TARGET-CONTROLLED INFUSION OF ALFENTANIL FOR POSTOPERATIVE ANALGESIA - A FEASIBILITY STUDY AND PHARMACODYNAMIC EVALUATION IN THE EARLY POSTOPERATIVE PERIOD

We have examined the feasibility of target-controlled infusion of alfe ntanil (TCIA) and the pharmacodynamics of alfentanil in the early post operative period. Patients were allocated randomly to one of the three groups to receive balanced anaesthesia with bolus injections of fenta nyl (group F), sufentanil (group S) or alfentanil (group A. In the rec overy room all patients received the same analgesic regimen, comprisin g TCIA. To evaluate the efficacy of postoperative analgesia, pain scor es were measured on a visual analogue scale (VAS) and patients indicat ed a need for additional analgesia. EC(50), the concentration at which , with a 50% probability, patients reported adequate analgesia, was es timated using logistic regression. Six patients did not complain of pa in. The time from the last intraoperative bolus injection of opioid un til patients complained of postoperative pain was shorter (P < 0.05) i n group A (mean 68 min) than in group F (101 min) and group S (136 min ). The time to onset of satisfactory analgesia was comparable in the t hree groups (median 18 min in group F, 15 min in group S and 14 min in group A). EC(50) of alfentanil was determined in 28 patients; mean va lues were 26 ng ml(-1) (group F), 39 ng ml(-1) (group S) and 52 ng ml( -1) (group A). We conclude that TCIA, under the conditions studied, re sulted in a fast onset of adequate analgesia, irrespective of the opio id administered during operation. Also, there was no effect of opioids administered during operation on postoperative pharmacodynamics of al fentanil.