Pressure Ventilation Research Articles

Lack of Benefit of High Flow Nasal Oxygen Therapy as Ceiling of Treatment for Severe COVID-19 Pneumonitis in Elderly Frail Patients: A Single Centre Observational Study

Background: Severe COVID-19 pneumonitis in elderly frail patients is associated with poor outcomes, and therefore invasive mechanical ventilation is often deemed an inappropriate course of action. Some evidence suggests high-flow nasal oxygen (HFNO) may prevent the need for invasive ventilation in other groups of patients, but whether it is an appropriate ceiling of care for older frail patients is unknown. Methods: We retrospectively identified patients with severe COVID-19 pneumonitis requiring FiO2>60% who were deemed inappropriate for invasive ventilation or non-invasive continuous positive airway pressure ventilation (CPAP). Our local protocol based on national guidance suggested these patients should be considered for HFNO. We observed whether the patients received HFNO or standard oxygen therapy (SOT) and compared mortality and survival time in these groups. Results: We identified 81 patients meeting the inclusion criteria. From this group, 24 received HFNO and 57 received SOT. The HFNO group was similar in age, BMI and co-morbidities to the SOT group but less frail, as determined by the Clinical Frailty Scale (CFS). All 24 patients that received HFNO died in comparison to 46 patients (80.7%) in the SOT group. Mortality in the HFNO group was significantly higher than in the SOT group. Conclusion: Elderly frail patients with severe COVID-19 pneumonitis deemed inappropriate for invasive ventilation and did not benefit from HFNO. Further, HFNO may have been associated with harm in this group.

The impact of inspiratory pressure level on prevention of ventilator-associated pneumonia: A double-blind, randomized clinical trial

BackgroundAtelectasis and pneumonia are highly prevalent in patients under mechanical ventilation. Studies indicate that using ventilation with an open lung concept improves recovery, decreases ventilator-related pneumonia, decreases mortality and leads to faster weaning from the ventilator. Therefore, this study investigated the effect of higher airway pressure on ventilator-associated pneumonia. MethodsThis randomized clinical trial was conducted on 120 patients under mechanical ventilation. The patients were divided into two groups based on ventilator pressure: the control group (pressure level 20) and the intervention group (pressure level 30). Demographic data, disease severity, the incidence of ventilator-associated pneumonia, organ damage, days connected to the ventilator, length of hospitalization in ICU, and mortality were compared between the two groups. ResultsThere was no significant difference in demographic data and disease severity between the two groups. The average Clinical Pulmonary Infection Score in the intervention group was significantly lower than the control group (P = 0.02). The intervention group's average Sequential Organ Failure Assessment score was significantly lower than the control group (p = 0.016). ConclusionsHigh-pressure levels can decrease ventilator-associated pneumonia and organ failure. It is recommended that the study be repeated with a larger, more diverse population.

Breathing patterns and ventilatory efficiency in elderly cardiac patients with and without left ventricular dysfunction before and after exercise-based cardiac rehabilitation: the EU-CaRE study

