Continuous interscalene analgesia with ropivacaine 0.2% versus ropivacaine 0.3% after open rotator cuff repair: the effects on postoperative analgesia and motor function.

BACKGROUND Interscalene analgesia is a recognized technique for the management of postoperative pain after major shoulder surgery. The most effective local anesthetic concentration in this setting is still controversial. In this study, we compared the analgesia and side effects of a continuous infusion of ropivacaine 0.2% and 0.3% administered through an interscalene catheter for the first 48 hours after surgery. METHODS Eighty consecutive patients scheduled for elective open rotator cuff repair were randomized into 2 groups to receive a continuous infusion of either ropivacaine 0.2% or ropivacaine 0.3% for 48 hours at a rate of 14 mL/h through an interscalene catheter after a preoperative bolus of 40 mL ropivacaine 0.5% in all patients. Pain score (visual analog scale 0-100), intensity of motor block, quality of sleep during the first postoperative night, morphine consumption, side effects, and patient satisfaction were assessed by an anesthesiologist masked to treatment group. RESULTS Total morphine consumption was significantly reduced in group 0.3% (12 vs 30 mg). Quality of sleep was significantly better in group 0.3% (4% vs 27% of awakening during the first postoperative night). Handgrip strength, visual analog scale scores, and side effects were similar in both groups. CONCLUSION The use of ropivacaine 0.3% through an interscalene catheter for the first 48 hours after open rotator cuff repair provided a significant reduction of morphine consumption and a better sleep quality for the first postoperative night without increasing the intensity of motor block or side effects.