Pulmonology · USMLE Step 1 and Step 2

COPD - Chronic Bronchitis song

Chronic Bronchitis - Pathophysiology & Findings, as a song. Hear the short teaser here. The full song is on YouTube and Spotify.

COPD - Chronic Bronchitis

Full song on YouTube ↗Spotify ↗

Key points in this song10

Chronic bronchitis is defined as a productive cough lasting at least 3 months per year for 2 or more consecutive years, caused by mucus hypersecretion from hypertrophied submucosal glands.
The Reid index, the ratio of mucous gland thickness to total bronchial wall thickness, is greater than 0.4 in chronic bronchitis (normal ≤ 0.4).
Cigarette smoking is the number one risk factor; it impairs mucociliary clearance and triggers goblet cell hyperplasia in the bronchial epithelium.
Patients are classically described as "Blue Bloaters" – cyanotic and overweight, with hypoxemia, hypercapnia, and secondary polycythemia from chronic low V/Q mismatch.
Hypoxic vasoconstriction from chronic V/Q mismatch leads to pulmonary hypertension, right ventricular hypertrophy, and ultimately cor pulmonale with peripheral edema.
PFTs show an obstructive pattern: decreased FEV1/FVC ratio (<0.70), decreased FEV1, normal or increased TLC, and increased RV due to air trapping.
The central chemoreceptor response to CO2 may be blunted chronically; these patients may rely on hypoxic drive, making high-flow oxygen administration potentially dangerous.
Acute exacerbations are most commonly triggered by Haemophilus influenzae, Streptococcus pneumoniae, or Moraxella catarrhalis, and are treated with antibiotics, bronchodilators, and systemic corticosteroids.
Long-acting bronchodilators (LABAs and LAMAs) are the mainstay of maintenance therapy; roflumilast, a PDE-4 inhibitor, reduces exacerbation frequency in severe chronic bronchitis.
The only interventions proven to reduce mortality in COPD are smoking cessation and supplemental oxygen therapy in patients with resting PaO2 ≤ 55 mmHg or SaO2 ≤ 88%.