Obstructive & Restrictive Lung Disease

Question 1

What features to restrictive and obstructive lung diseases share?

Answer 1

• chronic
• diffuse (across the whole lung)
• non-infectious

Question 2

What are the obstructive lung diseases?

Answer 2

• asthma
• COPD
  
  • chronic bronchitis + emphysema
  • small airways disease/chronic bronchiolitis
• bronchiectasis

Question 3

What are the restrictive lung diseases?

Answer 3

• idiopathic pulmonary fibrosis
• pneumoconiosis
  
  • asbestosis
• sarcoidosis
• honeycomb lung

Question 4

What is asthma?

Answer 4

• increased responsiveness of airways to various stimuli leading to episodic bronchoconstriction which is at least partly reversible
• obstructive lung disease

Question 5

What are the two types of asthma?

Answer 5

• atopic/allergic
  
  • increased serum IgE
  • specific external allergens
• non-allergic asthma
  
  • normal serum IgE
  • non-specific triggers

Question 6

What are the phases of the asthma response?

Answer 6

• acute/immediate [tx with relievers eg ventolin/salbutamol]
  
  • increased vascular permeability –> oedema
  • increased mucous production
  • bronchospasm
• late phase (4-8 hours) [tx with corticosteroids]
  
  • chemotaxis of eosinophils, mast cells, lymphocytes, macrophages –> ongiong inflammation
  • epithelila damage

Question 7

What are the complications of asthma?

Answer 7

• short term:
  
  • death
  • atelectasis (collapse or rupture of lungs)
  • spontaneous pneumothorax and/or pneumomediastinum (rare)
• long term (severe chronic)
  
  • remodelling: fibrosis and scarring = irreversible obstruction
  • chronic hypoxia –> pulmonary hypertension –> cor pulmonale

Question 8

What is emphysema?

Answer 8

• abnormal, permanent enlargement of air spaces distal to the terminal bronchiole
• from destruction of the alveolar walls without fibrosis

Question 9

What are the types of emphysema?

Answer 9

• centriacinar (centrilobular) – from smoking
• panacinar (panlobular)
• distal acinar (paraseptal)
• irregular

Question 10

How does cigarette smoking cause emphysema?

Answer 10

• damages intralveolar septae
• attracts inflammatory cells into lung tissue
• neutrophils release a protease called elastase
• the body normally has anti-protease to downregulate proteases
  
  • smoking impairs this function
• tf getting upregulation of elastase and downregulation of its inhibition
• can develop without smoking due to an inherited form of trypsin deficiency that produces non-functional anti-proteases

Question 11

How does emphysema cause airway obstruction?

Answer 11

• loss of elastic recoil
  
  • loss of supporting elastic tissue around small airways leads to collapse
  • dynamic airway collapse during forced expiration
  • tf air moves out more slowly
• associated conditions:
  
  • small airways disease
  • chronic bronchitis

Question 12

What are the complications of emphysema?

Answer 12

• hypoxia
  
  • caused by airflow obstruction, loss of diffusion capacity due to IAV septum damage (late)
• pulmonary hypertension –> cor pulmonale
• pneumothorax

Question 13

What is chronic bronchitis?

Answer 13

• **clinical **definition:
  
  • persistent cough productive of sputum for at least 3 months in 2 consecutive years

Question 14

What is the patgogenesis of chronic bronchitis?

Answer 14

• chronic irritation by inhaled substances
  
  • cigarette smoke (rarely other things like grain dust, silica, etc.)
• increased mucous production in larger airways
  
  • due to hypertrophy of mucous secreting glands and increase in goblet cells on the surface epithelium
    
    • thickening of wall + more mucous; hypertrophy is single main contributor to the pathogenesis of chronic bronchitis
• inflammation, scarring, and narrowing of smaller airways

Question 15

What are the morphological features of chronic bronchitis?

Answer 15

• excessive mucous
  
  • due to hypertrophy of mucous secreting glands
    
    • single main contributor to pathogenesis of CB
  • increased goblet cells on the surface epithelium
• mild increase in inflammatory cells: lymphocytes, macrophages, and plasma cells, causing edema
• peribronchial fibrosis in small airways
• +/- sqamous metaplasia
  
  • predisposes to squamous cell carcinoma (lung cancer)

Question 16

What are the complications of chronic bronchitis?

Answer 16

• prone to bacterial infections
  
  • number one cause of hospital admittance
• hypoxia –> pulmonary hypertension –> cor pulmonale
• squamous metaplasia –> dysplasia –> premalignancy

Question 17

What is small airways disease?

Answer 17

• chronic inflammation, fibrosis, and obstruction of the terminal bronchioles (<2mm)
• caused by cigarette smoke
• important component of COPD

Question 18

What is COPD?

Answer 18

• emphysema, chronic bronchitis, and small airways disease
  
  • • some reversible bronchospasm/asthma in varying proportions
• slow progression with superimposed infective exacerbations
  
  • more prone to bacterial infections
• >90% caused by cigarette smoking

Question 19

Patients with predominantly chronic bronchitis present with COPD as

Answer 19

blue bloaters

bluish colour of skin and lips due to hypoxia + ankle swelling

Question 20

Patients with predominant emphysema present with COPD as

Answer 20

pink puffers

pink complexion, fast respiratory rate, pursed lips, hyperinflated lungs

Question 21

How does smoking predispose to pulmonary infection?

Answer 21

• inhibition of the muco-ciliary escalator
• increased mucous
• inhibition of leukocyte function
• direct damage to the epithelial layer

Question 22

What is bronchiectasis?

Answer 22

• Irreversible, abnormal dilation of bronchi/bronchioles

Question 23

What is the pathogenesis of bronchiectasis?

Answer 23

• severe destructive inflammation of the airways
  
  • severe or recurrent infection +/- obstruction
• loss of surrounding elastic tissue and muscle exceeds contraction of fibrous tissue
• clearance of organisms and fluid impaired
• severe infection develops, causes damage to the bronchiolar wall causing it to dilate
• dilated airways often full of pus
  
  • causes lots of foul smelling sputum
  • fever
  • SOB, cyanosis, cor pulmonale

Question 24

What causes bronchiectasis?

Answer 24

• necrotising infections
  
  • s. aureus, influenza, aspergillus
• obstruction (+infection)
  CF
• cilia disorders
• non-infections inflammatory conditions
  
  • CT diseases
  • graft-vs-host diesease
  • allergic bronchopulmonary aspergillosis

Question 25

What is restrictive (interstitial) lung disease?

Answer 25

group of conditons that share these features: * chronic, diffuse, non-infectious * restrictive spirometry * **inflammation and fibrosis of the interalveolar septa (interstitium)** * diffuse reticulonodular and/or ground glass patterns on CXR

Question 26

What is the most common form of restrictive (interstitial) lung disease?

Answer 26

* idiopathic pulmonary fibrosis/usual intersitial pneumonitis * interstitial inflammation, fibrosis at varying stages of development * inevitable progression to end-stage lung disease (~3yrs survival) * unknown cause