilated room and the personal exposure to these contaminants. The study was performed in a full-scale climate chamber. The room was air conditioned via mixing total volume ventilation system. The room occupancy...... was simulated by a sitting dressed thermal manikin with realistic body shape. During the experiments monodisperse aerosols of three sizes and nitrous oxide tracer gas were generated simultaneously from one location in the room. The aerosol and gas concentrations in the bulk room air and in the breathing zone...

Discussion for management of ventilation system in uranium mines

International Nuclear Information System (INIS)

Li Xianjie; Ren Jianjun; Hu Penghua

2014-01-01

Radon exhaustion and ventilation are surely regarded as key links for safety production and radiation protection in underground uranium mines, and the crucial point to achieve safety production goals lies in timely and accurately adjusting and controlling of ventilation technical measures and ventilation system management with the changing operation conditions of mines. This paper proposes corresponding countermeasures based on the respectively systematical analysis of daily ventilation management, ventilation facilities and structures management, and ventilation system information management in uranium mines. Furthermore, standardized management approaches and suggestions are put forward to realize standardization of uranium mines' ventilation management and radon exhaustion technique. (authors)

Ventilation models

Science.gov (United States)

Skaaret, Eimund

Calculation procedures, used in the design of ventilating systems, which are especially suited for displacement ventilation in addition to linking it to mixing ventilation, are addressed. The two zone flow model is considered and the steady state and transient solutions are addressed. Different methods of supplying air are discussed, and different types of air flow are considered: piston flow, plane flow and radial flow. An evaluation model for ventilation systems is presented.

Ventilator-associated pneumonia management in critical illness.

Science.gov (United States)

Albertos, Raquel; Caralt, Berta; Rello, Jordi

2011-03-01

Ventilator-associated pneumonia (VAP) is a frequent adverse event in the intensive care unit.We review recent publications about the management and prevention of VAP. The latest care bundles introduced standard interventions to facilitate implementation of evidence-based clinical guidelines and to improve the outcome of patients. Recent studies find that prevention management of ventilated patients decreases the risk of VAP. Enteral feeding, considered a risk factor for VAP, currently has been recommended, with appropriate administration, for all critical ill patients if no contraindications exist. In view of the recently available data, it can be concluded that the implementation of care bundles on the general management of ventilated patients in daily practice has reduced the VAP rates. The main pharmacological measures to prevent VAP are proper hands hygiene, high nurse-to-patient ratio, avoid unnecessary transfer of ventilated patients, use of noninvasive mechanical ventilation, shortening weaning period, avoid the use of nasal intubation, prevent bio-film deposition in endotracheal tube, aspiration of subglottic secretions, maintenance of adequate pressure of endotracheal cuffs, avoid manipulation of ventilator circuits, semi-recumbent position and adequate enteral feeding.In addition, updated guidelines incorporate more comprehensive diagnostic protocols to the evidence-based management of VAP.

Noninvasive ventilation.

Science.gov (United States)

Rabatin, J T; Gay, P C

1999-08-01

Noninvasive ventilation refers to the delivery of assisted ventilatory support without the use of an endotracheal tube. Noninvasive positive pressure ventilation (NPPV) can be delivered by using a volume-controlled ventilator, a pressure-controlled ventilator, a bilevel positive airway pressure ventilator, or a continuous positive airway pressure device. During the past decade, there has been a resurgence in the use of noninvasive ventilation, fueled by advances in technology and clinical trials evaluating its use. Several manufacturers produce portable devices that are simple to operate. This review describes the equipment, techniques, and complications associated with NPPV and also the indications for both short-term and long-term applications. NPPV clearly represents an important addition to the techniques available to manage patients with respiratory failure. Future clinical trials evaluating its many clinical applications will help to define populations of patients most apt to benefit from this type of treatment.

Computer program for sizing residential energy recovery ventilator

International Nuclear Information System (INIS)

Koontz, M.D.; Lee, S.M.; Spears, J.W.; Kesselring, J.P.

1991-01-01

Energy recovery ventilators offer the prospect of tighter control over residential ventilation rates than manual methods, such as opening windows, with a lesser energy penalty. However, the appropriate size of such a ventilator is not readily apparent in most situations. Sizing of energy recovery ventilation software was developed to calculate the size of ventilator necessary to satisfy ASHRAE Standard 62-1989, Ventilation for Acceptable Air Quality, or a user-specified air exchange rate. Inputs to the software include house location, structural characteristics, house operations and energy costs, ventilation characteristics, and HVAC system COP/efficiency. Based on these inputs, the program estimates the existing air exchange rate for the house, the ventilation rate required to meet the ASHRAE standard or user-specified air exchange rate, the size of the ventilator needed to meet the requirement, and the expected changes in indoor air quality and energy consumption. In this paper an illustrative application of the software is provided

Industrial ventilation

Science.gov (United States)

Goodfellow, H. D.

Industrial ventilation design methodology, using computers and using fluid dynamic models, is considered. It is noted that the design of a ventilation system must be incorporated into the plant design and layout at the earliest conceptual stage of the project. A checklist of activities concerning the methodology for the design of a ventilation system for a new facility is given. A flow diagram of the computer ventilation model shows a typical input, the initialization and iteration loop, and the output. The application of the fluid dynamic modeling techniques include external and internal flow fields, and individual sources of heat and contaminants. Major activities for a ventilation field test program are also addressed.

Diffuse Ceiling Ventilation

DEFF Research Database (Denmark)

Zhang, Chen; Yu, Tao; Heiselberg, Per Kvols

with conventional ventilation systems (mixing or displacement ventilation), diffuse ceiling ventilation can significantly reduce or even eliminate draught risk in the occupied zone. Moreover, this ventilation system presents a promising opportunity for energy saving, because of the low pressure loss, extended free...

Diffuse ceiling ventilation

DEFF Research Database (Denmark)

Zhang, Chen

Diffuse ceiling ventilation is an innovative ventilation concept where the suspended ceiling serves as air diffuser to supply fresh air into the room. Compared with conventional ventilation systems, diffuse ceiling ventilation can significantly reduce or even eliminate draught risk due to the low...

Radioaerosol ventilation imaging in ventilator-dependent patients. Technical considerations

International Nuclear Information System (INIS)

Vezina, W.; Chamberlain, M.; Vinitski, S.; King, M.; Nicholson, R.; Morgan, W.K.

1985-01-01

The differentiation of pulmonary embolism (PE) from regional ventilatory abnormalities accompanied by reduced perfusion requires contemporary perfusion and ventilation studies. Distinguishing these conditions in ventilator-dependent patients is aided by administering a Tc-99m aerosol to characterize regional ventilation, and by performing a conventional Tc-99m MAA perfusion study. The technique uses a simple in-house constructed apparatus. Simple photographic techniques suffice, but computer subtraction of perfusion from the combined perfusion-ventilation image renders interpretation easier if aerosol administration follows perfusion imaging. Multiple defects can be examined in a single study. Excluding normal or near-normal perfusion studies, PE was thought to be present in eight of 16 patients after perfusion imaging alone, but in only one of eight after added aerosol imaging. Angiography confirmed the diagnosis in that patient. Of the eight patients who had abnormal perfusion but were thought unlikely to have PE from the perfusion study alone, two had normal ventilation, and subsequently were shown to have PE by angiography. Because angiography was only performed on patients who were thought to have a high probability of PE on sequential perfusion-ventilation imaging, the true incidence of PE may have been higher. Aerosol ventilation imaging is a useful adjunct to perfusion imaging in patients on ventilators. It requires an efficient delivery system, particularly if aerosol administration follows perfusion imaging, as it does in this study

A knowledge- and model-based system for automated weaning from mechanical ventilation: technical description and first clinical application.

Science.gov (United States)

Schädler, Dirk; Mersmann, Stefan; Frerichs, Inéz; Elke, Gunnar; Semmel-Griebeler, Thomas; Noll, Oliver; Pulletz, Sven; Zick, Günther; David, Matthias; Heinrichs, Wolfgang; Scholz, Jens; Weiler, Norbert

2014-10-01

To describe the principles and the first clinical application of a novel prototype automated weaning system called Evita Weaning System (EWS). EWS allows an automated control of all ventilator settings in pressure controlled and pressure support mode with the aim of decreasing the respiratory load of mechanical ventilation. Respiratory load takes inspired fraction of oxygen, positive end-expiratory pressure, pressure amplitude and spontaneous breathing activity into account. Spontaneous breathing activity is assessed by the number of controlled breaths needed to maintain a predefined respiratory rate. EWS was implemented as a knowledge- and model-based system that autonomously and remotely controlled a mechanical ventilator (Evita 4, Dräger Medical, Lübeck, Germany). In a selected case study (n = 19 patients), ventilator settings chosen by the responsible physician were compared with the settings 10 min after the start of EWS and at the end of the study session. Neither unsafe ventilator settings nor failure of the system occurred. All patients were successfully transferred from controlled ventilation to assisted spontaneous breathing in a mean time of 37 ± 17 min (± SD). Early settings applied by the EWS did not significantly differ from the initial settings, except for the fraction of oxygen in inspired gas. During the later course, EWS significantly modified most of the ventilator settings and reduced the imposed respiratory load. A novel prototype automated weaning system was successfully developed. The first clinical application of EWS revealed that its operation was stable, safe ventilator settings were defined and the respiratory load of mechanical ventilation was decreased.

Ventilation Model

International Nuclear Information System (INIS)

Yang, H.

1999-01-01

The purpose of this analysis and model report (AMR) for the Ventilation Model is to analyze the effects of pre-closure continuous ventilation in the Engineered Barrier System (EBS) emplacement drifts and provide heat removal data to support EBS design. It will also provide input data (initial conditions, and time varying boundary conditions) for the EBS post-closure performance assessment and the EBS Water Distribution and Removal Process Model. The objective of the analysis is to develop, describe, and apply calculation methods and models that can be used to predict thermal conditions within emplacement drifts under forced ventilation during the pre-closure period. The scope of this analysis includes: (1) Provide a general description of effects and heat transfer process of emplacement drift ventilation. (2) Develop a modeling approach to simulate the impacts of pre-closure ventilation on the thermal conditions in emplacement drifts. (3) Identify and document inputs to be used for modeling emplacement ventilation. (4) Perform calculations of temperatures and heat removal in the emplacement drift. (5) Address general considerations of the effect of water/moisture removal by ventilation on the repository thermal conditions. The numerical modeling in this document will be limited to heat-only modeling and calculations. Only a preliminary assessment of the heat/moisture ventilation effects and modeling method will be performed in this revision. Modeling of moisture effects on heat removal and emplacement drift temperature may be performed in the future

Displacement Ventilation

DEFF Research Database (Denmark)

Nielsen, Peter Vilhelm

Displacement ventilation is an interesting new type of air distribution principle which should be considered in connection with design of comfort ventilation in both smal1 and large spaces. Research activities on displacement ventilation are large all over the world and new knowledge of design...... methods appears continuously. This book gives an easy introduction to the basis of displacement ventilation and the chapters are written in the order which is used in a design procedure. The main text is extended by five appendices which show some of the new research activities taking place at Aalborg...

Computational Fluid Dynamics in Ventilation Design

DEFF Research Database (Denmark)

Nielsen, Peter V.

2008-01-01

This paper is based on the new REHVA Guidebook Computational Fluid  Dynamics in Ventilation Design (Nielsen et al. 2007) written by Peter V. Nielsen, Francis(Nielsen 2007) written by Peter V. Nielsen, Francis Allard, Hazim B. Awbi, Lars Davidson and Alois Schälin. The guidebook is made for people....... The guidebook introduces rules for good quality prediction work, and it is the purpose of the guidebook to improve the technical level of CFD work in ventilation.......This paper is based on the new REHVA Guidebook Computational Fluid  Dynamics in Ventilation Design (Nielsen et al. 2007) written by Peter V. Nielsen, Francis(Nielsen 2007) written by Peter V. Nielsen, Francis Allard, Hazim B. Awbi, Lars Davidson and Alois Schälin. The guidebook is made for people...... who need to use and discuss results based on CFD predictions, and it gives insight into the subject for those who are not used to work with CFD. The guidebook is also written for people working with CFD who have to be more aware of how this numerical method is applied in the area of ventilation...

SU-F-J-219: Predicting Ventilation Change Due to Radiation Therapy: Dependency On Pre-RT Ventilation and Effort Correction

Energy Technology Data Exchange (ETDEWEB)

Patton, T; Du, K; Bayouth, J [University of Wisconsin, Madison, WI (United States); Christensen, G; Reinhardt, J [University of Iowa, Iowa City, IA (United States)

2016-06-15

Purpose: Ventilation change caused by radiation therapy (RT) can be predicted using four-dimensional computed tomography (4DCT) and image registration. This study tested the dependency of predicted post-RT ventilation on effort correction and pre-RT lung function. Methods: Pre-RT and 3 month post-RT 4DCT images were obtained for 13 patients. The 4DCT images were used to create ventilation maps using a deformable image registration based Jacobian expansion calculation. The post-RT ventilation maps were predicted in four different ways using the dose delivered, pre-RT ventilation, and effort correction. The pre-RT ventilation and effort correction were toggled to determine dependency. The four different predicted ventilation maps were compared to the post-RT ventilation map calculated from image registration to establish the best prediction method. Gamma pass rates were used to compare the different maps with the criteria of 2mm distance-to-agreement and 6% ventilation difference. Paired t-tests of gamma pass rates were used to determine significant differences between the maps. Additional gamma pass rates were calculated using only voxels receiving over 20 Gy. Results: The predicted post-RT ventilation maps were in agreement with the actual post-RT maps in the following percentage of voxels averaged over all subjects: 71% with pre-RT ventilation and effort correction, 69% with no pre-RT ventilation and effort correction, 60% with pre-RT ventilation and no effort correction, and 58% with no pre-RT ventilation and no effort correction. When analyzing only voxels receiving over 20 Gy, the gamma pass rates were respectively 74%, 69%, 65%, and 55%. The prediction including both pre- RT ventilation and effort correction was the only prediction with significant improvement over using no prediction (p<0.02). Conclusion: Post-RT ventilation is best predicted using both pre-RT ventilation and effort correction. This is the only prediction that provided a significant

Trigger performance of mid-level ICU mechanical ventilators during assisted ventilation: a bench study.

Science.gov (United States)

Ferreira, Juliana C; Chipman, Daniel W; Kacmarek, Robert M

2008-09-01

To compare the triggering performance of mid-level ICU mechanical ventilators with a standard ICU mechanical ventilator. Experimental bench study. The respiratory care laboratory of a university-affiliated teaching hospital. A computerized mechanical lung model, the IngMar ASL5000. Ten mid-level ICU ventilators were compared to an ICU ventilator at two levels of lung model effort, three combinations of respiratory mechanics (normal, COPD and ARDS) and two modes of ventilation, volume and pressure assist/control. A total of 12 conditions were compared. Performance varied widely among ventilators. Mean inspiratory trigger time was ventilators. The mean inspiratory delay time (time from initiation of the breath to return of airway pressure to baseline) was longer than that for the ICU ventilator for all tested ventilators except one. The pressure drop during triggering (Ptrig) was comparable with that of the ICU ventilator for only two ventilators. Expiratory Settling Time (time for pressure to return to baseline) had the greatest variability among ventilators. Triggering differences among these mid-level ICU ventilators and with the ICU ventilator were identified. Some of these ventilators had a much poorer triggering response with high inspiratory effort than the ICU ventilator. These ventilators do not perform as well as ICU ventilators in patients with high ventilatory demand.

Validating and improving CT ventilation imaging by correlating with ventilation 4D-PET/CT using {sup 68}Ga-labeled nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Kipritidis, John, E-mail: john.kipritidis@sydney.edu.au; Keall, Paul J. [Radiation Physics Laboratory, Sydney Medical School, University of Sydney, Sydney NSW 2006 (Australia); Siva, Shankar [Department of Radiation Oncology, Peter MacCallum Cancer Centre, and Sir Peter MacCallum Department of Oncology, University of Melbourne, Parkville VIC 3052 (Australia); Hofman, Michael S.; Callahan, Jason; Hicks, Rodney J. [Centre for Cancer Imaging, Peter MacCallum Cancer Centre and Department of Medicine, University of Melbourne, Melbourne VIC 3002 (Australia)

2014-01-15

Purpose: CT ventilation imaging is a novel functional lung imaging modality based on deformable image registration. The authors present the first validation study of CT ventilation using positron emission tomography with{sup 68}Ga-labeled nanoparticles (PET-Galligas). The authors quantify this agreement for different CT ventilation metrics and PET reconstruction parameters. Methods: PET-Galligas ventilation scans were acquired for 12 lung cancer patients using a four-dimensional (4D) PET/CT scanner. CT ventilation images were then produced by applying B-spline deformable image registration between the respiratory correlated phases of the 4D-CT. The authors test four ventilation metrics, two existing and two modified. The two existing metrics model mechanical ventilation (alveolar air-flow) based on Hounsfield unit (HU) change (V{sub HU}) or Jacobian determinant of deformation (V{sub Jac}). The two modified metrics incorporate a voxel-wise tissue-density scaling (ρV{sub HU} and ρV{sub Jac}) and were hypothesized to better model the physiological ventilation. In order to assess the impact of PET image quality, comparisons were performed using both standard and respiratory-gated PET images with the former exhibiting better signal. Different median filtering kernels (σ{sub m} = 0 or 3 mm) were also applied to all images. As in previous studies, similarity metrics included the Spearman correlation coefficient r within the segmented lung volumes, and Dice coefficient d{sub 20} for the (0 − 20)th functional percentile volumes. Results: The best agreement between CT and PET ventilation was obtained comparing standard PET images to the density-scaled HU metric (ρV{sub HU}) with σ{sub m} = 3 mm. This leads to correlation values in the ranges 0.22 ⩽ r ⩽ 0.76 and 0.38 ⩽ d{sub 20} ⩽ 0.68, with r{sup ¯}=0.42±0.16 and d{sup ¯}{sub 20}=0.52±0.09 averaged over the 12 patients. Compared to Jacobian-based metrics, HU-based metrics lead to statistically significant

Volume-Targeted Ventilation in the Neonate: Benchmarking Ventilators on an Active Lung Model.

Science.gov (United States)

Krieger, Tobias J; Wald, Martin

2017-03-01

Mechanically ventilated neonates have been observed to receive substantially different ventilation after switching ventilator models, despite identical ventilator settings. This study aims at establishing the range of output variability among 10 neonatal ventilators under various breathing conditions. Relative benchmarking test of 10 neonatal ventilators on an active neonatal lung model. Neonatal ICU. Ten current neonatal ventilators. Ventilators were set identically to flow-triggered, synchronized, volume-targeted, pressure-controlled, continuous mandatory ventilation and connected to a neonatal lung model. The latter was configured to simulate three patients (500, 1,500, and 3,500 g) in three breathing modes each (passive breathing, constant active breathing, and variable active breathing). Averaged across all weight conditions, the included ventilators delivered between 86% and 110% of the target tidal volume in the passive mode, between 88% and 126% during constant active breathing, and between 86% and 120% under variable active breathing. The largest relative deviation occurred during the 500 g constant active condition, where the highest output machine produced 147% of the tidal volume of the lowest output machine. All machines deviate significantly in volume output and ventilation regulation. These differences depend on ventilation type, respiratory force, and patient behavior, preventing the creation of a simple conversion table between ventilator models. Universal neonatal tidal volume targets for mechanical ventilation cannot be transferred from one ventilator to another without considering necessary adjustments.

Thermal comfort and IAQ assessment of under-floor air distribution system integrated with personalized ventilation in hot and humid climate

Energy Technology Data Exchange (ETDEWEB)

Li, Ruixin [Department of Building, National University of Singapore (Singapore); International Centre for Indoor Environment and Energy, Department of Civil Engineering, Technical University of Denmark (Denmark); Sekhar, S.C. [Department of Building, National University of Singapore (Singapore); Melikov, A.K. [International Centre for Indoor Environment and Energy, Department of Civil Engineering, Technical University of Denmark (Denmark)

2010-09-15

The potential for improving occupants' thermal comfort with personalized ventilation (PV) system combined with under-floor air distribution (UFAD) system was explored through human response study. The hypothesis was that cold draught at feet can be reduced when relatively warm air is supplied by UFAD system and uncomfortable sensation as ''warm head'' can be reduced by the PV system providing cool and fresh outdoor air at the facial level. A study with 30 human subjects was conducted in a Field Environmental Chamber. The chamber was served by two dedicated systems - a primary air handling unit (AHU) for 100% outdoor air that is supplied through the PV air terminal devices and a secondary AHU for 100% recirculated air that is supplied through UFAD outlets. Responses of the subjects to the PV-UFAD system were collected at various room air and PV air temperature combinations. The analyses of the results obtained reveal improved acceptability of perceived air quality and improved thermal sensation with PV-UFAD in comparison with the reference case of UFAD alone or mixing ventilation with ceiling supply diffuser. The local thermal sensation at the feet was also improved when warmer UFAD supply air temperature was adopted in the PV-UFAD system. (author)

Characterization of natural ventilation in wastewater collection systems.

Science.gov (United States)

Ward, Matthew; Corsi, Richard; Morton, Robert; Knapp, Tom; Apgar, Dirk; Quigley, Chris; Easter, Chris; Witherspoon, Jay; Pramanik, Amit; Parker, Wayne

2011-03-01

The purpose of the study was to characterize natural ventilation in full-scale gravity collection system components while measuring other parameters related to ventilation. Experiments were completed at four different locations in the wastewater collection systems of Los Angeles County Sanitation Districts, Los Angeles, California, and the King County Wastewater Treatment District, Seattle, Washington. The subject components were concrete gravity pipes ranging in diameter from 0.8 to 2.4 m (33 to 96 in.). Air velocity was measured in each pipe using a carbon-monoxide pulse tracer method. Air velocity was measured entering or exiting the components at vents using a standpipe and hotwire anemometer arrangement. Ambient wind speed, temperature, and relative humidity; headspace temperature and relative humidity; and wastewater flow and temperature were measured. The field experiments resulted in a large database of measured ventilation and related parameters characterizing ventilation in full-scale gravity sewers. Measured ventilation rates ranged from 23 to 840 L/s. The experimental data was used to evaluate existing ventilation models. Three models that were based upon empirical extrapolation, computational fluid dynamics, and thermodynamics, respectively, were evaluated based on predictive accuracy compared to the measured data. Strengths and weaknesses in each model were found and these observations were used to propose a concept for an improved ventilation model.

VENTILATION NEEDS DURING CONSTRUCTION

International Nuclear Information System (INIS)

C.R. Gorrell

1998-01-01

The purpose of this analysis is to determine ventilation needs during construction and development of the subsurface repository and develop systems to satisfy those needs. For this analysis, construction is defined as pre-emplacement excavation and development is excavation that takes place simultaneously with emplacement. The three options presented in the ''Overall Development and Emplacement Ventilation Systems'' analysis (Reference 5.5) for development ventilation will be applied to construction ventilation in this analysis as well as adding new and updated ventilation factors to each option for both construction and development. The objective of this analysis is to develop a preferred ventilation system to support License Application Design. The scope of this analysis includes: (1) Description of ventilation conditions; (2) Ventilation factors (fire hazards, dust control, construction logistics, and monitoring and control systems); (3) Local ventilation alternatives; (4) Global ventilation options; and (5) Evaluation of options

Weaning newborn infants from mechanical ventilation

Directory of Open Access Journals (Sweden)

Paolo Biban

2013-06-01

Full Text Available Invasive mechanical ventilation is a life-saving procedure which is largely used in neonatal intensive care units, particularly in very premature newborn infants. However, this essential treatment may increase mortality and cause substantial morbidity, including lung or airway injuries, unplanned extubations, adverse hemodynamic effects, analgosedative dependency and severe infectious complications, such as ventilator-associated pneumonia. Therefore, limiting the duration of airway intubation and mechanical ventilator support is crucial for the neonatologist, who should aim to a shorter process of discontinuing mechanical ventilation as well as an earlier appreciation of readiness for spontaneous breathing trials. Unfortunately, there is scarce information about the best ways to perform an effective weaning process in infants undergoing mechanical ventilation, thus in most cases the weaning course is still based upon the individual judgment of the attending clinician. Nonetheless, some evidence indicate that volume targeted ventilation modes are more effective in reducing the duration of mechanical ventilation than traditional pressure limited ventilation modes, particularly in very preterm babies. Weaning and extubation directly from high frequency ventilation could be another option, even though its effectiveness, when compared to switching and subsequent weaning and extubating from conventional ventilation, is yet to be adequately investigated. Some data suggest the use of weaning protocols could reduce the weaning time and duration of mechanical ventilation, but better designed prospective studies are still needed to confirm these preliminary observations. Finally, the implementation of short spontaneous breathing tests in preterm infants has been shown to be beneficial in some centres, favoring an earlier extubation at higher ventilatory settings compared with historical controls, without worsening the extubation failure rate. Further

Development of a Residential Integrated Ventilation Controller

Energy Technology Data Exchange (ETDEWEB)

Staff Scientist; Walker, Iain; Sherman, Max; Dickerhoff, Darryl

2011-12-01

The goal of this study was to develop a Residential Integrated Ventilation Controller (RIVEC) to reduce the energy impact of required mechanical ventilation by 20percent, maintain or improve indoor air quality and provide demand response benefits. This represents potential energy savings of about 140 GWh of electricity and 83 million therms of natural gas as well as proportional peak savings in California. The RIVEC controller is intended to meet the 2008 Title 24 requirements for residential ventilation as well as taking into account the issues of outdoor conditions, other ventilation devices (including economizers), peak demand concerns and occupant preferences. The controller is designed to manage all the residential ventilation systems that are currently available. A key innovation in this controller is the ability to implement the concept of efficacy and intermittent ventilation which allows time shifting of ventilation. Using this approach ventilation can be shifted away from times of high cost or high outdoor pollution towards times when it is cheaper and more effective. Simulations, based on the ones used to develop the new residential ventilation requirements for the California Buildings Energy code, were used to further define the specific criteria and strategies needed for the controller. These simulations provide estimates of the energy, peak power and contaminant improvement possible for different California climates for the various ventilation systems. Results from a field test of the prototype controller corroborate the predicted performance.

An open-loop, physiologic model-based decision support system can provide appropriate ventilator settings

DEFF Research Database (Denmark)

Karbing, Dan Stieper; Spadaro, Savino; Dey, Nilanjan

2018-01-01

OBJECTIVES: To evaluate the physiologic effects of applying advice on mechanical ventilation by an open-loop, physiologic model-based clinical decision support system. DESIGN: Prospective, observational study. SETTING: University and Regional Hospitals' ICUs. PATIENTS: Varied adult ICU population...

46 CFR 111.103-1 - Power ventilation systems except machinery space ventilation systems.

Science.gov (United States)

2010-10-01

... 46 Shipping 4 2010-10-01 2010-10-01 false Power ventilation systems except machinery space ventilation systems. 111.103-1 Section 111.103-1 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY... Power ventilation systems except machinery space ventilation systems. Each power ventilation system must...

Mid-Ventilation Concept for Mobile Pulmonary Tumors: Internal Tumor Trajectory Versus Selective Reconstruction of Four-Dimensional Computed Tomography Frames Based on External Breathing Motion

International Nuclear Information System (INIS)

Guckenberger, Matthias; Wilbert, Juergen; Krieger, Thomas; Richter, Anne; Baier, Kurt; Flentje, Michael

2009-01-01

Purpose: To evaluate the accuracy of direct reconstruction of mid-ventilation and peak-phase four-dimensional (4D) computed tomography (CT) frames based on the external breathing signal. Methods and Materials: For 11 patients with 15 pulmonary targets, a respiration-correlated CT study (4D CT) was acquired for treatment planning. After retrospective time-based sorting of raw projection data and reconstruction of eight CT frames equally distributed over the breathing cycle, mean tumor position (P mean ), mid-ventilation frame, and breathing motion were evaluated based on the internal tumor trajectory. Analysis of the external breathing signal (pressure sensor around abdomen) with amplitude-based sorting of projections was performed for direct reconstruction of the mid-ventilation frame and frames at peak phases of the breathing cycle. Results: On the basis of the eight 4D CT frames equally spaced in time, tumor motion was largest in the craniocaudal direction, with 12 ± 7 mm on average. Tumor motion between the two frames reconstructed at peak phases was not different in the craniocaudal and anterior-posterior directions but was systematically smaller in the left-right direction by 1 mm on average. The 3-dimensional distance between P mean and the tumor position in the mid-ventilation frame based on the internal tumor trajectory was 1.2 ± 1 mm. Reconstruction of the mid-ventilation frame at the mean amplitude position of the external breathing signal resulted in tumor positions 2.0 ± 1.1 mm distant from P mean . Breathing-induced motion artifacts in mid-ventilation frames caused negligible changes in tumor volume and shape. Conclusions: Direct reconstruction of the mid-ventilation frame and frames at peak phases based on the external breathing signal was reliable. This makes the reconstruction of only three 4D CT frames sufficient for application of the mid-ventilation technique in clinical practice.

Indoor air quality in mechanically ventilated residential dwellings/low-rise buildings: A review of existing information

DEFF Research Database (Denmark)

Aganovic, Amar; Hamon, Mathieu; Kolarik, Jakub

Mechanical ventilation has become a mandatory requirement in multiple European standards addressing indoor air quality (IAQ) and ventilation in residential dwellings (single family houses and low-rise apartment buildings). This article presents the state of the art study through a review...... of the existing literature, to establish a link between ventilation rate and key indoor air pollutants. Design characteristics of a mechanical ventilation system such as supply/exhaustairflow, system and design of supply and exhaust outlets were considered. The performance of various ventilation solutionswas......-house ventilation rate was reported below 0.5h-1 or 14 l/s·person in bedrooms, the concentrations of the pollutants elevated above minimum threshold limits (CO2>1350 ppm; TVOC >3000 μg/m3) defined by the standard. Insufficient or non-existent supply of air was related to significantly higher pollutant...

[Pressure support ventilation and proportional assist ventilation during weaning from mechanical ventilation].

