Obstructive Spirometry
FEV1 / FVC ratio < 0.70 (reversible in asthma; fixed in COPD)
COPD Mortality Reducers
Smoking cessation & Supplemental O2 (> 15 hrs/day if PaO2 ≤ 55 mmHg)
Exacerbation Triad
Increased dyspnea, increased sputum volume, increased sputum purulence → Antibiotics
BiPAP Indications
pH < 7.35 and PaCO2 > 45 mmHg in acute COPD exacerbation
Asthma vs. COPD Comparative Spirometry & Pathology
Differentiating the two primary obstructive lung diseases on board examinations:
| Feature | Asthma | Chronic Obstructive Pulmonary Disease (COPD) |
|---|---|---|
| Onset & Age | Childhood / adolescence (atopic history) | Adults > 40 years with > 20 pack-year smoking history |
| Airflow Reversibility | Reversible (> 12% and > 200 mL increase in FEV1 post-bronchodilator) | Largely irreversible / fixed obstruction (post-bronchodilator FEV1/FVC < 0.70) |
| Primary Airway Inflammatory Cell | Eosinophils, CD4+ T-helper 2 cells, IgE / mast cells | Neutrophils, CD8+ cytotoxic T cells, alveolar macrophages |
| Diffusing Capacity (DLCO) | Normal or elevated | Decreased in emphysema (destruction of alveolar-capillary bed) |
| First-Line Controller | Inhaled Corticosteroid (ICS) + Formoterol (SMART therapy) | Long-Acting Muscarinic Antagonist (LAMA) (Tiotropium) + LABA |
Acute COPD Exacerbation Inpatient Management
Hospital management follows a standardized, evidence-based ladder:
1. Bronchodilators
Inhaled Short-Acting Beta-2 Agonist (Albuterol) plus Short-Acting Muscarinic Antagonist (Ipratropium) every 1–4 hours via nebulizer.
2. Systemic Corticosteroids
Oral Prednisone 40 mg daily for 5 days (improves FEV1, shortens hospital recovery, reduces relapse).
3. Antibiotics (The Cardinal Symptoms)
Indicated if patient has purulent sputum plus either increased dyspnea or volume (or if mechanically ventilated). Target: Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis. First line: Azithromycin, Doxycycline, or Augmentin for 5–7 days.
4. Non-Invasive Positive Pressure Ventilation (NIPPV / BiPAP)
First-line ventilator support for respiratory acidosis (pH < 7.35, PaCO2 > 45 mmHg). Significantly reduces intubation rates and mortality.
COMLEX / OMM Integration
NBOME High-Yield Correlate
Respiratory Somatic Dysfunctions & Treatment Order
- Autonomics: Pulmonary sympathetics arise from
- Diaphragm Doming & Rib Raising: Chronic air trapping flattens the respiratory diaphragm. Doming the diaphragm and mobilizing the lower ribcage (ribs 6–10) restores normal negative intrathoracic pressure swings and improves venous return.
T2–T7. Parasympathetics from Vagus (CN X).- Diaphragm Doming & Rib Raising: Chronic air trapping flattens the respiratory diaphragm. Doming the diaphragm and mobilizing the lower ribcage (ribs 6–10) restores normal negative intrathoracic pressure swings and improves venous return.
Board Traps & Common Distractors
- Trap: Over-oxygenating a chronic COPD patient. Titrate FiO2 to a target SaO2 of 88% to 92%. Over-oxygenation abolishes hypoxic vasoconstriction in poorly ventilated alveoli (worsening V/Q mismatch) and causes the Haldane effect, triggering acute CO2 narcosis and coma.
- Trap: Ordering long-acting beta-agonists (LABA) as monotherapy in asthma. LABA without an inhaled corticosteroid increases asthma-related mortality!