Volume Ventilation Research Articles

Thermal storage performance analysis of building envelope based on big data sensor network

In order to understand the thermal storage performance analysis of building envelope, the author proposes a research on thermal storage performance analysis of building envelope based on Big data sensor network. The author first compares and analyzes the thermal storage performance parameter systems of different theoretical methods, and determines the key characterization parameters of thermal storage performance under different working conditions based on the analysis of the thermal storage process. Second, in order to compare and verify the measured and simulated indoor temperature of the building, two groups of buildings with identical exterior wall insulation performance and distinct thermal storage performance were chosen. Three distinct thermal storage levels of the building?s exterior walls were used to simulate and analyze the internal surface temperature, heat flux density, and building cooling and heating load. Summer night ventilation was used to investigate the effect of ventilation volume on building cooling loads. In the end, a provincial office building was chosen as the research subject. The structure comprises of two stories, one underground and two over the ground, with a north hub point of 180?. The investigation object is a two-story room. The trial results demonstrate that the deliberate outcomes are in great concurrence with the mimicked results. For the district of the region, under a similar protection execution of the nook structure, the inner surface temperature of the weighty construction outside wall is higher in winter, lower in summer, with a higher intensity load in winter and a lower cooling load in summer. The proper air changes each hour of building night ventilation is 16 ach, and the effect on the cooling heap of weighty structures is huge. Demonstrated the precision of the reproduction technique and model.

호흡운동을 동반한 몸통 안정화훈련이 폐기능에 미치는 영향

Purpose: The purpose of this study is to examine the effects of trunk stabilization training on pulmonary functions and respiratory muscle activity.
 Methods: All participants in this study were healthy and participated voluntarily. The participants were divided into 2 groups (10 people in the control group and 10 people in the trunk stabilization training group). The experimental group had trunk stabilization training with breathing exercises and the control group performed breathing exercises for 4 weeks. Pulmonary functions were assessed. Digital spirometry (Pony FX, COSMED Inc., Italy) and free EMG (Apsun, Inc., Italy) were used in order to determine the changes in the respiratory muscle. The SPSSWIN (version 21.0) package program was used for the statistical analysis.
 Results: The trunk stabilization training group (p<.05) had a significant difference in the forced expiratory volume in 1 second, forced vital capacity, inspiratory reserve volume, inspiratory capacity, and maximal voluntary ventilation prior to and after exercises. The control group, however, showed no change. No significant difference was seen in the change in respiratory muscular activity between the two groups.
 Conclusion: In order to improve pulmonary functions, application of trunk stabilization training can be a particularly effective intervention method.

Mechanical Ventilator Pressure and Volume Control Using Classifier Machine Learning Algorithm for Medical Care

Mechanical Ventilator Pressure and Volume Control Using Classifier Machine Learning Algorithm for Medical Care

A numerical study on the performance of a hybrid ventilation and power generation system

Ventilation, cooling and power are essential requirements of buildings. Integration of solar chimney, earth-air heat exchanger and photovoltaic panel forms a new hybridsystem, which is able to provide simultaneous ventilation, cooling capacity and electricity in an effective manner for buildings. The contribution of this study is to quantitatively identify the thermal and electrical performances of the hybrid system using a comprehensive validated numerical model. In addition, a parametric study was also performed to examine the effect of the number of EAHE pipe and solar collector on the performance of the hybrid system in order to further enhance the system performance. The results revealed that the peak daytime ventilation of the proposed hybrid system is reduced by 22.05 % compared to the ventilation system of solar chimney integrated with earth-air heat exchanger, and the outlet air temperature is reduced by 0.12 °C in average; the indoor temperatures for the hybrid and ventilation systems are slightly different. Moreover, the minimum electrical efficiency of hybrid system is 1.34 % higher than that for stand-alone photovoltaic system. Increasing the number of earth-air heat exchangers leads to more than 36.43 % increase in peak ventilation volume and 3.7 % improvement in electrical efficiency. In addition, increasing the quantity of solar chimney-photovoltaic modules can effectively increase the induced ventilation volume, and the outlet air temperature, but has slight effect on the temperature and electrical efficiency of photovoltaic panel. Therefore, the hybrid system not only can supply appropriate ventilation but also can generate electric power to buildings. The findings provide a preliminary guidance for optimizing design of the hybrid system.

