Search

In this study, full-scale fire experiments and numerical simulations of the underground powerhouse of a hydropower station during the construction stage were performed to investigate the temperature distribution and smoke propagation. The characteristic of inverse ambient temperature in the vertical direction was discovered, resulting in the vertical movement of smoke differing from that in a uniform temperature environment. The maximum temperature increase appeared at non-highest points. Smoke characteristic parameters such as smoke settlement height and temperature increase were discussed at different heat release rates (HRRs) of fire sources to determine the fire risk distribution of the powerhouse. Two ventilation modes were proposed, and their smoke control effects were compared. The optimal ventilation mode and volume in different fire scenarios were proposed. The findings offer scenario and data support for fire smoke control and emergency plan design in powerhouses of hydropower stations. [ABSTRACT FROM AUTHOR]

A large amount of pollutants are generated during tunnel blasting construction, which seriously endangers the life and health of construction personnel. Reasonable design and resolution of ventilation issues have become the key to ensure the safety of engineering construction. This study established a ventilation simulation engineering during tunnel construction using numerical methods of computational fluid dynamics. The mechanism of the turbulent air flow generated by the restriction of air jet and wall is proved by simulating the distribution of the flow field in the tunnel under various ventilation modes. The retarding effect of vortex conducted by air flow and pollutant transport diffusion mechanism resulted in two peak distributions of pollutants. The discharge of harmful gases has both the transport effect of the main airflow and the diffusion effect of the turbulent airflow. Jet fans can effectively accelerate the dispersion of pollutants in the vortex zone. The time cost law of ventilation saving under different ventilation modes is found through comparison. On this basis, a new annular ventilation method combining longitudinal and transverse ventilation in tunnels is proposed. Not only can it greatly save ventilation time and costs, but it also provides a very friendly solution to the residual pollutants in the vicinity of the working face. The research work of this project provides important reference and guidance value for practical engineering. Highlights: The distribution law of air flow field and the mechanism of pollutant transport and diffusion in the tunnel are revealed. A new type of ventilation mode is constructed based on numerical simulation. The advantages and disadvantages of different ventilation modes are analyzed and compared to provide guidance for practical projects. [ABSTRACT FROM AUTHOR]

Cable fires frequently occur in utility tunnels, causing incalculable economic losses. In order to reveal the smoke characteristics of an L-shaped utility tunnel cable fire under different ventilation conditions, the temperature distribution, CO concentration, and smoke spread caused by an L-shaped utility tunnel cable fire were numerically simulated. The results show that the air outlet is set on the side of the utility tunnel that is prone to ignition, and the air inlet is set on the side of the utility tunnel far away from the fire source, which is conducive to slowing down the fire temperature and reducing the diffusion rate of CO. The temperature first increases and then decreases along the longitudinal direction of the utility tunnel, taking on a single-hump shape as a whole. However, in Scenarios 4 and 7, the temperature change takes on a double-hump shape. In Scenario 3, the temperature of the utility tunnel decreases with the rise of ventilation speed, and the section that satisfies the safety standard temperature is the longest. With increase in the longitudinal length of the utility tunnel, the CO concentrations in Scenarios 1, 4, and 5 first rise and then drop, while those in Scenarios 2, 3, and 6 decrease gradually. At a ventilation speed of 1.75 m/s in Scenario 3, the CO concentration is controlled the best, and the smoke spread speed takes on a V-shaped variation pattern. Based on three factors, it is concluded that the optimal ventilation mode is a ventilation speed of 1.75 m/s in Scenario 3 (Inlet C and Outlets A and B). By studying different ventilation methods, the most suitable ventilation system for the L-shaped utility tunnel is selected to improve the fire prevention and control capabilities and reduce the loss of personnel and property caused by fire. [ABSTRACT FROM AUTHOR]

Abstract For many years, ventilation has been an essential part of advanced life support (ALS) in cardiopulmonary resuscitation (CPR). Nevertheless, there is little evidence about the best method of ventilation during resuscitation for both out-of-hospital cardiac arrest (OHCA) and inhospital cardiac arrest (IHCA) patients. Effective ventilation is one of the two main keys to successful resuscitation. In this context, the question always arises as to which airway management, along with which ventilation mode, constitutes the best strategy. Conventional ventilation modes are not designed for cardiac arrest and show important limitations that must be considered when used in CPR. Manual ventilation without the use of an automated transport ventilator (ATV) could be shown to be uncontrolled in applied volumes and pressures and should be avoided. Mechanical ventilation with an ATV is therefore superior to manual ventilation, but both volume- and pressure-controlled ventilation modes are significantly influenced by chest compressions. With the newly designed chest compression synchronized ventilation (CCSV), a special ventilation mode for resuscitation is available. Further research should be conducted to obtain more evidence of the effect of ventilation during CPR on outcomes following OHCA and not only about how to secure the airway for ventilation during CPR.

