Onset of labor epidural analgesia with ropivacaine and a varying dose of fentanyl: a randomized controlled trial

Background: This study was conducted to investigate the onset of labor epidural analgesia using 0.17% ropivacaine with a varying dose of fentanyl. We hypothesized that the onset of analgesia would be shortened in proportion to an increase in fentanyl dose. Methods: Women requesting labor epidural analgesia were enrolled in this randomized controlled clinical trial. Each woman was randomly assigned to receive fentanyl 0, 50, 75, or 100 mu g with 0.17% ropivacaine 12 mL. The onset and duration of analgesia, the incidence of side effects and patient satisfaction were measured. Results: Data from 102 women were analyzed. The onset of analgesia (mean +/- SD) was shortened with an increasing dose of fentanyl (14.3 +/- 5.4, 14.2 +/- 6.5, 12.1 +/- 5.1, and 8.7 +/- 3.8 min with fentanyl 0, 50, 75, or 100 mu g, respectively, P = 0.001). The duration of analgesia was prolonged with an increasing dose of fentanyl (87.4 +/- 20.8, 112.3 +/- 19.5, 140.8 +/- 18.8, and 143.6 +/- 18.6 min with fentanyl 0, 50, 75, or 100 mu g, respectively, P < 0.001). The incidence of pruritus increased with an increasing dose of fentanyl (P = 0.027) but there were no differences for other maternal side effects. There was a significant difference in satisfaction score among groups (P = 0.009). Conclusion: The addition of increasing doses of fentanyl to 0.17% ropivacaine contributed to shortened onset as well as prolonged duration of labor epidural analgesia and improved patient satisfaction. (C) 2011 Elsevier Ltd. All rights reserved.