End-expiratory Pressure Valve Research Articles

Comparison of the effectiveness of the helmet interface using flow meters versus the mechanical ventilator for non-invasive ventilation in patients with coronavirus disease 2019. Controlled and randomized clinical trial

IntroductionThis study aimed to compare the effectiveness of two methods for non-invasive mechanical ventilation in patients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) – using a helmet interface with a flow meter and positive end-expiratory pressure valve versus a traditional mechanical ventilator.Material and methodsWe conducted a single-center randomized clinical trial involving 100 adult SARS-CoV-2 patients in a specialized private hospital. Participants were randomly assigned to two groups: one using the helmet interface with a flow meter and positive end-expiratory pressure valve and the other employing conventional mechanical ventilation. Our study included participant selection, blood gas analysis, assessment of respiratory rate, peripheral oxygen saturation, modified Borg scale scores, and a visual analog scale.ResultsThe study showed no significant difference in intubation rates between the mechanical ventilation (54.3%) and helmet interface with flow meter and positive end-expiratory pressure valve (46.8%) groups (p = 0.37). Additionally, the helmet group had a shorter average duration of use (3.4 ±1.6 days) compared to the mechanical ventilation group (4.0 ±1.9 days). The helmet group also had a shorter average hospitalization duration (15.9 ±7.9 days) compared to the mechanical ventilation group (17.1 ±9.5 days).ConclusionsThis single-center randomized clinical trial found no statistically significant differences between the two methods of non-invasive ventilation. Implications for clinical practice: using the helmet interface with the flow meter and positive end-expiratory pressure valve can simplify device installation, potentially reducing the need for intubation, making it a valuable tool for nurses and physiotherapists in daily clinical practice.

Comparison of Efficacy of Pressure Controlled vs. Traditional Manual Mask Ventilation for Newborn Resuscitation - A Simulation-Based Pilot Randomized Control Trial.

To determine efficacy of non-invasive positive pressure face mask ventilation using a ventilator device (NIPPmV) for achieving early effective ventilation compared to that by self-inflating bag (SIB) or T- piece resuscitator (TPR). The authors video recorded 33 trained resuscitators using NIPPmV (provided using ventilator device), SIB [a 500ml silicone SIB without a positive end expiratory pressure (PEEP) valve] and a TPR. Using a continuous pressure recording system and a neonatal manikin, the authors evaluated the efficacy of the ventilation to achieve early effective ventilation during 30s of ventilation. The primary outcome was time to achieve effective chest rise. Secondary outcomes were peak inspiratory pressure (PIP), ventilation rate and the need to perform ventilation corrective steps during positive pressure ventilation (PPV) among the devices. Total 99 videos were recorded. The time(s) taken to achieve the first chest rise was significantly lesser in NIPPmV group compared to SIB and TPR (3.0 ± 1.7 vs. 3.7 ± 1.9 vs. 7.5 ± 5.4, respectively, p <0.001). The mean PIPdelivered by NIPPmV compared to SIB & TPR(19.8 ± 1.6 vs. 35.6 ± 7.4 vs. 17.8 ± 2.0cm H20 respectively; p <0.001) was more accurate with preset PIP. Ventilation, in terms of breath rate, was observed to be controlled more accurately with NIPPmV compared to SIB & TPR(50 vs. 42 vs. 33 per min respectively;p <0.001). The non-invasive positive pressure face mask ventilation using a ventilator (NIPPmV) resulted in achieving early, effective and consistent ventilation.

Helmet Continuous Positive Airway Pressure in the Emergency Department: A Practical Guide

Helmet continuous positive airway pressure is a simple, noninvasive respiratory support strategy to treat several forms of acute respiratory failure, such as cardiogenic pulmonary edema and pneumonia. Recently, it has been largely used worldwide during the COVID-19 pandemic. Given the increased use of helmet continuous positive airway pressure in the emergency department, we aimed to provide an updated practical guide for nurses and clinicians based on the latest available evidence. We focus our attention on how to set the respiratory circuit. Moreover, we discuss the interactions between flow generators, filters, and positive end-expiratory pressure valves and the consequences regarding the delivered gas flow, fraction of inspired oxygen, positive end-expiratory pressure, and noise level.

