The effect of halothane, isoflurane, or sufentanil on the hypertensive response to cerebellar retraction during posterior fossa surgery.

The blood pressure (BP) response to cerebellar retraction during microvascular decompression of the fifth cranial nerve was investigated in 26 ASA physical status 2 or 3 patients with trigeminal neuralgia. One surgeon performed all operations. To determine the effect of three anesthetic techniques on the BP response, patients were randomly assigned to receive halothane, isoflurane, or sufentanil in sufficient doses with 60% nitrous oxide to achieve a precerebellar retraction systolic BP that was 10-20% below the average ward systolic BP (as per standard clinical practice). The resultant doses were halothane 1.65 +/- 0.27 (mean +/- SD) MAC, isoflurane 1.56 +/- 0.17 MAC (P greater than 0.05), and sufentanil 2.7 micrograms/kg (MAC values include 0.6 MAC contribution from 60% nitrous oxide). In all patients BP increased during the cerebellar retractor placement period compared with the preretractor placement period (P less than 0.05). The peak increase in systolic BP in response to cerebellar retraction was 17 +/- 6 mmHg for halothane, 38 +/- 20 mmHg for isoflurane, and 26 +/- 19 mmHg for sufentanil. The difference between halothane and isoflurane was significant (P less than 0.05). Mean and diastolic BP showed similar significant differences. The authors conclude that halothane attenuates the hypertensive response to cerebellar retraction more than isoflurane when administered in approximately 1.6 MAC concentrations (MAC value includes contribution from nitrous oxide).