ABSTRACT
BACKGROUND: Baricity differences between spinal anesthetic solutions are thought to produce differences in distribution of anesthetics within the subarachnoid space. We evaluated the influence of baricity of bupivacaine on the quality of the block and the incidence of side effects obtained following intrathecal injection of bupivacaine 8 mg with fentanyl 20 microgram. METHODS: Thirty healthy term parturients scheduled for a cesarean section under combined spinalepidural procedures were randomly allocated into Group I, hyperbaric bupivacaine (n = 15); or Group II, isobaric bupivacaine (n = 15). The dose of both groups was bupivacaine 8 mg combined with fentanyl 20 microgram. The maximum level of sensory blockade, time to reach T4 level and maximum level, time to get complete motor recovery and perioperative complications were assessed. RESULTS: Time to sensory block T4, motor block Bromage scale 3, complete resolution of motor block and sensory regression time to T10 was significantly delayed in Group II compared to Group I. Maximal block height, and time to maximal block had no significant differences between the two groups. There were no significant clinical advantages of one preparation over the other. CONCLUSIONS: The data from this study suggests that intrathecal injection of either hyperic or isobaric bupivacaine produces satisfactory anesthesia with similar side effects.