Effect of Proximal Oxygen Adding to a Bag Valve Mask with a Mechanical Filter in Healthy Volunteers: A Randomized Crossover Trial

Background: Preoxygenation using a bag valve mask (BVM) with a filter is recommended to reduce the risk of viral transmission. Preoxygenation in hypoxaemic patients may require a positive end-expiratory pressure (PEEP) valve. Applying a filter to a BVM with or without a PEEP valve can increase resistance and work of breathing. Objective: To evaluate the efficacy of proximal oxygen added to BVM with mechanical filter in healthy volunteers. Materials and Methods: The present study was a crossover trial that randomized 48 volunteers to receive four preoxygenation techniques: BVM with a filter as group F, BVM with a filter and proximal oxygen as group FO, BVM with a filter and PEEP valve as group FP, and BVM with a filter, PEEP valve, and proximal oxygen as group FPO. Fraction of expired oxygen (FEO₂) and continuous positive airway pressure (CPAP) were measured. Comfort was assessed using a numerical rating scale (NRS). The primary outcome was FEO₂ at five minutes. Results: Data from 46 volunteers were analyzed. Adding oxygen proximal to the filter in the FO group increased FEO₂ at five minutes by 7.07% (95% CI 4.87 to 9.26) and decreased the time to reach FEO₂ 90% by 301.74 seconds (95% CI 282.82 to 320.66) compared with the times in group F. Similarly, supplemental proximal oxygen including a PEEP valve increased FEO₂ at five minutes by 6.07% (95% CI 3.87 to 8.26) and decreased the time to reach FEO₂ 90% by 242.13 seconds (95% CI 223.21 to 261.05). CPAP was 2.27, 3.61, 11.65, and 13.14 mmHg in group F, FO, FP, and FPO, respectively. The NRS score was 6.51 and 6.07 in groups F and FO, and 3.15 and 3.70 in groups FP and FPO, respectively. Conclusion: Adding proximal oxygen to a BVM with a filter improved the efficacy of preoxygenation. Keywords: Bag valve mask; Efficacy of preoxygenation; Healthy volunteers; Mechanical filter; Positive end-expiratory pressure; Positive endexpiratory pressure valve

Positive Expiratory Pressure Oxygen Therapy for Respiratory Distress: A Single-arm Feasibility Trial.

Oxygen delivery devices with positive end-expiratory pressure (PEEP) valves have been described, but high inspiratory flows may lead to poor tolerance in tachypneic patients. Positive expiratory pressure oxygen therapy (PEP-OT) using an occlusive face mask, oxygen reservoir, and PEEP valve has not been evaluated in clinical settings. In a single-arm intervention trial, patients aged 19-55 years admitted with acute respiratory illness with oxygen support were enrolled. PEP-OT trial was given with PEEP of 5 and 7 cm of water over 45 minutes. Feasibility was assessed as uninterrupted completion of the PEP-OT trial. The effects of PEP-OT on cardiopulmonary physiology and adverse effects of therapy were recorded. Fifteen patients (6 males) were enrolled. Fourteen patients had pneumonia and one patient had pulmonary edema. Twelve patients (80%) completed the PEP-OT trial. There was significant improvement in respiratory rate (RR) and heart rate (HR) at the end of the 45-minute PEP-OT trial (p-values 0.048 and 0.003, respectively). There was a trend toward improved SpO2 and perceived dyspnea. None of the patients developed desaturation, shock, or air leaks. Positive expiratory pressure oxygen therapy is a feasible oxygen therapy in patients with acute hypoxia. Positive expiratory pressure oxygen therapy seems to be safe and has a positive impact on respiratory mechanics in parenchymal respiratory pathology. Dhochak N, Ray A, Soneja M, Wig N, Kabra SK, Lodha R. Positive Expiratory Pressure Oxygen Therapy for Respiratory Distress: A Single-arm Feasibility Trial. Indian J Crit Care Med 2022;26(11):1169-1174.

