Extracorporeal Respiratory Support During the First and Second Waves of the COVID-19 Pandemic in Spain and Portugal: An Observational, Multicenter, Cohort Study Including 334 Patients

Background: The benefits of the use of extracorporeal membrane oxygenation (ECMO) in patients with severe acute respiratory distress syndrome (ARDS) due to COVID-19 remain controversial. Methods: In this multicenter cohort study, we analyzed all the adult patients with ARDS due to COVID-19 who received extracorporeal respiratory support at 25 ECMO centers (23 in Spain and two in Portugal) during the first and second waves of the pandemic. Follow-up ended on December 1. Our primary aim was to describe this cohort taking into account its evolution during the pandemic. We also investigated hazard ratios for hospital mortality. Findings: A total of 334 patients were included. Patients supported during the second wave [176 (52.7%)] were older (54.6±9.7 vs 50.9±10.6,p=0.001), had more comorbidities, were more frequently coinfected at the start of ECMO [62 (35.2%) vs 37 (23.3%),p=0.028] and were less likely to be treated at a high-volume center [42 (23.9%) vs 54 (34.2%),p=0.008] than those supported during the first wave [158 (47.3%)]. At December 1, 134 (40.1%) patients had died and 49 (14.6%) were still on ECMO. Among patients supported during the first wave, 93 (58.8%) were discharged and all were alive at six months. Older age [HR 3.49 (1.94-6.28),p<0.001, for patients older than 65 years], low-volume center [HR 2.07 (1.19-3.59),p=0.009; for centers attending fewer than 15 cases] and coinfection at the start of ECMO [HR 1.49 (1.02-2.18),p=0.039] were associated with higher risk of hospital mortality, while a higher PEEP at day 3 of ECMO [HR 0.92 (0.86-0.98),p=0.019] was associated with a lower risk of death. Time on mechanical ventilation prior to ECMO was not associated with mortality [HR 1.01 (0.98-1.03),p=0.310]. Interpretation: ECMO support provided at high volume centers should be considered in selected COVID-19 patients. Age and coinfection, but not mechanical ventilation days, should be taken into account at indication assessment. Funding Statement: No funding. Declaration of Interests: None. Ethics Approval Statement: The study protocol was approved by the local ethics committees at all the participating centers.