Safety Of Ventilation Research Articles

Development on risk assessment model of urban ventilation based on COVID-19 pollution——A case study of an innovation base in Chongqing

Numbers of constructions have emerged due to the continuous urbanization process and the diversity of building clusters. Meanwhile, frequent global epidemics, such as COVID-19, have raised higher requirements for efficient urban ventilation. Traditional building design is insufficient to quantitatively consider the rationality of urban ventilation and corresponding risk assessments. This study carries out urban safety ventilation research and provides risk assessment models by using simulation and mathematical induction based on on-site measurement data, to realize accurate evaluation of disturbance of building clusters in urban environment, taking an Innovation Base in Chongqing as an example. The Amplification Coefficients on Urban Disturbance (ACUD) of the Innovation Base are respectively σ1 = 0.047 representing safe evacuation distance for ventilation of new buildings downstream, σ2 = 0.403 representing origin airflow disturbance retreat of new buildings, σ3 = 1.261 representing the control range of skyline design, and σ4 = 4.381 representing urban canopy ventilation boundary. The Comprehensive Risk Coefficient (CRC) of the Innovation Base in the horizontal & vertical direction of CRCh = 17.88 and CRCv = 102.97 is obtained indicating the infection risk of residents in the vertical direction is 5.76 times greater than that in the horizontal direction. The Comprehensive Pollution Disturbance (CPD) is 1.70692*10−19 kg/m3 which can be regarded as the quantitative risk assessment index of the Innovation Base under large public health safety events. This study contributes to effective support of architectural and urban design facing safe ventilation, providing theoretical support for the risk assessments, the resident control and anti-epidemic policies for both governments and residents during the worldwide epidemic situation.

Respiratory Therapists’ Knowledge and Attitudes on Safe Ventilator Management in Magnetic Resonance Imaging Units: A Cross-sectional Study

Abstract Background: Respiratory therapists (RTs) play a crucial role in managing ventilators in magnetic resonance imaging (MRI) units, where magnetic fields pose safety risks, emphasizing the need for comprehensive knowledge of MRI safety procedures to prevent patient harm. Aims: This study aimed to evaluate RTs’ knowledge of MRI systems and safety procedures to ensure the safe and effective management of ventilators within an MRI environment. Subjects and Methods: An exploratory cross-sectional study was conducted in Saudi Arabia. Questionnaires were distributed to RTs via various social media platforms, collecting data from multiple cities and hospitals. Data analysis was performed using the Statistical Package for the Social Sciences (SPSS), Version 22. Results: The study included 269 participants, with 37.9% of females and 62.1% of males. Regarding MRI safety knowledge, 48.0% of participants received training during orientation, while 20.4% received no training postgraduation. In addition, 69.5% lacked certification in MRI safety. Despite this, 88.1% reported no safety incidents, and 90.7% acknowledged the importance of communication with MRI teams. Significant relationships were found between MRI safety knowledge and variables such as age (P = 0.042), time since last learning (P = 0.0001), and the institution of the last qualification (P = 0.004). Conclusion: This study identifies significant gaps in MRI safety knowledge among RTs in Saudi Arabia, with 69.5% lacking formal certification. Despite these gaps, 88.1% reported no incidents. The findings underscore the need for structured training programs and continuous professional development to enhance MRI safety and improve patient care. Policymakers should mandate comprehensive MRI safety training to ensure consistent practices across health-care facilities.

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.

