Effect of sevoflurane on cerebral perfusion pressure in patients with internal hydrocephalus.

BACKGROUND Due to its confirmed neuroprotective properties, sevoflurane is one of a few anaesthetics used for neuroanaesthesia. Its effects on the cerebral and systemic circulations may be of particular importance in patientswith intracranial pathology. This study aimed to evaluate the effect of sevoflurane at concentrations lower than 1 MAC on cerebral perfusion pressure (CPP) in patients with internal hydrocephalus. METHODS The study was conducted on14 patients with internal hydrocephalus, who underwent ventriculo-peritoneal shunt implantation. After inserting the catheter into the lateral cerebral ventricle, sevoflurane, at 1.1 and 2.2 vol%, was initiated at two successive 15-minute intervals. The intracranial pressure (ICP) was continuously measured; special attention was focused on the values prior to and at the end of each observation period. The following parameters were monitored: mean arterial pressure (MAP), CPP, heart rate, end-tidal CO₂ concentration, core body temperature, and the inspiratory and end-expiratory concentrations of sevoflurane. RESULTS The HR and MAP decreased during successive observation intervals compared to baseline values. Likewise, the CPP decreased from 75.6 ± 2.8 mm Hg to 72.2 ± 2.6 mm Hg to 70.2 ± 0.8 mm Hg. The baseline value for ICP was 16.3 ± 0.6 mm Hg and increased to 17.7 ± 0.8 and 18.9 ± 0.5 mm Hg during the next observation periods. CONCLUSIONS Sevoflurane administered ata concentration below 1MAC to patients with internal hydrocephalus increases the ICP and decreases the MAP, which leads to adecrease in CPP. The CPP decrease is more dependent on depressing the systemic circulatory system than an increased ICP.