Lower oxygenation target for acute hypoxemic respiratory failure does not reduce mortality

At 90 days, patients with acute hypoxemic respiratory failure in the ICU who received oxygen therapy with a lower oxygenation target did not have lower mortality compared with a higher target, according to results of the HOT-ICU trial.

“Our findings lend weight to the utility of conservative oxygen therapy in patients with acute hypoxemic respiratory failure, as compared with the results of the LOCO₂ trial,” Olav L. Schjørring, MD, PhD, from the department of anesthesia and intensive care at Aalborg University Hospital at Aalborg University in Denmark, and colleagues wrote in The New England Journal of Medicine. “At the same time, the results of our trial do not preclude the possibility of clinically important harm or benefit with a lower oxygenation strategy in this population or in other types of critically ill patients.”

The HOT-ICU trial included 2,928 adults (mean age, 70 years; 63.2% men) who were admitted to the ICU 12 hours or less before enrollment and were receiving at least 10 L of oxygen per minute in an open system or had a fraction of inspired oxygen of 0.5 L or more in a closed system. Participants were randomly assigned to receive oxygen therapy with a target partial pressure of oxygen of 60 mm Hg (n = 1,441) or 90 mm Hg (n = 1,447) for 90 days.

The primary outcome was mortality at 90 days. During follow-up, 42.9% of patients in the lower-oxygenation group died compared with 42.4% of patients in the higher-oxygenation group (adjusted RR = 1.02; 95% CI, 0.94-1.11; P = .64), according to the results.

“Notably, we observed a 90-day mortality that was twice as high as had been hypothesized on the basis of data previously obtained in five Danish ICUs,” the researchers wrote. “The higher 90-day mortality in our trial may have been partially due to differences in the types of admissions.”

There was no significant between-group difference in percentage of days patients were alive without life support (lower-oxygenation group, 87.8 vs. higher-oxygenation group, 84.4) or the percentage of days alive after discharge from hospital at 90 days (55.6 vs. 50, respectively), the researchers reported.

The most common serious adverse event experienced in both groups was shock, in 33.9% of patients in the low-oxygenation group and 35.8% in the higher-oxygenation group. Other serious adverse events such as myocardial ischemia (1% vs. 0.5%), ischemic stroke (1.3% vs. 1.6%) and intestinal ischemia (2.2% vs. 2%) were not significantly different between the lower- and higher-oxygenation groups, respectively.