Recovery from fixed-dose midazolam-induced anaesthesia and antagonism with flumazenil for outpatient arthroscopy

Abstract

This study evaluated recovery after a fixed dose of midazolam as induction agent and the influence of flumazenil on recovery parameters in patients undergoing day-case surgery (arthroscopy of the knee). In 40 unpremedicated patients, anaesthesia was induced with midazolam 0.2 mg/kg, vecuronium bromide 0.1 mg/kg intravenously and 3 vol.% isoflurane in oxygen prior to intubation. Anaesthesia was maintained with nitrous oxide 66% in oxygen and 0.9 vol.% isoflurane. Ten minutes after the end of anaesthesia 20 patients received 0.2 mg flumazenil intravenously, followed by increments of 0.1 mg at 60 s intervals until eye opening. Recovery was assessed by the time to eye-opening, to answering five set questions correctly, and to recovering ocular balance (Maddox Wing test), and by comparing pre- and postoperative performance in a pencil and paper test (the p-deletion test). With the exception of ocular balance, all parameters showed a quicker improvement without side-effects in the flumazenil group. After 4 h all patients were fit for discharge. One month after the procedure, all patients were satisfied with the anaesthesia. Full recovery took on average 1.5 days (range between 0 h-10 days). Whilst the technique employing a fixed dose of midazolam as induction agent gives satisfactory intraoperative anaesthesia for day-case arthroscopy, further improvement can be made with the use of flumazenil which hastens recovery.