Chronic obstructive pulmonary disease

Overview

•Gold standard: post-bronchodilator spirometry - FEV1/FVC <0.7 confirms obstruction; FEV1 % predicted grades severity (GOLD 1-4)
•CXR features (highly suggestive but not diagnostic alone):
•Hyperinflation (>6 anterior ribs visible above diaphragm)
•Flattened, depressed hemidiaphragms
•Hyperlucent lung fields (reduced vascular markings)
•Narrow cardiac silhouette; bullae may be visible
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CXR findings are highly suggestive of COPD but spirometry is still required to confirm the diagnosis.

Presentation

•Typically >40 years, significant smoking history, insidious onset
•Chronic productive cough - morning predominant; mucoid sputum (purulent in exacerbation)
•Progressive exertional dyspnoea - graded by MRC dyspnoea scale (1-5)
•Barrel chest, pursed-lip breathing, use of accessory muscles, expiratory wheeze
•Cor pulmonale - raised JVP, peripheral oedema, right ventricular heave (advanced disease)

Investigations

•ABG - assess hypoxaemia and hypercapnia; essential before LTOT and in acute exacerbation
•FBC - polycythaemia (chronic hypoxaemia); exclude anaemia
•Alpha-1 antitrypsin - if age <45, non-smoker, or family history
•ECG/echo - if cor pulmonale suspected

Complications

•Cor pulmonale - right heart failure from chronic hypoxaemia-driven pulmonary hypertension
•Type 2 (hypercapnic) respiratory failure - chronic CO2 retention with compensatory metabolic alkalosis
•Secondary polycythaemia - chronic hypoxaemia → erythropoietin → hyperviscosity and thrombotic risk
•Spontaneous pneumothorax - rupture of emphysematous bullae; life-threatening with poor respiratory reserve
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High-flow O2 in COPD raises PaCO2 via the Haldane effect (CO2 displaced from haemoglobin) and V/Q mismatch worsening - not just suppression of hypoxic drive. Target SpO2 88-92% in known or suspected COPD.

Management - stable COPD

•Smoking cessation - single most effective intervention; slows FEV1 decline and reduces mortality. Offer varenicline, bupropion, or nicotine replacement therapy
•Pulmonary rehabilitation - all patients with MRC grade ≥3; reduces dyspnoea and hospital admissions
•Vaccinations - annual influenza, pneumococcal, COVID-19
•LTOT - PaO2 ≤7.3 kPa on room air (or ≤8.0 kPa with polycythaemia, pulmonary hypertension, or oedema); must use ≥15 hours/day; reduces mortality
Step 1 · All patients
  1. 1Salbutamol (SABA) or ipratropium (SAMA) - short-acting bronchodilator as needed
Step 2 · Persistent symptoms
  1. 1Tiotropium (LAMA) or salmeterol/formoterol (LABA) - long-acting bronchodilator regularly
  2. 2LABA + LAMA (e.g. umeclidinium/vilanterol) - if symptoms not controlled on monotherapy
Step 3 · Persistent exacerbations or eosinophilia
  1. 1Triple therapy: LABA + LAMA + ICS (e.g. fluticasone/umeclidinium/vilanterol)
  2. 2Roflumilast (PDE-4 inhibitor) - add-on for FEV1 <50% with chronic bronchitis and frequent exacerbations
  3. 3Azithromycin prophylaxis - check ECG (QTc risk), sputum culture, audiology before initiating
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ICS monotherapy is not recommended in COPD - ICS should only be added on top of a long-acting bronchodilator when there is a specific indication (frequent exacerbations, blood eosinophilia ≥300 cells/µL). ICS without these indications increases pneumonia risk without clear benefit.