Inhalational Versus Intravenous Anesthetic Conditioning for Subarachnoid Hemorrhage-Induced Delayed Cerebral Ischemia
Background: Inhalational anesthetics were associated with reduced incidence of angiographic vasospasm and delayed cerebral ischemia (DCI) in aneurysmal subarachnoid hemorrhage (SAH) patients. Whether intravenous anesthetics provide similar level of protection is not known. Methods: Anesthetic data were collected retrospectively for SAH patients who received general anesthesia for aneurysm repair between January 1st, 2014 and May 31, 2018 at two 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 neurologic outcome (measured by disposition at hospital discharge), between the two sites, adjusting for potential confounders. Results: We compared 179 SAH patients receiving inhalational anesthetics at one institution to 206 SAH patients receiving intravenous anesthetics at the second institution. The rates of angiographic vasospasm between inhalational vs intravenous anesthetic groups were 32% vs 52% (OR:0.49, CI:0.32-0.75, p=0.001) and DCI were 21% vs 40% (OR:0.47, CI:0.29-0.74, p=0.001), adjusting for imbalances between sites/groups, Hunt-Hess and Fisher grades, type of aneurysm treatment and ASA status. No impact of anesthetics on neurological outcome at time of discharge was noted with rates of good discharge outcome between inhalational vs intravenous anesthetic groups at (78% vs. 72%, p=0.23). Conclusion: Our data suggests that those who received inhalational vs. intravenous anesthetic for ruptured aneurysm repair had significant protection against SAH-induced angiographic vasospasm and DCI. Although we cannot fully disentangle site-specific vs. 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 SAH patients 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.