Spinal anaesthesia with 0.25% hyperbaric bupivacaine for Caesarean section: effects of volume

To investigate the safety and efficacy of 0.25% hyperbaric bupivacaine for spinal anaesthesia in Caesarean section, we studied 60 parturients allocated randomly to one of three groups. According to the patient's height, groups 1, 2 and 3 received 3.2-3.6 ml (8-9 mg), 3.6-4.0 ml (9-10 mg) and 4.0-4.4 ml (10-11 mg) of 0.25% bupivacaine in 5% glucose, respectively. Subarachnoid injection was performed in the right lateral decubitus position, and parturients were then turned immediately supine with left uterine displacement. Mean spread of sensory analgesia was significantly higher in group 3 (T2-3) than in groups 1 and 2 (T4-5 in each group). Duration of sensory analgesia was significantly longer in groups 2 and 3 than in group 1. Complete motor block of the lower extremities occurred in all patients but in only one in group 1. Onset time and duration of motor block were not significantly different between the three groups. The incidence of hypotension was significantly higher in group 3 (75%) than in groups 1 and 2 (40% in each group). The efficacy of intraoperative analgesia was significantly greater in groups 2 and 3 than in group 1. The incidence of patients requiring analgesics during operation was significantly lower in groups 2 (25%) and 3 (10%) than in group 1 (70%). There was no difference in neonatal condition between the three groups. Spinal anaesthesia with 3.6-4.0 ml of 0.25% bupivacaine in 5% glucose was satisfactory for Caesarean section.