Abstract 18979: Calm Before the Storm: Exploring the Risk of Torsades De Pointes With Dexmedetomidine Administration

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Introduction: Corrected QT interval (QTc) prolongation is the known side effect of multiple medications especially in antipsychotic and antiarrhythmic family. Patients with either inherited or secondary prolonged QTc should be monitored closely as they can develop life threatening complications like Torsades de-pointes and ventricular fibrillation. Here we present a case of cardiac arrest secondary to dexmedetomidine. Case: A 49-year-old female with history of bipolar disorder was admitted to intensive unit for seizure after intentional ingestion of uncounted amount of diphenhydramine pills. Patient was intubated for airway protection and started on propofol. Her vitals at the time of admission included the pulse rate of 76, blood pressure of 102/49 mmHg. Her urine drug screen was positive for TCA and cannabinoids. Her ECG at the time of admission was significant for prolonged QTC of 600msec that improved to 460msec in the consecutive ECGs after administration of total of 4mg intravenous magnesium. Continuous EEG was negative for seizure and she was weaned off sedation. After awakening, she became agitated, after pushes of benzodiazepines, was eventually started on dexmedetomidine. Twenty minutes after starting low dose dexmedetomidine, patient was noted to be in cardiac arrest. Reviewing telemetry prior to event, revealed the R on T phenomenon and Torsades de pointes that lasted for few seconds with progression into ventricular fibrillation. Discussion: Currently dexmedetomidine is labeled with a low to possible risk of Torsade de pointes and QTC prolongation. Dexmedetomidine induced Torsade de pointes might be explained by bradycardia in patients which causes further prolongation of QT interval. Studies have shown that continuous IV infusion of dexmedetomidine at rate of 0.3 mcg/kg/hour can worsen QTC prolongation. Conclusions: In this case we present a case of VFib arrest secondary to Torsade after twenty minutes of infusion of dexmedetomidine without any sign of bradycardia prior to the event. This carries a significant importance as it shows this drug carries a potential risk of QTc prolongation similar to previous studies. Whether this side effect is dose dependent or not requires further investigation.

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