|
Stages of COPD
The basic "standard" for evaluating the
severity of COPD has primarily been spirometry, also known as the Pulminary
Function Test (PFT).
However, functional dyspnea, body
mass index (BMI), and FEV1 from Spirometry, when evaluated
collectively, offer better insight into outcomes such as survival.
Most times, the spirometry results are the only referenced statistics.
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
--
or less than 50% with chronic
respiratory failure |
The above chart is
based in part on the Global Initiative for Chronic Obstructive Lung
Disease. Functional dyspnea
As assessed by the Medical Research Council dyspnea scale.
0: not troubled with breathlessness except with strenuous exercise.
1: troubled by shortness of breath when hurrying or walking up a
slight hill.
2: walks slower than people of the same age due to breathlessness
or
has to stop for breath when walking at own pace on the level.
3: stops for breath after walking ~100 m or after a few minutes on the
level.
4: too breathless to leave the house or breathless when dressing
or
undressing.
BMI is easily obtained by dividing the weight (in kg) over the
height (in m²). Values less than 21 kg•m-2 are associated
with increased mortality. Note: The words dyspnea and
dyspnoea are often interchanged. |