Pressure-support compared with pressure-controlled ventilation mitigates lung and brain injury in experimental acute ischemic stroke in rats

BackgroundWe aimed to evaluate the pulmonary and cerebral effects of low-tidal volume ventilation in pressure-support (PSV) and pressure-controlled (PCV) modes at two PEEP levels in acute ischemic stroke (AIS).MethodsIn this randomized experimental study, AIS was induced by thermocoagulation in 30 healthy male Wistar rats. After 24 h, AIS animals were randomly assigned to PSV or PCV with VT = 6 mL/kg and PEEP = 2 cmH2O (PSV-PEEP2 and PCV-PEEP2) or PEEP = 5 cmH2O (PSV-PEEP5 and PCV-PEEP5) for 2 h. Lung mechanics, arterial blood gases, and echocardiography were evaluated before and after the experiment. Lungs and brain tissue were removed for histologic and molecular biology analysis. The primary endpoint was diffuse alveolar damage (DAD) score; secondary endpoints included brain histology and brain and lung molecular biology markers.ResultsIn lungs, DAD was lower with PSV-PEEP5 than PCV-PEEP5 (p < 0.001); interleukin (IL)-1β was lower with PSV-PEEP2 than PCV-PEEP2 (p = 0.016) and PSV-PEEP5 than PCV-PEEP5 (p = 0.046); zonula occludens-1 (ZO-1) was lower in PCV-PEEP5 than PCV-PEEP2 (p = 0.042). In brain, necrosis, hemorrhage, neuropil edema, and CD45 + microglia were lower in PSV than PCV animals at PEEP = 2 cmH2O (p = 0.036, p = 0.025, p = 0.018, p = 0.011, respectively) and PEEP = 5 cmH2O (p = 0.003, p = 0.003, p = 0.007, p = 0.003, respectively); IL-1β was lower while ZO-1 was higher in PSV-PEEP2 than PCV-PEEP2 (p = 0.009, p = 0.007, respectively), suggesting blood–brain barrier integrity. Claudin-5 was higher in PSV-PEEP2 than PSV-PEEP5 (p = 0.036).ConclusionIn experimental AIS, PSV compared with PCV reduced lung and brain injury. Lung ZO-1 reduced in PCV with PEEP = 2 versus PEEP = 5 cmH2O, while brain claudin-5 increased in PSV with PEEP = 2 versus PEEP = 5 cmH2O.

Electrical Impedance Tomography during Abdominal Laparoscopic Surgery: A Physiological Pilot Study

Background: Both general anesthesia and pneumoperitoneum insufflation during abdominal laparoscopic surgery can lead to atelectasis and impairment in oxygenation. Setting an appropriate level of external PEEP could reduce the occurrence of atelectasis and induce an improvement in gas exchange. However, in clinical practice, it is common to use a fixed PEEP level (i.e., 5 cmH2O), irrespective of the dynamic respiratory mechanics. We hypothesized setting a PEEP level guided by EIT in order to obtain an improvement in oxygenation and respiratory system compliance in lung-healthy patients than can benefit a personalized approach. Methods: Twelve consecutive patients scheduled for abdominal laparoscopic surgery were enrolled in this prospective study. The EIT Timpel Enlight 1800 was applied to each patient and a dedicated pneumotachograph and a spirometer flow sensor, integrated with EIT, constantly recorded respiratory mechanics. Gas exchange, respiratory mechanics and hemodynamics were recorded at five time points: T0, baseline; T1, after induction; T2, after pneumoperitoneum insufflation; T3, after a recruitment maneuver; and T4, at the end of surgery after desufflation. Results: A titrated mean PEEP of 8 cmH2O applied after a recruitment maneuver was successfully associated with the “best” compliance (58.4 ± 5.43 mL/cmH2O), with a low percentage of collapse (10%), an acceptable level of hyperdistention (0.02%). Pneumoperitoneum insufflation worsened respiratory system compliance, plateau pressure, and driving pressure, which significantly improved after the application of the recruitment maneuver and appropriate PEEP. PaO2 increased from 78.1 ± 9.49 mmHg at T0 to 188 ± 66.7 mmHg at T4 (p &lt; 0.01). Other respiratory parameters remained stable after abdominal desufflation. Hemodynamic parameters remained unchanged throughout the study. Conclusions: EIT, used as a non-invasive intra-operative monitor, enables the rapid assessment of lung volume and regional ventilation changes in patients undergoing laparoscopic surgery and helps to identify the “optimal” PEEP level in the operating theatre, improving ventilation strategies.

