Postoperative Cognitive Impairment (POCD)

Cognitive disorders are common during the postoperative period, among them postoperative delirium and postoperative cognitive impairment has the highest incidence.

Postoperative delirium is an acute, fluctuating disturbance of consciousness characterized by disorientation, impaired focus, attention. perception and behavior following a surgery.
POD takes a longer time to develop than POCD and it is progressive and irreversible.

Postoperative cognitive impairment is the deterioration of a patient’s memory and learning performance following a surgery.
POCD can occur even before being discharged from the hospital.

In this article, my main focus is to discuss about postoperative cognitive impairment (POCD)

Incidence

  • 35 – 45% of general surgical population is affected
  • 33.34% of patients who underwent surgery will develop POCD at discharge
  • 10% of patients who underwent surgery will develop POCD at 3 months after surgery

Pathophysiology

Unfortunately, the pathogenesis is not clearly understood.

POCD is thought to occur due to the disturbances in the neuro-chemical environment of the brain during surgery. There can be various factors that can lead to a disturbance in the neuro-chemical environment of the brain.

  • Hyperventilation
  • Hypotension
  • Cerebral microemboli (Particularly in patients who undergo cardiopulmonary bypass surgery
  • Inflammatory response to surgery

These factors are well identified through research to cause cognitive impairment following surgery.

Risk Factors

  • Surgery
    • Major surgeries increases the risk
    • Multiple surgery / Reoperation
  • Postoperative infection
  • Anaesthesia
    • General anaesthesia >> Regional anaesthesia
    • Prolonged anaesthesia
    • Hypotension, hyperventilation, hypoxia during surgery
    • Poor pain management
  • Patient factors
    • Elderly (> 60 years)
    • Pre-existing medical conditions (Cardiac, renal, vascular)
  • Emboli

Clinical Presentation

Patients can be affected in varying degrees, some can have a mild disease whilst some can present with severe form of POCD.

POCD can occur even before being discharged from the hospital. Cognitive impairment in POCD has a fluctuating pattern. These changes are subtle in most cases, but in few patients these changes can be noticed, first detected by the family members and close friends and later stages patient also become aware of these impairments.
Common presentations of POCD are listed below.

  • Impaired memory and inability to recall previous events
  • Decline in the previous learning ability
  • Reduced performance
    • Unable to complete tasks which were done easily before
    • Decline in reading ability
    • Multitasking becomes difficult
  • Troublesome fine movements
    • Inserting thread into the needle
  • Language and comprehension problems
    • Forgetfulness of words
    • Problems following conversations

Diagnosis

A series of neuropsychological tests are performed. This test include several components to test the functional ability in memory, learning, attention, language and motor function.

After establishing baseline values, these tests are again performed following surgery to assess the decline of the patients’ performance.

Treatment

Treatment is mainly focused on two elements.

  • Exclusion of organic psychosyndrome
  • Symptomatic management of POCD symptoms

No treatment is currently available for POCD.
Most patients return to baseline within few months following surgery.
Compliance to postoperative advice & medication and good family support aids faster recovery.

* Reseachers have found that the use of benzodiazepines preoperatively, reduces long term postoperative cognitive dysfunction.

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