For many years, ventilation has been an essential part of advanced life support (ALS) in cardiopulmonary resuscitation (CPR). Nevertheless, there is little evidence about the best method of ventilation during resuscitation for both out-of-hospital cardiac arrest (OHCA) and inhospital cardiac arrest (IHCA) patients. Effective ventilation is one of the two main keys to successful resuscitation. In this context, the question always arises as to which airway management, along with which ventilation mode, constitutes the best strategy. Conventional ventilation modes are not designed for cardiac arrest and show important limitations that must be considered when used in CPR. Manual ventilation without the use of an automated transport ventilator (ATV) could be shown to be uncontrolled in applied volumes and pressures and should be avoided. Mechanical ventilation with an ATV is therefore superior to manual ventilation, but both volume- and pressure-controlled ventilation modes are significantly influenced by chest compressions. With the newly designed chest compression synchronized ventilation (CCSV), a special ventilation mode for resuscitation is available. Further research should be conducted to obtain more evidence of the effect of ventilation during CPR on outcomes following OHCA and not only about how to secure the airway for ventilation during CPR. [ABSTRACT FROM AUTHOR]

Mechanical ventilation is rarely a simple matter. Skill and knowledge are required to operate the ventilator modes, choose the optimal settings, and understand many monitored variables. Supporting the patient safely and effectively is the top priority in providing mechanical ventilation. This article discusses mechanical ventilation in adults. [ABSTRACT FROM AUTHOR]

Background: Cardiopulmonary bypass (CPB) is a crucial component of cardiac surgery, yet it often leads to postoperative pulmonary dysfunction (PPD). Various modes of ventilation during CPB have been employed, but their comparative effects on PPD remain unclear. Materials and Methods: This study aimed to compare different modes of ventilation--namely, conventional ventilation (CV) and protective ventilation (PV)--during CPB and assess their impact on PPD. A total of 100 patients undergoing cardiac surgery were randomly assigned to either the CV group or the PV group. Demographic data, intraoperative variables, and postoperative outcomes were recorded. PPD was assessed through pulmonary function tests (PFTs) postoperatively. Results: In the CV group, PPD was observed in 45% of patients, with a mean reduction in forced vital capacity (FVC) of 25% and forced expiratory volume in one second (FEV1) of 30%. Contrastingly, in the PV group, PPD occurred in only 20% of patients, with a mean reduction in FVC of 15% and FEV1 of 20%. The incidence of pneumonia was also significantly lower in the PV group (p < 0.05). Conclusion: Protective ventilation during CPB appears to mitigate the incidence and severity of postoperative pulmonary dysfunction compared to conventional ventilation. Employing protective ventilation strategies may contribute to improved postoperative outcomes and reduced pulmonary complications following cardiac surgery. [ABSTRACT FROM AUTHOR]

A total of 8 mechanically ventilated residential buildings and 8 naturally ventilated residential buildings were selected to analyze the pollution characteristics of indoor VOCs under different ventilation modes in the severe cold area of northeast China. On typical meteorological days in each season, VOCs were detected on site, and ventilation modes were investigated by long-term online monitoring. The test results showed that the TVOC (total volatile organic compounds) concentrations varied greatly in different seasons or different functional rooms, and the TVOC concentration was the highest in winter, with a value of 0.994 mg/m3. The kitchen was the place with the most serious VOC pollution, and the TVOC concentration could reach 1.403 mg/m3. Benzene series and methylsiloxane had the highest detection rates, but the detected concentrations were low, and the average concentrations were 0.025 mg/m3 and 0.013 mg/m3 respectively. Among the VOC types with a detection rate greater than 50%, the average proportions of aldehydes, alkanes, and benzene series were 18.7%, 15.39%, and 14.38%, respectively. And their mass ratios were also high, which were 14.90%, 30.85%, and 15.70%, respectively. The annual daily average ventilation duration of mechanically ventilated residential buildings was 7.84 h longer than that of naturally ventilated residential buildings. The median TVOC concentrations of mechanically ventilated residential buildings and naturally ventilated residential buildings were 0.621 mg/m3 and 0.707 mg/m3, respectively. The fresh air system was applicable in the severe cold area of northeast China. [ABSTRACT FROM AUTHOR]

Photovoltaic double-skin façades (PV-DSFs) have great potential to simultaneously achieve power generation, thermal insulation and natural lighting when applied in buildings. Among them, crystalline silicon PV-DSF is one of the common types due to its high efficiency and mature technology. However, the alternate arrangement of opaque crystalline silicon and transparent glass in crystalline silicon PV-DSF complicates its heat transfer characteristics. Furthermore, the ventilation air cavity in crystalline silicon PV-DSF could induce a vertical convective heat transfer process. It is difficult to accurately predict the complex multidimensional heat transfer process in crystalline silicon PV-DSF by simplified 1-D or 2-D thermal models. Therefore, a comprehensive numerical model of PV-DSF including the optics, electricity and 3-D heat transfer sub-models is developed in this paper to estimate the annual electrical and thermal properties of PV-DSF in a humid subtropical climate. The effects of structure, orientation, air cavity depth and solar cell coverage on the overall performance of PV-DSF are analyzed. In comparison with single-glazed semi-transparent photovoltaic, PV-DSF provides a 30.4% reduction in heat gain and a 50.3% reduction in heat loss. The preferred installation orientation is due south for PV-DSF in a humid subtropical climate. • A 3-D numerical heat transfer model of PV-DSF is established and validated. • The preferred installation orientation is due south for PV-DSF in a humid subtropical climate. • PV-DSF obviously reduces heat gain and loss compared to STPV glazing. • The difference in annual heat gain or loss of PV-DSF caused by different depths is tiny. [ABSTRACT FROM AUTHOR]