Fourteen-day E-Cigarette Exposure Disrupts Ventilation Patterns and Serum IL-1B Levels in Adolescent Rats

E-cigarettes are devices used to deliver vaporized liquids often containing nicotine and other chemicals. The purpose of this study was to investigate the effects of 14 days of e-cigarette vapor exposure in adolescent rats on lung function and inflammatory cytokine expression. Seventeen male long-evans rats were assigned to vape or air groups. The animals were exposed to either air or 5% nicotine vapor using a whole-body exposure chamber, once a day for ten minutes for fourteen consecutive days. Ventilation recordings were completed on day 0 (before exposure) and day 15 (after exposure) using unrestrained whole-body plethysmography. Both lung tissue and blood was collected for molecular assays. Baseline and post-exposure ventilation data were compared between air and vape groups across three different parameters: frequency, tidal volume, and minute ventilation. These parameters were compared resulting in three distinct 2x2 (time x treatment) Mixed Model ANOVAs. Between baseline and post-treatment measurements there was a significant decrease in values in minute ventilation (p=0.0312) and tidal volume (p=0.0031). Between treatment groups there was a significant difference in minute ventilation (p=0.0128) and frequency (p=0042). There were also significant alterations to the presence of IL-1B in the serum (p=0.0003), but not lung tissue (p=0.6525). In conclusion, following two weeks of e-cigarette vapor exposure, ventilation patterns were altered in the vapor exposed animals which decreased in tidal volume and minute ventilation suggesting possible impairment of lung function and e-cigarette exposure modified the expression of pro-inflammatory cytokine, IL-1B.

Ultra-low tidal volume ventilation during cardiopulmonary resuscitation shows no mitigating effect on pulmonary end-organ damage compared to standard ventilation: insights from a porcine model

ObjectiveThis study aimed to determine whether ultra-low tidal volume ventilation (ULTVV) applied during cardiopulmonary resuscitation (CPR) compared with standard ventilation (intermittent positive pressure ventilation, IPPV) can reduce pulmonary end-organ damage in the post-resuscitation period.MethodsA prospective, randomized trial was conducted using a porcine model (n = 45). The animals were divided into three groups: IPPV, ULTVV, and a sham control group. Juvenile male pigs underwent CPR after inducing ventricular fibrillation and received the designated ventilation intervention [IPPV: tidal volume 6–8 ml per kilogram body weight (ml/kg BW), respiratory rate 10/min, FiO2 1.0; ULTVV: tidal volume 2–3 ml/kg BW, respiratory rate 50/min, FiO2 1.0]. A 20-h observation period followed if return of spontaneous circulation was achieved. Histopathological examination using the diffuse alveolar damage scoring system was performed on postmortem lung tissue samples. Arterial and venous blood gas analyses and ventilation/perfusion measurements via multiple inert gas elimination technique (MIGET) were repeatedly recorded during the experiment.ResultsOut of the 45 experiments conducted, 28 animals were excluded based on predefined criteria. Histopathological analysis showed no significant differences in lung damage between the ULTVV and IPPV groups. ULTVV demonstrated adequate oxygenation and decarboxylation. MIGET measurements during and after resuscitation revealed no significant differences between the intervention groups.ConclusionIn the short-term follow-up phase, ULTVV demonstrated similar histopathological changes and functional pulmonary parameters compared to standard ventilation. Further research is needed to investigate the long-term effects and clinical implications of ULTVV in resuscitation settings.

