Managing Beta-Blocker Overdose in the ED: Pressors, Insulin, and Glucagon – Oh My! 

-Case-

EMS brings in a 52-year-old man found unresponsive at home with an empty bottle of an unknown medication nearby. His wife reports he had been complaining of dizziness and weakness earlier in the day. On arrival, our patient is bradycardic at 38 bpm, hypotensive at 75/40 mmHg, and minimally responsive. His ECG shows sinus bradycardia with a prolonged PR interval.

With this presentation in mind, what medication are we worried was in his empty pill bottle?

-Evaluation-

Beta-blocker overdose shuts down sympathetic tone, leading to bradycardia, hypotension, and in severe cases, shock. Non-selective beta-blockers (e.g., propranolol, carvedilol) can also cause CNS depression and seizures due to their lipophilic nature, giving them the ability to cross the blood-brain-barrier.

Notably, BB overdoses can cause AV block and cardiogenic shock. In other cases, especially in pediatric overdoses, these symptoms along with hypoglycemia can further clue you in to BB toxicity. There are only a select few medications that will cause hypotensive bradycardia – make sure to be thorough with your H+P and lean on collateral to find out the potential cause!

The diagnosis of BB toxicity is clinical, but an ECG displaying bradycardia, a prolonged PR interval, and possible AV block can raise our suspicion. In addition, hypoglycemia and metabolic acidosis are also common with this medication class.

-Management-

1. Supportive care: think IV Fluids + atropine (may be ineffective but worth trying for bradycardia) with pressors (Norepinephrine, Epinephrine) for hypotension if refractory
2. First-line antidote: high-dose insulin + dextrose! In this case, it enhances cardiac metabolism and contractility.
3. Glucagon: stimulates cAMP production, bypassing beta-blockade; high doses of this medication can cause GI discomfort, so make sure to also pre-treat with antiemetics!
4. Lipid emulsion therapy has some utility in more lipophilic beta blockers; pacing or ECMO are useful in severe or refractory cases.

-Fast Facts-

• Bradycardia + hypotension + AV block = think beta-blocker toxicity!
• High-dose insulin + dextrose = first-line therapy
• Propranolol is considered the worst offender (classic BB toxicity sx + seizures, coma, wide QRS)
• Consider lipid therapy or ECMO for severe cases

Beta-blocker toxicity can rapidly spiral into cardiovascular collapse. In these cases, along with atropine and pressors, high-dose insulin therapy can be life-saving. We may not always know exact which medications a patient takes, but keep the signs in mind and act fast when there is suspicion for beta blocker toxicity!

Want to learn more? Read our in-depth study guide about beta blocker overdose!

Cheers,

Tamir Zitelny, MD