COPD (including chronic bronchitis & emphysema)

Question 1

Define chronic obstructive pulmonary disease (COPD)

Answer 1

COPD is an obstructive lung disease (FEV1<80% predicted, FEV1/FVC<0.7) that is poorly reversible

Includes chronic bronchitis & emphysema

Question 2

What is the pathophysiology of COPD?

Define chronic bronchitis & emphysema and their pathophysiologies

Answer 2

Significant & chronic inlammatory responce to inhaled irritants.

Chronic bronchitis;

• Defined clinically as cough & sputum production on most days for 3 months of 2 successive yrs
• Ariway narrowing (hence airflow limitation)
• Causes;
  
  • Cigarette smoke etc → Hypertrophy & hyperplasia of mucus secreting glands of the bronchial tree
  • Bronchial wall inflammation
  • Mucosal oedema
  • Epithelial cell layer may ulcerate and heal with squamous metaplasia (squamous replacing columnar epitheliam)

Emphysema;

• Defined histologically; enlarged air spaces distal to terminal bronchioles with destruction of alveolar walls
• Loss of elastic recoil (which normally keeps airway open during expansion) causing air trapping
• Causes;
  
  • ​Cigarette smoke etc → inc neutrophiles, macrophages, lymphocytes → release inflam. mediators (elastases, proteases, IL1, IL8 & TNFa)
    
    • Induce structural changes & break down connective tissue (protease-antiprotease inbalance) → Emphysema
    • → attract inflam. cell → Amplify

Question 3

What are some causes of COPD?

Answer 3

• Tobacco smoke
• Indoor (biomass fuel) & outdoor air pollution
• Occupational dusts & chemicals
• a1-antitrypsin deficiency

Question 4

What are the symptoms & signs of COPD?

Answer 4

Symptoms;

• Cough & sputum
• Dyspnoea & wheeze

Signs;

• Low - expansion, cricosternal distance, breath sounds (over bullae)
• High - hyperinflation, hyperresonant, breathing rate (tachypnoea)
• Use of accessory muscles of respiration
• Wheeze
• Cyanosis
• Cor pulmonale

Question 5

What are pink puffers & blue bloaters?

Answer 5

Pink buffers;

• Inc alveolar ventilation
• Near normal PaO2
• Normal or low PaCO2
• Breathless but not cyanosed
• May progress to type 1 resp failure
• Predominant emphysema

Blue bloaters;

• Dec alveolar ventilation
• Low Pa02
• High PaCO2
• Cyanosed but not breathless (as their resp centres are insensitive to CO2 and they rely on hypoxic drive)
• May develop cor pulmonale
• Predominant chronic bronchitis

Question 6

What are complications of COPD?

Answer 6

• Acute exacerbations +/- infection
• Polycythaemia
• Resp failure
• Cor pulmonale (oedema, inc JVP)
• Pneumothorax (ruptured bullae)
• Lung carcinoma

Question 7

How would you investigate suspected COPD and an exacerbation?

Whats used for diagnosis?

Answer 7

• Lung function; obstructive + air trapping
  
  • Diagnostic
  • FEV1 <80% predicted
  • FEV1:FVC ratio <70%
  • Inc TLC & RV (total lung capacity & residual volume)
  • Red DLCO in emphysema (carbon monoxide diffusing capacity)
• CXR
  
  • Hyperinflation (>6 ant. ribs seen above diaphragn in mid clavicular line)
  • Flat hemidiahragms
  • Large central pulmonary arteries
  • Low peripheral vascular markings
  • Bullae
• ECG
  
  • ​Right H hypertropy (cor pulmonale)
• ABG
  
  • Low PaO2 +/- hyper/pocapnia
• CRP
• FBC
  
  • ​Raised PCV (polycythaemia, raised haematocrit, % RBC in blood)

LFT
FBC
CXR
CRP
ECG
​ABG

• Sputum
• U&E

Question 8

How do you treat COPD?

Answer 8

C.O.P.D-abct

• Ciggarette cessation. exercise etc
• O2 (long term oxygen therapy) 3
• PFTs (assess) & Pneumococcal polysaccharide vaccine & Pulmonary rehab
• Drugs (ABCT)
  
  • Anticholinergic (eg ipratropium) 1
  • B2 agonist (salbutamol salmetrol) 1
  • Corticosteroid (beclametasone) 2
  • Theophyline 2

1. Mild - FEV1 50-80% predicted
2. Moderate - FEV1 30-49% predicted
3. Severe - FEV1 <30% predicted