Research on Intelligent Control of Regional Air Volume Based on Machine Learning

To address the challenge of intelligently controlling air volume in regions affected by the frequent fluctuations in underground ventilation networks, a remote intelligent air regulation method based on machine learning was presented. This method encompasses three core components: local fan frequency conversion regulation, associated branch air resistance regulation, and a comprehensive integration of both. Leveraging foundational mine ventilation theory, the principles behind branch sensitivity air regulation were dissected. By applying these principles, the key performance indicators crucial for the regulation of air volume within the ventilation system were identified. Subsequently, an intelligent model for regional air volume control was constructed. To validate the approach, an experimental platform for intelligent air volume control was established, guided by geometric, dynamic, and kinematic similarity criteria. Then, the experimental methodologies for simulating various ventilation scenarios were discussed, the data acquisition techniques were introduced, and the obtained results were analyzed. Employing machine learning techniques, we utilized five distinct algorithms to predict the operational parameters of targeted air volume ventilation equipment. It enabled precise and efficient control of air volume within the region. The results indicated that the least squares support vector machine (LS-SVM) stood out by delivering high-precision predictions of target air volume ventilation equipment parameters, all while maintaining a relatively short calculation time. This swift generation of feedback data and corresponding air volume control strategies will contribute to the precise management of air volume in the area. This work served as a valuable theoretical and practical guide for intelligent mining ventilation control.

Study on ambient temperature and humidity in the construction tunnel under the influence of ventilation and hot water gushing

The influx of hot water will intensify the detrimental effects of heat and humidity during the excavation of high geothermal tunnels. The spatiotemporal evolution of the ambient temperature-humidity field in the construction tunnel under the coupling action of ventilation and hot water is critical. Based on the theory of heat and mass transfer, a numerical model was developed to simulate the temperature and humidity conditions within a construction tunnel. The model considers the coupling effects of heat and moisture between airflow, hot water, and the surrounding rock. The distribution of temperature and humidity in the tunnel was analyzed, and the study investigated the influence mechanisms of ventilation volume (Va) and water gushing conditions on the ambient temperature and humidity in the construction tunnel. The main conclusions include: (1) During tunnel construction, the airflow temperature (Ta) and relative humidity (RH) varied as follows: heating and humidifying, constant humidity heating, and constant humidity cooling. (2) Altering the water temperature (Tw) will affect the distribution pattern of RH from the working face to the tunnel portal. Similarly, modifying the length of the ditch without the cover plate (Lc) will impact the distribution trend of Ta and RH. (3) When the Va affects the RH mainly through the airflow velocity rather than the evaporation coefficient, the linearity between the Va and RH is weak. Water volume and Tw both impact the humidity distribution by altering the amount of heat needed for evaporation. (4) Given the significance of the impact of individual factors on the temperature and humidity, it is advised that the Ta and RH be regulated by increasing the Va and decreasing the Lc, respectively. The research can give direction for temperature and humidity control in a tunnel where hot water gushes during construction.

Mechanical ventilation practices in Asian intensive care units: A multicenter cross-sectional study

