Comparison of continuous epidural bupivacaine infusion plus either continuous epidural infusion or patient-controlled epidural injection of fentanyl for postoperative analgesia.

We compared the postoperative epidural analgesia provided by the continuous epidural infusion of bupivacaine supplemented with patient-controlled injection (PCA) of epidural fentanyl with that provided by a continuous infusion of bupivacaine supplemented with a continuous epidural infusion of fentanyl. Our patient population comprised 16 ASA physical status I or II patients undergoing laparotomy with a midline incision under general anesthesia combined with bupivacaine epidural analgesia. Post-operatively, a continuous epidural infusion of bupivacaine (0.1 mg.kg-1.h-1) was combined with epidural fentanyl given by either (a) PCA (15-micrograms bolus with a lockout interval of 12 min, n = 8) or (b) continuous infusion (1 microgram.kg-1.h-1, n = 8). In the case of inadequate pain relief in the latter group, the fentanyl infusion rate was increased by 10 micrograms/h. Analgesia evaluated by a visual analogue pain score and by a verbal pain score was similarly effective in both groups. The sedation score was also similar in both groups. The total dose of epidural fentanyl administered during the first 24 h was significantly lower in the PCA group than in the continuous infusion group (405 +/- 110 micrograms vs 1600 +/- 245 micrograms, P less than 0.001). The dose of fentanyl given during each 4-h interval ranged between 40 and 160 micrograms in the PCA group and 251 and 292 micrograms in the continuous infusion group. Clinically detectable respiratory depression was not observed in either group. In conclusion, epidural administration of 0.1 mg.kg-1.h-1 bupivacaine combined with fentanyl provides effective postoperative analgesia with a total dose of fentanyl required that is lower when fentanyl is administered by epidural PCA rather than by continuous epidural infusion.