Extradural analgesia in the first stage of labour.

We have studied 42 healthy parturients with singleton vertex pregnancies, who were in the first stage of labour and requesting extradural analgesia. They were allocated randomly in a double-blind fashion to receive either 0.125% bupivacaine plain or 0.125% bupivacaine with clonidine 120 micrograms. Efficacy of analgesia was evaluated using linear visual analogue scoring (VAS), sensory block was assessed using bilateral pinprick in the mid-clavicular line and sedation scored on a five-point scale. Maternal and fetal cardiovascular variables were measured every 2 min for 20 min, at 30 min and subsequently at 15-min intervals. The reduction in VAS was greater at all times in the bupivacaine-clonidine group (P < 0.01). The median (range) duration of analgesia was greater in the bupivacaine-clonidine group (114.5 (30-243) min) compared with the bupivacaine group (53 (30-100) min) (P < 0.001). Analgesia was associated with a reduction in arterial pressure in both groups, but there were no between-group differences. Maternal heart rate was less than baseline values at 30-90 min in the bupivacaine-clonidine group only. Sedation was greater in the bupivacaine-clonidine group, especially from 15 to 45 min (P < 0.01). There were no differences in fetal heart rate, mode of delivery or Apgar scores between the two groups.