Chronic neurocognitive effects of critical illness

Until relatively recently critical care practitioners have focused on survival of their patients and not long-term outcomes. An increasing body of research has examined patient outcomes beyond discharge from the intensive care unit and hospital. One area of focus is neurobehavioral outcomes including neurocognitive sequelae and neuropsychiatric disorders such as depression and anxiety. Cognitive functions are brain-based or mental activities that involve acquiring, storing, retrieving, and using information and include domains such as memory, attention, executive function, mental processing speed, spatial abilities, and general intelligence. It is known from other medical specialties that impaired cognitive function can have a broad, substantial, and long-lasting impact on a patient's life. This paper examines the current evidence for neurocognitive impairments in survivors of critical illness.

Recent studies support the hypothesis that critical illness can lead to significant impairments in neurocognitive function. Current work indicates that the neurocognitive impairments can last for months or years after a patient arrives home and may have important consequences for quality of individual and family life and for ability to return to work as well as substantial economic costs. The mechanisms of neurocognitive impairments are not fully understood, but in acute respiratory distress syndrome hypoxemic burden appears important.

Among the potential consequences of critical illness are now included neurocognitive impairments. Future research should include the search for strategies for the early identification of neurocognitive impairments, mechanisms of brain injury, and therapeutic modalities designed to prevent or decrease neurocognitive morbidity.