Chronic Obstructive Pulmonary Disease (COPD)

Definition and Pathophysiology

COPD: Chronic Obstructive Pulmonary Disease, characterized by persistent and irreversible limitation of airflow through the lungs.
**Normal Breathing:
- Inspiration:** Diaphragm and intercostal muscles contract -> Increase in lung volume -> Decrease in pressure -> Air drawn in.
- Expiration: Diaphragm and intercostal muscles relax -> Decrease in lung volume -> Increase in pressure -> Air pushed out.
Mechanisms in COPD:
1. Loss of Elastic Recoil
2. Narrowing of Airways
Inflammation: Major driver, often due to inhaled toxins (e.g., cigarette smoking).
- Proteases vs. Anti-Proteases: Chronic inflammation -> Excess protease activity -> Lung tissue destruction -> Less alveolar support -> Emphysema.
- Other Effects: Increased oxygen free radicals, mucosal edema, mucus hypersecretion, bronchoconstriction, airway narrowing, fibrosis.
Increased Work of Breathing: Leads to hypoxia (low oxygen) and hypercapnia (high carbon dioxide).

Primary Cause: Cigarette smoking (up to 70% of cases).
Other Causes: Pollution, mineral dust, chemicals, genetic factors (e.g., Alpha-1 antitrypsin deficiency).

Dyspnea: Persistent and worsening shortness of breath, initially with exercise, later at rest.
Cough: Can be productive or non-productive.
- Chronic Bronchitis: Cough for >3 months in 2 consecutive years.
Other Symptoms: Recurrent wheezing, respiratory infections, fatigue, weight loss, chest tightness.
Phenotypes:
- Blue Bloaters: Chronic bronchitis features (productive cough, dyspnea, obesity, cyanosis).
- Pink Puffers: Emphysema features (thin body habitus, pursed lip breathing).

Spirometry: Demonstrates irreversible obstructive pattern.
- FEV1/FVC ratio < 0.7, FEV1 indicates severity of obstruction.
COPD Assessment Test (CAT): Measures symptom severity.
Additional Tests: Pulse oximetry, ABG, full blood count, chest x-ray, genetic testing (select cases).

**Medications:
- Short-Acting Beta Agonists (SABA):** e.g., Salbutamol.
- Short-Acting Muscarinic Antagonists (SAMA): e.g., Ipatropium bromide.
Oxygen Therapy: Target saturations 88-92%.
Systemic Steroids: e.g., Prednisolone, Hydrocortisone.
Antibiotics: If infection suspected.
Ventilation: Non-invasive ventilation for type 2 respiratory failure.

Goals: Reduce symptoms, exacerbations, and mortality.
Smoking Cessation: Primary measure.
Pulmonary Rehabilitation: Aerobic exercise, strength training, education.
Vaccinations: Flu, pneumococcal, COVID.
Pharmacological Management:
- Bronchodilators: Beta agonists (e.g., Salbutamol), Muscarinic antagonists (e.g., Ipratropium).
- Inhaled Corticosteroids: Based on eosinophil count and history of exacerbations.
Long-Term Oxygen Therapy: Based on PaO2 levels.
Advanced Options: Bulectomy, volume reduction surgery, transplant.