Abstract Introduction Coronary artery disease (CAD) may progress to left ventricular dysfunction (LVD) and chronic heart failure. A reduced ventilatory efficiency in these patients is associated with worse outcome. However, breathing patterns at rest and during exercise and their change during exercise-based cardiac rehabilitation (exCR) have been poorly described in this population. We aimed to analyse respiratory and gas-exchange parameters in elderly patients with CAD included in a multicentre study on effectiveness of exCR across seven European countries (EU-CaRE). Methods Patients aged 65 years and older with acute (ACS) and chronic coronary syndromes (CCS) who participated in exCR were included. Cardiopulmonary exercise testing (CPET) was performed before (T0) and at termination of exCR (T1), and 12 months after start of exCR (T2). Ventilation (VE), breathing frequency (BF), and end-expiratory carbon dioxide pressure (PetCO2) were measured at rest, at first ventilatory threshold and peak exercise. Ventilatory efficiency, expressed as VE/VCO2 slope and the nadir of VE/VCO2 ratio were measured during the ramp test. Peak oxygen uptake was averaged over 30 s. Breathing parameters over time were compared between patients without and with left ventricular dysfunction (LVD, defined as LV ejection fraction <45%) by mixed linear models corrected for age, sex and body mass index. Results 818 out of 1633 patients of the EU-CaRE study fulfilled inclusion criteria, 151 (18%) had LVD, of these, 86% were in New York Heart Association (NYHA) functional class I. Mean age was 72.5±5.4 years, 21.9% were women, and 79.8% had acute ACS. Compared to patients without LVD, in patients with LVD resting VE was increased 9%, VE/VCO2 slope 14%, and nadir VE/VCO2 ratio 9%, while PetCO2 was reduced at rest and peak exercise by 6%. From before to after exCR, resting ventilation and breathing frequency, as well as VE/VCO2 slope and nadir VE/VCO2 during exercise decreased significantly more in patients with LVD compared to patients without, while improvement in peak oxygen uptake was similar (Figure 1). Conclusions In contrast to their own perception based on NYHA class, patients with LVD had exaggerated breathing at rest and as response to exercise with consistently reduced PetCO2 and ventilatory efficiency. Abnormal breathing patterns may be an early and clinically relevant sign of LVD and linked to increased chemosensitivity and/or abnormal ergoreflex. Exercise-based CR may contribute to improvements of breathing patterns and ventilator efficiency in this population. Funding Acknowledgement Type of funding sources: Public grant(s) – EU funding. Main funding source(s): European Union's Horizon 2020 research and innovation program and Swiss State Secretariat for Education, Research and Innovation for the Swiss consortium partner

Long term feasibility of ultraprotective lung ventilation with low-flow extracorporeal carbon dioxide removal in ARDS patients.

To explore the feasibility of long-term application of ultraprotective ventilation with low flow ECCO2R support in moderate-severe ARDS patients and the reduction of mechanical power (MP) compared to lung protective ventilation. ARDS patients with PaO2/FiO2 < 200, PEEP of 10 cmH2O, tidal volume 6 ml/Kg of predicted body weight (PBW), plateau pressure > 24 cmH2O, MP > 17 J/min were prospectively enrolled. After 2 h tidal volume was reduced to 4-5 ml/kg, respiratory rate (RR) and PEEP were changed to maintain similar minute ventilation and mean airway pressure (MAP) to those obtained at baseline. After 2 h, ECCO2R support was started, RR was decreased and PEEP was increased to maintain similar PaCO2 and MAP, respectively. The only reduction of tidal volume with the increase in RR did not decrease MP. The application of low flow ECCO2R support allowed a reduction of RR from 25 [24-30] to 11 [9-14] bpm and MP from 18 [13-23] to 8 [7-11] J/min. During the following 5 days no changes in mechanics variables and gas exchange occurred. The application of low flow ECCO2R support with ultraprotective ventilation was feasible minimizing the MP without deterioration in oxygenation in ARDS patients.

Long term noninvasive ventilation and continuous positive airway pressure in children with neuromuscular diseases in France

The aim of the study was to describe the characteristics of children with neuromuscular diseases treated with long term noninvasive ventilation or continuous positive airway pressure in France. On June 1st 2019, 387 patients (63% boys, mean age 11.2 ± 5.5 years) were treated with long term noninvasive ventilation/continuous positive airway pressure. Thirty three percent of patients had spinal muscular atrophy, 30% congenital myopathy/dystrophy, 20% Duchenne muscular dystrophy, 7% Steinert myotonic dystrophy, and 9% other neuromuscular diseases. Ninety-four percent of patients were treated with long term noninvasive ventilation and 6% with continuous positive airway pressure. Treatment was initiated electively for 85% of patients, mainly on an abnormal overnight gas exchange recording (38% of patients). Noninvasive ventilation/continuous positive airway pressure was initiated during a respiratory exacerbation in 15% of patients. Mean duration of noninvasive ventilation/continuous positive airway pressure was 3.3 ± 3.1 years. Mean objective long term noninvasive ventilation/continuous positive airway pressure use was 8.0 ± 3.1 h/24. Spinal muscular atrophy, congenital myopathy/dystrophy, and Duchenne muscular dystrophy represented 83% of children with neuromuscular diseases treated with long term noninvasive ventilation in France. Screening for nocturnal hypoventilation was satisfactory as noninvasive ventilation /continuous positive airway pressure was predominantly initiated electively.

