What is the dose of epinephrine (adrenaline) for severe asthma exacerbations?

Epinephrine Dosing for Severe Asthma Exacerbations

For severe asthma exacerbations, subcutaneous epinephrine (concentration 1:1000) should be administered at 0.01 mg/kg, divided into 3 doses of approximately 0.3 mg given at 20-minute intervals. 1

Subcutaneous Administration

• The standard adult dose is 0.3-0.5 mg subcutaneously every 20 minutes for 3 doses 1
• For children, the dose is 0.01 mg/kg up to 0.3-0.5 mg every 20 minutes for 3 doses 1
• Although epinephrine has nonselective adrenergic properties that may increase heart rate and myocardial irritability, it is generally well-tolerated even in patients over 35 years of age 1, 2

Intravenous Administration

• For severe refractory asthma, IV epinephrine may be considered at an initial dose of 0.25-1 mcg/min as a continuous infusion 1
• Caution is warranted with IV administration as one retrospective study indicated a 4% incidence of serious side effects 1
• However, a small case series of younger adults with life-threatening asthma found IV epinephrine to be safe with no significant adverse events 3

Important Considerations

• There is no evidence that subcutaneous epinephrine has advantages over inhaled β2-agonists for asthma exacerbations 1, 4
• In patients with mild to moderate asthma, inhaled epinephrine is equally effective as injected epinephrine with fewer side effects 4
• For severe airway obstruction (PEFR <25% of predicted), parenteral epinephrine may be superior to aerosol delivery 4
• Nebulized epinephrine (1 mg) has been shown to be as effective as nebulized salbutamol (2.5 mg) in acute severe asthma 5

Treatment Algorithm

1. First-line treatment: Use inhaled short-acting beta-agonists (albuterol 2.5-5 mg via nebulizer every 20 minutes for 3 doses) 6, 7
2. Add ipratropium bromide (0.5 mg via nebulizer every 20 minutes for 3 doses) for severe exacerbations 6, 7
3. Administer systemic corticosteroids early (prednisone 40-80 mg/day or equivalent) 6, 7
4. For severe refractory asthma not responding to the above:
   • Consider subcutaneous epinephrine (0.01 mg/kg, ~0.3 mg per dose) every 20 minutes for 3 doses 1
   • Consider IV magnesium sulfate (2g over 20 minutes) 1, 7
   • For life-threatening cases, consider IV epinephrine (0.25-1 mcg/min) 1, 3

Cautions and Contraindications

• Do not inject epinephrine into buttocks, digits, hands, or feet 8
• Use with caution in patients with underlying heart disease, hyperthyroidism, Parkinson's disease, diabetes, and pheochromocytoma 8
• Epinephrine may interact with cardiac glycosides, halogenated hydrocarbon anesthetics, tricyclic antidepressants, and MAO inhibitors 8
• Monitor for adverse reactions including anxiety, tremor, palpitations, and arrhythmias 8

Monitoring

• Continuously monitor oxygen saturation until a clear response to therapy has occurred 6, 7
• Reassess patients 15-30 minutes after starting treatment 7
• Response to treatment is a better predictor of hospitalization need than initial severity 7