Effects of sevoflurane on intracranial pressure, cerebral blood flow and cerebral metabolism: A dose‐response study in patients subjected to craniotomy for cerebral tumours

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Abstract
Background: Studies concerning the cerebrovascular effects of sevoflurane in patients with space‐occupying lesions are few. This study was carried out as a dose‐response study comparing the effects of increasing sevoflurane concentration (1.5% (0.7 MAC) to 2.5% (1.3 MAC)) on cerebral blood flow (CBF), intracranial pressure (ICP), cerebrovascular resistance (CVR), metabolic rate of oxygen (CMRO2) and CO2‐reactivity in patients subjected to craniotomy for supratentorial brain tumours. Methods: Anaesthesia was induced with propofol/fentanyl/atracurium and maintained with 1.5% sevoflurane in air/oxygen at normocapnia. Blood pressure was maintained constant by ephedrine. In group 1 (n=10), the patients received continuously 1.5% sevoflurane. Subdural ICP, CBF and CMRO2 were measured twice at 30‐min intervals. In group 2 (n=10), sevoflurane concentration was increased from 1.5% to 2.5% after CBF1. CBF2 was measured after 20 min during 2.5% sevoflurane. Finally, CO2‐reactivity was studied in both groups. Results: In group 1, no time‐dependent alterations in CBF, CVR, ICP and CMRO2 were found. In group 2, an increase in sevoflurane from 1.5% to 2.5% resulted in an increase in CBF from 29 ± 10 to 34±12 ml 100g−1 min−1 and a decrease in CVR from 2.7±0.9 to 2.3±1.2 mmHg ml−1 min 100g (P2 were unchanged. CO2‐reactivity was maintained at 1.5% and 2.5% sevoflurane. Conclusion: Sevoflurane is a cerebral vasodilator in patients with cerebral tumours. Sevoflurane increases CBF and decreases CVR in a dose‐dependent manner. CO2‐reactivity is preserved during 1.5% and 2.5% sevoflurane.