Hypotension during spinal anesthesia is one of the major concerns in cesarean section. To achieve adequate spinal anesthesia with less hypotension, we evaluated the viability of sequential subarachnoid injection of two different baricities of bupivacaine. We used plain bupivacaine 5mg to obtain dense anesthesia of the surgical site, followed by hyperbaric bupivacaine 5mg to achieve spread to T5 anesthesia to address visceral pain.
In this double-blind prospective study, 72 parturients undergoing cesarean section were randomized to receive either hyperbaric bupivacaine 10mg or 5mg each of plain and hyperbaric bupivacaine sequentially for spinal anesthesia. Loss of pinprick sensation to T6 was regarded as sufficient for cesarean section to proceed. Characteristics of anesthesia, episodes of hypotension, bradycardia and ephedrine use were assessed by blinded observers.
Demographic data, characteristics of anesthesia, quality of intraoperative anesthesia and Apgar scores were similar in the two groups. Compared to hyperbaric bupivacaine, the combination of plain and hyperbaric bupivacaine provided a marked decrease in the incidence of hypotension (13.9% vs. 66.7%, P<0.001) and side effects related hypotension such as nausea and vomiting (13.9% vs.52.8%, P<0.001). The amount of ephedrine administered was significantly lower in the plain and hyperbaric bupivacaine group (2.2+/-1.0mg vs. 20.5+/-8.7 mg (P<0.001).
Sequential subarachnoid injection of plain and hyperbaric bupivacaine for cesarean section can provide reliable spinal anesthesia with a lower incidence of hypotension and vomiting.