Effects Of Ventilation Research Articles

Comparison of the µ-opioid receptor antagonists methocinnamox (MCAM) and naloxone to reverse and prevent the ventilatory depressant effects of fentanyl, carfentanil, 3-methylfentanyl, and heroin in male rats.

The number of opioid overdose deaths has increased significantly over the past decade. The life-threatening effect of opioids is hypoventilation that can be reversed by the µ-opioid receptor (MOR) antagonist naloxone; however, because of the very short duration of action of naloxone, re-emergence of MOR agonist-induced hypoventilation can occur, requiring additional doses of naloxone. The MOR antagonist methocinnamox (MCAM) antagonizes hypoventilation by the non-morphinan fentanyl and the morphinan heroin in laboratory animals with an unusually long duration of action. Whole-body plethysmography was used to compare the potency and effectiveness of MCAM and naloxone for preventing and reversing hypoventilation by fentanyl, heroin, and the ultra-potent and longer-acting fentanyl analogs carfentanil and 3-methylfentanyl in male rats breathing normal air. Sessions comprised a 45-minute habituation period followed by intravenous (i.v.) administration of saline or an acute dose of MOR agonist. The rank order of potency to decrease ventilation was 3-methylfentanyl > carfentanil > fentanyl > heroin. MCAM (0.0001-0.1 mg/kg) and naloxone (0.0001-0.01 mg/kg) dose-dependently reversed hypoventilation by 3-methylfentanyl (0.01 mg/kg), carfentanil (0.01 mg/kg), fentanyl (0.1 mg/kg), or heroin (3.2 mg/kg). For prevention studies, MCAM, naloxone, or vehicle was administered i.v. 22, 46, or 70 hours prior to a MOR agonist. When administered 22 hours earlier, MCAM (0.1-1.0 mg/kg) but not naloxone (1.0 mg/kg) prevented hypoventilation by each MOR agonist. This study demonstrates the effectiveness of MCAM to reverse and prevent hypoventilation by MOR agonists including ultra-potent fentanyl analogs that have a long duration of action. Significance Statement The number of opioid overdose deaths increased over the past decade despite the availability of antagonists that can prevent and reverse the effects of opioids. This study demonstrates the effectiveness and long duration of action of the µ-opioid receptor (MOR) antagonist methocinnamox (MCAM) for reversing and preventing hypoventilation by MOR agonists including ultra-potent fentanyl analogs. These results provide support for the notion that MCAM has the potential to positively impact the ongoing opioid crisis by reversing and preventing opioid overdose.

The Effect of Positive Pressure Ventilation on Acute Kidney Injury in COVID-19 Patients with Acute Respiratory Distress Syndrome: An Observational Study

Introduction: Acute kidney injury (AKI) is frequent in critically ill COVID-19 patients and is associated with a higher mortality risk. By increasing intrathoracic pressure, positive pressure ventilation (PPV) may reduce renal perfusion pressure by reducing venous return to the heart or by increasing renal venous congestion. This study’s aim was to evaluate the association between AKI and haemodynamic and ventilatory parameters in COVID-19 patients with ARDS. Methods: This is a single-centre retrospective observational study. Consecutive patients diagnosed with COVID-19 who met ARDS criteria and required invasive mechanical ventilation were enrolled. The relationship between respiratory and haemodynamic parameters influenced by PPV and AKI development was evaluated. AKI was defined according to KDIGO criteria. AKI recovery was evaluated a month after ICU admission and patients were classified as “recovered,” if serum creatinine (sCr) value returned to baseline, or as having “acute kidney disease” (AKD), if criteria for AKI stage 1 or greater persisted. The 6-month all-cause mortality was collected. Results: A total of 144 patients were included in the analysis. AKI occurred in 69 (48%) patients and 26 (18%) required renal replacement therapy. In a multivariate logistic regression analysis, sex, hypertension, cumulative dose of furosemide, fluid balance, and plateau pressure were independently associated with AKI. Mortality at 6 months was 50% in the AKI group and 32% in the non-AKI group (p = 0.03). Among 36 patients who developed AKI and were discharged alive from the hospital, 56% had a full renal recovery after a month, while 14%, 6%, and 14% were classified as having an AKD of stage 0, 2, and 3, respectively. Conclusions: In our cohort, AKI was independently associated with multiple variables, including high plateau pressure, suggesting a possible role of PPV on AKI development. Further studies are needed to clarify the role of mechanical ventilation on renal function.