Background and objectives: The objective of this study was to investigate the use of early APRV mode as a lung protective strategy compared to conventional methods with regard to ARDS development. Methods: The study was designed as a randomized, non-blinded, single-center, superiority trial with two parallel groups and a primary endpoint of ARDS development. Patients under invasive mechanical ventilation who were not diagnosed with ARDS and had Lung Injury Prediction Score greater than 7 were included in the study. The patients were assigned to APRV and P-SIMV + PS mode groups. Results: Patients were treated with P-SIMV+PS or APRV mode; 33 (50.8%) and 32 (49.2%), respectively. The P/F ratio values were higher in the APRV group on day 3 (p = 0.032). The fraction of inspired oxygen value was lower in the APRV group at day 7 (p = 0.011).While 5 of the 33 patients (15.2%) in the P-SIMV+PS group developed ARDS, one out of the 32 patients (3.1%) in the APRV group developed ARDS during follow-up (p = 0.197). The groups didn’t differ in terms of vasopressor/inotrope requirement, successful extubation rates, and/or mortality rates (p = 1.000, p = 0.911, p = 0.705, respectively). Duration of intensive care unit stay was 8 (2–11) days in the APRV group and 13 (8–81) days in the P-SIMV+PS group (p = 0.019). Conclusions: The APRV mode can be used safely in selected groups of surgical and medical patients while preserving spontaneous respiration to a make benefit of its lung-protective effects. In comparison to the conventional mode, it is associated with improved oxygenation, higher mean airway pressures, and shorter intensive care unit stay. However, it does not reduce the sedation requirement, ARDS development, or mortality.

Background: The optimal airway management strategy for cardiac arrest remains unclear. This study aimed to compare the effects of different initial airway interventions on improving clinical outcomes based on the 2010 cardiopulmonary resuscitation (CPR) guidelines and later.Methods: We searched PubMed, EMBASE, and the Cochrane Library for CPR articles tailored to each database from October 19, 2010, to July 31, 2021, to compare endotracheal intubation (ETI), supraglottic airway (SGA), or bag-valve-mask ventilation (BMV). The initial results and long-term results were investigated by meta-analysis.Results: Twenty-five articles (n = 196,486) were included. The ROSC rate in the ETI group (ES = 0.49, 95% CI: 0.38-0.59) was significantly higher than that in the SGA group (ES = 0.27, 95% CI: 0.20-0.34) and BMV group (ES = 0.24, 95% CI: 0.17-0.31). The rate of ROSC upon admission to the hospital in the ETI group (ES = 0.27, 95% CI: 0.13-0.42) was significantly higher than that in the SGA group (ES = 0.18, 95% CI: 0.13-0.23) and BMV group (ES = 0.16, 95% CI: 0.10-0.22). Compared with the BMV group (ES = 0.09, 95% CI: 0.04-0.14) and the SGA group (ES = 0.08, 95% CI: 0.05-0.10), the ETI group (ES = 0.14, 95% CI: 0.10-0.17) had a higher discharge rate, but all of the groups had the same neurological outcome (ETI group [ES = 0.06, 95% CI: 0.04-0.08], BMV group [ES = 0.05, 95% CI: 0.03-0.08] and SGA group [ES = 0.04, 95% CI: 0.03-0.05]).Conclusions: Opening the airway is significantly associated with improved clinical outcomes, and the findings suggest that effective ETI based on mask ventilation should be implemented as early as possible once the patient has experienced cardiac arrest. [ABSTRACT FROM AUTHOR]

Background: The current naming of ventilation modes in anesthesiology and critical care is characterized by manufacturer-specific inconsistent acronyms. This is confusing for users and potentially life-threatening for patients. The standard, published in August 2021 in its German version as DIN EN ISO 19223:2021, aims to introduce a uniform classification with corresponding nomenclature. Aim of the work: To present the new standard and its consequences for the user. Material and method: Review and summary of DIN EN ISO 19223:2021 with a critical appraisal of its strengths and weaknesses. Results: A simplified scheme shows the group classification of ventilation modes based on similar characteristics. These are further specified by additional variables. A reference table contrasts the new nomenclature of ventilation modes with those currently in use. Accordingly, the new classification scheme appears inconsistent and the variables are difficult to distinguish. Conclusion: Standardized terminology and semantics in respiratory care are necessary and desirable for error reduction. However, the recently presented standard fulfils these expectations only to some extent and in its current form will probably lead to further ambiguities and problems in the clinical routine. Accordingly, it is imperative that this first version of DIN EN ISO 19223:2021 be understood as the starting point for a discussion of its content, even outside the standards committees, so that its obvious weaknesses can be eradicated and the nomenclature made suitable for everyday use. [ABSTRACT FROM AUTHOR]

