The case for patient-controlled analgesia. Inter-patient variation in postoperative analgesic requirements.

Postoperative morphine requirements were assessed for the first 48 hours after surgery in 93 consecutive patients undergoing elective or emergency laparotomies. Analgesia was provided by patient-controlled analgesic (PCA) pumps. Daily morphine utilisation was recorded. At the conclusion of PCA therapy, patients were asked to assess their quality of analgesia. Eighty-one patients, who reported good or excellent pain relief, were included in the study. Data are presented demonstrating the wide variation in morphine requirements necessary to produce this level of analgesia.