Dementia, Post-Operative Delerium,
Post-Operative Cognitive Dysfunction (POCD)

Updated May 25, 2014
Author: A. Miller

Description: Factors which influence the development of POCD, with recommendations for prevention and management. From a CME lecture by Anthony Miller MD 2014

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Introduction & Definitions (3)

  1. Dementia: Loss of function in one or more cognitive domains:
    1. Attention, memory, executive function, language, perception, social
    2. Loss of independence
    3. Not a single disease, but a non-specific syndrome (i.e., set of signs and symptoms).
    4. DSM-5 renamed the dementias as neurocognitive disorders, with various degrees of severity.
      1. from neural degeneration diseases: Alzheimer's, Parkinson's, Huntington's
      2. neural toxicity: alcohol, drugs
      3. from hypoxia/ischemia (stroke, vasculitis)
      4. Nutritional deficiencies: Vit. B12, folate deficiencies
      5. Infection: AIDS dementia complex, Creutzfeldt-Jakob disease
      6. Head injury -- either a single severe head injury or chronic traumatic encephalopathy
      7. Certain types of hydrocephalus, as a result of developmental abnormalities, infections, injury, or brain tumors
    5. Presentation of Dementia
      1. Fixed cognitive impairment
      2. Slowly progressive
      3. Rapidly progressive

  2. Delerium: a change in mental status, characterized by a prominent disturbance of attention and reduced clarity of awareness of the environment.
    1. Onset acute , develops within hours to days, and tends to fluctuate during the course of the day.
    2. Inability to focus, sustain, and shift attention is accompanied by other cognitive symptoms (e.g., disorientation, episodic memory dysfunction) and/or perceptual disturbances (misinterpretations, illusions, or hallucinations)
    3. Symptoms are numerous, vary from patient to patient, vary within patients over time, and are shared by a variety of other disorders, such as dementia, anxiety, depression, and psychosis, all of which contribute to difficulties in diagnosis.
    4. Subtypes of Delerium (3):
      1. Hyperactive (25%) form of delirium, tends to be clinically obvious.
      2. Hypoactive (75%) form often unrecognized, misdiagnosed, mistaken for depression or dementia, or attributed to old age,
        • Patients may seem quiet and subdued in their disorientation.
        • Relationship between delirium and dementia is complex, and the syndromes may overlap
      3. Mixed
    5. Classification by Etiology: (4)
      1. Due to a general medical condition,
      2. Substance-induced delirium (medication or toxin),
      3. Substance withdrawal delirium
      4. Delirium due to multiple etiologies, or NOS
    6. Post-Operative Delerium: (2)
      1. Emergence Delerium:
        • Seen during or immediately after emergence from GA
        • Usually resolves within minutes to hours.
        • Occurs in all age groups, with some predominance in children.
        • Directly correlated with the administration of GA
        • Mimics stage II (excitation) of ether anesthesia as described by Guedel, and
        • Usually resolves without sequelae.
        • Fits the diagnostic criteria for a substance-induced delirium.
      2. Post-Operative or Interval Delerium
        • After a lucid interval
        • Between postoperative days 1 and 3
        • generally resolves within hours to days, although symptoms may persist for weeks to months
        • More likely to result in complete recovery than other forms of delirium.
        • Intensive Care Unit (ICU) delirium occurs in the ICU, primarily in those patients requiring mechanical ventilation; previously referred to as ICU psychosis.
        • ICU delirium makes no distinction between medical and surgical patients, so many cases of ICU delirium could also be classified as postoperative delirium.
    7. Population at Risk for Post-Operative Delerium
      1. Older adults after general anesthesia: Incidence : 5–15%
      2. surgery for hip fracture is higher, ranging from 16% to 62%, average rate of 35%. Delirium is the most common complication after hip fracture, but this patient population also has a high incidence of delirium before surgery.
      3. Predisposing Risk Factors for PostOp Delerium include:
        • Vision impairment
        • Severe illness
        • Cognitive impairment
        • BUN:creatinine ratio > 18
        • Use of physical restraints
        • Malnutrition
        • Use of a urinary bladder catheter
        • Fluid / electrolyte abnormalities
        • Infection
        • Preoperative depression
        • Intraoperative blood loss, postop transfusions, postop Hct < 30%
        • severe postoperative pain
        • Drugs
          • sedative–hypnotics
          • narcotics
          • anticholinergics
          • benzodiazepines: controversial. Lorazepam has been specifically associated with delirium in the ICU.
          • Isoflurane
        • GA vs Regional: No significant. difference (!)