PurposeThis study investigated current practices of mechanical ventilation in Asian intensive care units, focusing on tidal volume, plateau pressure, and positive end-expiratory pressure (PEEP). Materials and methodsIn this multicenter cross-sectional study, data on mechanical ventilation and clinical outcomes were collected. Predictors of mortality were analyzed by univariate and multivariable logistic regression. A scoring system was generated to predict 28-day mortality. ResultsA total of 1408 patients were enrolled. In 138 patients with acute respiratory distress syndrome (ARDS), 65.9% were on a tidal volume ≤ 8 ml/kg predicted body weight (PBW), and 71.3% were on sufficient PEEP. In 1270 patients without ARDS, 88.8% were on a tidal volume ≤ 10 ml/kg PBW. A plateau pressure < 30 cmH2O was measured in 92.2% of patients. Mortality rates increased from 13% to 74% as the generated predictive score increased from 5 to ≥8.5. Income classification, age, SOFA score, PaO2/FiO2 ratio, plateau pressure, number of vasopressors, and steroid use were associated with mortality. ConclusionsIn Asia, low tidal volume ventilation and sufficient PEEP were underused in patients with ARDS. The majority of patients without ARDS were on intermediate tidal volumes. Country income, age, and severity of illness were associated with mortality.

Abstract 309: The Hiccup Method for BLS HPCPR for Pediatric Cardiac Arrest: Description of Technique and Quality Metrics in Simulated Pediatric Out of Hospital Cardiac Arrest (OHCA)

Key principles of high-performance CPR (HPCPR) include optimizing rate and depth of chest compressions, and minimizing pauses. Maryland EMS sought compromise to translate existing adult HPCPR protocol to accommodate AHA 15:2 compression: ventilation ratio pediatric recommendations. The resulting “Maryland Hiccup” method of HPCPR delivers 1 ventilation on each upstrokes after compressions 14 and 15, resulting in nearly continuous compressions. We sought to determine how the Maryland Hiccup (MH) style of CPR compares to the standard AHA 15:2 (AHA) style in simulated pediatric CPR performed by EMS clinicians. Methods: Teams of 2-person EMS providers utilized a child -size medium fidelity manikin to perform four-minute cycles of HPCPR. Teams were randomly assigned 2 cycles in either MH or AHA style, then crossed over to the other style. HPCPR performance metrics were compared: compression fraction, no flow time, rate, depth, and ventilation rate and volume using student’s t-test. Results: Thirty-eight clinicians (22 BLS, 16 ALS) participated. Both compression fraction (80% with AHA vs 98% with MH, p &lt; .001) and no flow time (2.79 seconds with AHA vs 0.16 seconds with MH, p&lt;.001) were improved with MH technique. Overall compressions were deeper than the recommended 2 inches or 5 cm, with AHA than MH (63mm vs 60mm respectively, p=0.01, Table 1). No differences were noted in compression rate, ventilation rate or ventilation volume. Conclusions: The Maryland Hiccup style of HPCPR with synchronized ventilations interspersed with chest compressions significantly improves CPR quality metrics in simulated pediatric CPR by EMS clinicians. While the CCF was superior with the MH method (98%), the chest compression depth was shallower than the AHA method by 3mm. How this translates to changes in actual patient outcomes has yet to be determined. Further study is warranted to explore physiologic benefits and patient outcome.

Study on dynamic control system of tunnel variable air volume ventilation based on first-order delay and predictive compensation control model

Using a variable air volume ventilation system is an efficient way to save energy in the tunnel. To address the issues of low control parameter accuracy and high operating energy consumption, the transient flow field and ventilation resistance characteristics were analyzed using conservation equations, and the first-order delay mathematical model of tunnel ventilation control was established by taking tunnel and jet fan parameters into account. The airflow dynamic control model's related parameters and transfer function were also solved. The overshoot, steady value, and adjustment time of the control system were evaluated using simulation and experiment. In full-scale experiments, the required wind speed was converted into the frequency of the jet fans to achieve variable air volume ventilation control. The results show that the variable air volume ventilation control system has the characteristics of nonlinear, and the first-order delay time transfer function is related to the 1/2-th power of ventilation resistance and pressure. The control system performs well, and the response parameters are all within the error range. Moreover, the discussion results of the comparative tests also illustrated that the purpose of dynamic wind speed adjustment could be achieved through frequency conversion control.

The first direct measurements of ventilatory flow and oxygen utilization after exhaustive exercise and voluntary feeding in a teleost fish, Oncorhynchus mykiss.

