Obstructive Airway Disease Flashcards
What diseases or conditions may be mistaken for obstructive airway diseases?
Tumours, FBs, chronic scarring, bronchiectasis, TB etc are associated with obstruction of a large airway = local obstruction. These are not primarily obstructive diseases.
What are the three big OADs?
Chronic bronchitis
Emphysema
Asthma
What is COPD?
Chronic bronchitis and emphysema.
(chronic obstructive pulmonary disease)
CB and E almost always go together. Few genetic conditions where only E.
What are FEV1 and FVC and how can they be used to test lung function?
FEV1 - forced expiratory volume of air exiting lungs in first second after taking deep breath in and trying to blow as much air out as quickly as possible.
FVC = forced vital capacity.
FEV/FVC normally = 70-80%.
What are the norm values for FEV1, FVC and FEV1/FVC?
FEV1 = 3.5-4L
FVC = 5L
FEV1:FVC - 0.7/0.8
How can spirometry be used to measure lung function?
Can determine FEV1, FVC and compare to predicted.
What are your predicted values based on?
Age, sex, height.
Obstructive lung disease may also be demonstrated by PEFR, what is this?
Peak expiratory flow rate (PEFR). 50-80% of best is moderate fall. <50% of best is marked fall. 80-100% of best best value = normal. Normal 400-600 L/min
What is the key thing about obstructive lung disease?
There is airflow limitation.
Meaning PEFR and FEV1 are reduced, FVC may be reduced. FEV1 is less than 70% of FVC.
What is bronchial asthma?
Type 1 hypersensivity in the airways.
Airways obstructed by inflammation (degranulation of mast cells). Constriction of smooth muscle around airways, overproduction of mucus –> narrowing of airways and airway irritation.
Reverses in time and as a result of medication. (inflammation also modified by drugs)
What are the aetiologies of COPD?
Smoking, atmospheric pollution, dust.
As age increases susceptibility increases.
More prevalent in men.
Increasing prevalence in developing countries.
What is a rare cause of emphysema?
Alpha-1-antiprotease (antitrypsin) deficiency is an extremely rare genetic cause.
Describe the effect of age and smoking on lung function.
In 20s have optimum lung function, as age increases lung function decreases. Non-smoker/not susceptible to smoke lung function decreases at a very slow rate, and they should never really experience lung problems.
Smoker’s lung function will decrease v. rapidly, and they will experience lung problems at a younger age.
If you manage to stop smoking in mid 40s then rate of decline returns to normal, damage will not be repaired but lung function will not deteriorate as quickly.
Define chronic bronchitis clinically?
Cough productive of sputum most days, in at least 3 consecutive months for 2 or more consecutive years.
EXCLUDES TB, bronchiectasis etc.
What is complicated chronic bronchitis?
When mucopurulent (yellow/green mucus) (acute infective exacerbation) or FEV1 falls.
Describe the morphological changes in the large airways in chronic bronchitis.
Mucous gland hyperplasia.
Goblet cell hyperplasia.
Inflammation and fibrosis is a minor component.
Describe the morphological changes in the small airways in chronic bronchitis.
Goblet cells appear.
Inflammation and fibrosis in long standing disease.
= airways narrower, lumen smaller –> airflow limitation.
What is the pathological definition of emphysema?
Increase beyond the normal in the size of airspaces distal to the terminal bronchiole arising either from dilatation or from destruction of their walls and without obvious fibrosis.
What is an acinus?
Respiratory bronchioles and alveoli.
What are the different forms of emphysema?
Centriacinar Panacinar Periacinar Scar - irregular Bullous emphysema