Spread of subarachnoid block, intraoperative local anaesthetic requirements and postoperative analgesic requirements in Caesarean section and total abdominal hysterectomy

Background. Pregnancy is associated with a higher spread ofsubarachnoid anaesthesia and increased pain threshold. The studywas designed to assess the spread of subarachnoid block andthe intra- and postoperative analgesic requirements in pregnantvs non-pregnant women. Methods. We assessed the level of subarachnoid anaesthesia after1.8 ml of hyperbaric lidocaine 5% and the postoperative analgesicrequirements in women undergoing Caesarean section and undergoingabdominal hysterectomy (30 each group). Intraoperatively epiduralropivacaine was given as required. All patients received 10ml of ropivacaine 0.2% epidurally 2, 10, and 24 h after operationand the VAS pain score was assessed. They also had access topatient controlled analgesia i.v. morphine. Results. Duration of surgery was 64 (13.7) vs 127 (33.8) min(P<0.0001) in the pregnant and non-pregnant groups. Ten minutesafter subarachnoid injection, sensory block was higher by threedermatomes in the pregnant group (P<0.0001). Time to firstropivacaine dose was 37 (19.7) vs 19 (12.2) min (P<0.001)and the ropivacaine normalized for the duration of anaesthesiawas 0.8 (0.6) vs 1.3 (0.5) mg^–1 (P=0.001) in the pregnantand non-pregnant groups, respectively. The time between thefirst and second ropivacaine dose was similar in the two groups(P=0.070). Fewer pregnant women (81 vs 100%) required ropivacaineintraoperatively (P=0.017). The VAS scores were similar butparturients consumed more i.v. morphine (33 (14) vs 24 (12)mg, P=0.016) during the first 24 h after operation. Conclusions. Pregnant patients exhibited a higher level of subarachnoidsensory block and required more i.v. morphine after operation.