A background infusion of morphine enhances patient-controlled analgesia after cardiac surgery: (Une perfusion de morphine ameliore l'analgesie autocontrolee apres cardiochirurgie).

摘要

PURPOSE: We compared the efficacy of patient-controlled analgesia (PCA), with or without a background infusion of morphine, on postoperative pain relief in patients extubated in the operating room after coronary artery bypass grafting (CABG) surgery. METHODS: With Faculty Ethics approval, 60 consenting adults undergoing elective coronary artery surgery were randomly assigned to receive either morphine PCA alone (group PCA-A, n = 30) or morphine PCA plus a background infusion (group PCA-B, n = 30) for 24 hr postoperatively. Pain scores with verbal rating scale (VRS; from 0 to 10) at rest, sedation scores, morphine consumption and delivery/demand ratios were assessed at zero, one, two, four, six, 12 and 24 hr after surgery. Hemodynamic variables and arterial blood gases were also recorded in the same periods. RESULTS: Sedation scores in the two groups were similar. At all study periods after the first postoperative hour, VRS remained below 5 in both groups. Pain scores were significantly lower in the background infusion group, which also had greater cumulative morphine consumption (61.7 +/- 10.9 mg vs 38.5 +/- 16.2 mg). There were no episodes of hypoxemia or hypertension. CONCLUSION: Morphine PCA effectively controlled postoperative pain after cardiac surgery. The addition of a background infusion of morphine enhanced analgesia and increased morphine consumption.