Reduction of postoperative morbidity following patient-controlled morphine The present study examined the impact of two methods of pain management on recovery in 38 women undergoing hysterectomy. One group received IV morphine in the recovery room and IM morphine on the ward on a PRN basis (PRN group). In the other group, a loading dose of morphine 8 mg IV was given when the patient first complained of pain and patient-controlled IV morphine (PCA) was initiated and continued for 48 h (PCA group). Both groups received similar amounts of morphine overall, differently distributed over time. The PCA patients received 8 mg.h-1 in the recovery room (approximately 2.5 hrs) and less thereafter. The PRN patients received approximately 2 mg.h-1 for the entire 48-hr period. Pain control was better throughout convalescence and less variable across time with PCA management. Minute ventilation also recovered faster and by day four was 25 per cent above the preoperative baseline in the PCA group. In addition, oral temperature became normal one day earlier, ambulation recovered more rapidly and patients were discharged from hospital earlier. The data suggest that early treatment with relatively high, self-titrated morphine doses may alter the course of the metabolic response to surgery. 