Use of dexmedetomidine during light versus deep anaesthesia on postoperative delirium among elderly patients undergoing major non-cardiac surgery: protocol for a multicentre randomised factorial trial

Introduction: Elderly patients are at a high risk of postoperative delirium (POD), leading to increased postoperative morbidity and mortality. The use of dexmedetomidine and depth of anaesthesia may influence POD. This study aims to determine the effects of dexmedetomidine infusion versus normal saline placebo during light versus deep anaesthesia on POD among elderly patients undergoing major non-cardiac surgery.

Methods and analysis: This prospective, multicentre, randomised, controlled, factorial trial will be conducted at three tertiary hospitals in Jiangsu, China. We will recruit a total of 420 patients who are at least 60 years old and undergoing major non-cardiac surgery (thoracic, abdominal, urology, orthopaedic and spine surgery) under general anaesthesia. Patients will be randomised (1:1:1:1) to receive one of four anaesthesia regimens: (1) dexmedetomidine and light anaesthesia, (2) dexmedetomidine and deep anaesthesia, (3) placebo and light anaesthesia or (4) placebo and deep anaesthesia. Dexmedetomidine will be infused at 0.5 µg/kg/h throughout surgery, and intraoperative bispectral index target will be 55 for light anaesthesia and 40 for deep anaesthesia. The primary outcome is the occurrence of POD during the first 7 days postoperatively or until hospital discharge, assessed using the 3-min Confusion Assessment Method two times per day. The secondary outcomes include days with POD, type of POD, pain scores at rest and on movement at 24 and 48 hours postoperatively, patient-controlled intravenous fentanyl consumption during 0-24 and 24-48 hours postoperatively, hypotension, bradycardia, postoperative nausea and vomiting, non-delirium complications, length of postoperative hospital stay, 30-day cognitive function and 30-day mortality. Data will be analysed on a modified intention-to-treat basis.

Ethics and dissemination: This trial was approved by the Ethics Committee of the First Affiliated Hospital of Soochow University and each participating centre. The trial results will be published in a peer-reviewed journal.

Trial registration: Chinese Clinical Trial Registry (ChiCTR2300073271).