Science.gov (United States)

Aguirre-Bermeo, H; Bottiroli, M; Italiano, S; Roche-Campo, F; Santos, J A; Alonso, M; Mancebo, J

2014-01-01

To compare tolerance, duration of mechanical ventilation (MV) and clinical outcomes during weaning from MV in patients subjected to either pressure support ventilation (PSV) or proportional assist ventilation (PAV). A prospective, observational study was carried out. Intensive Care Unit. A total of 40 consecutive subjects were allocated to either the PSV or the PAV group until each group contained 20 patients. Patients were included in the study when they met the criteria to begin weaning and the attending physician decided to initiate the weaning process. The physician selected the modality and set the ventilatory parameters. None. Demographic data, respiratory mechanics, ventilatory parameters, duration of MV, and clinical outcomes (reintubation, tracheostomy, mortality). Baseline characteristics were similar in both groups. No significant differences were observed between the PSV and PAV groups in terms of the total duration of MV (10 [5-18] vs. 9 [7-19] days; P=.85), reintubation (5 [31%] vs. 3 [19%]; P=.69), or mortality (4 [20%] vs. 5 [25%] deaths; P=1). Eight patients (40%) in the PSV group and 6 patients (30%) in the PAV group (P=.74) required a return to volume assist-control ventilation due to clinical deterioration. Tolerance, duration of MV and clinical outcomes during weaning from mechanical ventilation were similar in PSV and PAV. Copyright © 2013 Elsevier España, S.L. and SEMICYUC. All rights reserved.

Ventilation in low energy housing retrofits

NARCIS (Netherlands)

Mlecnik, E.

2008-01-01

According to the definition, passive houses in Europe meet a target energy demand for heating of less than 15 kWh per square meter and per year. This low level for the heating demand is based on heating by a small post-heater in the hygienic ventilation system at 52 °C maximum, while the ventilation

Responses to Human Bioeffluents at Levels Recommended by Ventilation Standards

DEFF Research Database (Denmark)

Zhang, Xiaojing; Wargocki, Pawel; Lian, Zhiwei

2017-01-01

The purpose of this study was to examine whether exposure to human bioeffluents, at the levels recommended by the current ventilation standards, would cause any effects on humans. Ten subjects were exposed in a low-emission stainless-steel climate chamber for 4.25 hours. The outdoor air supply rate...... was set to 33 or 4 l/s per person, creating two levels of bioeffluents with carbon dioxide (CO2) at 500 or 1600 ppm. Subjective ratings were collected, cognitive performance was examined and physiological responses were monitored. The results show that exposures to human bioeffluents at ventilation rate...

Ventilation effectiveness

CERN Document Server

Mathisen, Hans Martin; Nielsen, Peter V; Moser, Alfred

2004-01-01

Improving the ventilation effectiveness allows the indoor air quality to be significantly enhanced without the need for higher air changes in the building, thereby avoiding the higher costs and energy consumption associated with increasing the ventilation rates. This Guidebook provides easy-to-understand descriptions of the indices used to mesure the performance of a ventilation system and which indices to use in different cases.

Omnidirectional ventilated acoustic barrier

Science.gov (United States)

Zhang, Hai-long; Zhu, Yi-fan; Liang, Bin; Yang, Jing; Yang, Jun; Cheng, Jian-chun

2017-11-01

As an important problem in acoustics, sound insulation finds applications in a great variety of situations. In the existing schemes, however, there has always been a trade-off between the thinness of sound-insulating devices and their ventilating capabilities, limiting their potentials in the control of low-frequency sound in high ventilation environments. Here, we design and experimentally implement an omnidirectional acoustic barrier with a planar profile, subwavelength thickness ( 0.18 λ ), yet high ventilation. The proposed mechanism is based on the interference between the resonant scattering of discrete states and the background scattering of continuous states which induces a Fano-like asymmetric transmission profile. Benefitting from the binary-structured design of the coiled unit and hollow pipe, it maximally simplifies the design and fabrication while ensuring the ventilation for all the non-resonant units with open tubes. The simulated and measured results agree well, showing the effectiveness of our proposed mechanism to block low frequency sound coming from various directions while allowing 63% of the air flow to pass. We anticipate our design to open routes to design sound insulators and to enable applications in traditionally unattainable cases such as those calling for noise reduction and cooling simultaneously.

Passive Cooling of buildings by night-time ventilation

DEFF Research Database (Denmark)

Artmann, Nikolai; Manz, Heinrich; Heiselberg, Per

coefficients below about 4 W/m2K. Heat transfer during night-time ventilation in case of mixing and displacement ventilation was investigated in a full scale test room at Aalborg University. In the experiments the temperature efficiency of the ventilation was determined. Based on the previous re-sults a method...... are still hesitant to apply passive cooling techniques. As night-time ventilation is highly dependent on climatic conditions, a method for quantifying the climatic cooling potential was developed and the impact of climate warming was investigated. Although a clear decrease was found, significant potential...... will remain, especially if night-time ventilation is applied in combination with other cooling methods. Building energy simulations showed that the performance of night-time ventilation is also affected by the heat transfer at internal room surfaces, as the cooling effect is very limited for heat transfer...

The Effects of Ventilation in Homes on Health

DEFF Research Database (Denmark)

Wargocki, Pawel

2013-01-01

and many of them suffer from deficient experimental design, as well as a lack of proper characterization of actual exposures occurring indoors. Based on the available data, in the reviewed studies, it seems likely that health risks may occur when ventilation rates are below 0.4 air changes per hour...... with existing ventilation systems this positive effect was less evident, probably due to poor performance of the system (too low ventilation rates and/or poor maintenance). Studies are recommended in which exposures are much better characterized (by for example measuring the pollutants indicated by the WHO...... Guidelines for Indoor Air Quality and improving ventilation measurements). Exposures should also be controlled using different ventilation methods for comparison. Future studies should also advance the understanding of how ventilation systems should be operated to achieve optimal performance. These data...

Liquid Ventilation

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Qutaiba A. Tawfic

2011-01-01

Full Text Available Mammals have lungs to breathe air and they have no gills to breath liquids. When the surface tension at the air-liquid interface of the lung increases, as in acute lung injury, scientists started to think about filling the lung with fluid instead of air to reduce the surface tension and facilitate ventilation. Liquid ventilation (LV is a technique of mechanical ventilation in which the lungs are insufflated with an oxygenated perfluorochemical liquid rather than an oxygen-containing gas mixture. The use of perfluorochemicals, rather than nitrogen, as the inert carrier of oxygen and carbon dioxide offers a number of theoretical advantages for the treatment of acute lung injury. In addition, there are non-respiratory applications with expanding potential including pulmonary drug delivery and radiographic imaging. The potential for multiple clinical applications for liquid-assisted ventilation will be clarified and optimized in future. Keywords: Liquid ventilation; perfluorochemicals; perfluorocarbon; respiratory distress; surfactant.

Thermal comfort and indoor air quality in rooms with integrated personalized ventilation and under-floor air distribution systems

DEFF Research Database (Denmark)

Li, Ruixin; Sekhar ., S. C.; Melikov, Arsen Krikor

2011-01-01

A comprehensive study comprising physical measurements and human subject experiments was conducted to explore the potential for improving occupants' thermal comfort and indoor air quality (IAQ) using a personalized ventilation (PV) system combined with an under-floor air distribution(UFAD) system....... The integrated PV-UFAD system, when operated at relatively high temperature of the air supplied from the UFAD system, provided comfortable cooling of the facial region, improved inhaled air quality, and decreased the risk of "cold feet," which is often reported in rooms with UFAD alone. This article explores...... and a secondary AHU for 100% recirculated air that is supplied through UFAD outlets. Velocity and temperature distribution in the chamber were measured. A breathing thermal manikin was used to measure the heat loss from 26 body segments and to determine the equivalent temperature. The responses of 30 human...

An Inter-Personal Information Sharing Model Based on Personalized Recommendations

Science.gov (United States)

Kamei, Koji; Funakoshi, Kaname; Akahani, Jun-Ichi; Satoh, Tetsuji

In this paper, we propose an inter-personal information sharing model among individuals based on personalized recommendations. In the proposed model, we define an information resource as shared between people when both of them consider it important --- not merely when they both possess it. In other words, the model defines the importance of information resources based on personalized recommendations from identifiable acquaintances. The proposed method is based on a collaborative filtering system that focuses on evaluations from identifiable acquaintances. It utilizes both user evaluations for documents and their contents. In other words, each user profile is represented as a matrix of credibility to the other users' evaluations on each domain of interests. We extended the content-based collaborative filtering method to distinguish other users to whom the documents should be recommended. We also applied a concept-based vector space model to represent the domain of interests instead of the previous method which represented them by a term-based vector space model. We introduce a personalized concept-base compiled from each user's information repository to improve the information retrieval in the user's environment. Furthermore, the concept-spaces change from user to user since they reflect the personalities of the users. Because of different concept-spaces, the similarity between a document and a user's interest varies for each user. As a result, a user receives recommendations from other users who have different view points, achieving inter-personal information sharing based on personalized recommendations. This paper also describes an experimental simulation of our information sharing model. In our laboratory, five participants accumulated a personal repository of e-mails and web pages from which they built their own concept-base. Then we estimated the user profiles according to personalized concept-bases and sets of documents which others evaluated. We simulated

The barriers to the prevention of ventilator-associated pneumonia from the perspective of critical care nurses: A qualitative descriptive study.

Science.gov (United States)

Atashi, Vajihe; Yousefi, Hojatollah; Mahjobipoor, Hosein; Yazdannik, Ahmadreza

2018-03-01

The aim of this study was to explore the perspectives of Iranian critical care nurses on the barriers to ventilator-associated pneumonia prevention in intensive care units. Most patients hospitalized in intensive care units need mechanical ventilation. One of the most prevalent and serious complications of mechanical ventilation is ventilator-associated pneumonia. There are different barriers to the prevention of this kind of pneumonia. Qualitative descriptive design was used. In this qualitative study, 23 critical care nurses were recruited via purposive sampling. Semi-structured interviews were done for data collection. The interviews were recorded digitally, transcribed word by word, and analyzed using the inductive content analysis approach. The barriers to the prevention of ventilator-associated pneumonia fell into three main categories, namely nurses' limited professional competence, unfavorable environmental conditions, and passive human resource management. The 10 subcategories of these main categories were unfavorable professional attitude, limited professional knowledge, low job motivation, limited professional accountability, non-standard physical structure, inadequate or inappropriate equipment, heavy workload, staff shortage, inadequate staff training, and ineffective supervision. The barriers to the prevention of ventilator-associated pneumonia in intensive care units are very diverse and complex and include a wide range of interrelated personal, environmental, and organizational barriers. This study created a better understanding of the barriers to ventilator-associated pneumonia prevention. Moreover, highlighted the importance of sufficient resources, adequate staffing level, and contextually-appropriate evidence-based guidelines for effective ventilator-associated pneumonia prevention. © 2017 John Wiley & Sons Ltd.

Comparison of usual and alternative methods to measure height in mechanically ventilated patients: potential impact on protective ventilation.

Science.gov (United States)

Bojmehrani, Azadeh; Bergeron-Duchesne, Maude; Bouchard, Carmelle; Simard, Serge; Bouchard, Pierre-Alexandre; Vanderschuren, Abel; L'Her, Erwan; Lellouche, François

2014-07-01

Protective ventilation implementation requires the calculation of predicted body weight (PBW), determined by a formula based on gender and height. Consequently, height inaccuracy may be a limiting factor to correctly set tidal volumes. The objective of this study was to evaluate the accuracy of different methods in measuring heights in mechanically ventilated patients. Before cardiac surgery, actual height was measured with a height gauge while subjects were standing upright (reference method); the height was also estimated by alternative methods based on lower leg and forearm measurements. After cardiac surgery, upon ICU admission, a subject's height was visually estimated by a clinician and then measured with a tape measure while the subject was supine and undergoing mechanical ventilation. One hundred subjects (75 men, 25 women) were prospectively included. Mean PBW was 61.0 ± 9.7 kg, and mean actual weight was 30.3% higher. In comparison with the reference method, estimating the height visually and using the tape measure were less accurate than both lower leg and forearm measurements. Errors above 10% in calculating the PBW were present in 25 and 40 subjects when the tape measure or visual estimation of height was used in the formula, respectively. With lower leg and forearm measurements, 15 subjects had errors above 10% (P bedridden patients on mechanical ventilation. Alternative methods based on lower leg and forearm measurements are potentially interesting solutions to facilitate the accurate application of protective ventilation. Copyright © 2014 by Daedalus Enterprises.

Ventilation of high-speed flows, an alternating methodology for the ventilator design

International Nuclear Information System (INIS)

Saldarriaga V, Juan G.; Navarrete, J.; Galeano B, Luis A.

1996-01-01

This article is about a research developed at Universidad de los Andes on the ventilation of high velocity flows as prevention against cavitations erosion. The research was a consequence of the results found in the physical model of the Guavio River Hydroelectric Project near Bogota and was based in a general model study of a spillway with ventilation system, which did not represent a particular prototype. In the Guavio study one conclusion was obtained:in every ventilation system there are three unknowns which are the air discharge injected to the water flow (design object variable), the sub pressure under the water jet and the jump length of that jet. In the research those three variables were studied using dimensional analysis and multivariable regressions in order to find a set of three equations that allow the design of this type of structures. The new equations are more general than those reported in technical literature

Heliox allows for lower minute volume ventilation in an animal model of ventilator-induced lung injury.

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Charlotte J Beurskens

Full Text Available BACKGROUND: Helium is a noble gas with a low density, allowing for lower driving pressures and increased carbon dioxide (CO2 diffusion. Since application of protective ventilation can be limited by the development of hypoxemia or acidosis, we hypothesized that therefore heliox facilitates ventilation in an animal model of ventilator-induced lung injury. METHODS: Sprague-Dawley rats (N=8 per group were mechanically ventilated with heliox (50% oxygen; 50% helium. Controls received a standard gas mixture (50% oxygen; 50% air. VILI was induced by application of tidal volumes of 15 mL kg(-1; lung protective ventilated animals were ventilated with 6 mL kg(-1. Respiratory parameters were monitored with a pneumotach system. Respiratory rate was adjusted to maintain arterial pCO2 within 4.5-5.5 kPa, according to hourly drawn arterial blood gases. After 4 hours, bronchoalveolar lavage fluid (BALF was obtained. Data are mean (SD. RESULTS: VILI resulted in an increase in BALF protein compared to low tidal ventilation (629 (324 vs. 290 (181 μg mL(-1; p<0.05 and IL-6 levels (640 (8.7 vs. 206 (8.7 pg mL(-1; p<0.05, whereas cell counts did not differ between groups after this short course of mechanical ventilation. Ventilation with heliox resulted in a decrease in mean respiratory minute volume ventilation compared to control (123 ± 0.6 vs. 146 ± 8.9 mL min(-1, P<0.001, due to a decrease in respiratory rate (22 (0.4 vs. 25 (2.1 breaths per minute; p<0.05, while pCO2 levels and tidal volumes remained unchanged, according to protocol. There was no effect of heliox on inspiratory pressure, while compliance was reduced. In this mild lung injury model, heliox did not exert anti-inflammatory effects. CONCLUSIONS: Heliox allowed for a reduction in respiratory rate and respiratory minute volume during VILI, while maintaining normal acid-base balance. Use of heliox may be a useful approach when protective tidal volume ventilation is limited by the development of

EVALUATION TOOL OF CLIMATE POTENTIAL FOR VENTILATIVE COOLING

DEFF Research Database (Denmark)

Belleri, Annamaria; Psomas, Theofanis Ch.; Heiselberg, Per Kvols

2015-01-01

. Within IEA Annex 62 project, national experts are working on the development of a climate evaluation tool, which aims at assessing the potential of ventilative cooling by taking into account also building envelope thermal properties, internal gains and ventilation needs. The analysis is based on a single......-zone thermal model applied to user-input climatic data on hourly basis. The tool identifies the percentage of hours when natural ventilation can be exploited to assure minimum air change rates required by state of the art research, standards and regulations and the percentage of hours when direct ventilative...

Nasal mask ventilation is better than face mask ventilation in edentulous patients.

Science.gov (United States)

Kapoor, Mukul Chandra; Rana, Sandeep; Singh, Arvind Kumar; Vishal, Vindhya; Sikdar, Indranil

2016-01-01

Face mask ventilation of the edentulous patient is often difficult as ineffective seating of the standard mask to the face prevents attainment of an adequate air seal. The efficacy of nasal ventilation in edentulous patients has been cited in case reports but has never been investigated. Consecutive edentulous adult patients scheduled for surgery under general anesthesia with endotracheal intubation, during a 17-month period, were prospectively evaluated. After induction of anesthesia and administration of neuromuscular blocker, lungs were ventilated with a standard anatomical face mask of appropriate size, using a volume controlled anesthesia ventilator with tidal volume set at 10 ml/kg. In case of inadequate ventilation, the mask position was adjusted to achieve best-fit. Inspired and expired tidal volumes were measured. Thereafter, the face mask was replaced by a nasal mask and after achieving best-fit, the inspired and expired tidal volumes were recorded. The difference in expired tidal volumes and airway pressures at best-fit with the use of the two masks and number of patients with inadequate ventilation with use of the masks were statistically analyzed. A total of 79 edentulous patients were recruited for the study. The difference in expiratory tidal volumes with the use of the two masks at best-fit was statistically significant (P = 0.0017). Despite the best-fit mask placement, adequacy of ventilation could not be achieved in 24.1% patients during face mask ventilation, and 12.7% patients during nasal mask ventilation and the difference was statistically significant. Nasal mask ventilation is more efficient than standard face mask ventilation in edentulous patients.

Transition from in-hospital ventilation to home ventilation: process description and quality indicators

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Kastrup, Marc

2017-12-01

Full Text Available The current demographic development of our society results in an increasing number of elderly patients with chronic diseases being treated in the intensive care unit. A possible long-term consequence of such a treatment is that patients remain dependent on certain invasive organ support systems, such as long-term ventilator dependency. The main goal of this project is to define the transition process between in-hospital and out of hospital (ambulatory ventilator support. A further goal is to identify evidence-based quality indicators to help define and describe this process.This project describes an ideal sequence of processes (process chain, based on the current evidence from the literature. Besides the process chain, key data and quality indicators were described in detail. Due to the limited project timeline, these indicators were not extensively tested in the clinical environment.The results of this project may serve as a solid basis for proof of feasibility and proof of concept investigations, optimize the transition process of ventilator-dependent patients from a clinical to an ambulatory setting, as well as reduce the rate of emergency re-admissions.

Design, Implementation & Assessment of Local Exhaust Ventilation System and dust collectors for crushing unit

Directory of Open Access Journals (Sweden)

Farshid Ghorbani shahna

2015-09-01

Full Text Available Background & objective: Industrial ventilation systems and dust collectors are effective solutions to reduce particulate emissions in the workplace and environmental in mineral processes. In this study, Local Exhaust Ventilation System and dust collectors for control of emitted silica, coke, silicon carbide dusts from crushing unit was designed and evaluated. Methods: : Local Exhaust ventilation system based on standards and guides was designed and implemented after field study of the processes and sources of air pollutants. A set comprised of the four parallel cyclones (Stairmand model and a new design of the scrubber had been used for dust control. After set-up of systems, its effectiveness in reducing the exposure of workers in the workshops and dust collecting were assessed. Results: Test results were significant differences between the concentration of particles in both on and off the ventilation system revealed (P <0.05. The system has been implemented as means of personal exposure to pollutants and environmental emissions were reduced 93.01% and 64.64%, respectively. Also, alone and integrated collection efficiency of cyclone and scrubber, were 94.2%, 59.05% and 97.4%, respectively. The results show good agreement with the values of the parameters ventilation system was designed. Conclusion: Implementation of integrated dust collectors is a good option in industries that have the financial and technical constraints to improve change processes and devices. This method with attainment to health and environmental standards not only can be resolve of the pollution problems, but also will be economically justified of such projects with reduction of depreciation expense and dust recycling.

Recommended Ventilation Strategies for Energy-Efficient Production Homes

Energy Technology Data Exchange (ETDEWEB)

Roberson, J.; Brown, R.; Koomey, J.; Warner, J.; Greenberg, S.

1998-12-01

This report evaluates residential ventilation systems for the U.S. Environmental Protection Agency's (EPA's) ENERGY STAR{reg_sign} Homes program and recommends mechanical ventilation strategies for new, low-infiltration, energy-efficient, single-family, ENERGY STAR production (site-built tract) homes in four climates: cold, mixed (cold and hot), hot humid, and hot arid. Our group in the Energy Analysis Department at Lawrence Berkeley National Lab compared residential ventilation strategies in four climates according to three criteria: total annualized costs (the sum of annualized capital cost and annual operating cost), predominant indoor pressure induced by the ventilation system, and distribution of ventilation air within the home. The mechanical ventilation systems modeled deliver 0.35 air changes per hour continuously, regardless of actual infiltration or occupant window-opening behavior. Based on the assumptions and analysis described in this report, we recommend independently ducted multi-port supply ventilation in all climates except cold because this strategy provides the safety and health benefits of positive indoor pressure as well as the ability to dehumidify and filter ventilation air. In cold climates, we recommend that multi-port supply ventilation be balanced by a single-port exhaust ventilation fan, and that builders offer balanced heat-recovery ventilation to buyers as an optional upgrade. For builders who continue to install forced-air integrated supply ventilation, we recommend ensuring ducts are airtight or in conditioned space, installing a control that automatically operates the forced-air fan 15-20 minutes during each hour that the fan does not operate for heating or cooling, and offering ICM forced-air fans to home buyers as an upgrade.

Implementation of a real-time compliance dashboard to help reduce SICU ventilator-associated pneumonia with the ventilator bundle.

Science.gov (United States)

Zaydfudim, Victor; Dossett, Lesly A; Starmer, John M; Arbogast, Patrick G; Feurer, Irene D; Ray, Wayne A; May, Addison K; Pinson, C Wright

2009-07-01

Ventilator-associated pneumonia (VAP) causes significant morbidity and mortality in critically ill surgical patients. Recent studies suggest that the success of preventive measures is dependent on compliance with ventilator bundle parameters. Implementation of an electronic dashboard will improve compliance with the bundle parameters and reduce rates of VAP in our surgical intensive care unit (SICU). Time series analysis of VAP rates between January 2005 and July 2008, with dashboard implementation in July 2007. Multidisciplinary SICU at a tertiary-care referral center with a stable case mix during the study period. Patients admitted to the SICU between January 2005 and July 2008. Infection control data were used to establish rates of VAP and total ventilator days. For the time series analysis, VAP rates were calculated as quarterly VAP events per 1000 ventilator days. Ventilator bundle compliance was analyzed after dashboard implementation. Differences between expected and observed VAP rates based on time series analysis were used to estimate the effect of intervention. Average compliance with the ventilator bundle improved from 39% in August 2007 to 89% in July 2008 (P dashboard (P = .01). Quarterly VAP rates were significantly reduced in the November 2007 through January 2008 and February through April 2008 periods (P dashboard improved compliance with ventilator bundle measures and is associated with reduced rates of VAP in our SICU.

Survey execution to build a ventilation model, Australian style

Energy Technology Data Exchange (ETDEWEB)

Rowland, J.A. [Dallas Mining Services Pty Ltd., Wollongong, NSW (Australia)

2010-07-01

Ventilation surveys and the development of a properly tuned ventilation model are important components of a modern underground mine safety management system to ensure the safety of miners. Such systems in Australia revolve around the routine application of risk based logic. However, assessing the risk in ventilation systems always changes. Designers of ventilation circuits therefore use ventilation modeling software as a key tool to facilitate the structured process. This paper emphasized the importance of measuring the underground circuit and replicating the measurements in a working model. The most commonly used modeling program in Australia is the Ventsim software which is available as a fully graphical 3D configuration as well as a 2D version. The value of the mine ventilation survey lies in the ability of the data to be accurately replicated on a mine ventilation model. As such, much thought must be given to the ventilation survey scope of work and overall process. The surveys must satisfy operational needs and must delineate the circuit to a level that will allow a model be to accurately assembled in order to determine when minor or major ventilation circuit adjustments are needed. 1 ref., 10 figs.

Ventilation/perfusion SPECT/CT in patients with pulmonary emphysema. Evaluation of software-based analysing.

Science.gov (United States)

Schreiter, V; Steffen, I; Huebner, H; Bredow, J; Heimann, U; Kroencke, T J; Poellinger, A; Doellinger, F; Buchert, R; Hamm, B; Brenner, W; Schreiter, N F

2015-01-01

The purpose of this study was to evaluate the reproducibility of a new software based analysing system for ventilation/perfusion single-photon emission computed tomography/computed tomography (V/P SPECT/CT) in patients with pulmonary emphysema and to compare it to the visual interpretation. 19 patients (mean age: 68.1 years) with pulmonary emphysema who underwent V/P SPECT/CT were included. Data were analysed by two independent observers in visual interpretation (VI) and by software based analysis system (SBAS). SBAS PMOD version 3.4 (Technologies Ltd, Zurich, Switzerland) was used to assess counts and volume per lung lobe/per lung and to calculate the count density per lung, lobe ratio of counts and ratio of count density. VI was performed using a visual scale to assess the mean counts per lung lobe. Interobserver variability and association for SBAS and VI were analysed using Spearman's rho correlation coefficient. Interobserver agreement correlated highly in perfusion (rho: 0.982, 0.957, 0.90, 0.979) and ventilation (rho: 0.972, 0.924, 0.941, 0.936) for count/count density per lobe and ratio of counts/count density in SBAS. Interobserver agreement correlated clearly for perfusion (rho: 0.655) and weakly for ventilation (rho: 0.458) in VI. SBAS provides more reproducible measures than VI for the relative tracer uptake in V/P SPECT/CTs in patients with pulmonary emphysema. However, SBAS has to be improved for routine clinical use.

Potential risk for bacterial contamination in conventional reused ventilator systems and disposable closed ventilator-suction systems.

Science.gov (United States)

Li, Ya-Chi; Lin, Hui-Ling; Liao, Fang-Chun; Wang, Sing-Siang; Chang, Hsiu-Chu; Hsu, Hung-Fu; Chen, Sue-Hsien; Wan, Gwo-Hwa

2018-01-01

Few studies have investigated the difference in bacterial contamination between conventional reused ventilator systems and disposable closed ventilator-suction systems. The aim of this study was to investigate the bacterial contamination rates of the reused and disposable ventilator systems, and the association between system disconnection and bacterial contamination of ventilator systems. The enrolled intubated and mechanically ventilated patients used a conventional reused ventilator system and a disposable closed ventilator-suction system, respectively, for a week; specimens were then collected from the ventilator circuit systems to evaluate human and environmental bacterial contamination. The sputum specimens from patients were also analyzed in this study. The detection rate of bacteria in the conventional reused ventilator system was substantially higher than that in the disposable ventilator system. The inspiratory and expiratory limbs of the disposable closed ventilator-suction system had higher bacterial concentrations than the conventional reused ventilator system. The bacterial concentration in the heated humidifier of the reused ventilator system was significantly higher than that in the disposable ventilator system. Positive associations existed among the bacterial concentrations at different locations in the reused and disposable ventilator systems, respectively. The predominant bacteria identified in the reused and disposable ventilator systems included Acinetobacter spp., Bacillus cereus, Elizabethkingia spp., Pseudomonas spp., and Stenotrophomonas (Xan) maltophilia. Both the reused and disposable ventilator systems had high bacterial contamination rates after one week of use. Disconnection of the ventilator systems should be avoided during system operation to decrease the risks of environmental pollution and human exposure, especially for the disposable ventilator system. ClinicalTrials.gov PRS / NCT03359148.

Protective mechanical ventilation, why use it?

Science.gov (United States)

Seiberlich, Emerson; Santana, Jonas Alves; Chaves, Renata de Andrade; Seiberlich, Raquel Carvalho

2011-01-01

Mechanical ventilation (MV) strategies have been modified over the last decades with a tendency for increasingly lower tidal volumes (VT). However, in patients without acute lung injury (ALI) or acute respiratory distress syndrome (ARDS) the use of high VTs is still very common. Retrospective studies suggest that this practice can be related to mechanical ventilation-associated ALI. The objective of this review is to search for evidence to guide protective MV in patients with healthy lungs and to suggest strategies to properly ventilate lungs with ALI/ARDS. A review based on the main articles that focus on the use of strategies of mechanical ventilation was performed. Consistent studies to determine which would be the best way to ventilate a patient with healthy lungs are lacking. Expert recommendations and current evidence presented in this article indicate that the use of a VT lower than 10 mL.kg(-1), associated with positive end-expiratory pressure (PEEP) ≥ 5 cmH(2)O without exceeding a pressure plateau of 15 to 20 cmH(2)O could minimize alveolar stretching at the end of inspiration and avoid possible inflammation or alveolar collapse. Copyright © 2011 Elsevier Editora Ltda. All rights reserved.

Do new anesthesia ventilators deliver small tidal volumes accurately during volume-controlled ventilation?

Science.gov (United States)

Bachiller, Patricia R; McDonough, Joseph M; Feldman, Jeffrey M

2008-05-01

During mechanical ventilation of infants and neonates, small changes in tidal volume may lead to hypo- or hyperventilation, barotrauma, or volutrauma. Partly because breathing circuit compliance and fresh gas flow affect tidal volume delivery by traditional anesthesia ventilators in volume-controlled ventilation (VCV) mode, pressure-controlled ventilation (PCV) using a circle breathing system has become a common approach to minimizing the risk of mechanical ventilation for small patients, although delivered tidal volume is not assured during PCV. A new generation of anesthesia machine ventilators addresses the problems of VCV by adjusting for fresh gas flow and for the compliance of the breathing circuit. In this study, we evaluated the accuracy of new anesthesia ventilators to deliver small tidal volumes. Four anesthesia ventilator systems were evaluated to determine the accuracy of volume delivery to the airway during VCV at tidal volume settings of 100, 200, and 500 mL under different conditions of breathing circuit compliance (fully extended and fully contracted circuits) and lung compliance. A mechanical test lung (adult and infant) was used to simulate lung compliances ranging from 0.0025 to 0.03 L/cm H(2)O. Volumes and pressures were measured using a calibrated screen pneumotachograph and custom software. We tested the Smartvent 7900, Avance, and Aisys anesthesia ventilator systems (GE Healthcare, Madison, WI) and the Apollo anesthesia ventilator (Draeger Medical, Telford, PA). The Smartvent 7900 and Avance ventilators use inspiratory flow sensors to control the volume delivered, whereas the Aisys and Apollo ventilators compensate for the compliance of the circuit. We found that the anesthesia ventilators that use compliance compensation (Aisys and Apollo) accurately delivered both large and small tidal volumes to the airway of the test lung under conditions of normal and low lung compliance during VCV (ranging from 95.5% to 106.2% of the set tidal volume

Factors Predicting Ventilator Dependence in Patients with Ventilator-Associated Pneumonia

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Chia-Cheng Tseng

2012-01-01

Full Text Available Objectives. To determine risk factors associated with ventilator dependence in patients with ventilator-associated pneumonia (VAP. Study Design. A retrospective study was conducted at Chang Gung Memorial Hospital, Kaohsiung, from January 1, 2007 to January 31, 2008. Methods. This study evaluated 163 adult patients (aged ≥18 years. Eligibility was evaluated according to the criterion for VAP, Sequential Organ Failure Assessment (SOFA score, Acute Physiological Assessment and Chronic Health Evaluation II (APACHE II score. Oxygenation index, underlying comorbidities, septic shock status, previous tracheostomy status, and factors related to pneumonia were collected for analysis. Results. Of the 163 VAP patients in the study, 90 patients survived, yielding a mortality rate of 44.8%. Among the 90 surviving patients, only 36 (40% had been weaned off ventilators at the time of discharge. Multivariate logistic regression analysis was used to identify underlying factors such as congestive cardiac failure (P=0.009, initial high oxygenation index value (P=0.04, increased SOFA scores (P=0.01, and increased APACHE II scores (P=0.02 as independent predictors of ventilator dependence. Results from the Kaplan-Meier method indicate that initial therapy with antibiotics could increase the ventilator weaning rate (log Rank test, P<0.001. Conclusions. Preexisting cardiopulmonary function, high APACHE II and SOFA scores, and high oxygenation index were the strongest predictors of ventilator dependence. Initial empiric antibiotic treatment can improve ventilator weaning rates at the time of discharge.

