Effects of two different anesthesia-analgesia methods on incidence of postoperative delirium in elderly patients undergoing major thoracic and abdominal surgery: study rationale and protocol for a multicenter randomized controlled trial

BACKGROUND: Delirium is a common complication in elderly patients after surgery and associated with increased morbidity and mortality. Studies suggest that deep anesthesia and intense pain are important precipitating factors of postoperative delirium. Neuraxial block is frequently used in combination with general anesthesia for patients undergoing major thoracic and abdominal surgery. Compared with general anesthesia alone and postoperative intravenous analgesia, combined epidural-general anesthesia and postoperative epidural analgesia decreases the requirement of general anesthetics during surgery and provided better pain relief after surgery. However, whether combined epidural-general anesthesia plus epidural analgesia is superior to general anesthesia plus intravenous analgesia in decreasing the incidence of postoperative delirium remains unknown. METHODS/DESIGN: This is a multicenter, open-label, randomized, parallel-controlled clinical trial. One thousand eight hundred elderly patients (age range 60-90 years) who are scheduled to undergo major thoracic or abdominal surgery are randomized to receive either general anesthesia plus postoperative intravenous analgesia or combined epidural-general anesthesia plus postoperative epidural analgesia. The primary outcome is the 7-day incidence of postoperative delirium. Secondary outcomes include the duration of postoperative delirium, the intensity of pain during the first three days after surgery, the 30-day incidences of postoperative non-delirium complications, the length of stay in hospital after surgery and 30-day all-cause mortality. DISCUSSION: Results of the present study will provide information to guide clinical practice in choosing appropriate anesthesia-analgesia method for elderly patients undergoing major thoracic and abdominal surgery. TRIAL REGISTRATION: The study is registered on ClinicalTrials.gov NCT01661907 and Chinese Clinical Trial Registry ChiCTR-TRC-12002371 .