Experimental study of unsteady evolution characteristics of ventilated air mass on the cylinder surface

The ventilated air film covered by the surface of the underwater vehicle has an important influence on its hydrodynamic characteristics. In this paper, the development characteristics of the vehicle shoulder ventilated air mass under different environmental pressures and ventilation pressures are studied through experiments. The results show that in the ventilation process, the ventilated air mass reduces the scouring effect of the incoming flow on the exhaust holes and ensures the continuous discharge of the air flow. With increasing ventilation pressure, more gas in the ventilated air mass is entrainment into the ventilated cavity, which can improve the circumferential coverage of the ventilation cavity to the vehicle and increasing the size of the ventilation cavity by about 26.4%. When the ratio of ventilation pressure to environmental pressure is reduced, the occurrence of a re-entrained jet can be restrained, and the entrainment at the end of the ventilated cavity is weakened, which reduces the maximum size of ventilation cavity by about 61.5%.

Evaluation of Common Nasal Cannulas in Neonatal Noninvasive Ventilation (NIV) Using a Novel Neonatal Nasal Model.

PurposeNon-invasive ventilation (NIV) may reduce intubation rates and be especially beneficial in the care of preterm infants, in addition to other care modalities. Currently, ventilators do not display the pressure at the nares but the pressure in the ventilator tubing system. There are several nasal cannulas available for use to deliver NIV. The purpose of this study was to compare the inspiratory pressure on the ventilator to the measured pressure delivered at the nares using three cannula brands (Manufacturer A, Fisher & Paykel; Manufacturer B, Neotech RAM; and Manufacturer C, Hudson RCI).Patients and MethodsThis bench study utilized a 3D printed nasal model, including nares in multiple sizes to accommodate all nasal prongs studied. The nasal adaptors were connected to neonatal test lungs, to simulate patient breathing. Multiple sizes of nasal cannulas from the three manufacturers were tested for inspiratory vs delivered pressure at the patient side of the cannula, using eight combinations of ventilator settings. Each nasal cannula was tested on six Puritan Bennett™ 980 ventilators.ResultsThe measured delivered pressure at the nares was consistently lower than the clinician-set inspiratory pressure. Across all ventilator settings, 7 of the 11 cannulas delivered significantly less pressure at the nares compared to the inspiratory ventilator pressure (p < 0.01). For each cannula, as inspiratory pressure increased, the difference between delivered and inspiratory pressures also increased. The cannula from Manufacturer B consistently demonstrated the greatest differences between set inspiratory and delivered pressures for each ventilator setting.ConclusionThis study demonstrated substantial differences between ventilator inspiratory pressure and measured delivered pressure, which may have clinical significance. Being unaware of the actual airway pressure delivered to the patient may lead to erroneous adjustments to the level of ventilator pressure, which may be especially consequential to those with delicate and developing respiratory systems.

Computed tomography findings of pulmonary interstitial emphysema in COVID-19: Looking through the lens.

