Postoperative delirium: A tragedy for elderly cancer patients

Table 1 Definition of delirium by the Diagnostic and Statistical Manual of Mental Disorders, 5^th edition[1]

Diagnostic criteria
A disturbance in attention (i.e. reduced ability to direct, focus, sustain, and shift attention) and awareness (reduced orientation to the environment)
The disturbance develops over a short period of time (usually hours to a few days), represents a change from baseline attention and awareness, and tends to fluctuate in severity during the course of a day
An additional disturbance in cognition (e.g., memory deficit, disorientation, language, visuospatial ability, or perception)
The disturbances in criteria A and C are not better explained by another preexisting, established, or evolving neurocognitive disorder and do not occur in the context of a severely reduced level of arousal, such as coma
There is evidence from the history, physical examination, or laboratory findings that the disturbance is a direct physiological consequence of another medical condition, substance intoxication or withdrawal (i.e. due to a drug of abuse or to a medication), or exposure to a toxin, or is due to multiple etiologies

Table 2 Factors associated with the risk of postoperative delirium[4]

Predisposing factors	Precipitating factors
Advanced age	Preoperative preparation: (1) Long-duration of fluid fasting; and (2) Preoperative pain
Lower educational level	Perioperative medication: (1) Anticholinergic drugs; (2) Benzodiazepines; (3) Opioid use; and (4) Use of pethidine
Functional status: (1) Cognitive impairment; (2) Hearing impairment; and (3) Frailty	Intraoperative factors/management: (1) Deep anesthesia; (2) Intraoperative blood loss/ blood transfusion; (3) Cerebral oxygen desaturation; (4) Hypotension; and (5) Hypothermia
Comorbidities: (1) Depression; (2) Psychiatric illness; (3) Cerebrovascular disease; (4) Parkinsonism; (5) Heart failure; (6) Hypertension; (7) Mitral valve disease; (8) Diabetes; (9) Obstructive sleep; (10) Pulmonary disease; (11) Kidney disease; and (12) Number of medications	Surgical management: (1) Abdominal/orthopedic surgery; (2) Higher surgical Apgar score; and (3) Long-duration surgery
Comorbidity scores: (1) Higher ASA grade; (2) NYHA functional class III/IV; (3) Higher EuroSCORE; and (4) Higher Charlson comorbidity index	Postoperative management: (1) Severe pain; (2) Long-duration mechanical ventilation; and (3) Prolonged stay in intensive care unit
Alcohol abuse
Nutritional status: (1) Malnutritional/low albumin; (2) Low preoperative hematocrit; and (3) Vitamin D deficiency

EuroSCORE: European system for cardiac operative risk evaluation; NYHA: New York Heart Association.

Table 3 European Society of Anesthesiology and Intensive Care recommendations regarding the risk of postoperative delirium in elderly patients[29]

Recommendation	Quality of evidence	Strength of recommend
We recommend evaluating the following preoperative risk factors for POD: Older age, American Society of Anesthesiology Physical status score > 2, Charlson comorbidity index > 2, and Mini-Mental State Examination score lower than 25 points	Moderate	Strong
We do not suggest any specific type of surgery or type of anesthesia to reduce the incidence of POD	Low	Weak
When dexmedetomidine is used intra-operatively or postoperatively with the aim to prevent POD, we recommend balancing the expected benefits against the most important side effects (bradycardia and hypotension)	Moderate	Strong
We recommend that preoperative anesthesia consultation in older adults includes the screening for risk factors for POD and addresses patients’ needs to optimize their preoperative status	Low	Strong
We recommend that the results of the screening for POD risk factors are shared among the care team and the preventive strategies discussed and registered in the medical records	Low	Strong
We suggest Index-based EEG monitoring depth of anesthesia guidance to decrease the risk of POD	Low	Weak
We suggest multiparameter, intraoperative EEG monitoring (burst suppression, density spectral array) during anesthesia to decrease the risk of POD	Low	Weak

EEG: electroencephalogram; POD: Postoperative delirium.