The effect of addition of intrathecal clonidine to hyperbaric bupivacaine on postoperative pain and morphine requirements after Caesarean section: a randomized controlled trial

Background. Intrathecal clonidine prolongs spinal anaesthesia.We investigated the effect of the addition of clonidine (75µg) to hyperbaric bupivacaine on postoperative morphineconsumption after Caesarean section in a randomized controlleddouble-blind trial. Methods. A group of 106 women received spinal anaesthesia usingeither bupivacaine 0.5% (2.2 ml) heavy with 0.5 ml normal saline0.9% (B) or bupivacaine 0.5% (2.2 ml) heavy with clonidine (75µg) in 0.5 ml normal saline 0.9% (BC). The primary outcomewas the total morphine consumption in the first 24 h after surgery.Secondary outcomes were the duration of postoperative analgesia,postoperative pain scores, the need for alfentanil during surgery,block regression, clonidine side-effects and morphine side-effects. Results. Total morphine consumption was similar in both studygroups. The mean time to the first analgesic request in theBC group was 129 (SD 13.8) min, compared with 55 (14.2) minin the B group [mean difference (95% CI) –75 (–106to –44) min]. In the BC group 22 (42%) patients had acomplete motor block 1 h after surgery compared with 4 (8%)patients in the B group [RR (95% CI) 0.18 (0.07–0.49)].Side-effects of intrathecal clonidine were not detected. Conclusions. The addition of clonidine (75 µg) to hyperbaricbupivacaine prolongs spinal anaesthesia after Caesarean sectionand improves early analgesia, but does not reduce the postoperativemorphine consumption during the first 24 h. No clinically relevantmaternal or neonatal side-effects were detected.