Sir, We read Scialpi et al.’s[1] study evaluating the incidence of pulmonary interstitial emphysema (PIE) and other complications detected using computed tomography (CT) in COVID-19 patients. Although the findings are clinically relevant, some key aspects need to be clarified to define a specific impact and better understand. The authors emphasise early detection of the complications using CT that might help us optimise the ventilation option (noninvasive/invasive ventilation) to reduce the severity of complications. Although the basis is essential, there is controversy about the role of applied ventilation options, especially noninvasive ventilation (NIV) as an inducing factor of PIE or as a promoting factor.[2] In this sense, we also do not know how they can be identified and how to establish a better prevention strategy? The authors have summarised the number of PIE patients who received NIV and invasive mechanical ventilation (IMV). The relationship between PIE and NIV will be interesting. We could not establish an adequate interpretation and relationship of NIV with the PIE or other complications as comparative data required are lacking in the authors’ presented data. COVID-19 patients tend to have a higher incidence of barotrauma with IMV.[23] In this context, a comparison of PIE incidence in patients treated with NIV and IMV will help decide the mode of ventilation. Further, the airway pressures and ventilatory pressure setup in PIE and non-PIE patients receiving NIV will also help us optimise settings.[4] Further, we could not find precise mechanisms and possibilities that determine the evolution of different forms of PIE. In the authors’ cohort, variations in PIE were revealed in 25 patients and associated with pneumomediastinum, subcutaneous emphysema, and pneumothorax in 25 (100%), 16 (64%), and 7 (28%), respectively.[1] However, the determining factors that explain this variation allowing the framework of lung-protective strategies, prevention, and early diagnosis in high-risk patients are missing. It will be helpful for the readers if the authors present any such data from the cohort. It will help us plan future studies to evaluate the best tool for prevention and treatment. Author contribution HMRK, AME–observation, literature search, manuscript preparation, and editing. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.

Analysis and Improvement Plan of Chest Compression and Ventilation during Transport

This study aimed to compare the outcomes of manual and automated chest compressions during virtual reality (VR)-based ambulance transport and measure the ventilation and airway pressure provided by different types of portable positive pressure ventilation in the national fire academy. The chest compression depths were 53.78 mm and 49.01 mm for automated and manual chest compressions, respectively, showing that automated chest compression achieved the appropriate compression depth. The compression rates were 101.8 times per min and 122.6 times per min for automated and manual compressions, respectively; however, the manual compression rate was irregular, ranging from 54∼178 times per min. The amounts of ventilation delivered by the portable positive pressure ventilator were 427.01 ml, 302.87 ml and 455.67 ml for models 1, 2 and 3, respectively, showing that models 1 and 3 delivered the appropriate amounts of ventilation. Therefore, automated chest compression is effective regarding compression depth and rate, incomplete release and release rate, hands-off time and compression site during VR-based patient transport. Portable positive pressure ventilators are easy to apply and can be used during patient transport; however, the ventilation varies according to the type used.

Inhibition of peripheral chemoreceptors improves ventilatory efficiency during exercise in heart failure with preserved ejection fraction − a role of tonic activity and acute reflex response

Peripheral chemoreceptors (PChRs) play a significant role in maintaining adequate oxygenation in the bloodstream. PChRs functionality comprises two components: tonic activity (PChT) which regulates ventilation during normoxia and acute reflex response (peripheral chemosensitivity, PChS), which increases ventilation following a specific stimulus. There is a clear link between augmented PChS and exercise intolerance in patients with heart failure with reduced ejection fraction. It has been also shown that inhibition of PChRs leads to the improvement in exercise capacity. However, it has not been established yet: 1) whether similar mechanisms take part in heart failure with preserved ejection fraction (HFpEF) and 2) which component of PChRs functionality (PChT vs. PChS) is responsible for the benefit seen after the acute experimental blockade. To answer those questions we enrolled 12 stable patients with HFpEF. All participants underwent an assessment of PChT (attenuation of minute ventilation in response to low-dose dopamine infusion), PChS (enhancement of minute ventilation in response to hypoxia) and a symptom-limited cardiopulmonary exercise test on cycle ergometer. All tests were placebo-controlled, double-blinded and performed in a randomized order. Under resting conditions and at normoxia dopamine attenuated minute ventilation and systemic vascular resistance (p = 0.03 for both). These changes were not seen with placebo. Dopamine also decreased ventilatory and mean arterial pressure responses to hypoxia (p < 0.05 for both). Inhibition of PChRs led to a decrease in V˙E/V˙CO2 comparing to placebo (36 ± 3.6 vs. 34.3 ± 3.7, p = 0.04), with no effect on peak oxygen consumption. We found a significant relationship between PChT and the relative decrement of V˙E/V˙CO2 on dopamine comparing to placebo (R = 0.76, p = 0.005). There was a trend for correlation between PChS (on placebo) and V˙E/V˙CO2 during placebo infusion (R = 0.56, p = 0.059), but the relative improvement in V˙E/V˙CO2 was not related to the change in PChS (dopamine vs. placebo). We did not find a significant relationship between PChT and PChS. In conclusion, inhibition of PChRs in HFpEF population improves ventilatory efficiency during exercise. Increased PChS is associated with worse (higher) V˙E/V˙CO2, whereas PChT predicts an improvement in V˙E/V˙CO2 after PChRs inhibition. This results may be meaningful for patient selection in further clinical trials involving PChRs modulation.

