Neurocognitive complications, mainly delirium and neurocognitive disorders, are common cerebral complications in older patients after surgery and associated with worse outcomes. In previous studies, perioperative use of dexmedetomidine-esketamine combination improved analgesia and sleep quality after surgery. Perioperative use of transcranial direct current stimulation (tDCS) also improved sleep quality and reduced delirium occurrence early after surgery. This 2×2 factorial trial is designed to investigate the effects of perioperative dexmedetomidine-esketamine combination and tDCS on early postoperative neurocognitive recovery and delirium occurrence in older patients.
Aged 65 to 90 years;
Preoperative Mini-Mental State Examination (MMSE) score < 27 points, indicating possible cognitive impairment ranging from mild to moderate;
Scheduled to undergo elective non-cardiac, non-neurosurgical surgery under general anesthesia, with an expected surgical duration > 1 hour;
Required patient-controlled intravenous analgesia (PCIA) after surgery.
Preoperative inability to communicate due to coma, severe dementia, end-stage disease, or language impairment;
History of schizophrenia, epilepsy, Parkinson's disease, brain trauma/surgery, or myasthenia gravis;
Presence of metal implants in the intracranial or cervical region (such as cochlear implants, aneurysm clips, deep brain stimulation electrodes), or skin damage or severe skin disease on the head;
Severe cardiac dysfunction (left ventricular ejection fraction < 30%), comorbid with sick sinus syndrome, severe bradycardia (heart rate < 50 bpm), or second-degree or higher atrioventricular block, or implantation of a cardiac pacemaker;
Factorial
Dex-Esk
DrugDexmedetomidine-esketamine combination (1 μg/mL dexmedetomidine and 0.5 mg/mL esketamine) will be administered after anesthesia induction, firstly as a loading dose at a rate of \[0.4 x body weight (kg)\] mL/h for 30 minutes (0.2 μg/kg dexmedetomidine and 0.1 mg/kg esketamine), followed by a maintenance infusion at a rate of \[0.1 x body weight (kg)\] mL/h (0.1 μg/kg/h dexmedetomidine and 0.05 mg/kg/h esketamine) until one hour before the expected end of surgery. Postoperative patient-controlled analgesia will be established with a 100 mL mixture (containing 1.0 μg/mL sufentanil, 1.25 μg/mL dexmedetomidine, and 0.25 mg/mL esketamine in normal saline), programmed to deliver 2-mL boluses with an 8-minute lockout interval and an 1-mL/h background infusion, and provided for 48 hours (at least 24 hours).
Placebo
DrugPlacebo (normal saline) will be administered after anesthesia induction, firstly as a loading dose at a rate of \[0.4 x body weight (kg)\] mL/h for 30 minutes, followed by a maintenance infusion at a rate of \[0.1 x body weight (kg)\] mL/h until one hour before the expected end of surgery. Postoperative patient-controlled analgesia will be established with a 100 mL mixture (containing 1.0 μg/mL sufentanil in normal saline), programmed to deliver 2-mL boluses with an 8-minute lockout interval and an 1-mL/h background infusion, and provided for 48 hours (at least 24 hours).
Active tDCS
DeviceActive transcranial direct current stimulation (tDCS) will be administered using a battery-powered stimulator. The anode will be positioned over the left dorsolateral prefrontal cortex (DLPFC, F3) and the cathode over the right supraorbital region (Fp2). The stimulation intensity will be set at 2.0 mA, featuring a 30-second linear ramp-up at the beginning and a 30-second ramp-down at the end of each session. Each participant will receive a total of three 20-minute sessions of active tDCS. The first session will be provided at 40 minutes after extubation in the post-anesthesia care unit. Two other sessions will be provided on postoperative days 1 and 2 (between 10:00 and 12:00 am).
Sham tDCS
DeviceSham transcranial direct current stimulation (tDCS) will be administered using a battery-powered stimulator. The anode will be positioned over the left dorsolateral prefrontal cortex (DLPFC, F3) and the cathode over the right supraorbital region (Fp2). To ensure blinding, the device will deliver a initial 30-second ramp-up to 2.0 mA followed immediately by a 30-second ramp-down to 0 mA. The device remains "ON" for the remaining 19 minutes with no effective current output, mimicking the peripheral scalp sensation without delivering cortical modulation. Each participant will receive a total of three 20-minute sessions of sham tDCS. The first session will be provided at 40 minutes after extubation in the post-anesthesia care unit. Two other sessions will be provided on postoperative days 1 and 2 (between 10:00 and 12:00 am).
Incidence of delayed neurocognitive recovery (dNCR)
Cognitive function will be assessed at baseline and at 5 days after surgery (or before hospital discharge) using the Montreal Cognitive Assessment (MoCA; scores range from 0 to 30, with higher scores indicating better cognitive function). Delayed neurocognitive decline (dNCR) is defined as: a \|Z\| value of decline in MoCA score ≥1.96. Z value = \[(change from baseline in MoCA score in a surgical patient - mean change from baseline in MoCA score in the non-surgical group)\] / (standard deviation of change from baseline in MoCA score in the non-surgical group).
Incidence of postoperative delirium
Delirium will be assessed twice daily (8-10 am and 6-8 pm) using the 3-Dimensional Confusion Assessment Method (3D-CAM) for patients without intubation or the Confusion Assessment Method for the Intensive Care Unit (CAM-ICU) for patients with intubation.
Incidence of postoperative neurocognitive disorders (pNCD)
Cognitive function will be assessed at baseline and at 30 days after surgery using the Montreal Cognitive Assessment (MoCA; scores range from 0 to 30, with higher scores indicating better cognitive function). Postoperative neurocognitive disorders (pNCD) is defined as: a \|Z\| value of decline in MoCA score ≥1.96. Z value = \[(change from baseline in MoCA score in a surgical patient - mean change from baseline in MoCA score in the non-surgical group)\] / (standard deviation of change from baseline in MoCA score in the non-surgical group).
Early postoperative pain intensity
Pain intensity will be assessed twice daily (8-10 am and 6-8 pm) both at rest and with movement (coughing or turning over) using an 11-point Numeric Rating Scale (NRS; scores range from 0 to 10 where 0=no pain and 10=the worst pain). Pain intensity early after surgery will be summarized as the area under the curve (AUC) using the trapezoidal method.
Early postoperative subjective sleep quality
Subjective sleep quality will be assessed once daily (8-10 am) using an 11-point Numeric Rating Scale (NRS; scores range from 0 to 10 where 0=the best sleep and 10=the worst sleep. Subjective sleep quality early after surgery will be summarized as the cumulative score of subjective sleep quality during the first 4 postoperative nights.
Length of hospital stay (LOS) after surgery
From the day of surgery until the day of hospital discharge.
Incidence of postoperative complications within 30 days
Postoperative complications are defined as new-onset conditions that are deemed harmful and required therapeutic intervention, i.e., grade II or above on the Clavien-Dindo classification.
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Peking University First Hospital
Lead sponsor
Peking University Shenzhen Hospital
Collaborator
The First Affiliated Hospital of Air Force Medicial University
Collaborator
Zhejiang University
Collaborator
Second Affiliated Hospital, School of Medicine, Zhejiang University
Collaborator
Fujian Medical University Union Hospital
Collaborator
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