Morphine versus fentanyl patient-controlled analgesia for postoperative pain control in major hepatic resection surgeries including living liver donors: A retrospective study

BACKGROUND: Liver resection surgery results in significant postoperative pain. However, it is still not clear which opioids used by patient-controlled analgesia (PCA) provides the best pain control and results in the least side effect in a patient with impaired liver function. Our hypothesis was that fentanyl is a better choice than morphine as it is a potent analgesic that its elimination half-life does not depend on the hepatic uptake and metabolism. THE STUDY PURPOSE: Is to compare morphine and fentanyl PCA in liver resection patients as regards the degree of pain control, the consumption of opioids, and the side effects. METHODS: A retrospective case–control study of hepatic resection patients who received postoperative morphine (Morph) or fentanyl (Fent) PCA. The study compared the pain scores, the morphine equivalent dose (MED), the number of demands requested as recorded by the PCA infusion pump, and the side effects every 12 h for 48 h. RESULTS: This study yielded 40 patients; with the majority were living donor hepatic resection patients. There was no significant difference in the pain scores. However, the MED and the demands were significantly less in the Morph group. The P < 0.000, 0.0001, 0.0005, and 0.003, demands P < 0.002, 0.006, 0.014, and 0.013 at 12, 24, 48, and 36 h, respectively. The overall side effects were not different between the 2 groups at all time intervals measured; however, Morph patients were significantly more sedated in the first 12 h. There was one case of respiratory depression in the Morph group compared to two cases in the in the Fent group that needed treatment with naloxone. CONCLUSIONS: Although both groups had adequate pain control. The Morphine group reached faster pain control with less MED and PCA requests in liver resection patients, although it was more sedating in the first 12 h. However, fentanyl patients were less sedated; both drugs need close monitoring in the immediate postoperative period due to reported respiratory depressive effect and the need to use naloxone. The dosage of the PCA settings needs to be studied further to reach to the best dose with a reduced side effect. Further studies are recommended to reduce PCA dosages by introducing a multimodal approach of pain management relying on other methods with no additional sedative effects as regional anterior abdominal blocks.