Continuous positive airway pressure for respiratory support during COVID-19 pandemic: a frugal approach from bench to bedside

BACKGROUND: We describe a frugal approach (focusing on needs, performance, and costs) to manage a massive influx of COVID-19 patients with acute hypoxemic respiratory failure (AHRF) using the Boussignac valve protected by a filter ("Filter Frugal CPAP", FF-CPAP) in and out the ICU METHODS: (1) A bench study measured the impact of two filters with different mechanical properties on CPAP performances, and pressures were also measured in patients (2) Non-ICU healthcare staff working in COVID-19 intermediate care units were trained with a video tutorial posted on a massive open online course (3) A clinical study assessed the feasibility and safety of using FF-CPAP to maintain oxygenation and manage patients out of the ICU during a massive outbreak RESULTS: Bench assessments showed that adding a filter did not affect the effective pressure delivered to the patient The resistive load induced by the filter variably increased the simulated patient's work of breathing (6-34%) needed to sustain the tidal volume, depending on the filter's resistance, respiratory mechanics and basal inspiratory effort In patients, FF-CPAP achieved pressures similar to those obtained on the bench The massive training tool provided precious information on the use of Boussignac FF-CPAP on COVID-19 patients Then 85 COVID-19 patients with ICU admission criteria over a 1-month period were studied upon FF-CPAP initiation for AHRF FF-CPAP significantly decreased respiratory rate and increased SpO2 Thirty-six (43%) patients presented with respiratory indications for intubation prior to FF-CPAP initiation, and 13 (36%) of them improved without intubation Overall, 31 patients (36%) improved with FF-CPAP alone and 17 patients (20%) did not require ICU admission Patients with a respiratory rate > 32 breaths/min upon FF-CPAP initiation had a higher cumulative probability of intubation (p < 0 001 by log-rank test) CONCLUSION: Adding a filter to the Boussignac valve does not affect the delivered pressure but may variably increase the resistive load depending on the filter used Clinical assessment suggests that FF-CPAP is a frugal solution to provide a ventilatory support and improve oxygenation to numerous patients suffering from AHRF in the context of a massive outbreak