Effect of high-flow nasal cannula oxygen versus standard oxygen on mortality in patients with acute hypoxaemic respiratory failure: protocol for a multicentre, randomised controlled trial (SOHO)

INTRODUCTION: First-line oxygenation strategy in patients with acute hypoxaemic respiratory failure consists in standard oxygen or high-flow nasal oxygen therapy. Clinical practice guidelines suggest the use of high-flow nasal oxygen rather than standard oxygen. However, findings remain contradictory with a low level of certainty. We hypothesise that compared with standard oxygen, high-flow nasal oxygen may reduce mortality in patients with acute hypoxaemic respiratory failure. METHOD AND ANALYSIS: The Standard Oxygen versus High-flow nasal Oxygen-trial is an investigator-initiated, multicentre, open-label, randomised controlled trial comparing high-flow nasal oxygen versus standard oxygen in patients admitted to an intensive care unit (ICU) for acute respiratory failure with moderate-to-severe hypoxaemia. 1110 patients will be randomly assigned to one of the two groups with a ratio of 1:1. The primary outcome is the number of patients who died 28 days after randomisation. Secondary outcomes include comfort, dyspnoea and oxygenation 1 hour after treatment initiation, the number of patients intubated at day 28, mortality in ICU, in hospital and until day 90, and complications during ICU stay. ETHICS AND DISSEMINATION: The study has been approved by the central Ethics Committee 'Sud Méditerranée III' (2020-07-05) and patients will be included after informed consent. The results will be submitted for publication in peer-reviewed journals. TRIAL REGISTRATION NUMBER: NCT04468126.