Endotracheal Intubation Using a Flexible Intubation Endoscope As a Standardized Model for Safe Airway Management in Swine.

Endotracheal intubation is often a basic requirement for translational research in porcine models for various interventions that require a secured airway or high ventilation pressures. Endotracheal intubation is a challenging skill,requiring a minimum number of successful endotracheal intubations to achieve a high success rate under optimal conditions, which is often unachievable for non-anaesthesiology researchers. Due to the specific porcine airway anatomy, a difficult airway can usually be assumed. The impossibility of establishing a secure airway can result in injury, adverse events, or death of the laboratory animal. Using a prospective, randomized, controlled evaluation approach, it has been shown that fiberoptic-assisted endotracheal intubation takes longer but has a higher first-pass success rate than conventional intubation without causing clinically relevant drops in oxygen saturation. This model presents a standardized regimen for endoscopically guided endotracheal intubation, providing a secured airway, especially for researchers who are inexperienced in the technique of endotracheal intubation via direct laryngoscopy. This procedure is expected to minimize animal suffering and unnecessary animal losses.

Automatic oxygen control for reducing extremes of oxygen saturation: a randomised controlled trial

ObjectiveThe objective of this study was to evaluate the efficacy of the automatic oxygen control (A-Fio2) in reducing the percentage of time spent in severe hypoxaemia (Spo2 <80%) in preterm...

Variations of pulse pressure and central venous pressure may predict fluid responsiveness in mechanically ventilated patients during lung recruitment manoeuvre: an ancillary study

BackgroundMaintaining a constant driving pressure during a prolonged sigh breath lung recruitment manoeuvre (LRM) from 20 to 45 cmH20 peak inspiratory pressure in mechanically ventilated patients has been shown to be a functional test to predict fluid responsiveness (FR) when using a linear regression model of hemodynamic parameters, such as central venous pressure (CVP) and pulse pressure (PP). However, two important limitations have been raised, the use of high ventilation pressures and a regression slope calculation that is difficult to apply at bedside. This ancillary study aimed to reanalyse absolute variations of CVP (ΔCVP) and PP (ΔPP) values at lower stages of the LRM, (40, 35, and 30 cm H20 of peak inspiratory pressure) for their ability to predict fluid responsiveness.MethodsRetrospective analysis of a prospective study data set in 18 mechanically ventilated patients, in an intensive care unit. CVP, systemic arterial pressure parameters and stroke volume (SV) were recorded during prolonged LRM followed by a 500 mL crystalloid volume expansion. Patients were considered as fluid responders if SV increased more than 10%. Receiver-operating curves (ROC) analysis with the corresponding grey zone approach were performed.ResultsAreas under the ROC to predict fluid responsiveness for ΔCVP and ΔPP were not different between the successive stepwise increase of inspiratory pressures [0.88 and 0.89 for ΔCVP at 45 and 30 cm H20 (P = 0.89), respectively, and 0.92 and 0.95 for ΔPP at 45 and 30 cm H20, respectively (P = 0.51)]. Using a maximum of 30 cmH2O inspiratory pressure during the LRM, ΔCVP and ΔPP had a threshold value to predict fluid responsiveness of 2 mmHg and 4 mmHg, with sensitivities of 89% and 89% and specificities of 67% and 89%, respectively. Combining ΔPP and ΔCVP decreased the proportion of the patients in the grey zone from 28 to 11% and showed a sensitivity of 88% and a specificity of 83%.ConclusionsA stepwise PEEP elevation recruitment manoeuvre of up to 30 cm H20 may predict fluid responsiveness as well as 45 cm H20. The combination of ΔPP and ΔCVP optimizes the categorization of responder and non-responder patients.

