Pulmonary Function Tests and Treatment Options (L21) Flashcards
List the ways of testing lung function.
- Spirometry
- Peak flow meter
- Pulse oximetry
- Arterial blood gas analysis
- Flow volume loops
- Gas transfer (KCO) and transfer factor
What does Spirometry measure?
Lung volume, forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC).
What does a Peak flow meter measure?
Peak expiratory flow rate (PEFR).
What does Pulse oximetry measure?
Non invasive assessment of peripheral O2 saturation.
What does Arterial blood gas analysis measure?
pH, PaO2 and PaCO2.
What do Flow Volume loops measure?
Flow rates (expiration and inspiration and various lung volumes).
What does Gas transfer (KCO) and transfer factor measure?
Carbon monoxide uptake from a single inspiration.
Define Tidal volume.
State the average (ml).
Volume of gas inspired or expired during normal breath.
500 ml.
Define Inspiratory Reserve volume (IRV).
State the average (ml).
Volume of air that can be added to the TV during deepest possible inspiration.
3000 ml.
Define Expiratory Reserve volume (ERV).
State the average (ml).
The volume of air that can be moved out of lungs following the end of the maximum expiration.
1100 ml.
Define Residual volume (RV).
State the average (ml).
A maximum expiration does not completely empty the lungs. The RV is the volume of air left after maximal expiration.
1200 ml.
True or false? Residual volume (RV) can be measured directly.
False. Can not be measured directly. Measured indirectly through gas diffusion techniques involving inspiration of a known amount of harmless tracer gas.
Define Inspiratory Capacity (IC).
State the average (ml).
The maximum amount of air that can be inspired after a normal expiration (IRV + TV).
3500 ml.
Define Functional Residual Capacity (FRC).
State the average (ml).
The volume of air in the lungs at the end of a normal passive expiration.
2300 ml.
Define Total Lung Capacity (TLC).
State the average (ml).
Maximum amount of air that the lungs can hold (IRV+TV+ERV+RV).
5800 ml.
Define Vital Capacity (TLC)
State the average (ml).
The maximum amount of air that can be moved into and out of the lungs in a single breath (IRV+TV+ERV).
4600ml.
Using the lung equations/symbols, describe the lung volumes in obstructive lung diseases.
- Patients with obstructive lung disease experience difficulty emptying lungs
- TLC is normal
- FRC and RV elevated due to air trapped in lungs
- As RV increases VC decreases
Using the lung equations/symbols, describe the lung volumes in restrictive lung diseases.
- The lungs are less compliant
- TLC, IC and VC are down as lungs can not expand as normal
- RV is normal
Define FEV1.
The forced expiratory volume in one second. It reflects airway narrowing and is relatively independent of effort.
Define FVC.
The forced vital capacity.
True or false? Normally FEV1 = 80%-90% of the FVC.
False. Normally FEV1 = 70%-80% of the FVC.
True or false? FEV1 and FVC are used to differentiate between obstructive and restrictive patterns of disease.
True.
In Obstructive lung disease what happens to FEV1 and FEVC.
How can this be used to determine whether the disease is restrictive or obstructive?
- FEV1 is reduced
- FEVC is reduced to a lesser extent
- Therefore the ratio changes which means the disease is obstructive
In Restrictive lung disease what happens to FEV1 and FEVC.
How can this be used to determine whether the disease is restrictive or obstructive?
- FEV1 and FVC decrease to same extent
- Therefore the ratios remain the same which means the disease is restrictive