COSTS REDUCTION OF MAIN FANS OPERATION ACCORDING TO SAFETY VENTILATION IN MINES – A CASE STUDY

Considering the various hazards present in an underground mine, safe ventilation entails maintaining a certain airflow rate in the mining workings. The air velocity, airflow rate and air composition must be regulated in a ventilation network by operation of the main fans. On the other hand, ventilation costs must be minimized. Thus, the optimal solution is when the requisite safety features are fulfilled and the power output of the fans is at a minimal yet sufficient rate. In real-world mines, it is common to have airstreams interlinking subnets of the main fans. The current restructuring of the mining sector commonly involves the connection of different mines, which leads to an increase in the number of such cases. This article presents the results of research into ventilation networks containing these kind of airstreams and introduces a new method for reducing ventilation costs. The method is based on an algorithm which allows the determination of the resistance of a stopping, the head of the fans and the air quantity for which air distribution is optimal. As a result, the total power output of the fans is at the lowest level that yields a reduction in ventilation costs. The method was applied for two theoretical examples and a practical one which was taken from a real ventilation network. In the first example, fan power output was reduced by 17.252 kW, which gave an annual reduction of 188.909 MWh, and an annual electricity cost reduction of €27014. Therefore, optimization enabled a saving of approximately 14% of the costs. In the second example, power output was reduced by 106.152 kW, which produced an annual reduction of 1162.364 MWh, and an annual electricity cost reduction of €166218. In this case, optimization allowed a reduction in costs of approximately 40%. Considering both examples, the cost reductions did not affect the safe airflow rate. For the real-world mine, the annual savings were 2343 MWh, which corresponds to approximately €335000.

Standard precautions should include 'safe ventilation' to minimise far-afield airborne transmission in health and social care settings.

Standard precautions should include 'safe ventilation' to minimise far-afield airborne transmission in health and social care settings.

Treatment of cicatricial tracheal stenosis and tracheoesophageal fistula in patients with COVID-19 pneumonia

To describe treatment of cicatricial tracheal stenosis and tracheoesophageal fistula in patients with COVID-19 pneumonia. There were 91 patients with cicatricial tracheal stenosis for the period from August 2020 to April 2022 (21 months). Of these, 32 (35.2%) patients had cicatricial tracheal stenosis, tracheoesophageal fistula and previous coronavirus infection with severe acute respiratory syndrome. Incidence of iatrogenic tracheal injury following ventilation for viral pneumonia in the pandemic increased by 5 times compared to pneumonia of other genesis. Majority of patients had pneumonia CT grade 4 (12 patients) and grade 3 (8 patients). Other ones had pulmonary parenchyma lesion grade 2-3 or mixed viral-bacterial pneumonia. Isolated tracheoesophageal fistula without severe cicatricial stenosis of trachea or esophagus was diagnosed in 4 patients. In other 2 patients, tracheal stenosis was combined with tracheoesophageal fistula. Eight (25%) patients had tracheostomy at the first admission. This rate was almost half that of patients treated for cicatricial tracheal stenosis in pre-pandemic period. Respiratory distress syndrome occurred in 1-7 months after discharge from COVID hospital. All patients underwent surgery. In 7 patients, we preferred palliative treatment with dilation and stenting until complete rehabilitation. In 5 patients, stent was removed after 6-9 months and these ones underwent surgery. There were 3 tracheal resections with anastomosis, and 2 patients underwent tracheoplasty. Resection was performed in 3 patients due to impossible stenting. Postoperative course in these patients was standard and did not differ from that in patients without viral pneumonia. In case of tracheoesophageal fistula, palliative interventions rarely allowed isolation of trachea. Four patients underwent surgery through cervical approach. There were difficult surgeries in 2 patients with tracheoesophageal fistula and cicatricial tracheal stenosis. One of them underwent separation of fistula and tracheal resection via cervical approach at primary admission. In another patient with thoracic fistula, we initially attempted to insert occluder. However, open surgery was required later due to dislocation of device. Absolute number of patients with tracheal stenosis, tracheoesophageal fistula and previous COVID-19 has increased by several times compared to pre-pandemic period. This is due to greater number of patients requiring ventilation with risk of tracheal injury, non-compliance with preventive protocol for tracheal injury including anti-ischemic measures during mechanical ventilation. The last fact was exacerbated by involvement of allied physicians with insufficient experience of safe ventilation in the «red zone», immunodeficiency in these patients aggravating purulent-inflammatory process in tracheal wall. The number of patients with tracheostomy was 2 times less that was associated with peculiarity of mechanical ventilation in SARS-CoV-2. Indeed, tracheostomy was a poor prognostic sign and physicians tried to avoid this procedure. Incidence of tracheoesophageal fistula in these patients increased by 2 times compared to pre-pandemic period. In subacute period of COVID-associated pneumonia, palliative measures for cicatricial tracheal stenosis and tracheoesophageal fistula should be preferred. Radical treatment should be performed after 3-6 months. Absolute indication for circular tracheal resection with anastomosis is impossible tracheal stenting and ensuring safe breathing by endoscopic methods, as well as combination of cicatricial tracheal stenosis with tracheoesophageal fistula and resistant aspiration syndrome. Incidence of postoperative complications in patients with cicatricial tracheal stenosis and previous mechanical ventilation for COVID-19 pneumonia and patients in pre-pandemic period is similar.

