ST LOUIS (MD Consult) – Up to one year after an episode of critical illness, many patients have evidence of reduced cognitive function, reports a study in the October 3, 2013, issue of The New England Journal of Medicine.
The “Bringing to Light the Risk Factors and Incidence of Neuropsychological Dysfunction in ICU Survivors” (BRAIN-ICU) study included 821 adult patients receiving ICU care for respiratory failure or shock. Delirium was monitored in the hospital. At 3 and 12 months after discharge, patients were evaluated on measures of cognitive and executive function.
Rates of long-term cognitive impairment were assessed. The analysis considered the effects of delirium and use of sedative or analgesic drugs, along with adjustment for potential confounders. The lead author was Dr P.P. Pandharipande of Vanderbilt University School of Medicine, Nashville, Tenn.
Cognitive impairment was present at baseline in 6% of patients, while 74% developed delirium during hospitalization. Three-month follow-up tests suggested that 40% of patients had global cognitive function below population means—a level of impairment similar to that caused by moderate traumatic brain injury. Twenty-six percent of patients had scores comparable to that observed in patients with mild Alzheimer’s disease.
At 12 months, the same levels of impairment were present in 34% and 24% of patients, respectively. The cognitive deficits were similar for older versus younger patients. On adjusted analysis, patients with a longer duration of delirium had lower global cognitive function and lower executive function at both 3 and 12 months. Long-term cognitive outcomes were not significantly related to receipt of sedative or analgesic drugs.
Many patients who survive an episode of critical illness are left with new deficits in cognitive or executive function. There are few data on the long-term prevalence of this problem or the factors contributing to it.
Long-term cognitive outcomes are independently associated with duration of delirium, but not with the use of sedative or analgesic drugs. The authors suggest that efforts to reduce delirium in ICU patients might lessen the brain injury associated with critical illness.