What is the appropriate emergency management for a patient with suspected beta‑blocker overdose?

Emergency Management of Beta-Blocker Overdose

For suspected beta-blocker overdose with hemodynamic instability, immediately initiate high-dose insulin euglycemia therapy as first-line treatment alongside vasopressor support, with glucagon as an equally reasonable alternative, reserving ECMO for refractory shock. 1, 2, 3

Initial Stabilization

• Establish continuous cardiac monitoring, secure IV access, and assess airway protection needs following standard BLS/ACLS protocols 1, 2
• Obtain 12-lead ECG to identify QRS widening (predictive of severe ventricular arrhythmias), bradycardia, and conduction blocks 4
• Consider gastric decontamination with activated charcoal if presentation is within 1-2 hours of ingestion, though evidence for mortality benefit is limited 5
• For atenolol or sotalol overdose specifically, hemodialysis may be reasonable given their water-solubility and dialyzability 1, 6

First-Line Pharmacologic Therapy

High-dose insulin euglycemia therapy is the most strongly recommended intervention for refractory shock, with Class 1 evidence from the American Heart Association. 1, 2

High-Dose Insulin Protocol:

• Initial bolus: 1 U/kg regular insulin IV with simultaneous 0.5 g/kg dextrose bolus 1
• Continuous infusion: 0.5-1 U/kg/hour insulin (titrate up to 10 U/kg/hour as needed) with 0.5 g/kg/hour dextrose 1, 3
• Target glucose: 100-250 mg/dL (5.5-14 mmol/L) with monitoring every 15 minutes initially 1
• Mechanism: Improves myocardial energy utilization and contractility independent of beta-receptor status 1, 3
• Central line required: For dextrose concentrations >10% 1, 7

Glucagon (Equally Reasonable Alternative):

• Initial bolus: 3-10 mg IV over 3-5 minutes 1
• Continuous infusion: 3-5 mg/hour (0.05-0.10 mg/kg/hour), titrated to hemodynamic response 1, 3
• Mechanism: Bypasses blocked beta-receptors by directly activating adenyl cyclase, increasing heart rate and contractility 3, 8
• Supply planning: May require >100 mg in 24 hours; ensure adequate glucagon availability early 1
• Airway protection: Mandatory before administration due to high risk of vomiting 1, 3

Vasopressor Support

Vasopressors are recommended as initial therapy for hypotension (Class 1 evidence) and should be started immediately while preparing insulin or glucagon. 1, 2

• Norepinephrine: Preferred for vasoplegic shock to increase blood pressure 2, 3
• Epinephrine: Use to increase contractility and heart rate; more effective than dopamine for refractory hypotension 1, 3
• High-dose catecholamines: May be required but often insufficient alone due to severe beta-receptor blockade 1, 5

Second-Line Therapies

Calcium Administration (Class 2b):

• Dose: 0.3 mEq/kg calcium (0.6 mL/kg of 10% calcium gluconate or 0.2 mL/kg of 10% calcium chloride) IV over 5-10 minutes 1
• Continuous infusion: 0.3 mEq/kg/hour, titrated to hemodynamic response 1
• Monitoring: Serum ionized calcium levels; avoid exceeding 1.5-2 times upper limit of normal 1
• Central access required: For sustained infusions, especially in children 1
• Evidence: Weaker for beta-blockers compared to calcium channel blockers 3

Atropine (Class 2b):

• Dose: 0.5-1.0 mg IV every 3-5 minutes up to 3 mg total 1
• Pediatric: 0.02 mg/kg 1
• Indication: May be reasonable for symptomatic bradycardia, though often ineffective in severe overdose 1, 6, 4

Temporary Cardiac Pacing (Class 2b):

• Consider transcutaneous or transvenous pacing for refractory bradycardia or heart block 1, 6
• Particularly useful in sotalol toxicity to prevent arrhythmias 5

Rescue Therapy for Refractory Cases

ECMO should be considered for cardiogenic shock refractory to maximal pharmacological therapy (Class 2a evidence). 1, 2, 3

• Indication: Persistent shock despite high-dose insulin, glucagon, vasopressors, and calcium 1
• Evidence: Case series and observational studies show improved survival in severe cardiogenic shock or cardiac arrest 1, 5
• Early consultation: Contact medical toxicologist and ECMO team early in deteriorating patients 1

Critical Monitoring Requirements

Metabolic Monitoring with High-Dose Insulin:

• Glucose: Every 15 minutes during initial titration, then hourly once stable 1, 3
• Potassium: Frequent monitoring; insulin causes intracellular shift 1
• Target potassium: 2.5-2.8 mEq/L (avoid aggressive repletion—can cause asystole) 1, 7
• Volume status: Monitor for fluid overload from dextrose infusions 3

Hemodynamic Monitoring:

• Continuous blood pressure, heart rate, and cardiac rhythm monitoring 1, 2
• Consider arterial line for continuous blood pressure monitoring 1
• Urine output monitoring with indwelling catheter 1

Common Pitfalls to Avoid

• Do NOT use lipid emulsion therapy: Class 3 (no benefit) recommendation from American Heart Association for beta-blocker poisoning 1, 2
• Do NOT aggressively replace potassium: Target 2.5-2.8 mEq/L to prevent fatal arrhythmias during insulin therapy 1, 7
• Do NOT underdose glucagon: Requires much higher doses than typical hypoglycemia treatment (3-10 mg vs 1 mg) 3, 8
• Do NOT delay escalation: If initial therapy fails within 30-60 minutes, rapidly escalate to combination therapy rather than waiting 3
• Do NOT use dopamine preferentially: Epinephrine and norepinephrine are more effective; dopamine may decrease glucagon effectiveness 1

Special Considerations

Drug-Specific Factors:

• Propranolol and sotalol: May cause QRS/QT prolongation and seizures; have threshold doses beyond which symptoms worsen dramatically 4, 9
• Atenolol and sotalol: Water-soluble; consider hemodialysis for massive overdoses 1, 6, 5
• Sustained-release formulations: Expect prolonged toxicity requiring extended monitoring and treatment 1

Co-Ingestions:

• With calcium channel blockers: Particularly dangerous; one fatality reported with bisoprolol-verapamil combination 9
• With other antihypertensives or CNS depressants: Increased risk of severe toxicity and mortality 9