Is continuous positive airway pressure therapy in COVID-19 associated with an increased rate of pulmonary barotrauma?

An in-silico porcine model of phosgene-induced lung injury predicts clinically relevant benefits from application of continuous positive airway pressure up to 8 h post exposure

We present the first computational model of the pathophysiological consequences of phosgene-induced lung injury in porcine subjects. Data from experiments previously performed in several cohorts of large healthy juvenile female pigs (111 data points from 37 subjects), including individual arterial blood gas readings, respiratory rate and heart rate, were used to develop the computational model. Close matches are observed between model outputs (PaO2 and PaCO2) and the experimental data, for both terminally anaesthetised and conscious subjects. The model was applied to investigate the effectiveness of continuous positive airway pressure (CPAP) as a pre-hospital treatment method when treatment is initiated at different time points post exposure. The model predicts that clinically relevant benefits are obtained when 10 cmH2O CPAP is initiated within approximately 8 h after exposure. Supplying low-flow oxygen (40%) rather than medical air produced larger clinical benefits than applying higher CPAP pressure levels. This new model can be used as a tool for conducting investigations into ventilation strategies and pharmaceutical treatments for chemical lung injury of diverse aetiology, and for helping to refine and reduce the use of animals in future experimental studies.

The use of continuous positive airway pressure during the second and third waves of the COVID-19 pandemic

Background

In a preliminary study during the first COVID-19 pandemic wave, we reported a high rate of success with continuous positive airway pressure (CPAP) in preventing death and invasive mechanical ventilation (IMV). That study, however, was too small to identify risk factors for mortality, barotrauma and impact on subsequent IMV. Thus, we re-evaluated the efficacy of the same CPAP protocol in a larger series of patients during second and third pandemic waves.

Methods

281 COVID-19 patients with moderate-to-severe acute hypoxaemic respiratory failure (158 full-code and 123 do-not-intubate (DNI)), were managed with high-flow CPAP early in their hospitalisation. IMV was considered after 4 days of unsuccessful CPAP.

Results

The overall recovery rate from respiratory failure was 50% in the DNI and 89% in the full-code group. Among the latter, 71% recovered with CPAP-only, 3% died under CPAP and 26% were intubated after a median CPAP time of 7 days (IQR: 5-12 days). Of the patients who were intubated, 68% recovered and were discharged from the hospital within 28 days. Barotrauma occurred during CPAP in <4% of patients. Age (OR 1.128; p <0.001) and tomographic severity score (OR 1.139; p=0.006) were the only independent predictors of mortality.

Conclusions

Early treatment with CPAP is a safe option for patients with acute hypoxaemic respiratory failure due to COVID-19.

Effect of the Early Combination of Continuous Positive Airway Pressure and High-Flow Nasal Cannula on Mortality and Intubation Rates in Patients With COVID-19 and Acute Respiratory Distress Syndrome. The DUOCOVID Study

INTRODUCTION

Non invasive respiratory support (NIRS) is useful for treating acute respiratory distress syndrome (ARDS) secondary to COVID-19, mainly in mild-moderate stages. Although continuous positive airway pressure (CPAP) seems superior to other NIRS, prolonged periods of use and poor adaptation may contribute to its failure. The combination of CPAP sessions and high-flow nasal cannula (HFNC) breaks could improve comfort and keep respiratory mechanics stable without reducing the benefits of positive airway pressure (PAP). Our study aimed to determine if HFNC+CPAP initiates early lower mortality and endotracheal intubation (ETI) rates.

METHODS

Subjects were admitted to the intermediate respiratory care unit (IRCU) of a COVID-19 monographic hospital between January and September 2021. They were divided according to Early HFNC+CPAP (first 24h, EHC group) and Delayed HFNC+CPAP (after 24h, DHC group). Laboratory data, NIRS parameters, and the ETI and 30-day mortality rates were collected. A multivariate analysis was performed to identify the risk factors associated with these variables.

RESULTS

The median age of the 760 included patients was 57 (IQR 47-66), who were mostly male (66.1%). The median Charlson Comorbidity Index was 2 (IQR 1-3) and 46.8% were obese. The median PaO₂/FiO₂ upon IRCU admission was 95 (IQR 76-126). The ETI rate in the EHC group was 34.5%, with 41.8% for the DHC group (p=0.045), while 30-day mortality was 8.2% and 15.5%, respectively (p=0.002).

CONCLUSIONS

Particularly in the first 24h after IRCU admission, the HFNC+CPAP combination was associated with a reduction in the 30-day mortality and ETI rates in patients with ARDS secondary to COVID-19.