Effect of Injection Speed of Local Anesthetic on Hypotension during Spinal Anesthesia for Cesarean Section

Abstract

Objectives: Maternal hypotension is a common problem during cesarean section under spinal anesthesia. We evaluated the influence of injection speed of local anesthetic to subarachnoid space on maternal hypotension and level of sensory block. Methods: Bupivacaine (0.5%) 9 mg with fentanyl 10 μg was injected to subarachnoid space either quickly (during 20 seconds, 0.1 mL/sec, n=20) or slowly (during 100 seconds, 0.02 mL/sec, n=20) in parturients scheduled for elective cesarean section. The onset and level of sensory block was checked and heart rate and blood pressure was checked by 2.5 minutes during 20 minutes. Hypotension (systolic blood pressure ＜100 mmHg or ＜70% of baseline) was treated with ephedrine. Results: Hypotension occurred 70% of parturients with spinal anesthesia. Slow injection didn’t influence on the onset and level of sensory block and didn’t reduce the incidence of hypotension. But onset of hypotension was delayed. Conclusion: Slow injection (during 100 seconds, 0.02 mL/sec) of local anesthetic delayed onset of hypotension and required less amount of ephedrine. Slow injection of local anesthetic was one of the effective methods for the cardiovascular stability during cesarean section under spinal anesthesia. (Ewha Med J 2012;35(2):83-88)