High-Dose Insulin Therapy for Beta-Blocker Overdose
For beta-blocker overdose with refractory shock, administer an initial bolus of 1 unit/kg regular insulin IV, followed by a continuous infusion of 1 unit/kg/hour, with concurrent dextrose 0.5 g/kg/hour to maintain euglycemia. 1
Dosing Protocol
The most recent 2020 AHA guidelines establish high-dose insulin as a Class 2a recommendation (reasonable to administer) for beta-blocker overdose with refractory shock 1. The standardized regimen is:
Initial Bolus and Infusion
- Insulin bolus: 1 unit/kg IV regular insulin
- Insulin infusion: Start at 1 unit/kg/hour, titrate up as needed for hemodynamic response (can escalate to 10 units/kg/hour in refractory cases)
- Dextrose bolus: 0.5 g/kg IV (given with insulin bolus)
- Dextrose infusion: 0.5 g/kg/hour, titrated to maintain glucose 100-250 mg/dL 2
Critical Monitoring Requirements
Glucose monitoring: Every 15 minutes initially during dextrose titration, then hourly once stable 2. Concentrated dextrose solutions >10% require central venous access 2.
Potassium monitoring: Insulin shifts potassium intracellularly, causing predictable hypokalemia. Target potassium levels of 2.5-2.8 mEq/L to avoid overly aggressive repletion, as animal studies showed asystole with aggressive potassium replacement 2. Monitor potassium frequently and replace cautiously.
Mechanism and Evidence Base
High-dose insulin improves myocardial energy utilization in beta-blocker toxicity, enhancing contractility and hemodynamic stability 2. While no controlled human trials exist, animal studies demonstrate superiority over calcium, glucagon, epinephrine, and vasopressin for survival 3. Multiple case reports and series show success rates of 80-100% 4, 3.
Treatment Algorithm
First-Line Therapies (initiate simultaneously)
- IV fluids: Aggressive volume resuscitation
- Atropine: For bradycardia (0.02 mg/kg, minimum 0.1 mg, maximum 0.5 mg per dose)
- High-dose insulin: As detailed above 1, 5
- Glucagon: 3-10 mg IV bolus over 3-5 minutes, then 3-5 mg/hour infusion (Class 2a recommendation) 2
Second-Line Considerations
- Calcium: 0.3 mEq/kg (0.6 mL/kg of 10% calcium gluconate or 0.2 mL/kg of 10% calcium chloride) over 5-10 minutes, then infusion at 0.3 mEq/kg/hour (Class 2b recommendation—weaker evidence than insulin) 2
- Vasopressors: Norepinephrine or epinephrine for persistent hypotension
Rescue Therapies for Refractory Cases
- Escalate insulin: Up to 10-22 units/kg/hour has been reported safely 3, 6
- Lipid emulsion therapy: Consider in refractory shock 2
- ECMO: For shock refractory to all pharmacologic therapy 1
Common Pitfalls
Starting too low: The 2010 guidelines suggested starting at 0.5 units/kg/hour 2, but the 2020 guidelines and clinical experience support starting at 1 unit/kg/hour 1, 5. Don't be timid—escalate aggressively if hemodynamics don't improve.
Inadequate glucose monitoring: Hypoglycemia is the primary risk. Initial 15-minute glucose checks are mandatory, not optional 2.
Aggressive potassium repletion: Resist the urge to aggressively correct mild hypokalemia (2.5-2.8 mEq/L is acceptable) as this represents intracellular shift, not true depletion 2.
Delaying insulin therapy: Earlier case reports positioned insulin as "last resort," but current evidence supports it as first-line therapy alongside glucagon 7, 3, 8. Don't wait for conventional therapies to fail completely.
Airway protection with glucagon: Glucagon causes nausea and vomiting—protect the airway before administration if the patient has altered mental status 2.
Duration of Therapy
Continue high-dose insulin until hemodynamic stability is achieved and vasopressor requirements decrease. Median duration in case series is approximately 23 hours (range 1-136 hours) 9. Monitor for resedation and hypoglycemia for up to 24 hours after discontinuation 3.