About lung age – Welch Allyn CP 200 Spirometry Option - User Manual User Manual
Page 75
Directions for Use
Appendix D Predictive Norms, etc.
71
About Lung Age
Lung age is a calculated value based on a patient’s demographics and spirometric
performance that gives a relative indication of the health of the subject's lungs. This value
is used primarily to encourage smoking cessation.
The CP 200 spirometer, calculates lung age values according to the document cited in
on page 75 (Morris 1995). For single-effort tests, lung age is based on the
current effort. Otherwise, it is based on the patient’s “best” effort, as defined in the
settings.
Lung age results less than 20 years are reported as “<20,” and results greater than 84 are
reported as “>84.” This limitation is derived from the subject population on which Morris
based his research.
Lung age, which is expressed in years, is the average of the four formulas in the Morris
article (FVC, FEV1, FEF25-75%, and FEF0.2-1.2). Specifically, lung age is calculated as
follows:
Gender
Lung Age Formula
Men
[5.920 (height) – 40.000 (FVC) – 169.640 +
2.870 (height) – 31.250 (FEV1) – 39.375 +
2.319 (height) – 21.277 (FEF200-1200) + 42.766 +
1.044 (height) – 22.222 (FEF25%-75%) + 55.844 ] / 4
Women
[4.792 (height) – 41.667 (FVC) – 118.833 +
3.560 (height) – 40.000 (FEV1) – 77.280 +
4.028 (height) – 27.778 (FEF200-1200) – 70.333 +
2.000 (height) – 33.333 (FEF25%-75%)+18.367 ] / 4