Aiming at the problem of high winding temperature caused by the large armature winding current of permanent magnet synchronous motor (PMSM) for compressors, a 560 kW PMSM for a compressor was studied. The three dimensional global fluid-heat coupled heat transfer model is established and is discretized by the polyhedral mesh. The fluid and thermal coupling field of a permanent magnet motor are numerically calculated when the rotor rotation is considered. The temperature distribution characteristics of the end windings at different positions are analyzed. Further, the structure of the motor cooling system is improved. The effects of different ventilation modes on the temperature distribution of the motor are compared and analyzed. The temperature distribution of the stator windings under different armature currents is calculated. The calculation results of the end winding temperature are compared with the measured data, verifying the correctness of the calculation method. Conclusions have been obtained that are helpful to the design and operation of the compressor water-cooled permanent magnet synchronous motor. [ABSTRACT FROM AUTHOR]

Vehicle occupants spend prolonged durations inside the cabin due to longer commute or congested road networks. The poor in-cabin air quality and prolonged travel duration contribute a significant fraction to occupant's daily exposure levels. The intrusion of outside air pollutants inside vehicle through ventilation system and cabin leakages are recognized as dominant factors that influence the in-transit air quality. In the present study, mobile campaign was conducted from regular passenger cars to investigate the impact of vehicle characteristics, ventilation settings, fan strength, and driving speed over in-cabin particle number concentration (PNC) and air exchange rates (AERs) under realistic driving conditions. Under outside air (OA) mode, outdoor ambient air is drawn inside the vehicle cabin whereas, under recirculation (RC) mode, in-cabin air is recirculated by ventilation fan. The average in-cabin total PNC measured under OA and RC modes are 6.61E + 07 # m−3 and 2.02E + 07 # m−3 respectively. The AERs estimated under realistic driving conditions with OA and RC modes had mean (median) values of 17.44 (12.65) h−1 and 8.24 (6.99) h−1 respectively. The AERs potential influencing parameters (vehicle age, mileage, speed, cabin volume, and fan operating strength) were measured for each trip. A Generalized Estimating Equation (GEE) model was developed and outcomes revealed that vehicle age and cabin volume are statistically significant factors in determining the AERs under OA and RC modes respectively. However, vehicle speed and fan strength variables were positively associated with AERs but not statistically significant under OA mode. Highlights: Two ventilation modes were studied to assess their impact on passenger car in-cabin PNC. In-cabin total PNC reduced by 69% while commuting under RC ventilation mode. AERs vary significantly with ventilation modes and fan strength under realistic driving conditions. Shifting to highest fan strength increased the AERs by 2.73 times under OA mode. [ABSTRACT FROM AUTHOR]

A high-quality, low-cost ventilator, dubbed HEV, has been developed by the particle physics community working together with biomedical engineers and physicians around the world. The HEV design is suitable for use both in and out of hospital intensive care units, provides a variety of modes and is capable of supporting spontaneous breathing and supplying oxygen-enriched air. An external air supply can be combined with the unit for use in situations where compressed air is not readily available. HEV supports remote training and post market surveillance via a Web interface and data logging to complement standard touch screen operation, making it suitable for a wide range of geographical deployment. The HEV design places emphasis on the ventilation performance, especially the quality and accuracy of the pressure curves, reactivity of the trigger, measurement of delivered volume and control of oxygen mixing, delivering a global performance which will be applicable to ventilator needs beyond the COVID-19 pandemic. This article describes the conceptual design and presents the prototype units together with a performance evaluation.

Mechanical ventilation is associated with a number of complications that increase the cost of treatment and the hospital mortality rate. In 2004, the term «ventilator-induced diaphragm dysfunction» (VIDD) was proposed to explain one of the reasons for the failure of respiratory support. At present, this term is understood as a combination of atrophy and weakness of the contractile function of the diaphragm caused directly by a long-term mechanical lung ventilation. Oxidative stress, proteolysis, mitochondrial dysfunction, as well as passive overdistension of the diaphragm fibers contribute greatly to the pathogenesis of VIDD. Since 30—80% of patients in the ICU require mechanical respiratory support and even 6—8 hours of mechanical lung ventilation can contribute to the development of a significant weakness of the diaphragm, it can be concluded that the VIDD is an extremely urgent problem in most patients. Its typical clinical presentation is characterized by impaired breathing mechanics and unsuccessful attempts to switch the patient to the spontaneous breathing in the absence of other valid reasons for respiratory disorders. The sonography is the most informative and accessible diagnostic method, and preservation of spontaneous breathing activity and the use of the latest mechanical ventilation modes are considered a promising approach to prevention and correction of the disorders. The search for an optimal strategy for lung ventilation, development of diagnostic and physiotherapeutic methods, as well as the consolidation of the work of a multidisciplinary team of specialists (anesthesiologists and intensive care specialists, neurologists, pulmonologists, surgeons, etc.) can help in solving this serious problem. A review of 122 sources about the VIDD presented data on the background of the issue, the definition of the problem, etiology and pathogenesis, clinical manifestations, methods of diagnosis, the effect of drugs, prevention and therapy.