Infection Prevention and the Protective Effects of Unidirectional Displacement Flow Ventilation in the Turbulent Spaces of the Operating Room.

Unidirectional displacement flow (UDF) ventilation systems in operating rooms are characterized by a uniformity of velocity ≥80% and protect patients and operating room personnel against exposure to hazardous substances. However, the air below the surgical lights and in the surrounding zone is turbulent, which impairs the ventilation system's effect. We first used the recovery time (RT) as specified in International Organization for Standardization 14644 to determine the particle reduction capacity in the turbulent spaces of an operating room with a UDF system. The uniformity of velocity was analyzed by comfort-level probe grid measurements in the protected area below a hemispherical closed-shaped and a semi-open column-shaped surgical light (tilt angles: 0°/15°/30°) and in the surrounding zone of a research operating room. Thereafter, RTs were calculated. At a supply air volume of 10,500 m3/h, the velocity, reported as average uniformity ± standard deviation, was uniform in the protected area without lights (95.8% ± 1.7%), but locally turbulent below the hemispherical closed-shaped (69.3% ± 14.6%), the semi-open column-shaped light (66.9% ± 10.9%), and in the surrounding zone (51.5% ± 17.6%). The RTs ranged between 1.1 and 1.7 min below the lights and 3.5 ± 0.28 min in the surrounding zone and depended exponentially on the volume flow rate. Compared to an RT of ≤20 min as required for operating rooms with mixed dilution flow, particles here were eliminated 12-18 times more quickly from below the surgical lights and 5.7 times from the surrounding zone. Thus, the effect of the lights was negligible and the UDF's retained its strong protective effect.

Study on the Modified Ventilation Network on the Ventilation Effect and Ozone Migration Characteristics in Grain Pile

Grain is an important material for human survival. However, the expanding world population is contributing to a growing grain shortage. In order to reduce the loss of grain due to pests and mold during storage, mechanical ventilation as the main method of ventilation has crucial research significance. This article proposed and analyzed the ventilation effect and the migration characteristics of ozone in the grain pile under the modified ventilation network (MVN) and compared it with the original ventilation network (OVN). The study found that the temperature, moisture, and ozone concentration in the grain pile of the two ventilation networks are not evenly distributed in the vertical direction, showing a layered pattern. That is, with an increase in grain stack height, the temperature and moisture content of the grain stack are higher, and the ozone concentration is lower. Moreover, in the pre-ventilation period, the average temperature decline rate of the MVN was 1.25 °C/d, which was better than that of the OVN (0.84 °C/d), and the maximum temperature difference between the MVN and the OVN was 0.89 °C. The vertical ducts added to the MVN improved the ventilation effect, maintaining high ozone concentrations within the grain pile. Notably, on the sixth day of fumigation, the average ozone concentration of the MVN exceeded that of the OVN. The MVN can solve the shortcomings of the OVN, where air intake and fumigation gas rise slowly in the vertical direction. These findings hold substantial significance for optimizing ventilation network structures, devising effective fumigation strategies, and enhancing the insecticidal effects of grain storage.

Noninvasive Electromagnetic Phrenic Nerve Stimulation in Critically Ill Patients: A Feasibility Study

BackgroundElectromagnetic stimulation of the phrenic nerve induces diaphragm contractions, but no coils for clinical use have been available. We recently demonstrated the feasibility of ventilation using bilateral transcutaneous non-invasive electromagnetic phrenic nerve stimulation (NEPNS) preoperatively in lung-healthy, normal-weight patients in a dose-dependent manner. Research QuestionIs NEPNS feasible in critically ill patients in an ICU setting? Study Design and MethodsThis feasibility non-randomized controlled study aimed to enroll patients within 36h of intubation, who were expected to remain ventilated for ≥72h. The intervention group received 15-minute bilateral transcutaneous NEPNS twice daily, while the control group received standard care. If sufficient, NEPNS was used without pressure support to ventilate the patient; pressure support was added if necessary to ventilate the patient adequately. The primary outcome was feasibility, measured as time to find the optimal stimulation position. Further endpoints were sessions performed according to the protocol or allowing a next-day catch-up session and tidal volume achieved with stimulation only reaching 3-6ml/kgIBW. A secondary endpoint was expiratory diaphragm thickness measured with ultrasound from Day 1 to 10 (or extubation). ResultsThe revised EU regulation mandated reapproval of medical devices, prematurely halting the study. Eleven patients (5 intervention, 6 control) were enrolled. The time to find an adequate stimulation position was 23 [12-62] seconds. The intervention twice daily was executed in 87% of cases, and 92% including a next-day catch-up session. Ventilation with 3-6ml/kgIBW was achieved in 732/1701 (43.0%) of stimulations with stimulation only and in 2511/4036 (62.2%) with additional pressure support. A decrease in diaphragm thickness was prevented by bilateral NEPNS (p=0.034) until day 10. InterpretationBilateral transcutaneous NEPNS was feasible in the ICU setting with the potential benefit of preventing diaphragm atrophy during mechanical ventilation; NEPNS ventilation effectiveness needs further assessment.