Just-in-time in-situ simulation for high stakes success in viral haemorrhagic fever (VHF)

Success of just-in-time in-situ simulation to find new ways of working, test processes, and uncover latent error to promote patient and staff safety is well documented from the COVID-19 pandemic [1,2]. We used just-in-time simulation in a unique situation where imminent transfer of a critically unwell patient with VHF was required to our high-level isolation unit (HLIU). The Trexler isolator tent is custom made for treating high consequence infectious diseases (HCID), requires specific training. Staff provide care by ‘stepping’ into ‘suits’ in the plastic walls. Transfers into the tent are time-critical to reduce potential exposure risk to staff. This was the first time ever an intubated, ventilated patient was to be transferred into the tent. Simulation, Infectious Diseases, and Intensive Care teams collaborated within a few hours’ notice to simulate in-situ the mechanism of transferring a patient (using a Laerdal SimMan 3G) intubated and ventilated with multiple drug infusions running, headfirst from a transport trolley into the foot end of the isolator tent. This was repeated subsequently in several Plan-Do-Study-Act (PDSA) cycles to refine the process and reduce transfer time taken. There were multiple pauses as problems, latent threats, and potential failure points were identified, and time outs to discuss solutions. Transfer teams informally reported increased confidence being able to troubleshoot and rehearse the transfer process before patient arrival. Key learning related to leadership, communication, highlighting safety steps, and sharing mental models between teams such as airway management, significance during transfer and ergonomics of airway-trained personnel positioning in the tent. This was written up as a visual aid for the transfer team. Environmental latent threats found included safe ventilator mounting, IV pump management, emergency drug preparation, and allowed for enhanced consideration of the practicalities of caring for an intensive care patient in the HLIU tent. The actual transfer of the patient went smoothly and without incident. Further simulations were run during the patient care episode to rehearse and potential anticipate airway and ventilation management issues. Just-in-time in-situ simulation provided a valuable opportunity to rehearse a high-stakes, never done before activity, and facilitated identification of environmental latent threats before patient arrival. It created a shared mental model between different specialities of patient needs contributing towards an increased situational awareness and ability to forward plan and project, ultimately increasing patient and staff safety. 1. Guris RJ, Doshi A, Boyer DL, Good G, Gurnaney HG, Rosenblatt S, McGowan N, Widmeier K, Kishida M, Nadkarni V, Nishisaki A. Just-in-time simulation to guide workflow design for coronavirus disease 2019 difficult airway management. Pediatric Critical Care Medicine. 2020;21(8):e485. 2. Zucco L, Chen MJ, Levy N, Obeidat SS, Needham MJ, Hyatt A, Keane JR, Pollard RJ, Mitchell JD, Ramachandran SK. Just-in-Time In Situ Simulation Training as a Preparedness Measure for the Perioperative Care of COVID-19 Patients. Simulation in Healthcare: Journal of the Society for Simulation in Healthcare. 2022 Feb 10; Published Ahead of Print. doi: 10.1097/SIH.0000000000000635 We acknowledge the hard work and expertise of the Infectious diseases and Intensive care medical and nursing leads and team who supported the delivery of this simulation, and the clinical and support staff who maintain and run the HLIU, and the NHS England Contact High Consequence Infectious Diseases Network.

Safe Ventilation Methods against Leaks in Hydrogen Fuel Cell Rooms in Homes

Hydrogen, which has a high energy density and does not emit pollutants, is considered an alternative energy source to replace fossil fuels. Herein, we report an experimental study on hydrogen leaks and ventilation methods for preventing damage caused by leaks from hydrogen fuel cell rooms in homes, among various uses of hydrogen. This experiment was conducted in a temporary space with a volume of 11.484 m3. The supplied pressure, leak-hole size, and leakage amount were adjusted as the experimental conditions. The resulting hydrogen concentrations, which changed according to the operation of the ventilation openings, ventilation fan, and supplied shutoff valve, were measured. The experimental results showed that the reductions in the hydrogen concentration due to the shutoff valve were the most significant. The maximum hydrogen concentration could be reduced by 80% or more if it is 100 times that of the leakage volume or higher. The shutoff valve, ventilation fan, and ventilation openings were required to reduce the concentrations of the fuel cell room hydrogen in a spatially uniform manner. Although the hydrogen concentration in a small hydrogen fuel cell room for home use can rapidly increase, a rapid reduction in the concentration of hydrogen with an appropriate ventilation system has been experimentally proven.

