Patient predictors of dexmedetomidine effectiveness for sedation in intensive care units.

Background: Dexmedetomidine, a selective α2-adrenergic receptor agonist, is increasingly used as a sedative in intensive care despite variations in patients' responses.

Objectives: To determine the effectiveness of dexmedetomidine as a sedative and specific patient characteristics that play a role in adequate sedation with dexmedetomidine.

Methods: A 6-month, pilot, prospective observational study was performed in a medical intensive care unit at an academic medical center. Patients receiving dexmedetomidine were followed up until use of the drug was stopped and they were classified as nonresponders or responders. Effective sedation was defined as a score of 3 to 4 on the Sedation Agitation Scale after the administration of dexmedetomidine. Patient characteristics, laboratory values, home and inpatient medications, and dexmedetomidine dosing information were collected to identify predictors of clinical response.

Results: During the 6-month study period, 38 patients received dexmedetomidine. The drug was ineffective as a sedative in 19 patients (50%) and effective in 11 (29%). Effectiveness could not be assessed in 8 patients because of clinical confounders. According to standard multiple logistic regression analysis, successful sedation was more likely in patients with a lower score on the Acute Physiology and Chronic Health Evaluation II (Odds Ratio [OR] 0.81; 95% CI, -0.39 to -0.03) and patients who took antidepressants at home (OR 10.27; 95% CI, 0.23 to 4.43) than in patients who had a higher score or did not take antidepressants at home.

Conclusions: Effective sedation with dexmedetomidine is variable.