Chronic Bronchitis

Question 1

What is Chronic Bronchitis? Give a brief description/definition.

Answer 1

Defined as chronic cough with sputum prod’n for 3 or months in 2 or more consecutive years.

Itis an obstructive pulmonary disease that progresses to COPD.

It is caused by long-standing irritation of the lungs by cigarette smoke, smog, etc.

Question 2

Describe the pathogenesis of Chronic Bronchitis.

Answer 2

1. Inhaled irritant stimulate neutrophils to release proteases which, in turn, stimulate sub-mucosal glands in the large airways to increase sputum production.
2. Chronic hypersecretion -> hyperplasia and hypertrophy of these mucus glands.
3. If irritant persists, goblet cells in small airways also undergo hyperplasia and hypertrophy - airway obstruction.
4. This obstruction as well as direct small airway damage leads to COPD.

Question 3

Describe the characteristic changes associated with Chronic Bronchitis.

Answer 3

Chronic irritation of the airways leads to:

• Hyperaemia and oedema of the mucus membranes of the lung.
• Mucinous secretions +/- casts obstructing airways.
• Hypertrophy and hyperplasia of mucus glands and goblet cells.
• Bronchial and/or bronchiolar mucus plugging, inflam’n and fibrosis.
• Squamous metaplasia.

Question 4

What is the role of infection in Chronic Bronchitis?

Answer 4

Infections are a secondary process that maintain and promote the airway inj’y induced by the responsible irritant.

Question 5

What is the charcteristic histologic feature of chronic bronchitis? *

Answer 5

Enlarged mucus-secreting glands of the trachea and bronchi.

Question 6

What is the earliest feature and hallmark of Chronic Bronchitis? *

Answer 6

Hypersecretion of mucus in the large airways.

Question 7

How much more common is Chronic Bronchitis in smokers? *

Answer 7

Chronic bronchitis is up to 10x more common in heavy smokers.

Question 8

What can Chronic Bronchitis progress to? *

Answer 8

COPD -> cor pulmonale -> cardiac failure -> death

Question 9

What is the Reid Index? What is its normal value and what happens to this measurement in chronic bronchitis? *

Answer 9

The Reid Index is a ratio of the mucus gland layer to the thickness of the bronchial wall from epithelium to catilage.

The normal value is 0.4.

In chronic bronchitis the Reid Index increases and is a marker of disease severity.