Table 1.

Delirium Risk Factors

Critically ill patients are exposed to a multitude of risk factors for delirium relating to baseline comorbidities, acute illness and treatment in the hospital/ICU. These risk factors may be viewed as unmodifiable/unpreventable or potentially modifiable/preventable. Delirium prevention in the ICU should focus on reducing the number and duration of potentially modifiable/preventable risk factors.

	Unmodifiable/ Unpreventable Risk Factors	Potentially Modifiable/ Preventable Risk Factors
Baseline Risk Factors	Age
	APOE-4 genotype
	History of Hypertension
	Pre-existing cognitive impairment	Sensory depravation (i.e., Hearing or Vision Impairment)
	History of Alcohol Use
	History of Tobacco Use
	History of Depression
Acute Illness-Related Risk Factors	High Severity of Illness	Anemia
	Respiratory Disease	Acidosis
	Medical Illness (vs. Surgical)	Hypotension
	Need for mechanical ventilation	Infection/Sepsis
	Number of infusing medications	Metabolic disturbances (e.g. hypocalcemia, hyponatremia, azotemia, transaminitis, hyperamylasemia, hyperbilirubinemia)
	Elevated inflammatory biomarkers
	High LNAA metabolite levels	Fever
Hospital-Related Risk Factors		Lack of visitors
		Sedatives/Analgesics (e.g. benzodiazipines and opiates)
	Lack of daylight	Immobility
	Isolation	Bladder catheters
		Vascular catheters
		Gastric tubes
		Sleep depravation

APOE-4: apolipoprotien-E4 polymorphism; CRP: C-reactive protein; LNAA: Large neutral amino acids