• DS-STPV windows with different ventilation modes were studied by simulations. • Simulation results were experimentally validated. • An optimal operational control strategy for DS-STPV windows was proposed. • Benefits with the application of DS-STPV windows were demonstrated. • DS-STPV window could improve the energy performance of buildings. The use of double-skin semitransparent photovoltaic (DS-STPV) windows is well recognized as an efficient and effective approach for enhancing the building energy performance. However, despite many studies in relation to the technology have been reported so far, there are few investigations focusing on its use in cold regions. In this study, experimental measurement data for a DS-STPV window in terms of power generation and surface temperature were compared with those obtained from EnergyPlus simulations. The measured and simulated results agreed well, which confirmed the reliability of the simulation methodology adopted. On this basis, the energy performance of DS-STPV windows with non-ventilated, inner loop, and air supply ventilation modes was analyzed by simulations performed for winter conditions in cold regions. The results showed that as compared with the other two ventilation modes, the use of air supply DS-STPV windows is capable of reducing the building net electricity use by 18.5% and 20.2%, respectively. Further, an optimal control strategy for DS-STPV windows employed in cold regions was also proposed. It was found that with the use of the proposed strategy, the building net electricity use can be effectively reduced by 3.5% and 12.3%, respectively. Relevant findings of the present study provide an insight into optimal design and control of the DS-STPV windows employed in cold regions. Further, the results presented and the simulation methodology established will also be useful for further development of the technology for energy savings and emission reductions. [ABSTRACT FROM AUTHOR]

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 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 comparable results among patients with FFMs or NMs.Conclusion: This real-life trial identified the FFM as the predominantly used interface in COPD patients undergoing long-term NIV. The increased application of FFMs is, therefore, likely to be influenced by higher IPAP levels, which form part of the basis for successful application of HI-NIV in clinical practice. Keywords: compliance, home mechanical ventilation, interfaces, masks, pressure support, ventilation modes

Despite the technological advances in the mechanical ventilation in neonatal intensive care units (NICUs), the lungs of preterm infants are still susceptible particularly to ventilator-induced lung injury. The purposes of lung-protective strategy in preterm infants are to prevent atelectrauma, limit tidal volume to avoid overdistension, and minimize oxygen toxicity. Available data suggest that these goals can be successfully achieved by different modes of respiratory support including ideal ventilation. It is important that ventilation with large tidal volumes should be avoided. Lung-protective ventilation in the newborn infants has been a recent trend as a primary mode of ventilation support for early management of respiratory distress syndrome. To reduce the risk of ventilator-induced oxygen toxicity, supplemental oxygen should be guided by pulse oximetry. In this study, current lung-protective ventilation methods in NICU are reviewed. [ABSTRACT FROM AUTHOR]

Abstract People spend nearly 90% of their time daily in various indoors, hence indoor environment is important for mortal survival and activity, which affected human health directly. Indoor particulate pollution has become an issue of increasing concern for human beings. Personnel walking behavior and ventilation mode will significantly affect the transfer characteristics of indoor particles. This paper analyzes the effect of walking process on indoor particle resuspension, and different ventilation modes (ceiling exhaust and slit exhaust) on the removal of indoor particulate concentration in experimental and theoretical models. The results show that the particle diffusion model under walking is in good agreement with the experimental results. The particles with different sizes have different diffusion characteristics during walking due to the surface deposition and resuspension rate. Particles of 1.0–3.0 μm have the fastest velocity and the largest amount in suspension, while the smallest for 0.5–1.0 μm particles. Different ventilation modes have different effects on the removal of indoor particles. The particles attenuation index is higher under slit exhaust mode, therefore the ventilation effect is higher than ceiling ventilation mode. Highlights • The effect of human walking process on indoor particle resuspension and removal was analysed. • Different size particles have different diffusion characteristics during the walking process. • Different ventilation methods have different effects on the indoor particulate matter removal. [ABSTRACT FROM AUTHOR]

Abstract People typically spend many hours a day inside their homes. Outdoor PM2.5, indoor décor, and the activities of residents worsen indoor air quality. Natural ventilation, natural ventilation with a portable air cleaner (PAC), and mechanical ventilation are some of the main ventilation modes. However, limited data are available on the actual performance of different ventilation modes. We conducted a one-year on-site program of measurement in six apartments in Tianjin, China. The results showed that indoor air quality was affected by both outdoor particle concentration and indoor activities (walking, cooking, etc.). Natural ventilation alone cannot guarantee indoor air quality. A mechanical ventilation system could reduce the duration of high indoor particulate pollution periods to some extent; however, whole year monitoring revealed that it was not effective in increasing healthy time ratios. Reduction in CO 2 concentrations above the standard levels through mechanical ventilation is 22.3% more than that through natural ventilation dwellings. Natural ventilation with a portable air cleaner can remove mass particulate pollution rapidly and maintain good indoor air quality with long-time operation. This study is expected to contribute towards the improvement of indoor air quality and the health of residents. Highlights • One-year on-site measurement in six apartments in Tianjin. • Natural ventilation alone cannot guarantee indoor air quality. • Mechanical ventilation system does little to increase healthy time ratios. • Natural ventilation with portable air cleaner can create good indoor air quality. [ABSTRACT FROM AUTHOR]

