Recovery from propofol anaesthesia supplemented with remifentanil

We have examined the effects on recovery end-points of supplementation of a propofol-based anaesthetic with remifentanil. After induction of anaesthesia with propofol and remifentanil 1.0 microg kg(-1), 15 patients each were randomly allocated to target plasma propofol concentrations of 2, 3, 4 or 5 microg ml(-1) for maintenance of anaesthesia. Remifentanil was administered by infusion for supplementation in doses required for maintenance of adequate anaesthesia. All patients received 50% nitrous oxide in oxygen and ventilation was controlled. The total amount of drugs used and times to different recovery end-points were recorded. Cognitive function was also assessed using a Mini-Mental State questionnaire. The median dose of remifentanil for maintenance of adequate anaesthesia (excluding the initial bolus dose) in the four groups was 0.21, 0.15, 0.11 and 0.13 microg kg(-1) min(-1) respectively (P=0.0026). The median times to eye opening and orientation were shortest in the 2 microg ml(-1) group [6.0 and 6.5 min, 8.5 and 10.8 min, 13.4 and 15.8 min, and 14.2 and 19.5 min respectively in the propofol 2, 3, 4, and 5 microg ml(-1) groups respectively (P<0.001)]. The times to discharge from the recovery ward and the Mini-Mental State scores were not significantly different.