PostoperAtive Neurocognitive Dysfunction After Major AbdomiNal Surgery (PANDAMAN)

The result of 3-minute Diagnostic Interview for Confusion Assessment Method (3D-CAM) is positive.

The Mini-Mental State Examination scale will be used to assist in evaluating preoperative cognitive function in patients. The scale's testing items include orientation, memory, calculation, language, visual space, use, and attention, with a total score of 30. The higher the score, the better the cognitive function, and the score below 27 indicates possible cognitive impairment.

Age-adjusted Charlson Comorbidity Index is a method used to evaluate the impact of multiple diseases on a patient's health status. The scale includes a total of 16 common co-morbidity diseases, which is divided into 4 categories according to different disease severity, with scores of 1,2,3 or 6. The higher the score, the more kinds of diseases the patient suffers at the same time, and their health status may be more complex and fragile.

Hamilton Anxiety Scale will be used to evaluate the patient's anxiety status, which consist of 14 items. All items are scored on a 5-level scale of 0-4, with criteria for each level being none, mild, moderate, severe, and extremely severe. The higher the score, the more severe the anxiety symptoms.

Extract venous blood samples from the target patient, store and centrifuge the Samples appropriately. Quantitatively detect the serum biomakers levels, such as NFL, using enzyme-linked immunosorbent assay, and retest the concentration changes of these biomarkers 3 days after surgery.

Athens Insomnia Scale will be used to assess the patient's preoperative sleep quality. A maximum total score of 24 indicates the most severe symptoms of insomnia, while a cut-off point of ≥6 represents a minimum criterion for the confirmation of insomnia symptoms.

Postoperative pain will be evaluated by Number Rating Scale, which is composed of 11 numbers from 0 to 10, where 0 is no pain or hurt and 10 is the most or worst pain. The higher the number, the more severe the pain.

The length of patient hospital stay will be supplemented through Hospital Information System after surgery.

Short Form 36 Health Survey will be used to estimate the health status and quality of life of patients. This scale includes 8 dimensions and a total of 36 questions, convert the scores of each section into a range of 0 to 100, where 100 represents the "best health state", and the lower the score, the worse the health condition.

Include but limited to hospital readmissions 30 days after surgery, unplaned reoperations, stroke, kidney failure, and wound infections.

The ratio of total deaths from all causes to the population.

The Abbreviated Mental Test Score will be administered by telephone respectively 1 month and 3 months after surgery to identify long-term cognitive consequences of anaesthesia and postoperative delirium. The scale consists of 10 questions with a total of 10 points, the higher the score, the better the cognitive function, and those with score < 8 will be identified as possible neurocognitive dysfunction.