“Parametric study on the age of air in a full-scale office room using perforated duct diffusers.”

Following the recent pandemic of COVID-19, scientists have made many efforts to devise a workable solution for it, worldwide. However, it was shown that the protective effect of a well-conditioning system is as high as five times in comparison to the face-covering and other proposed procedures. In this context, the age of air and the type of filtration systems in closed spaces became the critical criteria for comparing the capability of ventilation systems. In this paper, a validated numerical model for the perforated duct diffusers is used to study the behaviour of the local age of air at the full-scale office with 8 feet (2.44 [m]) height, under various initial conditions like initial velocity and air change per hour. Also, different geometries for the ducts have been investigated under the same initial condition, as well as the effect of direction, ventilation effectiveness, and flow pattern. Finally, the volume average of the age of air at different zones has been nominated to perform the sensitivity analysis of each variable based on the variation of the airflow. The results show that diffusers with vertical perforations would be more effective during the pandemic than the other types in airborne mitigation. Moreover, the highest available airflow shall be set until such time there is no windy area in the breathing zone. Within these modifications, the residence time of the infectious nuclei in the breathing zone may decrease by up to 30%.

Combination of high-flow nasal oxygen and ketamine/dexmedetomidine sedation for diagnostic catheterization in a child with pulmonary arterial hypertension: a case report

Pulmonary hypertension is associated with significant risk of perioperative life-threatening events. We present a case of a 12-year-old child with severe pulmonary arterial hypertension who successfully underwent diagnostic cardiac catheterization under ketamine and dexmedetomidine sedation with the support of high-flow nasal oxygen. Ketamine and dexmedetomidine are reported to have minimal effect on pulmonary vasculature in children with pulmonary hypertension and can be safely used in this population along with its lack of respiratory depression. Positive pressure generated by high-flow nasal oxygen improves upper airway patency, prevents micro-atelectasis, and is shown to improve the effectiveness of ventilation and oxygenation in patients under sedation breathing spontaneously. The presented strategy may contribute to enhancing the safety and effectiveness of procedural sedation for children with life-threatening pulmonary hypertension.

Comparison of nasal and face mask ventilation in anaesthetised obese adults: A randomised controlled study.

The use of a face mask while inducing general anaesthesia (GA) in obese patients is often ineffective in providing adequate ventilation. Although nasal mask ventilation has demonstrated effectiveness for continuous positive airway pressure (CPAP) in obese patients with obstructive sleep apnoea (OSA), it has not yet been applied to the induction of anaesthesia. This study evaluated the efficacy of nasal mask ventilation against standard face mask ventilation in anaesthetised obese patients with body mass index (BMI)>25 kg/m2. Ninety adult patients with BMI >25 kg/m2 were randomly assigned to receive either facemask (Group FM) or nasal-mask (Group NM) ventilation during induction of GA. Expired tidal volume (VtE), air leak, peak inspiratory pressure (PIP), plateau pressure (PPLAT), oxygen saturation (SpO2), and end-tidal carbon dioxide (EtCO2) were recorded for10 breaths, and their mean was analysed. The mean (standard deviation) VtE measured was not significantly higher in Group NM [455.98 (55.64) versus 436.90 (49.50) mL, P = 0.08, degree of freedom (df):88, mean difference (95% confidence interval [CI]) -19.08 (-41.14, 2.98) mL]. Mean air-leak [16.44 (22.16) versus 31.63 (21.56) mL, P = 0.001, df: 88, mean difference 95%CI: 15.19 (6.03,24.35)], mean PIP [14.79 (1.39) versus 19.94 (3.05) cmH2O, P = 0.001, df: 88, mean difference, 95%CI: 5.15 (4.16, 6.14)], and mean PPLAT [12.04 (1.21) versus 16.66 (2.56) cmH2O, P = 0.001, df: 88, mean difference 95% CI: 4.62 (3.78, 5.45)] were significantly lower in Group NM. EtCO2, SpO2, and haemodynamic measurements were similar between the two groups. Nasal mask ventilation is an effective ventilation method and can be used as an alternative to face mask ventilation in anaesthetised obese adults with BMI>25 kg/m2.

