Postoperative cognitive dysfunction


Postoperative cognitive disorder (POCD) is a decline in cognitive function, especially in memory and executive functions.



POCD  may last from 1–12 months after surgery, or longer.



In some cases, this disorder may persist for several years after major surgery.



Postoperative neurocognitive disorders includes postoperative delirium, an acute state of confusion and inattention and postoperative cognitive dysfunction, a prolonged state of cognitive impairment that predominately affects higher level cognition skills and memory.



Postoperative neurocignitive decline mechanisms are speculative, but include neuroInflammation as a result of perioperative stress, vascular disorders or acceleration of the neurocognitive decline in patients with previously undiagnosed neuro degenerative disorder, such as pre-clinical dementia.



The causes of POCD are not understood. 



It does not appear to be caused by lack of oxygen or impaired blood flow to the brain



POCD  is equally likely to occur under regional and general anesthesia.



POCD may be mediated by an inflammatory response to surgery.



In a study of patients who underwent non-cardiac surgery covert stroke occurred in 7% of elderly patients and was associated with an increased risk of postoperative delirium and long-term cognitive defects.



Age, duration of anaesthesia, introperative complications, and postoperative infections were found to be associated with POCD.



Patient’s aged 65 years and older are estimated to experience delirium 65% of the time, and 10% of patients develop long-term cognitive decline after non-cardiac surgery.



Post operative delirium is associated with prolonged hospitalization, more days with mechanical ventilation, and functional decline.



Patient discharged from the hospital who had experienced postoperative delirium are at increased risk for worsening functional and psychological health, progressive cognitive decline, dementia and death.



Fewer patients experience POCD with total intravenous anaesthesia (TIVA) compared to inhalational anaesthesia. 



Examining adults 55 and older who have major non-cardiac surgeries: finding that upward of 30 percent of patient’s cognitive testing was significantly worse than their baseline 3 months later.



POCD is common after cardiac surgery.



POCD also exists after major non-cardiac surgery, although at a lower incidence. 


The risk of POCD increases with age.

Strategies to reduce postoperative neurocognitive this function include adopting preoperative healthy lifestyles with recommendations on physical activity, tobacco cessation, nutrition, and hypertensive and diabetic management.

Preoperative protocols providing orientation, cognitive stimulation and mobilization improved memory, speed, attention, flexibility, problem-solving, and decreased delirium incidence.

Perioperative risk factors for postoperative neurocognitive disorders include: 

Depression, hypertension, sleep disorders, glycemia, alcohol or other substance abuse, medication, impaired nutritional status, poor perioperative pain management, family and social support system failures.



The type of surgery is important as there is a very low incidence of POCD associated with minor surgery.



WHILE POCD is common in adult patients of all ages at hospital discharge after major noncardiac surgery,


only the elderly are at significant risk for long-term cognitive problems. 



Patients with POCD are at an increased risk of death in the first year after surgery.



There appears to be no causal relationship between cerebral hypoxia and low blood pressure and POCD. 



It I’d just as likely to occur after operations under regional anesthesia as under general anesthesia, but more likely after major operations than minor operations.



More likely to occur after heart operations than other types of surgery.



More likely in older patients with high alcohol intake,and those with higher preoperative ASA physical status scores.



It occurs more likely in people with lower educational level than those with a higher educational level.



People with prior history of a stroke


are more likely to develop POCD.



It is more likely to develop in elderly with pre-existing declining mental functions, termed mild cognitive impairment (MCI).



Delirium and severe worsening of mental function is very likely in those with clinically evident Alzheimer’s disease or other forms of dementia, as well as those with a history of delirium after previous operations.


Postoperative neurocognitive disorders develop between an interaction of baseline vulnerabilities and other risk factors.


Non-modifiable risk factors for PND (postoperative neurocognitive disorders include: age, compromised level of cognitive skills, procedure related invasiveness, duration, and urgency, and postoperative admission to an ICU.


No compelling medical, pharmacologic, or intraoperative intervention care pathways are known to limit the incidence and severity of PND.


Among patients older than 65 years, avoiding benzodiazepines,  entrally acting cholinergics, meperidine, phenothiazines, and antipsychotic agents during The preoperative period decreases the risk of cognitive change.




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