Evone® Flow controlled ventilation: a new device for laryngotracheal surgery.

SUMMARYThe success of laryngotracheal surgery is mainly related to adequate exposure of the airway lumen. To render airway surgery more efficient, many efforts have been made in recent decades to obtain a safe ventilation system which uses an orotracheal tube that is as small as possible. The first attempt was made by introducing the high frequency jet ventilation (HFJV) technology in clinical practice. Nonetheless, HFJV has some risks related to the high pressure needed for ventilation in the catheter. First, during HFJV, the expiration of air from the lungs is a passive backflow on the trachea wall, potentially causing hypercapnia and air trapping. Second, HFJV creates an open ventilation system that leads to aerosolisation of airborne particles with an increased infectious risk for the surgeon. To overcome these issues, an innovative flow-controlled ventilation (FCV) system with a narrow-cuffed catheter (Evone®; Ventinova, Eindhoven, The Netherlands) was introduced in clinical practice. This paper describes our initial experience with the Evone® FCV system, reporting the first 5 cases ventilated with this technology. In this observational study, we evaluate the feasibility and safety of the Evone® system and deliver a critical appraisal of this novel method of ventilation.

High-flow nasal cannula in nonlaser microlaryngoscopic surgery: a prospective study of 19 cases in a chinese population

BackgroundHigh-flow nasal cannula (HFNC) is a new type of oxygen therapy, but its application in surgery remains unclear, we tried to describe the application of HFNC in microlaryngoscopic surgery for the Chinese population.MethodsNineteen adults, American society of anesthesiology class (ASA) 1–2 patients with body mass index < 30 kg.m−2 underwent microlaryngoscopic surgery using HFNC for airway management. Outcomes included apnoea time, intraoperative oxygenation, carbon dioxide value, lactate value, and the relationship between the duration of apnoea time and carbon dioxide levels.ResultsA total of 19 patients underwent vocal cord tumor resection under a microlaryngoscope with HFNC as the sole method of ventilation. The mean age was 39.7 years old, and the mean BMI was 23.9 kg.m−2. The mean apnea time was 21.5 min. The SpO2 of 18 patients remained above 90%, and only 1 patient dropped to 88%. The average basal lactate and highest lactate value was 0.58 mmol. L−1 and 0.68 mmol.L−1. The difference between basal and highest lactate values was statistically significant (P < 0.05). The average highest PaCO2 value was 79.4 mmHg. The PaCO2 increased by 1.68 ± 0.12 mmHg every minute linearly.ConclusionsIn the case series we have observed that HFNC would be safe and effective oxygenation and ventilation technique for selected Chinese patients undergoing non-laser microlaryngoscopic surgery within 30 min. The tubeless technology reduces the complications of tracheal intubation and jet ventilation and clears the surgical field of vision.Trial registrationChinese Clinical Trial Registry (ChiCTR100049144).

Neonatal Applications of Heliox: A Practical Review.

Heliox is a mixture of helium and oxygen that may be utilized as an alternative to air-oxygen during the ventilatory support in the neonate. Special physical properties of Heliox, particularly low density, allow for improved gas flow and diffusion. First reports of Heliox use in the pediatric population were published in 1930s; however, this therapy has never gained widespread popularity despite its described beneficial effects. Historically, this was largely due to technical challenges associated with Heliox ventilation that significantly limited its use and realization of large-scale clinical trials. However, nowadays several commercially available ventilators allow easy and safe ventilation with both conventional and non-invasive modes. In the era of minimally invasive respiratory interventions in the newborn Heliox could be seen as a therapy that may potentially decrease the risk of non-invasive ventilation failure. This review presents pathophysiologic rationale for the use of Heliox in the newborn, and summarizes available data regarding applications of Heliox in the setting of neonatal intensive care unit based on clinical studies and findings from animal models. Mechanisms of action and practical aspects of Heliox delivery are thoroughly discussed. Finally, future research directions for neonatal use of Heliox are proposed.

