Early Moderate Hyperoxemia Does Not Predict Outcome After Aneurysmal Subarachnoid Hemorrhage.

Background: Targeting hyperoxemia is common practice in neurocritical care settings, but the safety of hyperoxemia has been questioned.

Objective: To investigate the independent effect of hyperoxemia on outcome in patients with aneurysmal subarachnoid hemorrhage (SAH).

Methods: We included 432 patients with aneurysmal SAH on mechanical ventilation for at least 24 hours after intensive care unit (ICU) admission. Arterial blood gas levels were calculated as time-weighted averages (TWAs) of all blood gas measurements during the first 24 hours in the ICU. Patients were categorized into 3 TWA-PaO2 bands (low, <97.5 mm Hg; intermediate, 97.5-150 mm Hg; high, ≥150 mm Hg). Outcome measures were unfavorable outcome at 3 months (Glasgow Outcome Scale score 1-3) and mortality. Multivariate logistic regression analysis was used to assess the independent effect of oxygen on outcome.

Results: Overall, 28% of patients died, and a total of 53% had an unfavorable outcome at 3 months. Patients with an unfavorable outcome had significantly higher TWA-PaO2 levels compared with patients with a favorable outcome (137 mm Hg vs 118 mm Hg, P < .001). Multivariate analysis demonstrated no significant association between TWA-PaO2 bands and unfavorable outcome (with intermediate PaO2 as a reference, odds ratio [OR] for low PaO2 1.05, 95% confidence interval [CI]: 0.52-2.12, P = .89; OR for high PaO2: 1.09, 95% CI: 0.61-1.97, P = .77) or mortality (with intermediate PaO2 as reference, the OR for low PaO2 was 0.67 (95% CI: 0.30-1.46, P = .31), and the OR for high PaO2 was 0.73 (95% CI: 0.38-1.40, P = .34).

Conclusion: Early moderate hyperoxemia may not increase or decrease the risk of a poor outcome in mechanically ventilated aneurysmal SAH patients.