An air-conditioning, ventilation and automatic ventilation monitoring and recording system constructed in an unsealed radioisotope laboratory. Energy-saving measures in Nagasaki University Radioisotope Center

International Nuclear Information System (INIS)

Takatsuji, Toshihiro; Yoshida, Masahiro; Takao, Hideaki; Okumura, Yutaka; Ooura, Tosinobu; Kotoura, Kazuki; Yamanaka, Yasushi; Yanagita, Hiroyoshi.

1998-01-01

We constructed an automatic operation system of air-conditioners and ventilators in a radiation controlled area to minimize electric consumption. The system operates the air-conditioner and the ventilator of each ventilation unit when someone is staying in rooms belonging to the unit based on information from an access control system to the controlled area and lighting switches in front of individual room. For understanding of operation conditions and confirmation of radioactive concentration in air lower than the legal limit at the ventilation stack, we also constructed an automatic ventilation monitoring and recording system, which makes complete operation records of each ventilator automatically. These systems enabled to achieve sharp energy-saving compatible with radiation protection. (author)

Complications of mechanical ventilation

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Drašković Biljana

2011-01-01

Full Text Available Mechanical ventilation of the lungs, as an important therapeutic measure, cannot be avoided in critically ill patients. However, when machines take over some of vital functions there is always a risk of complications and accidents. Complications associated with mechanical ventilation can be divided into: 1 airway-associated complications; 2 complications in the response of patients to mechanical ventilation; and 3 complications related to the patient’s response to the device for mechanical ventilation. Complications of artificial airway may be related to intubation and extubation or the endotracheal tube. Complications of mechanical ventilation, which arise because of the patient’s response to mechanical ventilation, may primarily cause significant side effects to the lungs. During the last two decades it was concluded that mechanical ventilation can worsen or cause acute lung injury. Mechanical ventilation may increase the alveolar/capillary permeability by overdistension of the lungs (volutrauma, it can exacerbate lung damage due to the recruitment/derecruitment of collapsed alveoli (atelectrauma and may cause subtle damages due to the activation of inflammatory processes (biotrauma. Complications caused by mechanical ventilation, beside those involving the lungs, can also have significant effects on other organs and organic systems, and can be a significant factor contributing to the increase of morbidity and mortality in critically ill of mechanically ventilated patients. Complications are fortunately rare and do not occur in every patient, but due to their seriousness and severity they require extensive knowledge, experience and responsibility by health-care workers.

Accuracy of tidal volume delivered by home mechanical ventilation during mouthpiece ventilation

Science.gov (United States)

Prigent, Helene; Falaize, Line; Leroux, Karl; Santos, Dante; Vaugier, Isabelle; Orlikowski, David; Lofaso, Frederic

2016-01-01

The aim of our study was to evaluate efficacy and reliability of currently available ventilators for mouthpiece ventilation (MPV). Five life-support home ventilators were assessed in a bench test using different settings simulating the specificities of MPV, such as intermittent circuit disconnection and presence of continuous leaks. The intermittent disconnection of the circuit caused relevant swings in the delivered tidal volume (VT), showing a VT overshoot during the disconnection periods and a VT decrease when the interface was reconnected to the test lung. The five ventilators showed substantial differences in the number of respiratory cycles necessary to reach a stable VT in the volume-controlled setting, ranging from 1.3 ± 0.6 to 7.3 ± 1.2 cycles. These differences were less accentuated in the volume-assisted setting (MPV-dedicated mode, when available). Our data show large differences in the capacity of the different ventilators to deal with the rapidly changing respiratory load features that characterize MPV, which can be further accentuated according to the used ventilator setting. The dedicated MPV modes allow improvement in the performance of ventilators only in some defined situations. This has practical consequences for the choice of the ventilator to be used for MPV in a specific patient. PMID:27146811

Exposure Due to Interacting Air flows Between Two Persons

DEFF Research Database (Denmark)

Bjørn, Erik; Nielsen, Peter V.

The contaminant concentration inhaled by an occupant (ie. the personal exposure) is usually less than the return concentration in displacement ventilated rooms. Two main questions are investigated: 1) Does the exhalation from one person penetrate the breathing zone of another person placed nearby...

Characteristics of coal mine ventilation air flows.

Science.gov (United States)

Su, Shi; Chen, Hongwei; Teakle, Philip; Xue, Sheng

2008-01-01

Coal mine methane (CMM) is not only a greenhouse gas but also a wasted energy resource if not utilised. Underground coal mining is by far the most important source of fugitive methane emissions, and approximately 70% of all coal mining related methane is emitted to the atmosphere through mine ventilation air. Therefore, research and development on mine methane mitigation and utilisation now focuses on methane emitted from underground coal mines, in particular ventilation air methane (VAM) capture and utilisation. To date, most work has focused on the oxidation of very low concentration methane. These processes may be classified based on their combustion kinetic mechanisms into thermal oxidation and catalytic oxidation. VAM mitigation/utilisation technologies are generally divided into two basic categories: ancillary uses and principal uses. However, it is possible that the characteristics of ventilation air flows, for example the variations in methane concentration and the presence of certain compounds, which have not been reported so far, could make some potential VAM mitigation and utilisation technologies unfeasible if they cannot cope with the characteristics of mine site ventilation air flows. Therefore, it is important to understand the characteristics of mine ventilation air flows. Moreover, dust, hydrogen sulphide, sulphur dioxide, and other possible compounds emitted through mine ventilation air into the atmosphere are also pollutants. Therefore, this paper presents mine-site experimental results on the characteristics of mine ventilation air flows, including methane concentration and its variations, dust loadings, particle size, mineral matter of the dust, and other compounds in the ventilation air flows. The paper also discusses possible correlations between ventilation air characteristics and underground mining activities.

Oral mask ventilation is more effective than face mask ventilation after nasal surgery.

Science.gov (United States)

Yazicioğlu, Dilek; Baran, Ilkay; Uzumcugil, Filiz; Ozturk, Ibrahim; Utebey, Gulten; Sayın, M Murat

2016-06-01

To evaluate and compare the face mask (FM) and oral mask (OM) ventilation techniques during anesthesia emergence regarding tidal volume, leak volume, and difficult mask ventilation (DMV) incidence. Prospective, randomized, crossover study. Operating room, training and research hospital. American Society of Anesthesiologists physical status I and II adult patients scheduled for nasal surgery. Patients in group FM-OM received FM ventilation first, followed by OM ventilation, and patients in group OM-FM received OM ventilation first, followed by FM ventilation, with spontaneous ventilation after deep extubation. The FM ventilation was applied with the 1-handed EC-clamp technique. The OM was placed only over the mouth, and the 1-handed EC-clamp technique was used again. A child's size FM was used for the OM ventilation technique, the mask was rotated, and the inferior part of the mask was placed toward the nose. The leak volume (MVleak), mean airway pressure (Pmean), and expired tidal volume (TVe) were assessed with each mask technique for 3 consecutive breaths. A mask ventilation grade ≥3 was considered DMV. DMV occurred more frequently during FM ventilation (75% with FM vs 8% with OM). In the FM-first sequence, the mean TVe was 249±61mL with the FM and 455±35mL with the OM (P=.0001), whereas in the OM-first sequence, it was 276±81mL with the FM and 409±37mL with the OM (P=.0001). Regardless of the order used, the OM technique significantly decreased the MVleak and increased the TVe when compared to the FM technique. During anesthesia emergence after nasal surgery the OM may offer an effective ventilation method as it decreases the incidence of DMV and the gas leak around the mask and provides higher tidal volume delivery compared with FM ventilation. Copyright © 2016 Elsevier Inc. All rights reserved.

REVERSIBLE VENTILATION SYSTEM FOR ADMINISTRATIVE BUILDINGS

Directory of Open Access Journals (Sweden)

Valery Yu. Kravchuk

2017-01-01

Full Text Available Abstract. Objectives To consider the possibility of applying the principle of reversing air flows for a centralised ventilation system; to develop a specific scheme for air exchange reversible ventilation, which will take into account the peculiarities of the microclimate of administrative buildings; to select the type of filling of the air-permeable element and justify this choice; to determine the conditions for changing the direction of air movement in the ventilation system and the area of its application; to form a list of equipment necessary for the operation of such a system; to consider the influence of supply and exhaust devices on the heat and humidity regime of claddings. Methods  To achieve this goal, the published thematic material was reviewed and a patent search carried out using Russian and European databases. Data on mathematical modelling of filtration in porous media and experimental results were used. A method for ventilating rooms in administrative building using the reversal of movement of supply and exhaust air streams along the same channels was applied. Results  Schemas for reversible ventilation systems are presented and their modes of operation considered. It is established that the idea of reversing ventilation flows has not yet been applied in the development of centralised ventilation systems. Based on these published materials, it was concluded that the proposed design of supply and exhaust devices can be used in practice. An original air exchange scheme for the ventilation of administrative buildings and design of supply and exhaust devices for this system are proposed. The conditions for changing the operating modes of the system and the scope of its application are determined. Conclusion The use of the proposed ventilation system allows normative air exchange to be provided without using a supply unit during the cold season. This application of airflow reversal allows the potential of natural forces to be used

Dispersion of exhaled droplet nuclei in a two-bed hospital ward with three different ventilation systems

DEFF Research Database (Denmark)

Qian, H.; Li, Y.; Nielsen, Peter V.

2006-01-01

hospital ward with three ventilation systems, i.e. mixing, downward and displacement ventilation. Two life-size breathing thermal manikins were used to simulate a source patient and a receiving patient. The exhalation jet from a bed-lying manikin was visualized using smoke. N2O was used as tracer gas...... are well mixed in the ward. Bed distance does not affect the personal exposure of the receiving patient. For displacement ventilation, the exhaled jet can penetrate a long distance. A high concentration layer of exhaled droplet nuclei because of thermal stratification locking has also been observed...

Ventilation Effectiveness

DEFF Research Database (Denmark)

Mundt, M.; Mathisen, H. M.; Moser, M.

Improving the ventilation effectiveness allows the indoor air quality to be significantly enhanced without the need for higher air changes in the building, thereby avoiding the higher costs and energy consumption associated with increasing the ventilation rates. This Guidebook provides easy-to-un...

Humidification during invasive and noninvasive mechanical ventilation: 2012.

Science.gov (United States)

Restrepo, Ruben D; Walsh, Brian K

2012-05-01

We searched the MEDLINE, CINAHL, and Cochrane Library databases for articles published between January 1990 and December 2011. The update of this clinical practice guideline is based on 184 clinical trials and systematic reviews, and 10 articles investigating humidification during invasive and noninvasive mechanical ventilation. The following recommendations are made following the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) scoring system: 1. Humidification is recommended on every patient receiving invasive mechanical ventilation. 2. Active humidification is suggested for noninvasive mechanical ventilation, as it may improve adherence and comfort. 3. When providing active humidification to patients who are invasively ventilated, it is suggested that the device provide a humidity level between 33 mg H(2)O/L and 44 mg H(2)O/L and gas temperature between 34°C and 41°C at the circuit Y-piece, with a relative humidity of 100%. 4. When providing passive humidification to patients undergoing invasive mechanical ventilation, it is suggested that the HME provide a minimum of 30 mg H(2)O/L. 5. Passive humidification is not recommended for noninvasive mechanical ventilation. 6. When providing humidification to patients with low tidal volumes, such as when lung-protective ventilation strategies are used, HMEs are not recommended because they contribute additional dead space, which can increase the ventilation requirement and P(aCO(2)). 7. It is suggested that HMEs are not used as a prevention strategy for ventilator-associated pneumonia.

Perioperative lung protective ventilation in obese patients.

Science.gov (United States)

Fernandez-Bustamante, Ana; Hashimoto, Soshi; Serpa Neto, Ary; Moine, Pierre; Vidal Melo, Marcos F; Repine, John E

2015-05-06

The perioperative use and relevance of protective ventilation in surgical patients is being increasingly recognized. Obesity poses particular challenges to adequate mechanical ventilation in addition to surgical constraints, primarily by restricted lung mechanics due to excessive adiposity, frequent respiratory comorbidities (i.e. sleep apnea, asthma), and concerns of postoperative respiratory depression and other pulmonary complications. The number of surgical patients with obesity is increasing, and facing these challenges is common in the operating rooms and critical care units worldwide. In this review we summarize the existing literature which supports the following recommendations for the perioperative ventilation in obese patients: (1) the use of protective ventilation with low tidal volumes (approximately 8 mL/kg, calculated based on predicted -not actual- body weight) to avoid volutrauma; (2) a focus on lung recruitment by utilizing PEEP (8-15 cmH2O) in addition to recruitment maneuvers during the intraoperative period, as well as incentivized deep breathing and noninvasive ventilation early in the postoperative period, to avoid atelectasis, hypoxemia and atelectrauma; and (3) a judicious oxygen use (ideally less than 0.8) to avoid hypoxemia but also possible reabsorption atelectasis. Obesity poses an additional challenge for achieving adequate protective ventilation during one-lung ventilation, but different lung isolation techniques have been adequately performed in obese patients by experienced providers. Postoperative efforts should be directed to avoid hypoventilation, atelectasis and hypoxemia. Further studies are needed to better define optimum protective ventilation strategies and analyze their impact on the perioperative outcomes of surgical patients with obesity.

REGIONAL DEPOSITION OF COARSE PARTICLES AND VENTILATION DISTRIBUTION IN PATIENTS WITH CYSTIC FIBROSIS

Science.gov (United States)

The efficacy of inhaled pharmaceuticals depends, in part, on their site of respiratory deposition. Markedly nonuniform ventilation distribution may occur in persons with obstructive airways diseases and may affect particle deposition. We studied the relationship between regional ...

Transitions to Home Mechanical Ventilation: The Experiences of Canadian Ventilator-Assisted Adults and Their Family Caregivers.

Science.gov (United States)

Dale, Craig M; King, Judy; Nonoyama, Mika; Carbone, Sarah; McKim, Douglas; Road, Jeremy; Rose, Louise

2017-12-28

Several studies have explored the experience of ventilator-assisted individual (VAIs) living at home with family caregivers. However, few explore the experiences of these individuals as they transition from a hospital setting to living at home with a view to identifying modifiable processes that could optimize transition. This descriptive, qualitative study sought to elucidate barriers to, and facilitators of, transition to home mechanical ventilation (HMV) from the perspective of Canadian VAIs and their family caregivers. Participant recruitment occurred through hospital and community respiratory clinicians based in the four Canadian provinces of Alberta, British Columbia, Ontario, and Saskatchewan. Semi-structured telephone or face-to-face interviews at home were undertaken with 33 individuals including 19 VAIs and 14 family caregivers between 3 to 24 months of transitioning to HMV. Interview data was analyzed using content analysis. Formal teaching of knowledge and skills relevant to HMV within the hospital setting prior to transition was perceived as having an immediate and enduring positive impact on transition. However, family-clinician conflict, information gaps, and persistent lack of trained personal support workers (PSWs) to provide care in the home contributed to maladjustment relating to transition. Participants strongly recommended improved transitional care in the form of respiratory health professional telephone support, home outreach, in addition to training of PSWs. Transition to HMV is a complex and demanding process. Extended HMV training and support may be helpful in mediating adjustment challenges thus reducing stress, caregiver burden and improving health related quality of life for VAIs and family caregivers.

Performance evaluation of ventilation radiators

International Nuclear Information System (INIS)

Myhren, Jonn Are; Holmberg, Sture

2013-01-01

A ventilation radiator is a combined ventilation and heat emission unit currently of interest due to its potential for increasing energy efficiency in exhaust-ventilated buildings with warm water heating. This paper presents results of performance tests of several ventilation radiator models conducted under controlled laboratory conditions. The purpose of the study was to validate results achieved by Computational Fluid Dynamics (CFD) in an earlier study and identify possible improvements in the performance of such systems. The main focus was on heat transfer from internal convection fins, but comfort and health aspects related to ventilation rates and air temperatures were also considered. The general results from the CFD simulations were confirmed; the heat output of ventilation radiators may be improved by at least 20% without sacrificing ventilation efficiency or thermal comfort. Improved thermal efficiency of ventilation radiators allows a lower supply water temperature and energy savings both for heating up and distribution of warm water in heat pumps or district heating systems. A secondary benefit is that a high ventilation rate can be maintained all year around without risk for cold draught. -- Highlights: ► Low temperature heat emitters are currently of interest due to their potential for increasing energy efficiency. ► A ventilation radiator is a combined ventilation and heat emission unit which can be adapted to low temperature heating systems. ► We examine how ventilation radiators can be made to be more efficient in terms of energy consumption and thermal comfort. ► Current work focuses on heat transfer mechanisms and convection fin configuration of ventilation radiators

Design Principles for Hybrid Ventilation

DEFF Research Database (Denmark)

Heiselberg, Per

For many years mechanical and natural ventilation systems have developed separately. Naturally, the next step in this development is the development of ventilation concepts that utilize and combine the best features from each system to create a new type of ventilation system -Hybrid Ventilation. ....... The hybrid ventilation concepts, design challenges and - principles are discussed and illustrated by four building examples....

Thermal Comfort in a Naturally-Ventilated Educational Building

Directory of Open Access Journals (Sweden)

David Mwale Ogoli

2012-11-01

Full Text Available A comprehensive study of thermal comfort in a naturally ventilated education building (88,000 ft2 in a Chicago suburb will be conducted with 120 student subjects in 2007. This paper discusses some recent trends in worldwide thermal comfort studies and presents a proposal of research for this building through a series of questionnaire tables. Two research methods used inthermal comfort studies are field studies and laboratory experiments in climate-chambers. The various elements that constitute a “comfortable” thermal environment include physical factors (ambient air temperature, mean radiant temperature, air movement and humidity, personal factors(activity and clothing, classifications (gender, age, education, etc. and psychological expectations (knowledge, experience, psychological effect of visual warmth by, say, a fireplace. Comparisons are made using data gathered from Nairobi, Kenya.Keywords: Comfort, temperature, humidity and ventilation

Residential ventilation standards scoping study

Energy Technology Data Exchange (ETDEWEB)

McKone, Thomas E.; Sherman, Max H.

2003-10-01

The goals of this scoping study are to identify research needed to develop improved ventilation standards for California's Title 24 Building Energy Efficiency Standards. The 2008 Title 24 Standards are the primary target for the outcome of this research, but this scoping study is not limited to that timeframe. We prepared this scoping study to provide the California Energy Commission with broad and flexible options for developing a research plan to advance the standards. This document presents the findings of a scoping study commissioned by the Public Interest Energy Research (PIER) program of the California Energy Commission to determine what research is necessary to develop new residential ventilation requirements for California. This study is one of three companion efforts needed to complete the job of determining the ventilation needs of California residences, determining the bases for setting residential ventilation requirements, and determining appropriate ventilation technologies to meet these needs and requirements in an energy efficient manner. Rather than providing research results, this scoping study identifies important research questions along with the level of effort necessary to address these questions and the costs, risks, and benefits of pursuing alternative research questions. In approaching these questions and corresponding levels of effort, feasibility and timing were important considerations. The Commission has specified Summer 2005 as the latest date for completing this research in time to update the 2008 version of California's Energy Code (Title 24).

Design Procedure for Hybrid Ventilation

DEFF Research Database (Denmark)

Heiselberg, Per; Tjelflaat, Per Olaf

Mechanical and natural ventilation systems have developed separately during many years. The natural next step in this development is development of ventilation concepts that utilises and combines the best features from each system into a new type of ventilation system - Hybrid Ventilation....... Buildings with hybrid ventilation often include other sustainable technologies and an energy optimisation requires an integrated approach in the design of the building and its mechanical systems. Therefore, the hybrid ventilation design procedure differs from the design procedure for conventional HVAC....... The first ideas on a design procedure for hybrid ventilation is presented and the different types of design methods, that is needed in different phases of the design process, is discussed....

Optimized ventilation-on-demand (VOD)

Energy Technology Data Exchange (ETDEWEB)

Masse, M. [Simsmart Technologies Inc., Brossard, PQ (Canada); Cervinka, A. [Newtrax Technologies Inc., Montreal, PQ (Canada)

2008-07-01

This presentation described how the combination of 2 innovative technologies can help optimize mine ventilation. Newtrax Technologies has developed a self-contained battery-powered wireless electronic system designed to operate in harsh industrial environments, including underground mines. Simsmart Technologies has created an advanced process and control simulation based design tool used in industrial applications, including mine ventilation systems. This presentation described the system components and how they work. These included the wireless mesh network designed for dynamic diesel machinery tracking and operating status monitoring; the real-time ventilation model and fan speed optimizer; the OPC server for information interchange; the OPC linkage to existing control infrastructure; a human machine interface that provide data archiving capability; live MS-Excel to interrogate the simulation, controls and optimizer; and, the battery-powered network mesh that provides SCADA functionality to route optimized setpoints. Details of the user interface were also provided. 1 tab., 20 figs.

Trend analysis of hospital resource utilization for prolonged mechanical ventilation patients in Taiwan: a population-based study.

Science.gov (United States)

Hung, Tien-Chiung; Lai, Yung-Fa; Tseng, Ching-Wan; Hong, Yong-Han; Shi, Hon-Yi

2013-04-01

The aging Taiwan population is expected to require vast medical resources, including prolonged mechanical ventilation (PMV). This study determined the trends in hospital resource utilization and associated factors in PMV patients in Taiwan. All patients who had received mechanical ventilation for > 21 days (International Classification of Diseases, 9th Revision, Clinical Modification codes 518.81-518.89) during 2004-2007 were recruited to the study. Administrative claims data obtained from the Bureau of National Health Insurance of Taiwan were analyzed. The study analyzed 65,181 patients who had received PMV during 2004-2007. The number of PMVs per 100,000 persons was 94.30 in 2004, and it gradually decreased to 89.38 in 2007, which was a change rate of -5.22%. During the study period, stay significantly decreased, from 35.12 days to 31.61 days, whereas hospital treatment costs significantly increased, from $7,933.17 to $8,257.52 (P providers and patients should recognize that attributes of both the patient and the hospital may affect hospital resource utilization. Additionally, these analytical results should be applicable to similar populations in other countries.

Ventilation on demand (VOD) projects : Vale Inco Ltd.

Energy Technology Data Exchange (ETDEWEB)

Allen, C.L. [Vale Inco Ltd., Sudbury, ON (Canada)

2008-07-01

This paper presented a dynamic ventilation on Demand (VOD) system that is in the developmental stages at Vale Inco. The VOD addresses the need to minimize ventilation costs associated with mining at depth. The physical components of the system are in the process of being tested at Vale Inco's mine sites in Sudbury, Ontario, where the company operates 6 base metal mines that vary in depth from 1200 metres to 2400 metres. Two pilot projects are simultaneously testing the physical components of the VOD system at Coleman and Creighton mines. A Scope of Work is also being finalized in which the architecture of the system is being optimized for testing a prototype dynamic VOD installation. The primary ventilation systems at the mines were described along with future ventilation requirements and air flow regulations with reference to both conventional and automated regulators. The development of the VOD system involved software development, computer networking, electrical planning, PLC programming and accurate ventilation modeling. The common objective was to reduce ventilation cost and increase production in the mine by maximizing the efficiency of the ventilation system. This will be accomplished through communication training and following safety standards and protocols. 7 refs., 2 tabs., 6 figs.

Method to assess the performance of domestic ventilation systems considering the influence of uncertainties

NARCIS (Netherlands)

Yang, Z.

2012-01-01

The ventilation system plays an important role in the indoor environment of a domestic building. A ventilation system is normally designed based on the national or regional regulations. Although ventilation systems are designed based on the same design rules, performance deviations between different

Comparison of ventilation and cardiac compressions using the Impact Model 730 automatic transport ventilator compared to a conventional bag valve with a facemask in a model of adult cardiopulmonary arrest.

Science.gov (United States)

Salas, Nichole; Wisor, Bernadette; Agazio, Janice; Branson, Richard; Austin, Paul N

2007-07-01

To determine the performance of two person CPR on an instrumented manikin by registered nurses using conventional bag valve mask (BVM) ventilation or the Impact Model 730 automatic transport ventilator (Impact 730, Impact Instrumentation, Inc., West Caldwell, NJ) in CPR mode using a face mask. Randomized crossover quasi-experimental. Laboratory simulation. Twenty-eight registered nurses trained in performing adult cardiopulmonary resuscitation (CPR). Basic Life Support was provided by subjects using a conventional bag valve mask (BVM) ventilation or mask ventilation with an automatic transport ventilator, the Impact 730, which incorporates a metronome to facilitate chest compression timing. Subjects alternated performing 4min of CPR using the BVM or Impact 730 to deliver breaths with a mask while the other subject performed compressions. Flow, volume and pressure were measured using a pneumotachograph and pressure transducer, and ease of use was measured using a 10cm visual analogue scale. There was no statistical or clinical difference between the actual and recommended tidal lung volume (mean+/-S.D.) delivered by the Impact 730 (-120.4+/-91.5ml) versus the BVM (-119.8+/-187.3+/-ml). Ventilation with the BVM resulted in more (137.7+/-143.9ml) air per breath passing through the simulated lower esophageal sphincter compared to the Impact 730 (14.0+/-16.8ml, pCPR in a simulated setting.

Influence of Restrictive Ventilation Impairment on Physical Function and Activities of Homebound Elderly Persons

Directory of Open Access Journals (Sweden)

Jun Horie

2011-06-01

Conclusions: Although patients with restrictive ventilation impairment were unlikely to be aware of their disorder, degradation in systemic stamina had already commenced. It appears that maintaining exercise habits prevented degradation of not only instantaneous walking ability but also of systemic stamina.

Modes of mechanical ventilation for the operating room.

Science.gov (United States)

Ball, Lorenzo; Dameri, Maddalena; Pelosi, Paolo

2015-09-01

Most patients undergoing surgical procedures need to be mechanically ventilated, because of the impact of several drugs administered at induction and during maintenance of general anaesthesia on respiratory function. Optimization of intraoperative mechanical ventilation can reduce the incidence of post-operative pulmonary complications and improve the patient's outcome. Preoxygenation at induction of general anaesthesia prolongs the time window for safe intubation, reducing the risk of hypoxia and overweighs the potential risk of reabsorption atelectasis. Non-invasive positive pressure ventilation delivered through different interfaces should be considered at the induction of anaesthesia morbidly obese patients. Anaesthesia ventilators are becoming increasingly sophisticated, integrating many functions that were once exclusive to intensive care. Modern anaesthesia machines provide high performances in delivering the desired volumes and pressures accurately and precisely, including assisted ventilation modes. Therefore, the physicians should be familiar with the potential and pitfalls of the most commonly used intraoperative ventilation modes: volume-controlled, pressure-controlled, dual-controlled and assisted ventilation. Although there is no clear evidence to support the advantage of any one of these ventilation modes over the others, protective mechanical ventilation with low tidal volume and low levels of positive end-expiratory pressure (PEEP) should be considered in patients undergoing surgery. The target tidal volume should be calculated based on the predicted or ideal body weight rather than on the actual body weight. To optimize ventilation monitoring, anaesthesia machines should include end-inspiratory and end-expiratory pause as well as flow-volume loop curves. The routine administration of high PEEP levels should be avoided, as this may lead to haemodynamic impairment and fluid overload. Higher PEEP might be considered during surgery longer than 3 h

Analysis of radon reduction by ventilation in uranium mines in China

International Nuclear Information System (INIS)

Hu Penghua; Li Xianjie

2011-01-01

Mine ventilation is the most important way to reduce radon in uranium mines. At present, the concentrations of radon and its daughters in underground air is 3-5 times higher than those in other countries, at the same protection conditions. In this paper, through the analysis of radon reduction status in Chinese uranium mines and the comparison of advantages and shortcomings between variety of ventilation and radon reduction measures, the reasons for higher radon and radon daughter concentration in Chinese uranium mines are discussed and some problems are put forward in three aspects: radon reduction ventilation theory, measures and management. Based on above problems, this paper puts forward some proposals and measures, such as strengthening examination and verification and monitoring practical situation, making clear ventilation plan, training ventilation technician, enhancing ventilation system management, developing radon reduction ventilation research and putting ventilation equipment in place as soon as possible in future. (authors)

Trends in mechanical ventilation: are we ventilating our patients in the best possible way?

Directory of Open Access Journals (Sweden)

Raffaele L. Dellaca’

2017-06-01

To learn how mechanical ventilation developed in recent decades and to provide a better understanding of the actual technology and practice. To learn how and why interdisciplinary research and competences are necessary for providing the best ventilation treatment to patients. To understand which are the most relevant technical limitations in modern mechanical ventilators that can affect their performance in delivery of the treatment. To better understand and classify ventilation modes. To learn the classification, benefits, drawbacks and future perspectives of automatic ventilation tailoring algorithms.