Make Way for the Wind—Promoting Urban Wind Corridor Planning by Integrating RS, GIS, and CFD in Urban Planning and Design to Mitigate the Heat Island Effect

Under the trend in climate change, global warming, and the increasingly serious urban heat island effect, promoting urban wind corridor planning to reduce urban temperature and mitigate the effect of urban heat islands has received widespread attention in many cities. With emerging awareness of the need to explicitly incorporate climate considerations into urban planning and design, integrating current spatial analysis and simulation tools to enhance urban wind corridor planning to obtain the best urban ventilation effect has become an increasingly important research topic in green city development. However, how to systematically carry out urban wind corridor planning by employing related technology and simulation tools is a topic that needs to be explored urgently in both theory and practice. Taking Zhumadian City in China as an example, this study proposes a method and planning approach that uses remote sensing (RS), geographic information system (GIS), and computational fluid dynamics (CFD) in an integrated way to understand urban landscape and to conduct urban wind corridor planning. The research results reveal that the urban form of Zhumadian City favors the development of urban wind corridors, and that the railway lines and some major roads in the city have the potential to be developed as the city’s main wind corridors. However, there are still ventilation barriers resulting from the existing land use model and building layout patterns that need to be adjusted. In terms of local-level analysis, the CFD simulation analysis also reveals that some common building layout patterns may result in environments with poor ventilation. Finally, based on the results of our empirical analysis and local planning environment, specific suggestions are provided on how to develop appropriate strategies for urban wind corridor planning and adjustments related to land use planning and building layout patterns in order to mitigate the impact of the urban heat island effect.

Experimental study of buoyancy-driven ventilation with a single opening between two adjacent building zones

In adjacent building zones connected by a single opening, a thermal plume produces a buoyant layer accumulating in the upper space of the experimental zone. The pressure difference between inside and outside the chamber will lead to air flowing in from outside and buoyant fluid flowing out from inside. This study aims to examine the effect of the vertical opening combination on flow regimes in adjacent building zones. The findings indicate that there may be three different flow regimes depending on the relative positions of the opening in the shared wall and the neutral level. The steady flow in two regimes with double stratification formed in the two zones is modeled separately and the theoretical prediction is compared with the experimental results. The flow regime of natural ventilation in the adjacent zones is only related to the height of the outlet, heat source height and effective opening area of the ventilation zones, but not to the buoyancy flux. The interface changes linearly with the height of the heat source at first until the nozzle is immersed in the buoyancy layer, and then the interface height remains constant. The relative size of the openings will also affect the volume flow rate through them, and keeping the areas of the openings along the flow passage equal will maximize the ventilation rate. These research results can provide layout guidelines for building doors and windows and will help designer improve the natural ventilation effect of adjacent building zones.

Characterization of the deflagration behavior of the lithium-ion battery module within a confined space under different ventilation conditions

Lithium-ion batteries (LIBs) have been widely used in the modern society, such as electric vehicle and energy storage system. The most common application scenario of LIB is in the confined space. LIBs were prone to release flammable gases (such as carbon monoxide, hydrogen, and hydrocarbons) under abuse conditions, and the gas accumulation deflagrated with catastrophic power especially in the confined space. The ventilation condition and cathode materials of the LIB influence the destructive power of deflagration. In this study, thermal runaway (TR) tests on the Li(Ni0.8Co0.1Mn0.1)O2 (NCM811) and Li(Ni0.6Co0.2Mn0.2)O2 (NCM622) cells with different states of charge (SOCs) were conducted in a confined box under different ventilation conditions. The location of peak pressure, gas temperature, deflagration pressure, and the effects of ventilation were analyzed. Based on the measured values of the pressure at different locations, the peak pressure was generally located at the top of the confined space. The gas temperature and pressure of NCM811 batteries were generally higher than those of NCM622 batteries. NCM811 cells not only had a lower trigger temperature of thermal runaway (TR), but also a high destructive power of deflagration. The impact of ventilation condition on deflagration was studied, and the result of dimensionless analysis indicated that the deflagration pressure was influenced by opening factor, explosion gas volume, explosion heat, and explosion temperature. With the increasing of the opening angle of the window, the peak deflagration pressure firstly increased (from 30° to 60°) then decreased, indicating that there was an competitive mechanism between the combustion and pressure relief with the improvement of ventilation condition. This work helps us understand the hazards of LIB deflagration under different ventilation conditions and provides a reference for ventilation design in battery application scenarios which ensure the process safety through fire protection design.

