Lung volumes and lung function testing Flashcards
What is lung compliance
Stretchiness
What is the lung like at higher pressure
Stiffer, so lower compliance
What is the lung like at lower pressure
Less stiff, more compliance
What part of the lung is more compliant than the apex
Base
What is lung compliance ensued by
Elastic recoil
What are some diseases where there is decreased compliance
Pulmonary fibrosis and alveolar oedema
When ay there be increased compliance
normal aging lung
What is lung compliance dependent on
Thoracic cage
For efficient ventilation, what do healthy people have
- High lung compliance
- Low alveolar surface tension due to surfactant (to stop lung collapsing)
What do tests of lungs need to test
- Mechanical condition of lungs
- Resistance of airways
- Diffusion acores alveolar membrane
What does a spirometer test and what is It dependent on
Lung volumes
-Lung’s elastic properties and the properties of the muscles of the chest wall
What is TV
volume of air moving into and out of the lung at rest
What is VC
Volume of air moving into and out of the lungs following forceful inhalation and forceful exhalation
What can you not measure using a spirometer
How much air is left in your lungs after forceful expiration
What is TLC
Tota lung capacity
What is FVC
Forced vital capacity -total volume exhaled
What should usually be the FVC
> 80% of the air inhaled should be expired out
How to measure lung function
Functional residual capacity
What is FRC measured using
Helium dilution (because helium is not metabolized) or nitrogen washout
Whats the procedure for nitrogen washout
- patient inspires 100% O2
- Expires into the spirometer system
- Procedure repeated until N2 in the lungs is replaced with O2
- FRC calculated from exhaled N2 and estimated alveolar N2
What is a restrictive deficit
Lung expansion is compromised- alterations in lung parenchyma, disease of the pleura or chest wall
-Lungs do not full to capacity hence they are less full before expiration
What is the FVC like in a restrictive deficit
Reduced
What is the FEV 1 like in restrictive deficit
Relatively normal
What is the FEV1/FVC like in a restrictive deficit
Normal/increased