Standardization of pulmonary ventilation technique using volume-controlled ventilators in rats with congenital diaphragmatic hernia

Directory of Open Access Journals (Sweden)

Rodrigo Melo Gallindo

Full Text Available OBJECTIVE: To standardize a technique for ventilating rat fetuses with Congenital Diaphragmatic Hernia (CDH using a volume-controlled ventilator. METHODS: Pregnant rats were divided into the following groups: a control (C; b exposed to nitrofen with CDH (CDH; and c exposed to nitrofen without CDH (N-. Fetuses of the three groups were randomly divided into the subgroups ventilated (V and non-ventilated (N-V. Fetuses were collected on day 21.5 of gestation, weighed and ventilated for 30 minutes using a volume-controlled ventilator. Then the lungs were collected for histological study. We evaluated: body weight (BW, total lung weight (TLW, left lung weight (LLW, ratios TLW / BW and LLW / BW, morphological histology of the airways and causes of failures of ventilation. RESULTS: BW, TLW, LLW, TLW / BW and LLW / BW were higher in C compared with N- (p 0.05. The morphology of the pulmonary airways showed hypoplasia in groups N- and CDH, with no difference between V and N-V (p <0.05. The C and N- groups could be successfully ventilated using a tidal volume of 75 ìl, but the failure of ventilation in the CDH group decreased only when ventilated with 50 ìl. CONCLUSION: Volume ventilation is possible in rats with CDH for a short period and does not alter fetal or lung morphology.

The growing role of noninvasive ventilation in patients requiring prolonged mechanical ventilation.

Science.gov (United States)

Hess, Dean R

2012-06-01

For many patients with chronic respiratory failure requiring ventilator support, noninvasive ventilation (NIV) is preferable to invasive support by tracheostomy. Currently available evidence does not support the use of nocturnal NIV in unselected patients with stable COPD. Several European studies have reported benefit for high intensity NIV, in which setting of inspiratory pressure and respiratory rate are selected to achieve normocapnia. There have also been studies reporting benefit for the use of NIV as an adjunct to exercise training. NIV may be useful as an adjunct to airway clearance techniques in patients with cystic fibrosis. Accumulating evidence supports the use of NIV in patients with obesity hypoventilation syndrome. There is considerable observational evidence supporting the use of NIV in patients with chronic respiratory failure related to neuromuscular disease, and one randomized controlled trial reported that the use of NIV was life-prolonging in patients with amyotrophic lateral sclerosis. A variety of interfaces can be used to provide NIV in patients with stable chronic respiratory failure. The mouthpiece is an interface that is unique in this patient population, and has been used with success in patients with neuromuscular disease. Bi-level pressure ventilators are commonly used for NIV, although there are now a new generation of intermediate ventilators that are portable, have a long battery life, and can be used for NIV and invasive applications. Pressure support ventilation, pressure controlled ventilation, and volume controlled ventilation have been used successfully for chronic applications of NIV. New modes have recently become available, but their benefits await evidence to support their widespread use. The success of NIV in a given patient population depends on selection of an appropriate patient, selection of an appropriate interface, selection of an appropriate ventilator and ventilator settings, the skills of the clinician, the

A historical perspective on ventilator management.

Science.gov (United States)

Shapiro, B A

1994-02-01

Paralysis via neuromuscular blockade in ICU patients requires mechanical ventilation. This review historically addresses the technological advances and scientific information upon which ventilatory management concepts are based, with special emphasis on the influence such concepts have had on the use of neuromuscular blocking agents. Specific reference is made to the scientific information and technological advances leading to the newer concepts of ventilatory management. Information from > 100 major studies in the peer-reviewed medical literature, along with the author's 25 yrs of clinical experience and academic involvement in acute respiratory care is presented. Nomenclature related to ventilatory management is specifically defined and consistently utilized to present and interpret the data. Pre-1970 ventilatory management is traced from the clinically unacceptable pressure-limited devices to the reliable performance of volume-limited ventilators. The scientific data and rationale that led to the concept of relatively large tidal volume delivery are reviewed in the light of today's concerns regarding alveolar overdistention, control-mode dyssynchrony, and auto-positive end-expiratory pressure. Also presented are the post-1970 scientific rationales for continuous positive airway pressure/positive end-expiratory pressure therapy, avoidance of alveolar hyperxia, and partial ventilatory support techniques (intermittent mandatory ventilation/synchronized intermittent mandatory ventilation). The development of pressure-support devices is discussed and the capability of pressure-control techniques is presented. The rationale for more recent concepts of total ventilatory support to avoid ventilator-induced lung injury is presented. The traditional techniques utilizing volume-preset ventilators with relatively large tidal volumes remain valid and desirable for the vast majority of patients requiring mechanical ventilation. Neuromuscular blockade is best avoided in these

VENTILATION TECHNOLOGY SYSTEMS ANALYSIS

Science.gov (United States)

The report gives results of a project to develop a systems analysis of ventilation technology and provide a state-of-the-art assessment of ventilation and indoor air quality (IAQ) research needs. (NOTE: Ventilation technology is defined as the hardware necessary to bring outdoor ...

Using a Ventilation Controller to Optimize Residential Passive Ventilation For Energy and Indoor Air Quality

Energy Technology Data Exchange (ETDEWEB)

Turner, William [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Walker, Iain [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

2014-08-01

One way to reduce the energy impact of providing residential ventilation is to use passive and hybrid systems. However, these passive and hybrid (sometimes called mixed-mode) systems must still meet chronic and acute health standards for ventilation. This study uses a computer simulation approach to examine the energy and indoor air quality (IAQ) implications of passive and hybrid ventilation systems, in 16 California climate zones. Both uncontrolled and flow controlled passive stacks are assessed. A new hybrid ventilation system is outlined that uses an intelligent ventilation controller to minimise energy use, while ensuring chronic and acute IAQ standards are met. ASHRAE Standard 62.2-2010 – the United States standard for residential ventilation - is used as the chronic standard, and exposure limits for PM_2.5, formaldehyde and NO₂ are used as the acute standards.The results show that controlled passive ventilation and hybrid ventilation can be used in homes to provide equivalent IAQ to continuous mechanical ventilation, for less use of energy.

Performance comparison of 15 transport ventilators.

Science.gov (United States)

Chipman, Daniel W; Caramez, Maria P; Miyoshi, Eriko; Kratohvil, Joseph P; Kacmarek, Robert M

2007-06-01

Numerous mechanical ventilators are designed and marketed for use in patient transport. The complexity of these ventilators differs considerably, but very few data exist to compare their operational capabilities. Using bench and animal models, we studied 15 currently available transport ventilators with regard to their physical characteristics, gas consumption (duration of an E-size oxygen cylinder), battery life, ease of use, need for compressed gas, ability to deliver set ventilation parameters to a test lung under 3 test conditions, and ability to maintain ventilation and oxygenation in normal and lung-injured sheep. Most of the ventilators tested were relatively simple to operate and had clearly marked controls. Oxygen cylinder duration ranged from 30 min to 77 min. Battery life ranged from 70 min to 8 hours. All except 3 of the ventilators were capable of providing various F(IO2) values. Ten of the ventilators had high-pressure and patient-disconnect alarms. Only 6 of the ventilators were able to deliver all settings as specifically set on the ventilator during the bench evaluation. Only 4 of the ventilators were capable of maintaining ventilation, oxygenation, and hemodynamics in both the normal and the lung-injured sheep. Only 2 of the ventilators met all the trial targets in all the bench and animal tests. With many of the ventilators, certain of the set ventilation parameters were inaccurate (differed by > 10% from the values from a cardiopulmonary monitor). The physical characteristics and high gas consumption of some of these ventilators may render them less desirable for patient transport.

46 CFR 45.131 - Ventilators.

Science.gov (United States)

2010-10-01

... 46 Shipping 2 2010-10-01 2010-10-01 false Ventilators. 45.131 Section 45.131 Shipping COAST GUARD....131 Ventilators. (a) Ventilators passing through superstructures other than enclosed superstructures must have coamings of steel or equivalent material at the freeboard deck. (b) Ventilators in position 1...

Magnetic Resonance Imaging of Ventilation and Perfusion in the Lung

Science.gov (United States)

Prisk, Gordon Kim (Inventor); Hopkins, Susan Roberta (Inventor); Buxton, Richard Bruce (Inventor); Pereira De Sa, Rui Carlos (Inventor); Theilmann, Rebecca Jean (Inventor); Cronin, Matthew Vincent (Inventor)

2017-01-01

Methods, devices, and systems are disclosed for implementing a fully quantitative non-injectable contrast proton MRI technique to measure spatial ventilation-perfusion (VA/Q) matching and spatial distribution of ventilation and perfusion. In one aspect, a method using MRI to characterize ventilation and perfusion in a lung includes acquiring an MR image of the lung having MR data in a voxel and obtaining a breathing frequency parameter, determining a water density value, a specific ventilation value, and a perfusion value in at least one voxel of the MR image based on the MR data and using the water density value to determine an air content value, and determining a ventilation-perfusion ratio value that is the product of the specific ventilation value, the air content value, the inverse of the perfusion value, and the breathing frequency.

Use of Respiratory Support in the Biphase Ventilation Airway Mode in the Newborn

Directory of Open Access Journals (Sweden)

S. N. Koval

2006-01-01

Full Text Available Biphasic positive airway pressure (BIPAP (also known as DuoPAP, BiLevel, BiVent, PCV+, SPAP is a mode of ventilation with cycling variations between two continuous positive airway pressure levels. It is a mixture of pressure controlled ventilation and spontaneous breathing, which is unrestricted in each phase of the respiratory cycle. The volume displacement caused by the difference between Phigh and Plow airway pressure level. The phase time ratio (PTR — the BIPAP frequency is calculated as the ratio between the durations of the two pressure phases, a PTR greater than 1:1 is called APRV (airway pressure release ventilation. In patients with ARDS maintained spontaneous breathing with BIPAP resulted in lower venous admixture and better arterial blood oxygenation as compared with A/C. Only a few studies with BIPAP have been performed in newborn and infants until now. We studied the use of BIPAP in newborn (body mass > 3kg and randomised 40 patients with respiratory failure for ventilation with BIPAP (n=20 or conventional mechanical ventilatory support (assist-control A/C — synchronised intermittent mandatory ventilation (SIMV (n=20. The Pediatric Risk of Mortality score (PRISM were collected for each patient. Fentanyl, diazepam, GABA were used as sedatives and adjusted in accordance with the Cook scale. We compared ventilatory parameters, information pertaining to pulmonary function and oxygen delivery, cardiac output, additional descriptors of organ system functions, duration and complications of ventilation and number and dosages of sedatives administered. All the patients that we intended to ventilate with BIPAP were successfully ventilated, we can conclude that biphasic ventilatory support suitable mode of ventilation for newborn with a decreased need of analgetics and sedatives than A/C. Finally, BIPAP is an a effective safe, and easy to use for personal mode of mechanical ventilatory support in newborn. 

Simultaneousness of room heating and ventilation air heating

International Nuclear Information System (INIS)

Mathisen, Hans Martin

2006-01-01

The report is part of NTNU-SINTEF's Smart Buildings program, Smart Energy Efficient Buildings (2002-2006), subprogram 3.1 Heating, ventilation and cooling systems. An important part of this subprogram is the development and implementation of heating distribution systems with low return temperature. A comparison has been made of the simultaneousness of room heating and ventilation air heating in six buildings. Existing measuring data with hourly measurements of effect requirements for the different purposes have been employed. Based on the measuring data the relation between the requirements for room heating and ventilation is estimated. A 'fictitious' return temperature has also been estimated. The result shows a significant variation between the buildings. For all there are short periods where the efficiency need for room heating and ventilation is equal (ml)

Uncertainties in different level assessments of domestic ventilation systems

NARCIS (Netherlands)

Bokel, R.M.J.; Yang, Z.; Cauberg, J.J.M.

2013-01-01

In order to improve the quality of ventilation systems, assessments are widely used. In this paper, 3 main assessment levels are distinguished based on the number of ventilation systems to be assessed and the assessment objective. The main assessment levels distinguished in this paper are global

Natural Ventilation in Atria

DEFF Research Database (Denmark)

Svidt, Kjeld; Heiselberg, Per; Hendriksen, Ole Juhl

This case study comprises a monitoring programme as well as a Computational Fluid Dynamics (CFD) analysis of a natural ventilated atrium. The purpose has been to analyse the performance of a typical natural ventilation system in Denmark under both summer and winter conditions.......This case study comprises a monitoring programme as well as a Computational Fluid Dynamics (CFD) analysis of a natural ventilated atrium. The purpose has been to analyse the performance of a typical natural ventilation system in Denmark under both summer and winter conditions....

Ventilation practices in subarachnoid hemorrhage: a cohort study exploring the use of lung protective ventilation.

Science.gov (United States)

Marhong, Jonathan D; Ferguson, Niall D; Singh, Jeffrey M

2014-10-01

Acute respiratory distress syndrome (ARDS) is common following aneurysmal subarachnoid hemorrhage (SAH), but the influence of mechanical ventilator settings on its development is unclear. We sought to determine adherence to lung protective thresholds in ventilated patients with SAH and describe the association between ventilator settings and subsequent development of ARDS. We conducted a retrospective cohort study of consecutive patients receiving mechanical ventilation within 72 h of SAH at a single academic center. Ventilator settings and blood gas data were collected twice daily for the first 7 days of ventilation along with ICU and hospital outcomes. Lung protective ventilation was defined as follows: tidal volume ≤8 mL/kg of predicted body weight, positive end-expiratory pressure (PEEP) ≥5 cm H(2)O, and peak or plateau pressure ≤30 cm H(2)O. The development of ARDS was ascertained retrospectively by PaO(2)/FiO(2) ≤300 with new bilateral lung opacities on chest X-ray within one day of hypoxemia. We identified 62 patients who underwent early mechanical ventilation following SAH. PS and Continuous Positive Airway Pressure were common ventilator modes with a median tidal volume of 7.8 mL/kg [interquartile range 6.8-8.8], median peak pressure of 14 cm H(2)O [IQR 12-17], and median PEEP of 5 cm H(2)O [IQR 5-6]. Adherence to tidal volumes ≤8 mL/kg was seen in 64 % of all observations and peak pressures protective criteria were seen in 58 % of all observations. Thirty-one patients (50 %) were determined to have ARDS. ARDS patients were more frequently ventilated with a peak pressure >30 cm H(2)O (11.3 % of ARDS ventilation days vs. 0 % of non-ARDS ventilation days; p mechanical ventilation frequently breathe spontaneously, generating tidal volumes above usual protective thresholds regardless of meeting ARDS criteria. In patients with SAH, the presence of an additional ARDS risk factor should prompt close screening for the development of ARDS and

Ventilation System Effectiveness and Tested Indoor Air Quality Impacts

Energy Technology Data Exchange (ETDEWEB)

Rudd, Armin [National Renewable Energy Lab. (NREL), Golden, CO (United States); Bergey, Daniel [National Renewable Energy Lab. (NREL), Golden, CO (United States)

2014-02-01

Ventilation system effectiveness testing was conducted at two unoccupied, single-family, detached lab homes at the University of Texas - Tyler. Five ventilation system tests were conducted with various whole-building ventilation systems. Multizone fan pressurization testing characterized building and zone enclosure leakage. PFT testing showed multizone air change rates and interzonal airflow. Cumulative particle counts for six particle sizes, and formaldehyde and other Top 20 VOC concentrations were measured in multiple zones. The testing showed that single-point exhaust ventilation was inferior as a whole-house ventilation strategy. It was inferior because the source of outside air was not direct from outside, the ventilation air was not distributed, and no provision existed for air filtration. Indoor air recirculation by a central air distribution system can help improve the exhaust ventilation system by way of air mixing and filtration. In contrast, the supply and balanced ventilation systems showed that there is a significant benefit to drawing outside air from a known outside location, and filtering and distributing that air. Compared to the Exhaust systems, the CFIS and ERV systems showed better ventilation air distribution and lower concentrations of particulates, formaldehyde and other VOCs. System improvement percentages were estimated based on four System Factor Categories: Balance, Distribution, Outside Air Source, and Recirculation Filtration. Recommended System Factors could be applied to reduce ventilation fan airflow rates relative to ASHRAE Standard 62.2 to save energy and reduce moisture control risk in humid climates. HVAC energy savings were predicted to be 8-10%, or $50-$75/year.

Ventilation System Effectiveness and Tested Indoor Air Quality Impacts

Energy Technology Data Exchange (ETDEWEB)

Rudd, Armin [Building Science Corporation, Somerville, MA (United States); Bergey, Daniel [Building Science Corporation, Somerville, MA (United States)

2014-02-01

In this project, Building America research team Building Science Corporation tested the effectiveness of ventilation systems at two unoccupied, single-family, detached lab homes at the University of Texas - Tyler. Five ventilation system tests were conducted with various whole-building ventilation systems. Multizone fan pressurization testing characterized building and zone enclosure leakage. PFT testing showed multizone air change rates and interzonal airflow. Cumulative particle counts for six particle sizes, and formaldehyde and other Top 20 VOC concentrations were measured in multiple zones. The testing showed that single-point exhaust ventilation was inferior as a whole-house ventilation strategy. This was because the source of outside air was not direct from outside, the ventilation air was not distributed, and no provision existed for air filtration. Indoor air recirculation by a central air distribution system can help improve the exhaust ventilation system by way of air mixing and filtration. In contrast, the supply and balanced ventilation systems showed that there is a significant benefit to drawing outside air from a known outside location, and filtering and distributing that air. Compared to the exhaust systems, the CFIS and ERV systems showed better ventilation air distribution and lower concentrations of particulates, formaldehyde and other VOCs. System improvement percentages were estimated based on four system factor categories: balance, distribution, outside air source, and recirculation filtration. Recommended system factors could be applied to reduce ventilation fan airflow rates relative to ASHRAE Standard 62.2 to save energy and reduce moisture control risk in humid climates. HVAC energy savings were predicted to be 8-10%, or $50-$75/year.

Interfaces and ventilator settings for long-term noninvasive ventilation in COPD patients

Directory of Open Access Journals (Sweden)

Callegari J

2017-06-01

Full Text Available Jens Callegari,1 Friederike Sophie Magnet,1 Steven Taubner,1 Melanie Berger,2 Sarah Bettina Schwarz,1 Wolfram Windisch,1 Jan Hendrik Storre3,4 1Department of Pneumology, Cologne-Merheim Hospital, Kliniken der Stadt Koeln, Witten/Herdecke University Hospital, 2Department of Pneumology, Malteser Hospital St Hildegardis, Cologne, 3Department of Pneumology, University Medical Hospital, Freiburg, 4Department of Intensive Care, Sleep Medicine and Mechanical Ventilation, Asklepios Fachkliniken Munich-Gauting, Gauting, Germany Introduction: The establishment of high-intensity (HI noninvasive ventilation (NIV that targets elevated PaCO2 has led to an increase in the use of long-term NIV to treat patients with chronic hypercapnic COPD. However, the role of the ventilation interface, especially in more aggressive ventilation strategies, has not been systematically assessed.Methods: Ventilator settings and NIV compliance were assessed in this prospective cross-sectional monocentric cohort study of COPD patients with pre-existing NIV. Daytime ­arterialized blood gas analyses and lung function testing were also performed. The primary end point was the distribution among study patients of interfaces (full-face masks [FFMs] vs nasal masks [NMs] in a real-life setting.Results: The majority of the 123 patients studied used an FFM (77%, while 23% used an NM. Ventilation settings were as follows: mean ± standard deviation (SD inspiratory positive airway pressure (IPAP was 23.2±4.6 mbar and mean ± SD breathing rate was 16.7±2.4/minute. Pressure support ventilation (PSV mode was used in 52.8% of patients, while assisted pressure-controlled ventilation (aPCV was used in 47.2% of patients. Higher IPAP levels were associated with an increased use of FFMs (IPAP <21 mbar: 73% vs IPAP >25 mbar: 84%. Mean compliance was 6.5 hours/day, with no differences between FFM (6.4 hours/day and NM (6.7 hours/day users. PaCO2 assessment of ventilation quality revealed

Behovstyret ventilation

DEFF Research Database (Denmark)

Afshari, Alireza; Heiselberg, Per; Reinhold, Claus

2010-01-01

I en nylig afsluttet undersøgelse er der udført en række målinger på otte udvalgte børneinstitutioner. Fire af disse med mekanisk ventilation og fire med naturlig ventilation. Formålet er at udvide den erfaringsbaserede viden om funktionen af naturlige og mekaniske ventilationsløsninger i...

Mechanical ventilator - infants

Science.gov (United States)

... this page: //medlineplus.gov/ency/article/007240.htm Mechanical ventilator - infants To use the sharing features on this page, please enable JavaScript. A mechanical ventilator is a machine that assists with breathing. ...

Comparison between conventional and protective one-lung ventilation for ventilator-assisted thoracic surgery.

Science.gov (United States)

Ahn, H J; Kim, J A; Yang, M; Shim, W S; Park, K J; Lee, J J

2012-09-01

Recent papers suggest protective ventilation (PV) as a primary ventilation strategy during one-lung ventilation (OLV) to reduce postoperative pulmonary morbidity. However, data regarding the advantage of the PV strategy in patients with normal preoperative pulmonary function are inconsistent, especially in the case of minimally invasive thoracic surgery. Therefore we compared conventional OLV (VT 10 ml/kg, FiO2 1.0, zero PEEP) to protective OLV (VT 6 ml/kg, FiO2 0.5, PEEP 5 cmH2O) in patients with normal preoperative pulmonary function tests undergoing video-assisted thoracic surgery. Oxygenation, respiratory mechanics, plasma interleukin-6 and malondialdehyde levels were measured at baseline, 15 and 60 minutes after OLV and 15 minutes after restoration of two-lung ventilation. PaO2 and PaO2/FiO2 were higher in conventional OLV than in protective OLV (PProtective ventilation did not provide advantages over conventional ventilation for video-assisted thoracic surgery in this group of patients with normal lung function.

Ventilation of nuclear facilities

International Nuclear Information System (INIS)

1982-01-01

In this work an examination is made of ventilation problems in nuclear installations, of the fuel cycle or the handling of radioactive compounds. The study covers the detection of radioactive aerosols, purification, iodine trapping, ventilation equipment and its maintenance, engineering, safety of ventilation, fire efficiency, operation, regulations and normalization [fr

Subglottic secretion drainage for the prevention of ventilator-associated pneumonia: a systematic review and meta-analysis.

Science.gov (United States)

Muscedere, John; Rewa, Oleksa; McKechnie, Kyle; Jiang, Xuran; Laporta, Denny; Heyland, Daren K

2011-08-01

Aspiration of secretions containing bacterial pathogens into the lower respiratory tract is the main cause of ventilator-associated pneumonia. Endotracheal tubes with subglottic secretion drainage can potentially reduce this and, therefore, the incidence of ventilator-associated pneumonia. New evidence on subglottic secretion drainage as a preventive measure for ventilator-associated pneumonia has been recently published and to consider the evidence in totality, we conducted an updated systematic review and meta-analysis. We searched computerized databases, reference lists, and personal files. We included randomized clinical trials of mechanically ventilated patients comparing standard endotracheal tubes to those with subglottic secretion drainage and reporting on the occurrence of ventilator-associated pneumonia. Studies were meta-analyzed for the primary outcome of ventilator-associated pneumonia and secondary clinical outcomes. We identified 13 randomized clinical trials that met the inclusion criteria with a total of 2442 randomized patients. Of the 13 studies, 12 reported a reduction in ventilator-associated pneumonia rates in the subglottic secretion drainage arm; in meta-analysis, the overall risk ratio for ventilator-associated pneumonia was 0.55 (95% confidence interval, 0.46-0.66; p drainage was associated with reduced intensive care unit length of stay (-1.52 days; 95% confidence interval, -2.94 to -0.11; p = .03); decreased duration of mechanically ventilated (-1.08 days; 95% confidence interval, -2.04 to -0.12; p = .03), and increased time to first episode of ventilator-associated pneumonia (2.66 days; 95% confidence interval, 1.06-4.26; p = .001). There was no effect on adverse events or on hospital or intensive care unit mortality. In those at risk for ventilator-associated pneumonia, the use of endotracheal tubes with subglottic secretion drainage is effective for the prevention of ventilator-associated pneumonia and may be associated with reduced

Ventilation and air-conditioning system for PWR nuclear power plant

International Nuclear Information System (INIS)

Ohmoto, Kenji

1987-01-01

This report outlines the ventilation and air conditioning facilities for PWR nuclear power plant as well as design re-evaluation and optimization of ventilation and air-conditioning. The primary PWR installations are generally housed in the nuclear reactor building, auxiliary buildings and control building, which are equipped with their own ventilation and air-conditioning systems to serve for their specific purposes. A ventilation/air-conditioning system should be able to work effectively not only for maintaining the ordinary reactor operation but also for controlling the environmental temperature in the event of an accident. Designing of a ventilation/air-conditioning system relied on empirical data in the past, but currently it is performed based on information obtained from various analyses to optimize the system configuration and ventilation capacity. Design re-evaluation of ventilation/air-conditioning systems are conducted widely in various areas, aiming at the integration of safety systems, optimum combination of air-cooling and water-cooling systems, and optimization of the ventilation rate for controlling the concentrations of radioactive substances in the atmosphere in the facilities. It is pointed out that performance evaluation of ventilation/air-conditioning systems, which has been conducted rather macroscopically, should be carried out more in detal in the future to determine optimum air streams and temperature distribution. (Nogami, K.)

Liquid ventilation.

Science.gov (United States)

Sarkar, Suman; Paswan, Anil; Prakas, S

2014-01-01

Human have lungs to breathe air and they have no gills to breath liquids like fish. When the surface tension at the air-liquid interface of the lung increases as in acute lung injury, scientists started to think about filling the lung with fluid instead of air to reduce the surface tension and facilitate ventilation. Liquid ventilation (LV) is a technique of mechanical ventilation in which the lungs are insufflated with an oxygenated perfluorochemical liquid rather than an oxygen-containing gas mixture. The use of perfluorochemicals, rather than nitrogen as the inert carrier of oxygen and carbon dioxide offers a number of advantages for the treatment of acute lung injury. In addition, there are non-respiratory applications with expanding potential including pulmonary drug delivery and radiographic imaging. It is well-known that respiratory diseases are one of the most common causes of morbidity and mortality in intensive care unit. During the past few years several new modalities of treatment have been introduced. One of them and probably the most fascinating, is of LV. Partial LV, on which much of the existing research has concentrated, requires partial filling of lungs with perfluorocarbons (PFC's) and ventilation with gas tidal volumes using conventional mechanical ventilators. Various physico-chemical properties of PFC's make them the ideal media. It results in a dramatic improvement in lung compliance and oxygenation and decline in mean airway pressure and oxygen requirements. No long-term side-effect reported.

Variation in Definition of Prolonged Mechanical Ventilation.

Science.gov (United States)

Rose, Louise; McGinlay, Michael; Amin, Reshma; Burns, Karen Ea; Connolly, Bronwen; Hart, Nicholas; Jouvet, Philippe; Katz, Sherri; Leasa, David; Mawdsley, Cathy; McAuley, Danny F; Schultz, Marcus J; Blackwood, Bronagh

2017-10-01

Consistency of definitional criteria for terminology applied to describe subject cohorts receiving mechanical ventilation within ICU and post-acute care settings is important for understanding prevalence, risk stratification, effectiveness of interventions, and projections for resource allocation. Our objective was to quantify the application and definition of terms for prolonged mechanical ventilation. We conducted a scoping review of studies (all designs except single-case study) reporting a study population (adult and pediatric) using the term prolonged mechanical ventilation or a synonym. We screened 5,331 references, reviewed 539 full-text references, and excluded 120. Of the 419 studies (representing 38 countries) meeting inclusion criteria, 297 (71%) reported data on a heterogeneous subject cohort, and 66 (16%) included surgical subjects only (46 of those 66, 70% cardiac surgery). Other studies described COPD (16, 4%), trauma (22, 5%), neuromuscular (17, 4%), and sepsis (1, 0.2%) cohorts. A total of 741 terms were used to refer to the 419 study cohorts. The most common terms were: prolonged mechanical ventilation (253, 60%), admission to specialized unit (107, 26%), and long-term mechanical ventilation (79, 19%). Some authors (282, 67%) defined their cohorts based on duration of mechanical ventilation, with 154 studies (55%) using this as the sole criterion. We identified 37 different durations of ventilation ranging from 5 h to 1 y, with > 21 d being the most common (28 of 282, 7%). For studies describing a surgical cohort, minimum ventilation duration required for inclusion was ≥ 24 h for 20 of 66 studies (30%). More than half of all studies (237, 57%) did not provide a reason/rationale for definitional criteria used, with only 28 studies (7%) referring to a consensus definition. We conclude that substantial variation exists in the terminology and definitional criteria for cohorts of subjects receiving prolonged mechanical ventilation. Standardization of

Ventilation, indoor air quality, and human health and comfort in dwellings and day-care centers

Energy Technology Data Exchange (ETDEWEB)

Ruotsalainen, R.

