03.2 Lung Function Test Flashcards
What is tidal volume?
The volume in and out with each breath.
What is the inspiratory reserve volume?
Extra volume that can be breathed in.
What is the expiratory reserve volume?
Extra volume that can be breathed out.
What is the residual volume?
Volume remaining after maximum expiration.
What is vital capacity and how can it be calculated?
Max inspiration to max expiration. IRV+TV+ERV
What is the inspiratory capacity?
Biggest breath that can be taken from resting expiratory level.
What is the functional residual capacity?
Volume of air in lungs at resting expiratory level. ERV+RV
What is total lung capacity?
Volume if gas in the lungs at the end of maximal inspiration. IRV+TV+ERV+RV
What is FVC?
Forced vital capacity.
What is FEV1.0?
Volume expired in the first second.
What is a normal FEV/FVC ratio?
>70%
If the green curve is normal, what pattern does the blue curve represent?
Obstructive
If the green curve is normal, what does the orange curve represent?
Restrictive
What happens to the FEV/FVC ratio in obstructive diseasees?
Decreases
What happens to the FEV/FVC ratio in restrictive diseases?
Increases.
How can asthma be investigated using spirometry?
Check reversibility of obstructive pattern before and after bronchodilator use.
What type of pattern is shown in red here?
Restrictive
What type of pattern is shown in red here?
Obstructive
How can residual volume be calculated?
Helium dilution.
Patient breathes in a known volume of helium which is diluted in the lungs. Clever maths is then used to calculated how much total volume is left from what is breathed out.
What can be done to calculate serial/anatomical dead space?
Nitrogen washout.
Breathe in pure oxygen. Initial air breathed out is pure O2. This gradually becomes a mix of O2 and alveolar gas which continues to a plateau where exhaled gas represents alveolar gas. You can then use Fowler’s method to calculate deadspace.
What is Fowler’s method?
Vertical line drawn so that the area of A = B.
The volume at the vertical line is the anatomical deadspace.
How can diffusion be measured?
Diffusion conductance - CO transfer factor.
Patient breathes in a known concentration of carbon monoxide which is then measured for in the blood to calculate rate of diffusion.
