Perioperative neurocognitive dysfunction and role of dexmedetomidine in radical colon cancer surgery in elderly patients

Table 1 The general and specific risk factors for perioperative neurocognitive disorders and the preventive measures to be taken to mitigate the incidence and severity of postoperative cognitive dysfunction

Specific factors	Risk factors	Preventive measures for neuroprotection
Patient-related	Frailty	(1) Multidisciplinary approach; (2) Identification of high-risk patients; (3) Optimization of comorbidities; (4) Establishing baseline cognitive function/dysfunction; (5) Neuropsychiatric/pharmacist consult for alcohol/psychotropic dependence; (6) Consideration of informed consent with patient and family; and (7) Cognition preconditioning
	Age > 65 years
	Dementia, neurodegenerative disorder
	Excessive alcohol consumption
	Polypharmacy including psychotropic drugs
	Vascular disorders
	Sleep disorders
	Diabetes mellitus
	Prior neuron damage like stroke or traumatic brain injury
Surgery-related	Type of surgeries: (1) Open cardiac surgery; (2) Invasive cardiac surgery; (3) Major Orthopedic surgery; (4) Head and neck surgery; and (5) Colorectal surgeries	Measures to decrease the duration of surgery
	Increased duration of surgery is associated with increased risk of POCD	Identifying the type and expected duration of surgery
	Postoperative medical and surgical complications	Minimization and early treatment of any postoperative complications
Anesthesia-related	General factors: (1) Excessive depth of anesthesia under GA; (2) Excessive sedation in regional anesthesia; (3) Extremes of blood pressures; (4) Hemodynamic fluctuations; and (5) Cerebral desaturation	(1) Depth of anesthesia monitoring using BIS, entropy; (2) Minimizing excessive sedation; (3) Hemodynamic monitoring and preventing extreme fluctuations from baseline; (4) Cerebral oximetry monitoring in high-risk cases; and (5) Opioid minimizing/sparing techniques
	Specific agents: Benzodiazepines, gabapentinoids, ketamine, opioids, diphenhydramine, metoclopramide, anticholinergics (particularly scopolamine), and diphenhydramine

BIS: Bispectral index; GA: General anesthesia; POCD: Postoperative cognitive dysfunction.