1995-12-31

The objective of the study was to assess the actual ventilation and indoor air quality in the Finnish building stock (dwellings and day-care centers) with special reference to the existing guideline values. Furthermore, the objective was to evaluate the occurrence of symptoms and perceptions among occupants (adult residents, children, workers) in relation to ventilation system, ventilation rate and dampness. The measurements of ventilation and indoor air quality in the dwellings and day-care centers included ventilation rate, CO{sub 2} concentration, and temperature and humidity. Self- and parent-administered questionnaires were distributed to the occupants inquiring their personal characteristics, occurrence of symptoms of interest, perceived indoor air quality and details of their home and work environments. Airflows and air change rates varied remarkably both in the dwellings and day-care centers. In the majority of the dwellings and day-care centers, the Finnish guideline values of ventilation rates were not achieved. No consistent associations were observed between the magnitude of mechanical ventilation rates and the occurrence of eye, respiratory, skin and general symptoms, that is, symptoms of sick building syndrome (SBS) among the day-care workers. The results indicate that there is much room for improvement in the ventilation and indoor air quality of Finnish dwellings and day-care centers. The control of ventilation, temperature and humidity and the prevention of water damage are important issues on which to concentrate in the future. There is need to improve the quality in all phases of construction: design, installation, adjustment, operation, and maintenance

Ventilation, indoor air quality, and human health and comfort in dwellings and day-care centers

Energy Technology Data Exchange (ETDEWEB)

Ruotsalainen, R

1996-12-31

The objective of the study was to assess the actual ventilation and indoor air quality in the Finnish building stock (dwellings and day-care centers) with special reference to the existing guideline values. Furthermore, the objective was to evaluate the occurrence of symptoms and perceptions among occupants (adult residents, children, workers) in relation to ventilation system, ventilation rate and dampness. The measurements of ventilation and indoor air quality in the dwellings and day-care centers included ventilation rate, CO{sub 2} concentration, and temperature and humidity. Self- and parent-administered questionnaires were distributed to the occupants inquiring their personal characteristics, occurrence of symptoms of interest, perceived indoor air quality and details of their home and work environments. Airflows and air change rates varied remarkably both in the dwellings and day-care centers. In the majority of the dwellings and day-care centers, the Finnish guideline values of ventilation rates were not achieved. No consistent associations were observed between the magnitude of mechanical ventilation rates and the occurrence of eye, respiratory, skin and general symptoms, that is, symptoms of sick building syndrome (SBS) among the day-care workers. The results indicate that there is much room for improvement in the ventilation and indoor air quality of Finnish dwellings and day-care centers. The control of ventilation, temperature and humidity and the prevention of water damage are important issues on which to concentrate in the future. There is need to improve the quality in all phases of construction: design, installation, adjustment, operation, and maintenance

Bilevel vs ICU ventilators providing noninvasive ventilation: effect of system leaks: a COPD lung model comparison.

Science.gov (United States)

Ferreira, Juliana C; Chipman, Daniel W; Hill, Nicholas S; Kacmarek, Robert M

2009-08-01

Noninvasive positive-pressure ventilation (NPPV) modes are currently available on bilevel and ICU ventilators. However, little data comparing the performance of the NPPV modes on these ventilators are available. In an experimental bench study, the ability of nine ICU ventilators to function in the presence of leaks was compared with a bilevel ventilator using the IngMar ASL5000 lung simulator (IngMar Medical; Pittsburgh, PA) set at a compliance of 60 mL/cm H(2)O, an inspiratory resistance of 10 cm H(2)O/L/s, an expiratory resistance of 20 cm H(2)O/ L/s, and a respiratory rate of 15 breaths/min. All of the ventilators were set at 12 cm H(2)O pressure support and 5 cm H(2)O positive end-expiratory pressure. The data were collected at baseline and at three customized leaks. At baseline, all of the ventilators were able to deliver adequate tidal volumes, to maintain airway pressure, and to synchronize with the simulator, without missed efforts or auto-triggering. As the leak was increased, all of the ventilators (except the Vision [Respironics; Murrysville, PA] and Servo I [Maquet; Solna, Sweden]) needed adjustment of sensitivity or cycling criteria to maintain adequate ventilation, and some transitioned to backup ventilation. Significant differences in triggering and cycling were observed between the Servo I and the Vision ventilators. The Vision and Servo I were the only ventilators that required no adjustments as they adapted to increasing leaks. There were differences in performance between these two ventilators, although the clinical significance of these differences is unclear. Clinicians should be aware that in the presence of leaks, most ICU ventilators require adjustments to maintain an adequate tidal volume.

Air Distribution and Ventilation Effectiveness in a room with Floor/Ceiling Heating and Mixing/Displacement Ventilation

DEFF Research Database (Denmark)

Wu, Xiaozhou; Fang, Lei; Olesen, Bjarne W.

2014-01-01

vertical air temperature differences and air velocities for different hybrid systems are less than 3 C and 0.2 m/s when supply air temperature is 19 C, air change rate is 4.2 h-1, and heated surface temperature of floor/ceiling heating system is 25 C. Ventilation effectiveness of mixing ventilation system...... combined with floor/ceiling heating systems is approximately equal to 1.0, and ventilation effectiveness of displacement ventilation system combined with floor/ceiling heating systems ranges from 1.0 to 1.2. The floor/ceiling heating systems combined with mixing ventilation system have more uniform indoor...... air distribution but smaller ventilation effectiveness compared with the floor/ceiling heating systems combined with displacement ventilation system. With regard to the building heat loss increased by non-uniform indoor air distribution and small ventilation effectiveness, there should be an optimal...

Pleural liquid and kinetic friction coefficient of mesothelium after mechanical ventilation.

Science.gov (United States)

Bodega, Francesca; Sironi, Chiara; Porta, Cristina; Zocchi, Luciano; Agostoni, Emilio

2015-01-15

Volume and protein concentration of pleural liquid in anesthetized rabbits after 1 or 3h of mechanical ventilation, with alveolar pressure equal to atmospheric at end expiration, were compared to those occurring after spontaneous breathing. Moreover, coefficient of kinetic friction between samples of visceral and parietal pleura, obtained after spontaneous or mechanical ventilation, sliding in vitro at physiological velocity under physiological load, was determined. Volume of pleural liquid after mechanical ventilation was similar to that previously found during spontaneous ventilation. This finding is contrary to expectation of Moriondo et al. (2005), based on measurement of lymphatic and interstitial pressure. Protein concentration of pleural liquid after mechanical ventilation was also similar to that occurring after spontaneous ventilation. Coefficient of kinetic friction after mechanical ventilation was 0.023±0.001, similar to that obtained after spontaneous breathing. Copyright © 2014 Elsevier B.V. All rights reserved.

Assessment of Natural Ventilation Potential for Residential Buildings across Different Climate Zones in Australia

Directory of Open Access Journals (Sweden)

Zijing Tan

2017-09-01

Full Text Available In this study, the natural ventilation potential of residential buildings was numerically investigated based on a typical single-story house in the three most populous climate zones in Australia. Simulations using the commercial simulation software TRNSYS (Transient System Simulation Tool were performed for all seasons in three representative cities, i.e., Darwin for the hot humid summer and warm winter zone, Sydney for the mild temperate zone, and Melbourne for the cool temperate zone. A natural ventilation control strategy was generated by the rule-based decision-tree method based on the local climates. Natural ventilation hour (NVH and satisfied natural ventilation hour (SNVH were employed to evaluate the potential of natural ventilation in each city considering local climate and local indoor thermal comfort requirements, respectively. The numerical results revealed that natural ventilation potential was related to the local climate. The greatest natural ventilation potential for the case study building was observed in Darwin with an annual 4141 SNVH out of 4728 NVH, while the least natural ventilation potential was found in the Melbourne case. Moreover, summer and transition seasons (spring and autumn were found to be the optimal periods to sustain indoor thermal comfort by utilising natural ventilation in Sydney and Melbourne. By contrast, natural ventilation was found applicable over the whole year in Darwin. In addition, the indoor operative temperature results demonstrated that indoor thermal comfort can be maintained only by utilising natural ventilation for all cases during the whole year, except for the non-natural ventilation periods in summer in Darwin and winter in Melbourne. These findings could improve the understanding of natural ventilation potential in different climates, and are beneficial for the climate-conscious design of residential buildings in Australia.

Intraoperative mechanical ventilation strategies in patients undergoing one-lung ventilation: a meta-analysis.

Science.gov (United States)

Liu, Zhen; Liu, Xiaowen; Huang, Yuguang; Zhao, Jing

2016-01-01

Postoperative pulmonary complications (PPCs), which are not uncommon in one-lung ventilation, are among the main causes of postoperative death after lung surgery. Intra-operative ventilation strategies can influence the incidence of PPCs. High tidal volume (V T) and increased airway pressure may lead to lung injury, while pressure-controlled ventilation and lung-protective strategies with low V T may have protective effects against lung injury. In this meta-analysis, we aim to investigate the effects of different ventilation strategies, including pressure-controlled ventilation (PCV), volume-controlled ventilation (VCV), protective ventilation (PV) and conventional ventilation (CV), on PPCs in patients undergoing one-lung ventilation. We hypothesize that both PV with low V T and PCV have protective effects against PPCs in one-lung ventilation. A systematic search (PubMed, EMBASE, the Cochrane Library, and Ovid MEDLINE; in May 2015) was performed for randomized trials comparing PCV with VCV or comparing PV with CV in one-lung ventilation. Methodological quality was evaluated using the Cochrane tool for risk. The primary outcome was the incidence of PPCs. The secondary outcomes included the length of hospital stay, intraoperative plateau airway pressure (Pplateau), oxygen index (PaO2/FiO2) and mean arterial pressure (MAP). In this meta-analysis, 11 studies (436 patients) comparing PCV with VCV and 11 studies (657 patients) comparing PV with CV were included. Compared to CV, PV decreased the incidence of PPCs (OR 0.29; 95 % CI 0.15-0.57; P < 0.01) and intraoperative Pplateau (MD -3.75; 95 % CI -5.74 to -1.76; P < 0.01) but had no significant influence on the length of hospital stay or MAP. Compared to VCV, PCV decreased intraoperative Pplateau (MD -1.46; 95 % CI -2.54 to -0.34; P = 0.01) but had no significant influence on PPCs, PaO2/FiO2 or MAP. PV with low V T was associated with the reduced incidence of PPCs compared to CV. However, PCV and VCV had similar

Impact of Fire Ventilation on General Ventilation in the Building

Science.gov (United States)

Zender-Świercz, Ewa; Telejko, Marek

2017-10-01

The fire of building is a threat to its users. The biggest threat is generation, during lifetime of fire, hot gases and smoke. The purpose of quick and efficient evacuation from the area covered by the fire, at first step the escape routes have to be secured from smokiness. The smoke ventilation systems are used for this purpose. The proper design and execution of smoke ventilation is important not only because of the safety, but also of the maintenance of comfort in the building at a time when there is no fire. The manuscript presents the effect of incorrectly realized smoke ventilation in the stairwell of the medium building. The analysis shows that the flaps of smoke ventilation located in the stairwell may have a significant impact on the proper functioning of mechanical ventilation in the period when there is no fire. The improperly installed or incorrect insulated components cause perturbation of air flow and they change pressure distribution in the building. The conclusion of the analysis is the need to include the entire technical equipment of the building during the design and realization of its individual elements. The impact of various installations at each other is very important, and the omission of any of them can cause disturbances in the proper work of another.

Comprehensive evaluation on rationality of ventilation system in uranium underground mine

International Nuclear Information System (INIS)

Zhou Qinglin

1991-01-01

A new method is presented for evaluating rationality of uranium mine ventilation system using fuzzy mathematics. The mathematical models for fuzzy comprehensive evaluation are introduced. Based on practice of uranium mine ventilation, the evaluation factors and the evaluation procedure are given. Using the presented method, a comprehensive evaluation was carried out for ventilation systems before and after regulation in Fuzhou Uranium Mine

Trends in mechanical ventilation: are we ventilating our patients in the best possible way?

Science.gov (United States)

Dellaca', Raffaele L; Veneroni, Chiara; Farre', Ramon

2017-06-01

This review addresses how the combination of physiology, medicine and engineering principles contributed to the development and advancement of mechanical ventilation, emphasising the most urgent needs for improvement and the most promising directions of future development. Several aspects of mechanical ventilation are introduced, highlighting on one side the importance of interdisciplinary research for further development and, on the other, the importance of training physicians sufficiently on the technological aspects of modern devices to exploit properly the great complexity and potentials of this treatment. To learn how mechanical ventilation developed in recent decades and to provide a better understanding of the actual technology and practice.To learn how and why interdisciplinary research and competences are necessary for providing the best ventilation treatment to patients.To understand which are the most relevant technical limitations in modern mechanical ventilators that can affect their performance in delivery of the treatment.To better understand and classify ventilation modes.To learn the classification, benefits, drawbacks and future perspectives of automatic ventilation tailoring algorithms.

46 CFR 42.15-45 - Ventilators.

Science.gov (United States)

2010-10-01

... 46 Shipping 2 2010-10-01 2010-10-01 false Ventilators. 42.15-45 Section 42.15-45 Shipping COAST... Conditions of Assignment of Freeboard § 42.15-45 Ventilators. (a) Ventilators in position 1 or 2 to spaces... any ventilator exceeds 351/2 inches in height it shall be specially supported. (b) Ventilators passing...

A comparison of leak compensation in acute care ventilators during noninvasive and invasive ventilation: a lung model study.

Science.gov (United States)

Oto, Jun; Chenelle, Christopher T; Marchese, Andrew D; Kacmarek, Robert M

2013-12-01

Although leak compensation has been widely introduced to acute care ventilators to improve patient-ventilator synchronization in the presence of system leaks, there are no data on these ventilators' ability to prevent triggering and cycling asynchrony. The goal of this study was to evaluate the ability of leak compensation in acute care ventilators during invasive and noninvasive ventilation (NIV). Using a lung simulator, the impact of system leaks was compared on 7 ICU ventilators and 1 dedicated NIV ventilator during triggering and cycling at 2 respiratory mechanics (COPD and ARDS models) settings, various modes of ventilation (NIV mode [pressure support ventilation], and invasive mode [pressure support and continuous mandatory ventilation]), and 2 PEEP levels (5 and 10 cm H(2)O). Leak levels used were up to 35-36 L/min in NIV mode and 26-27 L/min in invasive mode. Although all of the ventilators were able to synchronize with the simulator at baseline, only 4 of the 8 ventilators synchronized to all leaks in NIV mode, and 2 of the 8 ventilators in invasive mode. The number of breaths to synchronization was higher during increasing than during decreasing leak. In the COPD model, miss-triggering occurred more frequently and required a longer time to stabilize tidal volume than in the ARDS model. The PB840 required fewer breaths to synchronize in both invasive and noninvasive modes, compared with the other ventilators (P ventilators. The PB840 and the V60 were the only ventilators to acclimate to all leaks, but there were differences in performance between these 2 ventilators. It is not clear if these differences have clinical importance.

Pulmonary perfusion ''without ventilation''

International Nuclear Information System (INIS)

Chapman, C.N.; Sziklas, J.J.; Spencer, R.P.; Rosenberg, R.J.

1983-01-01

An 88-yr-old man, with prior left upper lobectomy and phrenic nerve injury, had a ventilation/perfusion lung image. Both wash-in and equilibrium ventilation images showed no radioactive gas in the left lung. Nevertheless, the left lung was perfused. A similar result was obtained on a repeat study 8 days later. Delayed images, during washout, showed some radioactive gas in the left lung. Nearly absent ventilation (but continued perfusion) of that lung might have been related to altered gas dynamics brought about by the prior lobectomy, a submucosal bronchial lesion, phrenic nerve damage, and limited motion of the left part of the diaphragm. This case raises the issue of the degree of ventilation (and the phase relationship between the lungs) required for the entry of radioactive gas into a diseased lung, and the production of a ''reversed ventilation/perfusion mismatch.''

Ventilation in Sewers Quantified by Measurements of CO2

DEFF Research Database (Denmark)

Fuglsang, Emil Dietz; Vollertsen, Jes; Nielsen, Asbjørn Haaning

2012-01-01

Understanding and quantifying ventilation in sewer systems is a prerequisite to predict transport of odorous and corrosive gasses within the system as well as their interaction with the urban atmosphere. This paper studies ventilation in sewer systems quantified by measurements of the natural...... occurring compound CO2. Most often Danish wastewater is supersaturated with CO2 and hence a potential for stripping is present. A novel model was built based on the kinetics behind the stripping process. It was applied to simulate ventilation rates from field measurements of wastewater temperature, p...

On analysis of operating efficiency of autonomous ventilation systems

Directory of Open Access Journals (Sweden)

Kostuganov Arman

2017-01-01

Full Text Available The paper deals with the causes and consequences of malfunctioning of natural and mechanical ventilation systems in civil buildings of Russia. Furthermore it gives their classification and analysis based on the literature review. On the basis of the analysis technical solutions for improving the efficiency of ventilation systems in civil buildings are summarized and the field of their application is specified. Among the offered technical solutions the use of autonomous ventilation systems with heat recovery is highlighted as one of the most promising and understudied. Besides it has a wide range of applications. The paper reviews and analyzes the main Russian and foreign designs of ventilation systems with heat recovery that are mostly used in practice. Three types of such systems: UVRK-50, Prana-150, ТеFо are chosen for consideration. The sequence of field tests of selected autonomous ventilation systems have been carried out in order to determine the actual air exchange and efficiency of heat recovery. The paper presents the processed results of the research on the basis of which advantages and disadvantages of the tested ventilation systems are identified and recommendations for engineering and manufacturing of new design models of autonomous ventilation systems with heat recovery are formulated.

High-Frequency Percussive Ventilation Revisited

Science.gov (United States)

2010-01-01

be implemented. ‡ Follow the reverse of the ventilation sequence if respiratory alkalosis develops—however, start at ventilation goal sequence 1 not at...High-frequency percussive ventilation (HFPV) has demonstrated a potential role as a rescue option for refractory acute respiratory distress syndrome...frequency percussive ventilation (HFPV) has demon- strated a potential role as a salvage option for refrac- tory acute respiratory distress syndrome

Plane Stratified Flow in a Room Ventilated by Displacement Ventilation

DEFF Research Database (Denmark)

Nielsen, Peter Vilhelm; Nickel, J.; Baron, D. J. G.

2004-01-01

The air movement in the occupied zone of a room ventilated by displacement ventilation exists as a stratified flow along the floor. This flow can be radial or plane according to the number of wall-mounted diffusers and the room geometry. The paper addresses the situations where plane flow...

The effect of helium on ventilator performance: study of five ventilators and a bedside Pitot tube spirometer.

Science.gov (United States)

Oppenheim-Eden, A; Cohen, Y; Weissman, C; Pizov, R

2001-08-01

To assess in vitro the performance of five mechanical ventilators-Siemens 300 and 900C (Siemens-Elma; Solna, Sweden), Puritan Bennett 7200 (Nellcor Puritan Bennett; Pleasanton, CA), Evita 4 (Dragerwerk; Lubeck, Germany), and Bear 1000 (Bear Medical Systems; Riverside CA)-and a bedside sidestream spirometer (Datex CS3 Respiratory Module; Datex-Ohmeda; Helsinki, Finland) during ventilation with helium-oxygen mixtures. In vitro study. ICUs of two university-affiliated hospitals. Each ventilator was connected to 100% helium through compressed air inlets and then tested at three to six different tidal volume (VT) settings using various helium-oxygen concentrations (fraction of inspired oxygen [FIO(2)] of 0.2 to 1.0). FIO(2) and VT were measured with the Datex CS3 spirometer, and VT was validated with a water-displacement spirometer. The Puritan Bennett 7200 ventilator did not function with helium. With the other four ventilators, delivered FIO(2) was lower than the set FIO(2). For the Siemens 300 and 900C ventilators, this difference could be explained by the lack of 21% oxygen when helium was connected to the air supply port, while for the other two ventilators, a nonlinear relation was found. The VT of the Siemens 300 ventilator was independent of helium concentration, while for the other three ventilators, delivered VT was greater than the set VT and was dependent on helium concentration. During ventilation with 80% helium and 20% oxygen, VT increased to 125% of set VT for the Siemens 900C ventilator, and more than doubled for the Evita 4 and Bear 1000 ventilators. Under the same conditions, the Datex CS3 spirometer underestimated the delivered VT by about 33%. At present, no mechanical ventilator is calibrated for use with helium. This investigation offers correction factors for four ventilators for ventilation with helium.

[A comparison of leak compensation in six acute care ventilators during non-invasive ventilation].

Science.gov (United States)

Hu, X S; Wang, Y; Wang, Z T; Yan, P; Zhang, X G; Zhao, S F; Xie, F; Gu, H J; Xie, L X

2017-02-12

Objective: To compare the ability of leak compensation in 6 medical ventilators during non-invasive ventilation. Methods: Six medical ventilators were selected, including 3 non-invasive ventilators (V60, Flexo and Stellar150), and 3 invasive ventilators(Avea, Servo I and BellaVist). Using a lung simulator, the ability of leak compensation was evaluated during triggering and cycling in 2 respiratory mechanics conditions (high airway resistance condition and high elastance resistance condition), and each condition was performed under 2 PEEP levels (4, and 8 cmH(2)O, 1 mmHg=0.098 kPa) at 4 air leak level conditions (L0: 2-3 L/min, L1: 8-10 L/min, L2: 22-27 L/min, L3: 35-40 L/min). Results: In the high elastance resistance condition (L2, L3)with different leak levels, the number of auto-triggering and miss-triggering of the non-invasive ventilator Flexo was significantly less than those of the others (L2: 1, 1; L3: 1.67, 1.33, P ventilators ( P ventilators (1, 0.67, 0, P ventilators in both high airway resistance and high elastance resistance conditions with L0 and L1 leak levels and PEEP levels [ARDS, PEEP=4: (109.8±1.8) ms, (112.0±0.6) ms; ARDS, PEEP=8: (103.1±0.7) ms, (109.7±0.7) ms; COPD, PEEP=4: (207.3±1.1) ms, (220.8±1.1) ms; COPD, PEEP=8: (195.6±6.7) ms, (200.0±1.2) ms , P ventilators could be synchronized, among which V60, Stellar150 and Flexo presented a good performance features in specific conditions.

Ventilation of nuclear power plants

International Nuclear Information System (INIS)

Madoyan, A.A.; Vlasik, V.F.

1984-01-01

Foundations and calculation methods of ventilation of rooms with different degree of heat and gas release with the change of operation mode of NPP main equipment, as well as problems of NPP site and adjoining area aerodynamics, have been presented. Systems of air ventilation and conditioning, cooling equipment, are considered. The main points of designing are described and determination of economic efficiency of the ventilation systems are made. Technical characteristics of the ventilators, conditioners, filters and air heaters used, are presented. Organization of adjustment, tests, operation and maintenance of the ventilation systems of NPP with RBMK and WWER-type reactors, is described

Position paper -- Tank ventilation system design air flow rates

International Nuclear Information System (INIS)

Goolsby, G.K.

1995-01-01

The purpose of this paper is to document a project position on required ventilation system design air flow rates for the waste storage tanks currently being designed by project W-236A, the Multi-Function Waste Tank Facility (MWTF). The Title 1 design primary tank heat removal system consists of two systems: a primary tank vapor space ventilation system; and an annulus ventilation system. At the conclusion of Title 1 design, air flow rates for the primary and annulus ventilation systems were 960 scfm and 4,400 scfm, respectively, per tank. These design flow rates were capable of removing 1,250,000 Btu/hr from each tank. However, recently completed and ongoing studies have resulted in a design change to reduce the extreme case heat load to 700,000 Btu/hr. This revision of the extreme case heat load, coupled with results of scale model evaporative testing performed by WHC Thermal Hydraulics, allow for a reduction of the design air flow rates for both primary and annulus ventilation systems. Based on the preceding discussion, ICF Kaiser Hanford Co. concludes that the design should incorporate the following design air flow rates: Primary ventilation system--500 scfm maximum and Annulus ventilation system--1,100 scfm maximum. In addition, the minimum air flow rates in the primary and annulus ventilation systems will be investigated during Title 2 design. The results of the Title 2 investigation will determine the range of available temperature control using variable air flows to both ventilation systems

Tunnel Ventilation Control Using Reinforcement Learning Methodology

Science.gov (United States)

Chu, Baeksuk; Kim, Dongnam; Hong, Daehie; Park, Jooyoung; Chung, Jin Taek; Kim, Tae-Hyung

The main purpose of tunnel ventilation system is to maintain CO pollutant concentration and VI (visibility index) under an adequate level to provide drivers with comfortable and safe driving environment. Moreover, it is necessary to minimize power consumption used to operate ventilation system. To achieve the objectives, the control algorithm used in this research is reinforcement learning (RL) method. RL is a goal-directed learning of a mapping from situations to actions without relying on exemplary supervision or complete models of the environment. The goal of RL is to maximize a reward which is an evaluative feedback from the environment. In the process of constructing the reward of the tunnel ventilation system, two objectives listed above are included, that is, maintaining an adequate level of pollutants and minimizing power consumption. RL algorithm based on actor-critic architecture and gradient-following algorithm is adopted to the tunnel ventilation system. The simulations results performed with real data collected from existing tunnel ventilation system and real experimental verification are provided in this paper. It is confirmed that with the suggested controller, the pollutant level inside the tunnel was well maintained under allowable limit and the performance of energy consumption was improved compared to conventional control scheme.

Passive Smoking in a Displacement Ventilated Room

DEFF Research Database (Denmark)

Bjørn, Erik; Nielsen, Peter V.

The aim of this research is to see if the displacement ventilation principle can protect a person from exposure to passive tobacco smoking. This is done by full-scale experiments with two breathing thermal manikins, smoke visualisations, and tracer gas measurements. In some situations, exhaled...... smoke will stratify in a certain height due to the vertical temperature gradient. This horizontal layer of exhaled tobacco smoke may lead to exposure. In other situations, the smoke is mixed into the upper zone, and the passive smoker is protected to some extent by the displacement principle...

Partial liquid ventilation improves lung function in ventilation-induced lung injury

NARCIS (Netherlands)

G.F. Vazquez de Anda; R.A. Lachmann; S.J.C. Verbrugge (Serge); D.A.M.P.J. Gommers (Diederik); J.J. Haitsma (Jack); B.F. Lachmann (Burkhard)

2001-01-01

textabstractDisturbances in lung function and lung mechanics are present after ventilation with high peak inspiratory pressures (PIP) and low levels of positive end-expiratory pressure (PEEP). Therefore, the authors investigated whether partial liquid ventilation can re-establish

Low resource ventilation unit; Ressourcebesparende ventilationsenhed

Energy Technology Data Exchange (ETDEWEB)

Drivsholm, C.

2012-03-15

In the project a resource-saving ventilation device was developed which is based on the use of a regenerator and a reversible air flow. The regenerator is placed in the building envelope, and the concept works in the way that the heat in the air during ventilation is stored in the regenerator and brought back into the building by a reversible air change. The heated air is blown from inside the building out through the regenerator. In this way the regenerator accumulates the heat in the air. Over a period of 30-120 seconds, the regenerator capacity is utilized. When the regenerator cannot be further heated, the air flow is reversed and there is now blown cold air through the regenerator. Thereby the heat from the regenerator is released to the cold fresh air. Thus, the fresh air brings heat back into the building, whereby the air is replaced with a limited heat loss. Ventilation with a regenerator is described as micro-ventilation. The developed micro-ventilation unit was tested by the Danish Technological Institute. The test results shows that the unit performs according to expectations: 1) The heat recovery is 85%; 2) The flow through the unit is 80m3 per hour in a 5 section unit; 3) The noise level is 30 db(A) in a representative room; 4) The energy consumption is <300 J/m3. The unit is introduced into the market, and the first plants have been sold. (LN)

TU-G-BRA-04: Changes in Regional Lung Function Measured by 4D-CT Ventilation Imaging for Thoracic Radiotherapy

International Nuclear Information System (INIS)

Nakajima, Y; Kadoya, N; Kabus, S; Loo, B; Keall, P; Yamamoto, T

2015-01-01

Purpose: To test the hypothesis: 4D-CT ventilation imaging can show the known effects of radiotherapy on lung function: (1) radiation-induced ventilation reductions, and (2) ventilation increases caused by tumor regression. Methods: Repeat 4D-CT scans (pre-, mid- and/or post-treatment) were acquired prospectively for 11 thoracic cancer patients in an IRB-approved clinical trial. A ventilation image for each time point was created using deformable image registration and the Hounsfield unit (HU)-based or Jacobian-based metric. The 11 patients were divided into two subgroups based on tumor volume reduction using a threshold of 5 cm 3 . To quantify radiation-induced ventilation reduction, six patients who showed a small tumor volume reduction (<5 cm 3 ) were analyzed for dose-response relationships. To investigate ventilation increase caused by tumor regression, two of the other five patients were analyzed to compare ventilation changes in the lung lobes affected and unaffected by the tumor. The remaining three patients were excluded because there were no unaffected lobes. Results: Dose-dependent reductions of HU-based ventilation were observed in a majority of the patient-specific dose-response curves and in the population-based dose-response curve, whereas no clear relationship was seen for Jacobian-based ventilation. The post-treatment population-based dose-response curve of HU-based ventilation demonstrated the average ventilation reductions of 20.9±7.0% at 35–40 Gy (equivalent dose in 2-Gy fractions, EQD2), and 40.6±22.9% at 75–80 Gy EQD2. Remarkable ventilation increases in the affected lobes were observed for the two patients who showed an average tumor volume reduction of 37.1 cm 3 and re-opening airways. The mid-treatment increase in HU-based ventilation of patient 3 was 100.4% in the affected lobes, which was considerably greater than 7.8% in the unaffected lobes. Conclusion: This study has demonstrated that 4D-CT ventilation imaging shows the known

Calibration of Mine Ventilation Network Models Using the Non-Linear Optimization Algorithm

Directory of Open Access Journals (Sweden)

Guang Xu

2017-12-01

Full Text Available Effective ventilation planning is vital to underground mining. To ensure stable operation of the ventilation system and to avoid airflow disorder, mine ventilation network (MVN models have been widely used in simulating and optimizing the mine ventilation system. However, one of the challenges for MVN model simulation is that the simulated airflow distribution results do not match the measured data. To solve this problem, a simple and effective calibration method is proposed based on the non-linear optimization algorithm. The calibrated model not only makes simulated airflow distribution results in accordance with the on-site measured data, but also controls the errors of other parameters within a minimum range. The proposed method was then applied to calibrate an MVN model in a real case, which is built based on ventilation survey results and Ventsim software. Finally, airflow simulation experiments are carried out respectively using data before and after calibration, whose results were compared and analyzed. This showed that the simulated airflows in the calibrated model agreed much better to the ventilation survey data, which verifies the effectiveness of calibrating method.

