Coma, Delirium, and Cognitive Dysfunction in Critical Illness

Syndromes of global cerebral dysfunction associated with critical illness include acute disorders such as coma and delirium, and chronic processes namely cognitive impairment. These syndromes can result from direct cerebral injury, but in many instances develop as a complication of a systemic insult such as cardiac arrest, hypoxemia, sepsis, metabolic derangements, and pharmacological exposures. Coma frequently evolves into phenomenologically distinct disorders of consciousness such as the vegetative state and the minimally conscious state, and it must be differentiated from conditions in which consciousness is preserved, as in the locked-in state. Coma and delirium are independently associated with increased short-term mortality, while cognitive impairment has been linked to the poor long term functional status and quality of life observed in critical illness survivors. Advances have been made in defining, scoring, and delineating the epidemiology of cerebral dysfunction in the intensive care unit, but research is needed to elucidate underlying mechanisms, with the goal of identifying targets for prevention and therapy.