Beta-blocker toxicity

Background

• Coingestion with CCB, cyclics, and neuroleptics 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)

Work-Up

1. ECG
   1. PR prolongation
   2. Bradycardia
   3. QT prolongation
   4. Any bradydysrhythmia
2. Glucose
3. Chemistry

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:

1. 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
2. High dose insulin and glucose
   1. Augments myocardial contraction
   2. Regular Insulin 1 Unit/kg IV Bolus
   3. Regular insulin 1Unit/kg/hr Drip
   4. D50W drip at 0.1-0.2gram/kg/hr 
3. 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
4. Fat Emulsion Therapy - "Intra-lipid"
   1. IV 20% Intralipid at 1.5 mL/kg Bolus
      1. Bolus could be repeated 1-2 times if persistent asystole
   2. if responsive to bolus initiate infusion at 0.25 mL/kg/min for 1hr then R/A
      1. Infusion rate could be increased if the BP declines
5. 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. Rosen's
2. http://emedicine.medscape.com/article/813342-overview
3. http://www.lipidrescue.org/