A new "less invasive" device incorporating an ultrasonic flow probe and a divided chamber, but no stitching of membranes to the fish, was employed to make the first direct measurements of ventilatory flow rate (V̇w) and % O2 utilization (%U) in juvenile rainbow trout (37g, 8ºC) after exhaustive exercise (10-min chasing) and voluntary feeding (2.72% body mass ration). Under resting conditions, the allometrically scaled V̇w (300mlkg-1min-1 for a 37-g trout = 147mlkg-1min-1 for a 236-g trout exhibiting the same mass-specific O2 consumption rate, ṀO2) and the convection requirement for O2 (CR = 4.13 L mmol-1) were considerably lower, and the %U (67%) was considerably higher than in previous studies using surgically attached masks or the Fick principle. After exhaustive exercise, V̇w and ṀO2 approximately doubled whereas frequency (fr) and %U barely changed, so increased ventilatory stroke volume (Vsv) was the most important contributor to increased ṀO2. CR declined slightly. Values gradually returned to control conditions after 2-3h. After voluntary feeding, short-term increases in V̇w, Vsv and ṀO2 were comparable to those after exercise, and fr again did not change. However, %U increased so CR declined even more. The initial peaks in V̇w, Vsv and ṀO2, similar to those after exercise, were likely influenced by the excitement and exercise component of voluntary feeding. However, in contrast to post-exercise fish, post-prandial fish exhibited second peaks in these same parameters at 1-3h after feeding, and %U increased further, surpassing 85%, reflecting the true "specific dynamic action" response. We conclude that respiration in trout is much more efficient than previously believed.

P010 Delivery of volume assured pressure support (VAPS) through tracheostomy in paediatric patients

Abstract INTRODUCTION Volume assured pressure support (VAPS) allows the ventilator to deliver a constant pre-set tidal volume or alveolar ventilation by automatically adjusting the inspiratory pressures within a set range, providing targeted pressure support. Data on its use in children are limited. We describe a series of four children effectively and safely ventilated using VAPS mode through tracheostomy. METHODS Retrospective review of patient notes. PROGRESS TO DATE Four paediatric patients were identified in our cohort who were successfully and safely ventilated using the VAPS mode through tracheostomy. The patients were between 6-14 years of age inclusive, with four differing underlying disease processes – Prader-Willi syndrome, congenital central hypoventilation syndrome, Guillain-Barré syndrome and Moebius-type syndrome. INTENDED OUTCOME AND IMPACT Whilst there have been previous paediatric case reports and case series which have demonstrated efficacy of VAPS mode used non-invasively, the use of VAPS mode to provide effective and safe ventilation through tracheostomy in children has been described in only one recent case series. The advantages of its use over conventional bilevel positive airway pressure support include its ability to compensate for changes in tidal volume, which can occur with changes in lung compliance and during different stages of sleep. This case series highlights safe and effective use of VAPS mode in children with tracheostomy.

Airway Pressure Release Ventilation in COVID-19-Associated Acute Respiratory Distress Syndrome-A Multicenter Propensity Score-Matched Analysis.

