Most of us are familiar with the “breathing tests” that asthmatics and emphysema patients take to see how their disease is fairing either during a flare up or routine monitoring of the their medications—inhalers and such. Yet if you don’t have any lung disease, you are unlikely ever to have taken such a test. We, and many prominent pulmonary specialists, think that is unfortunate.(1)
Spirometry, as the breathing test is called, turns out to be a interesting biomarker of aging hiding in the clothing of pulmonary specialist’s test. While it certainly functions as a screen for early lung disease in undiagnosed asthmatics and smokers, it also measures the lung age of healthy individuals. In fact, in order to determine if the result of a spirometry test is abnormal, it must be compared to a large database of normal results adjusted for height, gender, ethnicity, and age. Spirometry performed by tens of thousands of individuals has resulted in large databases which can be used to determine lung age.
The complete testing session takes about 10 minutes. The patient takes as deep a breath as possible, places the airflow meter (pneumotach) in his mouth, then blows out the air as fast as possible in the first second. He then continues to blow for at least 5 seconds longer in an effort to completely empty his lungs. The computer attached to the pneumotach calculates the total amount of air expelled during the full exhalation, and the amount expelled in the first second. These measures are called the forced vital capacity (FVC), and the forced expiratory volume in the first second (FEV1), respectively. The procedure is repeated until 3 consistent measures are recorded.
Both the FVC and FEV1 decline after about age 25, but the FEV1 is the best marker. It declines about 1 to 2 percent per year as the graphs below depict.
These graphs show how FEV1 declines with age in males and females. (The first part of the curve increases because of the change in height during developmental years.)(2)