Dexmedetomidine-associated bradycardia progressing to pulseless electrical activity: case report and review of the literature.

Dexmedetomidine is an alpha(2)-agonist indicated for sedation in critically ill patients and procedural sedation in nonintubated patients. It is a distinctive sedative because it does not cause respiratory depression, but it may cause hypotension and bradycardia. We describe a 74-year-old man who was receiving dexmedetomidine for agitation and experienced progressive bradycardia. The patient experienced a postoperative myocardial infarction 3 days after repair of an abdominal aortic aneurysm. A dexmedetomidine infusion was started at 0.11 microg/kg/hour, without a loading dose, for agitation; the patient's heart rate was 123 beats/minute and blood pressure was 147/70 mm Hg, both within normal limits. Over the next 6 hours, the dexmedetomidine infusion rate was increased to a maximum of 0.7 microg/kg/hour; the patient's heart rate progressively decreased to 21 beats/minute, followed by pulseless electrical activity. After 2 minutes of chest compressions and an intravenous bolus of atropine 0.4 mg, the patient regained a pulse. Dexmedetomidine was discontinued, and the patient's heart rate and blood pressure returned to within normal limits. The patient was discharged home 7 days later without any cardiac or neurologic sequelae. Clinicians need to be educated about the potential for dexmedetomidine to cause bradycardia progressing to pulseless electrical activity, and patients need to be closely monitored. Patients who receive dexmedetomidine and develop a greater than 30% decrease in heart rate may be at high risk for severe bradycardia leading to pulseless electrical activity. We urge caution when using dexmedetomidine, especially in patients with significant cardiac disease.