Use of simple tests to determine the residual effects of the analgesic component of balanced anaesthesia.

In order to evaluate simple means of determining the rate of recovery after general anaesthesia, the usefulness of the critical flicker fusion threshold test, the Maddox wing apparatus and the visual analogue scale were compared. The postanaesthetic recovery score was used as a reference. Two patient groups (n = 15 in each) received, in a randomized double-blind study, a similar balanced anaesthesia for Caesarean section, except that the analgesic component was either fentanyl 2.5 micrograms kg-1 i.v. or buprenorphine 7.5 micrograms kg-1 i.v. Maddox wing apparatus and visual analogue scale were sensitive enough to differentiate between the postanaesthetic residual effects of the two opioids, but critical flicker fusion threshold and, especially, postanaesthetic recovery score were insensitive in this respect. There was no difference between the two patient groups in mean arterial pressure and heart rate. Our results show that the residual effects of different kinds of opioids as an analgesic component of balanced anaesthesia can be differentiated using simple means like Maddox wing apparatus and visual analogue scales.