Effect of nimodipine on cerebral blood flow and cerebrovascular reactivity after subarachnoid haemorrhage.

The aim of the present study was to investigate the effect of nimodipine on autoregulation of cerebral blood flow (CBF), CO2 reactivity and cerebral oxygen metabolism (CMRO2) in patients with subarachnoid haemorrhage (SAH). Eight patients with severe SAH were studied with repeated CBF and CMRO2 measurements on the first day of the bleeding and after at least 12 h of treatment of nimodipine. An initial resting study, an autoregulation study and a hyperventilation study was performed. CBF was measured using the 133-Xenon intravenous method. CMRO2 was calculated as AVDO2 x CBF. Nimodipine did not significantly change CBF and CMRO2 in the initial resting study. After induced arterial hypotension intact autoregulation was found before as well as after treatment with nimodipine. Beneficial effects of nimodipine were found on CO2 reactivity and CMRO2 during hypotension that may be explained as a positive effect on cerebral ischaemia.