Pulmonary Disease Processes

COPD is an obstructive lung disease with persistent, not fully reversible airflow limitation, predominantly caused by tobacco smoke (90% of cases). Encompasses emphysema and chronic bronchitis.

Emphysema: destruction of alveolar walls → loss of elastic recoil → air trapping. 'Pink puffer' (Type A COPD): thin, tachypneic, pursed-lip breathing, barrel chest, minimal hypoxemia until advanced.

Chronic bronchitis: productive cough ≥3 months/year for ≥2 consecutive years. Mucus hypersecretion, airway inflammation. 'Blue bloater' (Type B COPD): hypoxic, hypercapnic, polycythemic, edematous, frequent exacerbations.

Diagnosis requires a post-bronchodilator FEV1/FVC <0.70. GOLD then grades airflow limitation by post-bronchodilator FEV1 % predicted: GOLD 1 (mild ≥80%), GOLD 2 (moderate 50–79%), GOLD 3 (severe 30–49%), GOLD 4 (very severe <30%).

Since GOLD 2023, treatment is guided by a separate ABE assessment of symptoms and exacerbation history: Group A — 0–1 moderate exacerbations (none leading to hospitalization) and few symptoms (mMRC 0–1, CAT <10); Group B — the same exacerbation history with more symptoms (mMRC ≥2, CAT ≥10); Group E — ≥2 moderate exacerbations or ≥1 leading to hospitalization in the past year, whatever the symptoms. The grade (1–4) and group (A, B, E) are reported together, e.g. GOLD 3, Group E.

Asthma is reversible airway hyperresponsiveness and inflammation with intermittent episodes of bronchospasm.

NAEPP (EPR-3) severity categories: intermittent (symptoms ≤2 days/week, ≤2 nighttime awakenings/month, FEV1 ≥80%), mild persistent (>2 days/week, 3–4 nights/month), moderate persistent (daily symptoms, >1 night/week), severe persistent (symptoms throughout the day, often nightly).

GINA (2019 onward) no longer recommends SABA-only treatment for adults and adolescents: every patient should receive ICS-containing therapy. Track 1 (preferred) uses low-dose ICS-formoterol as the reliever. Steps 1–2: as-needed low-dose ICS-formoterol. Step 3: low-dose maintenance-and-reliever ICS-formoterol (MART). Step 4: medium-dose MART. Step 5: add-on LAMA, phenotype assessment, consider biologics. Track 2 (alternative) uses a SABA reliever, but always with ICS: Step 1 takes ICS whenever the SABA is taken; Step 2 daily low-dose ICS; Steps 3–4 ICS-LABA; Step 5 add-on therapy.

Status asthmaticus: severe acute asthma not responding to initial treatment — risk of respiratory arrest. Management: aggressive bronchodilators, IV magnesium, possible intubation (avoid if possible — very difficult to ventilate).

Pulmonary embolism (PE) is a thrombus obstructing the pulmonary arterial circulation. PE is on the differential for any unexplained tachycardia, hypoxemia, or pleuritic chest pain.

Risk factors (Virchow's triad): venous stasis (prolonged immobility, surgery), endothelial injury, hypercoagulability (malignancy, genetic thrombophilia, OCP).

Classification: massive PE (hemodynamic instability, SBP <90 or 40 mmHg drop) → systemic thrombolytics or catheter-directed therapy; submassive PE (RV dysfunction but hemostable) → anticoagulation ± catheter therapy; low-risk PE → anticoagulation.

Respiratory findings: tachypnea, pleuritic chest pain, hemoptysis, sudden-onset dyspnea. ABG: respiratory alkalosis + elevated A-a gradient. ECG: S1Q3T3, sinus tachycardia.