In modern society, ventilation is an important method for removing indoor particles. This study applies the parameter of attenuation index to analyse the effect of the removal of indoor particles in the two typical ventilation modes called ceiling exhaust and slit exhaust. Experiment was conducted in a chamber and riboflavin particles were used as the indoor particles source, instantaneous microbial detection (IMD) used to measure the particulate concentration. The results showed there was obvious concentration difference in the vertical distribution for the slit exhaust when indoor particles tended stable, and the smaller the particle size was, the more obvious the difference was. Air exchange rate (ACH) is an important factor affecting the indoor particle concentration distribution. In the process of indoor free settling (air exchange rate is 0 ACH), the sedimentation rate were 0.086 h −1 , 0.122 h −1 and 0.173 h −1 for the particles of 0.5–1.0 μm, 1.0–3.0 μm and 3.0–5.0 μm. When the air exchange rate increased to 2.5 ACH, the differences in the attenuation index is significant. There was also a significant linear relationship between air exchange rate and attenuation index. Furthermore, the effect of the slit exhaust mode on the removal of coarse particles is more remarkable as the increasing air exchange rate. [ABSTRACT FROM AUTHOR]

Introduction: Size 9 and 8 airways for men and women, respectively, have been proposed as most appropriate based on endoscopy. However, a limitation of this guideline is that ventilation was not assessed.Methods: In this retrospective review of prospectively collected data, 149 patients requiring tracheal intubation for general anesthesia were included. The adequacy for manual and pressure-controlled mechanical ventilation and views at the distal end of each airway was assessed using a fiber-optic bronchoscope with various airway sizes (7, 8, 9, 10, and 11).Results: For men, size 9, 10, and 11 airways permitted clear manual and adequate mechanical ventilation; size 7 and 8 airways caused partially obstructed manual and inadequate mechanical ventilation. On endoscopy, size 7 and 8 airways caused complete obstruction by the tongue; size 10 and 11 airways either touched or passed beyond the tip of the epiglottis. For women, the size 7 airway caused partially obstructed manual and inadequate mechanical ventilation; size 9 and 10 airways provided clear manual and adequate mechanical ventilation. The size 8 airway permitted clear manual ventilation, though mechanical ventilation was inadequate in one patient. On endoscopy, the size 7 airway caused complete obstruction in >50% of women; size 9, 10, and 11 airways either touched or passed beyond the tip of the epiglottis.Conclusions: With respect to adequate ventilation in conjunction with an acceptable endoscopic view, size 9 and size 8 oropharyngeal airways appear to be the most appropriate sizes for clinical use in men and women, respectively. [ABSTRACT FROM AUTHOR]

Experiment and numerical simulation were performed to research the possibility of adopting different ventilation modes for smoke confinement in a subway station fire accident. Bench scale experiments were conducted in a 1:50 scale model of a subway station. Fire Dynamics Simulator software (FDS) was utilized to carry out numerical simulations, which conducted in a full scale subway station. Experiment result agreed well with simulation result and the research showed that the different ventilation mode had different efficacy of smoke confinement released by the fire in basement 2. In addition, when the USME ventilation mode was adopted and there were smoke exhausted from basement 2 and air supplied into the basement 1, the efficacy of smoke confinement was the best. According to these cases conducted in this paper, the layouts of the ventilation vents had little influence on the efficacy of smoke confinement. Once the HRR was too big, the concentration would pass 50 PPM and the amount of exhausted smoke should be increased. [ABSTRACT FROM AUTHOR]

Twenty-eight mathematical relations for evaluation of power losses for ventilation that have found application worldwide in the 20th century are described. Limits for application of these relations are defined and the accuracy of results of ventilation loss calculations with use of these relations compared to experimental data are defined. [ABSTRACT FROM AUTHOR]

The purpose of respiration, whether artificial or spontaneous, is to get homeostasis. Mechanical ventilators are electronic, mechanical, or pneumatic devices that are doing respiration automatically according to the process of the parameters that are set by us. In the historical process, the developments in anesthesia and intensive care units have led us to classify these devices according to the actuating mechanism, the use of negative and positive pressure, occurrence of respiratory volume, or according to the ventilation period. However, many modern ventilators are complex devices with a combination of these classifications. In the near future, these devices will turn into smart devices, and all adjustments will be done automatically according to the patient's conditions. [ABSTRACT FROM AUTHOR]

Ventilation is very important during the biodrying process because it affects the biodrying efficiency and secondary pollution. In this study, three ventilation modes—intermittent negative ventilation (IN), continuous negative ventilation (CN) and intermittent positive ventilation (IP)—were used to provide the same amount of total air during biodrying of municipal solid waste (MSW). During the entire 16-day experiment, 68.4%, 68.7% and 67.2% of water contained in the initial waste was removed under IN, CN and IP trials respectively. The ratio of water loss to volatile solid loss was used to evaluate the biodrying efficiency, with values of 5.35, 5.93 and 4.82 being observed for IN, CN and IP trials respectively. The total organic carbon concentrations of the leachate generated from the biodrying of waste were as high as 25,000 mg/l, while those of the condensate were not higher than 3500 mg/l. During the entire process, the average ammonia concentrations of leachate and condensate were 1350 mg/l and 2140 mg/l respectively. From the aspect of biodrying efficiency, continuous negative ventilation was the most preferable ventilation mode for biodrying of MSW, while special care should be taken to prevent aqueous pollution if it is used in a MSW treatment plant. [ABSTRACT FROM AUTHOR]

