Intrathecal Versus Intravenous Fentanyl for Supplementation of Subarachnoid Block During Cesarean Delivery Sahar M. Siddik-Sayyid, MD, FRCA, Marie T. Aouad, MD, Maya I. Jalbout, MD, Mirna I. Zalaket, MD, Carina E. Berzina, MD, and Anis S. Baraka, MD, FRCA Department of Anesthesiology, American University of Beirut, Medical Center, Beirut, Lebanon Forty-eight healthy parturients scheduled for elective cesarean delivery were randomly allocated to receive intrathecally either 12 mg of hyperbaric bupivacaine plus 12.5 g of fentanyl (n = 23) or bupivacaine alone (n = 25). In the latter group, IV 12.5 g of fentanyl was administered immediately after spinal anesthesia. We compared the amount of IV fentanyl required for sup- plementation of the spinal anesthesia during surgery, the intraoperative visual analog scale, the time to the first request for postoperative analgesia, and the inci- dence of adverse effects. Additional IV fentanyl supple- mentation amounting to a mean of 32  35 g was re- quired 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 post- operative analgesia was significantly longer in the In- trathecal 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 Intrathe- cal Fentanyl group (P = 0.01). Also, intraoperative nau- sea and vomiting occurred less frequently in the Intra- thecal Fentanyl group compared with the IV Fentanyl group (8 of 23 vs 17 of 25; P = 0.02). (Anesth Analg 2002;95:209 –13) S pinal anesthesia is often used for elective cesar- ean delivery (1). However, intrathecal (IT) bu- pivacaine alone may be insufficient to provide complete analgesia, despite the high sensory block; one article states that 13% of the patients undergoing cesarean delivery had visceral pain after the IT admin- istration of 15 mg of bupivacaine (2). Furthermore, such large doses of IT bupivacaine were associated with severe hypotension and delayed recovery of mo- tor block (3). 1 Therefore, smaller doses of bupivacaine supplemented by IT opioids have been recommended for spinal anesthesia in parturients undergoing cesar- ean delivery (4 – 8). Although IT opioids supplement spinal anesthesia, that fact alone does not prove that the drug site of analgesic action resides in the spinal cord (9). An experimental study showed that a significant amount of an IT administered lipophilic opioid, such as fent- anyl, is lost by diffusion into the epidural space and subsequently into the plasma (10), suggesting that IT-administered fentanyl may induce analgesia by a systemic rather than by a spinal action. Our hypothesis was that, if IT fentanyl induces an- algesia predominantly through absorption into the bloodstream rather than by a spinal action, it will produce at best the same effect as the same dose injected IV. No previous clinical study has compared IT fentanyl with the same dose of IV fentanyl for supplementation of spinal anesthesia for cesarean de- livery. This study compares the effect of IT fentanyl versus the same dose of IV fentanyl on the amount of intraoperative analgesic supplementation in women undergoing elective cesarean delivery. Also, the onset, duration, and quality of bupivacaine-induced spinal block, the incidence of adverse effects, and the time to the first request for postoperative analgesics were compared between the two groups. Methods After obtaining approval from our IRB and consent from the patients, a randomized, double-blinded, pro- spective study was performed in 48 parturients sched- uled for elective cesarean delivery. Patients were all classified as ASA physical status I or II and had no contraindication to spinal anesthesia. Complicated pregnancies, such as multiple pregnancy, pregnancy- induced hypertension, and morbidly obese patients, Accepted for publication March 5, 2002. Address correspondence and reprint requests to Anis Baraka, MD, FRCA, Department of Anesthesiology, American University of Beirut, PO Box 11-0236, Beirut, Lebanon. Address e-mail to abaraka@aub.edu.lb. 1 Swami A, McHale S, Abbot P, Morgan B. Low dose spinal anesthesia for cesarean section using combined spinal-epidural (CSE) technique [abstract]. Anesth Analg 1993;76:S423. ©2002 by the International Anesthesia Research Society 0003-2999/02 Anesth Analg 2002;95:209–13 209