RV is one of several factors thatpulmonologistsmeasure duringpulmonary function testingto determine how well your lungs are working.
This article describes what residual volume is and why and how it is measured.
It also explains what abnormal values mean and when it is time to see a healthcare provider.
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Why Do We Need Residual Volume?
Residual volume is needed because without some air in the lungs at all times, they would collapse.
Residual volume is also important as it prevents fluctuations in oxygen and carbon dioxide levels in the lungs.
Neither oxygen nor carbon dioxide becomes “trapped” and accumulates.
How Is Residual Volume Measured?
Residual volume is the volume of air in the lungs in milliliters (mL) after a maximum exhalation.
How the ERV Is Measured
The expiratory reserve volume is measured with a simple equipment called aspirometer.
At the end of a normal exhalation, you will be asked to breathe with force into the spirometer.
The volume of air expelled during this exhalation is your ERV.
The average ERV is about 1200 milliliters (mL) in males and 700 mL in females.
How the FRC Is Measured
The FRC is not as simple to measure as the ERV.
A normal FRC in most healthy adults is between 3000 mL and 4000 mL.
Females tend to run along the lower range of values.
RV values can also be used to monitor your response to treatment.
Examples includeobesityandkyphosis(a spinal deformity, also known as “hunchback”).
In acute, severe cases, difficulty breathing can be an emergency.
Call 911 immediately, as some causes of shortness of breath may be life-threatening.
It is calculated based on the results of spirometry and other pulmonary function tests.
Lutfi MF.The physiological basis and clinical significance of lung volume measurements.Multidiscip Respir Med.2017;12(3).
