The effect of dexmedetomidine combined with transcutaneous auricular vagus nerve stimulation on postoperative delirium in elderly patients: A randomized controlled trial

INTERVENTION: Dexmedetomidine combined with taVNS group:Dexmedetomidine anaesthesia was maintained during the operation, taVNS was started 5 minutes after anaesthesia induction and continued for 30 minutes, and taVNS was continued for 30 minutes postoperatively;Dexmedetomidine group:Intraoperative maintenance of anaesthesia with dexmedetomidine; CONDITION: Postoperative delirium PRIMARY OUTCOME: Incidence of postoperative delirium; SECONDARY OUTCOME: Heart rate variability analysis;Postoperative pain score;Sleep quality score;Postoperative anxiety score;Postoperative depression score ;Inflammatory cytokines;Intraoperative vasoactive drug dosage;Opioid consumption;Number of patients requiring rescue analgesia;Any postoperative adverse events; INCLUSION CRITERIA: 1. Perform elective non‐cardiac surgery under general anesthesia, with operation time >=2 hours and <=5 hours. 2. Age >=65 years old. 3. ASA grade I to III. 4. BMI <=30 kg/m². 5. Preoperative cognitive function: MMSE score > 20.