Modelling of a Positive End-Expiratory Pressure Valve with a Voice-coil Actuator

Abstract The positive end-expiratory pressure (PEEP) valve is important in the regulation of the pressure at the patient airways in devices for mechanical ventilation. The goal of this work is to derive a model that sufficiently captures the dynamics of the PEEP valve to be used for model-based control design. This paper describes the development of a model for common PEEP valve designs, thus allowing an adoption for different devices. A simplified first principle model with one mechanical degree of freedom is derived, under the assumption that the valve’s membrane behaves similar to a massspring- damper system. Following a grey-box model approach, physical parameters were lumped together and experimentally determined or identified from acquired data. Therefore, a valve test bench was developed to record various series of measurements. It was possible to determine a suitable flow factor which describes the correlation between flow, valve opening and upstream pressure. Additionally, a damping coefficient was estimated, with which the model achieves a good fit to the measured data at low dynamics and flows.

Cost-effective and power-efficient portable turbine-based emergency ventilator

Ventilators have always been common in medical scenarios but are very expensive to procure or develop. One of the main reasons for these is the components that are being used are expensive and require precise instrumentation, research, and development. This paper attempts to mitigate that problem by proposing a novel way to rapidly develop a portable ventilator that uses common 3D printing technology and off-the-shelf components. This turbine and valve-based ventilator feature most of the modes that are commonly used by healthcare professionals. A unique servo-based pressure release mechanism has been designed that makes the system around 36 times more efficient than solenoid-based systems. Reliability and efficiency have been increased further through the use of a novel positive end-expiratory pressure (PEEP) valve that does not contain any electromechanical component. Effective algorithms such as feed-forward and proportional–integral–derivative (PID) controllers were used alongside the unique ‘Sensor data filtration methodology’. The system also provides an interactive graphical user interface (GUI) via an android application that can be installed on any readily found tabs while the firmware manages the breathing detection algorithm using a flow meter and pressure sensor. This modular and portable ventilator also features a replaceable battery and holds the ability to run on solar power. This energy-efficient low-noise system can run for 5 to 6 h at a stretch without needing to be connected to the main’s supply.

High efficiency particulate air filters and heat & moisture exchanger filters increase positive end-expiratory pressure in helmet continuous positive airway pressure: A bench-top study

BackgroundHelmet continuous positive airway pressure (CPAP) has been widely used during the COVID-19 pandemic. Specific filters (i.e. High Efficiency Particulate Air filter: HEPA; Heat & Moisture Exchanger Filter: HMEF) were used to prevent Sars-CoV2 environmental dispersion and were connected to the CPAP helmet. However, HEPA and HMEF filters may act as resistors to expiratory gas flow and increase the levels of pressure within the hood. MethodsIn a bench-top study, we investigated the levels of airway pressure generated by different HEPA and HMEF filters connected to the CPAP helmet in the absence of a Positive End Expiratory Pressure (PEEP) valve and with two levels of PEEP (5 and 10 cmH2O). All steps were performed using 3 increasing levels of gas flow (60, 80, 100 L/min). ResultsThe use of 8 different commercially available filters significantly increased the pressure within the hood of the CPAP helmet with or without the use of PEEP valves. On average, the increase of pressure above the set PEEP ranged from 3 cmH2O to 10 cmH2O across gas flow rates of 60 to 100 L/min. The measure of airway pressure was highly correlated between the laboratory pressure transducer and the Helmet manometer. Bias with 95% Confidence Interval of Bias between the devices was 0.7 (-2.06; 0.66) cmH2O. ConclusionsThe use of HEPA and HMEF filters placed before the PEEP valve at the expiratory port of the CPAP helmet significantly increase the levels of airway pressure compared to the set level of PEEP. The manometer can detect accurately the airway pressure in the presence of HEPA and HMEF filters in the helmet CPAP and its use should considered.

Raising the awareness for insufficient oxygen delivery from self-inflating resuscitation bags lacking expiratory valve during preoxygenation

We recently read an interesting study which demonstrated that self-inflating resuscitation bag (SIRB) lacking expiratory valve has unreliable performance in oxygen delivery during spontaneous breathing mimicked by mechanical lung simulator. It was postulated that the absence of an expiratory valve and the resulting air entrainment via the exhaust port accounts for the poor oxygen delivery performance. The current disposable SIRB in-use in our institutions (Med-Rescuer Disposable BVM Resuscitator 4000, BLS Systems Limited, ON, Canada) has a duckbill valve but no expiratory valve. Safety concerns regarding its oxygen delivery performance during spontaneous breathing were raised, as this SIRB was commonly used to preoxygenate critically ill patient with potentially transmissible respiratory infection (e.g. COVID-19) before tracheal intubation. We therefore performed an experiment on this SIRB using one of us as a healthy volunteer. Our small experiment demonstrated that air entrainment could occur via the exhaust port and affect oxygen delivery performance. Our experiment also demonstrated that attaching a positive end-expiratory pressure (PEEP) valve to the exhaust port improves the oxygen delivery performance. The findings of this experiment were sent to the relevant department of our institutions for safety consideration.