High PEEP Levels during CPR Improve Ventilation without Deleterious Haemodynamic Effects in Pigs.

Background: Invasive ventilation during cardiopulmonary resuscitation (CPR) is very complex due to unique thoracic pressure conditions. Current guidelines do not provide specific recommendations for ventilation during ongoing chest compressions regarding positive end-expiratory pressure (PEEP). This trial examines the cardiopulmonary effects of PEEP application during CPR. Methods: Forty-two German landrace pigs were anaesthetised, instrumented, and randomised into six intervention groups. Three PEEP levels (0, 8, and 16 mbar) were compared in high standard and ultralow tidal volume ventilation. After the induction of ventricular fibrillation, mechanical chest compressions and ventilation were initiated and maintained for thirty minutes. Blood gases, ventilation/perfusion ratio, and electrical impedance tomography loops were taken repeatedly. Ventilation pressures and haemodynamic parameters were measured continuously. Postmortem lung tissue damage was assessed using the diffuse alveolar damage (DAD) score. Statistical analyses were performed using SPSS, and p values <0.05 were considered significant. Results: The driving pressure (Pdrive) showed significantly lower values when using PEEP 16 mbar than when using PEEP 8 mbar (p = 0.045) or PEEP 0 mbar (p < 0.001) when adjusted for the ventilation mode. Substantially increased overall lung damage was detected in the PEEP 0 mbar group (vs. PEEP 8 mbar, p = 0.038; vs. PEEP 16 mbar, p = 0.009). No significant differences in mean arterial pressure could be detected. Conclusion: The use of PEEP during CPR seems beneficial because it optimises ventilation pressures and reduces lung damage without significantly compromising blood pressure. Further studies are needed to examine long-term effects in resuscitated animals.

1009 Severe Thoracic and Abdominal Surgical Emphysema in a Patient with COVID-19 Pneumonia

Abstract Introduction Surgical emphysema is a relatively common occurrence in intensive care unit but its degree of spread in our patient is unusual. We present a case of a young adult with rapid widespread crepitus and worsening respiratory dynamics. Case description 35-year-old male with hypertension, type 2 diabetes and obesity was invasively ventilated for severe COVID-19 pneumonia. He developed reduced chest compliance, required high driving pressures, and had persistent hypoxia despite a high fraction of inspired oxygen. He was ventilated using protocolised ARDSNet lung protective ventilation (LPV) including periods of ventilation in the prone position. After 19 days of ventilation, worsening surgical emphysema was noted following a tracheostomy. Chest radiography demonstrated extensive extra-pulmonary air. Subsequent computed tomography confirmed widespread surgical emphysema from the face to the scrotum, bilateral pneumothoraces and pneumoperitoneum. Bilateral intercostal drains were inserted and LPV was continued. The pneumoperitoneum resolved with conservative management. The patient was mechanically ventilated for 59 days and was discharged home on day 104. Discussion Pneumothorax, pneumomediastinum and surgical emphysema can occur following high-pressure ventilation and surgical tracheostomy. However, pneumoperitoneum with extra-alveolar air collections communicating via potential fascial planes, perivascular sheaths or trans-diaphragmatic extension is rare. The cytokine storm postulated to occur in COVID-19 infection may cause alveolar destruction, leading to Macklin's phenomenon whereby air tracks along peri-bronchial vascular sheaths towards the mediastinum following alveolar rupture. In this patient, prolonged ventilation and high airway pressures probably compounded this effect and led to the complications described.

Prophylactic Postoperative Noninvasive Ventilation in Adults Undergoing Upper Abdominal Surgery: A Systematic Review and Meta-Analysis.