Model-based patient matching for in-parallel pressure-controlled ventilation

BackgroundSurges of COVID-19 infections have led to insufficient supply of mechanical ventilators (MV), resulting in rationing of MV care. In-parallel, co-mechanical ventilation (Co-MV) of multiple patients is a potential solution. However, due to lack of testing, there is currently no means to match ventilation requirements or patients, with no guidelines to date. In this research, we have developed a model-based method for patient matching for pressure control mode MV.MethodsThe model-based method uses a single-compartment lung model (SCM) to simulate the resultant tidal volume of patient pairs at a set ventilation setting. If both patients meet specified safe ventilation criteria under similar ventilation settings, the actual mechanical ventilator settings for Co-MV are determined via simulation using a double-compartment lung model (DCM). This method allows clinicians to analyse Co-MV in silico, before clinical implementation.ResultsThe proposed method demonstrates successful patient matching and MV setting in a model-based simulation as well as good discrimination to avoid mismatched patient pairs. The pairing process is based on model-based, patient-specific respiratory mechanics identified from measured data to provide useful information for guiding care. Specifically, the matching is performed via estimation of MV delivered tidal volume (mL/kg) based on patient-specific respiratory mechanics. This information can provide insights for the clinicians to evaluate the subsequent effects of Co-MV. In addition, it was also found that Co-MV patients with highly restrictive respiratory mechanics and obese patients must be performed with extra care.ConclusionThis approach allows clinicians to analyse patient matching in a virtual environment without patient risk. The approach is tested in simulation, but the results justify the necessary clinical validation in human trials.

Pressure-Regulated Ventilator Splitting for Disaster Relief: Design, Testing, and Clinical Experience.

The coronavirus disease 2019 (COVID-19) pandemic has revealed that even the best-resourced hospitals may lack sufficient ventilators to support patients under surge conditions. During a pandemic or mass trauma, an affordable, low-maintenance, off-the-shelf device that would allow health care teams to rapidly expand their ventilator capacity could prove lifesaving, but only if it can be safely integrated into a complex and rapidly changing clinical environment. Here, we define an approach to safe ventilator sharing that prioritizes predictable and independent care of patients sharing a ventilator. Subsequently, we detail the design and testing of a ventilator-splitting circuit that follows this approach and describe our clinical experience with this circuit during the COVID-19 pandemic. This circuit was able to provide individualized and titratable ventilatory support with individualized positive end-expiratory pressure (PEEP) to 2 critically ill patients at the same time, while insulating each patient from changes in the other's condition. We share insights from our experience using this technology in the intensive care unit and outline recommendations for future clinical applications.

Challenges with pediatric anesthesia and intraoperative ventilation of the child in the resource-constrained setting.

The systemic challenges in providing safe anesthesia, including safe ventilation, to children in resource-constrained settings are many. For anesthesia providers caring for children, the lack of appropriate equipment, inadequate anesthesia workforce and deficiencies in postoperative care are especially difficult. The clinical decisions made by anesthesia providers around when and how to ventilate a child for surgery are influenced by all of these factors and can result in patient management which may vary significantly from that in a high-resource setting. This educational review considers the intraoperative ventilation of a small child in a resource-constrained setting and discusses specific challenges and context-sensitive solutions.

Randomized crossover trial to compare driving pressures in a closed-loop and a conventional mechanical ventilation mode in pediatric patients.

