For a study, researchers sought to assess the effect of conservative versus liberal oxygen therapy in mechanically ventilated people with non-hypoxic ischemic encephalopathy (HIE) acute brain disorders in the intensive care unit (ICU). Post-hoc analysis of data from 217 patients with acute brain disorders other than HIE who participated in the ICU Randomized Trial Comparing 2 OXYGEN Therapy Strategies (ICU-ROX). Patients allocated to conservative oxygen spent less time with oxygen saturation≥97% (50.5 [interquartile range (IQR), 18.5–119] vs. 82 h [IQR, 38–164], the absolute difference was -31.5 h (95% CI: -59.6 to -3.4). At 180 days, 38 of 110 conservative oxygen patients (34.5%) and 28 of 104 liberal oxygen patients (26.9%) had died (absolute difference, 7.6 percentage points; 95% CI, -4.7 to 19.9 percentage points; P=0.23; interaction P=0.02 for non-HIE acute brain pathologies versus HIE; interaction P=0.53 for non-HIE acute brain pathologies versus non-neurological conditions). Patients with acute brain problems that were not due to HIE admitted to the intensive care unit and treated with conservative oxygen therapy did not have a substantially lower mortality rate than those treated with liberal oxygen therapy in this post-hoc research. It was necessary to conduct a study with appropriate statistical power to determine whether or not the 180-day mortality point estimate that favored liberal oxygen therapy represented a genuine effect.