BACKGROUND: Inhalational anesthetics were associated with reduced incidence of angiographic vasospasm and delayedcerebral ischemia (DCI) in patients with aneurysmal subarachnoid hemorrhage (SAH). Whether intravenous anesthetics
provide similar level of protection is not known.

METHODS: Anesthetic data were collected retrospectively for patients with SAH who received general anesthesia for aneurysmrepair between January 1, 2014 and May 31, 2018, at 2 academic centers in the United States (one employing primarily
inhalational and the other primarily intravenous anesthesia with propofol). We compared the outcomes of angiographic
vasospasm, DCI, and neurological outcome (measured by disposition at hospital discharge), between the 2 sites, adjusting
for potential confounders.

RESULTS: We compared 179 patients with SAH receiving inhalational anesthetics at one institution to 206 patients withSAH receiving intravenous anesthetics at the second institution. The rates of angiographic vasospasm between inhalational
versus intravenous anesthetic groups were 32% versus 52% (odds ratio, 0.49 [CI, 0.32–0.75]; P=0.001) and DCI were21% versus 40% (odds ratio, 0.47 [CI, 0.29–0.74]; P=0.001), adjusting for imbalances between sites/groups, Hunt-Hessand Fisher grades, type of aneurysm treatment, and American Society of Anesthesiology status. No impact of anesthetics
on neurological outcome at time of discharge was noted with rates of good discharge outcome between inhalational versus
intravenous anesthetic groups at (78% versus 72%, P=0.23).

CONCLUSIONS: Our data suggest that those who received inhalational versus intravenous anesthetic for ruptured aneurysm repairhad significant protection against SAH-induced angiographic vasospasm and DCI. Although we cannot fully disentangle site-
specific versus anesthetic effects in this comparative study, these results, when coupled with preclinical data demonstrating
a similar protective effect of inhalational anesthetics on vasospasm and DCI, suggest that inhalational anesthetics may be
preferable for patients with SAH undergoing aneurysm repair. Additional investigations examining the effect of inhalational
anesthetics on other SAH outcomes such as early brain injury and long-term neurological outcomes are warranted.

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