In mechanically ventilated patients, driving pressure (ΔP) represents the dynamic stress applied to the respiratory system and is related to ICU mortality. An evolution of the Adaptive Support Ventilation algorithm (ASV® 1.1) minimizes inspiratory pressure in addition to minimizing the work of breathing. We hypothesized that ASV 1.1 would result in lower ΔP than the ΔP measured in APV-CMV (controlled mandatory ventilation with adaptive pressure ventilation) mode with physician-tailored settings. The aim of this randomized crossover trial was therefore to compare ΔP in ASV 1.1 with ΔP in physician-tailored APV-CMV mode. Pediatric patients admitted to the PICU with heterogeneous-lung disease were enrolled if they were ventilated invasively with no detectable respiratory effort, hemodynamic instability, or significant airway leak around the endotracheal tube. We compared two 60-minperiods of ventilation in APV-CMV and ASV 1.1, which were determined by randomization and separated by 30-minwashout periods. Settings were adjusted to reach the same minute ventilation in both modes. ΔP was calculated as the difference between plateau pressure and total PEEP measured using end-inspiratory and end-expiratory occlusions, respectively. There were 26 patients enrolled with a median age of 16 (9-25 [IQR]) months. The median ΔP for these patients was 10.4 (8.5-12.1 [IQR]) and 12.4 (10.5-15.3 [IQR]) cmH2O in the ASV 1.1 and APV-CMV periods, respectively (p < .001). The median tidal volume (VT) selected by the ASV 1.1 algorithm was 6.4 (5.1-7.3 [IQR]) ml/kg and RR was 41 (33 50 [IQR]) b/min, whereas the median of the same values for the APV-CMV period was 7.9 (6.8-8.3 [IQR]) ml/kg and 31 (26-41[IQR]) b/min, respectively. In both ASV 1.1 and APV-CMV modes, the highest ΔP was used to ventilate those patients with restrictive lung conditions at baseline. In this randomized crossover trial, ΔP in ASV 1.1 was lower compared to ΔP in physician-tailored APV-CMV mode in pediatric patients with different lung conditions. The use of ASV 1.1 may therefore result in continued, safe ventilation in a heterogeneous pediatric patient group.

Automated mechanical ventilation using Adaptive Support Ventilation versus conventional ventilation including ventilator length of stay, mortality, and professional social aspects of adoption of new technology.

Background Automation of mechanical ventilation allows for reduction of variation in patient management and has the potential to provide increased patient safety by strict adherence to computer driven ventilator protocols. Methods: A retrospective, observational study compared a group of 196 of general ICU patients managed exclusively on automated mechanical ventilation, adaptive support ventilation (ASV), to another group of 684 managed by usual, non-automated mechanical ventilation (No ASV). The data was collected in a unique access database designed to collect data for assessment of mechanical ventilation outcomes in a small medical center ICU. Results: The length of ventilator stay was non-significant between both groups, (81.7 ± 35.2 hours) in the ASV group; vs. (94.1 ± 35.1 hours) in the No ASV. Percent mortality was significantly less in the ASV group, 8.6% compared to 27.3% in the No ASV. Conclusion: Automated ventilation appears to be a safe ventilator strategy; however, cause effect relationships cannot be determined without further, more sophisticated studies. Keywords: Closed loop ventilation, ASV, Ventilator length of stay, Percent minute ventilation

Laryngeal mask airway protector generates higher oropharyngeal leak pressures compared to the laryngeal mask airway supreme: A randomized clinical trial in the ambulatory surgery unit.

Background and Aims:The Laryngeal Mask Airway (LMA) Protector™ is one of the latest introduced supraglottic airway devices. It provides access and functional separation of the respiratory and digestive tracts. Compared to the LMA Supreme™, it has two digestive ports, one to provide suction in the pharyngeal region and one for gastric tube insertion. High oropharyngeal leak pressure is a marker for safe ventilation when using LMA devices. We hypothesized that oropharyngeal leak pressure of the LMA Protector™ is 5 cm H2O higher than the oropharyngeal leak pressure of the LMA Supreme™ at various cuff volumes. Secondary outcome measures were ease of insertion of both masks, fiberoptic confirmation of correct positioning, failures of insertion, presence of blood staining, sore throat, presence of air leak and insertion time.Material and Methods:American Society of Anesthesiologists (ASA) I-III patients aged >18 years, scheduled for elective minor ambulatory surgery under general anesthesia with a LMA were included. Patients were randomized in the LMA Protector™ or LMA Supreme™ group based on a computer-generated random sequence table. After general anesthesia induction, oropharyngeal leak pressures were measured.Results:Oropharyngeal leak pressures were significantly higher (P < 0.0001) for LMA Protector™ compared to LMA Supreme™ at different cuff volumes and a cuff pressure of 65 cm H2O. Insertion time was significantly higher for the LMA Protector™ (29 sec) [interquartile range (IQR) 23, 35] compared to the LMA Supreme™ (19 sec) (IQR 16, 22) (P < 0.0001). There were no statistically significant differences in ease of insertion (number of attempts for succesful positioning), failures of insertion, presence of blood staining, sore throat or presence of air leak.Conclusion:Oropharyngeal leak pressures were consistently higher (>5 cm H2O) for LMA Protector™ compared to LMA Supreme™. LMA Protector™, therefore, allows effective ventilation at higher airway pressures than LMA Supreme™.Trial Registration:http://clinicaltrials.gov.NCT03462550.

