A comparison of ropivacaine with fentanyl to bupivacaine with fentanyl for postoperative patient-controlled epidural analgesia

Ropivacaine for patient-controlled epidural analgesia (PCEA) may facilitate postoperative patient mobilization because it causes less motor block than bupivacaine. Forty patients undergoing abdominal surgery were randomized in a double-blinded manner to the following: 0.05% bupivacaine/4 mug fentanyl, 0.1% bupivacaine/fentanyl, 0.05% ropivacaine/fentanyl, or 0.1% ropivacaine/fentanyl for standardized PCEA. We measured pain scores, side effects, and PCEA consumption for 42 h. Lower-extremity motor function was assessed with electromyography and isometric force dynamometry. Analgesia was equivalent among groups. Local anesthetic use was more in the 0.1% Ropivacaine and 0.1% Bupivacaine groups (77% increase, P = 0.001). Motor function decreased during PCEA (10%-35% decrease from preoperative, P < 0.001) and was equivalent among groups. Eight patients were transiently unable to ambulate. These patients used more local anesthetic (45 vs 33 mg mean, P < 0.05) with additional decrease in motor function (32%, P < 0.004) compared with ambulating patients. Other side effects were mild and equivalent among solutions. PCEA with bupivacaine/fentanyl and ropivacaine/fentanyl as 0.05% or 0.1% solutions appears clinically equipotent. Lower-extremity motor function decreases, but is unlikely to result in prolonged inability to ambulate. Use of a 0.05% solution may be advantageous to decrease local anesthetic use and prevent transient motor block.