Dispersion in Scores on the Richmond Agitation and Sedation Scale as a Measure of Delirium in Patients with Subdural Hematomas.

BACKGROUND: Delirium is a frequent complication of critical illness, but its diagnosis is more difficult in brain-injured patients due to language impairment and disorders of consciousness. We conducted a prospective cohort study to determine whether Richmond Agitation and Sedation Scale (RASS) scores could be used to reliably diagnose delirium in the setting of brain injury. We also examined clinical factors associated with delirium in patients with subdural hematomas (SDH) and assessed its impact on functional outcome at discharge.

METHODS: We prospectively enrolled 55 patients with the primary diagnosis of SDH admitted to the neurological intensive care unit (ICU) and screened them for delirium with the Confusion Assessment Method-ICU (CAM-ICU). As our primary outcome, we examined whether the standard deviation of RASS scores (RASS dispersion) could be used to diagnose delirium. We also looked at trends in RASS scores as a way to distinguish different causes of delirium. Then, using logistic regression, we identified factors associated with delirium in patients with SDH and quantified the impact of delirium on the modified Rankin Scale at discharge.

RESULTS: Delirium as defined by the CAM-ICU was present in 35% (N = 19) of patients. RASS dispersion correlated well with the CAM-ICU (AUC of the ROC was 0.84). Analyzing the temporal trend of changes in the RASS was helpful in identifying new brain injuries as the underlying etiology of CAM-ICU positivity. Age, APACHE II scores on admission, baseline functional impairment, midline shift on initial imaging, and infections were associated with an increased risk of delirium. Delirium was associated with a worse functional outcome.

CONCLUSIONS: RASS dispersion correlates highly with CAM-ICU positivity, and monitoring trends in RASS scores can identify delirium caused by new brain injuries. Delirium as defined by the CAM-ICU is common in patients with SDH and portends worse outcomes.