W4 - Obstructive Lung Diseases Flashcards
Name 4 obstructive airway diseases
Chronic bronchitis
Emphysema
COPD (Chronic bronchitis + emphysema)
Asthma
Define FEV1 and FVC
FEV1 is Forced Expiratory Volume - air exiting lung in first second
FVC - Final total of air expired
What is the typical value of FEV1 and FVC in litres and as a ratio? How does obstructive disease change these values?
FEV1:FVC ratio: 70-80% (or 0.7-0.8)
FEV is 3.5 - 4 litres
FVC is 5 litres
In obstructive disease:
FEV1 is reduced
FVC may be reduced
Ratio is less than 70%
How are spirometry valuees predicted?
Predicted FVC is based on age, sex and height
What is normal PEFR value?
400 - 600 litres/min
Which obstructive disease is a Type I Hypersensitivity Response? Mast cell degranulation leads to what two things?
Bronchial asthma
Mast cell degranulation leads to factors attracting inflammatory cells and factors causing smooth muscle contraction
The airway of chronic asthma exhibits what 5 features?
Inflammation
Oedema
Mucus
Plasma exudation
Epithelial shedding/damage
Name 7 COPD aetiologies
Smoking
Air pollution
Jobs
Alpha-1 Antitrypsin deficiency
Age and susceptibility
Men more than women
Developing countries increasing
Provide the clinical definition of chronic bronchitis
Cough productive of sputum most days
in at least 3 consecutive months
for 2 or more consecutive years
When does chronic bronchitis become complicated chronic bronchitis? (2 ways)
When sputum turns mucopurulent
or FEV1 falls
What morphological changes does chronic bronchitis lead to in large airways? (3 ways)
Mucous gland hyperplasia
Goblet cell hyperplasia
Inflammation and fibrosis is a minor component
What morphological changes does chronic bronchitis lead to in small airways? (2 ways)
Goblet cells appear
Inflammation and fibrosis in long standing disease
Provide the pathological definition of emphysema
Increase beyond normal size of airspaces distal to terminal bronchiole arising from dilation or destruction of their walls, without obvious fibrosis
Name 4 forms of emphysema
Centriacinar
Panacinar
Periacinar
Scar “irregular” / bullous emphysema
What is the most common form of emphysema? What is it characterised by? Where does it occur in the lung? What is it most associated with?
Centriacinar Emphysema
Where tissue around acini are damaged, making holes in the middle of them
Occurs in upper lobes
Associated with smoking
What is panacinar emphysema characterised by? What causes it? Where does it happen in lungs?
Rare emphsema where whole acini is destroyed
Caused by Alpha-1 Trypsin Deficiency
Tends to be base of lungs
What is periacinar emphysema? What complication can it lead to?
Damage on edge of acini, with space under pleura. Spontaneous busting can cause pneumothorax
What is a bulla and bleb?
Bulla - an emphysematous space of 1cm+
Bleb - describes the space just under pleura
What 3 things cause emphysema?
Smoking
Ageing
Alpha-1 Antitrypsin Deficiency
While COPD is irreversible, which 2 mechanisms of the disease respond to pharmacological intervention?
Smooth muscle tone
Inflammation
What 4 things cause hypoxaemia in COPD?
Airway obstruction
Reduced respiratory drive
Loss of alveolar surface area
Shunt (during severe acute infective exacerbation)
Explain the steps leading to cor pulmonale in COPD
- Alveoli short of oxygen
- Pulmonary arteriolar vasoconstriction to avoid sending blood to oxygen-poor alveoli.
- Pulmonary hypertension
- Muscle hypertrophy in pulmonary arterioles and intimal fibrosis
- Loss of capillary bed
- Secondary polycythaemia
- Bronchopulmonary arterial anastamoses
Hypertrophy of right ventricle, affecting function and/or structure of lung
