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.
In chronic bronchitis what changes occur to the large airways?
Mucous gland hyperplasia (increase in mass, so can increase by size and number)
Goblet cell hyperplasia
Inflammation and fibrosis plays a small role
What changes occur to small airways in chronic bronchitis?
Goblet cells appear (they are not normally found in the small airways)
Inflammation and fibrosis can be found in long standing disease.
How does emphysema effect gas exchange?
It reduces the surface area available for gas exchange, so the PAO2 would be normal but PaO2 would be low.
What is the pathological definition for emphysema?
Increase in size of the airspaces distal to the terminal bronchioles (the alveoli) from the normal. This is caused by either the dilation or destruction of their walls and is without obvious fibrosis.
What are the different types of emphysema?
Centriacinar Panacinar Periacinar SCAR 'irregular' Bullous emphysema
Which type of emphysema is most associated with smoking?
Centriacinar
Explain where panacinar emphysema is found
It affects all parts of the secondary pulmonary lobule and is often found at the base of the lung.
This is often associated with an alpha antitrypsin deficiency. It wipes out all forms of lung tissue in acinars.
It is less common but causes more damage.
What is a bulla?
It is an emphysematous space greater than 1cm.
What is a bleb?
It is a bulla just underneath the pleura.
What happens if a bulla bursts?
It can cause spontaneous pneumothorax.
What are the causes of emphysema?
Smoking
Protease- antiprotease imbalance (e.g. alpha-1 antitrypsin deficiency)
