Coma, Delirium, and Cognitive Dysfunction in Critical Illness

Recent research highlights a spectrum of cerebral dysfunction acquired in critical illness, which may take the form of coma, other states of impaired consciousness, delirium, or cognitive impairment. These disorders are common and may be associated with a deterioration in the physical and mental well-being of survivors of the ICU. Although advances have been made in recognizing brain dysfunction in critical illness and in delineating its impact, fundamental questions persist regarding its etiology, pathogenesis, and natural history. These questions need to be addressed with a combination of basic science, translational and clinical approaches. Large-scale cohort studies are necessary to provide insight into the complex relationships between post-ICU cognitive impairment, events occurring in the ICU, and premorbid function. The neural substrates of delirium should be explored using available functional and metabolic brain imaging protocols. There is a need to elucidate brain injury mechanisms that are related to systemic insults, such as hypoxemia, shock, inflammation, and sepsis. The postulated toxic effects of commonly administered drugs (eg, sedatives and analgesics) should be investigated using experimental and epidemiologic paradigms. Results from these studies will provide a mechanistic framework for designing effective prevention and treatment strategies to decrease the long-term burden of critical illness.