Psychomotor and Clinical Assessment of Flumazenil as an Antagonist of Midazolam

The benzodiazepine antagonist flumazenil (0.01 mg/kg) has been compared with doxapram (1 mg/kg) and saline for the reversal of anaesthesia with intravenous midazolam, alfentanil, nitrous oxide in oxygen and isoflurane. The completeness of reversal was assessed by means of a four-choice reaction time test, 1 and 3 h following the antagonist. In addition, the level of sedation was graded using a five-point scale. Psychomotor testing showed that 60 min after administration of the antagonist, there were marked increases in reaction times (P < 0.05) both in the control and doxapram groups, but not in those receiving flumazenil. At 180 min, however, reaction times in all groups had returned to baseline values. In contrast, there was a significant difference in the sedation scores between the saline and flumazenil groups throughout the study period (P < 0.05). During the 4 h following midazolam, there was no evidence of re-sedation in any of the groups despite the relatively high midazolam dosage.