Obstructive Airway Diseases Flashcards
What are the main obstructive airway diseases?
- Chronic bronchitis
- Emphysema
- Asthma
Which of the main airway diseases are better known as CODP?
Chronic bronchitis and Emphysema
What is FEV1?
Forced expiratory volume of air exiting the lung in the first second of expiration
What is FVC?
Forced vital capacity
- Final total amount expired
- FEV1 is usually about 70-80% of FVC.
What is Spirometry?
Spirometry is a simple test used to help diagnose and monitor certain lung conditions by measuring how much air you can breathe out in one forced breath.
What can PEFR (Peak expiratory flow rate) be used for?
PEFR can be used to demonstrate obstructive lung disease.
What occurs in obstructive lung disease?
- There is airflow limitation!
- PEFR is reduced
- FEV1 is reduced!
- FVC may be reduced
- FEV1 is less than 70% of FVC
What does bronchial asthma cause?
Type I hypersensitivity in the airways
Is bronchial asthma reversible?
YES
Bronchial smooth contraction and inflammation can be modified by drugs or reversed spontaneously.
Aetiology of Chronic bronchitis and Emphysema
- Smoking
- Atmospheric pollution
- Occupation: dust
- Effect of age and susceptibility
Morphological changes in Chronic bronchitis in the large airways
- Mucous gland hyperplasia
- Goblet cell hyperplasia
- Inflammation and fibrosis is a minor component
Morphological changes in Chronic bronchitis in the small airways
- Goblet cells appear
- Inflammation and fibrosis in long standing disease
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 are the different forms of emphysema?
- CENTRIACINAR
- PANACINAR
- PERIACINAR
- SCAR
What is a bulla?
A Bulla is an emphysematous space greater than 1cm.
Pathogenesis of emphysema
- Smoking-protease, antiprotease imbalance
- Ageing
- Alpha-1-antitrypsin deficiency
Is airway obstruction in COPD reversible or irreversible?
Traditionally airways obstruction in COPD considered IRREVERSIBLE
…but this may not be completely true
Can we regrow alveolar walls that have been lost?
NO
What is normal PaO2?
10.5 - 13.5 kPa
What is normal PaCO2?
4.8 - 6.0 kPa
What 4 abnormal states are associated with Hypoxaemia?
- Ventilation/Perfusion imbalance
- Diffusion impairment
- Alveolar Hypoventilation
- Shunt
Would you give oxygen to COPD patients?
Yes but only small amount
How do large shunts respond to increases in FI blood leaving normal lung?
Large shunts respond poorly to increases in FI O2 Blood leaving normal lung is already 98% saturated
How is a decrease in PaO2 due to hypoventilation corrected?
By raising FIO2
FIO2 = the fraction of air inspired which is oxygen
Why does Pulmonary Hypertension occur?
- Pulmonary vasoconstriction!
- Pulmonary arterioles
- Loss of capillary bed
- Secondary polycynthaemia
