What is the appropriate emergency management for a patient with suspected propranolol overdose?

Propranolol Overdose: Emergency Management

Immediate Resuscitation

For propranolol overdose with cardiac arrest, follow standard BLS/ACLS protocols with high-quality CPR as the absolute priority—there are no specific antidotes proven effective during cardiac arrest. 1

• Initiate chest compressions and defibrillation per standard algorithms; propranolol's sodium channel blocking properties may cause wide-complex dysrhythmias requiring electrical cardioversion. 1, 2
• Secure the airway early and provide bag-mask ventilation or endotracheal intubation, as CNS depression can be severe even before overt cardiovascular collapse develops. 1, 3
• Administer atropine (0.5-1 mg IV) before gastric decontamination procedures (lavage, emetics) to prevent vagally-mediated cardiovascular collapse in the setting of beta-blockade. 4

Gastric Decontamination

• Evacuate gastric contents if ingestion was recent, using activated charcoal if the patient can protect their airway or after intubation. 5
• Critical pitfall: Never induce emesis or perform gastric lavage without pre-treatment with atropine, as vagal stimulation combined with beta-blockade can precipitate sudden cardiovascular collapse. 4

Hemodynamic Support for Refractory Shock

First-Line Vasopressor Therapy

For hypotension refractory to IV fluid boluses (10-20 mL/kg normal saline), use high-dose epinephrine or norepinephrine infusions rather than dopamine, as beta-receptor blockade renders dopamine less effective. 1

• Epinephrine is preferred because it can overcome beta-receptor blockade at high doses, though it may provoke uncontrolled hypertension in some cases. 5

Glucagon Therapy

Administer glucagon as the primary antidote for severe cardiovascular instability: give 3-10 mg IV (or 0.05-0.15 mg/kg in pediatrics) slowly over 3-5 minutes, followed by continuous infusion at 3-5 mg/hour (0.05-0.10 mg/kg/hour), titrated to hemodynamic response. 1, 5

• Glucagon works via non-beta-receptor pathways to restore inotropy and chronotropy. 1
• Protect the airway before glucagon administration, as vomiting is common and aspiration risk is high in obtunded patients. 1
• Plan early for adequate glucagon supply—severe cases may require >100 mg over 24 hours. 1
• Avoid concurrent dopamine, isoproterenol, or milrinone, as animal studies suggest these may reduce glucagon's effectiveness. 1

High-Dose Insulin-Euglycemia Therapy

For shock refractory to glucagon and vasopressors, administer high-dose insulin: 1 U/kg IV bolus with 0.5 g/kg dextrose, followed by continuous infusions of 0.5-1 U/kg/hour insulin and 0.5 g/kg/hour dextrose. 1, 6

• Insulin improves myocardial energy utilization and contractility independent of beta-receptors. 1
• Monitor glucose every 15 minutes initially; titrate dextrose to maintain 100-250 mg/dL (5.5-14 mmol/L). 1
• Target potassium levels of 2.5-2.8 mEq/L—avoid aggressive repletion, as animals treated with high potassium developed asystole. 1
• Concentrated dextrose solutions (>10%) require central venous access. 1
• This therapy has demonstrated survival benefit in human case reports of massive beta-blocker overdose. 1, 6

Calcium Therapy

Consider IV calcium for refractory shock: administer 0.3 mEq/kg (0.6 mL/kg of 10% calcium gluconate or 0.2 mL/kg of 10% calcium chloride) over 5-10 minutes, followed by infusion at 0.3 mEq/kg/hour. 1

• Monitor ionized calcium levels and avoid severe hypercalcemia (>2× upper limit of normal). 1
• Calcium chloride requires central venous access due to tissue injury risk with extravasation. 1

Intravenous Lipid Emulsion

For life-threatening toxicity unresponsive to conventional therapy, administer 20% lipid emulsion: 1.5 mL/kg bolus over 1 minute, followed by 0.25 mL/kg/min infusion. 2, 6

• Propranolol is highly lipophilic; lipid emulsion may act as a "lipid sink" to sequester drug from tissues. 2, 6
• Case reports demonstrate restoration of sinus rhythm and hemodynamic stability with lipid therapy when standard measures failed. 2, 6
• This is a rescue therapy for refractory cases, particularly in pediatric patients. 6

Management of Specific Complications

Bradycardia

• Treat with atropine (0.5-1 mg IV) or isoproterenol infusion. 5
• Consider temporary cardiac pacing for severe, refractory bradycardia. 5

Wide-Complex Tachycardia and Sodium Channel Blockade

• Propranolol's membrane-stabilizing effects can cause QRS widening and ventricular dysrhythmias, particularly at doses >2,000 mg. 2, 7
• Do NOT administer Class IA (quinidine, procainamide), Class IC (flecainide, propafenone), or Class III (amiodarone, sotalol) antiarrhythmics, as these exacerbate cardiac toxicity. 1
• Lipid emulsion has shown specific benefit for wide-complex tachycardia in propranolol overdose. 2

Seizures and CNS Depression

• Severe CNS depression can develop before overt cardiovascular signs, particularly with lipophilic beta-blockers like propranolol. 3
• Treat seizures with benzodiazepines; maintain airway protection and mechanical ventilation as needed. 1, 3

Bronchospasm

• Administer isoproterenol or aminophylline for beta-blocker-induced bronchospasm. 5

Monitoring and Disposition

• Continuous cardiac monitoring with serial 12-lead ECGs to detect QRS widening, QT prolongation, and dysrhythmias. 5, 7
• Monitor blood pressure, heart rate, neurobehavioral status, and urine output continuously. 5
• Early echocardiography is essential—acute dilated cardiomyopathy can develop with normal vital signs on presentation. 3
• Consider ECMO for refractory shock despite maximal medical therapy. 1
• Observe for at least 17 hours (median length of stay); severe toxicity typically occurs with ingestions ≥2,000 mg, with cardiac arrest reported at doses ≥2,400 mg. 7

Dose-Toxicity Thresholds

• Hypotension can occur with doses as low as 400 mg; bradycardia at 800 mg. 7
• Severe toxicity (seizure, coma, cardiac arrest) threshold is 2,000 mg in isolated propranolol ingestion, with 53% of patients ingesting ≥2,000 mg developing severe toxicity. 7
• Mortality is rare with aggressive supportive care, but has occurred with ingestions of 4,000-16,000 mg. 7