Pathology of Obstructive Lung Disease Flashcards
Name 3 chronic obstructive diseases
- Chronic bronchitis
- Emphysema
- Asthma
How do chronic bronchitis, emphysema and asthma differ?
The method that they obstruct the airway is different
What is the collective term for chronic bronchitis and emphysema?
COPD
What does FEV1 stand for?
Forced Expiratory Volume in 1 second
What does FVC stand for?
Forced Vital Capacity
What are the normal values for the FEV1/FVC ratio?
- FEV1 usually 70-80% of FVC
What does spirometry test?
If the airways are obstructed
What test do asthmatics use at home to test their airways?
Peak flow
What is normal peak flow range?
80-100% of best recorded value
What results of peak flow, FEV1 and FVC do you expect to see with obstructive disease?
- Low peak flow
- FEV1 reduced
- FVC possible reduced
- FEV1 less than 70% of FVC
What causes bronchial asthma?
- Type 1 hypersensitivity in the major airways
What causes the bronchial constriction in the airway?
- Degranulation of mast cells
- Release of histamine and other chemotactic factors
What two ways can bronchial asthma be reversed?
- On it’s own
- Through treatment
What 3 environmental factors can result in COPD?
- Smoking
- Pollution
- Occupational dust
What can a deficiency in alpha 1 antitrypsin lead to?
Emphysema
What happens to a persons FEV1 curve when they stop smoking?
- Damage is already done
- FEV1 keeps declining but now only at the same rate as a normal person
What is the clinical definition of chronic bronchitis?
A sputum producing cough in 3 months for 2 years
During chronic bronchitis what morphological changes do the large airways undergo?
- Mucous gland hyperplasia
- Goblet cell hyperplasia
- Inflammation and fibrosis
Pathological definition of emphysema?
- Increase in size of distant bronchioles
- Size increases from either breakdown of walls or dilation
What is the terminal bronchiole?
- Last conducting bronchiole
Where is centriacinar emphysema located?
Proximal resp bronchioles (apex of upper and lower lobes)
Progression of centriacinar emphysema?
- Bronchiolar dilation
- THEN loss of alveolar tissue
What is a bulla?
- Space greater than 1cm in the distal airways caused by emphysema
What is a bleb?
Bulla directly underneath the pleura
What happens when a bleb bursts?
Pneumothorax
What should be apparent on a chest X ray of a person with emphysema?
Hyperinflation of the lungs
What does inflammation in the lungs release which can end up being a problem?
- Elastases (proteases) which can break down the walls between bronchioles
What normally happens to elastase?
There is an equilibrium between elastase and anti-elastase
What does smoking do to the equilibrium of elastase and anti elastase?
Fucks it up
Which aspect of the equilibrium does smoking fuck up?
- Reduces anti elastase levels
- Increases elastase levels
- Increases neutrophils and macrophages
What is the most important development in emphysema?
- Loss of alveolar attachments
Why is it impossible to completely exhale your entire residual volume?
Small airways close
What are the 4 abnormal states that can result in hypoxaemia?
- V/Q mismatch
- Shunt
- Alveolar hypoventilation
- Inability to diffuse
How does the V/Q mismatch lead to hypoxaemia?
- Some alveoli not ventilated well
- Occasionally blood gets through that is not oxygenated
- The more non ventilated alveoli the worse the effects
How does alveolar hypoventilation lead to hypoxaemia?
Reduces the respiratory drive
How does inability to diffuse result in hypoxaemia?
Loss of alveolar surface area
What conditions show a V/Q mismatch?
- Bronchitis
- Bronchopneumonia
When would shunt be seen?
- Severe bronchopneumonia
Why does a lot of blood need to not be oxygenated for shunt?
- Has to be enough so a lot of unoxygenated blood mixes with oxygenated blood
- Large area of lung has to be non ventilated to mean that no gas exchange occurs
What is normal ventilation?
4L/min
What is normal cardiac output?
5L/min
What is normal V/Q?
4/5 so 0.8
How can hypoxaemia due to low V/Q be countered?
- Increasing FIO2
- Usually through breathing oxygen
When will treating hypoxaemia due to V/Q not help?
When it is a result of shunt
How can you tell shunt is pathological?
- AV malformations
- Congenital heart disease
- Pulmonary disease
What does FIO2 stand for?
Fraction of inspired air that is oxygen
What does hypoventilation result in?
- Increases PACO2
- Decreased PAO2
Why is it important to monitor someone with COPD placed on oxygen?
- Respiratory centre becomes oblivious by the effects of CO2 and H ions and therefore lose their resp. drive
- Rely on hypoxia to breathe
- If hypoxia is reduced then they will stop breathing
What is chronic cor pulmonale?
- Right ventricular heart failure due to pulmonary hypotension secondary to a pulmonary vascular disease
What can occur on a chest x ray to the heart of COPD sufferers
Increase in right ventriclular muscle
