Cognitive outcomes after critical illness

Purpose of review There is an increasing realization in the critical care community that persistent cognitive impairment is a common and disabling complication after ICU care. In this review, we discuss the best available information on the magnitude of the problem, its possible mechanisms, risk factors, management strategies and prognosis. Recent findings Estimates of the incidence of persistent cognitive impairment after critical illness vary widely across studies but the most solid prospective information indicates that it may occur in 20–40% of patients discharged from the ICU. From the available evidence, it is difficult to discriminate between de novo cognitive impairment and exacerbation of preexistent cognitive decline. The pathogenesis is multifactorial but inflammatory mechanisms causing derangements of endothelial function and blood–brain barrier integrity might play an important role. Brain atrophy and white matter tract disruption can be structural correlates of the cognitive decline. Prolonged delirium in the ICU is the strongest risk factor for the development of subsequent persistent cognitive impairment. Management strategies are currently limited to those designed to prevent and improve delirium. Cognitive trajectories may vary but a substantial proportion of patients with cognitive impairment 3 months after ICU discharge are still cognitively impaired at 12 months. Summary Persistent cognitive impairment is a major complication of critical illness. Our knowledge of this problem remains incomplete. Collaborative research is indispensable to improve our understanding of this disabling sequel and to identify ways to prevent it.