Anaesthesia techniques for midazolam and flumazenil--an overview.

Midazolam, the latest benzodiazepine agonist, may be used in doses of 0.15 to 0.2 mg.kg-1 for induction of anaesthesia. It provides good correlation between plasma concentration and anaesthetic effect with an interindividual variability of only 20-25%. On this basis, dosage recommendations for midazolam in total intravenous anaesthesia techniques are possible, aiming at hypnotic plasma concentrations of at least 250 ng.ml-1. Due to its biological half-life of 150-180 min and interindividual differences in drug susceptibility, prolonged recovery periods have been observed that can safely and reliably be antagonised by flumazenil, if necessary. It is recommended that flumazenil be administered carefully by titration in increments of 0.1 mg.min-1 to avoid emergence reactions by awakening too fast (tachycardia, hypertension). Usually a mean total dose of 0.4-0.5 mg will lead to prompt awakening.