Postoperative pulmonary complications (PPCs) are a leading cause of morbidity and mortality following upper abdominal surgery. Applying either noninvasive ventilation (NIV) or continuous positive airway pressure (CPAP) in the early postoperative period is suggested to prevent PPC. We aimed to assess whether postoperative NIV or CPAP or both prevent PPCs compared with standard care in adults undergoing upper abdominal surgery, including in those identified at higher PPC risk. Additionally, the different interventions used were evaluated to assess whether there is a superior approach. We searched PubMed, Embase' CINAHL, CENTRAL, and Scopus from inception to May 17, 2021. We performed a systematic search of the literature for randomized controlled trials evaluating prophylactic NIV and/or CPAP in the postoperative period. Two authors independently performed study selection and data extraction. Individual study risk of bias was assessed using the PEDro scale, and certainty in outcomes was assessed using the Grading of Recommendations Assessment, Development, and Evaluation framework. We included 17 studies enrolling 6,108 patients. No significant benefit was demonstrated for postoperative NIV/CPAP to reduce PPC (risk ratio [RR], 0.89; 95% CI, 0.78-1.01; very low certainty), including in adults identified at higher PPC risk (RR, 0.91; 95% CI, 0.77-1.07; very low certainty). No intervention approach was identified as superior, and no significant benefit was demonstrated when comparing: 1) CPAP (RR, 0.90; 95% CI, 0.79-1.04; very low certainty), 2) NIV (RR, 0.68; 95% CI, 0.41-1.13; very low certainty), 3) continuous NIV/CPAP (RR, 0.90; 95% CI, 0.77-1.05; very low certainty), or 4) intermittent NIV/CPAP (RR, 0.66; 95% CI, 0.39-1.10; very low certainty) to standard care. These findings suggest routine provision of either prophylactic NIV or CPAP following upper abdominal surgery may not be effective to reduce PPCs' including in those identified at higher risk.

USER PERCEPTION OF NATURAL VENTILATION STRATEGY AT INPATIENT WARD, KUALA KANGSAR HOSPITAL

Hospitals and healthcare facilities are known to be among the most energyintensive buildings. This concern has resulted in a resurgence of sustainability awareness in the built environment. Nowadays, many have adopted environmental strategies such as natural ventilation. It offers a low-cost alternative to remove stale air and replace fresh air efficiently through cross ventilation. Studies have shown that natural ventilation is one of the most energyefficient solutions to improve thermal comfort and hospitals and healthcare facilities will greatly benefit from this initiative. Passive Design has been valued as a key strategy in controlling airborne infection, especially in hospital wards with limited resources. Comparatively, the installation of ceiling-mounted mechanical fans will create a negative ventilation pressure difference. This paper explores the potential of the passive design method based on the experience of inpatient ward users. The study utilised questionnaires based on the end user's experience in a naturally ventilated inpatient ward area. The survey administration method ensures the 51 respondents’ anonymity is preserved especially in a healthcare setting. This investigation shows that natural ventilation provides a higher ventilation rate and is more energy-efficient than mechanical ventilation. Therefore, natural ventilation is a suitable solution in public buildings such as hospitals' inpatient wards. The outcome of this study will be paramount for designers to meet passive design objectives. Consequently, these will be the guidelines and outline information for hospital design in the future.

Evaluation of adequacy of ventilation and gastric insufflation at three levels of inspiratory pressure for facemask ventilation during induction of anaesthesia: A randomised controlled trial