Background: There are limited and partially contradictory data on the effects of airway pressure release ventilation (APRV) in COVID-19-associated acute respiratory distress syndrome (CARDS). Therefore, we analyzed the clinical outcome, complications, and longitudinal course of ventilation parameters and laboratory values in patients with CARDS, who were mechanically ventilated using APRV. Methods: Respective data from 4 intensive care units (ICUs) were collected and compared to a matched cohort of patients receiving conventional low tidal volume ventilation (LTV). Propensity score matching was performed based on age, sex, blood gas analysis, and APACHE II score at admission, as well as the implementation of prone positioning. Findings: Forty patients with CARDS, who were mechanically ventilated using APRV, and 40 patients receiving LTV were matched. No significant differences were detected for tidal volumes per predicted body weight, peak pressure values, and blood gas analyses on admission, 6 h post admission as well as on day 3 and day 7. Regarding ICU survival, no significant difference was identified between APRV patients (40%) and LTV patients (42%). Median duration of mechanical ventilation and duration of ICU treatment were comparable in both groups. Similar complication rates with respect to ventilator-associated pneumonia, septic shock, thromboembolic events, barotrauma, as well as the necessity for hemodialysis were detected for both groups. Clinical characteristics that were associated with increased mortality in a Cox proportional hazards regression analysis included age (hazard ratio [HR] 1.08, 95% confidence interval [CI] 1.04-1.1; P < .001), severe acute respiratory distress syndrome (HR 2.62, 95% CI 1.02-6.7; P = .046) and the occurrence of septic shock (HR 17.18, 95% CI 2.06-143.2; P = .009), but not the ventilation mode. Interpretation: Intensive care unit survival, duration of mechanical ventilation, and ICU treatment as well as ventilation-associated complication rates were equivalent using APRV compared to conventional LTV in patients with CARDS.

A Single 10-Minute E-cigarette Vapor Exposure Reduces Tidal Volume and Minute Ventilation in Normoxia and Normobaric Hypoxia in Adult Rats.

The present study investigated the effects of a single 10-minute exposure to e-cigarette vapor on ventilation in adult male Long-Evans rats. Ventilation was recorded using awake, unrestrained whole-body plethysmography. Baseline recordings were taken the day before full-body exposure to either room air (n = 9; air control group) or e-cigarette vapor (n = 9; treatment group). Post-exposure recordings were taken immediately after the 10-minute room air or vapor exposure. As part of the ventilation protocol, in addition to recording the subject's ventilation in room air, the subjects were also exposed to 10% oxygen (balanced with nitrogen) to assess the effects of e-cigarette vapor on an increased drive to breathe. Ventilation data were analyzed using a 2x2x2 mixed-model ANOVA measuring treatment (vape vs. air) x time (baseline vs. post-treatment) x condition (normoxia vs. hypoxia) for breathing frequency, tidal volume, and minute ventilation. Breathing frequency increased in both treatment groups (air and vape) with exposure to normobaric hypoxia (p < 0.001), with no effect of time (baseline vs. post-treatment) for either group. Tidal volume increased in both treatment groups (air and vape) with exposure to normobaric hypoxia (p < 0.001), and an effect of time (baseline vs. post-treatment) was observed (p = 0.010) for the vape group. Minute ventilation increased in both treatment groups (air and vape) with exposure to normobaric hypoxia (p < 0.001), and an effect of time (baseline vs. post-treatment) was observed (p < 0.001) for the vape group. In conclusion, immediately following a single 10-minute e-cigarette vapor exposure, both tidal volume and minute ventilation were reduced during normoxia and normobaric hypoxia, indicating a decrease in ventilation after a single 10-minute e-cigarette vapor exposure. Furthermore, this exposure also blunted the physiological response to acute hypoxia exposure. Subjects in the vape group, while breathing more rapidly as expected, experienced shallower breathing than the air group during hypoxia. The findings in this study confirm that vaping could result in reduced lung function.

Comparison of ventilatory and oxygen consumption measurements of yearling Thoroughbred colts and fillies exercising unridden on an all-weather track

