Continuous subcutaneous infusion of morphine--an alternative to extradural morphine for postoperative pain relief

In a randomized, double-blind study of 40 patients undergoing total abdominal hysterectomy, we have compared continuous subcutaneous infusion (CSCI) of morphine with discontinuous extradural injection of morphine for postoperative analgesia at rest and during cough. The CSCI group received a bolus of morphine 0.1 mg kg-1 i.v. at the end of the operation and continued with s.c. infusion of morphine 30 micrograms kg-1 h-1. The extradural group received morphine 4 mg extradurally at 0, 2, 10 and 18 h after operation. Pain and side effects were evaluated at 2, 4, 8, 12 and 24 h after operation. In the extradural group, significantly smaller pain-scores were observed both at rest and during cough compared with the CSCI group. No significant difference was observed between the groups regarding supplementary doses of morphine, peak expiratory flow values or side effects. We conclude that morphine by CSCI is not as effective as morphine injected extradurally. However, CSCI seems to provide simple and relatively effective analgesia with a low rate of side effects.