Effects of weights applied to the apex of a bag-valve-mask and pinch strength on tidal volume: a prospective simulation study

A bag-valve-mask (BVM) is a first aid tool that can easily and quickly provide positive-pressure ventilation in patients with breathing difficulties. The most important aspect of BVM bagging is how closely the mask adheres to the patient’s face when the E–C technique is used. In particular, the greater the adhesion force at the apex of the mask, the greater the tidal volume. The purpose of this study was to investigate the effect of various weights applied to the mask’s apex and the pinch strength needed to perform the E–C technique, on tidal volume. In this prospective simulation study, quasi-experimental and equivalent time-series designs were used. A total of 72 undergraduate paramedic student from three universities were recruited using convenience sampling. The tidal volumes according to the weights (0 g, 100 g, 200 g, 300 g) applied to the apical area of the mask, handgrip strength, and pinch strength (tip pinch strength, key pinch strength, and tripod pinch strength) were measured. A linear mixed model analysis was performed. Linear mixed model analyses showed that tidal volume was significantly higher at 200 g (B = 43.38, p = 0.022) and 300 g (B = 38.74, p = 0.017) than at 0 g. Tripod pinch strength (B = 12.88, p = 0.007) had a significant effect on mask adhesion for effective BVM ventilation. Adding weight to the apical area of the mask can help maintain the E–C technique and enable effective ventilation. Future studies are required to develop specific strategies to improve the ventilation skills, which can be an important first-aid activity.

The Effect of Recruitment Maneuvers on Cerebrovascular Dynamics and Right Ventricular Function in Patients with Acute Brain Injury: A Single-Center Prospective Study.

Optimization of ventilatory settings is challenging for patients in the neurointensive care unit, requiring a balance between precise gas exchange control, lung protection, and managing hemodynamic effects of positive pressure ventilation. Although recruitment maneuvers (RMs) may enhance oxygenation, they could also exert profound undesirable systemic impacts. The single-center, prospective study investigated the effects of RMs (up-titration of positive end-expiratory pressure) on multimodal neuromonitoring in patients with acute brain injury. Our primary focus was on intracranial pressure and secondarily on cerebral perfusion pressure (CPP) and other neurological parameters: cerebral autoregulation [pressure reactivity index (PRx)] and regional cerebral oxygenation (rSO2). We also assessed blood pressure and right ventricular (RV) function evaluated using tricuspid annular plane systolic excursion. Results are expressed as the difference (Δ) from baseline values obtained after completing the RMs. Thirty-two patients were enrolled in the study. RMs resulted in increased intracranial pressure (Δ = 4.8mm Hg) and reduced CPP (ΔCPP = -12.8mm Hg) and mean arterial pressure (difference in mean arterial pressure = -5.2mm Hg) (all p < 0.001). Cerebral autoregulation worsened (ΔPRx = 0.31 a.u.; p < 0.001). Despite higher systemic oxygenation (difference in partial pressure of O2 = 4mm Hg; p = 0.001) and unchanged carbon dioxide levels, rSO2 marginally decreased (ΔrSO2 = -0.5%; p = 0.031), with a significant drop in arterial content and increase in the venous content. RV systolic function decreased (difference in tricuspid annular plane systolic excursion = -0.1cm; p < 0.001) with a tendency toward increased RV basal diameter (p = 0.06). Grouping patients according to ΔCPP or ΔPRx revealed that those with poorer tolerance to RMs had higher CPP (p = 0.040) and a larger RV basal diameter (p = 0.034) at baseline. In patients with acute brain injury, RMs appear to have adverse effects on cerebral hemodynamics. These findings might be partially explained by RM's impact on RV function. Further advanced echocardiography monitoring is required to prove this hypothesis.

