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Stem
A 66-year-old man with a 50 pack-year smoking history and known severe COPD (FEV1 35% predicted) presents to the outpatient clinic with six months of progressive ankle swelling, increasing dyspnoea (now on minimal exertion), and a 5 kg weight gain. He snores loudly and admits to daytime somnolence. On examination: cyanosed, JVP raised to the angle of the jaw at 45 degrees with prominent v waves, a parasternal heave, a loud palpable P2, a pansystolic murmur at the lower left sternal edge louder in inspiration, hepatomegaly (4 cm) with bilateral pitting ankle oedema to the mid-shin. SpO2 88% on room air. Chest: barrel-shaped, prolonged expiration, biphasic wheeze, coarse crackles at both bases. ABG (room air): pH 7.36, PaO2 52 mmHg (6.9 kPa), PaCO2 58 mmHg (7.7 kPa), HCO3 32 mmol/L.
Questions
a) What is the diagnosis, and what specific underlying complications are present? (2 marks)
b) Outline the pathophysiological mechanism linking his COPD to the right-heart findings. (3 marks)
c) List the key investigations you would order and what each would show. (2 marks)
d) Describe the definitive, stepwise management with drug names, doses, routes and rationale. (3 marks)
Model answers
a) Chronic cor pulmonale from COPD (Group 3 pulmonary hypertension) — right ventricular hypertrophy and failure secondary to pulmonary hypertension caused by lung disease. Underlying complications present: chronic hypoxaemia (PaO2 under 55 mmHg) with compensated type 2 respiratory failure (raised HCO3 from chronic CO2 retention), and clinical features of right-heart failure (raised JVP with prominent v waves = tricuspid regurgitation, parasternal heave = RV hypertrophy, loud P2 = pulmonary hypertension, hepatomegaly and ankle oedema = systemic venous congestion). Probable coexistent obstructive sleep apnoea (overlap syndrome) given the loud snoring and daytime somnolence.
b) Two convergent mechanisms raise pulmonary vascular resistance (PVR): (1) HYPOXIC PULMONARY VASOCONSTRICTION (Euler-Liljestrand reflex) — chronic alveolar hypoxia inhibits KV channels on pulmonary arterial smooth muscle, causing depolarisation, calcium influx and vasoconstriction; (2) LOSS OF THE PULMONARY VASCULAR BED — emphysematous destruction of alveolar-capillary units reduces the cross-sectional area of the pulmonary circulation. Secondary remodelling (medial hypertrophy, intimal fibrosis) fixes the raised PVR. The raised PVR chronically loads the right ventricle: it first HYPERTROPHIES (concentric) to compensate, then DILATES and FAILS as afterload continues to rise. Tricuspid annular dilatation causes tricuspid regurgitation; systemic venous pressure rises giving JVP, hepatomegaly, ascites, oedema; cardiac output falls giving fatigue and (in severe PH) syncope. The RV is uniquely vulnerable — thin-walled, low afterload-tolerance, perfused during both systole and diastole.
c) Echocardiography (RV hypertrophy/dilatation, D-shaped septum, tricuspid regurgitation, estimated RV systolic pressure raised, TAPSE for RV function; normal LV to exclude left-heart disease). ECG (right-axis deviation, P-pulmonale, RBBB, dominant R in V1). Chest X-ray (enlarged central pulmonary arteries with peripheral pruning, RV prominence, hyperinflation, flat hemidiaphragms). High-resolution CT (emphysema distribution, exclude ILD/cancer). Arterial blood gases (confirmed type 2 respiratory failure with chronic compensation). Spirometry (confirm COPD severity). Full blood count (secondary polycythaemia from chronic hypoxia). NT-proBNP (screening marker). Polysomnography (confirm OSA/overlap syndrome). V/Q scan (exclude chronic thromboembolic PH — a potentially curable cause). Right heart catheterisation (gold standard; confirms PH, classifies pre-capillary with PCWP under 15 mmHg, measures PVR).
d) 1. TREAT THE UNDERLYING LUNG DISEASE — optimise COPD: dual bronchodilation (LAMA + LABA, e.g. tiotropium 18 microgram once daily + formoterol); add ICS only if eosinophils raised or frequent exacerbations; pulmonary rehabilitation; influenza and pneumococcal vaccination; SMOKING CESSATION (only disease-modifying intervention in COPD — nicotine replacement/varenicline/bupropion). 2. LONG-TERM OXYGEN THERAPY (LTOT) — at least 15 hours/day to raise PaO2 above 60 mmHg (over 8 kPa); IMPROVES SURVIVAL (MRC and NOTT trials) by reversing hypoxic pulmonary vasoconstriction. 3. OPTIMISE VENTILATION — NIV (BiPAP) for chronic hypercapnia; CPAP for confirmed OSA; reduces PVR and RV load. 4. CAUTIOUS DIURESIS — furosemide 20-40 mg orally, titrated, with renal function monitoring; the RV is preload-dependent — over-diuresis lowers cardiac output. 5. TREAT ATRIAL ARRHYTHMIA — rate-control + anticoagulation if AF/flutter. 6. AVOID routine pulmonary vasodilators in COPD-related PH (worsen V/Q mismatch); consider only under a specialist PH centre. 7. EXCLUDE CTEPH with a V/Q scan in every case — pulmonary endarterectomy is potentially curative.