Newborn resuscitation devices: The known unknowns and the unknown unknowns

Infant resuscitation devices used at birth must be capable of delivering adequate and consistent ventilation in a controlled and predictable manner to a wide patient weight range, and combinations of transitional lung states. Manual inflation resuscitation devices delivering positive pressure lung inflation at birth can be classified broadly into two types: 1) flow generating, ie silicone self-inflating bags (SIB) also known as bag valve mask (BVM) and 2) flow dependent, ie anaesthetic flow inflating bag (FIB) and t-piece resuscitator (TPR) systems (eg: Neopuff, GE Panda and Draeger Resuscitaires). Globalization, lower production costs, and an expanding market need for devices, has led to a proliferation of brands (both reusable and single use) within a class type. T-piece resuscitators have become the dominant device particularly in high income countries. There remains a paucity of information on the performance characteristics of these devices and their ability to provide the required respiratory parameters for effective and safe ventilation across the full-expected weight range and lung states to which they will be applied. This review aims to inform current clinical practise on the biomechanical efficiency, reliability and efficacy of the most common devices used to apply PPV to newborns and infants ≤10 kgs.

Unsteady RANS simulations of laboratory ventilation with chemical spills and gas leakages - Toward balanced safety and energy effectiveness

Laboratories generally set high airflow rates, commonly measured by the number of air change per hour (ACH), to maintain safe ventilation environments in case of unintended chemical spills and gas leakages as well as to remove fugitive emissions. However, unnecessary high ACH results in wastage of energy and at times, even inefficient removal of pollutants. Due to the uncertain impact of ACH, the latest ventilation codes and standards provide laboratories the flexibility to establish performance-based minimum airflow rates instead of adopting standard criteria. As such, with high-performance computing resources, this study applies the Unsteady Reynolds-averaged Navier-Stokes (URANS) simulations to explore the optimal ventilation strategies in a chemistry laboratory with high fume hood density, which is typical in National University of Singapore (NUS) but has not been studied. First, a chemical spill experiment was conducted to validate the simulation methods. Subsequently, transient variations of air contaminant concentration were simulated under chemical spills or gas leakages at 2 to 16 ACH with different fume hood operation during the unoccupied period of the laboratory. The simulation results show that when fume hoods are switched off, increasing ACH makes diminishing decreases of peak concentrations and clearance time of pollutants. In comparison, when fume hoods operate at a minimum airflow rate, mutual interference between room and fume hood exhausts are observed. In this case, increasing ACH becomes less effective for improving the laboratory ventilation. Based on the results, recommendations are given to optimize laboratory ventilation strategies during unoccupied period balancing occupational safety and energy conservation.

Public Knowledge

At the time of this writing, like many of you I’m sure, I am largely consumed with planning for a safe return to our physical buildings this fall. Information changes daily if not hourly. Budgets swing wildly as infusions of cash from federal sources do and don’t trickle down to the library’s bottom line. Vaccine mandates come with asterisks and exceptions. In between going round and round about safe ventilation when I don’t know more than I can google about HVAC and thinking through how much sanitizer, plexiglass, and vaccines we’ll need on hand to check out books in the coming academic year, I am reading Hester Blum’s masterful history of polar print culture, The News at the Ends of the Earth . As the climate warms in response to human industrialization, dead letters floated by balloon, buried in cairns, and stuffed into frozen tundra by European and American men seeking a northwest passage and a science of the southern hemisphere emerge from the ice. Drawing from these bits and pieces of arctic and Antarctic communication and the newspapers, playbills, and other print culture explorers made for each other, Blum describes how knowledge is constructed and shared under extreme conditions. As editor of the book reviews section of College &amp; Research Libraries here in the Anthropocene, I have been working through such questions myself.