tutorial 8 - obstructive lung diseases Flashcards
What diseases are grouped together under the term Chronic Obstructive Pulmonary Disease (COPD)?
Emphysema, chronic bronchitis
What is emphysema?
Destruction of the airspaces distal to the terminal bronchioles resulting to their irreversible enlargement and damage.
What is centracinar emphysema?
Destruction of the respiratory bronchioles with normal distal alveoli
What is the gross morphology of a lung with centriacinar emphysema?
Holes in the lung parenchyma representing emphysematous air spaces (dilated respiratory bronchioles)
What is the term for deposition of carbon pigment in the lungs due to smoking?
Anthracosis
What is the pathogenesis of emphysema?
Cigarette smoking/inhaled pollutants produce oxidants that cause inflammation. Inflammatory cells release proteases that destroy elastic tissue in airspace walls
What is bullous emphysema?
When emphysema becomes advanced and several dilated airspaces join together forming large bubbles
what are the findings of a chest xray of a patient with emphysema?
flattened diaphragm, hyperinflated chest, decreased bronchovascular lung markings
What action do patients with emphysema commonly do to compensate for airways collapse?
Purse their lips when breathing - ‘pink puffers’
Why do patients with emphysema develop barrel chests?
Due to air trapping in enlarged spaces in the lungs
Why is emphysema an obstructive lung disease?
Because there is obstruction to expiration as the lungs lose their elastic recoil
What symptoms must be present, and for how long, for a diagnosis of chronic bronchitis?
persistent productive cough for most days in 3 months over 2 years
What is the initiating factor for chronic bronchitis?
Cigarette smoke/inhaled chemicals
What is the pathogenesis of chronic bronchitis?
- smoking causes chronic bronchial inflammation
- inflammation causes bronchial wall to undergo metaplasia of epithelium, hypertrophy and hyperplasias of mucus secreting glands
- mucus hyper secretion causes productive cough and airways obstruction.
What are the features of a chest xray of a patient with chronic bronchitis?
Prominent vessels, large heart
Which type of COPD causes ‘blue bloaters’?
Chronic bronchitis
What type of COPD causes ‘pink puffers’?
Emphysema
What type of hypersensitivity reaction is involved in an acute asthma exacerbation?
Type 1
What is the pathogenesis of atopic/extrinsic asthma?
- exposure to allergen triggers IgE on mast cells in the airways.
- mast cells degranulate and release cytokines that recruit eosinophils, increase mucus production and stimulate further IgE production
- IgE crosslinks leading to degranulation and bronchoconstriction, increased vascular permeability and oedema, mucus production and leukocyte recruitment.
- In the late phase, eosinophils produce proteins that damage the airway epithelium
What are the changes that occur in the airways due to remodelling caused by repeated allergen exposure and asthma exacerbations?
basement membrane thickening, hypertrophy of bronchial smooth muscle, hypertrophy of mucus glands and hyperplasia of goblet cells, damaged epithelium, chronic eosinophil infiltration, air trapping
What are the findings on a chest xray of a patient with acute severe asthma?
hyperinflated chest, flattened diaphragm, but preserved lung markings
What is bronchiectasis?
Permanent dilation of bronchi and bronchioles due to destruction of their walls
What causes bronchiectasis?
Repeated cycles of infection with subsequent destruction of the bronchial smooth muscles and elastic tissue with healing via fibrosis
Why do conditions causing bronchial obstruction often lead to bronchiectasis?
Because they predispose chronic or recurrent infections
