Noninvasive ventilation use and ICU mortality in COVID-19-related acute respiratory failure: a retrospective cohort study.

BACKGROUND: Acute hypoxemic respiratory failure is a severe complication of Coronavirus Disease 2019 (COVID-19) frequently requiring Intensive Care Unit (ICU) admission. The association between Noninvasive Ventilation (NIV) and outcomes in critically ill patients remains uncertain. OBJECTIVE: To evaluate the association between NIV use and clinical outcomes in patients with COVID-19-related acute respiratory failure. METHODS: This retrospective cohort study included adults with confirmed COVID-19 admitted to the ICU of a tertiary hospital in Porto Alegre, Brazil, between March and August 2021. Patients were categorized according to two periods with different NIV implementation strategies. Survival was evaluated using Kaplan-Meier analysis, and ICU mortality predictors were assessed using multivariable Cox regression. RESULTS: A total of 296 patients were included. NIV use increased between periods (2.4%vs. 77.8%; p < 0.001). The overall intubation rate was 90.5%, with no significant differences between periods (p = 0.139). Patients admitted during the second period had more severe hypoxemia and higher crude ICU mortality (58.5%vs. 43.2%; p = 0.013). In the multivariable Cox model, absence of NIV use was associated with a lower adjusted hazard of ICU mortality compared with NIV use (HR = 0.383; 95% CI 0.158-0.929; p = 0.034). CONCLUSIONS: NIV use increased markedly but was not associated with lower intubation rates. Patients receiving NIV had higher observed adjusted mortality; however, this association should not be interpreted as evidence of harm from NIV and likely reflects confounding by indication and treatment selection, as NIV was preferentially used in patients with more severe respiratory failure. Prospective studies are needed to clarify the role of NIV in critically ill patients with COVID-19.