6.5 Pathophysiology of COPD

Question 1

Define COPD

Answer 1

• Preventable, treatable
• Airflow limitation, not fully reversible
• Usually progressive

Question 2

Symptoms that are suggestive of COPD

Answer 2

• Exertional breathlessness
• Cough
• Sputum

Question 3

What history features could indicate increased risk of COPD?

Answer 3

• Smoking
• Exposure to other noxious agents

Question 4

What is the FEV1/FVC ratio range that suggests COPD? What other condition is necessary for this?

Answer 4

• FEV1/FVC <0.70
• AND: bronchodilators have been given

Question 5

What proportion of Australians over 45 have COPD?

Answer 5

1 in 20

Question 6

What cardiovascular diagnosis is often used mistakenly instead of COPD?

Answer 6

Angina; since it commonly causes breathlessness.

Question 7

List some childhood risk factors for COPD

Answer 7

• Low birth weight
• Smoking exposure
• Famine

Question 8

Is there a genetic component to COPD?

Answer 8

Yes; there is basically one for every disease

Question 9

Describe how epigenetic modification leads to inflammation in COPD

Answer 9

• Histone acetylation
• DNA is bound more loosely
• More transcription
• Production of inflammatory mediators

Question 10

Clinical features of COPD

Answer 10

• Wheeze
• Dyspnoea
• Chest tightness/fullness
• Cough (more often in mornings)
• Sputum production

Question 11

Common history signs of COPD

Answer 11

• Recurrent chest infections (often in winter)
• Tobacco
• Occupational exposure
• Hobbies

Question 12

CXR signs of COPD

Answer 12

-Lungs are bigger
- Fewer lung markings visible
- Heart is pulled down
- Diaphragm is flattened

Question 13

What does emphysema look like on a CT scan of the lungs?

Answer 13

Black holes in lungs

Question 14

Why do people with obstructive lung diseases inhale less air?

Answer 14

• More air is trapped in the lung
• Less space for new air to be inhaled

Question 15

Why are anxiety and depression common in COPD?

Answer 15

Breathlessness -> inactivity -> deconditioninng -> exercise intolerance -> disability/mortality

A vicious spiral downwards

Question 16

Common viruses that exacerbate COPD

Answer 16

• Rhinoviruses
• Influenza viruses

Question 17

Common bacteria that exacerbate COPD

Answer 17

• Haemophilus influenzaue
• Streptococcus pneumoniae

Question 18

Effect of COPD exacerbations on mortality

Answer 18

Great increase in risk, even after first exacerbation

Question 19

Four main signs of asthma in terms of pathophysiology

Answer 19

• Lung inflammation
• Airway hyper-responsiveness
• Airway remodelling
• Mucous hypersecretion

Question 20

What happens during an asthma attack?

Answer 20

• Smooth muscle constricts
• More mucous is secreted

Question 21

How does the ability of cilia to clear airways change in a person with asthma?

Answer 21

• Decreases
• Leads to more mucus lining the airways

Question 22

Describe the airway remodelling that occurs during asthma

Answer 22

• Subepithelial fibrosis
• Angiogenesis
• Smooth muscle cell hyperplasia

Question 23

Is airway remodelling more pronounced in chronic or acute asthma?

Answer 23

Chronic

Question 24

What characterises allergic asthma?

Answer 24

Raised IgE levels

Question 25

What characterises eosinophilic asthma?

Answer 25

Raised eosinophil count; greater than

Question 26

What is type 2 inflammation?

Answer 26

Inflammation mediated by Th 2 cells

Question 27

What type of asthma involves type 1 inflammation?

Answer 27

non-eosinophilic, non-allergic asthma

Question 28

Describe early phase asthma response

Answer 28

- Typical asthma attack - Inhaled allergen -> mast cell degranulation - Reaction occurs within 10-15mins

Question 29

Describe late phase asthma reactions

Answer 29

- Occurs 3-4 hours after initial exposure - Involves T cells, eosinophils, and neutrophils - Can have non-specific increased bronchial reactivity for up to 2 weeks

Question 30

What are two of the most common types of COPD?

Answer 30

- Chronic bronchitis - Emphysema

Question 31

Describe emphysema

Answer 31

- Loss of elasticity - Hyperinflation of lungs - Increased airspaces (instead of many small ones), decreased SA:V

Question 32

Describe COPD Pathophysiology. How does this link to exacerbation?

Answer 32

- Inhaled irritant/toxin - Stimulates fibroblasts -> subendothelial fibrosis - Complex inflammatory pathways -> alveolar and capillary damage - Mucus hypersecretion in response to inflammation - In exacerbation, an irritant such as a bacteria or a virus simply makes this worse than normal

Question 33

What symptoms do patients present with during COPD exacerbation? Why?

Answer 33

- Increased breathlessness (airway narrowing, increased bronchospasm) - Increased mucous production (goblet cell hyperplasia) - Increased sputum thickness (recruitment of neutrophils or, more rarely, eosinophils)

Question 34

Which is more likely to appear in older patients: COPD or asthma?

Answer 34

COPD

Question 35

When is asthma typically worse throughout the day? Is this the same for COPD?

Answer 35

Asthma: typically worse at night COPD: consistent (although can be characterised by increased cough in the mornings)

Question 36

Which of asthma and COPD cause persistent vs variable decreases in lung function?

Answer 36

COPD: Consistent Asthma: Variable

Question 37

Time course of asthma vs that of COPD

Answer 37

Asthma: Seasonal; no worsening COPD: Progressive worsening

Question 38

CXR in asthma vs COPD

Answer 38

COPD: Hyperinflation Asthma: Normal