7-year survey of anesthesia for cesarean section--comparison of tetracaine and bupivacaine as intrathecal anesthetic agents

BACKGROUND: In our institution, spinal anesthesia is the first choice for cesarean section. After the introduction of bupivacaine in 2000 in Japan, the intrathecal anesthetic agent shifted from tetracaine to bupivacaine. We analyzed the anesthesia for cesarean section in recent 7 years and compared the anesthetic quality of tetracaine with that of bupivacaine. METHODS: The anesthetic records were reviewed in the patients who had received cesarean section between January 1998 and December 2004 at our institution. RESULTS:There were 10456 deliveries during the study period with a cesarean section rate of 28.2% (2947 cases). Ninety-one percent of cesarean section was performed under spinal anesthesia. Spinal anesthetic agent shifted from tetracaine to bupivacaine in 2000-2001, both of which was prepared as a hyperbaric solution and supplemented with 0.1 mg of morphine hydrocloride. Of the 2711 patients in whom a cesarean section was started under spinal anesthesia, 20 (0.7%) required conversion to general anesthesia. Three hundred eighteen patients (11.7%) required some analgesic supplementation. The incidence of intra-operative analgesic supplementation was greater in the patients anesthetized with hyperbaric tetracaine and morphine than in those anesthetized with hyperbaric bupivacaine and morphine (22.96% vs 4.20% ; P<0.01). The conversion rate from spinal to general anesthesia for cesarean section was 0.7%. CONCLUSIONS: Comparing these two intrathecal anesthetic agents, the rate of analgesic supplementation in those anesthetized with bupivacaine was lower than in those anesthetized with tetracaine. This suggests that bupivacaine provides the more profound blockade of the visceral pain than tetracaine, and is superior as a local anesthetic.