Obstructive and Restrictive Lung Diseases

Question 1

What are obstructive lung diseases?

Answer 1

• Chronic, diffuse and non-infectious diseases

- Characterised by decreased FEV1 and altered flow-volume loop mechanics

Question 2

What are some examples of obstructive lung diseases?

Answer 2

1. Emphysema: alveolar wall destruction
2. Chronic bronchitis: productive cough and airway inflammation
3. Asthma: reversible bronchial obstruction due to hyper responsiveness
4. Small airways disease
5. Bronchiectasis

Question 3

How is an asthma attack treated?

Answer 3

1. B2-adrenoceptor agonist (salbutamol) = smooth muscle relaxation and bronchodilation
2. Corticosteroids = reduction inflammatory response (will also target late-phase response)

Question 4

What is emphysema?

Answer 4

• Abnormal, permanent enlargement of airspaces distal to the terminal bronchiole
• Due to the destruction of the alveolar wall without fibrosis
• Causes loss of elastic recoil in the lungs and small airway collapse and airway obstruction
• Causes hypoxia, pulmonary hypertension and cor pulmonale

Question 5

What are the 4 main patterns of emphysema?

Answer 5

1. Centracinar:
   - Occurs in middle of lobule (respiratory bronchiole)
   - Seen with smoking
2. Panacinar:
   - Occurs throughout entire acinus
   - Seen with genetic a1-antitryspin deficiency
3. Distal acinar:
   - Emphysema just below the lung pleura -> spontenous pneumothorax in tall, thin, young males
4. Irregular:
   - Emphysema seen next to a scar

Question 6

What is chronic bronchitis?

Answer 6

• Persistent cough productive of sputum for at least 3 months in 2 consecutive years
• Due to chronic irritation by inhaled substances
• Leads to increased mucous production (hypertrophy of mucous secreting glands <0.4), airway inflammation (lymphocytes, macrophages), scarring and narrowing

Complications:

1. Squamous metaplasia in respiratory epithelium may also occur (predisposes to squamous cell carcinoma)
2. Hypoxia, pulmonary hypertension, cor pulmonale
3. Superimposed infective exacerbations

Question 7

What is small airways disease?

Answer 7

• Chronic inflammation, fibrosis and obstruction of terminal bronchioles
• 90% caused by cigarette smoke

Question 8

What is COPD?

Answer 8

• Combination of emphysema, chronic bronchitis and small airways disease
• Characterised by slow progression with superimposed infective exacerbations (bacterial bronchitis)

Question 9

What is bronchoectasis?

Answer 9

• Irreversible, abnormal dilation of bronchi/bronchioles
• Due to severe destructive inflammation of airways (usually from necrotising infection +/- obstruction)
• Dilated airways often full of pus
• Severe cough productive of foul smelling sputum

Question 10

What are restrictive lung diseases?

Answer 10

• Chronic, diffuse, non-infectious conditions caused by inflammation and fibrosis of lung interstitium
• Increased resistive WOB
• Reduced FVC

Question 11

What are some examples of restrictive lung diseases?

Answer 11

1. Idiopathic pulmonary fibrosis
2. Pneumoconiosis (coal, silica)
3. Sarcoidosis

Question 12

What is idiopathic pulmonary fibrosis?

Answer 12

• Most common and severe restrictive lung disease

- Histological pattern in “usual interstitial pneumonitis” - combination of both early and late stage fibrosis