Continuous wound infusion with local anaesthetic has been used in post-caesarean pain management with conflicting results. We carried out a study comparing three groups: continuous ropivacaine wound infusion, intrathecal morphine with saline wound infusion and saline wound infusion only.
Sixty-six women undergoing elective caesarean section under combined spinal-epidural anaesthesia were randomly allocated to receive intrathecal morphine with saline wound infusion or 48 h continuous wound infusion with either ropivacaine or saline. All parturients received oral ketoprofen and intravenous oxycodone patient-controlled analgesia. Consumption of oxycodone, visual analogue scale pain scores (0-10 cm), patient satisfaction, side effects and recovery parameters were recorded for 48 h in a double-blind manner.
Continuous wound infusion with ropivacaine failed to reduce oxycodone consumption or pain scores compared with saline control. In the first 24 h intrathecal morphine reduced mean oxycodone consumption compared to the ropivacaine wound infusion group (26 mg vs. 48 mg, P=0.007) and saline wound infusion group (26 mg vs. 45 mg, P=0.021). The first 24-h mean pain score was also lower in the intrathecal morphine group vs. the saline wound infusion group (1.3 vs. 2.2, P=0.021). Pain scores were not significantly different between intrathecal morphine and ropivacaine wound infusion groups. Pruritus was more common with intrathecal morphine.
Compared to saline control, continuous wound infusion with ropivacaine failed to reduce the use of intravenous oxycodone patient-controlled analgesia or pain scores. Intrathecal morphine decreased oxycodone consumption by 46% in the first 24 h after surgery when compared to continuous ropivacaine wound infusion.