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ICU Pain, Anxiety, Agitation, Delirium: In Search of the Holy Grail


Kamlesh Thaker

From Methodist DeBakey Heart Center, Houston, Texas, US
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Pain, anxiety, agitation, and delirium occur in 15-60% of elderly hospitalized patients. The prevalence of anxiety and delirium in the mechanically ventilated ICU patients ranges from 7-80%, with the highest rates seen in those aged 65 years or older.1-4 Despite the availability of a few quickly administered bedside tests, the multifactorial causes of anxiety and delirium, many of which are preventable, are underrecognized by many caregivers (Table 1). Anxiety and delirium are associated with significant hospital morbidity and post-discharge morbidity and mortality (Figure 1). Definitions of key terms for the purposes of this article include the following:

  • Agitation - an excessive motor activity associated with internal tension. This motor activity is usually nonpurposeful but may be irrationally purposeful and counterproductive.
  • Anxiety - a sustained state of apprehension with accompanying autonomic arousal in response to a real or perceived threat.
  • Delirium - an acute, potentially reversible impairment of consciousness and cognitive function that fluctuates in severity. Manifestations include apprehension, agitation, cognitive distortion, abnormal thought processes, hallucinations, and impairment of short-term memory, arousal and attention.
  • Psychosis - active hallucination; however, in the literature, there are misnomers such as ICU psychosis, toxic confusional state, critical illness encephalopathy, and septic encephalopathy.
  • Subsyndromal delirium - the presence of some, but not all, of the criteria for delirium.
  • Stupor - a sustained state of spontaneous unarousability interruptible only by vigorous, direct external stimulation.
  • Coma - a state of unarousability and unresponsiveness to all stimuli.

Given the range of manifestations, the continuum/spectrum of acute brain dysfunction is shown in Figure 2.

To assess the presence of delirium, one may use various bedside tools, such as the Confusion Assessment Method (CAM-ICU), which Ely et al.7 modified from the Diagnostic and Statistical Manual of Mental Disorders (DSM-IIIR).8 This is shown in Figure 3.

How to Cite: 1. Thaker K. ICU Pain, Anxiety, Agitation, Delirium: In Search of the Holy Grail. Methodist DeBakey Cardiovascular Journal. 2007;3(1):13-17. DOI:
Published on 01 Jan 2007.
Peer Reviewed


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