Development of Lung Ventilator for the Treatment of COVID-19 Patient in Indonesia

Development program of local ventilator component, respiratory flow meter (RFM), respiratory blower fan (RBF), and positive end expiratory pressure (PEEP) valve are the main part of contribution to support medical team during COVID-19 virus outbreak that start on March, 2020 in Indonesia. In the COVID-19 pandemic era ventilator become necessary thing to treat Covid patient especially for worst cases patient. With increasing in people who infected by COVID-19 around the world and also in Indonesia, caused the demand of the ventilator system also increased significantly. In Indonesia many research institution and universities have been initiated to develop the emergency ventilator to support the increasing demand. Some companies in Indonesia initiate to develop the component of the lung ventilator to support other research institution therefore to minimize dependency from import product which is in the pandemic era the component such as flow meter and blower fan is difficult to get caused by stock limitation. In this paper we expose the process on development of three essential component part of the lung ventilator, i.e., respiratory flow meter (RFM), respiratory blower fan (RBF), and positive end expiratory pressure (PEEP) valve. The development of these components is using a standard design procedure and utilized with some design software for obtaining the optimum design result.

Devices for Administering Ventilation at Birth: A Systematic Review.

Positive pressure ventilation (PPV) is the most important intervention during neonatal resuscitation. To compare T-piece resuscitators (TPRs), self-inflating bags (SIBs), and flow-inflating bags for newborns receiving PPV during delivery room resuscitation. Medline, Embase, Cumulative Index to Nursing and Allied Health Literature, Cochrane Database of Systematic Reviews, and trial registries (inception to December 2020). Randomized, quasi-randomized, interrupted time series, controlled before-and-after, and cohort studies were included without language restrictions. Two researchers independently extracted data, assessed the risk of bias, and evaluated the certainty of evidence. The primary outcome was in-hospital mortality. When appropriate, data were pooled by using fixed-effect models. Meta-analysis of 4 randomized controlled trials (1247 patients) revealed no significant difference between TPR and SIB for in-hospital mortality (risk ratio 0.74; 95% confidence interval [CI] 0.40 to 1.34). Resuscitation with a TPR resulted in a shorter duration of PPV (mean difference -19.8 seconds; 95% CI -27.7 to -12.0 seconds) and lower risk of bronchopulmonary dysplasia (risk ratio 0.64; 95% CI 0.43 to 0.95; number needed to treat 32). No differences in clinically relevant outcomes were found in 2 randomized controlled trials used to compare SIBs with and without positive end-expiratory pressure valves. No studies used to evaluate flow-inflating bags were found. Certainty of evidence was very low or low for most outcomes. Resuscitation with a TPR compared with an SIB reduces the duration of PPV and risk of bronchopulmonary dysplasia. A strong recommendation cannot be made because of the low certainty of evidence. There is insufficient evidence to determine the effectiveness of positive end-expiratory pressure valves when used with SIBs.

Quantitative Assessment of Viral Dispersion Associated with Respiratory Support Devices in a Simulated Critical Care Environment.

