Use of a Porcine Model to Evaluate the Risks and Benefits of Vasopressors in Propranolol Poisoning

Beta-blocker and calcium-channel blocker toxicity: current evidence on evaluation and management

Beta-blocker and calcium-channel blocker overdoses are associated with severe morbidity and mortality; therefore, it is important to recognize and appropriately treat individuals with toxicity. The most common clinical findings in toxicity are bradycardia and hypotension. In addition to supportive care and cardiac monitoring, specific treatment includes administration of calcium salts, vasopressors, and high-dose insulin euglycaemia treatment. Other advanced treatments (e.g. ECMO) may be indicated depending on the severity of toxicity and specific agents involved.

Use of Concentrated Insulin in the Management of Calcium Channel Blocker Overdose: A Case Report

INTRODUCTION

Hyperinsulinemia-euglycemia therapy [HIE] is a first line therapy recommended in symptomatic calcium channel blocker overdose patients. HIE, particularly if administered in concentrations typically used for glycemic control, would result in a substantial amount of hypotonic fluid administration, which places patients at risk of volume overload. Therefore, it may be beneficial to utilize a concentrated insulin as a strategy to mitigate fluid overload risks. We report the case of a 73 years old, 69.9 kg female, who presented to the emergency department after an accidental ingestion of 70 mg amlodipine and was treated with HIE utilizing a uniquely concentrated insulin infusion.

CASE PRESENTATION

HIE at 10 units/kg/hr. was used for approximately 17 hours. Insulin was changed from a 1 unit/mL concentration to 16 unit/mL. Dextrose 10% infusion was initiated up to a max of 650 mL/hr. and norepinephrine infusion up to a max of 10 mcg/min.

DISCUSSION

Approximate fluid requirements from the 16 unit/mL concentration of insulin totaled 1 L as compared to a 1 unit/mL concentration which would have required 17 L, a total savings of 16 L. This savings potentially decreased the risk of cerebral or pulmonary edema associated with fluid overload.

CONCLUSION

Use of a concentrated insulin in the setting of a calcium channel blocker or beta blocker overdose provides a unique strategy to mitigate the effects associated with fluid overload.

Hemodynamic Effects of Cardiovascular Medications in a Normovolemic and Hemorrhaged Yorkshire-cross Swine Model

The Yorkshire-cross swine model is a valuable translational model commonly used to study cardiovascular physiologyand response to insult. Although the effects of vasoactive medications have been well described in healthy swine, the effects of these medications during hemorrhagic shock are less studied. In this study, we sought to expand the utility of the swine model by characterizing the hemodynamic changes that occurred after the administration of commonly available vasoactive medications during euvolemic and hypovolemic states. To this end, we anesthetized and established femoral arterial,central venous, and pulmonary arterial access in 15 juvenile Yorkshire-cross pigs. The pigs then received a series of rapidlymetabolized but highly vasoactive medications in a standard dosing sequence. After completion of this sequence, each pigunderwent a 30-mL/kg hemorrhage over 10 min, and the standard dosing sequence was repeated. We then used standard statisticaltechniques to compare the effects of these vasoactive medications on a variety of hemodynamic parameters betweenthe euvolemic and hemorrhagic states. All subjects completed the study protocol. The responses in the hemorrhagic state wereoften attenuated or even opposite of those in the euvolemic state. For example, phenylephrine decreased the mean arterialblood pressure during the euvolemic state but increased it in the hemorrhagic state. These results clarify previously poorlydefined responses to commonly used vasoactive agents during the hemorrhagic state in swine. Our findings also demonstratethe need to consider the complex and dynamic physiologic state of hemorrhage when anticipating the effects of vasoactivedrugs and planning study protocols.

Persistent Hyperinsulinemia Following High-Dose Insulin Therapy: A Case Report

INTRODUCTION

Overdoses of beta-adrenergic antagonists and calcium channel antagonists represent an uncommonly encountered but highly morbid clinical presentation. Potential therapies include fluids, calcium salts, vasopressors, intravenous lipid emulsion, methylene blue, and high-dose insulin. Although high-dose insulin is commonly used, the kinetics of insulin under these conditions are unknown.

CASE REPORT

We present a case of a 51-year-old male who sustained a life-threatening overdose after ingesting approximately 40 tablets of a mixture of amlodipine 5 mg and metoprolol tartrate 25 mg. Due to severe bradycardia and hypotension, he was started on high-dose insulin (HDI) therapy; this was augmented with epinephrine. Despite the degree of his initial shock state, he ultimately recovered, and HDI was discontinued. Insulin was infused for a total of approximately 37 hours, most of which was dosed at 10 U/kg/hour; following discontinuation, serial serum insulin levels were drawn and remained at supraphysiologic levels for at least 24 hours and well above reference range for multiple days thereafter.

CONCLUSION

The kinetics of insulin following discontinuation of high-dose insulin therapy are largely unknown, but supraphysiologic insulin levels persist for some time following therapy; this may allow for simple discontinuation rather than titration of insulin at the end of therapy. Dextrose replacement is frequently needed; although the duration is often difficult to predict, prolonged infusions may not be necessary.