Effect of desflurane, sevoflurane or propofol on the incidence of postoperative delirium in older adults undergoing moderate- to high-risk major non-cardiac surgery: study protocol for a prospective, randomised, observer-blinded, clinical trial (RAPID-II trial).

introductionThe effect of different anaesthetics on the incidence of postoperative delirium is still not entirely clear. Therefore, we will evaluate the effect of desflurane versus sevoflurane versus propofol for the maintenance of anaesthesia on the incidence of postoperative delirium in older adults undergoing moderate- to high-risk major non-cardiac surgery. We will further compare the incidences of delayed neurocognitive recovery, long-term postoperative neurocognitive disorder, postoperative nausea and vomiting between the groups. METHODS AND ANALYSIS: In this multicentre, prospective, observer-blinded, randomised controlled clinical trial, we will include 1332 patients ≥65 years of age undergoing moderate- to high-risk major non-cardiac surgery lasting at least 2 hours. Patients will be randomly 1:1:1 assigned to receive desflurane, sevoflurane or propofol for anaesthesia. Maintenance of anaesthesia will be performed in a goal-directed manner using processed electroencephalography with an intraoperative goal of bispectral index 40-60. Our primary outcome will be the incidence of postoperative delirium within the first five postoperative days. Postoperative delirium will be assessed using the three-dimensional-confusion assessment method (3D-CAM) or CAM-intensive care unit (ICU) in the morning and evening of the first five postoperative days by blinded study personnel. The primary outcome, the incidence of postoperative delirium, will be compared between the three study groups using a χ ETHICS AND DISSEMINATION: This clinical trial has been approved by the ethics committee and the Federal Office for Safety in Healthcare as the competent authority for clinical trials in Austria. The results of this trial will be published in a peer-reviewed journal. TRIAL REGISTRATION NUMBER: ClinicalTrials.gov NCT05990790.