Beta-blocker toxicity

Background

• Coingestion with Calcium Channel Blockers, Tricyclic Antidepressants, and Antipsychotics increases mortality
• Agents with membrane-stabilizing activity are esp lethal
  • Prolongs QT > dysrhythmias
    • Propranolol
    • Sotalol

Clinical Features

• Cardiac
  • Bradycardia
  • Hypotension
  • Ventricular dysrhythmias
• CNS
  • Mental status change
    • Delirium, coma
  • Seizure (esp w/ propranolol)
• Other
  • Hypoglycemia (uncommon in adults)
  • Bronchospasm (uncommon)
  • Hypothermia

Differential Diagnosis

• Calcium-channel blockers
  • Unlikely to cause CNS changes
  • Hyperglycemia is more common
• Digoxin
  • Nausea/vomiting is more common
• Clonidine
  • Miosis, somnolence
• Cholinergic agents
  • SLUDGE

Diagnosis

1. ECG
   • PR prolongation
   • Bradycardia
   • QT Prolongation
   • Any bradydysrhythmia
2. Glucose
3. Chemistry
   • Creatinine (esp with atenolol)

Management

1. Consider activated charcoal if present within 2 hr of ingestion
2. Symptomatic bradycardia
   • Atropine 0.5-1mg q3-5min up to 0.04mg/kg
3. Hypotension
   • IV fluids
4. Hypoglycemia
   • Adult - D50
   • Ped - 2.5mL/kg of D10

If IV fluid and atropine are not sufficient then consider

Glucagon

• Half-life is 20min
• Consider concurrent administration of ondansetron (causes n/v)
• Adult: 5mg IV bolus over one minute
• Ped: 50mcg/kg
• Rebolus if no response after 10min
• Effects persist for 10-15 min
• If effective start infusion at:
  • Adult: 2-5mg/hr
  • Ped: 70mcg/kg/hr

High dose insulin and glucose

• Augments myocardial contraction
• Regular Insulin 1 Unit/kg IV Bolus accompanied by 0.5g/kg dextrose
• Regular insulin 1Unit/kg/hr Drip
• D50W drip at 0.1-0.2gram/kg/hr

Vasopressors

• Consider to be added as adjunctive therapy to all other therapies. Toxcity can also be manage vasopressors alone
• Epinephrine
  • Adult: Start 1 mcg/min and titrate to MAP=60
  • Ped: Start 0.1mcg/kg/min

Intralipid Therapy

Draw all labs prior to infusion. Support as an antidote comes from animal studies and case reports

• IV 20% Intralipid at 1.5 mL/kg Bolus
  • Bolus could be repeated 1-2 times if persistent asystole
  • Followed by infusion of 0.25 mL/kg/min for 30-60 minutes or until hemodynamic stability achieved
• if responsive to bolus initiate infusion at 0.25 mL/kg/min for 1hr (e.g. about 600 mL over 30 minutes in a 70kg adult)
  • Infusion rate could be increased if the BP declines

Hemodialysis

• Only effective for Nadolol, sotalol, and atenolol

Disposition

• Admit all symptomatic patients
• Admit all sotalol ingestions (long half-life)
• Observe all others for ~ 6hr

See Also

• Beta blockers