Chronic Obstructive Pulmonary Disease

Question 1

How common is it?

Answer 1

10-20% of over 40s. 2.5x10^6 deaths/yr worldwide.

Question 2

Who does it affect?

Answer 2

Old people, heavy smokers.

Question 3

What causes it?

Answer 3

• Progressive disorder characterized by airway obstruction with no reversibility. Includes chronic bronchitis and emphysema.
• Chronic bronchitis = defined clinically as cough, sputum production on most days for 3 months of 2 successive years. Symptoms improve if they stop smoking.
• Emphysema = defined histologically as enlarged air spaces distal to terminal bronchioles, with destruction of alveolar walls.

Question 4

What risk factors are there (and how can they be reduced)?

Answer 4

• Smoking
• Pollution
• Occupational dusts and chemicals
• Frequent lower respiratory tract infections as a child.

Question 5

How does it present?

Answer 5

Differentiation from asthma – COPD favours:

• Age of onset >35yrs
• Smoking (passive or active) or pollution related
• Chronic dyspnoea
• Sputum production
• Minimal diurnal or day-to-day FEV1 variation.

Symptoms
- Cough, sputum, dyspnoea, wheeze

Signs
- Tachypnoea; use of accessory muscles of respiration; hyperinflation; reduced circosternal distance (↓3cm); ↓expansion; resonant or hyperresonant percussion note; quiet breath sounds; wheeze; cyanosis; cor pulmonale.

Pink puffers and blue bloaters

• Pink puffers – have increased alveolar ventilation, a near normal PaO2 and a normal or low PaCO2. They are breathless but not cyanosed, may progress to type 1 respiratory failure.
• Blue bloaters – have reduced alveolar ventilation, with a low PaO2 and a high PaCO2. They are cyanosed but not breathless and may go on to develop cor pulmonale. Their respiratory centres are relatively insensitive to CO2 and they rely on hypoxic drive to maintain respiratory effort (supplemental O2 should be given with care).

Complications
- Acute exacerbations (sometimes with infection); polycythaemia; respiratory failure; cor pulmonale (RHF – chronic airway damage → loss of pulmonary capillary beds → ↑resistance in lung vasculature); pneumothorax (ruptured bullae); lung carcinoma.

Question 6

Which other conditions may present similarly?

Answer 6

CHF, bronchiectasis, bronchiolitis obliterans, chronic asthma, alpha-1-antitrypsin deficiency, bronchitis, emphysema, nicotine addiction, PE.

Question 7

How would you investigate the patient?

Answer 7

• FBC: PVC↑.
• CXR: hyperinflation (>6 anterior ribs seen above diaphragm in mid-clavicular line), flat hemidiaphragms, large central pulmonary arteries, ↓peripheral vascular markings, bullae.
• ECG: right atrial and ventricular hypertrophy (cor pulmonale).
• ABG: reduced PaO2 ± hypercapnia.
• Lung function: obstructive and air trapping (FEV1 <70%. TLC↑, RV↑, DLCO↑ in emphysema).

Question 8

What treatment/s would you consider? What risks and benefits of treatment are there?

Answer 8

• Offer smoking cessation advice with cordial vigour.
• BMI often low – diet advice ± supplementation.
• Mucolytics may help productive cough.
• Depression often associated – screen for this.
• Flu and pneumococcal vaccinations.