Objective: Estimate time to recovery of command-following and associations between hypoxemia with time to recovery of command-following
Methods: In this multi-center, retrospective, cohort study during the initial surge of the United States’ pandemic (March-July 2020) we estimate the time from intubation to recovery of command-following, using Kaplan Meier cumulative-incidence curves and Cox proportional hazard models. Patients were included if admitted to one of three hospitals with severe COVID-19, endotracheal intubation for at least seven days, and impairment of consciousness (Glasgow Coma Scale motor score <6).
Results: 571 patients of the 795 patients recovered command-following. The median time to recovery of command-following was 30 days (95%-confidence interval [CI]:27-32). Median time to recovery of commandfollowing increased by 16 days for patients with at least one episode of an arterial partial pressure of oxygen (PaO2) value ≤55mmHg (p<0.001), and 25% recovered ≥10 days after cessation of mechanical ventilation. The time to recovery of consciousness was associated with hypoxemia (PaO2 ≤55mmHg hazard ratio (HR):0.56; 95%-CI:0.46-0.68; PaO2 ≤70 HR:0.88; 95%-CI:0.85-0.91), and each additional day of hypoxemia decreased the likelihood of recovery, accounting for confounders including sedation. These findings were confirmed among patients without any imagining evidence of structural brain injury (n=199), and in a non-overlapping second surge cohort (N=427, October-April 2021).
Interpretation: Survivors of severe COVID-19 commonly recover consciousness weeks after cessation of mechanical ventilation. Long recovery periods are associated with more severe hypoxemia. This relationship is not explained by sedation or brain injury identified on clinical imaging and should inform decisions about lifesustaining therapies.