Chapter 17. Coma and Delirium

John F McConville, MD
DOI: 10.1378/critcare.21.17
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  • Distinguish coma and delirium from other neurologic conditions.

  • Identify predictors of outcome for patients in a coma.

  • Be able to assess delirium at the bedside.

  • Identify treatment strategies for delirium.


Cerebral dysfunction is very common in the ICU. CNS dysfunction can result from primary (acute stroke) or secondary (severe sepsis) insults. Coma is a transitional state wherein patients are unable to respond to their environment. Coma occurs in up to 15% of mechanically ventilated patients, 80% of patients with cardiac arrest, and approximately 16% of patients with sepsis. Drug overdose is the most common toxic-metabolic cause and trauma and hypoxic-ischemic encephalopathy are the most frequent primary cerebral events resulting in coma. A quick neurologic exam that assesses level of consciousness and brainstem reflexes, motor exam, and respiratory exam should be completed as soon as possible. A physical exam remains the best determinant that clinicians use to prognosticate for patients with cerebral dysfunction. Five neurologic signs predict death or poor neurologic outcome in survivors of cardiac arrest: absent corneal reflexes or pupillary response at 24 h, absent withdrawal response to pain at 24 h, and no motor response at 24 h or 72 h. In addition to coma, delirium is another common cause of cerebral dysfunction in the ICU. Delirium is defined as a fluctuating acute confused state that includes impaired attention and disorganized thinking. Inattention, which is measured using the Confusion Assessment Method for ICU, is required to diagnose delirium. Several studies have conclusively demonstrated that ICU delirium increases 6-month mortality. Small studies support medication and nonpharmacologic interventions in the treatment of delirium.


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