BACKGROUND: The aim of this study was to estimate the effective concentration of subacromial ropivacaine for the control of postoperative pain after arthroscopic shoulder surgery.

METHODS: In a prospective, randomized double-blind trial, 60 patients were divided equally into 3 groups; Groups I, II, and III. At the end of surgery, a bolus dose (0.75% ropivacaine 150 mg, depomedrol 40 mg) was injected via the trocar and a continuous subacromial infusion catheter was inserted into all patients. The drugs were administered for 48 hours after surgery. Group I was given 0.11% ropivacaine in 96 ml of normal saline, which consisted of 0.75% ropivacaine (15 ml), and fentanyl (10 µg/kg). Group II received 0.15% ropivacaine in 96 ml saline consisting of 0.75% ropivacaine (20 ml) and fentanyl, (10 µg/kg). Group III received 0.23% ropivacaine in saline consisting of 0.75% ropivacaine (30 ml) and fentanyl (10 µg/kg). The rate of continuous infusion was, 2 ml/hr. The VAS for pain at rest and the range of motion (ROM) exercise, the amounts of supplemental analgesics and side effects were assessed postoperative 3, 9, 24 and 48 hours.

RESULTS: There was no significant difference in the VAS for pain at rest and ROM exercise as well as in the amounts of supplemental analgesics between the three groups.

CONCLUSIONS: 0.11% ropivacaine with 10 µg/kg fentanyl provides effective postoperative analgesia at rest and during ROM exercise after arthroscopic shoulder surgery.