Rationale: Patients with severe coronavirus disease (COVID-19) require supplemental oxygen and ventilatory support. It is unclear whether some respiratory support devices may increase the dispersion of infectious bioaerosols and thereby place healthcare workers at increased risk of infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).Objectives: To quantitatively compare viral dispersion from invasive and noninvasive respiratory support modalities.Methods: This study used a simulated ICU room with a breathing-patient simulator exhaling nebulized bacteriophages from the lower respiratory tract with various respiratory support modalities: invasive ventilation (through an endotracheal tube with an inflated cuff connected to a mechanical ventilator), helmet ventilation with a positive end-expiratory pressure (PEEP) valve, noninvasive bilevel positive-pressure ventilation, nonrebreather face masks, high-flow nasal oxygen (HFNO), and nasal prongs.Measurements and Main Results: Invasive ventilation and helmet ventilation with a PEEP valve were associated with the lowest bacteriophage concentrations in the air, and HFNO and nasal prongs were associated with the highest concentrations. At the intubating position, bacteriophage concentrations associated with HFNO (2.66 × 104 plaque-forming units [PFU]/L of air sampled), nasal prongs (1.60 × 104 PFU/L of air sampled), nonrebreather face masks (7.87 × 102 PFU/L of air sampled), and bilevel positive airway pressure (1.91 × 102 PFU/L of air sampled) were significantly higher than those associated with invasive ventilation (P < 0.05 for each). The difference between bacteriophage concentrations associated with helmet ventilation with a PEEP valve (4.29 × 10–1 PFU/L of air sampled) and bacteriophage concentrations associated with invasive ventilation was not statistically significant.Conclusions: These findings highlight the potential differential risk of dispersing virus among respiratory support devices and the importance of appropriate infection prevention and control practices and personal protective equipment for healthcare workers when caring for patients with transmissible respiratory viral infections such as SARS-CoV-2.

Manual hyperinflation in children.

ABSTRACTManual hyperinflation is used in neonatal and pediatric intensive care units to promote expiratory flow bias, but there is no consensus on the benefits of the technique. Thus, a review that presents supporting evidence is necessary. This study aims to review the literature on the manual hyperinflation maneuver in neonatal and pediatric intensive care units to analyze the evidence for this technique in terms of the forms of application (associated with other techniques or not), its safety, the performance of manual resuscitators and the influence of the physical therapist’s experience, in addition to evaluating the methodological quality of the identified articles. A search was performed in the following databases: Web of Science, ScienceDirect, PubMedⓇ, Scopus, CINAHL and SciELO. Two researchers independently selected the articles. Duplicate studies were assessed, evaluated by title and abstract and then read in full. The quality of the articles was analyzed using the PEDro scale. Six articles were included, two of which had high methodological quality. The main results provided information on the contribution of the positive end-expiratory pressure valve to increasing lung volumes and the use of chest compressions to optimize expiratory flow bias, the negative influence of operator experience on the increase in peak inspiratory flow, the performance of different manual resuscitators when used with the technique and the safety of application in terms of maintaining hemodynamic stability and increasing peripheral oxygen saturation. The available studies point to a positive effect of the manual hyperinflation maneuver in children who are admitted to intensive care units.Registration PROSPERO: CRD42018108056.

A Novel Low-Cost Ventilator for Use in a Worldwide Pandemic: The Portsmouth Ventilator.

We pursued development of a pneumatic-type ventilator. The basic design involves three electrically controlled solenoid valves, a pressure chamber, the patient breathing circuit, a positive end-expiratory pressure valve, and an electronics control system. Multiple safety elements were built into the design. The user-friendly interface allows simple control of ventilator settings. The ventilator delivers a hybrid form of pneumatic, assist-control ventilation, with predicted tidal volumes of 300-800 mL, positive end-expiratory pressure 0-20 cm H2O, and Fio2 21-100%. The ventilator was extensively tested with two separate high-fidelity lung simulators and a porcine in vivo model. Both lung simulators were able to simulate a variety of pathologic states, including obstructive lung disease and acute respiratory distress syndrome. The ventilator performed well across all simulated scenarios. Similarly, a porcine in vivo model was used to assess performance in live tissue, with a specific emphasis on gas exchange. The ventilator performed well in vivo and demonstrated noninferior ventilation and oxygenation when compared with the standard ventilator. The Portsmouth Ventilator was able to perform well across all simulated pathologies and in vivo. All components may be acquired by the public for a cost of approximately $250 U.S.D. Although this ventilator has limited functionality compared with modern ventilators, the simple design appears to be safe and would allow for rapid mass production if ventilator surge demand exceeded supply.

Inline Positive End-Expiratory Pressure Valves: The Essential Component of Individualized Split Ventilator Circuits.

