Understanding the neurohumoral causes of anxiety in the ICU. Clinical consequences include agitation, brain failure, delirium.

Severe anxiety can disrupt neurohumoral metabolism and lead to agitation and brain failure, which may result in delirium. Predisposing factors include cerebral vascular or endocrine insufficiency, cardiopulmonary decompensation, poor tissue perfusion, multiple medications, and sleep-wake cycle disruption; the stressful ICU environment puts patients especially at risk. Stress-induced noradrenergic hyperactivity can precipitate panic attacks; dopaminergic hyperactivity can lead to delirium (marked by paranoid delusions, visual or auditory hallucinations, and psychomotor agitation). The underlying cause of anxiety must be identified to guide appropriate therapy.