Pathology of Obstructive Lung Disease Flashcards
What is the normal value for FEV1?
3.5-4 litres
What is the normal value for FVC?
5 litres
What is the normal ratio for FEV1:FVC?
0.7-0.8
What % is FEV1 of FVC?
70-80%
Which factors may influence FEV1 and FVC?
Age, height and sex
What is the average peak rate of flow? (PEFR peak expiratory flow rate)
400-600 litres/min
Describe the values of PEFR, FEV1, FVC in those with obstructive lung disease.
Peak Expiratory Flow Rate (PEFR) is reduced
FEV1 is REDUCED
FVC may be reduced
FEV1 is less than 70% of FVC
What is the most common cause of chronic bronchitis and emphysema (COPD)?
Smoking :)
Which extremely rare deviancy can lead to emphysema alone?
Alpha-1-antiprotease (antitrypsin) deficiency
Do individuals usually only have emphysema or chronic bronchitis or do they more often have both?
Both
What is the clinical definition of chronic bronchitis?
Cough productive of sputum most days in at least 3 consecutive months for 2 or more consecutive years
What may chronic bronchitis be confused with clinically?
Chronic bronchial asthma
When does complicated chronic bronchitis happen?
When sputum turns mucopurulent (acute infective exacerbation) or FEV1 falls
What are some of the morphological changes in the large airways of those with chronic bronchitis?
Mucous gland hyperplasia
Goblet cell hyperplasia (increased in number)
Inflammation and fibrosis is a minor component
What are some of the morphological changes in the small airways of those with chronic bronchitis?
Goblet cells appear
Inflammation and fibrosis in long standing disease
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 the most common form of emyphesma?
Centriacinar emphysema
What is the pulmonary acinus?
Gas-exchanging unit of the lung and is defined as that portion of the lung distal to the terminal bronchiole which is composed of the respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli.
Which part of the lungs is Centriacinar emphysema most common?
Upper part of the lungs
Name some other types of emphysema.
Panacinar
Periacinar
Scar ‘irregular’
Where is there tissue loss in periacinal emphysema?
Around the edges of the acinus
What is a bulla?
Bulla is an emphysematous space greater than 1cm
What happens if a bulla pops or leaks gas?
A pneumothorax may form as air leaks into the pleural space
Which cells in the lungs can cause slight inflammation as they digest foreign substances?
Neutrophils and macrophages
What do neutrophils and macrophages produce?
Elastase (protease)
Why is it important that we don’t have too much elastase in our lungs?
It digests the elastase framework of alveolar tissue
What is the counteraction for elastase to maintain homeostasis?
Anti-elastase :)
How effective are the repair mechanisms for the elastin synthesis in the lungs?
Very poor
What is not present in those with alpha 1 antitrypsin deficiency?
Anti-elastase :(
What does the lack of anti-elastase lead to?
Tissue destruction->emphysema
What does smoking do to the production of elastase and antielastase?
Decreases ant elastase
Increases activity of neutrophils and macrophages so there is more elastase produced
Which part of the small airways may respond to drugs?
-smooth muscle tone
-inflammation
How does emphysema lead to obstructive airways?
Loss of alveolar attachments
Name some factors which contribute to hypoxaemia.
Airway Obstruction
Reduced Respiratory Drive
Loss of Alveolar Surface Area
Shunt - Only during severe acute infective exacerbation
What happens to pulmonary arteriolar vasoconstriction when there is hypoxia?
All vessels constrict preventing blood from going to oxygen poor alveoli as gas exchange will not take place efficiently
What is chronic cor pulmonary?
Hypertrophy of the Right Ventricle resulting from disease affecting the function and/or the structure of the lung.
What is the main cause of death in patients with COPD?
Cor Pulmonale and right heart failure
How does emphysema impacts blood vessels?
Reduces numbers of blood vessels.
Explain Secondary polycythaemia
Bone marrow produces more red blood cells as not enough oxygen is carried around the body.
However, this just increases viscosity of blood making it harder to be pumped.
