Comparison of ropivacaine with and without fentanyl vs bupivacaine with fentanyl for postoperative epidural analgesia in bilateral total knee replacement surgery.

STUDY OBJECTIVES: Pain after total knee replacement (TKR) interferes with early rehabilitation. Although the use of epidural bupivacaine in post-TKR patients is associated with effective analgesia, the associated motor blockade effect delays functional recovery. We compared analgesic efficacy and side effects of postoperative patient-controlled epidural analgesia (PCEA) with plain ropivacaine 0.1% with/without fentanyl 2.5 µg/mL vs plain bupivacaine 0.0625% with fentanyl 2.5 µg/mL in patients undergoing bilateral TKR. DESIGN: Prospective, double-blind, randomized study. SETTINGS: Operation room, postoperative recovery room, and intensive joint replacement unit. PATIENTS: Ninety American Society of Anesthesiologists I to II post-TKR patients who were randomly allocated to receive postoperative PCEA with plain ropivacaine 0.1% (group 1), ropivacaine 0.1% with fentanyl 2.5 µg/mL (group 2), and plain bupivacaine 0.0625% with fentanyl 2.5 µg/mL (group 3). INTERVENTION: Postoperatively, the PCEA settings were standardized for a basal flow of 4 mL/h, demand dose of 6 mL, and lock-out interval of 20 minutes. "Rescue" analgesia included epidural boluses (6 mL) of respective study drug over and above PCEA administration. MEASUREMENTS: Postoperative pain profile, total PCEA drug used, heart rate, and noninvasive blood pressure, side effects, and patient satisfaction were recorded. MAIN RESULTS: Demographic parameters, duration of surgery, and hemodynamic variables (heart rate and noninvasive blood pressure) were comparable for the 3 study groups. Pain scores and rescue drug requirements were greater in "ropivacaine-only" group. Motor blockade was greatest in "bupivacaine-fentanyl" group. Postoperatively, despite the presence of minor side effects (nausea, itching) in the "ropivacaine-fentanyl" and bupivacaine-fentanyl groups, the patients belonging to these groups were more satisfied. CONCLUSION: After bilateral TKR, ropivacaine-fentanyl combination administered through a PCEA system resulted in "superior" analgesic efficacy, that is, pain relief without motor blockade, than "ropivacaine alone" (lesser pain relief) and bupivacaine-fentanyl (pain relief but with attendant motor blockade). Overall, the addition of fentanyl to epidural local anesthetic returned favorable postoperative analgesia profile and patient satisfaction with minor incidence of opioid-related side effects.