Background: Epidural analgesia is the recommended analgesic technique in patients having surgery with moderate to severe
postoperative pain. Inadequate pain control in patients receiving epidural analgesia frequently occurred in clinical practice but the number of the success rate or the failure rate have not been reported in our university hospital.
Objective: The aim of the prospective descriptive study is to examine various data related to and evaluate the effectiveness of the postoperative epidural analgesia in Siriraj Hospital, a university hospital in Thailand.
Material and Method: Patients scheduled to have elective thoracic or abdominal surgery under general anesthesia combined with epidural analgesia from December 2014 to October 2015 were enrolled in this study. Three hundred and sixty-four patients were finally analyzed. All data about demographics, surgery, epidural techniques, postoperative pain scores at rest and on movement, and postoperative complications were collected.
Results: The number of patients having acceptable postoperative pain score at rest at all time period was 51.4%, (95% CI 46.3-56.5). Fifty patients (13.7%) in this group needed intravenous rescue medication for breakthrough pain. The incidence of severe postoperative pain at rest during running of epidural medication was 24.5% (95% CI 20.3-29.1). One hundred patients (27.5%) experienced postoperative nausea and vomiting; and 28 patients (7.7%) had episodes of hypotension. The incidences of accidental dural puncture and post-dural puncture headache were 1.36% and 0.8%, respectively.
Conclusion: Inadequate postoperative analgesia with epidural technique occurred in up to 50% of patients in this study in
which the rescue pain medication was necessary. In-depth analysis to identify associated factors to improve the effectiveness of postoperative epidural analgesia should be further investigated.

Keywords: Epidural analgesia, Postoperative pain, Pain management