Does the addition of morphine to brachial plexus block improve analgesia after shoulder surgery?

We have studied 40 patients undergoing elective shoulder surgery for chronically painful conditions. Patients were allocated randomly to two groups and received interscalene brachial plexus block with 0.5% bupivacaine and adrenaline 1/200,000 40 ml either alone or with the addition of morphine 5 mg. All patients also received a general anaesthetic. The quality of the block, analgesic requirements and any complications or side effects were noted in the intraoperative period and during the 48 h after operation. No significant difference was seen in quality of analgesia or patient satisfaction between the two groups.