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Causes and epidemiology of agitation, confusion, and delirium in the ICU 

Causes and epidemiology of agitation, confusion, and delirium in the ICU
Causes and epidemiology of agitation, confusion, and delirium in the ICU

Eduard E. Vasilevskis

and E. Wesley Ely

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date: 27 January 2022

Confusion is a non-specific, non-diagnostic term to describe a patient with disorientation, impaired memory, or abnormal thought process. Agitation describes an increased level of psychomotor activity, and anxious or aggressive behaviour. Many agitated patients may also be delirious, yet they only represent a minority of all delirious patients. ICU delirium is an acute cognitive disorder of both consciousness and content of thought. The hallmark of ICU delirium is a fluctuating mental status, inattention, and an altered level of consciousness. Delirium is the end product of a sequence of insults and injury that lead to a common measurable manifestation of end-organ brain injury. It does not have a single aetiology, but often has multiple different and potentially interacting aetiologies. Both non-modifiable and modifiable risk factors play important roles in the development of delirium. Importantly, the new onset of delirium should prompt the physician to investigate the underlying cause. Cognitive impairment and age are among the most important non-modifiable risk factors, whereas administration of benzodiazepines is the greatest. The alpha-2 adrenoceptor agonist dexmedetomidine shows promise as a sedative reducing the risk for delirium when compared with benzodiazepines.

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