The Effects of Additional Intraoperative Epidural Morphine Bolus Followed by Postoperative Thoracic Epidural Analgesia in Patients Underwent Liver Resection: A Retrospective Study

Abstract

Background: Liver resection is a major surgery that usually causes immense postoperative pain. Thoracic epidural analgesia is one of the effective methods for postoperative pain control. However, inadequate epidural analgesia in liver resection is still high. Objective: To compare the effectiveness of adding a bolus dose of morphine to epidural analgesia with the epidural analgesia alone in patients that underwent liver resection. Materials and Methods: A retrospective study collected the data from medical records of patients aged 18 to 80 who underwent liver resection between October 2018 and March 2021. Patients were divided into two groups, the conventional group and the epidural morphine bolus group that received additional epidural morphine bolus intraoperatively followed by continuous epidural analgesia. The numeric pain rating scale and the requirement for breakthrough pain were collected either at the post-anesthetic care unit (PACU) or on the first postoperative day (POD1) at the ward. The epidural morphine-related side effects were reviewed. Results: One hundred sixty-two patients that underwent liver resection and received thoracic epidural analgesia were reviewed. The eighty-four patients (51.8%) were in the epidural morphine bolus group. The median pain scores at PACU and POD1 in the epidural morphine bolus group and the conventional group were 2.5 (0 to 7) and 6 (1 to 8) (p=0.025), and 1 (1 to 6) and 6 (6 to 7) (p<0.001), respectively. Moreover, the requirement for rescue treatment of the epidural morphine bolus group at both PACU and POD1 was significantly lower than that of the conventional group. However, the incidence of pruritus in the epidural morphine bolus group was significantly higher. Conclusion: Additional epidural morphine bolus into epidural analgesia provided better postoperative pain control and decreased the need for rescue treatment of breakthrough pain compared with the conventional technique. At the same time, the incidence of pruritus was significantly higher in the epidural morphine bolus group