Sex effects on ventilatory and oxygen consumption (V̇O2) measurements during exercise have been identified in humans. This study’s aim was to evaluate the hypothesis that there are sex effects on ventilatory and V̇O2 measurements in exercising, untrained yearling Thoroughbreds (Tb). Forty-one Tbs (16 colts, 25 fillies; 19.8 ± 1.4 months old) were recruited. Physiological, ventilatory and exercise data were gathered from horses exercising unridden at high intensity on an all-weather track from a global positioning-heart rate unit and a portable ergospirometry system. Data were analysed with an unpaired Student’s t-test and the Benjamini-Hochberg correction for multiple testing (P ≤ 0.05 significant). Mean bodyweight (BW, P = 0.002) and wither height (P = 0.04) were greater for colts than fillies. There were no differences in physiological and exercise data and absolute peak V̇O2 between groups. However, fillies had a higher mass specific peak V̇O2 (P = 0.03) than colts (121.5 ± 21.6 mL/kg.min vs. 111.9 ± 27.4 mL/kg.min). The peak breathing frequency was greater for fillies (P < 0.001) while the peak inspiratory (P < 0.001) and expiratory air flow (P < 0.001), peak expiratory tidal volume (VTE; P < 0.001) and peak minute ventilation (V̇E; P = 0.01) were greater for colts; there were no differences for peak VTE and V̇E when adjusted for BW. Differences in BW explain the differences in mass specific peak V̇O2 between groups. Given their morphological differences, it is likely that lung volumes and airway diameters are smaller for fillies, resulting in greater resistance and lower air flows and volumes. Further research is required to investigate the ventilatory differences and how they may change with maturation and impact performance.

Effect of bubble morphology and behavior on power consumption in non-Newtonian fluids’ aeration process

Due to a prolonged operation time and low mass transfer efficiency, the primary challenge in the aeration process of non-Newtonian fluids is the high energy consumption, which is closely related to the form and rate of impeller, ventilation, rheological properties and bubble morphology in the reactor. In this perspective, through optimal computational fluid dynamics models and experiments, the relationship between power consumption, volumetric mass transfer rate (kLa) and initial bubble size (d0) was constructed to establish an efficient operation mode for the aeration process of non-Newtonian fluids. It was found that reducing the d0 could significantly increase the oxygen mass transfer rate, resulting in an obvious decrease in the ventilation volume and impeller speed. When d0 was regulated within 2–5 mm, an optimal kLa could be achieved, and 21% of power consumption could be saved, compared to the case of bubbles with a diameter of 10 mm.

Low Tidal Volume Ventilation Is Poorly Implemented for Patients in North American and United Kingdom ICUs Using Electronic Health Records

Low tidal volume ventilation (LTVV;< 8mL/kg predicted body weight [PBW]) is a well-established standard of care associated with improved outcomes. This study used data collated in multicenter electronic health record ICU databases from the United Kingdom and the United States to analyze the use of LTVV in routine clinical practice. What factors are associated with adherence to LTVV in the United Kingdom and North America? This was a retrospective, multicenter study across the United Kingdom and United States of patients who were mechanically ventilated. Factors associated with adherence to LTVV were assessed in all patients in both databases who were mechanically ventilated for > 48 h. We observed trends over time and investigated whether LTVV was associated with patient outcomes (30-day mortality and duration of ventilation) and identified strategies to improve adherence to LTVV. A total of 5,466 (Critical Care Health Informatics Collaborative [CCHIC]) and 7,384 electronic ICU collaborative research database [eICU-CRD] patients were ventilated for > 48h and had data of suitable quality for analysis. The median tidal volume (VT) values were 7.48mL/kg PBW (CCHIC) and 7.91mL/kg PBW (eICU-CRD). The patients at highest risk of not receiving LTVV were shorter than 160cm (CCHIC) and 165cm (eICU-CRD). Those with BMI > 30kg/m2 (CCHIC OR, 1.9 [95%CI, 1.7-2.13]; eICU-CRD OR, 1.61 [95%CI, 1.49-1.75]) and female patients (CCHIC OR, 2.39 [95%CI, 2.16-2.65]; eICU-CRD OR, 2.29 [95%CI, 2.26-2.31]) were at increased risk of having median VT > 8mL/kg PBW. Patients with median VT< 8mL/kg PBW had decreased 30-day mortality in the CCHIC database (CCHIC cause-specific hazard ratio, 0.86 [95%CI, 0.76-0.97]; eICU-CRD cause-specific hazard ratio, 0.9 [95%CI, 0.86-1.00]). There was a significant reduction in VT over time in the CCHIC database. There has been limited implementation of LTVV in routine clinical practice in the United Kingdom and the United States. VT > 8mL/kg PBW was associated with worse patient outcomes.