Passive cooling of buildings by night-time ventilation - Final report

Energy Technology Data Exchange (ETDEWEB)

Artmann, N.; Manz, H. [Swiss Federal Laboratories for Materials Testing and Research (EMPA), Duebendorf (Switzerland); Heiselberg, P. [Aalborg University, Aalborg (Denmark)

2008-07-01

Due to an overall trend towards an increasing cooling energy demand in buildings in many European countries over the last few decades, passive cooling by night-time ventilation is seen as a promising concept. However, because of uncertainties in thermal comfort predictions, architects and engineers are still hesitant to apply passive cooling techniques. As night-time ventilation is highly dependent on climatic conditions, a method for quantifying the climatic cooling potential was developed and the impact of climate warming was investigated. Although a clear temperature decrease was found, significant potential will remain, especially if night-time ventilation is applied in combination with other cooling methods. Building energy simulations showed that the performance of night-time ventilation is also affected by the heat transfer at internal room surfaces, as the cooling effect is very limited due to heat transfer coefficients below about 4 W/m{sup 2}K. Heat transfer during night-time ventilation in case of mixing and displacement ventilation was investigated in a full scale test room at Aalborg University. In the experiments the temperature efficiency of the ventilation was determined. Based on the previous results a method for estimating the potential for cooling by night-time ventilation at an early stage of design was developed. (author)

Design Principles for Natural and Hybrid Ventilation

DEFF Research Database (Denmark)

Heiselberg, Per

For many years mechanical and natural ventilation systems have developed separately. Naturally, the next step in this development is the development of ventilation concepts that utilize and combine the best features from each system to create a new type of ventilation system- Hybrid Ventilation. ....... The hybrid ventilation concepts, design challenges and principles are discussed and illustrated by four building examples.......For many years mechanical and natural ventilation systems have developed separately. Naturally, the next step in this development is the development of ventilation concepts that utilize and combine the best features from each system to create a new type of ventilation system- Hybrid Ventilation...

Temperature of gas delivered from ventilators.

Science.gov (United States)

Chikata, Yusuke; Onodera, Mutsuo; Imanaka, Hideaki; Nishimura, Masaji

2013-01-01

Although heated humidifiers (HHs) are the most efficient humidifying device for mechanical ventilation, some HHs do not provide sufficient humidification when the inlet temperature to the water chamber is high. Because portable and home-care ventilators use turbines, blowers, pistons, or compressors to inhale in ambient air, they may have higher gas temperature than ventilators with piping systems. We carried out a bench study to investigate the temperature of gas delivered from portable and home-care ventilators, including the effects of distance from ventilator outlet, fraction of inspiratory oxygen (FIO2), and minute volume (MV). We evaluated five ventilators equipped with turbine, blower, piston, or compressor system. Ambient air temperature was adjusted to 24°C ± 0.5°C, and ventilation was set at FIO2 0.21, 0.6, and 1.0, at MV 5 and 10 L/min. We analyzed gas temperature at 0, 40, 80, and 120 cm from ventilator outlet and altered ventilator settings. While temperature varied according to ventilators, the outlet gas temperature of ventilators became stable after, at the most, 5 h. Gas temperature was 34.3°C ± 3.9°C at the ventilator outlet, 29.5°C ± 2.2°C after 40 cm, 25.4°C ± 1.2°C after 80 cm and 25.1°C ± 1.2°C after 120 cm (P < 0.01). FIO2 and MV did not affect gas temperature. Gas delivered from portable and home-care ventilator was not too hot to induce heated humidifier malfunctioning. Gas soon declined when passing through the limb.

Pretest Predictions for Ventilation Tests

International Nuclear Information System (INIS)

Y. Sun; H. Yang; H.N. Kalia

2007-01-01

The objective of this calculation is to predict the temperatures of the ventilating air, waste package surface, concrete pipe walls, and insulation that will be developed during the ventilation tests involving various test conditions. The results will be used as input to the following three areas: (1) Decisions regarding testing set-up and performance. (2) Assessing how best to scale the test phenomena measured. (3) Validating numerical approach for modeling continuous ventilation. The scope of the calculation is to identify the physical mechanisms and parameters related to thermal response in the ventilation tests, and develop and describe numerical methods that can be used to calculate the effects of continuous ventilation. Sensitivity studies to assess the impact of variation of linear power densities (linear heat loads) and ventilation air flow rates are included. The calculation is limited to thermal effect only

Diffuse Ceiling Ventilation

DEFF Research Database (Denmark)

Zhang, Chen; Heiselberg, Per; Nielsen, Peter V.

2014-01-01

As a novel air distribution system, diffuse ceiling ventilation combines the suspended acoustic ceiling with ventilation supply. Due to the low-impulse supply from the large ceiling area, the system does not generate draught when supplying cold air. However, heat sources play an important role...

Short-term airing by natural ventilation

DEFF Research Database (Denmark)

Perino, Marco; Heiselberg, Per

2009-01-01

The need to improve the energy efficiency of buildings requires new and more efficient ventilation systems. It has been demonstrated that innovative operating concepts that make use of natural ventilation seem to be more appreciated by occupants. This kind of system frequently integrates traditio......The need to improve the energy efficiency of buildings requires new and more efficient ventilation systems. It has been demonstrated that innovative operating concepts that make use of natural ventilation seem to be more appreciated by occupants. This kind of system frequently integrates...... traditional mechanical ventilation components with natural ventilation devices, such as motorized windows and louvers. Among the various ventilation strategies that are currently available, buoyancy driven single-sided natural ventilation has proved to be very effective and can provide high air change rates...... that was aimed at developing and validating numerical models for the analysis of buoyancy driven single-sided natural ventilation systems. Once validated, these models can be used to optimize control strategies in order to achieve satisfactory indoor comfort conditions and IAQ....

Demand controlled ventilation; Behovsstyrt ventilasjon

Energy Technology Data Exchange (ETDEWEB)

Soerensen, Henning Holm

2006-07-01

The terms CAV and VAV have been known terms for many years in the ventilation business. The terms are also included in building regulations, but the time is now right to focus on demand controlled ventilation (DCV). The new building regulations and the accompanying energy framework underline the need for a more nuanced thinking when it comes to controlling ventilation systems. Descriptions and further details of the ventilation systems are provided (ml)

Performance potential of mechanical ventilation systems with minimized pressure loss

DEFF Research Database (Denmark)

Terkildsen, Søren; Svendsen, Svend

2013-01-01

simulations that quantify fan power consumption, heating demand and indoor environmental conditions. The system was designed with minimal pressure loss in the duct system and heat exchanger. Also, it uses state-of-the-art components such as electrostatic precipitators, diffuse ceiling inlets and demand......In many locations mechanical ventilation has been the most widely used principle of ventilation over the last 50 years but the conventional system design must be revised to comply with future energy requirements. This paper examines the options and describes a concept for the design of mechanical...... ventilation systems with minimal pressure loss and minimal energy use. This can provide comfort ventilation and avoid overheating through increased ventilation and night cooling. Based on this concept, a test system was designed for a fictive office building and its performance was documented using building...

Advanced design of local ventilation systems

Energy Technology Data Exchange (ETDEWEB)

Kulmala, I. [VTT Manufacturing Technology, Espoo (Finland). Safety Technology

1997-12-31

Local ventilation is widely used in industry for controlling airborne contaminants. However, the present design practices of local ventilation systems are mainly based on empirical equations and do not take quantitatively into account the various factors affecting the performance of these systems. The aim of this study was to determine the applicability and limitations of more advanced fluid mechanical methods to the design and development of local ventilation systems. The most important factors affecting the performance of local ventilation systems were determined and their effect was studied in a systematic manner. The numerical calculations were made with the FLUENT computer code and they were verified by laboratory experiments, previous measurements or analytical solutions. The results proved that the numerical calculations can provide a realistic simulation of exhaust openings, effects of ambient air flows and wake regions. The experiences with the low-velocity local supply air showed that these systems can also be modelled fairly well. The results were used to improve the efficiency and thermal comfort of a local ventilation unit and to increase the effective control range of exhaust hoods. In the simulation of the interaction of a hot buoyant source and local exhaust, the predicted capture efficiencies were clearly higher than those observed experimentally. The deviations between measurements and non-isothermal flow calculations may have partly been caused by the inability to achieve grid independent solutions. CFD simulations is an advanced and flexible tool for designing and developing local ventilation. The simulations can provide insight into the time-averaged flow field which may assist us in understanding the observed phenomena and to explain experimental results. However, for successful calculations the applicability and limitations of the models must be known. (orig.) 78 refs.

Ventilator and viral induced inflammation

NARCIS (Netherlands)

Hennus, M.P.

2013-01-01

This thesis expands current knowledge on ventilator induced lung injury and provides insights on the immunological effects of mechanical ventilation during viral respiratory infections. The experimental studies in the first part of this thesis improve our understanding of how mechanical ventilation

Intelligent interaction based on holographic personalized portal

Directory of Open Access Journals (Sweden)

Yadong Huang

2017-06-01

Full Text Available Purpose – The purpose of this paper is to study the architecture of holographic personalized portal, user modeling, commodity modeling and intelligent interaction. Design/methodology/approach – In this paper, the authors propose crowd-science industrial ecological system based on holographic personalized portal and its interaction. The holographic personality portal is based on holographic enterprises, commodities and consumers, and the personalized portal consists of accurate ontology, reliable supply, intelligent demand and smart cyberspace. Findings – The personalized portal can realize the information acquisition, characteristic analysis and holographic presentation. Then, the intelligent interaction, e.g. demand decomposition, personalized search, personalized presentation and demand prediction, will be implemented within the personalized portal. Originality/value – The authors believe that their work on intelligent interaction based on holographic personalized portal, which has been first proposed in this paper, is innovation focusing on the interaction between intelligence and convenience.

Passive ventilation systems with heat recovery and night cooling

DEFF Research Database (Denmark)

Hviid, Christian Anker; Svendsen, Svend

2008-01-01

with little energy consumption and with satisfying indoor climate. The concept is based on using passive measures like stack and wind driven ventilation, effective night cooling and low pressure loss heat recovery using two fluid coupled water-to-air heat exchangers developed at the Technical University......In building design the requirements for energy consumption for ventilation, heating and cooling and the requirements for increasingly better indoor climate are two opposing factors. This paper presents the schematic layout and simulation results of an innovative multifunc-tional ventilation concept...... of Denmark. Through building integration in high performance offices the system is optimized to incorporate multiple functions like heating, cooling and ventilation, thus saving the expenses of separate cooling and heating systems. The simulation results are derived using the state-of-the-art building...

Demand controlled ventilation in a bathroom

DEFF Research Database (Denmark)

Mortensen, Dorthe Kragsig; Nielsen, Toke Rammer; Topp, Claus

2008-01-01

consumption during periods where the demand for ventilation is low and poor indoor climate during periods where the demand for ventilation is high. Controlling the ventilation rate by demand can improve the energy performance of the ventilation system and the indoor climate. This paper compares the indoor...... climate and energy consumption of a Constant Air Volume (CAV) system and a Demand Controlled Ventilation (DCV) system for two different bathroom designs. The air change rate of the CAV system corresponded to 0.5h-1. The ventilation rate of the DCV system was controlled by occupancy and by the relative...

Styret naturlig ventilation

DEFF Research Database (Denmark)

Morsing, S.; Strøm, J.S.

Publikationen præsenterer et generelt dimensioneringsgrundlag for naturlig ventilation i husdyrstalde. Det er kontrolleret ved forsøg i slagtesvinestalde, hvor det ligeledes er undersøgt hvilken temperaturstabilitet, der kan opnås ved naturlig ventilation, samt produktions- og adfærdsmæssige...

[Evaluation of tidal volume delivered by ventilators during volume-controlled ventilation].

Science.gov (United States)

Zhou, Juan; Yan, Yong; Cao, Desen

2014-12-01

To study the ways which ensure the delivery of enough tidal volume to patients under various conditions close to the demand of the physician. The volume control ventilation model was chosen, and the simulation lung type was active servo lung ASL 5000 or Michigan lung 1601. The air resistance, air compliance and lung type in simulation lungs were set. The tidal volume was obtained from flow analyzer PF 300. At the same tidal volume, the displaying values of tidal volume of E5, Servo i, Evital 4, and Evital XL ventilators with different lung types of patient, compliance of gas piping, leakage, gas types, etc. were evaluated. With the same setting tidal volume of a same ventilator, the tidal volume delivered to patients was different with different lung types of patient, compliance of gas piping, leakage, gas types, etc. Reducing compliance and increasing resistance of the patient lungs caused high peak airway pressure, the tidal volume was lost in gas piping, and the tidal volume be delivered to the patient lungs was decreased. If the ventilator did not compensate to leakage, the tidal volume delivered to the patient lungs was decreased. When the setting gas type of ventilator did not coincide with that applying to the patient, the tidal volume be delivered to the patient lungs might be different with the setting tidal volume of ventilator. To ensure the delivery of enough tidal volume to patients close to the demand of the physician, containable factors such as the compliance of gas piping, leakage, and gas types should be controlled.

Ventilator associated pneumonia among patients on mechanical ventilation at tertiary care centres

International Nuclear Information System (INIS)

Rafiq, M.Y.; Ikram, A.; Ayyub, M.

2018-01-01

Objective: To determine the frequency of ventilator associated pneumonia (VAP) among patients on mechanical ventilation, and to identify the causative bacterial pathogens and antibiotic susceptibility pattern of isolated microorganisms in intensive care units of tertiary care settings. Study Design: Descriptive cross sectional. Place and Duration of Study: This study was conducted at Microbiology Department, Armed Forces Institute of Pathology (AFIP), Rawalpindi, from Dec 2014 to Aug 2015. Material and Methods: A total of 176 patients on mechanical ventilation were included in the study; patients having respiratory tract infection before putting on ventilator were excluded. Endotracheal aspirate (ETA) and Bronchoalveolar lavage (BAL) samples were collected aseptically from patients on mechanical ventilation on day zero i.e. the day on which the patient was put on ventilator to rule out any previous respiratory tract infection and then after 48 hours to observe the development of VAP. Samples were processed in the laboratory by standard culture techniques, pathogens were identified and their antibiotic susceptibility was performed as per CLSI guidelines. Results: Out of 176 patients on mechanical ventilation, 59 (33.5%) developed VAP. Acinetobacter baumanii being the predominant pathogen isolated from 32 (54.2%) patients followed by MRSA 11 (18.6%), Klebsiella pneumoniae 9 (15.2%), Pseudomonas aeruginosa 5 (8.47%) and Stenotrophomonas maltophila from 2 (3.38%) patients. Conclusion: Frequency of VAP is quite high in our setup, identification of causative bacterial pathogensand their antibiotic susceptibility pattern will not only help in providing effective treatment to the patients but will also help in the formulation of antibiogram according to local resistance patterns for empirical therapy and to reduce the morbidity and mortality. (author)

A novel personal cooling system (PCS) incorporated with phase change materials (PCMs) and ventilation fans: An investigation on its cooling efficiency.

Science.gov (United States)

Lu, Yehu; Wei, Fanru; Lai, Dandan; Shi, Wen; Wang, Faming; Gao, Chuansi; Song, Guowen

2015-08-01

Personal cooling systems (PCS) have been developed to mitigate the impact of severe heat stress for humans working in hot environments. It is still a great challenge to develop PCSs that are portable, inexpensive, and effective. We studied the performance of a new hybrid PCS incorporating both ventilation fans and phase change materials (PCMs). The cooling efficiency of the newly developed PCS was investigated on a sweating manikin in two hot conditions: hot humid (HH, 34°C, 75% RH) and hot dry (HD, 34°C, 28% RH). Four test scenarios were selected: fans off with no PCMs (i.e., Fan-off, the CONTROL), fans on with no PCMs (i.e., Fan-on), fans off with fully solidified PCMs (i.e., PCM+Fan-off), and fans on with fully solidified PCMs (i.e., PCM+Fan-on). It was found that the addition of PCMs provided a 54∼78min cooling in HH condition. In contrast, the PCMs only offered a 19-39min cooling in HD condition. In both conditions, the ventilation fans greatly enhanced the evaporative heat loss compared with Fan-off. The hybrid PCS (i.e., PCM+Fan-on) provided a continuous cooling effect during the three-hour test and the average cooling rate for the whole body was around 111 and 315W in HH and HD conditions, respectively. Overall, the new hybrid PCS may be an effective means of ameliorating symptoms of heat stress in both hot-humid and hot-dry environments. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effect of flashlight guidance on manual ventilation performance in cardiopulmonary resuscitation: A randomized controlled simulation study.

Science.gov (United States)

Kim, Ji Hoon; Beom, Jin Ho; You, Je Sung; Cho, Junho; Min, In Kyung; Chung, Hyun Soo

2018-01-01

Several auditory-based feedback devices have been developed to improve the quality of ventilation performance during cardiopulmonary resuscitation (CPR), but their effectiveness has not been proven in actual CPR situations. In the present study, we investigated the effectiveness of visual flashlight guidance in maintaining high-quality ventilation performance. We conducted a simulation-based, randomized, parallel trial including 121 senior medical students. All participants were randomized to perform ventilation during 2 minutes of CPR with or without flashlight guidance. For each participant, we measured mean ventilation rate as a primary outcome and ventilation volume, inspiration velocity, and ventilation interval as secondary outcomes using a computerized device system. Mean ventilation rate did not significantly differ between flashlight guidance and control groups (P = 0.159), but participants in the flashlight guidance group exhibited significantly less variation in ventilation rate than participants in the control group (Pguidance group. Our results demonstrate that flashlight guidance is effective in maintaining a constant ventilation rate and interval. If confirmed by further studies in clinical practice, flashlight guidance could be expected to improve the quality of ventilation performed during CPR.

Neonatal and adult ICU ventilators to provide ventilation in neonates, infants, and children: a bench model study.

Science.gov (United States)

Vignaux, Laurence; Piquilloud, Lise; Tourneux, Pierre; Jolliet, Philippe; Rimensberger, Peter C

2014-10-01

Using a bench test model, we investigated the hypothesis that neonatal and/or adult ventilators equipped with neonatal/pediatric modes currently do not reliably administer pressure support (PS) in neonatal or pediatric patient groups in either the absence or presence of air leaks. PS was evaluated in 4 neonatal and 6 adult ventilators using a bench model to evaluate triggering, pressurization, and cycling in both the absence and presence of leaks. Delivered tidal volumes were also assessed. Three patients were simulated: a preterm infant (resistance 100 cm H2O/L/s, compliance 2 mL/cm H2O, inspiratory time of the patient [TI] 400 ms, inspiratory effort 1 and 2 cm H2O), a full-term infant (resistance 50 cm H2O/L/s, compliance 5 mL/cm H2O, TI 500 ms, inspiratory effort 2 and 4 cm H2O), and a child (resistance 30 cm H2O/L/s, compliance 10 mL/cm H2O, TI 600 ms, inspiratory effort 5 and 10 cm H2O). Two PS levels were tested (10 and 15 cm H2O) with and without leaks and with and without the leak compensation algorithm activated. Without leaks, only 2 neonatal ventilators and one adult ventilator had trigger delays under a given predefined acceptable limit (1/8 TI). Pressurization showed high variability between ventilators. Most ventilators showed TI in excess high enough to seriously impair patient-ventilator synchronization (> 50% of the TI of the subject). In some ventilators, leaks led to autotriggering and impairment of ventilation performance, but the influence of leaks was generally lower in neonatal ventilators. When a noninvasive ventilation algorithm was available, this was partially corrected. In general, tidal volume was calculated too low by the ventilators in the presence of leaks; the noninvasive ventilation algorithm was able to correct this difference in only 2 adult ventilators. No ventilator performed equally well under all tested conditions for all explored parameters. However, neonatal ventilators tended to perform better in the presence of leaks

WE-AB-BRA-06: 4DCT-Ventilation: A Novel Imaging Modality for Thoracic Surgical Evaluation

International Nuclear Information System (INIS)

Vinogradskiy, Y; Jackson, M; Schubert, L; Jones, B; Mitchell, J; Kavanagh, B; Miften, M; Castillo, R; Castillo, E; Guerrero, T

2016-01-01

Purpose: The current standard-of-care imaging used to evaluate lung cancer patients for surgical resection is nuclear-medicine ventilation. Surgeons use nuclear-medicine images along with pulmonary function tests (PFT) to calculate percent predicted postoperative (%PPO) PFT values by estimating the amount of functioning lung that would be lost with surgery. 4DCT-ventilation is an emerging imaging modality developed in radiation oncology that uses 4DCT data to calculate lung ventilation maps. We perform the first retrospective study to assess the use of 4DCT-ventilation for pre-operative surgical evaluation. The purpose of this work was to compare %PPO-PFT values calculated with 4DCT-ventilation and nuclear-medicine imaging. Methods: 16 lung cancer patients retrospectively reviewed had undergone 4DCTs, nuclear-medicine imaging, and had Forced Expiratory Volume in 1 second (FEV1) acquired as part of a standard PFT. For each patient, 4DCT data sets, spatial registration, and a density-change based model were used to compute 4DCT-ventilation maps. Both 4DCT and nuclear-medicine images were used to calculate %PPO-FEV1 using %PPO-FEV1=pre-operative FEV1*(1-fraction of total ventilation of resected lung). Fraction of ventilation resected was calculated assuming lobectomy and pneumonectomy. The %PPO-FEV1 values were compared between the 4DCT-ventilation-based calculations and the nuclear-medicine-based calculations using correlation coefficients and average differences. Results: The correlation between %PPO-FEV1 values calculated with 4DCT-ventilation and nuclear-medicine were 0.81 (p<0.01) and 0.99 (p<0.01) for pneumonectomy and lobectomy respectively. The average difference between the 4DCT-ventilation based and the nuclear-medicine-based %PPO-FEV1 values were small, 4.1±8.5% and 2.9±3.0% for pneumonectomy and lobectomy respectively. Conclusion: The high correlation results provide a strong rationale for a clinical trial translating 4DCT-ventilation to the surgical

Hybrid Ventilation Air Flow Process

DEFF Research Database (Denmark)

Heiselberg, Per Kvols

The scope of this annex is therefore to obtain better knowledge of the use of hybrid ventilation technologies. The annex focus on development of control strategies for hybrid ventilation, on development of methods to predict hybrid ventilation performance in office buildings and on implementation...

Nuclear waste repository ventilation system studies

International Nuclear Information System (INIS)

Smith, P.R.; Hensel, E.C.; Leslie, I.H.; Schultheis, T.M.; Walls, J.R.; Gregory, W.S.

1993-01-01

Ventilation studies of the Waste Isolation Pilot Plant described in this article were performed by personnel from New Mexico State University in collaboration with Sandia National Laboratories, Los Alamos National Laboratory, and Westinghouse Corporation. The following research tasks were performed: 1) High-efficiency particulate air filters of the type used at the Waste Isolation Pilot Plant were loaded with salt aerosol from the site, 2) Filter resistance as a function of salt mass and flow rate was established for later use in computer simulations, 3) Filter efficiency was measured during the loading tests to establish a relation between efficiency and salt loading, 4) The structural strength of the salt-loaded high-efficiency filters was investigated by subjecting the filters to pressure transients of the types expected from fires, explosions and tornados, 5) Computer codes, obtained from Los Alamos National Laboratory, were used to model the ventilation systems and study their response to accident-induced pressure transients and heat fluxes, 6) Partial verification of the computer simulations was obtained by comparing normal operation of the ventilation systems to predicted normal operation, 7) A feasibility study using model-based control of the ventilation systems was initiated and will be completed during the second year of the project. (author) 12 figs., 16 refs

Equivalence in Ventilation and Indoor Air Quality

Energy Technology Data Exchange (ETDEWEB)

Sherman, Max; Walker, Iain; Logue, Jennifer

2011-08-01

We ventilate buildings to provide acceptable indoor air quality (IAQ). Ventilation standards (such as American Society of Heating, Refrigerating, and Air-Conditioning Enginners [ASHRAE] Standard 62) specify minimum ventilation rates without taking into account the impact of those rates on IAQ. Innovative ventilation management is often a desirable element of reducing energy consumption or improving IAQ or comfort. Variable ventilation is one innovative strategy. To use variable ventilation in a way that meets standards, it is necessary to have a method for determining equivalence in terms of either ventilation or indoor air quality. This study develops methods to calculate either equivalent ventilation or equivalent IAQ. We demonstrate that equivalent ventilation can be used as the basis for dynamic ventilation control, reducing peak load and infiltration of outdoor contaminants. We also show that equivalent IAQ could allow some contaminants to exceed current standards if other contaminants are more stringently controlled.

Operational experience of air washer based ventilation system for power conditioning system of Indus-2

International Nuclear Information System (INIS)

Pandey, R.M.; Baghel, S.L.; Parate, J.K.; Ahlawat, Sandeep; Rawlani, B.K.; Chouksey, Sanjay

2015-01-01

Indus-2 Synchrotron Accelerator requires high quality conditioned uninterrupted AC mains power for their smooth and reliable operation. Three units of 1670 kVA and one unit of 1100 kVA capacity rotary uninterruptible power conditioning systems (UPS) were installed and commissioned. These UPS units require dust free and cool ambient conditions for smooth operation. In order to meet the ventilation requirements, an evaporative cooling system of 80000 cubic meter/hour capacity with filtration units was designed, installed and commissioned in February 2011 and is operational on round-the-clock basis. Evaporative cooling scheme was chosen as has various advantages over a refrigerated system like lower initial capital costs, lower energy usage, lower running costs, less greenhouse gas and it does not contribute to ozone depletion. The ventilation system filters the environment air in stages up to 5 micron level and being conditioned with an automatic controlled soft water circulating system with cooling pads. An instrumentation and control scheme is included in the system to provide the automation requirements for operating 24 x 7 through the year. All the mechanical, hydraulic and electrical devices are maintained by providing preventive maintenance work without affecting the accelerator machine operation. Availability and reliability of the system was analysed based on the failure data. In Year 2014, the ventilation system was upgraded to accommodate standby blower unit, coupling unit and improved quality of supply air with new air conditioning devices. The control panel monitors the condition of air in the UPS hall and maintainsup to 28°C air temperature and 85% maximum relative humidity in round-the clock shift with more than 98% operational reliability. In this paper, we present design philosophy, installation, instrumentation, testing, operation experience and availability of the ventilation system for Power Conditioning System, Indus complex. (author)

Mechanical ventilation in patients subjected to extracorporeal membrane oxygenation (ECMO).

Science.gov (United States)

López Sanchez, M

2017-11-01

Mechanical ventilation (MV) is a crucial element in the management of acute respiratory distress syndrome (ARDS), because there is high level evidence that a low tidal volume of 6ml/kg (protective ventilation) improves survival. In these patients with refractory respiratory insufficiency, venovenous extracorporeal membrane oxygenation (ECMO) can be used. This salvage technique improves oxygenation, promotes CO 2 clearance, and facilitates protective and ultraprotective MV, potentially minimizing ventilation-induced lung injury. Although numerous trials have investigated different ventilation strategies in patients with ARDS, consensus is lacking on the optimal MV settings during venovenous ECMO. Although the concept of "lung rest" was introduced years ago, there are no evidence-based guidelines on its use in application to MV in patients supported by ECMO. How MV in ECMO patients can promote lung recovery and weaning from ventilation is not clear. The purpose of this review is to describe the ventilation strategies used during venovenous ECMO in clinical practice. Copyright © 2017 Elsevier España, S.L.U. y SEMICYUC. All rights reserved.

Correlation between alveolar ventilation and electrical properties of lung parenchyma.

Science.gov (United States)

Roth, Christian J; Ehrl, Andreas; Becher, Tobias; Frerichs, Inéz; Schittny, Johannes C; Weiler, Norbert; Wall, Wolfgang A

2015-06-01

One key problem in modern medical imaging is linking measured data and actual physiological quantities. In this article we derive such a link between the electrical bioimpedance of lung parenchyma, which can be measured by electrical impedance tomography (EIT), and the magnitude of regional ventilation, a key to understanding lung mechanics and developing novel protective ventilation strategies. Two rat-derived three-dimensional alveolar microstructures obtained from synchrotron-based x-ray tomography are each exposed to a constant potential difference for different states of ventilation in a finite element simulation. While the alveolar wall volume remains constant during stretch, the enclosed air volume varies, similar to the lung volume during ventilation. The enclosed air, serving as insulator in the alveolar ensemble, determines the resulting current and accordingly local tissue bioimpedance. From this we can derive a relationship between lung tissue bioimpedance and regional alveolar ventilation. The derived relationship shows a linear dependence between air content and tissue impedance and matches clinical data determined from a ventilated patient at the bedside.

21 CFR 868.5975 - Ventilator tubing.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Ventilator tubing. 868.5975 Section 868.5975 Food... DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5975 Ventilator tubing. (a) Identification. Ventilator tubing is a device intended for use as a conduit for gases between a ventilator and a patient...

Ventilating Air-Conditioner

Science.gov (United States)

Dinh, Khanh

1994-01-01

Air-conditioner provides ventilation designed to be used alone or incorporated into cooling or heating system operates efficiently only by recirculating stale air within building. Energy needed to operate overall ventilating cooling or heating system slightly greater than operating nonventilating cooling or heating system. Helps to preserve energy efficiency while satisfying need for increased forced ventilation to prevent accumulation of undesired gases like radon and formaldehyde. Provides fresh treated air to variety of confined spaces: hospital surgeries, laboratories, clean rooms, and printing shops and other places where solvents used. In mobile homes and portable classrooms, eliminates irritant chemicals exuded by carpets, panels, and other materials, ensuring healthy indoor environment for occupants.

Influence of ventilation strategies on indoor radon concentrations based on a semiempirical model for Florida-style houses

International Nuclear Information System (INIS)

Hintenlang, D.E.; Al-Ahmady, K.K.

1994-01-01

Measurements in a full-scale experimental facility are used to benchmark a semiempirical model for predicting indoor radon concentrations for Florida-style houses built using slab-on-grade construction. The model is developed to provide time-averaged indoor radon concentrations from quantitative relationships between the time-dependent radon entry and elimination mechanisms that have been demonstrated to be important for this style of residential construction. The model successfully predicts indoor radon concentrations in the research structure for several pressure and ventilation conditions. Parametric studies using the model illustrate how different ventilation strategies affect indoor radon concentrations. It is demonstrated that increasing house ventilation rates by increasing the effective leakage area of the house shell does not reduce indoor radon concentrations as effectively as increasing house ventilation rates by controlled duct ventilation associated with the heating, ventilating, and air conditioning system. The latter strategy provides the potential to minimize indoor radon concentrations while providing positive control over the quality of infiltration air. 9 refs., 5 figs

The role of ventilation. 2 v. Proceedings

International Nuclear Information System (INIS)

1994-01-01

The 78 papers which constitute the proceedings of the conference are presented in two volumes. The papers in the first volume cover sessions dealing with the following broad topics: ventilation strategies; indoor air quality; energy impact of ventilation; building design for optimum ventilation; ventilation and energy. Volume 2 also covers ventilation strategies and ventilation and energy, and in addition: calculation, measurement and design tools; measurement and modelling. Separate abstract have been prepared for 4 papers in Volume 1 which deal with the role of ventilation in mitigating the hazard of radon in buildings. (UK)

Optimized damper control of pressure and airflow in ventilation systems

DEFF Research Database (Denmark)

Koulani, Chrysanthi Sofia; Hviid, Christian Anker; Terkildsen, Søren

2014-01-01

Conventional control strategies in variable air volume (VAV) ventilation systems do not take fully into advantage the potential energy savings since the system operation is based on maintaining a constant static pressure (CSP) set point in the main duct irrespective of the actual pressure demand...... by using the Simulink programming tool which is addon software to MATLAB mathematical programming language. A model of a VAV ventilation system was created in Simulink based on the International Building Physics Toolbox (IBPT); the IBPT thermal zone was remodelled in order to calculate dynamically...... the airflow demand according to the zone air temperature. The performance of the Simulink model was evaluated based on the experimental setup of the ventilation system. The SPR control method established stable system operation and was proven efficient to maintain comfortable space conditions while reducing...

