Rapidly Reversible, Sedation-related Delirium versus Persistent Delirium in the Intensive Care Unit

RATIONALE: Intensive care unit (ICU) delirium is associated with ventilator, ICU, and hospital days; discharge functional status; and mortality. Whether rapidly reversible, sedation-related delirium (delirium that abates shortly after sedative interruption) occurs with the same frequency and portends the same prognosis as persistent delirium (delirium that persists despite a short period of sedative interruption) is unknown. OBJECTIVES: To compare rapidly reversible, sedation-related delirium and persistent delirium. METHODS: This was a prospective cohort study of 102 adult, intubated medical ICU subjects in a tertiary care teaching hospital. Confusion Assessment Method for the ICU evaluation was performed before and after daily interruption of continuous sedation (DIS). Investigators were blinded to each other's assessments and as to whether evaluations were before or after DIS. The primary outcome was proportion of days with no delirium versus rapidly reversible, sedation-related delirium versus persistent delirium. Secondary outcomes were ventilator, ICU, and hospital days; discharge disposition; and 1-year mortality. MEASUREMENTS AND MAIN RESULTS: The median proportion of ICU days with delirium was 0.57 before versus 0.50 after DIS (P < 0.001). The Confusion Assessment Method for the ICU indicated patients are 10.5 times more likely to have delirium before DIS versus after (P < 0.001). Rapidly reversible, sedation-related delirium showed fewer ventilator (P < 0.001), ICU (P = 0.001), and hospital days (P < 0.001) than persistent delirium. Subjects with no delirium and rapidly reversible, sedation-related delirium were more likely to be discharged home (P < 0.001). Patients with persistent delirium had increased 1-year mortality versus those with no delirium and rapidly reversible, sedation-related delirium (P < 0.001). CONCLUSIONS: Rapidly reversible, sedation-related delirium does not signify the same poor prognosis as persistent delirium. Degree of sedation should be considered in delirium assessments. Coordinating delirium assessments with daily sedative interruption will improve such assessments' ability to prognosticate ICU delirium outcomes. Clinical trial registered with www.clinicaltrials.gov (NCT 00919698).