Asthma vs. COPD: Understanding the Difference
Asthma and chronic obstructive pulmonary disease (COPD) are both obstructive airway diseases that cause wheezing, dyspnea, and cough. However, they differ in important ways that affect management. Asthma is a reversible airway disease characterized by bronchospasm, airway inflammation, and mucus production, typically triggered by allergens, exercise, cold air, or respiratory infections. COPD is a progressive, largely irreversible disease (comprising chronic bronchitis and emphysema) caused primarily by smoking, with gradual destruction of lung tissue and chronic airway inflammation.
In the field, the distinction matters most when considering oxygen therapy. Most asthma patients can receive high-flow oxygen without concern. Some COPD patients with chronic CO2 retention rely on hypoxic drive for their respiratory stimulus, and high-flow oxygen may theoretically diminish their drive to breathe. However, never withhold oxygen from a hypoxic patient regardless of their history. Hypoxia kills faster than hypercapnia. Current evidence supports titrating oxygen to a target SpO2 of 88 to 92% for known COPD patients while closely monitoring respiratory effort.
Acute Asthma Management
An acute asthma exacerbation presents with wheezing (may be absent in severe attacks due to minimal air movement), dyspnea, tachypnea, tachycardia, and accessory muscle use. Patients often assume the tripod position and speak in short phrases or single words. Assess severity using the ability to speak (sentences = mild, phrases = moderate, words = severe, unable to speak = critical).
Prehospital treatment follows a stepwise approach:
- Oxygen: Administer supplemental oxygen to maintain SpO2 above 94%.
- Bronchodilator: Albuterol via nebulizer (2.5 mg in 3 mL saline) or metered-dose inhaler (4 to 8 puffs with spacer). Albuterol is a beta-2 agonist that relaxes bronchial smooth muscle, relieving bronchospasm. Repeat every 5 to 15 minutes as needed for persistent symptoms.
- Ipratropium: Often combined with albuterol (DuoNeb) for moderate to severe exacerbations. Ipratropium is an anticholinergic that provides additional bronchodilation through a different mechanism.
- Epinephrine: For severe asthma not responding to nebulized bronchodilators, IM epinephrine (0.3 mg of 1:1,000) may be administered per protocol.
- CPAP: Continuous positive airway pressure can help keep airways open and improve oxygenation in patients with severe bronchospasm who are not responding to nebulized medications.
COPD Exacerbation Management
COPD exacerbations are typically triggered by respiratory infections, air pollution, or medication noncompliance. Patients present with increased dyspnea beyond their baseline, increased cough and sputum production, and worsening exercise tolerance. The treatment approach is similar to asthma: oxygen (titrated to 88 to 92% SpO2), bronchodilators (albuterol and ipratropium), and CPAP for respiratory distress. Monitor closely for signs of respiratory failure: decreasing mental status, rising ETCO2, and worsening fatigue.
Recognizing Respiratory Failure
Both asthma and COPD can progress to respiratory failure, requiring positive pressure ventilation. Warning signs include silent chest (no air movement, and therefore no wheezing), altered mental status, bradycardia (a pre-arrest sign), cyanosis despite oxygen therapy, and decreasing respiratory effort (the "quiet patient" who was previously in severe distress). If BVM ventilation is needed, high airway resistance from bronchospasm makes ventilation challenging. Use slow, deliberate breaths and allow adequate exhalation time to prevent auto-PEEP (air trapping). Consider early advanced airway placement if BVM ventilation is ineffective.