Effect of Intra-Arterial and Intravenous Nimodipine Therapy of Cerebral Vasospasm After Subarachnoid Hemorrhage on Cerebrovascular Reactivity and Oxygenation

Abstract

Background: For the treatment and prevention of delayed cerebral ischemia after subarachnoid hemorrhage, the vasodilating agent nimodipine (NDP) is widely employed. This study investigates the effect of NDP on cerebrovascular autoregulation, assessed by pressure reactivity index (PRx), and brain tissue oxygenation (p_brO₂) when given continuously intravenously as an intra-arterial bolus or during continuous intra-arterial therapy.

Methods: Computerized continuous neuromonitoring data (intracranial pressure, mean arterial pressure, cerebral perfusion pressure [CPP], p_brO₂, PRx) of 105 patients with aneurysmal SAH were retrospectively evaluated. The effect of NDP on all parameters was compared when applied intra-arterially for the treatment of severe macrovasospasm leading to perfusion deficits as either bolus treatment (n = 111 in 37 patients) or continuous infusion (n = 20 patients) to patients without or with only mild macrovasospasm who received either intravenous NDP or no NDP at all.

Results: Compared with patients without treatment, the intravenous application of NDP was associated with a significantly higher PRx. Autoregulation was strongly and long lastingly affected (high PRx) in continuous intra-arterial NDP infusion, accompanied by a sustained improvement of p_brO₂. Intra-arterial bolus NDP application resulted as well in a significant increase of p_brO₂ and PRx; the induced effect, however, was transient and subsided within 6 hours. Intracranial pressure, mean arterial pressure, and CPP were not affected during the monitoring period.

Conclusion: The pharmacologically induced alteration of the cerebrovascular autoregulation by NDP correlates with changes of p_brO₂ and indicates a beneficial effect on cerebral blood flow if CPP is maintained. This effect is limited to a few hours after bolus treatment and milder for intravenous compared with intra-arterial application.

Keywords: Brain tissue oxygen; Cerebral autoregulation; Intra-arterial nimodipine; Nimodipine; Subarachnoid hemorrhage; Vasospasm.