The Effects of Subanesthetic S-ketamine on Postoperative Delirium and Cognitive Function in the Elderly Undergoing Non-cardiac Thoracic Surgery

Study Overview
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Brief Summary
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Postoperative delirium (POD) is a common and distressing complication after thoracic surgery. S-ketamine has neuroprotective properties as a dissociative anesthetic. Emerging literature has indicated that S-ketamine can reduce cognitive impairment in depressed patients. However, the role of S-ketamine in preventing postoperative delirium is still unknown. Therefore, this study aims to evaluate the effect of intraoperatively prophylactic S-ketamine compared to dexmedetomidine on the incidence of postoperative delirium in elderly patients undergoing non-cardiac thoracic surgery.

Detailed Description
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Postoperative delirium (POD) is a common and distressing complication after thoracic surgery. S-ketamine has neuroprotective properties as a dissociative anesthetic. Emerging literature has indicated that S-ketamine can reduce cognitive impairment in depressed patients. However, the role of S-ketamine in preventing postoperative delirium is still unknown. Therefore, this study aims to evaluate the effect of intraoperatively prophylactic S-ketamine compared to dexmedetomidine on the incidence of postoperative delirium in elderly patients undergoing non-cardiac thoracic surgery. This will be a randomized, double-blinded, placebo-and positive-controlled, non-inferiority trial that enrolls patients aged 60 or over undergoing thoracic surgery. The primary outcome will be the incidence of postoperative delirium within 4 days after surgery and assessed using a 3-minute Diagnostic Confusion Assessment Method (3D-CAM) twice a day. The main secondary outcomes will be the severity and duration of postoperative delirium. Other prespecified secondary outcomes will be the incidence of emergency delirium, postoperative pain, quality of sleep, cognitive function, and the plasm concentration of acetylcholine, brain-derived neurotrophic factor, and tumor necrosis factor.

Official Title
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The Effects of Subanesthetic S-ketamine on Postoperative Delirium and Cognitive Function in the Elderly Undergoing Non-cardiac Thoracic Surgery: a Protocol for Randomized, Double-blinded, placebo-and Positive-controlled, Non-inferiority Trial

Conditions
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Postoperative Delirium, Elderly Patients

Intervention / Treatment
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* Drug: S-ketamine
* Drug: Dexmedetomidine
* Drug: Normal saline


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Aged 60 years or over Both genders American anesthesiologist association (ASA) physical status classificationⅠ-Ⅲ Diagnosed with lung, esophagus, or mediastinum disorders Undergoing open or video-assisted thoracic surgery including lobectomy, segmentectomy, pneumonectomy, esophagectomy, or resection of mediastinal tumor General anesthesia with one-lung ventilation (OLV) or bronchial blocker. An expected operation duration of 2 hours or more. Voluntarily participate in the trial and sign informed consent. Exclusion Criteria: History of psychiatric disease or severe depression History of glaucoma or hyperthyroidism History of severe hepatic (Child-Pugh grade C) or renal (requirement for renal replacement therapy) disorder. Body mass index (BMI) greater 35 kg/m2 Dementia history or baseline Mini-Mental State Examination (MMSE) score less than 23 Severe audio-visual impairments, or inability to speak Mandarin or Cantonese precluding communication Sinus bradycardia (heart rate < 50 beats per minutes, bpm), sick sinus or Wolff- Parkinson-White syndromes, or Ⅱ degree atrioventricular block and over Poorly controlled hypertension (resting systolic blood pressure over 180 mm Hg, or resting diastolic blood pressure over 100 mm Hg) Allergic to dexmedetomidine, S-ketamine or any of their formulation ingredients; Taking sedatives, antidepressants or glucocorticoids Alcohol or drug abuser Life expectancy of less than 2 months due to extensive tumor metastasis.

Ages Eligible for Study
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Minimum Age: 60 Years
Maximum Age: 90 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Prevention
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Quadruple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: S-ketamine<br>S-ketamine (50 mg, 2 ml) is diluted to 50 ml (1 mg/ml) with 48 ml normal saline; | Drug: S-ketamine<br>* Loading dose: 0.25mg/kg in 10 minutes Maintenance dose: 0.1mg/kg/h<br>|
| Active Comparator: Dexmedetomidine<br>Dexmedetomidine (200 ug, 2 ml) is diluted to 100 ml (2 ug/ml) with 98 ml normal saline; | Drug: Dexmedetomidine<br>* Loading dose: 0.2 ug/kg in 10 minutes Maintenance dose: 0.2 ug/kg/h<br>|
| Placebo Comparator: Normal saline<br>Control group only contains 50 ml normal saline in light of blindness | Drug: Normal saline<br>* Refer to either S-ketamine or Dexmedetomidine<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Number of Patients With Post-operative Delirium in 4 Days After Surgery | 3-minute Diagnostic Confusion Assessment Method (3D-CAM) | Within 4 days after surgery | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Severity of Delirium | Confusion Assessment Method- Severity (CAM-S, Mild-to-moderate delirium will be defined as a CAM-S score of 3 to 5, while severe delirium will be defined as a CAM-S score of 6 to 7) | Within 4 days after surgery | 
| Duration of postoperative delirium | Positive days of postoperative delirium | Within 4 days after surgery | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Postoperative delirium, S-ketamine, Dexmedetomidine, elderly patients