Comparison of a chloroprocaine--bupivacaine mixture with chloroprocaine and bupivacaine used individually for obstetric epidural analgesia.

Continuous lumbar epidural anesthesia was instituted in 49 healthy parturients who were randomly assigned to three treatment groups: 14 patients received chloroprocaine, 3 per cent; 19 received bupivacaine, 0.5 per cent, and 16 received a mixture containing chloroprocaine, 1.5 per cent, and bupivacaine, 0.375 per cent. Observations relating to the characteristics of the anesthetic block and to maternal and fetal well-being were made by a trained nurse observer. Times to onset of analgesia, times to maximum block, and adequacies of analgesia were similar in all groups. Bupivacaine lasted significantly longer than chloroprocaine or the mixture (68 versus 50 and 52 min, respectively, for the first injection), and caused the least motor block. No clinical superiority could be demonstrate for the mixture as compared with bupivacaine or chloroprocaine used individually. There was no sign of material or fetal toxicity with any of the three treatment regimens.