A growing body of literature has shown that survivors of critical illness often struggle with cognitive impairment that persists months to years after hospital discharge. We describe the epidemiology of this form of cognitive impairment—which we refer to as critical illness brain injury—and review the history and maturation of the investigation of this previously unrecognized, yet common problem. We then review the characteristics of critical illness brain injury, which can vary in severity and typically affects multiple domains of cognition. Finally, we examine known risk factors for critical illness brain injury and, based on these data, suggest approaches to patient management.


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