Background:As resources are overwhelmed with the coronavirus disease 2019 pandemic, multiple approaches to produce individualized split-ventilator designs have emerged. These designs attempt to address the significant limitations and safety concerns of coventilation practices by allowing practitioners to adjust pressure settings for individual patients connected with specialized circuits to a single ventilator. The critical component in virtually all individualized circuit designs is the adjustable inline positive end-expiratory pressure valve.Methods:We reviewed the literature on the mechanics of inline positive end-expiratory pressure valve function, the implications and considerations for advanced application of inline positive end-expiratory pressure valves in individualized circuits, available methods of adapting commercial positive end-expiratory pressure valves in the resource-restricted setting, and major caveats of the use of inline positive end-expiratory pressure valves.Results and Conclusions:The function of adjustable inline positive end-expiratory pressure valves in advanced individualized ventilator circuits has not been described. Adjustable inline positive end-expiratory pressure valves are critical to individualized circuit reliability and patient safety when attempting to extend ventilator capacity in the setting of extreme ventilator shortages. Adjustable inline positive end-expiratory pressure valves provide a means to reduce delivered peak inspiratory pressure to an individual patient circuit, a method to increase positive end-expiratory pressure for an individual patient circuit, and act as an one-way valve to ensure unidirectional gas flow through the divided circuit. Adjustable inline positive end-expiratory pressure valves can be adapted from commercial valves or printed de novo when commercial options are unavailable. Noncommercial sourcing of ventilator components should only be considered in the setting of extreme ventilator shortages under the supervision of a knowledgeable anesthesiologist or intensivist.

A novel inline PEEP valve design for differential multi-ventilation

BackgroundVentilator sharing is one option to emergently increase ventilator capacity during a crisis but has been criticized for its inability to adjust for individual patient needs. Newer ventilator sharing designs use valves and restrictors to control pressures for each patient. A key component of these designs is an inline Positive End Expiratory Pressure (PEEP) Valve but these are not readily available. Creating an inline PEEP valve by converting a standard bag-valve-mask PEEP valve is possible with the addition of a 3D printed collar. MethodsThis was a feasibility study assessing the performance and safety of a method for converting a standard PEEP valve into an inline PEEP valve. A collar was designed and printed that covers the exhaust ports of the valve and returns exhaled gases to the ventilator. ResultsThe collar piece was simple to print and easily assembled with the standard PEEP valve. In bench testing it successfully created differential pressures in 2 simulated expiratory limbs without leaking to the atmosphere at pressures greater than 60 cm of H2O. ConclusionOur novel inline PEEP valve design shows promise as an option for building a safer ventilator sharing system.

Wearable positive end-expiratory pressure valve improves exercise performance

We tested a PEEP (4.2 cmH2O) mouthpiece (PMP) on maximal cycling performance in healthy adults. Experiment-1, PMP vs. non-PMP mouthpiece (CON) [n = 9 (5♂), Age = 30 ± 2 yr]; Experiment-2, PMP vs. no mouthpiece (NMP) [n = 10 (7♂), Age = 27 ± 1 yr]. At timepoint 1 in both experiments (mouthpiece condition randomized) subjects performed graded cycling testing (GXT) (Corival® cycle ergometer) to determine V˙O2peak (ml∗kg∗min−1), O2pulse (mlO2∗bt−1), GXT endurance time (GXT-T(s)), and V˙O2(ml∗kg∗min−1)-at-ventilatory-threshold (V˙O2 @VT). At timepoint 2 72 h later, subjects completed a ventilatory-threshold-endurance-ride [VTER(s)] timed to exhaustion at V˙O2 @VT power (W). One week later at timepoints 3 and 4 (time-of-day controlled), subjects repeated testing protocols under the alternate mouthpiece condition. Selected results (paired T-test, p<0.05): Experiment 1 PMP vs. CON, respectively: V˙O2peak ​= ​45.2 ​± ​2.4 vs. 42.4 ​± ​2.3 p<0.05; V˙O2@VT ​= ​33.7 ​± ​2.0 vs. 32.3 ​± ​1.6; GXT-TTE ​= ​521.7 ​± ​73.4 vs. 495.3 ​± ​72.8 (p<0.05); VTER ​= ​846.2 ​± ​166.0 vs. 743.1 ​± ​124.7; O2pulse ​= ​24.5 ​± ​1.4 vs. 23.1 ​± ​1.3 (p<0.05). Experiment 2 PMP vs. NMP, respectively: V˙O2peak ​= ​43.3 ​± ​1.6 vs. 41.7 ​± ​1.6 (p<0.05); V˙O2@VT ​= ​31.1 ​± ​1.2 vs. 29.1 ​± ​1.3 (p<0.05); GXT-TTE ​= ​511.7 ​± ​49.6 vs. 486.4 ​± ​49.6 (p<0.05); VTER 872.4 ​± ​134.0 vs. 792.9 ​± ​122.4; O2pulse ​= ​24.1 ​± ​0.9 vs. 23.4 ​± ​0.9 (p<0.05). Results demonstrate that the PMP conferred a significant performance benefit to cyclists completing high intensity cycling exercise.

