Association between Early Hyperoxia and Neurologic Outcome in Patient with High Grade Aneurysmal Subarachnoid Hemorrhage

Background: Oxygenation support is a common practice in patients with aneurysmal subarachnoid hemorrhage (SAH). The aim of this study was to analyze the association between early hyperoxia and the neurological outcome in patients presenting a High Grade SAH, using the modified Rankin Scale (mRS) at 6 months. Methods: We retrospectively analyzed data of SAH in a single center, retrospective, observational study. The inclusion criteria were patients’ ≥ 18 years-old, under mechanical ventilation upon admission to the intensive care unit (ICU) and presenting an aneurysmal SAH with a WFNS score ≥3. Hyperoxia was defined as PaO2 > 120 mmHg and classified into 3 subgroups: mild (121-200 mmHg), moderate (201-300 mmHg) and severe (> 300 mmHg). Patients with a 6 months-mRS >3 were considered as having a poor outcome. Results: One hundred and thirty-nine patients with aneurysmal SAH were included. 82% of patients were exposed to hyperoxia with predominance of mild hyperoxia (42.8%). A higher yet non-statistical, poor neurologic outcome was identified in the hyperoxic compared to normoxic group (72% vs. 87.7% OR 2.8 [1.02-7.71], p 0.12). Following a multivariate analysis, a statistical trend was identified between the hyperoxic group and a 6-month poor neurological outcome (OR 2.84, 95% CI, 0.99-8.19; p=0.052), but no statistical association was found with delayed cerebral ischemia (OR 1.68, 95% CI, 0.5-5.71, p=0.39) nor with 28-day mortality (OR 2.17, 95% CI, 0.82-5.75, p=0.11). Conclusions: Our findings suggest a statistical trend between early hyperoxia and a poor neurological outcome at 6 months, in patients with a high grade aneurysmal SAH admitted to the ICU. Further, large-scale studies are required to fully evaluate the effects of hyperoxia.