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PulmoAge - Lung Capacity Testing

 

From screening to lung age. Spirometry turns out to be an informative biomarker of aging hiding in the guise of a pulmonary specialist's test. While it certainly functions as an excellent screen for early lung disease in symptomatic, 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 healthy adults 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.


Vital Capacity. The two main results of spirometry are:
» Forced vital capacity (FVC): the total amount of air you can force out after a maximal inhalation
» Forced expiratory volume in the first second (FEV1): the maximum amount of air you can force out in the first second of your forced vital capacity exhalation.

 

FVC is determined by the size of your chest, the number and health of the air sacs (alveoli) where gas exchange takes place, the elasticity of your large airways, and the strength of your breathing muscles. The FEV1 is largely determined by the elastic recoil of the air the small airways.

 

Why is the PulmoAge important?
» Many large studies, including those that tracked people over long periods, have shown that both the FVC and FEV1 decline with age - about one percent a year.


» Screen for pulmonary disease. If FEV1/FVC < 0.72, the patient could have obstructive pulmonary disease.


» There is a correlation between these biomarkers and mortality. One investigation, the Buffalo Health Study, followed nearly 1,200 men and women between the ages of 20 and 89 for twenty-seven years, and found that lower
lung function predicted earlier death.


» While spirometry results can be predictive of mortality risk, the correlation is not solely between respiratory function and death caused by respiratory disease. This is where the picture becomes a bit ambiguous, and where it deviates from other biomarkers of aging. Arterial stiffness, for instance, correlates directly with lifethreatening cardiovascular disease. But while the average person's FEV1 can be expected to decline about one percent a year - and that can add up to a significant percentage of functional loss over the course of a lifetime - such normal lung aging is not going to cause early death from lung disease in most people. As the studies cited above indicate, the more significant association is between lower spirometry readings and increased mortality of all kinds. These findings bolster the idea that respiratory function over time reflects how well the body as a whole is aging, making spirometry one of the most valuable biomarkers of aging.


“We consider FEV1 as a surrogate for a number of unmeasured aging processes ... and not as a specific measure of lung function.”

— Dr. Milton Hollenberg

University of California, San Francisco Medical Center


What factors affect the PulmoAge?

Many of the same factors that affect CardioAge also affect PulmoAge. PulmoAge is adjusted for height and gender, but differences in the structure of the chest, barrel vs. narrow, can also affect it. Smoking affects the lungs directly and indirectly, by affecting the arteries supplying the lungs with oxygen. Asthma/emphysema inhaled medications such as bronchodilators and anti-inflammatories can improve the FEV1 and FVC.

 

Taking a baseline PulmoAge test and repeating it annually is an effective way to see how well your anti-aging treatments are working. If there is no significant increase over time, you're doing something right. In addition, a baseline test can tell you if your patient is at significant increased risk for lung disease and can motivate a smoker to quit.

 

 

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)

 

1.           Petty TL. Testing patients' lungs: spirometry as part of the physical examination. Clin Ther. 1999;21(11):1908-22.

2.           Hankinson JL, Odencrantz JR, Fedan KB. Spirometric Reference Values from a Sample of the General U.S. Population. Am. J. Respir. Crit. Care Med. 1999;159(1):179-187.

3.           Schunemann HJ, Dorn J, Grant BJB, Winkelstein W, Jr., Trevisan M. Pulmonary Function Is a Long-term Predictor of Mortality in the General Population: 29-Year Follow-up of the Buffalo Health Study. Chest. 2000;118(3):656-664.

4.           Hollenberg M, Yang J, Haight TJ, Tager IB. Longitudinal changes in aerobic capacity: implications for concepts of aging. J Gerontol A Biol Sci Med Sci. 2006;61(8):851-8.

 

Sample report (PDF)

 

Spirosamplesm

 

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