[Alveolar ventilation and recruitment under lung protective ventilation].

Science.gov (United States)

Putensen, Christian; Muders, Thomas; Kreyer, Stefan; Wrigge, Hermann

2008-11-01

Goal of mechanical ventilation is to improve gas exchange and reduce work of breathing without contributing to further lung injury. Besides providing adequate EELV and thereby arterial oxygenation PEEP in addition to a reduction in tidal volume is required to prevent cyclic alveolar collapse and tidal recruitment and hence protective mechanical ventilation. Currently, there is no consensus if and if yes at which price alveolar recruitment with high airway pressures should be intended ("open up the lung"), or if it is more important to reduce the mechanical stress and strain to the lungs as much as possible ("keep the lung closed"). Potential of alveolar recruitment differs from patient to patient but also between lung regions. Potential for recruitment depends probably more on regional lung mechanics - especially on lung elastance - than on the underlying disease. Based on available data neither high PEEP nor other methods used for alveolar recruitment could demonstrate a survival benefit in patients with ARDS. These results may support an individualized titration of PEEP or other manoeuvres used for recruitment taking into consideration the regional effects. Bedside imaging techniques allowing titration of PEEP or other manoeuvres to prevent end-expiratory alveolar collapse (tidal recruitment) and inspiratory overinflation may be a promising development.

Ventilation of radioactive enclosures; Ventilation des enceintes radioactives

Energy Technology Data Exchange (ETDEWEB)

Caminade, F; Laurent, H [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1957-07-01

Mechanical, physical and chemical manipulations on radioactive products must be carried out in properly ventilated enclosed places. The air extracted can only be discharged into the atmosphere after a correct filtration. The power of the ventilation systems is a function of the dimensions and purpose of the enclosure? The choice of types of filter is determined by the physical state and chemical nature of the radioactive materials to be manipulated. This study deals with the individual equipment of small installations: glove boxes, manipulation boxes with outside control and, if necessary, production chambers (maximum useful volume: 5 m{sup 3}). The performances of three types of 'ventilators', and the modifications provided by the addition of filters, are measured and compared. (author) [French] Les manipulations oceaniques, physiques et chimiques sur des produits radioactifs doivent s'effectuer dans des enceintes convenablement ventilees. L'air extrait ne peut etre rejete dans l'atmosphere qu'apres une filtration correcte. La puissance des installations de ventilation est fonction des dimensions de l'enceinte et de son utilisation. Le choix des types de filtres est determine par l'etat physique et la nature ehimique des corps radioactifs manipules. Notre etude porte sur l'equipement individuel d'installations de petites dimensions: boites a gants, boites a pinces et, a la rigueur, enceintes de production (volume maximum utilisable 5 m{sup 3}). Nous mesurons et comparons les performances de trois types de 'ventilateurs' et les modifications apportees par l'adjonction de filtres. (auteur)

A guide to ventilation requirements for uranium mines and mills. Regulatory guide G-221

International Nuclear Information System (INIS)

2003-06-01

The purpose of G-221 is to help persons address the requirements for the submission of ventilation-related information when applying for a Canadian Nuclear Safety Commission (CNSC) licence to site and construct, operate or decommission a uranium mine or mill. This guide is also intended to help applicants for a uranium mine or mill licence understand their operational and maintenance obligations with respect to ventilation systems, and to help CNSC staff evaluate the adequacy of applications for uranium mine and mill licences. This guide is relevant to any application for a CNSC licence to prepare a site for and construct, operate or decommission a uranium mine or mill. In addition to summarizing the ventilation-related obligations or uranium mine and mill licensee, the guide describes and discusses the ventilation-related information that licence applicants should typically submit to meet regulatory requirements. The guide pertains to any ventilation of uranium mines and mills for the purpose of assuring the radiation safety of workers and on-site personnel. This ventilation may be associated with any underground or surface area or premise that is licensable by the CNSC as part of a uranium mine or mill. These areas and premises typically include mine workings, mill buildings, and other areas or premises involving or potentially affected by radiation or radioactive materials. Some examples of the latter include offices, effluent treatment plants, cafeterias, lunch rooms and personnel change-rooms. (author)

How to Plan Ventilation Systems.

Science.gov (United States)

Clarke, John H.

1963-01-01

Ventilation systems for factory safety demand careful planning. The increased heat loads and new processes of industry have introduced complex ventilation problems in--(1) ventilation supply, (2) duct work design, (3) space requirements, (4) hood face velocities, (5) discharge stacks, and (6) building eddies. This article describes and diagrams…

Randomized, controlled trial comparing synchronized intermittent mandatory ventilation and synchronized intermittent mandatory ventilation plus pressure support in preterm infants.

Science.gov (United States)

Reyes, Zenaida C; Claure, Nelson; Tauscher, Markus K; D'Ugard, Carmen; Vanbuskirk, Silvia; Bancalari, Eduardo

2006-10-01

Prolonged mechanical ventilation is associated with lung injury in preterm infants. In these infants, weaning from synchronized intermittent mandatory ventilation may be delayed by their inability to cope with increased respiratory loads. The addition of pressure support to synchronized intermittent mandatory ventilation can offset these loads and may facilitate weaning. The purpose of this work was to compare synchronized intermittent mandatory ventilation and synchronized intermittent mandatory ventilation plus pressure support in weaning from mechanical ventilation and the duration of supplemental oxygen dependency in preterm infants with respiratory failure. Preterm infants weighing 500 to 1000 g at birth who required mechanical ventilation during the first postnatal week were randomly assigned to synchronized intermittent mandatory ventilation or synchronized intermittent mandatory ventilation plus pressure support. In both groups, weaning followed a set protocol during the first 28 days. Outcomes were assessed during the first 28 days and until discharge or death. There were 107 infants enrolled (53 synchronized intermittent mandatory ventilation plus pressure support and 54 synchronized intermittent mandatory ventilation). Demographic and perinatal data, mortality, and morbidity did not differ between groups. During the first 28 days, infants in the synchronized intermittent mandatory ventilation plus pressure support group reached minimal ventilator settings and were extubated earlier than infants in the synchronized intermittent mandatory ventilation group. Total duration of mechanical ventilation, duration of oxygen dependency, and oxygen need at 36 weeks' postmenstrual age alone or combined with death did not differ between groups. However, infants in synchronized intermittent mandatory ventilation plus pressure support within the 700- to 1000-g birth weight strata had a shorter oxygen dependency. The results of this study suggest that the addition of

Language-based communication strategies that support person-centered communication with persons with dementia.

Science.gov (United States)

Savundranayagam, Marie Y; Moore-Nielsen, Kelsey

2015-10-01

There are many recommended language-based strategies for effective communication with persons with dementia. What is unknown is whether effective language-based strategies are also person centered. Accordingly, the objective of this study was to examine whether language-based strategies for effective communication with persons with dementia overlapped with the following indicators of person-centered communication: recognition, negotiation, facilitation, and validation. Conversations (N = 46) between staff-resident dyads were audio-recorded during routine care tasks over 12 weeks. Staff utterances were coded twice, using language-based and person-centered categories. There were 21 language-based categories and 4 person-centered categories. There were 5,800 utterances transcribed: 2,409 without indicators, 1,699 coded as language or person centered, and 1,692 overlapping utterances. For recognition, 26% of utterances were greetings, 21% were affirmations, 13% were questions (yes/no and open-ended), and 15% involved rephrasing. Questions (yes/no, choice, and open-ended) comprised 74% of utterances that were coded as negotiation. A similar pattern was observed for utterances coded as facilitation where 51% of utterances coded as facilitation were yes/no questions, open-ended questions, and choice questions. However, 21% of facilitative utterances were affirmations and 13% involved rephrasing. Finally, 89% of utterances coded as validation were affirmations. The findings identify specific language-based strategies that support person-centered communication. However, between 1 and 4, out of a possible 21 language-based strategies, overlapped with at least 10% of utterances coded as each person-centered indicator. This finding suggests that staff need training to use more diverse language strategies that support personhood of residents with dementia.

Subsurface Ventilation System Description Document

Energy Technology Data Exchange (ETDEWEB)

Eric Loros

2001-07-25

The Subsurface Ventilation System supports the construction and operation of the subsurface repository by providing air for personnel and equipment and temperature control for the underground areas. Although the system is located underground, some equipment and features may be housed or located above ground. The system ventilates the underground by providing ambient air from the surface throughout the subsurface development and emplacement areas. The system provides fresh air for a safe work environment and supports potential retrieval operations by ventilating and cooling emplacement drifts. The system maintains compliance within the limits established for approved air quality standards. The system maintains separate ventilation between the development and waste emplacement areas. The system shall remove a portion of the heat generated by the waste packages during preclosure to support thermal goals. The system provides temperature control by reducing drift temperature to support potential retrieval operations. The ventilation system has the capability to ventilate selected drifts during emplacement and retrieval operations. The Subsurface Facility System is the main interface with the Subsurface Ventilation System. The location of the ducting, seals, filters, fans, emplacement doors, regulators, and electronic controls are within the envelope created by the Ground Control System in the Subsurface Facility System. The Subsurface Ventilation System also interfaces with the Subsurface Electrical System for power, the Monitored Geologic Repository Operations Monitoring and Control System to ensure proper and safe operation, the Safeguards and Security System for access to the emplacement drifts, the Subsurface Fire Protection System for fire safety, the Emplacement Drift System for repository performance, and the Backfill Emplacement and Subsurface Excavation Systems to support ventilation needs.

Subsurface Ventilation System Description Document

Energy Technology Data Exchange (ETDEWEB)

NONE

2000-10-12

The Subsurface Ventilation System supports the construction and operation of the subsurface repository by providing air for personnel and equipment and temperature control for the underground areas. Although the system is located underground, some equipment and features may be housed or located above ground. The system ventilates the underground by providing ambient air from the surface throughout the subsurface development and emplacement areas. The system provides fresh air for a safe work environment and supports potential retrieval operations by ventilating and cooling emplacement drifts. The system maintains compliance within the limits established for approved air quality standards. The system maintains separate ventilation between the development and waste emplacement areas. The system shall remove a portion of the heat generated by the waste packages during preclosure to support thermal goals. The system provides temperature control by reducing drift temperature to support potential retrieval operations. The ventilation system has the capability to ventilate selected drifts during emplacement and retrieval operations. The Subsurface Facility System is the main interface with the Subsurface Ventilation System. The location of the ducting, seals, filters, fans, emplacement doors, regulators, and electronic controls are within the envelope created by the Ground Control System in the Subsurface Facility System. The Subsurface Ventilation System also interfaces with the Subsurface Electrical System for power, the Monitored Geologic Repository Operations Monitoring and Control System to ensure proper and safe operation, the Safeguards and Security System for access to the emplacement drifts, the Subsurface Fire Protection System for fire safety, the Emplacement Drift System for repository performance, and the Backfill Emplacement and Subsurface Excavation Systems to support ventilation needs.

Intelligent ventilation in the intensive care unit

Directory of Open Access Journals (Sweden)

Sigal Sviri

2012-08-01

Full Text Available Objectives. Automated, microprocessor-controlled, closed-loop mechanical ventilation has been used in our Medical Intensive Care Unit (MICU at the Hadassah Hebrew-University Medical Center for the past 15 years; for 10 years it has been the primary (preferred ventilator modality. Design and setting. We describe our clinical experience with adaptive support ventilation (ASV over a 6-year period, during which time ASV-enabled ventilators became more readily available and were used as the primary (preferred ventilators for all patients admitted to the MICU. Results. During the study period, 1 220 patients were ventilated in the MICU. Most patients (84% were ventilated with ASV on admission. The median duration of ventilation with ASV was 6 days. The weaning success rate was 81%, and tracheostomy was required in 13%. Sixty-eight patients (6% with severe hypoxia and high inspiratory pressures were placed on pressure-controlled ventilation, in most cases to satisfy a technical requirement for precise and conservative administration of inhaled nitric oxide. The overall pneumothorax rate was less than 3%, and less than 1% of patients who were ventilated only using ASV developed pneumothorax. Conclusions. ASV is a safe and acceptable mode of ventilation for complicated medical patients, with a lower than usual ventilation complication rate.

Protective garment ventilation system

Science.gov (United States)

Lang, R. (Inventor)

1970-01-01

A method and apparatus for ventilating a protective garment, space suit system, and/or pressure suits to maintain a comfortable and nontoxic atmosphere within is described. The direction of flow of a ventilating and purging gas in portions of the garment may be reversed in order to compensate for changes in environment and activity of the wearer. The entire flow of the ventilating gas can also be directed first to the helmet associated with the garment.

46 CFR 153.312 - Ventilation system standards.

Science.gov (United States)

2010-10-01

... 46 Shipping 5 2010-10-01 2010-10-01 false Ventilation system standards. 153.312 Section 153.312... Handling Space Ventilation § 153.312 Ventilation system standards. A cargo handling space ventilation system must meet the following: (a) A ventilation system exhaust duct must discharge no less than 10 m...

In China, students in crowded dormitories with a low ventilation rate have more common colds: evidence for airborne transmission.

Directory of Open Access Journals (Sweden)

Yuexia Sun

Full Text Available OBJECTIVE: To test whether the incidence of common colds among college students in China is associated with ventilation rates and crowdedness in dormitories. METHODS: In Phase I of the study, a cross-sectional study, 3712 students living in 1569 dorm rooms in 13 buildings responded to a questionnaire about incidence and duration of common colds in the previous 12 months. In Phase II, air temperature, relative humidity and CO(2 concentration were measured for 24 hours in 238 dorm rooms in 13 buildings, during both summer and winter. Out-to indoor air flow rates at night were calculated based on measured CO(2 concentrations. RESULTS: In Phase I, 10% of college students reported an incidence of more than 6 common colds in the previous 12 months, and 15% reported that each infection usually lasted for more than 2 weeks. Students in 6-person dorm rooms were about 2 times as likely to have an incidence of common colds ≥6 times per year and a duration ≥2 weeks, compared to students in 3-person rooms. In Phase II, 90% of the measured dorm rooms had an out-to indoor air flow rate less than the Chinese standard of 8.3 L/s per person during the heating season. There was a dose-response relationship between out-to indoor air flow rate per person in dorm rooms and the proportion of occupants with annual common cold infections ≥6 times. A mean ventilation rate of 5 L/(s•person in dorm buildings was associated with 5% of self reported common cold ≥6 times, compared to 35% at 1 L/(s•person. CONCLUSION: Crowded dormitories with low out-to indoor airflow rates are associated with more respiratory infections among college students.

Architectural design of an advanced naturally ventilated building form

Energy Technology Data Exchange (ETDEWEB)

Lomas, K.J. [De Montfort University, Leicester (United Kingdom). Institute of Energy and Sustainable Development

2007-02-15

Advanced stack-ventilated buildings have the potential to consume much less energy for space conditioning than typical mechanically ventilated or air-conditioned buildings. This paper describes how environmental design considerations in general, and ventilation considerations in particular, shape the architecture of advanced naturally ventilated (ANV) buildings. The attributes of simple and advanced naturally ventilated buildings are described and a taxonomy of ANV buildings presented. Simple equations for use at the preliminary design stage are presented. These produce target structural cross section areas for the key components of ANV systems. The equations have been developed through practice-based research to design three large educational buildings: the Frederick Lanchester Library, Coventry, UK; the School of Slavonic and East European Studies, London, UK; the Harm A. Weber Library, Elgin, near Chicago, USA. These buildings are briefly described and the sizes of the as-built ANV features compared with the target values for use in preliminary design. The three buildings represent successive evolutionary stages: from advanced natural ventilation, to ANV with passive downdraught cooling, and finally ANV with HVAC support. Hopefully the guidance, simple calculation tools and case study examples will give architects and environmental design consultants confidence to embark on the design of ANV buildings. (author)

Design of Energy Efficient Hybrid Ventilation

DEFF Research Database (Denmark)

Heiselberg, Per

The focus in the development has for both systems been to minimise energy consumption while maintaining a comfortable and healthy indoor environment. The natural next step in this development is to develop ventilation concepts that utilises and combines the best features from each system......[Mechanical and natural ventilation] into a new type of ventilation system- Hybrid Ventilation....

Design and planning of the Henderson Mine ventilation upgrade project

Energy Technology Data Exchange (ETDEWEB)

Loring, D.M.; Shea, N.A. [Climax Molybdenum Co., Henderson Operations, Empire, CO (United States)

2010-07-01

The average molybdenum ore throughput at the Henderson Mine near Denver, Colorado increased significantly between 2003 and 2007. In response, the Climax Molybdenum Company updated the life-of-mine plan which resulted in significant changes to the ventilation requirements of the mine. This paper outlined the mine and ventilation planning efforts. The design options that were evaluated to upgrade the ventilation system were also described along with the final design that was chosen to support the updated mine plan. The mine uses an exhaust ventilation system in which ventilation is supplied through a service shaft, an intake shaft and a long ore haulage tunnel. Currently, air is exhausted through 2 exhaust shafts. The new reserve model that was completed in 2007 incorporated updated geologic information and mix/dilution models. An evaluation of the new life-of-mine plans and production sequences drove the development of a new ventilation plan that increased the airflow requirements of the mine. The primary design concerns were radon control; reduction of diesel particulate matter; silica dust; blasting and other gases; and climate control. Ventilation requirements were also updated based on the final exposure limits stipulated in the 2008 regulations of the Mine Safety and Health Administration. 4 refs., 11 tabs., 8 figs.

Human Response to Ductless Personalised Ventilation: Impact of Air Movement, Temperature and Cleanness on Eye Symptoms

DEFF Research Database (Denmark)

Dalewski, Mariusz; Fillon, Maelys; Bivolarova, Maria

2013-01-01

environment facially applied individually controlled air movement of room air, with or without local filtering, did not have significant impact on eye blink frequency and tear film quality. The local air movement and air cleaning resulted in increased eye blinking frequency and improvement of tear film......The performance of ductless personalized ventilation (DPV) in conjunction with displacement ventilation (DV) was studied in relation to peoples’ health, comfort and performance. This paper presents results on the impact of room air temperature, using of DPV and local air filtration on eye blink...

Ventilation system design for educational facilities

Energy Technology Data Exchange (ETDEWEB)

Elsafty, A.F.; Abo Elazm, M.M. [Arab Academy for Science, Alexandria (Egypt). Technology and Maritime Transport; Safwan, M. [Arab Academy for Science, Cairo (Egypt). Technology and Maritime Transport

2010-07-01

In order to maintain acceptable indoor air quality levels in classrooms, high ventilation rates are needed to dilute the concentration of indoor contaminants, resulting in higher energy consumption for the operation of mechanical ventilation systems. Three factors are usually considered when determining the adequate ventilation rate for classrooms in educational facilities. These include the maximum population served in the classroom; carbon dioxide (CO{sub 2}) production rate by occupants; and outdoor air conditions. CO{sub 2} concentrations usually indicate the rate of ventilation required. This paper presented a newly developed computer software program for determining the ventilation rates needed to enhance indoor air quality and to maintain CO{sub 2} concentration within the recommended levels by ANSI/ASHRAE standards for best student performance. This paper also presented design curves for determining the ventilation rates and air changes per hour required for the ventilated educational zone. 15 refs., 2 tabs., 5 figs.

Understanding mechanical ventilators.

Science.gov (United States)

Chatburn, Robert L

2010-12-01

The respiratory care academic community has not yet adopted a standardized system for classifying and describing modes of ventilation. As a result, there is enough confusion that patient care, clinician education and even ventilator sales are all put at risk. This article summarizes a ventilator mode taxonomy that has been extensively published over the last 15 years. Specifically, the classification system has three components: a description of the control variables within breath; a description of the sequence of mandatory and spontaneous breaths; and a specification for the targeting scheme. This three-level specification provides scalability of detail to make the mode description appropriate for the particular need. At the bedside, we need only refer to a mode briefly using the first or perhaps first and second components. To distinguish between similar modes and brand names, we would need to include all components. This taxonomy uses the equation of motion for the respiratory system as the underlying theoretical framework. All terms relevant to describing modes of mechanical ventilation are defined in an extensive appendix.

Airflow and Temperature Distribution in Rooms with Displacement Ventilation

DEFF Research Database (Denmark)

Jacobsen, T. V.

This thesis deals with air flow and temperature distribution in a room ventilated by the displacement principle. The characteristic features of the ventilation system are treated in the whole room but main emphasis is laid on the analysis of the stratified flow region in front of the inlet device....... After a prefatory description of the background and the fundamentals of displacement ventilation the objectives of the current study are specified. The subsequent sections describe the measurements of velocity and temperature profiles carried out in a full scale test room. Based on experimental data...... of measured data is of crucial importance. Qualitatively satisfactory results do not ensure quantitative agreement....

Large eddy simulation of a mechanically ventilated compartment fire for nuclear applications

Energy Technology Data Exchange (ETDEWEB)

Xu, Bao P. [Dalian Univ. of Technology (China). Faculty of Energy and Power Engineering; Wen, Jennifer X. [Warwick Univ. (United Kingdom). Warwick FIRE, School of Engineering

2015-12-15

This paper deals with the modelling of a mechanically ventilated compartment fire which is a commonplace in nuclear fire scenarios. An advanced Computational Fluid Dynamics (CFD) field model with a wall conjugate heat transfer treatment is proposed. It simultaneously solves the compartment fire flow and the wall heat conduction. The flow solver is based on the Large Eddy Simulation (LES) based fire simulation solver FireFOAM within the frame of open source CFD code OpenFOAM {sup registered}. An extended eddy dissipation model is used to calculate the chemical reaction rate. A soot model based on the concept of smoke point height is employed to model the soot formation and oxidation. A finite volume method is adopted to model the radiative heat transfer. The ventilation flow is modelled by a simplified Bernoulli equation neglecting the detailed information on the ventilation system. The proposed model is validated against a single room fire test with forced mechanical ventilations. The predictions are in reasonably good agreement with experimental data.

CFD Simulations of Contaminant Transport between two Breathing Persons

DEFF Research Database (Denmark)

Bjørn, Erik; Nielsen, Peter V.

Experiments have shown that exhalation from one person is able to penetrate the breathing zone of another person at a distance. Computational Fluid Dynamics (CFD) is used to investigate the dependency of the personal exposure on some physical parameters, namely: Pulmonary ventilation rate......, convective heat output, exhalation temperature, and crosssectional exhalation area. Full-scale experimental results are used to calibrate/validate the CFD model....

The impact of a ventilator bundle on preventing ventilator-associated pneumonia: a multicenter study.

Science.gov (United States)

Eom, Joong Sik; Lee, Mi-Suk; Chun, Hee-Kyung; Choi, Hee Jung; Jung, Sun-Young; Kim, Yeon-Sook; Yoon, Seon Jin; Kwak, Yee Gyung; Oh, Gang-Bok; Jeon, Min-Hyok; Park, Sun-Young; Koo, Hyun-Sook; Ju, Young-Su; Lee, Jin Seo

2014-01-01

For prevention of ventilator-associated pneumonia (VAP), a bundle approach was applied to patients receiving mechanical ventilation in intensive care units. The incidence of VAP and the preventive efficacy of the VAP bundle were investigated. A quasi-experimental study was conducted in adult intensive care units of 6 university hospitals with similar VAP rates. We implemented the VAP bundle between March 2011 and June 2011, then compared the rate of VAP after implementation of the VAP bundle with the rate in the previous 8 months. Our ventilator bundle included head of bed elevation, peptic ulcer disease prophylaxis, deep venous thrombosis prophylaxis, and oral decontamination with chlorhexidine 0.12%. Continuous aspiration of subglottic secretions was an option. Implementation of the VAP bundle reduced the VAP rate from a mean of 4.08 cases per 1,000 ventilator-days to 1.16 cases per 1,000 ventilator-days. The incidence density ratio (rate) was 0.28 (95% confidence interval, 0.275-0.292). Implementing the appropriate VAP bundle significantly decreased the incidence of VAP in patients with mechanical ventilation. Copyright © 2014 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Mosby, Inc. All rights reserved.

Fungal volatiles associated with moldy grain in ventilated and non-ventilated bin-stored wheat.

Science.gov (United States)

Sinha, R N; Tuma, D; Abramson, D; Muir, W E

1988-01-01

The fungal odor compounds 3-methyl-1-butanol, 1-octen-3-ol and 3-octanone were monitored in nine experimental bins in Winnipeg, Manitoba containing a hard red spring wheat during the autumn, winter and summer seasons of 1984-85. Quality changes were associated with seed-borne microflora and moisture content in both ventilated and non-ventilated bins containing wheat of 15.6 and 18.2% initial moisture content. All three odor compounds occurred in considerably greater amounts in bulk wheat in non-ventilated than in ventilated bins, particularly in those with wheat having 18.2% moisture content. The presence of these compounds usually coincided with infection of the seeds by the fungi Alternaria alternata (Fr.) Keissler, Aspergillus repens DeBarry, A. versicolor (Vuill.) Tiraboschi, Penicillium crustosum Thom, P. oxalicum Currie and Thom, P. aurantiogriesum Dierckx, and P. citrinum Thom. High production of all three odor compounds in damp wheat stored in non-ventilated bins was associated with heavy fungal infection of the seeds and reduction in seed germinability. High initial moisture content of the harvested grain accelerated the production of all three fungal volatiles in non-ventilated bins.

Ventilation rates and health

DEFF Research Database (Denmark)

Sundell, Jan; Levin, H; Nazaroff, W W

2011-01-01

and health effects to inform the relationship. Consistency was found across multiple investigations and different epidemiologic designs for different populations. Multiple health endpoints show similar relationships with ventilation rate. There is biological plausibility for an association of health outcomes...... studies of the relationship between ventilation rates and health, especially in diverse climates, in locations with polluted outdoor air and in buildings other than offices. PRACTICAL IMPLICATIONS: Ventilation with outdoor air plays an important role influencing human exposures to indoor pollutants...

Automated Weaning from Mechanical Ventilation after Off-Pump Coronary Artery Bypass Grafting.

Science.gov (United States)

Fot, Evgenia V; Izotova, Natalia N; Yudina, Angelika S; Smetkin, Aleksei A; Kuzkov, Vsevolod V; Kirov, Mikhail Y

2017-01-01

The discontinuation of mechanical ventilation after coronary surgery may prolong and significantly increase the load on intensive care unit personnel. We hypothesized that automated mode using INTELLiVENT-ASV can decrease duration of postoperative mechanical ventilation, reduce workload on medical staff, and provide safe ventilation after off-pump coronary artery bypass grafting (OPCAB). The primary endpoint of our study was to assess the duration of postoperative mechanical ventilation during different modes of weaning from respiratory support (RS) after OPCAB. The secondary endpoint was to assess safety of the automated weaning mode and the number of manual interventions to the ventilator settings during the weaning process in comparison with the protocolized weaning mode. Forty adult patients undergoing elective OPCAB were enrolled into a prospective single-center study. Patients were randomized into two groups: automated weaning ( n  = 20) using INTELLiVENT-ASV mode with quick-wean option; and protocolized weaning ( n  = 20), using conventional synchronized intermittent mandatory ventilation (SIMV) + pressure support (PS) mode. We assessed the duration of postoperative ventilation, incidence and duration of unacceptable RS, and the load on medical staff. We also performed the retrospective analysis of 102 patients (standard weaning) who were weaned from ventilator with SIMV + PS mode based on physician's experience without prearranged algorithm. Realization of the automated weaning protocol required change in respiratory settings in 2 patients vs. 7 (5-9) adjustments per patient in the protocolized weaning group. Both incidence and duration of unacceptable RS were reduced significantly by means of the automated weaning approach. The FiO 2 during spontaneous breathing trials was significantly lower in the automated weaning group: 30 (30-35) vs. 40 (40-45) % in the protocolized weaning group ( p  ventilation in a more protective way, reduces the

Introducing the Comprehensive Unit-based Safety Program for mechanically ventilated patients in Saudi Arabian Intensive Care Units

Directory of Open Access Journals (Sweden)

Raymond M Khan

2017-01-01

Full Text Available Over the past decade, there have been major improvements to the care of mechanically ventilated patients (MVPs. Earlier initiatives used the concept of ventilator care bundles (sets of interventions, with a primary focus on reducing ventilator-associated pneumonia. However, recent evidence has led to a more comprehensive approach: The ABCDE bundle (Awakening and Breathing trial Coordination, Delirium management and Early mobilization. The approach of the Comprehensive Unit-based Safety Program (CUSP was developed by patient safety researchers at the Johns Hopkins Hospital and is supported by the Agency for Healthcare Research and Quality to improve local safety cultures and to learn from defects by utilizing a validated structured framework. In August 2015, 17 Intensive Care Units (ICUs (a total of 271 beds in eight hospitals in the Kingdom of Saudi Arabia joined the CUSP for MVPs (CUSP 4 MVP that was conducted in 235 ICUs in 169 US hospitals and led by the Johns Hopkins Armstrong Institute for Patient Safety and Quality. The CUSP 4 MVP project will set the stage for cooperation between multiple hospitals and thus strives to create a countrywide plan for the management of all MVPs in Saudi Arabia.

Personalization of Rule-based Web Services.

Science.gov (United States)

Choi, Okkyung; Han, Sang Yong

2008-04-04

Nowadays Web users have clearly expressed their wishes to receive personalized services directly. Personalization is the way to tailor services directly to the immediate requirements of the user. However, the current Web Services System does not provide any features supporting this such as consideration of personalization of services and intelligent matchmaking. In this research a flexible, personalized Rule-based Web Services System to address these problems and to enable efficient search, discovery and construction across general Web documents and Semantic Web documents in a Web Services System is proposed. This system utilizes matchmaking among service requesters', service providers' and users' preferences using a Rule-based Search Method, and subsequently ranks search results. A prototype of efficient Web Services search and construction for the suggested system is developed based on the current work.