Received June 10, 2010, and in revised form July 26, 2010. Accepted for publication August 12, 2010. Background: A number of different modalities have been employed in addition to conventional ventilation to improve oxygenation in patients with severe 2009 pandemic influenza A (H1N1) pneumonia. Outcomes with ventilatory and rescue therapies for H1N1 influenza-related acute respiratory distress syndrome (ARDS) have been varied.1–6 A single intensive care unit (ICU) experience with management of laboratory-confirmed 2009 pandemic influenza A (H1N1) ARDS with a combination of proning and airway pressure release ventilation (APRV) is described. Methods: A retrospective review of medical records of ICU patients seen at Utah Valley Regional Medical Center during the first and second waves of the H1N1 influenza pandemic was done. Results: Fourteen ICU patients were managed with invasive ventilation for 2009 pandemic influenza A (H1N1)-related ARDS. Hypoxemia refractory to conventional ventilation was noted in 11 of 14 patients despite application of APRV. Following proning in patients on APRV, improvement of hypoxemia and hemodynamic status was achieved. Only 2 of 11 patients on APRV and proning required continuous dialysis. Mortality in intubated patients receiving a combination of proning and APRV was 27.3% (3/11) with 2 of these dying during the first wave of the H1N1 influenza pandemic. In all, 3 of 11 patients on proning and APRV underwent tracheostomy, with 2 of these undergoing tube thoracostomy. ARDSnet fluid-conservative protocol was safely tolerated in 8 of 11 of the intubated patients following initiation of proning and APRV. Conclusions: Proning in combination with APRV provides improvement of hypoxemia with limitation of end-organ dysfunction and thereby facilitates recovery from severe 2009 pandemic influenza A (H1N1). [ABSTRACT FROM PUBLISHER]

Patient-ventilator interaction has been the focus of increasing attention from both manufacturers and researchers during the last 25 years. There is now compelling evidence that passive (controlled) mechanical ventilation leads to respiratory muscle dysfunction and atrophy, prolonging the need for ventilatory support and predisposing to a number of adverse patient outcomes. Although there is consensus that the respiratory muscles should retain some activity during acute respiratory failure, patient-ventilator asynchrony is now recognized as a cause of ineffective ventilation, impaired gas exchange, lung overdistention, increased work of breathing, and patient discomfort. Far more common than previously recognized, it also predisposes to respiratory muscle dysfunction and other complications, leads to excessive use of sedation, increases the duration of ventilatory support, and interferes with weaning. Appropriate recognition and management of patient-ventilator asynchrony require bedside assessment of ventilator graphics as well as direct patient observation. Among currently available ventilation modes and approaches, none has been shown to be clearly superior to all the others with respect to patient-ventilator interaction, and strongly held preferences among investigators have led to controversy and difficulties in carrying out appropriate studies evaluating them. As a result, marked practice variation exists among different specialties as well as in different institutions and geographical areas. The respected authorities on mechanical ventilation who participated in this conference differed in the modes they preferred but agreed that proper understanding and use according to the individual patient's needs are more important than which mode is chosen. Conference participants discussed the determinants, manifestations, and epidemiology of patient-ventilator asynchrony, and described and compared several ventilation modes aimed specifically at preventing and ameliorating it. The papers arising from these discussions represent the most thorough examination of this important aspect of respiratory care yet published. [ABSTRACT FROM AUTHOR]

Copyright of Intensivmedizin und Notfallmedizin is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

There has been a dramatic increase in the number and complexity of new ventilation modes over the last 30 years. The impetus for this has been the desire to improve the safety, efficiency, and synchrony of ventilator-patient interaction. Unfortunately, the proliferation of names for ventilation modes has made understanding mode capabilities problematic. New modes are generally based on increasingly sophisticated closed-loop control systems or targeting schemes. We describe the 6 basic targeting schemes used in commercially available ventilators today: set-point, dual, servo, adaptive, optimal, and intelligent. These control systems are designed to serve the 3 primary goals of mechanical ventilation: safety, comfort, and liberation. The basic operations of these schemes may be understood by clinicians without any engineering background, and they provide the basis for understanding the wide variety of ventilation modes and their relative advantages for improving patient-ventilator synchrony. Conversely, their descriptions may provide engineers with a means to better communicate to end users. [ABSTRACT FROM AUTHOR]

Assisted (interactive) breathing is generally preferred to controlled breaths in patients on mechanical ventilators. Assisted breaths allow the patient's respiratory muscles to be used, and ventilatory muscle atrophy can be prevented. Moreover, the respiratory drive of the patient does not have to be aggressively blunted. However, interactive breaths need to be synchronized with the patient's efforts during the trigger, the flow delivery, and the cycling phases. Asynchrony during any of these can put an intolerable load on the respiratory muscles, leading to fatigue and the need for a high level of sedation or even paralysis. Current ventilation modes have a number of features that can monitor and enhance synchrony, including adjustment of the trigger variable, the use of pressure-targeted versus fixed-flow-targeted breaths, and manipulations of the cycle variable. Clinicians need to know how to use these ventilation mode and monitor them properly, especially understanding the airway pressure and flow graphics. The clinical challenge is synchronizing ventilator gas delivery with patient effort. [ABSTRACT FROM AUTHOR]

