Insulin Treatment of Shock Induced by Acute Propafenone Toxicity Refractory to Sodium Bicarbonate Administration

ABSTRACT

Propafenone is a Class Ic antidysrhythmic agent, used in the management of atrial fibrillation. This is also a calcium channel and a weak beta blocker. The conventional therapy of hypotension induced by propafenone overdose includes fluid resuscitation followed by inotropic support. NaHCO3 is considered to be the treatment of choice. We report a case of successful insulin therapy for propafenone-induced hypotension unresponsive to NaHCO3. A 41-year-old woman with a prior medical history of atrial fibrillation presented to the ED after ingesting 4500 mg of propafenone, prescribed for her atrial fibrillation treatment. On initial examination, she was alert with O2 saturation of 96% and normal vital sign. Fifteen minutes later, her electrocardiogram revealed polymorphic ventricular tachycardia and then changed to ventricular fibrillation. When CPR was stopped, her BP was 70/40 mmHg, HR was 68 beats/min with wide QRS complex. Normal saline and inotropics were administered rapidly to improve hypotension. And we injected NaHCO3. Her blood pH was kept between 7.45 and 7.55. But, BP was not improved. Refractory to the conventional therapy for sodium channel blocker toxicity, we decided to try insulin treatment, considering properties of propafenonen having beta and calcium channel blocking effect. We administered short-acting insulin. Her blood glucose level was kept euglycemia by continuous 5% dextrose infusions and tried to keep serum potassium normal range. Thirty minutes after adminstering insulin, her SBP was checked at 100 mmHg. She was discharged 8 days post-ingestion without further complications. Insulin must be considered in severe hypotension induced by propafenone overdose unresponsive to other conventional therapy.