Lung Function Tests and Values Flashcards
What does the flow volume loop measure and what is it used for?
It is a standard measure of pulmonary function and can provide a graphic representation of numberous pulmonary disorders. Many pulmonary diseases have a characteristic flow-volume loop. Positive numbers represent expiration, negative values represent inspiration. A scooped out upper portion of the loop represents COPD and a smaller loop all around represents restrictive disease.
What are the 2 most important measures of simple spirometry and what do they measure?
FEV1 (L): - amount of air blown out in the first second of a forced exhalations after a maximal inhalation
FVC (L): - total amount of air blown out from a forced exhalation after a maximal inhalation
The ratio of FEV1/FVC in the healthy person is at least 70%.
How do you perform spirometry?
Before and after use ofa bronchodilator (ventolin) to determine bronchodilator responsiveness.
Obstructive vs. restrictive disease. With regards to FEV1 and FVC how do you classify obstructive?
Airflow is obstructed when leaving the lungs - lung volumes are greater due to trapped air therefore FEV1 is greatly reduced. FVC is a little bit reduced or could be normal. The ratio of FEV1/FVC is reduced.
Obstructive vs. restrictive disease. With regards to FEV1 and FVC how do you classify restrictive disease?
Chest expansion is restricted so air entering the lungs is less; lung volumes are less; have a hart time breathing in general; FVC is reduced; FEV1 is reduced. The ratio of FEV1/FVC is normal or even increased.
Define tidal volume.
The volume of air in and out of lungs during quiet breathing (L).
Inspiratory reserve volume.
Maximal volume of air that can be inhaled from the end-inspiratory level.
Residual Volume.
The volume of air remaining in the lungs after a maximal exhalation.
Expiratory reserve volume.
The maximal volume of air that can be exhaled from the end-expiratory position.
Inspiratory capacity
The sum of inspiratory reserve volume and tidal volume.
Vital Capacity
Inspiratory reserve volume plus tidal volume plus expiratory reserve volume. The amount of air that is under volitional control. Conventionally measure as FVC.
Functional residual capacity.
The amount of air that resides in the lungs after a normal resting tidal exhalation.
Total lung capacity.
The total amount of air that is housed within the thorax during a maximum inspiratory effort.
Define diffusing capacity.
Measures the exchange of gas across the alveoli using CO. Provides confirmation of diagnosis of emphysema.
Define dead space.
that part of inspired air that is exhaled without the benefit of exposure to perfused alveoli.
