Outcomes of patients with COVID-19-associated ards treated with hfnc vs. conventional oxygen therapy

ABSTRACT

INTRODUCTION: Variation in practice regarding the use of High Flow Nasal Cannula (HFNC) existed among hospitals during the COVID-19 pandemic. We hypothesized that patients who received HFNC prior to requiring mechanical ventilation (MV) would have improved mortality when compared to patients treated with conventional oxygen therapy (COT). METHODS: We conducted a prospective observational study of patients admitted to a tertiary care center between March and May 2020. We included consecutive adult patients with confirmed COVID-19 related ARDS who required MV. We excluded patients treated with NIV. Demographic data were collected and outcomes were censored at day 28. HFNC was initiated at the treating provider's discretion as well as availability of equipment and negative pressure rooms. Patients receiving HFNC therapy received oxygen at 20-60L/min with FiO2 to keep oxygen saturation >92%. COT was delivered with a non-rebreather mask or reservoir nasal cannula at 10-15L/min. Decision to proceed with MV was at clinician discretion. We used Student's t-test, Wilcoxon Rank-Sum, Fisher's Exact, and Chi-Square for statistical analysis. RESULTS: 92 patients were included. 58% were male and the mean age was 68±12 years. Thirty (33%) patients were treated with HFNC prior to MV. Patients in the COT group had more CAD and CHF when compared to patients in the HFNC group (13 vs 1, p=0.03 and 8 vs. 0, p=0.05). HFNC was provided for a median of 21 (IQR 9-36) hours vs. COT for 4 (IQR 1-11) hours prior to MV (p=<.0001) There was no difference in the initial PaO2/FiO2 ratio (152±62 HFNC vs. 153±67 COT, p-0.95). The mean SOFA score was significantly lower in the HFNC group compared to the COT group (6.6 vs. 7.7, p=0.05). The mortality rate was 30% in the HFNC group versus 52% in the COT group (p=0.05), with a trend toward lower mortality with HFNC (OR 0.38, 95% CI 0.12-1.15, p=0.09) after controlling for other predictors of mortality. CONCLUSIONS: Our results indicate a trend toward mortality benefit in COVID-19 patients with ARDS who were treated with HFNC compared with COT prior to intubation.