Continuous infusion epidural analgesia for obstetrics: bupivacaine versus bupivacaine-fentanyl mixture.

Continuous infusion epidural analgesia (CIEA) using a mixture of bupivacaine andfentanyl was evaluated in this randomized. double-blind study involving 75 nulliparous women by comparing the mixture (Group I, Bupivacaine 0.125% and fentanyl 4 μg · ml−1 - 24 patients) with two concentrations of bupivacaine alone (Group 11, bupivacaine 0.25% - 24 patients; and Group III, bupivacaine 0.125% - 27 patients). Epidural anaesthesia was established in Group I with 6 ml 0.125% bupivacaine with fentanyl 50 μg and in both Groups II and III with 6 ml 0.25% bupivacaine. In the women whose pain score (Visual Analogue Scale) decreased by at least 50% within 15 min, CIEA was given until delivery. The initial infusion rale in all three groups was set at 7 ml · hr−1, but was decreased in the event of motor block or excessive sensory level. For inadequate analgesia, bupivacaine 0.25% in 3 ml supplements was given every 30 min, as required. During the first stage of labour, 88% of women in Group I reported excellent or good analgesia compared with 92% of women in Group II (NS) and with 59% in Group III (P < 0.05). The proportion of women reporting excellent/good analgesia during the second stage was approximately 65% in all three groups. The total cumulative dose of bupivacaine in Group I was 54 ± 36 mg, compared with 107 ± 47 mg for Group II (P = 0.001), and 71 ± 41 mg for Group III (NS). Group I patients required less supplementation with bupivacaine than either Group II or III patients during thefirst stage but only with Group III patients during the second stage. Patients in Group I were less likely to develop motor block than patients in Group II, (P < 0.05). It is concluded that the bupivacaine 0.125% combined with fentanyl (4 μg · ml−1) infusion provided analgesia more effectively than either bupivacaine 0.25% or 0.125% alone during the first stage, or bupivacaine 0.125% alone during the second stage. Continuous infusion epidural analgesia with the bupivacainefentanyl mixture protocol of this study will provide good analgesia during the first stage of labour and adequate analgesia during the second stage, without altering spontaneous delivery rates or neonatal outcomes.