Zonal demand-controlled ventilation strategy to minimize infection probability and energy consumption: A coordinated control based on occupant detection

Due to the outbreak of COVID-19, an increased risk of airborne transmission has been experienced in buildings, particularly in confined public places. The need for ventilation as a means of infection prevention has become more pronounced given that some basic precautions (like wearing masks) are no longer mandatory. However, ventilating the space as a whole (e.g., using a unified ventilation rate) may lead to situations where there is either insufficient or excessive ventilation in localized areas, potentially resulting in localized virus accumulation or large energy consumption. It is of urgent need to investigate real-time control of ventilation systems based on local demands of the occupants to strike a balance between infection risk and energy saving. In this work, a zonal demand-controlled ventilation (ZDCV) strategy was proposed to optimize the ventilation rates in sub-zones. A camera-based occupant detection method was developed to detect occupants (with eight possible locations in sub-zones denoted as ‘A’ to ‘H’). Linear ventilation model (LVM), dimension reduction, and artificial neural network (ANN) were integrated for rapid prediction of pollutant concentrations in sub-zones with the identified occupants and ventilation rates as inputs. Coordinated ventilation effects between sub-zones were optimized to improve infection prevention and energy savings. Results showed that rapid prediction models achieved an average prediction error of 6 ppm for CO2 concentration fields compared with the simulation under different occupant scenarios (i.e., occupant locations at ABH, ABCFH, and ABCDEFH). ZDCV largely reduced the infection risk to 2.8% while improved energy-saving efficiency by 34% compared with the system using constant ventilation rate. This work can contribute to the development of building environmental control systems in terms of pollutant removal, infection prevention, and energy sustainability.

Impact of climate change on the potential of free-cooling strategies for a retrofitted building in a hot climate

This paper’s objective and novelty is to understand the impact of different natural ventilation strategies as well as the effect of a proposed smart controlled ventilation strategy on cooling energy saving and thermal comfort in a residential building. Afterwards, an investigation of the Climatic Potential of Natural Ventilation (CPNV) in hot and dry climates, and particularly the potential of the night ventilation strategy under present and future climates, was made. Two prediction climate change scenarios, RCPs 2.6 and 8.5, were considered for two periods. The results, obtained by a validated simulation, have shown the beneficial effect of night ventilation, since it could reduce cooling load by 9% and would keep the operative temperature below 30°C. Nevertheless, the potential of this natural ventilation strategy would be reduced in the future due to climate change. Indoor overheating has been projected to increase drastically. The summer thermal behaviour will be greatly aggravated in the future. Indeed, the CPNV in the summer nights will be decreased by 25%. However, the climate change will affect the winter natural ventilation potential in the future. The results also highlighted that the annual Total Climatic Potential of Natural Ventilation could be increased by 1% for RCP 2.6 and decreased by 4.9% for RCP 8.5.

A Comprehensive Index for Evaluating the Effectiveness of Ventilation-Related Infection Prevention Measures with Energy Considerations: Development and Application Perspectives

In the wake of the COVID-19 pandemic, prioritizing indoor air quality has emerged as a crucial measure for preventing infections. Effective ventilation is vital in mitigating airborne pathogen transmission and maintaining a healthy indoor environment by diluting and removing infectious particles from enclosed spaces. However, increasing the supply of pathogen-free air to enhance infection control can lead to a rise in energy consumption. Nevertheless, evaluating the overall efficacy of ventilation-based infection prevention strategies while considering their energy requirements has posed challenges. This scientific paper introduces the ICEE (Infection Control’s Energy Efficiency) index, a newly developed simple integrated index to assess the effectiveness of ventilation strategies in reducing infection risks while accounting for associated energy demands. The paper reviews the current understanding of ventilation strategies, their impact on infection prevention, and their corresponding energy consumption. By employing a straightforward analytical approach, this metric offers a comprehensive framework to optimize ventilation systems for both infection prevention and energy efficiency. To quantify infection risk, a simplified equation model is utilized, incorporating factors such as ventilation effectiveness and filter efficiency, in case of recirculation. Energy demand is determined using approximations and relevant values from existing literature. Reference cases are defined, distinguishing between natural and mechanically ventilated scenarios, as these reference situations influence the energy-related effects of any implemented measures. The paper outlines the methodology employed to develop the index and illustrates its applicability through exemplary measures. The proposed index yields valuable insights for the design, operation, and retrofitting of ventilation systems, enabling informed decision-making towards fostering a healthier and more sustainable built environment.

Far too many unnecessary deaths during corona?

