Choice of local anaesthetic drug for extradural caesarean section. Comparison of 0.5% and 0.75% bupivacaine and 1.5% etidocaine.

One hundred women undergoing elective lower uterine segment Caesarean section under extradural anaesthesia received either 0.5% or 0.75% plain bupivacaine or 1.5% etidocaine with adrenaline 1:200 000 by random allocation. The time taken to establish satisfactory blockade for surgery was significantly shorter in the etidocaine group compared with either of the bupivacaine groups (P less than 0.001). There were no significant differences in the durations of either analgesia or motor blockade in the three groups. The efficacy of the sensory blockade, measured by the incidence of discomfort during the surgical procedure and the requirements for supplementary analgesia or general anaesthesia, was greater in the bupivacaine groups compared with the etidocaine group. Measurement of plasma bupivacaine concentrations in 34 of the patients revealed significantly increased umbilical venous concentrations at the time of birth in those who received 0.75% bupivacaine (P less than 0.05). There was no advantage in the use of bupivacaine in concentrations exceeding 0.5%. Etidocaine 1.5% may be of some value in situations where minimal delay in establishing adequate extradural blockade for surgery is desirable, but in view of its comparatively poor analgesic effects, routine use is not recommended.