  3. Post-Operative Cognitive Dysfunction: POCD: deterioration of cognition that is temporally associated with surgery and anesthesia
    1. difficult to assess objectively
      1. evaluating the severity of, and characterizing POCD depends on assessments of both preoperative (baseline) and postoperative cognitive function
      2. Subjective self-reported cognitive symptoms do not substitute for objective cognitive testing,
    2. More than just normal aging
    3. Not dementia; generally does not interfere with independence
    4. May not be appreciated for weeks to months post-op.
    5. Mild Cognitive Impairment:
      1. a transitional zone in the spectrum of cognitive function from normal aging to progressive dementing conditions, such as Alzheimer and cerebrovascular diseases.
      2. There is no information available concerning the impact of surgery and anesthesia on this subset of patients that may be at greatest risk for POCD.
      3. There is no evidence that anesthesia and surgery increase the incidence of Alzheimer disease.
  4. Post-Op Delerium, POCD, and Dementia
    1. Postoperative delerium may be a harbinger of POCD or an emerging dementia
    2. In ICU patients, delerium seems to be a prodrome for need of long term cognitive therapy
continiuum

PreOperative Risk Factors for POCD

  1. Age ≥ 70 (≥ 65?) years
  2. Prior history of delirium or cognitive impairment
  3. Reduced function, Impairment of Activities of Daily Living (ADL)
    1. walking, bathing,dressing,toileting, brushing teeth, eating
  4. Impaiment of Instrumental Activities of Daily Living (IADL)
    1. cooking, driving, telephone, computer, keeping track of finances, managing medications
  5. Frailty: wt loss, exhaustion, grip, walking, activity
  6. History of alcohol abuse
  7. Depression
  8. Prior stroke or TIA
  9. Type of surgery: Hip fx, Cardiac, AAA, Thoracic
  10. Abnormal Na+, K+, glucose, or hypoalbuminemia

Prevention & Management of POCD

  1. Avoid sensory impairment, misinterpretation
    1. Glasses, hearing aids
    2. Cognitive stimulation
  2. Nonpharmacologic promotion of sleep (milk, music, lights)
  3. Mobilization
  4. Avoid psychoactive medications
  5. Eliminate unnecessary meds
  6. Fluids and nutrition
  7. Avoid/treat complications
    1. Bowel, infection (UTI), DVT, O2, electrolytes, glucose, hct, etc
  8. Treat pain:
    1. Opioids may precipitate delirium, but so does undertreated pain
    2. limit <10 mg MSO4/day after hip fx delirium
    3. Give opioids on a schedule vs. prn
    4. Be wary of PCA, esp. with cognitive impairment
    5. Use non-opioid methods: Acetaminophen, NSAIDs
    6. Regional analgesia (but watch epidural opioids)
    7. Pharmacologic Prevention?
      1. In a word . . . No! Not successful:
      2. Cholinergics: ACEI rivastigmine (used for Parkinson's dementia) increased mortality
      3. Haloperidol for agitation:
        • adult dose of 0.5–1 mg IV every 10–15 min until agitated behavior is controlled.
        • IM dosing less desirable but can be employed using 2–10 mg, waiting 60–90 min between doses.
        • Extended half-life in the elderly (up to 72 h) and deep sedation can last for several days.
        • Useful in immediate management of agitation but does not alter duration of delirium.
      4. Other antipsychotics: ziprasidone and olanzapine, not tested in patients with medical or surgical comorbidities
    8. Early (preop or within 24 hours postop) geriatrics consultation
    9. Sedation
      1. Propofol: superior to benzodiazepines
      2. Dexmedetomidine: Superior to benzos and maybe to propofol also (intubated patients)
      3. The level of sedation might also be a factor