Assisted Ventilation in Patients with Acute Respiratory Distress Syndrome: Lung-distending Pressure and Patient-Ventilator Interaction

NARCIS (Netherlands)

Doorduin, J.; Sinderby, C.A.; Beck, J.; Hoeven, J.G. van der; Heunks, L.M.

2015-01-01

BACKGROUND: In patients with acute respiratory distress syndrome (ARDS), the use of assisted mechanical ventilation is a subject of debate. Assisted ventilation has benefits over controlled ventilation, such as preserved diaphragm function and improved oxygenation. Therefore, higher level of

Effect of nature-based sounds' intervention on agitation, anxiety, and stress in patients under mechanical ventilator support: a randomised controlled trial.

Science.gov (United States)

Saadatmand, Vahid; Rejeh, Nahid; Heravi-Karimooi, Majideh; Tadrisi, Sayed Davood; Zayeri, Farid; Vaismoradi, Mojtaba; Jasper, Melanie

2013-07-01

Few studies have been conducted to investigate the effect of nature-based sounds (N-BS) on agitation, anxiety level and physiological signs of stress in patients under mechanical ventilator support. Non-pharmacological nursing interventions such as N-BS can be less expensive and efficient ways to alleviate anxiety and adverse effects of sedative medications in patients under mechanical ventilator support. This study was conducted to identify the effect of the nature-based sounds' intervention on agitation, anxiety level and physiological stress responses in patients under mechanical ventilation support. A randomized placebo-controlled trial design was used to conduct this study. A total of 60 patients aged 18-65 years under mechanical ventilation support in an intensive care unit were randomly assigned to the control and experimental groups. The patients in the intervention group received 90 min of N-BS. Pleasant nature sounds were played to the patients using media players and headphones. Patients' physiological signs were taken immediately before the intervention and at the 30th, 60th, 90th minutes and 30 min after the procedure had finished. The physiological signs of stress assessed were heart rate, respiratory rate, and blood pressure. Data were collected over eight months from Oct 2011 to June 2012. Anxiety levels and agitation were assessed using the Faces Anxiety Scale and Richmond Agitation Sedation Scale, respectively. The experimental group had significantly lower systolic blood pressure, diastolic blood pressure, anxiety and agitation levels than the control group. These reductions increased progressively in the 30th, 60th, 90th minutes, and 30 min after the procedure had finished indicating a cumulative dose effect. N-BS can provide an effective method of decreasing potentially harmful physiological responses arising from anxiety in mechanically ventilated patients. Nurses can incorporate N-BS intervention as a non-pharmacologic intervention into the

TS LOOP ALCOVE VENTILATION ANALYSIS

International Nuclear Information System (INIS)

T.M. Lahnalampi

2000-01-01

The scope of this analysis is to examine the existing, constructor installed, physical ventilation installations located in each of the Exploratory Studies Facility (ESF) Topopah Springs (TS) Loop Alcoves No.1, No.2, No.3, No.4, No.6, and No.7. Alcove No.5 is excluded from the scope of this analysis since it is an A/E design system. Each ventilation installation will be analyzed for the purpose of determining if requirements for acceptance into the A/E design technical baseline have been met. The ventilation installations will be evaluated using Occupational Safety and Health Administration (OSHA) standards and Exploratory Studies Facility Design Requirements (ESFDR) (YMP 1997) requirements. The end product will be a technical analysis that will define ventilation installation compliance issues, any outstanding field changes, and use-as-is design deviations that are required to bring the ventilation installations into compliance with requirements for acceptance into the A/E design technical baseline. The analysis will provide guidance for alcove ventilation component design modifications to be developed to correct any deficient components that do not meet minimum requirements and standards

Mechanical ventilation for severe asthma.

Science.gov (United States)

Leatherman, James

2015-06-01

Acute exacerbations of asthma can lead to respiratory failure requiring ventilatory assistance. Noninvasive ventilation may prevent the need for endotracheal intubation in selected patients. For patients who are intubated and undergo mechanical ventilation, a strategy that prioritizes avoidance of ventilator-related complications over correction of hypercapnia was first proposed 30 years ago and has become the preferred approach. Excessive pulmonary hyperinflation is a major cause of hypotension and barotrauma. An appreciation of the key determinants of hyperinflation is essential to rational ventilator management. Standard therapy for patients with asthma undergoing mechanical ventilation consists of inhaled bronchodilators, corticosteroids, and drugs used to facilitate controlled hypoventilation. Nonconventional interventions such as heliox, general anesthesia, bronchoscopy, and extracorporeal life support have also been advocated for patients with fulminant asthma but are rarely necessary. Immediate mortality for patients who are mechanically ventilated for acute severe asthma is very low and is often associated with out-of-hospital cardiorespiratory arrest before intubation. However, patients who have been intubated for severe asthma are at increased risk for death from subsequent exacerbations and must be managed accordingly in the outpatient setting.

Wind Extraction for Natural Ventilation

Science.gov (United States)

Fagundes, Tadeu; Yaghoobian, Neda; Kumar, Rajan; Ordonez, Juan

2017-11-01

Due to the depletion of energy resources and the environmental impact of pollution and unsustainable energy resources, energy consumption has become one of the main concerns in our rapidly growing world. Natural ventilation, a traditional method to remove anthropogenic and solar heat gains, proved to be a cost-effective, alternative method to mechanical ventilation. However, while natural ventilation is simple in theory, its detailed design can be a challenge, particularly for wind-driven ventilation, which its performance highly involves the buildings' form, surrounding topography, turbulent flow characteristics, and climate. One of the main challenges with wind-driven natural ventilation schemes is due to the turbulent and unpredictable nature of the wind around the building that impose complex pressure loads on the structure. In practice, these challenges have resulted in founding the natural ventilation mainly on buoyancy (rather than the wind), as the primary force. This study is the initial step for investigating the physical principals of wind extraction over building walls and investigating strategies to reduce the dependence of the wind extraction on the incoming flow characteristics and the target building form.

Low tidal volume ventilation ameliorates left ventricular dysfunction in mechanically ventilated rats following LPS-induced lung injury.

Science.gov (United States)

Cherpanath, Thomas G V; Smeding, Lonneke; Hirsch, Alexander; Lagrand, Wim K; Schultz, Marcus J; Groeneveld, A B Johan

2015-10-07

High tidal volume ventilation has shown to cause ventilator-induced lung injury (VILI), possibly contributing to concomitant extrapulmonary organ dysfunction. The present study examined whether left ventricular (LV) function is dependent on tidal volume size and whether this effect is augmented during lipopolysaccharide(LPS)-induced lung injury. Twenty male Wistar rats were sedated, paralyzed and then randomized in four groups receiving mechanical ventilation with tidal volumes of 6 ml/kg or 19 ml/kg with or without intrapulmonary administration of LPS. A conductance catheter was placed in the left ventricle to generate pressure-volume loops, which were also obtained within a few seconds of vena cava occlusion to obtain relatively load-independent LV systolic and diastolic function parameters. The end-systolic elastance / effective arterial elastance (Ees/Ea) ratio was used as the primary parameter of LV systolic function with the end-diastolic elastance (Eed) as primary LV diastolic function. Ees/Ea decreased over time in rats receiving LPS (p = 0.045) and high tidal volume ventilation (p = 0.007), with a lower Ees/Ea in the rats with high tidal volume ventilation plus LPS compared to the other groups (p tidal volume ventilation without LPS (p = 0.223). A significant interaction (p tidal ventilation and LPS for Ees/Ea and Eed, and all rats receiving high tidal volume ventilation plus LPS died before the end of the experiment. Low tidal volume ventilation ameliorated LV systolic and diastolic dysfunction while preventing death following LPS-induced lung injury in mechanically ventilated rats. Our data advocates the use of low tidal volumes, not only to avoid VILI, but to avert ventilator-induced myocardial dysfunction as well.

Lung-protective ventilation in abdominal surgery.

Science.gov (United States)

Futier, Emmanuel; Jaber, Samir

2014-08-01

To provide the most recent and relevant clinical evidence regarding the use of prophylactic lung-protective mechanical ventilation in abdominal surgery. Evidence is accumulating, suggesting an association between intraoperative mechanical ventilation strategy and postoperative pulmonary complications in patients undergoing abdominal surgery. Nonprotective ventilator settings, especially high tidal volume (>10-12 ml/kg), very low level of positive end-expiratory pressure (PEEP, ventilator-associated lung injury in patients with healthy lungs. Stimulated by the previous findings in patients with acute respiratory distress syndrome, the use of lower tidal volume ventilation is becoming increasingly more common in the operating room. However, lowering tidal volume, though important, is only part of the overall multifaceted approach of lung-protective mechanical ventilation. Recent data provide compelling evidence that prophylactic lung-protective mechanical ventilation using lower tidal volume (6-8 ml/kg of predicted body weight), moderate PEEP (6-8 cm H2O), and recruitment maneuvers is associated with improved functional or physiological and clinical postoperative outcome in patients undergoing abdominal surgery. The use of prophylactic lung-protective ventilation can help in improving the postoperative outcome.

New modes of assisted mechanical ventilation.

Science.gov (United States)

Suarez-Sipmann, F

2014-05-01

Recent major advances in mechanical ventilation have resulted in new exciting modes of assisted ventilation. Compared to traditional ventilation modes such as assisted-controlled ventilation or pressure support ventilation, these new modes offer a number of physiological advantages derived from the improved patient control over the ventilator. By implementing advanced closed-loop control systems and using information on lung mechanics, respiratory muscle function and respiratory drive, these modes are specifically designed to improve patient-ventilator synchrony and reduce the work of breathing. Depending on their specific operational characteristics, these modes can assist spontaneous breathing efforts synchronically in time and magnitude, adapt to changing patient demands, implement automated weaning protocols, and introduce a more physiological variability in the breathing pattern. Clinicians have now the possibility to individualize and optimize ventilatory assistance during the complex transition from fully controlled to spontaneous assisted ventilation. The growing evidence of the physiological and clinical benefits of these new modes is favoring their progressive introduction into clinical practice. Future clinical trials should improve our understanding of these modes and help determine whether the claimed benefits result in better outcomes. Copyright © 2013 Elsevier España, S.L. and SEMICYUC. All rights reserved.

The pit ventilation features and the design principle of ventilation system in trackless mining uranium mine

International Nuclear Information System (INIS)

Deng Wenhui; Zhou Xinghuo; Li Xianjie

2001-01-01

According to the pit arrangement features of trackless mining uranium mine, based on the fundamental of radon permeation and control, and analysis of radon pollution characteristics and radon education, the design principle of ventilation system in trackless mining uranium mine has been raised

Impact of Residential Mechanical Ventilation on Energy Cost and Humidity Control

Energy Technology Data Exchange (ETDEWEB)

Martin, Eric [Building Science Corporation, Westford, MA (United States)

2014-01-01

Optimizing whole house mechanical ventilation as part of the Building Ameerica program's systems engineered approach to constructing housing has been an important subject of the program's research. Ventilation in residential buildings is one component of an effective, comprehensive strategy for creation and maintenance of a comfortable and healthy indoor air environment. The study described in this report is based on building energy modeling with an important focus on the indoor humidity impacts of ventilation. The modeling tools used were EnergyPlus version 7.1 (E+) and EnergyGauge USA (EGUSA). Twelve U.S. cities and five climate zones were represented. A total of 864 simulations (2*2*3*3*12= 864) were run using two building archetypes, two building leakage rates, two building orientations, three ventilation systems, three ventilation rates, and twelve climates.

Design Principles for Natural and Hybrid Ventilation

OpenAIRE

Heiselberg, Per

2000-01-01

For many years mechanical and natural ventilation systems have developed separately. Naturally, the next step in this development is the development of ventilation concepts that utilize and combine the best features from each system to create a new type of ventilation system- Hybrid Ventilation. The hybrid ventilation concepts, design challenges and principles are discussed and illustrated by four building examples.

Ventilation effectiveness : health benefits of heat recovery ventilators

Energy Technology Data Exchange (ETDEWEB)

Anon.

2010-08-15

Studies have shown that the installation of a heat recovery ventilator (HRV) in homes in northern Canada could improve indoor air quality and the respiratory health of inhabitants. Low ventilation rates are common in many homes in the North because the climate is severe, homes are smaller and lack basements, and occupancies are higher, leading to unhealthy indoor air quality. Northern communities also have a high rate of respiratory infections. HRVs recover much of the energy used to ventilate, which is desirable in cold regions with high heating costs. For the study, the test sample was divided into two types of houses, notably houses with active HRVs and those with control HRVs that were installed and operated but that did not function. The study results showed that HRVs provided increased ventilation. Complaints by residents about HRV noise, discomfort, or low humidity were common but equally spread between those with active and placebo HRVs. The study showed that the system design needs to be improved to better suit the needs of Inuit families. The nature of northern housing presents installation and maintenance challenges. It is hard to retrofit HRV ducting inside small, existing houses, and building supplies arrive infrequently, so detailed planning and careful take-offs of all supplies and materials must be done well in advance of construction. In addition, contractors are hard to locate and have variable expertise, and there is little technical follow-up. Robust technical support by local contractors and housing authorities is therefore important. 2 refs.

Modulating ventilation - low cost VAV for office buildings. [Variable Air Volume]; Modulerende ventilation - low cost VAV til kontor-bygninger. Slutrapport

Energy Technology Data Exchange (ETDEWEB)

Hoej Christensen, A.; Olsen, Hans; Drivsholm, C.

2012-02-15

The report describes a concept for renovating older existing Constant Air Volume (CAV) ventilation systems to modulating low-cost Variable Air Volume (VAV) systems. The concept is based on the total ventilated area being divided into appropriate indoor climate zones, which can cover from one to several offices with similar climate needs. For this initial climate assessment two relatively ''simple'' tools were developed that can estimate the temperature level in one room from the ventilation airflow, heat loads, etc.: - BSimFast (24-hour mean temperature calculation according to SBI-196, 2000); - BSimLight (Temperature simulation based on Danvak Textbook of Heat and Climate Technology). The concept of 'one room' can also be extended to 'one zone' with appropriate assumptions. However, only one mean room temperature is calculated. The different climate zones were equipped with Halton HFB control unit at the air supply and exhaust side. The project the following feedback options were used: - HFB unit's damper opening degree (0 to 90 degrees); - HFB unit's current flow; - HFB unit's exhaust temperature; and feedback from: - Frequency transformer (fan speed); - The central static duct pressure at the ventilation unit. In the project a control algorithm is developed that ensures a robust control of the entire ventilation system without adverse cyclic variations, based among other things on the exhaust temperature for each climate zone, and with the requirement that at least one throttle valve is always at least 80% open. It turned out that information on the current partial air volumes was necessary in addition to the individual throttle settings. Otherwise, a cyclic variations could not be controlled..Thus, it was the exhaust temperature from individual climate zones that defined the respective volumes of air. The concept was implemented on a complete CAV system and on part of a large CAV system, respectively. (LN)

Project Design Concept - Primary Ventilation System

International Nuclear Information System (INIS)

MCGREW, D.L.

2000-01-01

Tank Farm Restoration and Safe Operation (TFRSO), Project W-3 14 was established to provide upgrades that would improve the reliability and extend the system life of portions of the waste transfer, electrical, ventilation, instrumentation and control systems for the Hanford Site Tank Farms. An assessment of the tank farm system was conducted and the results are documented in system assessment reports. Based on the deficiencies identified in the tank farm system assessment reports, and additional requirements analysis performed in support of the River Protection Project (RPP), an approved scope for the TFRSO effort was developed and documented in the Upgrade Scope Summary Report (USSR), WHC-SD-W314-RPT-003, Rev. 4. The USSR establishes the need for the upgrades and identifies the specific equipment to be addressed by this project. This Project Design Concept (PDC) is in support of the Phase 2 upgrades and provides an overall description of the operations concept for the W-314 Primary Ventilation Systems. Actual specifications, test requirements, and procedures are not included in this PDC. The PDC is a ''living'' document, which will be updated throughout the design development process to provide a progressively more detailed description of the W-314 Primary Ventilation Systems design. The Phase 2 upgrades to the Primary Ventilation Systems shall ensure that the applicable current requirements are met for: Regulatory Compliance; Safety; Mission Requirements; Reliability; and Operational Requirements

A Porcine Model for Initial Surge Mechanical Ventilator Assessment and Evaluation of Two Limited Function Ventilators

Science.gov (United States)

Dickson, Robert P; Hotchkin, David L; Lamm, Wayne JE; Hinkson, Carl; Pierson, David J; Glenny, Robb W; Rubinson, Lewis

2013-01-01

Objective To adapt an animal model of acute lung injury for use as a standard protocol for a screening, initial evaluation of limited function, or “surge,” ventilators for use in mass casualty scenarios. Design Prospective, experimental animal study. Setting University research laboratory. Subjects 12 adult pigs. Interventions 12 spontaneously breathing pigs (6 in each group) were subjected to acute lung injury/acute respiratory distress syndrome (ALI/ARDS) via pulmonary artery infusion of oleic acid. Following development of respiratory failure, animals were mechanically ventilated with a limited function ventilator (Simplified Automatic Ventilator [SAVe] I or II; Automedx) for one hour or until the ventilator could not support the animal. The limited function ventilator was then exchanged for a full function ventilator (Servo 900C; Siemens). Measurements and Main Results Reliable and reproducible levels of ALI/ARDS were induced. The SAVe I was unable to adequately oxygenate 5 animals, with PaO2 (52.0 ± 11.1 torr) compared to the Servo (106.0 ± 25.6 torr; p=0.002). The SAVe II was able to oxygenate and ventilate all 6 animals for one hour with no difference in PaO2 (141.8 ± 169.3 torr) compared to the Servo (158.3 ± 167.7 torr). Conclusions We describe a novel in vivo model of ALI/ARDS that can be used to initially screen limited function ventilators considered for mass respiratory failure stockpiles, and is intended to be combined with additional studies to defintively assess appropriateness for mass respiratory failure. Specifically, during this study we demonstrate that the SAVe I ventilator is unable to provide sufficient gas exchange, while the SAVe II, with several more functions, was able to support the same level of hypoxemic respiratory failure secondary to ALI/ARDS for one hour. PMID:21187747

One more brick in the wall of protective ventilation in surgical patients

NARCIS (Netherlands)

Filho, Roberto Rabello; Serpa Neto, Ary

2015-01-01

On June 14, 2015, Ladha and colleagues published an article in the BMJ entitled "Intraoperative protective mechanical ventilation and risk of postoperative respiratory complications: hospital based registry study", which investigated the effects of intraoperative protective ventilation on major

Comparison between conventional protective mechanical ventilation and high-frequency oscillatory ventilation associated with the prone position.

Science.gov (United States)

Fioretto, José Roberto; Klefens, Susiane Oliveira; Pires, Rafaelle Fernandes; Kurokawa, Cilmery Suemi; Carpi, Mario Ferreira; Bonatto, Rossano César; Moraes, Marcos Aurélio; Ronchi, Carlos Fernando

2017-01-01

To compare the effects of high-frequency oscillatory ventilation and conventional protective mechanical ventilation associated with the prone position on oxygenation, histology and pulmonary oxidative damage in an experimental model of acute lung injury. Forty-five rabbits with tracheostomy and vascular access were underwent mechanical ventilation. Acute lung injury was induced by tracheal infusion of warm saline. Three experimental groups were formed: healthy animals + conventional protective mechanical ventilation, supine position (Control Group; n = 15); animals with acute lung injury + conventional protective mechanical ventilation, prone position (CMVG; n = 15); and animals with acute lung injury + high-frequency oscillatory ventilation, prone position (HFOG; n = 15). Ten minutes after the beginning of the specific ventilation of each group, arterial gasometry was collected, with this timepoint being called time zero, after which the animal was placed in prone position and remained in this position for 4 hours. Oxidative stress was evaluated by the total antioxidant performance assay. Pulmonary tissue injury was determined by histopathological score. The level of significance was 5%. Both groups with acute lung injury showed worsening of oxygenation after induction of injury compared with the Control Group. After 4 hours, there was a significant improvement in oxygenation in the HFOG group compared with CMVG. Analysis of total antioxidant performance in plasma showed greater protection in HFOG. HFOG had a lower histopathological lesion score in lung tissue than CMVG. High-frequency oscillatory ventilation, associated with prone position, improves oxygenation and attenuates oxidative damage and histopathological lung injury compared with conventional protective mechanical ventilation.

Protective ventilation of preterm lambs exposed to acute chorioamnionitis does not reduce ventilation-induced lung or brain injury.

Science.gov (United States)

Barton, Samantha K; Moss, Timothy J M; Hooper, Stuart B; Crossley, Kelly J; Gill, Andrew W; Kluckow, Martin; Zahra, Valerie; Wong, Flora Y; Pichler, Gerhard; Galinsky, Robert; Miller, Suzanne L; Tolcos, Mary; Polglase, Graeme R

2014-01-01

The onset of mechanical ventilation is a critical time for the initiation of cerebral white matter (WM) injury in preterm neonates, particularly if they are inadvertently exposed to high tidal volumes (VT) in the delivery room. Protective ventilation strategies at birth reduce ventilation-induced lung and brain inflammation and injury, however its efficacy in a compromised newborn is not known. Chorioamnionitis is a common antecedent of preterm birth, and increases the risk and severity of WM injury. We investigated the effects of high VT ventilation, after chorioamnionitis, on preterm lung and WM inflammation and injury, and whether a protective ventilation strategy could mitigate the response. Pregnant ewes (n = 18) received intra-amniotic lipopolysaccharide (LPS) 2 days before delivery, instrumentation and ventilation at 127±1 days gestation. Lambs were either immediately euthanased and used as unventilated controls (LPSUVC; n = 6), or were ventilated using an injurious high VT strategy (LPSINJ; n = 5) or a protective ventilation strategy (LPSPROT; n = 7) for a total of 90 min. Mean arterial pressure, heart rate and cerebral haemodynamics and oxygenation were measured continuously. Lungs and brains underwent molecular and histological assessment of inflammation and injury. LPSINJ lambs had poorer oxygenation than LPSPROT lambs. Ventilation requirements and cardiopulmonary and systemic haemodynamics were not different between ventilation strategies. Compared to unventilated lambs, LPSINJ and LPSPROT lambs had increases in pro-inflammatory cytokine expression within the lungs and brain, and increased astrogliosis (pVentilation after acute chorioamnionitis, irrespective of strategy used, increases haemodynamic instability and lung and cerebral inflammation and injury. Mechanical ventilation is a potential contributor to WM injury in infants exposed to chorioamnionitis.

The effect of a rotary heat exchanger in room-based ventilation on indoor humidity in existing apartments in temperate climates

DEFF Research Database (Denmark)

Smith, Kevin Michael; Svendsen, Svend

2016-01-01

The investigation constructed and simulated moisture balance equations for single-room ventilation with a non-hygroscopic rotary heat exchanger. Based on literature, the study assumed that all condensed moisture in the exhaust subsequently evaporated into the supply. Simulations evaluated...... the potential for moisture issues and compared results with recuperative heat recovery and whole-dwelling ventilation systems. To assess the sensitivity of results, the simulations used three moisture production schedules to represent possible conditions based on literature. The study also analyzed...... the sensitivity to influential parameters, such as infiltration rate, heat recovery, and indoor temperature. With a typical moisture production schedule, the rotary heat exchanger recovered excessive moisture from kitchens and bathrooms,which provided a mold risk. The rotary heat exchanger was only suitable...

Knowledge levels of intensive care nurses on prevention of ventilator-associated pneumonia.

Science.gov (United States)

Akın Korhan, Esra; Hakverdioğlu Yönt, Gülendam; Parlar Kılıç, Serap; Uzelli, Derya

2014-01-01

Ventilator-associated pneumonia constitutes a significant concern for ventilated patients in the intensive care unit. This study was planned to evaluate the knowledge of nurses working in general intensive care units concerning evidence-based measures for the prevention of ventilator-associated pneumonia. This study design is cross-sectional. It was carried out on nurses working in the general intensive care units of anesthiology and re-animation clinics. Collection of research data was performed by means of a Nurse Identification Form and a Form of Evidence-Based Knowledge concerning the Prevention of Ventilator-Associated Pneumonia. Characterization statistics were shown by percentage, median and interquartile range. Chi-square and Wilcoxon tests and Kruskal-Wallis tests were used as appropriate. The median value of total points scored by nurses on the questionnaire was 4.00 ± 2.00. The difference between the nurses' education levels, duration of work experience and participation in in-service training programmes on ventilator-associated pneumonia prevention and the median value of their total scores on the questionnaire was found to be statistically significant (p < 0.05). The conclusion of the study was that critical care nurses' knowledge about ventilator-associated pneumonia prevention is poor. © 2013 British Association of Critical Care Nurses.

Use of Ventilator Bundle and Staff Education to Decrease Ventilator-Associated Pneumonia in Intensive Care Patients.

Science.gov (United States)

Parisi, Maria; Gerovasili, Vasiliki; Dimopoulos, Stavros; Kampisiouli, Efstathia; Goga, Christina; Perivolioti, Efstathia; Argyropoulou, Athina; Routsi, Christina; Tsiodras, Sotirios; Nanas, Serafeim

2016-10-01

Ventilator-associated pneumonia (VAP), one of the most common hospital-acquired infections, has a high mortality rate. To evaluate the incidence of VAP in a multidisciplinary intensive care unit and to examine the effects of the implementation of ventilator bundles and staff education on its incidence. A 24-month-long before/after study was conducted, divided into baseline, intervention, and postintervention periods. VAP incidence and rate, the microbiological profile, duration of mechanical ventilation, and length of stay in the intensive care unit were recorded and compared between the periods. Of 1097 patients evaluated, 362 met the inclusion criteria. The baseline VAP rate was 21.6 per 1000 ventilator days. During the postintervention period, it decreased to 11.6 per 1000 ventilator days (P = .01). Length of stay in the intensive care unit decreased from 36 to 27 days (P = .04), and duration of mechanical ventilation decreased from 26 to 21 days (P = .06). VAP incidence was high in a general intensive care unit in a Greek hospital. However, implementation of a ventilator bundle and staff education has decreased both VAP incidence and length of stay in the unit. ©2016 American Association of Critical-Care Nurses.

Study on ventilation and noise reduction in the main transformer room in indoor substation

Directory of Open Access Journals (Sweden)

Hu Sheng

2016-01-01

Full Text Available The noise emission should be considered in the ventilation and cooling design for the main transformer room of indoor substation. In this study, based on Soundplan software, effects of four common ventilation and cooling schemes on the cooling and sound insulation were compared. The research showed that the region with low noise requirement, the ventilation could be set on the outer wall or on the door of the main transformer room, while the region with high noise requirement, air inlet muffler or ventilation through the cable interlayer under the main transformer room must be used. All of the four kinds of ventilation schemes, ventilation through the cable interlayer is the best in cooling and noise reduction.

46 CFR 153.310 - Ventilation system type.

Science.gov (United States)

2010-10-01

... 46 Shipping 5 2010-10-01 2010-10-01 false Ventilation system type. 153.310 Section 153.310... Handling Space Ventilation § 153.310 Ventilation system type. A cargo handling space must have a permanent forced ventilation system of the exhaust type. ...

Demand controlled ventilation in single-family homes; Behovstyret ventilation til enfamiliehuse

Energy Technology Data Exchange (ETDEWEB)

Rammer Nielsen, T.; Drivsholm, C.; Rudolph Hansen, M.P.; Kragh, J.

2009-12-15

This project investigated two different control strategies: A simple and cheap strategy and an advanced and expensive strategy: 1. Simple control: The ventilation rate is varied only on the whole building level giving an average ventilation rate of either 0.1 l/(s m{sup 2}) or 0.35 l/(s m{sup 2}). The air change rate is controlled by sensors in the air handling unit measuring relative humidity, temperature and CO{sub 2}. The control is based on the CO{sub 2}-concentration and absolute humidity in the supply air and exhaust air. A fixed set point for the difference in CO{sub 2}-concentration between the exhaust and supply is used to decide if the ventilation rate is low or high. As supplement to the CO{sub 2} control the difference in absolute humidity between exhaust and supply is used to assure that the ventilation remain at the high level if there is a high level of humidity in the house. 2. Advanced control: The air change rate is varied dynamically for all living rooms giving an average air change for the house between 0.1 l/(s m{sup 2}) and 0.35 l/(s m{sup 2}). The air change rate in the living rooms is controlled by CO{sub 2}-sensors in each room and dampers in the room supply duct. Relative humidity is measured in the rooms with high moisture production to ensure that the highest air exchange is activated if the relative humidity in one of these rooms is too high. Even though the two strategies have been implemented and tested for a long period of time, only the simple control can be recommended. The simple control ensures that the air quality is almost the same as if the house was ventilated constantly at the high ventilation rate. Also the simple control only requires two CO{sub 2} sensors, two relative humidity sensors and two temperature sensors in the air handling unit. These sensors should be checked from time to time e.g. when filters are exchanged. The simple control is today used in meeting rooms, office rooms and daycare facilities in a modified

Particulate pollution in ventilated space: Analysis of influencing factors

International Nuclear Information System (INIS)

Zhao Bin; Wu Jun

2009-01-01

Particle pollution has been identified to be a major indoor air pollution problem as many epidemiologic evidences have indicated that the particle exposure affects the occupant health. In common practice, mechanical ventilation is introduced to maintain a satisfactory indoor air quality for the occupant, which includes the area of particle control within the space. In order to have an effective control to the indoor particle pollution, it is important to understand the major factors influencing the indoor particle concentration in the breathing zone. This study employs a previously proposed approach to study the particle pollution in a typical ventilation system. The model simultaneously takes into account the interactions between particle transport in ventilation ducts and rooms and particle spatial distribution. It has been proven that an entire ventilation system, including filters, ducts and rooms, can be regarded as a serial of filters in steady-state cases, hence the name 'particle filter group model'. The particle concentration in the breathing zone is calculated under different conditions, and the result is then validated by experimental data. Based on the results, four main factors that affect the particle concentration in the breathing zone are identified, they are fresh air rate, particle filter efficiency, the type of the ventilation duct (roughness) and ventilation modes. Their degrees of influence are analyzed and then the possible measures to improve/control the indoor particle pollution are suggested

Invasive Mechanical Ventilation in California Over 2000-2009: Implications for Emergency Medicine

Directory of Open Access Journals (Sweden)