Helmet Continuous Positive Airway Pressure (CPAP) Delivered in Non-ICU Settings Can Provide Safe, Effective Care in Patients with Covid-19 Pneumonia. A Retrospective Study of CPAP Use on a Re-Purposed Medical Ward

Abstract

RationaleSARS-Cov-2 (Covid-19) has constituted an unprecedented challenge to healthcare systems worldwide, including the allocation of finite ICU capacity to those most likely to benefit. Continuous positive airway pressure (CPAP) is frequently used in acute hypoxic respiratory failure (aHRF) and has been recommended for use in patients with Covid-19 pneumonia. We describe our experience using helmet CPAP (StarMed, Italy) on a general respiratory ward re-purposed to provide additional CPAP capacity during the height of the UK's first wave of Covid-19 admissions. MethodSingle-centre retrospective cohort study of all patients with Covid-19 pneumonia admitted for CPAP in a non-ICU setting. All patients admitted through the duration of the ward's re-purposing were included. CPAP was used according to a local Covid-19 aHRF pathway that was modelled upon expert guidance. All patients had a treatment escalation plan (TEP) agreed prior to starting CPAP. A mixture of wall oxygen and air was used to achieve target FiO2. All patients were managed using noninvasive monitoring including continuous pulse oximetry. The primary outcome studied was survival to discharge from hospital. ResultsA total of 67 patients were admitted for CPAP between the 29th March and the 6th May 2020-the duration for which the ward was repurposed. Two-thirds of patients (65.7% 45/67) were candidates for intubation and mechanical ventilation (IMV). Of these, 64.4% (29/45) survived to discharge from hospital with CPAP support alone. 31.1% of patients (14/45) required escalation to IMV, of whom 50% (7/14) survived to discharge. The overall survival in the IMV suitable group was 80% (36/45). Of those who were not suitable for IMV (34.3%, 23/67), the survival rate to discharge was 26% (6/23). ∗ Derived from the arterial blood gas prior to commencement of CPAP Amongst those who went on to require IMV, we found no statistically significant differences between those who survived to discharge and those who did not, when comparing P:F ratios, APACHE II scores or mean CPAP hours prior to commencing IMV. Conclusions This is a large single-centre cohort study of the use of helmet CPAP in a non-ICU setting. The overall survival through to discharge of the 80% (36/45) eligible for escalation to IMV compares favourably with the contemporaneous UK's ICNARC report of 82% survival to discharge in patients receiving only basic respiratory support. Our results also demonstrate that helmet CPAP can be safely deployed in non-ICU settings to provide effective additional CPAP capacity as part of the pandemic response.