β-Blocker and Calcium Channel Blocker Poisoning: High-Dose Insulin/Glucose Therapy

Abstract

Overdoses of b-blockers and calcium channel blockers can produce significant morbidity and mortality, and conventional therapies often do not work as treatments for these poisonings. High-dose insulin/glucose therapy has been successful in reversing the cardiotoxic effects of these drugs in cases where the standard therapies have failed, and it appears to be relatively safe. Many successes have been well documented, but the clinical experience consists of case reports, the mechanisms of action are not completely understood, and guidelines for use of the therapy are empirically derived and not standardized. Regardless of these limitations, high-dose insulin/glucose therapy can be effective, it is often recommended by clinical toxicologists and poison control centers, and critical care nurses should be familiar with when and how the therapy is used. b-Blocker and Calcium Channel Blocker Poisoning: High-Dose Insulin/ Glucose Therapy H igh-dose insulin/glucose therapy, which is also called hyperinsulinemic/euglycemic therapy or insulin-dextrose therapy, has received considerable attention as a treatment for overdoses of b-blockers and calcium channel blockers that are refractory to conventional therapies. Clinical experience using high-dose insulin/glucose to treat cardiotoxic poisonings in humans dates to 1999, 1 and animal experiments before that time provided the theoretical background and the impetus for extension of its use to treat calcium channel blocker overdoses and then b-blocker overdoses.Despite many articles in medical publications and 15 years of clinical experience with its use, questions remain about how high-dose insulin/glucose therapy works and when and for whom this therapy should be applied. In addition, the dosing guidelines are not standardized. However, high-dose insulin/ glucose therapy is commonly used and often recommended for treating b-blocker and calcium channel blocker poisoning, and critical care nurses should be familiar with the therapy.

Clinical Pearls in Medical Toxicology: Updates Ranging From Decontamination to Elimination

“…It should be noted that although HIET has been more extensively studied in the treatment of CCB poisoning, the pathophysiology and therapeutic principles apply to BB intoxication as well. 16,17 The onset of HIET is reported to occur between 15 and 60 minutes; therefore, simultaneous institution of other therapies to maintain heart rate and BP is generally required. 11 The dosing protocol most widely described includes administration of a regular insulin bolus of 1 U/kg followed by a continuous infusion of 0.5 to 10 U/kg/h.…”

“…The concentration of the insulin infusion should be 1 U/mL but may be increased to 10 U/mL in patients who cannot tolerate a large volume load. 16 One of the feared complications associated with HIET includes hypoglycemia. It should be noted that not all patients will require supplemental dextrose.…”

“…11,15,19 The average duration of infusion has been 24 to 31 hours and up to 116 hours in one case. 16,19,20 Although a lack of benefit has been reported due to delayed administration and/or ineffective dosing, 15 increasing number of cases along with clinical experience has found HIET to be effective in the management of CCB and BB overdose. As such, current guidelines suggest high-dose insulin therapy (along with intravenous [IV] fluids, IV calcium, or vasopressors) as first-line therapy for symptomatic CCB-poisoned patients, if evidence of myocardial dysfunction (defined as decreased myocardial contractility seen on the cardiac ultrasound or cardiac index less than 2.2 L/min/m 2 ) is suspected.…”

“…The concentration of the insulin infusion should be 1 U/mL but may be increased to 10 U/mL in patients who cannot tolerate a large volume load. 16…”

“…11,15,19 The average duration of infusion has been 24 to 31 hours and up to 116 hours in one case. 16,19,20…”