Motor blockade associated with postoperative analgesia : a comparison between 0.1% ropivacaine plus fentanyl and 0.2% ropivacaine alone for continuous epidural infusion after abdominal hysterectomy

Abstract

Objectives: To compare the motor blockade, analgesia, adverse effects and patient satisfaction between 0.1% ropivacaine plus fentanyl and 0.2% ropivacaine alone for continuous epidural infusion after abdominal hysterectomy.Study design: Randomized controlled trial Setting: Srinagarind Hospital, Faculty of Medicine, Khon Kaen University Research Methodology: Fifty-four women undergoing elective abdominal hysterectomy received continuous epidural block at L1-2 or L 2-3 before the start of general anesthesia. After surgery the patients were randomly allocated into two groups; group R received 0.2% ropivacaine alone, whereas group RF received 0.1% ropivacaine plus fentanyl 2 mcg/ml for continuous epidural infusion at 8 ml/hr. All received patient-controlled analgesia (PCA) using intravenous morphine for additional analgesic as required. Outcome measures included motor blockade (modified Bromage scale), pain intensity (VAS), morphine consumption, level ofsensory blockade as well as any adverse effects. These measures were done at 4, 8 and 21 hour of infusion. At 21 hour the patients were asked about their satisfaction on pain management. Results: The two groups were similar in term of age, body weight, height and site of catheter insertion. However group RF consisted of slightly more patients in ASA status 2, got longer duration of surgery and got additional dose of ropivaciane during surgery. Regarding the rate of motor blockade (adjusted for the difference in baseline characteristics), the lower boundary of 95% CI of the difference at 4 hour (-12.6%) was beyond the magnitude that we can conclude that the two groups were comparable. In contrary, the lower boundary of 95% CI of difference at 8 hours (-3.7%) indicated that group RF was not inferior as compared to group R. At 21 hours group RF had less motor blockade than group R (the lower boundary of 95% CI of difference: 1.8%). There were no differences in VAS, level of sensory blockade, adverse effects andpatient satisfaction between the two groups. Morphine consumption at each time of measurement were comparable but the total amount in group RF was slightly less than group R (12 mg VS 20 mg, p=0.049). Conclusion: At 8 hours, the rate of motor blockade produced by 0.1% ropivacaine plus fentanyl was not inferior as compared to that produced by 0.2% ropivacaine alone. After that, it produced less motor blockade. Though no difference in pain intensity was detected, morphine consumption was slightly lower. Since lower concentration of local anesthetic confers lower risk of toxicity if intravascular migration of epidural catheter occurred, 0.1% ropivacaine plus fentanyl could be a better alternative in postoperative epidural analgesia.