Hypoxaemia and pain relief after upper abdominal surgery: comparison of i.m. and patient-controlled analgesia.

Abstract

Forty patients recovering from upper abdominal surgery were allocated randomly to receive i.m. morphine 0.15 mg kg-1 as required or patient-controlled analgesia (PCA), with i.v. morphine 1 mg and a 5-min lock out time. Arterial oxygen saturation (SpO2) was measured continuously the night before and for 24 h immediately after surgery. A significantly greater proportion of patients in the PCA group (nine of 19) rated their analgesia as excellent compared with the i.m. group (two of 20) (P < 0.05). There was no significant difference in the incidence of postoperative hypoxaemia in the two treatment groups. Severe postoperative hypoxaemia (SpO2 < 85% for more than 6 min h-1) was seen in three patients receiving i.m. analgesia and one patient in the PCA group.