Automated regular boluses for epidural analgesia: a comparison with continuous infusion

Background: Intermittent epidural bolus dosing is a method of drug delivery that can prolong the duration of labour analgesia induced by a combined spinal epidural (CSE). In this randomized, double-blinded study, we compared the analgesic efficacy of two drug delivery systems: regular intermittent epidural boluses and continuous epidural infusion and assessed the incidence of breakthrough pain after CSE. Methods: With the approval of the Hospital Ethics Committee, we recruited 60 parturients into this randomized controlled trial. A CSE was performed with intrathecal fentanyl 25 mu g in all patients. The parturients were then randomly allocated into two groups. The infusion group received a continuous epidural infusion of levobupivacaine 0.1% with fentanyl 2 mu g/mL at a rate of 10 mL/h. The bolus group received 5-mL epidural boluses every half hour. The sample size was computed to detect a 40% reduction in the rate of breakthrough pain. Results: The bolus group had a lower incidence of breakthrough pain than the infusion group (10% vs. 37%, P < 0.05). The bolus group also had significantly higher satisfaction scores for labour analgesia: 97 +/- 8 (mean +/- SD) vs. 89 +/- 7 (P < 0.05). Conclusion: Automated regular bolus delivery of epidural analgesia when compared with continuous infusion decreased the incidence of breakthrough pain and increased maternal satisfaction. In a busy obstetric unit, this may also serve to decrease the anesthetists' workload. (c) 2005 Elsevier Ltd. All rights reserved.