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

Diagnosis

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

Work-Up

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

DDx

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

Management

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

If IV fluid and atropine are not sufficient then consider:

Glucagon

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

High dose insulin and glucose

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

Vasopressors

1. Consider if all of above has failed
2. Epinephrine
   1. Adult: Start 1 mcg/min and titrate to MAP=60
   2. 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

1. IV 20% Intralipid at 1.5 mL/kg Bolus
2. Bolus could be repeated 1-2 times if persistent systole
3. Infusion of 0.25 mL/kg/min for 30-60 minutes
4. 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)
   1. Infusion rate could be increased if the BP declines

Hemodialysis

1. Only effective for Nadolol, sotalol, and atenolol

Disposition

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

Source

1. http://www.lipidrescue.org/
2. EB Medicine May/Jun 2014 Vol 4, No 3