BackgroundIn this study, we aimed to compare three inspiratory pressures during facemask ventilation in paralysed patients regarding the subsequent incidence of gastric insufflation and the adequacy of lung ventilation. MethodsIn this randomised controlled trial, we included adult patients undergoing elective surgery under general anaesthesia. The patients were randomly allocated to receive positive inspiratory pressure (PIP) of 10, 15, or 20 cmH2O during pressure-controlled mask ventilation. Antral cross-sectional area (CSA) was assessed by ultrasound at baseline before mask ventilation and after endotracheal intubation and gastric insufflation was defined as increased CSA after endotracheal intubation > 30% of the baseline measurement. The primary outcome was the incidence of gastric insufflation. Other outcomes included the tidal volume, and the incidence of adequate ventilation (tidal volume of 6–10 mL/kg predicted body weight). ResultsWe analysed data from 36 patients in each group. The number of patients with gastric insufflation was the lowest in the PIP 10 group (0/36 [0%]) in comparison with PIP 15 (2/36 [19%] and PIP 20 36/36 [100%] groups (P-values of 0.019 and < 0.001, respectively). The probability of adequate ventilation at any time point was the highest in PIP 10, followed by PIP 15, and was the lowest in the PIP 20 group. ConclusionAn inspiratory pressure of 10 cmH2O in paralysed patients provided the least risk of gastric insufflation with adequate ventilation during induction of general anaesthesia compared to inspiratory pressure of 15- and 20 cmH2O.

The long-term outcomes of preterm infants receiving non-invasive high-frequency oscillatory ventilation.

ObjectiveTo investigate the clinical outcomes of preterm infants who received non-invasive high-frequency oscillatory ventilation following extubation in a neonatal intensive care unit.MethodsInfants born between 25 and 34 weeks of gestation with a birth weight of <1,500 g, who were admitted into the neonatal intensive care unit of Guangxi Maternal and Child Health Hospital, Nanning, Guangxi, China, requiring mechanical ventilation on admission were randomized to the non-invasive high-frequency ventilation group, nasal intermittent positive pressure ventilation group, or nasal continuous positive airway pressure group following extubation. Their respiratory and neurodevelopmental outcomes were assessed at 12 and 24 months of corrected age.ResultsAmong 149 preterm infants who underwent randomization, 139 completed their treatment in the neonatal intensive care unit (45, 47, 47 in the non-invasive high-frequency ventilation group, nasal intermittent positive pressure ventilation group, or nasal continuous positive airway pressure group, respectively), 113 were assessed at 12-month corrected age, and 110 of 113 were assessed again at 24-month corrected age. There were no differences in the number of times bronchitis, pneumonia, wheezing episodes, and re-hospitalization rates appeared due to respiratory diseases among the three groups (P > 0.05); the pulmonary function tests at 12-month corrected age showed respiratory rate, tidal volume, inspiratory time/expiratory time, time to peak expiratory flow/expiratory time, volume at peak expiratory flow/expiratory volume, expiratory flow at 25, 50, and 75% tidal volume were all similar among infants from the 3 groups (P > 0.05). There were no differences in the rates of neurodevelopmental impairment among the three groups at 24-month corrected age (P > 0.05).ConclusionAs post-extubation respiratory support in preterm infants, non-invasive high-frequency ventilation did not increase the rates of long-term respiratory morbidities and neurodevelopmental impairment compared with nasal intermittent positive pressure ventilation and nasal continuous positive airway pressure.

Community-acquired pneumonia and non-invasive ventilation-a valid ICU avoidance strategy?

The British Thoracic Society guidelines state that neither non-invasive ventilation (NIV) nor continuous positive airway pressure support is routinely indicated in the management of patients with respiratory failure due to community-acquired pneumonia (CAP).1 These guidelines were published some years ago—is there now more robust recent evidence to support the use of NIV in pneumonia? We therefore welcome the meta-analysis by Dr Klefti and colleagues at the University of Edinburgh which addresses this important question. In more recent times, the QJM has been publishing relevant meta-analysis on clinically relevant issues related to acute coronavirus disease 2019 (COVID-19) infection.2–5 As we learn to live with COVID, we welcome reviews relating to pertinent non-COVID clinical questions. In relation to the pertinent clinical question—is NIV indicated in the management of CAP—the authors report a significant benefit, in particular with regards to NIV significantly reducing the rate of endotracheal intubation (risk ratio (RR) 0.46, 95% confidence interval (CI) [0.26–0.79]), and ICU mortality rate (RR 0.3, 95% CI [0.09–0.93]). National clinical guidelines are the foundation stone for best clinical practice. The British Thoracic Society last published full clinical guidelines for the management of CAP 13 years ago—perhaps it is time for an update?