What is the treatment for a patient with a beta blocker overdose, particularly one who is hemodynamically unstable with bradycardia and hypotension?

Treatment of Beta-Blocker Overdose

For hemodynamically unstable patients with beta-blocker overdose presenting with bradycardia and hypotension, initiate high-dose insulin euglycemia therapy (1 U/kg bolus with 0.5 g/kg dextrose, then 1 U/kg/hour infusion) and IV glucagon (3-10 mg bolus over 3-5 minutes, then 3-5 mg/hour infusion) as first-line pharmacologic interventions, with ECMO reserved for refractory shock. 1, 2

Immediate Stabilization

• Establish continuous cardiac monitoring, secure IV access (preferably central if prolonged therapy anticipated), and assess airway protection following standard BLS/ACLS protocols 1, 2
• Obtain baseline labs including glucose, potassium, ionized calcium, and renal function 1
• Consider activated charcoal (1-2 g/kg) if presentation is within 1-2 hours of ingestion and airway is protected 1

First-Line Pharmacologic Therapy

The American College of Cardiology and American Heart Association provide Class 2a recommendations for both high-dose insulin and glucagon as reasonable first-line therapies for refractory shock 1, 2:

High-Dose Insulin Euglycemia Therapy (HIET)

• Administer 1 U/kg regular insulin IV bolus with simultaneous 0.5 g/kg dextrose bolus 1, 2
• Follow with continuous infusion of 1 U/kg/hour insulin (range 0.5-1 U/kg/hour) 1
• Co-administer dextrose infusion (0.5 g/kg/hour) to maintain euglycemia 1
• HIET is the most effective therapy for restoring hemodynamic stability in severe beta-blocker toxicity by improving myocardial contractility and cardiac output 1, 3
• Monitor glucose every 15 minutes initially, then hourly once stable, targeting 100-250 mg/dL 1, 2
• Monitor potassium levels closely as hypokalemia is a common adverse effect 1, 3

Glucagon

• Administer 3-10 mg IV bolus over 3-5 minutes, followed by continuous infusion of 3-5 mg/hour 1, 2
• Glucagon bypasses blocked beta-adrenergic receptors by directly activating hepatic adenyl cyclase, increasing heart rate and myocardial contractility independent of beta-receptor status 1, 4
• Extensive clinical experience shows consistent increases in heart rate during beta-blocker overdose 1, 4
• Monitor for nausea and vomiting, which are common side effects 1
• Be aware of potential tachyphylaxis with prolonged use 1

Second-Line Therapies

Vasopressor Support

• Use norepinephrine to increase blood pressure in vasoplegic shock 1, 2
• Use epinephrine to increase contractility and heart rate 1, 2
• Catecholamines, inotropes, and vasopressors provide survival benefit and improved haemodynamics in beta-blocker toxicity 3

Calcium Administration

• The American Heart Association gives calcium a Class 2b recommendation for beta-blocker overdose (weaker evidence compared to calcium channel blocker toxicity) 1, 2
• May be considered in refractory shock, though evidence is limited 2, 3

Rescue Therapy for Refractory Cases

Extracorporeal Membrane Oxygenation (ECMO)

• Consider ECMO for shock refractory to all pharmacological interventions (Class 2b recommendation from the American College of Cardiology) 1, 2
• ECMO was associated with improved survival in patients with severe cardiogenic shock or cardiac arrest in observational studies 3
• The American Heart Association supports ECMO use for refractory shock from reversible causes such as drug toxicity 2

Critical Monitoring Parameters

• Continuous cardiac telemetry for rhythm and conduction abnormalities 1
• Arterial line for blood pressure monitoring in shock states 1
• Glucose monitoring every 15 minutes initially during HIET, then hourly once stable 1, 2
• Potassium levels monitored closely during HIET 1, 3
• Ionized calcium levels if calcium infusions are used 1

Common Pitfalls to Avoid

• Do not underdose glucagon - use the full 3-10 mg bolus, not the typical 1-2 mg doses used for hypoglycemia 1
• Do not delay escalation to high-dose insulin if initial therapies are failing 1
• Avoid lipid emulsion therapy - evidence shows variable and inconsistent response in beta-blocker overdose 1, 3
• Do not abruptly withdraw beta-blocker therapy in patients on chronic therapy, as this can lead to clinical deterioration 2

Special Considerations

• Consult medical toxicology or poison control center (1-800-222-1222) for all beta-blocker overdoses to guide therapy 1
• For water-soluble beta-blockers like atenolol in massive overdose, hemodialysis may assist elimination, though survival benefit is not established 3
• Temporary overdrive cardiac pacing may be useful for arrhythmias in sotalol toxicity specifically 3