Length of Pre-Ecmo Mechanical Ventilation Is Not Associated with Mortality in Patients with Covid-19

ABSTRACT

INTRODUCTION: Previous studies suggest that delayed initiation of extracorporeal membrane oxygenation (ECMO) is associated with higher patient mortality. Hence, we hypothesized that prolonged invasive mechanical ventilation (IMV) prior to ECMO was associated with higher mortality in patients with COVID-19. METHOD(S) The COVID-19 Critical Care Consortium, a prospective international multicenter registry, was queried for all patients with COVID-19 infection who received IMV and ECMO. Patients who were intubated prior to transfer to a study site were excluded. The primary variable was number of days on IMV prior to ECMO initiation and study endpoint was death or discharge from the study site. Cox proportional hazards model for the time between ECMO initiation and death was built using covariates including age, gender, selected comorbidities, and time intervals from ICU admission to IMV and IMV to ECMO initiation. RESULT(S) Between 1/1/2020 and 6/6/2022, A total of 593 patients from 107 study sites and 25 countries were included in the analysis. In this cohort, the median age was 50 (Interquartile range [IQR] 40-58) years. Obesity and hypertension were prevalent among 220 (38.4%) and 223 (38.8%) of the patients, respectively. Twenty-four (4.2%) patients had chronic pulmonary disease. Prior to ECMO initiation, patients spent a median of 3.68 (IQR 1.36-8.07) days in the ICU and a median of 2.49 (IQR 0.88-5.65) days on IMV. Overall mortality was 47.2% with 3.9% patients' status not finalized or unknown. According to the final survival model, the number of days on IMV prior to ECMO initiation was not associated with mortality. The hazard ratios for 0, 3, 7, and 14 days of pre-ECMO IMV were 0.94 (95% confidence interval [CI] 0.83 to 1.07), 1.02 (95% CI 0.97 to 1.08), 1.09 (95% CI 0.92 to 1.3) and 1.09 (95% CI 0.83 to 1.42), respectively. Other noticeable contributory factors in the model included age and gender. CONCLUSION(S) Among patients with COVID-19 who received ECMO, the length of pre-ECMO IMV was not associated with hospital mortality. Further studies evaluating the ventilator settings before and after ECMO initiation are needed.