Table 3.

Perioperative risk factors contributing to postoperative delirium

Preoperative factors	Intra- and postoperative factors
Age ≥65 years	Site of surgery (abdominal and cardiothoracic)
Multimorbidities (e.g. cerebrovascular including stroke, cardiovascular, peripheral vascular diseases, diabetes, anemia, Parkinson's disease, depression, chronic pain, and anxiety disorders)	Intraoperative bleeding (blood transfusion of >3 units)
Sensory impairment (hearing/visual loss)	Long duration of surgery
Higher American Society of Anesthesiologists’ physical status classification system or the Charlson Comorbidity Index (CCI) or the Clinical Impairment Assessment	Excessive pain
Score (CIAS) before surgery
Frailty (malnutrition, hypoalbuminemia, hypercholesterolemia, high levels of inflammation, muscular atrophy, etc.)	Emergency surgery
Prolonged preoperative fluid fasting and dehydration	Postoperative complications
Hyponatremia/hypernatremia	Hyperthermia/Hypothermia
Anticholinergics
Alcohol-related disorders/alcohol use disorders/substance abuse
Cognitive impairment