BACKGROUND: Data are needed on the effect of oxygen delivered through a high-flow nasal cannula, as compared with standard oxygen therapy, on intubation and mortality in patients with acute hypoxemic respiratory failure.
METHODS: In this multicenter, open-label trial, we randomly assigned patients who had acute hypoxemic respiratory failure to receive high-flow-oxygen or standard-oxygen therapy. All the patients had a ratio of the partial pressure of arterial oxygen to the fraction of inspired oxygen of 200 or less, a respiratory rate of more than 25 breaths per minute, and pulmonary infiltrate on chest imaging. The primary outcome was death by day 28.
RESULTS: A total of 1116 patients underwent randomization. Of these patients, 1110 (556 in the high-flow-oxygen group and 554 in the standard-oxygen group) were included in the analysis. Mortality at day 28 was 14.6% (in 81 of 556 patients) in the high-flow-oxygen group and 14.6% (in 81 of 554 patients) in the standard-oxygen group (difference, -0.05 percentage points; 95% confidence interval [CI], -4.21 to 4.10; P = 0.98). The incidence of intubation by day 28 was 42.4% (in 236 of 556 patients) in the high-flow-oxygen group and 48.4% (in 268 of 554 patients) in the standard-oxygen group (difference, -5.93 percentage points; 95% CI, -11.78 to -0.08). Serious adverse events (cardiac arrest or pneumothorax) occurred during spontaneous breathing in 13 patients (2.3%) in the high-flow-oxygen group and in 6 patients (1.1%) in the standard-oxygen group.
CONCLUSIONS: Among patients with acute hypoxemic respiratory failure, the use of oxygen delivered through a high-flow nasal cannula did not significantly reduce mortality at day 28. (Funded by the French Ministry of Health and Fisher and Paykel Healthcare; SOHO ClinicalTrials.gov number, NCT04468126.).
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In this study, 1,110 patients with acute hypoxic respiratory failure were evenly divided to receive standard isobaric oxygenation or high-flow oxygen. At 28 days, there was no mortality difference. Although this trial seems to show therapeutic equivalence, there were nearly 14,500 patients in the original dataset in the ICU, of whom just over 10,000 had acute hypoxemic respiratory failure (not prospectively defined). The many exclusion criteria whittled the group nearly 90%, limiting the usefulness for bedside guidance.
The SOHO trial failed to decrease mortality compared to standard oxygenation therapy in patients with acute respiratory failure and pulmonary infiltrates. This doesn't mean that HFNC doesn't have value over standard oxygen therapy. Although mortality wasn't changed, there was some evidence for a lower rate of intubation with the high-flow nasal cannula. However, like most studies, there may be other factors that account for the mortality rate, especially since the mortality rate was lower than expected. Regardless, high-flow nasal cannula did not change 30-day mortality in these patients.
Well done RCT but the results are relatively consistent with previous evidence summaries.
This RCT finds that for patients admitted to ICU with acute hypoxemic respiratory failure, administration of high-flow oxygen did not reduce mortality compared with standard oxygen, despite reducing the risk for intubation and substantially improving patient-perceived dyspnea. These findings are unexpected as high-flow oxygen has been widely adopted in clinical practice in recent years based on the expectation that it would improve serious outcomes. However, this trial enrolled patients already admitted to ICU and may not capture the potential for high-flow oxygen to avoid ICU admission and associated adverse outcomes. The different causes of death in each group suggest that the mortality benefits of avoiding intubation in the high-flow group may have been offset by delays in receiving more invasive and aggressive management of respiratory and circulatory failure, thereby increasing mortality.
