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Rapidly Reversible, Sedation-Related Delirium Versus Persistent Delirium in the Intensive Care Unit
Study Question: Does delirium that is rapidly reversed after daily sedation interruption (DSI) have the same prognosis as persistent delirium?
Study Description: This prospective, observational, investigator-blinded study evaluated consecutive medical ICU admissions at a tertiary care teaching hospital. Adult patients intubated for < 48 hours on a protocol of daily continuous sedation and analgesia interruption were eligible for inclusion. Two independent investigators performed daily bedside Confusion Assessment Method for the ICU (CAM-ICU) evaluations before and after sedation interruption to determine the impact of sedation on delirium classification.
The primary outcome was the proportion of patient days with no delirium (ND); rapidly reversible, sedation-related (RRD); persistent (PD); and mixed delirium (MD). Secondary outcomes included association of CAM-ICU assessments before and after DSI with mechanical ventilation (MV) days, ICU and hospital days, hospital discharge disposition, and 1-year mortality.
Results: A total of 102 patients with 251 evaluation days were included. Propofol (n = 97) and fentanyl (n = 101) infusions were used in almost all patients in contrast to midazolam (n = 55), and there were no significant differences in the amount of medication used per MV day among groups. Patients were 10.5 times (95% CI 5.3-21, p < 0.001) more likely to have a positive CAM-ICU before compared to after DSI. RRD was associated with fewer MV (2.5 vs. 6.2, p < 0.001), ICU (4.5 vs. 13.1, p < 0.001), and hospital days (6.7 vs. 25.4, p < 0.001) compared to PD. Each day of PD was associated with a 14% increased relative risk of mortality at 1 year (p < 0.001).
Conclusion(s): Sedation-related RRD is fundamentally different than illness-related PD and is not associated with the same poor prognosis. Coordinating sedation interruption and delirium assessments is imperative to accurately prognosticate delirium-related outcomes.
Perspective: Sedation has been identified as a risk factor for delirium, which is an important complication of ICU care. Although the patients with PD had a higher acuity of illness, this study suggests that sedation-related RRD may not result in the same outcomes as PD. Furthermore, in order to accurately classify delirium, assessments should be performed during sedation interruption. The majority of patients in this study received propofol. Further studies need to stratify by illness severity and determine the impact of dexmedetomidine and benzodiazepines on RRD.