Oxygenation Targets and Long-Term Cognitive and Pulmonary Functions in Hypoxemic Respiratory Failure

Abstract

Rationale: In intensive care unit (ICU) patients lower oxygenation targets may impair long-term cognitive function, while higher targets may impair long-term pulmonary function.

Objectives: To assess the effects of a partial pressure of arterial oxygen (PaO₂) target of 60 vs 90 mmHg on one-year cognitive and pulmonary functions in ICU survivors of acute hypoxemic respiratory failure.

Methods: 3654 patients were randomized in the Handling Oxygenation Targets in the ICU and the Handling Oxygenation Targets in COVID-19 trials: 1916 (52.4%) survived at one year, and 1244 (64.9% of survivors) were eligible. We assessed two preplanned one-year outcomes: cognitive function, measured using the global score of the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS), and pulmonary function, evaluated as the percentage of predicted diffusion capacity for carbon monoxide (DLCO).

Measurements and main results: 417/1244 (33.5%) eligible survivors were included, representing 11.4% of the original trial population. Global RBANS score was obtained in 187 survivors in the lower-oxygenation group (mean 78 [standard deviation (SD) 19]) and 188 in the higher-oxygenation group (mean 76 [SD 21]) (adjusted mean difference (MD): 2, 95% confidence interval (CI) -2 to 6). DLCO was measured in 192 survivors in the lower-oxygenation group (mean 68% [SD 22 %-points] and 195 in the higher-oxygenation group (mean 73% [SD 25 %-points]) (adjusted MD: -5 %-points, 95% CI -9 to -1 %-points).

Conclusions: A PaO₂ target of 60 vs 90 mmHg in ICU appeared to result in similar cognitive impairment but might reduce pulmonary diffusion capacity in ICU survivors of hypoxemic respiratory failure included in this one-year follow-up.

Keywords: acute hypoxemic respiratory failure; critical care outcomes; oxygen.