Postoperative hypoxaemia: Continuous extradural infusion of bupivacaine and morphine vs patient-controlled analgesia with intravenous morphine

We carried out a randomized prospective study in 60 patients who had undergone major abdominal surgery for cancer. For postoperative pain control, 30 patients received continuous extradural infusion of 0.125% bupivacaine 12.5 mg h^-1 and morphine 0.25 mg h^-1 (EXI group) and 30 received patient-controlled analgesia (PCA) with intravenous morphine (1 mg bolus, 5-min lock-out and maximum dose 20 mg 4h^-1). Both groups had general anaesthesia. The two groups were compared for postoperative pain scores, satisfaction, sedation and oxygen saturation. Oxygen saturation was recorded continuously the night before surgery and for two consecutive postoperative nights. Episodes of moderate desaturation (90% > Sp(o₂) 85%) were more frequent in the EXI group than in the PCA group (P < 0.05). Pain scores were lower in the EXI group compared with the PCA group at rest and while coughing (P < 0.05). No significant difference was found for patient sedation and satisfaction.