Effects of deliberate hypotension induced by labetalol with isoflurane on neuropsychological function

The effect of deliberate hypotension on brain function measured by neuropsychological tests was studied in 41 adult patients. Twenty-four patients were anaesthetized for middle-ear surgery with deliberate hypotension induced by labetalol with isoflurane (hypotensive group). Seventeen patients without hypotension served as a control group. The mean arterial pressure was 77 +/- 2 mmHg (10.3 +/- 0.3 kPa) before hypotension and 50 +/- 0 mmHg (6.7 +/- 0.0 kPa) during hypotension in the hypotensive group, and 86 +/- 2 mmHg (11.5 +/- 0.3 kPa) during anaesthesia in the control group. The following psychological tests were performed: four subtests of the Wechsler Adult Intelligence Scale (similarities, digit span, vocabulary and digit symbol), Trail-Making tests A and B, Zung tests (self-rating anxiety scale and self-rating depression scale) and two-part memory test battery with immediate and delayed recall. The tests were performed preoperatively and 2 days postoperatively. There were no statistically significant differences between the groups in any of the tests in the changes from preoperative value to postoperative value. The results indicate that hypotension induced by labetalol with isoflurane has no significant harmful effects on mental functions compared to normotensive anaesthesia.