A comparison of propofol and midazolam by infusion to provide sedation in patients who receive spinal anaesthesia.

Twenty patients scheduled for orthopaedic surgery under spinal anaesthesia received by intravenous infusion either 1% propofol or 0.1% midazolam at a rate adjusted to maintain adequate sedation as judged on a five-point scale. No other anaesthetic or analgesic drugs were given. The mean time to reach the required level of sedation was similar in both groups and the quality and ease of control of sedation were good in all patients. Mean infusion rates were 3.73 mg/kg/hour for propofol and 0.27 mg/hg/hour for midazolam. Airway maintenance was excellent and there were no side effects other than restlessness of the arms in one patient in each group. Recovery, judged by ability to open the eyes and recall date of birth, was significantly more rapid after propofol than after midazolam (2 and 10 minutes respectively after the end of infusion) and two patients in the latter group were unduly drowsy in the initial postoperative period. Pre- and postoperative amnesia were greater in the midazolam group but no patient had recall of peri-operative events. Psychometric tests showed significantly better recovery of higher mental function after propofol for up to 2 hours after surgery.