RESUMEN
The effect of isoflurane on intraventricular pressure (IVP) was examined during nitrous oxide with fentanyl anaesthesia in patients undergoing craniotomy during normocapnia or hypocapnia. Hypocapnic patients (n = 30, PaCO2 3.3 (0.1) kPa) were allocated to three groups (A, B, C; n = 10 each) according to the inspired concentration of isoflurane (1%, 1.5%, 2%). Normocapnic patients (n = 10, PaCO2 4.7 (0.1) kPa) received an inspired concentration of 1% isoflurane (group D). In patients in groups C and D, IVP increased significantly in response to isoflurane (P less than 0.01). In groups A and B, IVP did not change significantly (P greater than 0.05). Mean arterial pressure and cerebral perfusion pressure decreased significantly (P less than 0.001) in all groups in response to isoflurane.