What are the four stages of COPD?
1. Mild COPD: This stage has an FEV1 of about 80% or above normal.
2. Moderate COPD: It has an FEV1 ranging from 50-80% of normal
3. Severe COPD- It is characterized by severe emphysema and has an FEV1 ranging from 30-50% of normal.
4. Severe COPD; It is very critical and the last stage. FEV1, lower than stage 3, characterize it.