Hypotension in spinal anesthesia for cesarean section: a comparison of 0.5% hyperbaric bupivacaine and 5% hyperbaric lidocaine.

Hypotension is a common side effect associated with spinal anesthesia. However, there is no previous report comparing the incidence of hypotension between two commonly used local anesthetic agents, bupivacaine and lidocaine. The objective of this study was to compare the incidence of spinal hypotension induced by bupivacaine and lidocaine in parturients undergoing cesarean section. A double blind, randomized controlled trial was conducted in 142 parturients scheduled for cesarean section. The patients were randomized into two groups, 71 each. After receiving 10 ml/kg of normal saline intravenously, patients in the first group were given 2.2 ml of 0.5 per cent hyperbaric bupivacaine plus 0.2 mg of morphine as a spinal anesthetic agent while in the other group, 1.2 ml of 5 per cent hyperbaric lidocaine plus 0.1 mg of epinephrine and 0.2 mg of morphine were administered. Hypotension, defined as 30 per cent less systolic blood pressure than baseline value, was recorded and the patients were treated with 6 mg of ephedrine every 2 minutes until normotension was achieved. There was no statistically significant difference of incidence, onset, duration, and severity of hypotension between the two groups (p > 0.05). The amount of ephedrine used in both groups was also not significantly different. Late onset hypotension occurred after delivery (20-22 minutes after spinal anesthesia was performed) in 17 patients (12%). As such, the rate of hypotension in lidocaine group was comparable to bupivacaine group. Delayed onset hypotension occurring after delivery was noted and these events have never been described. However, the mechanism of late onset hypotension remains unidentified. Thus, bupivacaine and lidocaine can be used interchangeably for spinal anesthesia for elective cesarean section without significant difference in the incidence of hypotension.