What is the first-line treatment for beta blocker overdose?

First-Line Treatment for Beta Blocker Overdose

High-dose insulin therapy with glucose supplementation is the first-line treatment for beta blocker overdose refractory to or in conjunction with vasopressor therapy. 1, 2

Treatment Algorithm

Initial Management:

1. Vasopressors (Class 1, C-LD evidence)

   • Immediately administer for hypotension due to beta blocker poisoning
   • Options include epinephrine, norepinephrine, dopamine
   • Titrate to effect based on blood pressure response

2. High-dose insulin therapy (Class 1, B-NR evidence)

   • Initial bolus: 1 U/kg IV
   • Continuous infusion: Start at 1 U/kg/hour
   • Titrate based on clinical response (up to 10 U/kg/hour has been reported)
   • Co-administer with dextrose to maintain euglycemia
   • Monitor potassium levels (risk of hypokalemia)

3. Glucagon (Class 2a, C-LD evidence)

   • Bolus: 5-10 mg IV over 3-5 minutes
   • Follow with continuous infusion: 1-5 mg/hour
   • Caution: May cause vomiting (protect airway)

For Refractory Cases:

1. Atropine (Class 2b, C-LD evidence)

   • 0.5-1 mg IV for symptomatic bradycardia
   • Often has limited efficacy in beta-blocker overdose

2. Calcium administration (Class 2b, C-LD evidence)

   • Calcium chloride or calcium gluconate IV
   • May repeat every 10-20 minutes for 3-4 doses if beneficial

3. VA-ECMO (Class 2a, C-LD evidence)

   • Consider for life-threatening poisoning with cardiogenic shock refractory to pharmacological interventions
   • Early consultation with ECMO team recommended

4. Hemodialysis (Class 2b, C-LD evidence)

   • Consider only for life-threatening atenolol or sotalol poisoning
   • Not effective for lipophilic beta blockers like propranolol

Evidence Analysis

The 2023 American Heart Association focused update on management of patients with life-threatening toxicity provides the strongest and most recent evidence for treatment recommendations 1. This guideline gives a Class 1, B-NR recommendation for high-dose insulin as first-line therapy for hypotension due to beta blocker poisoning, indicating the highest level of recommendation with moderate-quality evidence 1.

While earlier guidelines from 2020 suggested multiple potential first-line options 1, the more recent 2023 update provides clearer direction with stronger evidence supporting high-dose insulin therapy 1. This is further supported by Praxis Medical Insights which also identifies high-dose insulin as the first-line treatment 2.

High-dose insulin improves inotropy in cardiogenic shock from beta blocker poisoning through three main mechanisms: increased inotropy, increased intracellular glucose transport, and vascular dilatation 3. A large cohort study reported favorable outcomes with lower rates of vasoconstrictive complications compared to vasopressor-only therapy 1.

Monitoring and Adverse Effects

• Blood glucose: Monitor frequently (every 15-30 minutes initially, then every 1-2 hours)
• Potassium: Monitor regularly as insulin therapy can cause hypokalemia
• Hemodynamic parameters: Continuous cardiac monitoring
• Neurobehavioral status: Assess for improvement in mental status

The major adverse effects of high-dose insulin therapy are hypoglycemia and hypokalemia 3. Glucose supplementation will likely be required throughout therapy and for up to 24 hours after discontinuation of high-dose insulin 3.

Common Pitfalls and Caveats

1. Delayed initiation of high-dose insulin: Many clinicians start with conventional therapies and delay insulin, which has superior efficacy in severe poisoning.

2. Inadequate dosing: Traditional insulin dosing is insufficient; high-dose regimens are required for toxicity management.

3. Fear of hypoglycemia: This concern often leads to underdosing of insulin. With proper glucose monitoring and supplementation, hypoglycemia can be effectively managed.

4. Intravenous lipid emulsion therapy: The 2023 AHA guidelines specifically state this is not likely to be beneficial for life-threatening beta blocker poisoning (Class 3: No Benefit) 1.

5. Overreliance on atropine: While commonly used for bradycardia, atropine often has limited efficacy in beta blocker overdose and should not delay more effective therapies 1.

High-dose insulin therapy represents a paradigm shift from traditional cardiovascular support measures, but has emerged as the most effective treatment based on current evidence for improving survival in severe beta blocker toxicity 3.