Intrathecal versus intravenous fentanyl for supplementation of subarachnoid block during cesarean delivery.

Unlabelled: Forty-eight healthy parturients scheduled for elective cesarean delivery were randomly allocated to receive intrathecally either 12 mg of hyperbaric bupivacaine plus 12.5 microg of fentanyl (n = 23) or bupivacaine alone (n = 25). In the latter group, IV 12.5 microg of fentanyl was administered immediately after spinal anesthesia. We compared the amount of IV fentanyl required for supplementation of the spinal anesthesia during surgery, the intraoperative visual analog scale, the time to the first request for postoperative analgesia, and the incidence of adverse effects. Additional IV fentanyl supplementation amounting to a mean of 32 +/- 35 microg was required in the IV Fentanyl group, whereas no supple- mentation was required in the Intrathecal Fentanyl group (P = 0.009). The time to the first request for postoperative analgesia was significantly longer in the Intrathecal Fentanyl group than in the IV Fentanyl group (159 +/- 39 min versus 119 +/- 44 min; P = 0.003). The incidence of systolic blood pressure <90 mm Hg and the ephedrine requirements were significantly higher in the IV Fentanyl group as compared with the Intrathecal Fentanyl group (P = 0.01). Also, intraoperative nausea and vomiting occurred less frequently in the Intrathecal Fentanyl group compared with the IV Fentanyl group (8 of 23 vs 17 of 25; P = 0.02).

Implications: Supplementation of spinal bupivacaine anesthesia for cesarean delivery with intrathecal fentanyl provides a better quality of anesthesia and is associated with a decreased incidence of side effects as compared with supplementation with the same dose of IV fentanyl.