Patient Care

Long-Term Cognitive Impairment after Critical Illness


Clinical question: Are a longer duration of delirium and higher doses of sedatives associated with cognitive impairment in the hospital?

Background: Survivors of critical illness are at risk for prolonged cognitive dysfunction. Delirium (and factors associated with delirium, namely sedative and analgesic medications) has been implicated in cognitive dysfunction.

Study design: Prospective cohort study.

Setting: Multi-center, academic, and acute care hospitals.

Synopsis: The study examined 821 adults admitted to the ICU with respiratory failure, cardiogenic shock, or septic shock. Patients excluded were those with pre-existing cognitive impairment, those with psychotic disorders, and those for whom follow-up would not be possible. Two risk factors measured were duration of delirium and use of sedative/analgesics. Delirium was assessed at three and 12 months using the CAM-ICU algorithm in the ICU by trained psychology professionals who were unaware of the patients’ in-hospital course.

At three months, 40% of patients had global cognition scores that were 1.5 standard deviations (SD) below population mean (similar to traumatic brain injury), and 26% had scores two SD below population mean (similar to mild Alzheimer’s). At 12 months, 34% had scores similar to traumatic brain injury patients, and 24% had scores similar to mild Alzheimer’s. A longer duration of delirium was associated with worse global cognition at three and 12 months. Use of sedatives/analgesics was not associated with cognitive impairment.

Bottom line: Critically ill patients in the ICU who experience a longer duration of delirium are at risk of long-term cognitive impairments lasting 12 months.

Citation: Pandharipande PP, Girard TD, Jackson JC, et al. Long-term cognitive impairment after critical illness. N Engl J Med. 2013;369(14):1306-1316.

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