‚This is about excess mortality and its measurement based on available data. It‘s about the effects of corona on inpatient care and the effect of forced ventilation in intensive care. And it is about evidence on collateral damage and the long-term effects of the decline in hospital cases for other diseases during corona.‘ With these words, MVF editor Prof Dr Reinhold Roski outlined the range of topics covered in the second part of the MVF Congress ‚Pandemic impact on care‘. Roski continued: ‚We need a reappraisal and a learning process must begin - we want to contribute to this today, because healthcare research has a decisive contribution to make.‘

Assessment of land use change of ecological green wedge and cooling island effect: A case study of Wuhan, China.

The construction of urban ecological green wedges, which can mitigate the heat island effect through cooling and ventilation effects, is an important way to enhance the adaptation of cities to climate change. Dynamic monitoring and periodic assessment of both the conservation status and cooling effect of ecological green wedges is a key to ensure the heat mitigation benefits. Based on multi-source remote sensing data, we systematically analyzed the land use changes of six ecological green wedges in Wuhan in 2013 and 2020 using the methods of Markov transfer matrix, land use dynamics, and comprehensive index of land use degree, and evaluated the changes in surface temperature of the ecological green wedges and their cooling island effect. Results showed that the ecological green wedges in Wuhan generally had a large amount of construction land encroaching on ecological land from 2013 to 2020, with the water decreased the most. With the continuous deterioration of ecological green wedges, their land surface temperatures showed rising trends, together with significant weakening trends in cooling island effects. Among all the six wedges, the Dadonghu, Tangxun, and Wuhu exhibited relatively better ecological conservation, slighter land use change and lower overall development degree. Qinglinghu and Houguanhu demonstrated average levels of conservation. Fuhe experienced the most severe change under the significant influence of the westward policy of Wuhan City, with the proportion of water decreasing by 7.1%, warming up by 3.00 ℃, and the largest reduction in cooling distance for the cooling island effect, amounting to about 210 m. The results provided scientific evidence for the urban heat island mitigation-oriented planning and management of ecological green wedges for Wuhan City.

Impact of mechanical power and positive end expiratory pressure on central vs. mixed oxygen and carbon dioxide related variables in a population of female piglets.

The use of the pulmonary artery catheter has decreased overtime; central venous blood gases are generally used in place of mixed venous samples. We want to evaluate the accuracy of oxygen and carbon dioxide related parameters from a central versus a mixed venous sample, and whether this difference is influenced by mechanical ventilation. We analyzed 78 healthy female piglets ventilated with different mechanical power. There was a significant difference in oxygen-derived parameters between samples taken from the central venous and mixed venous blood (S O2 = 74.6%, ScvO2 = 83%, p < 0.0001). Conversely, CO2-related parameters were similar, with strong correlation. Ventilation with higher mechanical power and PEEP increased the difference between oxygen saturations, (Δ[ScvO2-S O2 ] = 7.22% vs. 10.0% respectively in the low and high MP groups, p = 0.020); carbon dioxide-related parameters remained unchanged (p = 0.344). The venous oxygen saturation (central or mixed) may be influenced by the effects of mechanical ventilation. Therefore, central venous data should be interpreted with more caution when using higher mechanical power. On the contrary, carbon dioxide-derived parameters are more stable and similar between the two sampling sites, independently of mechanical power or positive end expiratory pressures.

Comparison of wind pressure coefficients between wind tunnel experiments and full-scale measurements using operational data from an urban high-rise building

Simulations during the design phase are performed to predict and evaluate the effect of natural ventilation of large buildings. Although the wind pressure coefficient has a significant impact on the prediction accuracy, comparisons between experimental and measured wind pressure coefficients are rare, especially for high-rise buildings in urban areas and under low-velocity outdoor winds commonly used for natural ventilation. This study compared wind pressure coefficients obtained from wind tunnel experiments with measured values to determine their accuracy for a high-rise building with 190 differential pressure transmitters installed on the walls for building monitoring and control. The building is located in an urban area, with several nearby buildings of comparable height. Long-term measurements were available, allowing for a sufficient number of samples even if they were limited to low-velocity outdoor winds. We processed the differential pressure data during building operation to obtain the wind pressure coefficient and compare it with that obtained from wind tunnel experiments. The results showed that the measured wind pressure coefficient can be obtained by appropriately processing the differential pressure data to exclude factors other than wind pressure, and that the measured wind pressure coefficient generally agrees well with the experimental value obtained by wind tunnel experiments.