Comparison between high-flow nasal oxygen (HFNO) alternated with non-invasive ventilation (NIV) and HFNO and NIV alone in patients with COVID-19: a retrospective cohort study

Abstract Background Non-invasive respiratory support (conventional oxygen therapy COT, non-invasive ventilation NIV, high-flow nasal oxygen HFNO, and NIV alternated with HFNO NIV + HFNO may reduce the need for invasive mechanical ventilation (IMV) in patients with COVID-19. The outcome of patients treated non-invasively depends on clinical severity at admission. We assessed the need for IMV according to NIV, HFNO, and NIV + HFNO in patients with COVID-19 according to disease severity and evaluated in-hospital survival rates and hospital and intensive care unit (ICU) lengths of stay. Methods This cohort study was conducted using data collected between March 2020 and July 2021. Patients ≥ 18 years admitted to the ICU with a diagnosis of COVID-19 were included. Patients hospitalized for 50% lung damage on chest computed tomography (CT): NIV (13.3%), HFNO (15%), NIV + HFNO (71.6%) ( p = 0.038); SpO 2 /FiO 2 : NIV (271 118–365 mmHg), HFNO (317 254–420 mmHg), NIV + HFNO (229 102–317 mmHg) ( p = 0.001); rate of IMV: NIV (26.1%, p = 0.002), HFNO (22.6%, p = 0.023), NIV + HFNO (46.8%); survival rate: HFNO (83.9%), NIV + HFNO (63.6%) ( p = 0.027); ICU length of stay: NIV (8.5 5–14 days), NIV + HFNO (15 10–25 days ( p < 0.001); hospital length of stay: NIV (13 10–21 days), NIV + HFNO (20 15–30 days) ( p < 0.001). After adjusting for comorbidities, chest CT score and SpO 2 /FiO 2 , the risk of IMV in patients on NIV + HFNO remained high (hazard ratio, 1.88; 95% confidence interval, 1.17–3.04). Conclusions In patients with COVID-19, NIV alternating with HFNO was associated with a higher rate of IMV independent of the presence of comorbidities, chest CT score and SpO 2 /FiO 2 . Trial registration ClinicalTrials.gov identifier: NCT05579080.