The epidemiology of critical illness brain dysfunction

Critically ill patients present with a range of alterations which relate to damage or dysfunction of the central nervous system. Acute brain dysfunction is arguably one of the commonest forms of organ failure in the ICU and is linked directly to adverse short-term outcome. Mounting evidence points to a range of long-term neurologic, cognitive and behavioral changes which substantially impair quality of life following critical illness. Secular trends demonstrate that mortality following severe illnesses such as sepsis and acute respiratory distress syndrome (ARDS) has declined in the past four decades, resulting in a population of long-term ICU survivors with unique characteristics. The purpose of this chapter is to outline the epidemiological features of brain dysfunction in critical illness, distinguishing between acute and post-ICU syndromes.