Continuous subcutaneous infusion of morphine for postoperative pain relief

A double-blind randomised study of 48 patients in whom continuous subcutaneous infusion and regular intramuscular injection of morphine were compared as analgesic regimens after upper abdominal surgery, is described. Over a 48-hour period, no difference in pain intensity between the two groups was found by comparing linear analogue scores, assessments on a four-point rank scale, peak expiratory flow rates or requirement for additional analgesia. Nausea and sedation were assessed using a four-point rank scale. These side effects were less frequent with subcutaneous infusion (p less than 0.05). Two patients from each group were judged to have received an overdose. The infusion apparatus was simple and convenient to use. Continuous subcutaneous infusion of morphine is a practical and effective means of achieving post-operative analgesia but, as with other mandatory dosing regimens, relative overdosage may occur.