Continuous Positive Airway Pressure (CPAP) face-mask ventilation is an easy and cheap option to manage a massive influx of patients presenting acute respiratory failure during the SARS-CoV-2 outbreak: A retrospective cohort study

Abstract

Introduction: Because of the COVID-19 pandemic, intensive care units (ICU) can be overwhelmed by the number of hypoxemic patients.

Material and methods: This single centre retrospective observational cohort study took place in a French hospital where the number of patients exceeded the ICU capacity despite an increase from 18 to 32 beds. Because of this, 59 (37%) of the 159 patients requiring ICU care were referred to other hospitals. From 27th March to 23rd April, consecutive patients who had respiratory failure or were unable to maintain an SpO2 > 90%, despite receiving 10-15 l/min of oxygen with a non-rebreather mask, were treated by continuous positive airway pressure (CPAP) unless the ICU physician judged that immediate intubation was indicated. We describe the characteristics, clinical course, and outcomes of these patients. The main outcome under study was CPAP discontinuation.

Results: CPAP was initiated in 49 patients and performed out of ICU in 41 (84%). Median age was 65 years (IQR = 54-71) and 36 (73%) were men. Median respiratory rate before CPAP was 36 (30-40) and median SpO2 was 92% (90-95) under 10 to 15 L/min oxygen flow. Median duration of CPAP was 3 days (IQR = 1-5). Reasons for discontinuation of CPAP were: intubation in 25 (51%), improvement in 16 (33%), poor tolerance in 6 (12%) and death in 2 (4%) patients. A decision not to intubate had been taken for 8 patients, including the 2 who died while on CPAP. Two patients underwent less than one hour CPAP for poor tolerance. In the end, 15 (38%) out of 39 evaluable patients recovered with only CPAP whereas 24 (62%) were intubated.

Conclusions: CPAP is feasible in a non-ICU environment in the context of massive influx of patients. In our cohort up to 1/3 of the patients presenting with acute respiratory failure recovered without intubation.

Fig 1. ICU patient load in Delafontaine Hospital during SARS-CoV-2 outbreak.

* Total number of patients who were intubated in ED or wards, were admitted in ICU or for whom CPAP was initiated. ** Number of patients that required transfer in other hospitals by emergency medical retrieval service (SAMU).

Fig 2. CPAP therapy—patient flow diagram.

* CPAP discontinued for poor tolerance (5 patients), death during treatment (2 patients) and improvement (1 patient).

Fig 3. Factors associated with intubation.

Hazard ratio of intubation adjusted for CT-scan severity (more or less of 50% of lung involved by SARS—CoV2 induced lesions), low saturation (SpO2, < 92% or > 92%), delay in days between hospitalization and CPAP initiation (two groups based on the median value of CPAP delay), use of anticoagulant treatment grouped by dosage: simple dose prophylaxis (1), double dose prophylaxis (2) or curative treatment (3) and treatment with corticosteroids. P values are indicated as the result of likelihood-ratio test. The validity of the proportional hazards assumption was tested using cox.zph() function in R (P values > 0.05) and by visualization of Schoenfeld residuals.