Obstructive Lung Disease Flashcards
How do obstructive lung diseases affect the lungs?
They all obstruct airways in the respiratory system, they all achieve this through different mechanisms.
How do obstructive lung diseases affect FEV1/FVC?
Both FEV1 (forced expired volume in 1 second) and FVC (final total amount) will decrease but FEV1 will decrease much more than FVC. So the FEV1/FVC ratio will decrease.
What is shunt?
It is when some alveoli are being poorly ventilated, so that the blood flowing past them is not being oxygenated.
What occurs as a response to a shunt?
Vasoconstriction and bronchial dilation.
What is PEFR?
It is peak expiratory flow rate.
The normal range is 80-100% of the best value for that patients age, height and sex..
50-80% of best is a moderate fall
<50% is marked fall
How many times must you take a PEFR reading?
3 times and use the best score of the 3
What are key components of an obstructive lung disease diagnosis?
Reduced PEFR
FEV1 is reduced and is less than 70% of FVC.
FVC may be reduced.
There is airflow limitation.
Name some examples of types of obstructive lung disease.
Asthma COPD (chronic bronchitis + emphysema) Empysema Chronic bronchitis Bronchiectasis Cystic Fibrosis
How is chronic bronchitis clinically defined?
A cough that produces sputum most days in at lest 3 consecutive moths for 2 or more consecutive years.
What morphological changes occur in large airways in chronic bronchitis?
Mucus gland and goblet cells increase in size and number
Inflammation and fibrosis play minor roles.
What morphological changes occur in small airways in chronic bronchitis?
Goblet cells form, these are not usually found in small airways
Inflammation and fibrosis can be found in long standing disease.
Why is an increased amount of mucus (and goblet cells) produced in chronic bronchitis?
It is a protective measure to try and prevent the airways from getting irritated. However the mechanism gets out of control and too much mucus is produced.
What factors contribute to the narrowing of airways in chronic asthma?
Inflammation Oedema Mucus Plasma Exudate Inappropriate constriction of the smooth muscle.
Is the airway obstruction in asthma reversible?
Yes, either spontaneously or as a result of medical intervention (drugs)
What are the main causes (aetiology) of COPD?
Smoking
Atmospheric pollution
Occupational exposure such as dust.