Personalized Ventilation to Multiple Patients Using a Single Ventilator: Description and Proof of Concept.

To design and test a ventilator circuit that can be used for ventilation of two or more patients with a single ventilator, while allowing individualization of tidal volume, fractional concentration of oxygen, and positive end-expiratory pressure to each patient, irrespective of the other patient's respiratory system mechanics. Description and proof of concept studies. Respiratory therapy laboratory. Ventilation of mechanical test lungs. Following a previously advocated design, we used components readily available in our hospital to assemble two "bag-in-a-box" breathing circuits. Each patient circuit consisted of a flexible bag in a rigid container connected via one-way valve to a test lung, along with an inline positive end-expiratory pressure valve, connected to the ventilator's expiratory limb. Compressed gas fills the bags during "patient" exhalation. During inspiration, gas from the ventilator, in pressure control mode, enters the containers and displaces gas from the bags to the test lungs. We varied tidal volume, "respiratory system" compliance, and positive end-expiratory pressure in one lung and observed the effect on the tidal volume of the other. We were able to obtain different tidal volume, dynamic driving pressure, and positive end-expiratory pressure in the two lungs under widely different compliances in both lungs. Complete obstruction, or disconnection at the circuit connection to one test lung, had minimal effect (< 5% on average) on the ventilation to the co-ventilated lung. A secondary circuit "bag-in-the-box" system enables individualized ventilation of two lungs overcoming many of the concerns of ventilating more than one patient with a single ventilator.

Bag-Valve-Mask Ventilation After Induction for Intubation: PreVenting Hypoxemia?: July 2019 Annals of Emergency Medicine Journal Club

Bag-Valve-Mask Ventilation After Induction for Intubation: PreVenting Hypoxemia?: July 2019 Annals of Emergency Medicine Journal Club

Proposed safe apnea test using positive end-expiratory pressure valve and short-term blood gas analysis: Observational study.

The apnea test is an essential examination for the determination of brain death; however, hypotension, hypoxemia, and other complications during the apnea test can affect the stability of brain-dead patients, as well as organ function for recipients. Therefore, it is necessary to establish standard guidelines for apnea testing.The modified apnea test (MAT) comprises delivery of 100% oxygen through the endotracheal tube connected to manual resuscitator (Ambu bag) with the positive end-expiratory pressure (PEEP) valve after disconnection of the mechanical ventilator for maintenance of PEEP. Forty-nine instances of the conventional apnea test (CAT) were performed in 25 brain-dead patients; 77 instances of the MAT were performed in 39 brain-dead patients.The mean duration of the apnea test was 3.5 ± 1.4 minutes in the CAT group and 3.0 ± 1.2 minutes in the MAT group. There were no significant changes in PaCO2, PaO2, or pH between the CAT and MAT groups (P = .341, .593, and .503, respectively). In overweight patients (body mass index ≥ 23 kg/m2), MAT prevented dramatic reductions in PaO2 and SaO2 (P < .05 for both). In the patients who had hypoxic brain injury due to hanging, differences in PaO2 and SaO2 in the MAT group were significantly smaller than in the CAT group (P < .05).Although MAT, which was invented to maintain PEEP, was not efficient for all brain-dead patients, it could be helpful in selected patient groups, such as overweight patients or those who had hypoxic injury due to hanging. And clinicians should consider short-term apnea test to avoid unnecessarily prolonged hypoxemia.