PreOp Evaluation for Patients at Risk of Dementia/ POCD

  1. H & P: Identify Preoperative Risk Factors:
    1. Age ≥ 70 (≥ 65?) years
    2. Prior history of delirium or cognitive impairment
    3. Reduced function, Impairment of Activities of Daily Living (ADL)
      1. walking, bathing,dressing,toileting, brushing teeth, eating
    4. Impaiment of Instrumental Activities of Daily Living (IADL)
      1. cooking, driving, telephone, computer, keeping track of finances, managing medications
    5. Frailty: wt loss, exhaustion, grip, walking, activity
    6. hx of alcohol abuse
    7. hx of Depression
    8. Prior stroke or TIA
    9. Type of surgery: Hip fx, Cardiac, AAA, Thoracic
    10. Abnormal Na+, K+, glucose, or hypoalbuminemia
  2. Basic laboratory testing: CBC, BMP, UA
    1. elevated creatine suggests slow drug clearance
  3. Review medications!!
  4. CT scan only if a new focal neurological deficit

Anesthetic Plan / Intraoperative Management

Recommendations to help Minimize P.O. Delerium and POCD

  1. Preop Discussion: Patients and family are asking about it
    1. Delirium: What to Say:
      1. a Real phenomenon
      2. Still learning about true cause
      3. Probaly related to patient risk factors, procedure, & anesthesia/sedation
    2. POCD: What to Say:
      1. a Real phenomenon
      2. True incidence is unknown
      3. Cause is unknown
      4. Might be related to patient risk factors
      5. Will do my best to avoid things likely to make it worse
  2. Anesthetic Plan / Intraoperative Management
    1. Same strategy would work for delirium & POCD Depth of Anesthesia/Sedation
    2. Medications to AVOID:
      1. Definitely AVOID:
        • Benzodiazepines
        • Meperidine
        • Anticholinergics, such as
          • Promethazine
          • Diphenhydramine
          • Atropine
          • Scopolamine
      2. Probably AVOID:
        • Isoflurane
      3. Previously avoided, but probably OK
        • N2O – no effect in one human study
        • Ketamine – reduces delirium after cardiac surgery
    3. Consider spinal anesthesia, especially for hip fracture
    4. Sedation with propofol or dexmedetomidine
      1. Avoid deep sedation
      2. Analgesia
      3. Non-opioid
      4. Regional
      5. Be careful with epidural opioids
    5. Attention to detail
      1. Oxygenation
      2. VS, incl temperature
      3. Hydration
      4. Hgb
      5. Electrolytes (esp. Na+)
      6. Antibiotics
  3. Post-Op: Treat Delirium Early
    1. Look for reversible causes, especially medications
    2. Haloperidol for agitation, unless contraindicated
      • 0.5-1 mg IV q 15 min to 1 hr until agitation controlled
      • No benefit to more than 2-3 mg
      • Reduces severity, but does not alter duration of delirium
      • Be aware of QT prolongation
      • Not for patients with Parkinson’s, Lewy Body Dementia, NMS
    3. Avoid benzodiazepines, unless alcohol or benzo withdrawal or haloperidol contraindicated
    4. Avoid meperidine
    5. Eliminate use of any anticholingergics
    6. Avoid physical restraint, if possible Including “informal”
    7. Possible role for dexmedetomidine?
    8. Early Geriatrics or hospitalist consultation

References