(1690) High-Dose Insulin-Euglycemic Therapy Titrated to Mean Arterial Pressure in Amlodipine Overdose

Introduction: Calcium channel blocker overdose can induce cardiogenic shock by suppressing cardiac inotropy and chronotropy. High-dose insulin-euglycemic therapy (HIET) delivers doses of insulin on the order of 1-10 U/kg/hr and is the inotrope of choice in patients with evidence of myocardial dysfunction. We report a case wherein high doses of insulin and dextrose were titrated to markers of perfusion in a young woman presenting after amlodipine overdose.

Description: A 23-year-old woman with no significant past medical history presented after ingesting ~400 mg of amlodipine in a suicide attempt. She developed hypotension refractory to fluids, calcium gluconate, norepinephrine, and vasopressin, but sensitive to HIET. She also developed pulmonary edema due to amlodipine-induced pulmonary vasodilation and isotonic fluid administration necessitating intubation.

In the subsequent hours, the insulin infusion was increased to a maximum 10 U/kg/hr (680 U/hr) to sustain adequate perfusion while norepinephrine and vasopressin were weaned. Insulin was stopped on hospital day four, and the patient was extubated the same day. She was later transferred to the medicine service, where she completed a full recovery before transfer to inpatient psychiatry.

Discussion: HIET is the inotrope of choice in cases of severe calcium-channel blocker overdose. Insulin can also be used in patients who respond to vasopressors as a pressor-sparing adjunct, preventing complications such as limb ischemia and cardiac dysrhythmias. Insulin induces direct inotropic effects on myocardium by binding to sarcolemmal insulin receptors and increasing calcium sensitivity. CCB-induced pancreatic beta cell dysfunction leads to hypoinsulinemia, impairing the dysfunctional myocardium’s normal response to stress - a transition from fatty acid to carbohydrate metabolism. HIET enables this transition, further improving inotropy. Our patient's shock was refractory to fluid resuscitation and vasopressors. Preparing concentrated insulin drips and D50 infusions required a significant marshalling of pharmacy resources – pharmacists and intensivists alike should be aware of the required elements of HIET and have protocols in place to meet these needs.