Improving patients' postoperative sleep: a randomized control study comparing subcutaneous with intravenous patient-controlled analgesia.

One hundred female patients undergoing major reconstructive plastic or gynaecological surgery were randomized to either receive subcutaneous patient-controlled analgesia (PCA) (bolus dose 2.5 mg diamorphine in 1 ml with a 20-minute lockout) or intravenous PCA (bolus dose 0.5 mg diamorphine in 1 ml with a 5-minute lockout).