Postoperative Delirium:

1
Postoperative Delirium
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Postoperative Delirium

• Frequently encountered complication
• 37 incidence ranging from 0-73 (Winawer)
• Often unrecognized or misdiagnosed
• Failure to prevent and identify has significant
  implications on morbidity and mortality
• First sign of catastrophic event, e.g. MI, sepsis
• Delayed functional recovery
• Increased length of stay
• Higher postoperative complication rates

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Definition

• DSM-IV (Diagnostic and statistical manual of
  mental disorders) hallmark features
• Disturbance of consciousness with reduced ability
  to focus, sustain, or shift attention
• A change in cognition or the development of a
  perceptual disturbance that is not accounted for
  better by a pre-existing, established, or
  evolving dementia.
• Disturbance develops during a short period and
  tends to fluctuate during the course of the day
• Varies based on cause

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Preoperative Risk Factors

• Age
• Pathologic states in the brain
• Psychiatric illness
• Drugs used in the perioperative period
• Intoxication/withdrawal
• Endocrine/metabolic
• Hyponatremia
• Hypoglycemia

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Operative Risk Factors

• Type of surgery
• Orthopedic
• Ophthalmic
• Cardiac
• Anesthetic drugs used

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Causative Agents

• More than 500 drugs may induce the syndrome
  (Schultz)
• Antihistamines
• Phenothiazines- promethazine
• Antiparkinsonian drugs- benztropine
• Belladonna alkaloids- atropine, scopolamine
• Tricyclic antidepressants
• Ophthalmic cycloplegics- tropicamide

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Clinical Features

• Central
• Incoherent speech
• Dementia/delirium
• Excitation and agitation- violent behavior
• Stupor, somnolence or coma
• Hallucinations
• Central respiratory failure
• Memory or thought disturbances
• Ataxia
• Flaccid paralysis
• Convulsions/seizures
• Peripheral
• Urinary retention
• Decreased intestinal motility and constipation
• Decreased to absent sweating with hot and dry
  skin
• Fever with potential for severe hyperthermia
• Mydriasis- dilation of pupils
• Cycloplegia- inability to accommodate causing
  blurred vision
• Peripheral vasodilatation

8
Postoperative Risk Factors

• Hypoxia
• Pain
• Sepsis
• Myocardial infarction
• Electrolyte or metabolic disturbance
• Sensory deprivation or overload e.g. ICU setting

9
Pathogenesis

• Poorly understood
• Structural brain disorders (subcortical
  structures) increase risk, however most patients
  have no identifiable abnormalities
• Cholinergic pathways play a significant role
• As oxidative metabolism of the brain decreases
  neurotransmitters including Ach decline
• Decreased production can precipitate delirium
• Medications with anticholinergic properties can
  cause confusion/delirium

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Management

• Prevention
• Identification of the underlying disorder
• Treatment

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Prevention

• Identifying and addressing underlying medical
  problems
• Avoiding precipitant medications
• Optimizing fluid status
• Aggressive treatment of pain
• Ensuring tranquil postoperative care setting

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Pharmacologic treatment

• Physostigmine
• Alleviation of symptoms after its administration
  confirms diagnosis of anticholinergic syndrome
• It is the specific antidote for anticholinergic
  poisoning
• Haldol
• Effective in controlling agitation and psychotic
  behavior
• Benzodiazepines
• Drugs of choice in alcohol and sedative
  withdrawal syndromes

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Physostigmine

• Acetylcholinesterase inhibitor
• Tertiary amine, crosses the blood brain barrier
• The dose is 10-40 mcg/kg (1-2 mg over 2-5 minutes
  for adults or 0.5 mg in children, which may be
  repeated in 40 minutes)
• Rapid onset with a 30-60 minute duration

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Adverse effects

• Anticholinergic properties
• Muscarinic
• Bradycardia
• Profuse perspiration
• Salivation
• Nausea/vomiting
• Hyperperistalsis- loss of bladder and rectal
  control
• Miosis/difficulty focusing
• Bronchoconstriction
• Abdominal cramping
• Nicotinic
• Skeletal muscle weakness/paralysis with resultant
  apnea
• Central Nervous system
• Confusion
• Ataxia
• Seizures
• Coma
• Depression of ventilation

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Summary

• Delirium
• Common
• Associated morbidity and mortality
• Often overlooked or misdiagnosed
• Cause multifactorial
• Pathogenesis incompletely understood
• Diagnosis is not algorithmic

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References

• Feeley, Thomas W Assesment and Management of
  Patients in the Postanesthesia Care Unit. ASA
  1990 159-160.
• Parikh SS, Chung F. Postoperative Delirium in
  the Elderly. Anesth Analg 1995 80 1223-32.
• Schultz U, Idelberger R, Rossaint R, Buhre W.
  Central anticholinergic syndrome in a child
  undergoing circumcision. Acta Anaesthesiol
  Scand 2002 46 224-226.
• Stoelting RK. Pharmacology and Physiology in
  Anesthetic Practice. 1987 226-228.
• Svirbely, JR. The Medical Algorithms Project.
  2002 32.27 1-3.
• Szajewski, J. Acute Anticholinergic Syndrome.
  IPCS INTOX 1995 1- 3.
• Winawer, Neil. Postoperative Delirium. Medical
  Clinics of North America 2001 85 1229-1239.