Pulmonary Pathophysiology - Restrictive Lung Disease

Question 1

Restrictive lung disease definition

Answer 1

Diseases in which the expansion of the lung is restricted either because of alterations in the lung parenchyma, diseases of the pleura, chest wall or neuromusculature

Question 2

Lung parenchyma definition

Answer 2

Gas exchanging lung tissue

Question 3

Blood gas barrier diagram

Answer 3

Question 4

Structure of type I collagen in alveolar wall

Answer 4

Forms type 1 collagen cable to support structure

Question 5

Diffuse interstitial pulmonary fibrosis: alternate names

Answer 5

Idiopathic interstitial fibrosis
Interstitial pneumonia
Cryptogenic fibrosing alveolitis

Question 6

Pathology of diffuse interstitial pulmonary fibrosis

Answer 6

Thickening of interstitium of alveolar wall

Initial infiltration with lymphocytes and plasma cells

Later fibroblasts lay down thick collagen bundles

Alveoli may contain cellular exudate ‘desquamation’

Eventually architecture is destroyed ith extensive scarring, dilated air spaces and ‘honey-combing’

Question 7

Scarring definition

Answer 7

End result of many pathological processes
Due to laying down of collagen

Question 8

Clinical features of Diffuse Interstitial Pulmonary Fibrosis

Answer 8

Not common

SOB with rapid shallow breathing

Reduced exercise tolerance

Dry cough

Question 9

Signs of diffuse interstitial pulmonary fibrosis

Answer 9

Fine crepitations
Finger clubbing
Reduced chest movements

Question 10

Radiological features of diffuse interstitial pulmonary fibrosis

Answer 10

CXR - small lungs with reticular pattern

Honey-comb appearance in late disease / on CT scan

Question 11

Ventilatory mechanics and volume changes in restrictive lung disease

Answer 11

Low FEV1 and low FVC
Normal or increased FEV/FVC ratio

All lung volumes reduced

Reduced lung compliance

Question 12

Changes to calibre of alveoli / small airways in pulmonary fibrosis

Answer 12

Calibre increases due to radial traction forces

Therefore have higher initial flow rates

Question 13

Gas exchange changes in diffuse interstitial pulmonary fibrosis

Answer 13

Reduced PaO2
Normal or low PaCO2

PaO2 falls on exercise

Reduced diffusing capacity

Question 14

Pulmonary circulation changes in diffuse interstitial pulmonary fibrosis

Answer 14

Many capillaries are obliterated by fibrosis

Pulmonary vascular resistance increases

Pulmonary hypertension - especially on exercise

Question 15

Possible trigger for breathing with diffuse interstitial pulmonary fibrosis

Answer 15

?stimulation of J receptors causing rapid shallow breathing

Especially in context of normal or low PaCO2

Question 16

Primary cause of arterial hypoxaemia in diffuse interstitial pulmonary fibrosis

Answer 16

V/Q mismatch

Question 17

Diseases which can cause interstitial pulmonary fibrosis

Answer 17

Sarcoidosis
Hypersensitivity pneumonitis
Collagen diseases
Drugs
Oxygen toxicity
Poisons

Question 18

Features of Sarcoidosis

Answer 18

Characteristic non caseating granulomas
Affects several organs
Probable immunological basis
Can cause interstitial pulmonary fibrosis

Question 19

Features of Hypersensitivity pneumonitis

Answer 19

Disease of lung parenchyma due to hypersensitivity to inhaled organic dusts

Exposure is heavy

Acute disease causes SOB, fever and cough

Longstanding disease can cause interstitial pulmonary fibrosis

Question 20

Examples of causes of Hypersensitivity pneumonitis

Answer 20

Farmer’s lung - spores in mouldy hay

Bird breeder’s lung

Question 21

Collagen disease example

Answer 21

Systemic scleroderma

Question 22

Drugs which can cause interstitial pulmonary fibrosis

Answer 22

Bleomycin
Busulfan

Question 23

Poison example which can cause interstitial pulmonary fibrosis

Answer 23

Paraquat - a weed killer

Question 24

Causes of restrictive lung disease outside of the lung

Answer 24

Pleural diseases

Chest wall diseases

Neuromuscular diseases

Question 25

Pleural diseases which can cause restrictive lung disease

Answer 25

Pneumothorax
Pleural effusion
Pleural thickening

Question 26

Chest wall diseases which can cause restrictive lung disease

Answer 26

Scoliosis
Ankylosing spondylitis

Question 27

Neuromuscular diseases which can cause restrictive lung disease

Answer 27

Polio
Guillain-Barre syndrome
Myasthenia gravis
Muscular dystrophy