Pulmonary System
The pulmonary domain tests obstructive lung disease, pneumonia, pulmonary embolism, pleural disease, sleep apnea, and interstitial lung disease, emphasizing spirometry interpretation and severity-based treatment.
Core rules
- Asthma is variable airflow obstruction with symptoms and reversible FEV1 improvement after a bronchodilator. Mild asthma uses as-needed low-dose inhaled corticosteroid-formoterol rather than a short-acting beta agonist alone.
- COPD requires post-bronchodilator FEV1/FVC below 0.70. Smoking cessation and vaccination are foundational. Maintenance bronchodilators are LABA plus LAMA; add inhaled corticosteroid for frequent exacerbations or eosinophilic inflammation.
- Community-acquired pneumonia: use CURB-65 (confusion, urea, respiratory rate, blood pressure, age ≥65) to decide site of care. Start empiric antibiotics promptly.
- Pulmonary embolism: use pretest probability. Low probability with a negative D-dimer can exclude PE; high probability warrants CT pulmonary angiography and anticoagulation.
Worked example
A 24-year-old with episodic wheeze after exercise has an FEV1 that improves 15% and 250 mL after albuterol. This confirms reversible obstruction and supports asthma. She has infrequent symptoms, so start as-needed low-dose ICS-formoterol and provide an action plan. A normal chest radiograph does not exclude asthma.
Traps
- Treating asthma with a short-acting beta agonist alone and no anti-inflammatory therapy.
- Missing PE when tachycardia and hypoxemia accompany pleuritic pain.
- Overlooking obstructive sleep apnea in resistant hypertension or daytime somnolence.
- Using antibiotics for an asthma exacerbation without bacterial features.