Spirometric Classification
The normal lung function, when measured with Spirometry, diminishes approximately 5% every 10 years after age 35 years old. Therefore, it is rare for a person over 35 to have a “100%” In addition, the normal values for the FVC and FEV (2 of the measurements in a pulmonary function test) vary depending on age, height, sex and race. The numbers are higher for:
- 35 years old vs 65 years old
- Taller than shorter builds
- Men than women
- Caucasian than most other races.
The number used (FEV1) is a percent of the average expected of someone of your height, age, sex and race. It is expressed as a percent of predicted. Any number over 80% is considered normal
| STAGE |
| Symptoms | Pulmonary Function Tests (PFT) with an FEV1 result of: |
| STAGE I | mild | Often minimal shortness of breath with or without cough and/or sputum. Usually goes unrecognized that lung function is abnormal | > 80% of predicted |
| STAGE II | moderate | Often moderate or severe shortness of breath on exertion, with or without cough, sputum or dyspnea. Often the first stage at which medical attention is sought due to chronic respiratory symptoms or an exacerbation | 50-80% of predicted |
| STAGE III | severe | more severe shortness of breath, with or without cough, sputum or dyspnea - often with repeated exacerbations which usually impact quality of life, reduced exercise capacity, fatigue | 30 – 50% of predicted |
| STAGE IV | very severe | appreciably impaired quality of life due to shortness of breath - possible exacerbations which may even be life threatening at times | Less than 30% of predicted -- |
| The above chart is based in part on the Global Initiative for Chronic Obstructive Lung Disease. |
