High-flow nasal oxygen versus conventional oxygen therapy in patients with COVID-19 pneumonia and mild hypoxaemia: a randomised controlled trial

Abstract

Rationale: In patients with COVID-19 pneumonia and mild hypoxaemia, the clinical benefit of high-flow nasal oxygen (HFNO) remains unclear. We aimed to examine whether HFNO compared with conventional oxygen therapy (COT) could prevent escalation of respiratory support in this patient population.

Methods: In this multicentre, randomised, parallel-group, open-label trial, patients with COVID-19 pneumonia and peripheral oxygen saturation (SpO2) ≤92% who required oxygen therapy were randomised to HFNO or COT. The primary outcome was the rate of escalation of respiratory support (ie, continuous positive airway pressure, non-invasive ventilation or invasive mechanical ventilation) within 28 days. Among secondary outcomes, clinical recovery was defined as the improvement in oxygenation (SpO2 ≥96% with fractional inspired oxygen (FiO2) ≤30% or partial pressure of arterial carbon dioxide/FiO2 ratio >300 mm Hg).

Results: Among 364 randomised patients, 55 (30.3%) of 181 patients assigned to HFNO and 70 (38.6%) of 181 patients assigned to COT underwent escalation of respiratory support, with no significant difference between groups (absolute risk difference -8.2% (95% CI -18% to +1.4%); RR 0.79 (95% CI 0.59 to 1.05); p=0.09). There was no significant difference in clinical recovery (69.1% vs 60.8%; absolute risk difference 8.2% (95% CI -1.5% to +18.0%), RR 1.14 (95% CI 0.98 to 1.32)), intensive care unit admission (7.7% vs 11.0%, absolute risk difference -3.3% (95% CI -9.3% to +2.6%)), and in hospital length of stay (11 (IQR 8-17) vs 11 (IQR 7-20) days, absolute risk difference -1.0% (95% CI -3.1% to +1.1%)).

Conclusions: Among patients with COVID-19 pneumonia and mild hypoxaemia, the use of HFNO did not significantly reduce the likelihood of escalation of respiratory support.

Trial registration number: NCT04655638.

Keywords: COVID-19; Critical Care; Pneumonia.

Conflict of interest statement

Competing interests: ACh, AG and CG declare a patent, in association with the University of Palermo—Italy (No 102019000020532—Italian Ministry of Economic Development), not discussed in the present study. ACa received honoraria for lectures or consultancies from Breas, Philips (outside the submitted work). CC received honoraria for lectures from Philips, Resmed (outside the submitted work). CG received honoraria for lectures or consultancies from Vivisol, Philips, Mindray, Air Liquide (outside the submitted work). JCW received honoraria for lectures from Vitalaire, Nippon Gases, Philips, Breas and Armstrong Medical (outside the submitted work). The remaining authors declared no competing interests.

© Author(s) (or their employer(s)) 2023. No commercial re-use. See rights and permissions. Published by BMJ.

Figures

Figure 1

Trial profile. aNo need for oxygen: SpO2 >92% or PaO2/FiO2 >300 in room air or no need for oxygen therapy according to clinical judgement, at screening. COT, conventional oxygen therapy; CPAP, continuous positive airway pressure; GCS, Glasgow Coma Scale; FiO2, fraction of inspired oxygen; HFNO, high-flow nasal oxygen; LTOT, long-term oxygen therapy; NIV, non-invasive ventilation; PaCO2, partial pressure of arterial carbon dioxide; PaO2, partial pressure of arterial oxygen; SpO2, peripheral oxygen saturation.

Figure 2

Cumulative incidence of escalation of respiratory support, according to the original assigned intervention.

Figure 3

Primary outcome in predefined subgroups of patients, according to the original assigned intervention. Square sides of data markers are proportional to subgroup sizes. Error bars indicate 95% CIs. The Gail and Simon test for interaction was used. COT, conventional oxygen therapy; HFNO, high-flow nasal oxygen; SPO2, peripheral oxygen saturation.