Flumazenil reverses sedation after midazolam-induced general anesthesia in ambulatory surgery patients.

Flumazenil, a specific competitive benzodiazepine antagonist, was evaluated for reversal of residual sedation after midazolam-induced ambulatory general anesthesia. Endotracheal anesthesia was begun with midazolam (mean +/- SD dose 12.4 +/- 2.4 mg), followed by nitrous oxide in oxygen, fentanyl, and succinylcholine, for gynecologic surgery lasting 38.6 +/- 12.5 min. After surgery, 29 women were given repeated injections of small amounts of either flumazenil or placebo until awake and calm. The mean flumazenil dose was 0.83 +/- 0.04 mg. Assessment of recovery was based on psychodiagnostic tests (visual analog sedation scale, Trieger dot, digit symbol substitution), pulse oxygen saturation, and end-expired carbon dioxide tension. Patients given flumazenil scored significantly better than did those given placebo on the psychodiagnostic tests for 5-60 min, but the groups were no longer different 120 and 180 min after the conclusion of surgery. All scores did not return to preoperative values by 180 min. Pulse oxygen saturation and end-expired carbon dioxide tension showed improvement from postoperative levels at 15 min after flumazenil injection. A controllable degree of midazolam reversal was achieved with flumazenil, but the duration of reversal was limited. Caution is needed to avoid premature discharge of ambulatory patients after midazolam-induced general anesthesia during the time that flumazenil is effective.