Role of Adrenaline Nebulization in Acute Asthma Treatment
Adrenaline (epinephrine) nebulization has no established role in acute asthma treatment and should not be used—inhaled selective β2-agonists (albuterol/salbutamol) are the standard of care for bronchodilation. 1
Why Adrenaline Nebulization Is Not Recommended
Lack of Evidence for Nebulized Route
- The major asthma management guidelines do not recommend nebulized epinephrine for acute asthma treatment 1
- No evidence demonstrates that nebulized epinephrine provides any advantage over selective inhaled β2-agonists (albuterol/salbutamol) for bronchodilation 1
- The European Respiratory Society guidelines for nebulizer use in acute asthma make no mention of epinephrine as a nebulized therapy option 1
Subcutaneous Epinephrine: Limited Role Only
- Subcutaneous epinephrine (0.01 mg/kg, divided into 3 doses of approximately 0.3 mg at 20-minute intervals) can be used in acute severe asthma, but there is no evidence that subcutaneous epinephrine has advantages over inhaled β2-agonists 1
- The nonselective adrenergic properties of epinephrine cause increased heart rate, myocardial irritability, and increased oxygen demand—making it less safe than selective β2-agonists 1
- Subcutaneous epinephrine is well-tolerated even in patients >35 years of age, but this does not justify its use over safer alternatives 1
Intravenous Epinephrine: Significant Risk Without Benefit
- IV epinephrine (0.25-1 mcg/min continuous infusion) has been used in severe asthma, but one retrospective study showed a 4% incidence of serious side effects 1
- There is no evidence of improved outcomes with IV epinephrine compared with selective inhaled β-agonists 1
- A case report documented that epinephrine precipitated cardiogenic shock in a patient with unrecognized left ventricular dysfunction presenting with dyspnea, demonstrating the potential for catastrophic harm 2
What Should Be Used Instead
First-Line Bronchodilator Therapy
- Nebulized albuterol/salbutamol 2.5-5 mg (or 0.15 mg/kg in children) via oxygen-driven nebulizer every 15-30 minutes is the standard first-line treatment 1, 3, 4
- For severe exacerbations, add ipratropium bromide 500 mcg to the nebulizer (250 mcg in children), which produces clinically modest but meaningful improvement in lung function 1, 4
- Continuous nebulized albuterol is more effective than intermittent dosing in patients with severe exacerbations 1
Alternative Delivery Methods
- Metered-dose inhalers with spacers are equally effective as nebulizers in acute severe asthma and should be considered as an alternative 3, 5
- Approximately 1/6 the nebulizer dose of albuterol is needed via metered-dose inhaler to achieve similar bronchodilation 5
Driving Gas Selection
- Use oxygen at 6-8 L/min as the driving gas for nebulization in acute severe asthma to simultaneously address bronchospasm and hypoxemia 6, 3, 4
- Exception: Use compressed air instead in patients with documented CO2 retention and acidosis to avoid worsening hypercapnia 3
Critical Pitfall to Avoid
Do not use epinephrine (by any route) when cardiac dysfunction or ischemic heart disease may be present—the vasoconstrictor effects can precipitate hemodynamic collapse in patients with left ventricular dysfunction who present with dyspnea mimicking asthma 2. The case literature demonstrates that epinephrine's potent vasoconstrictor properties can worsen cardiac output and precipitate cardiogenic shock in this setting 2.
When Standard Therapy Fails
If patients do not respond to high-dose nebulized β2-agonists plus ipratropium:
- Add IV magnesium sulfate 2 g over 20 minutes, which moderately improves pulmonary function and reduces hospital admissions in severe exacerbations 1
- Administer systemic corticosteroids early (methylprednisolone 125 mg IV or prednisolone 2 mg/kg/day orally in children), as these are the only proven treatment for the inflammatory component 1, 4
- Consider aminophylline infusion (5 mg/kg IV loading dose over 20 minutes, then 1 mg/kg/hour maintenance) for non-responders 4