Preventing ventilation-induced lung injury and bronchopulmonary dysplasia is an important goal in the care of ventilated neonates. Recently, there have been tremendous efforts to improve ventilation strategies, which aim at ventilating with a ‘protective’ and ‘open-lung’ strategy. Several different ventilation modes are now available, but it is important to note that, with regard to the neonatal pulmonary and neural outcome, there is still no clear evidence as to the superiority of one ventilation mode over another. Clinicians should bear in mind that any ventilation mode used to ventilate a neonate should be accompanied by real-time pulmonary monitoring to continuously adapt the ventilation strategy to the sudden changes in the respiratory mechanical properties of the lung. This article will describe the different ventilation modes available for neonates and highlight the importance of using a protective and open-lung ventilation strategy, even in the operating room. [Copyright &y& Elsevier]

Environmental parameters affecting the thermal comfort are; air temperature, relative humidity, mean radiant temperature and air velocities on human body segments. At this study, the effects of nonuniform and highly transient thermal comfort parameters were tested experimentally for two ventilation modes (panel vents, windshield and foot vents). With prepared simulation model thermal behavior, physiological reactions (skin temperatures) and thermal sensations of the driver were predicted. In the experiments air temperatures and velocities around the human body segments were measured at 11 and 17 different points respectively. Relative humidity measurements were performed from the head region of the driver. In the theoretical studies, dynamic and close loop Matlab-Simulink model of the human body was developed. In the simulation, the human body separated to 16 body segments to predict local dissatisfactions. The model was justified with the obtained experimental data from the literature. Studies revealed that heating the automobile compartment with panel vents mode air temperature at foot level could not reached desired values. For panel vents mode high air velocities affect driver body segments especially arms and hands owing to exposed vent air directly. This causes considerable temperature decline and low thermal sensations at skin surfaces. [ABSTRACT FROM AUTHOR]

Healthy indoor air quality (IAQ) is essential to the productivity and wellbeing of building occupants. In order to study the indoor air quality in residential buildings in Xi'an in the cold climate zone, this study selected seven natural ventilation (NV) and three mechanical ventilation (MV) samples to evaluate the levels of fine particulate matter (PM2.5) and carbon dioxide (CO 2) through long-term monitoring. The results showed that it is worth studying the ventilation options in January with the lowest outdoor temperature of −0.78 °C, and the highest PM2.5 pollution of 149 μg/m3. The monthly average operation duration of the MV showed an obvious seasonal distribution, which was consistent with the degree of outdoor pollution. Compared with NV, the short-term operation of MV cannot significantly improve indoor air quality, but better results can be achieved after increasing the operation duration. When outdoor pollution is serious, the mean daily operation duration of MV recommended in this study is greater than 9 h. The probability of excessive CO 2 concentration (above 1000 ppm) of MV was 26%, which is higher than that of NV (9%). The CO 2 concentration increased with the increase in the MV operation duration, and the indoor CO 2 concentration was proportional to the temperature difference between indoor and outdoor. The control and operation of the MV system should consider the influence of PM2.5 and CO 2 simultaneously. Long-term operation of the MV system combined with short-term NV may be a ventilation strategy suitable for IAQ control of residential buildings in Xi'an. • Xi'an suffered from the most serious outdoor PM2.5 pollution in January (149 μg/m3). • Summer needs to control the production of indoor PM2.5 and the secondary diffusion caused by NV. MV operation duration of more than 9 hours can reduce the negative impact of PM2.5. • Excessive CO 2 occurred when indoor and outdoor temperature difference was 9–12 °C. • Long-time operation MV with intermittent use of NV can simultaneously control PM2.5 and CO 2. [ABSTRACT FROM AUTHOR]

• A novel reversible photovoltaic window (RPVW) was proposed for the first time. • A numerical model of the RPVW was developed and validated. • The impact of key factors on the RPVW was revealed by parameter analysis. • The RPVW can achieve 39.78 kWh·m−2 lower electricity consumption than a common one. Photovoltaic (PV) windows are promising to reduce building net energy usage by power generation, cooling and lighting loads reduction. However, their shading effect usually leads to the rise of heating loads. A novel reversible PV window was proposed, which shared the same performance of a common one in summer but improved the solar energy utilization efficiency in winter by rotating the PV glazing into the room and reducing the heat lost to the environment. A numerical model of the proposed PV window was developed and validated with experimental data. By using the model, the thermal and electrical performance of the proposed PV window was investigated in the heating periods of Beijing and the influence of key factors on it was revealed. In comparison with a common double-glazed PV window, though the proposed one generated less electric power, its benefits from heating loads reduction outperformed the power reduction. In winter, its net electricity saving increased with the decrease of PV transparency and with the increase of glazing transmittance, and it could be 1.42–10.78, 15.67–34.57 and 18.81–39.78 kWh·m−2 lower than the reference one in naturally ventilated, non-ventilated and auto modes, respectively. [ABSTRACT FROM AUTHOR]