Question

In patients with a post-bronchodilator FEV1/FVC < 0.70, at what post-bronchodilator FEV1 predicted value is the COPD severity classified as Stage 3 or 'severe'?

Answer 1

COPD is classified as Stage 3 or 'severe' when the post-bronchodilator FEV1 predicted value is between 30% and 49% after a patient shows a post-bronchodilator FEV1/FVC ratio of less than 0.70.

Step-by-step explanation:

The severity of chronic obstructive pulmonary disease (COPD) is classified based on the post-bronchodilator forced expiratory volume in one second (FEV1) expressed as a percentage of the predicted value. When patients have a post-bronchodilator FEV1/FVC ratio of less than 0.70, indicating the presence of airflow limitation, the severity of COPD can then be further staged based on their FEV1. For COPD to be classified as Stage 3, which is considered 'severe', the post-bronchodilator FEV1 predicted value must be between 30% and 49% of the predicted normal value for the patient.