Low-dose bupivacaine-fentanyl spinal anesthesia for cesarean delivery

Background and Objectives: The hypotension following spinal anesthesia rema ins commonplace in cesarean delivery. Intrathecal opioids are synergistic w ith local anesthetics and intensify sensory block without increasing sympat hetic block. The combination makes it possible to achieve spinal anesthesia with otherwise inadequate doses of local anesthetic. We hypothesized that this phenomenon could be used to provide spinal anesthesia for cesarean del ivery while incurring less frequent hypotension. Methods: Thirty-two women scheduled for cesarean delivery were divided into 2 groups of patients who received a spinal injection of either 10 mg of is obaric (plain) bupivacaine 0.5% or 5 mg of isobaric bupivacaine with 25 mu g fentanyl added. Each measurement of a systolic blood pressure less than 9 5 mm Hg or a decrease in systolic pressure of greater than 25% from baselin e was considered as hypotension and treated with a bolus of 5 to 10 mg of i ntravenous ephedrine. Results: Spinal block provided surgical anesthesia in all patients. Peak se nsory level was higher (T3 v T4.5) and motor block more intense in the plai n bupivacaine group. The plain bupivacaine patients were more likely to req uire treatment for hypotension (94% v 31%) and had more persistent hypotens ion (4.8 v 0.6 hypotensive measurements per patient) than patients in the m inidose bupivacaine-fentanyl group. Mean ephedrine requirements were 23.8 m g and 2.8 mg, respectively, for the 2 groups. Patients in the plain bupivac aine group also complained of nausea more frequently than patients in the m inidose bupivacaine-fentanyl group (69% v 31%). Conclusions: Bupivacaine 5 mg + fentanyl 25 mu g provided spinal anesthesia for cesarean delivery with less hypotension, vasopressor requirements, and nausea than spinal anesthesia with 10 mg bupivacaine.