• Assess the differences between flow and volume responses after bronchodilator reversibility testing in patients over different clinical chronic obstructive pulmonary disease stages (GOLD stage I to GOLD stage IV).
• Study the Correlation between the bronchodilator response and the severity of the disease.

chronic obstructive pulmonary disease is a common preventable and treatable disease characterized by persistent airflow limitation that is usually progressive. The diagnosis requires an evidence of obstructive pattern by spirometry measured before and after bronchodilators.

The degree of reversibility of airflow obstruction differs between patients, and does not predict the response to bronchodilator therapy. It can be seen in terms of forced vital capacity (FVC) or forced expiratory volume in the first second (FEV1),or Inspiratory capacity (IC) or residual volume (RV).

Inclusion Criteria:

• Patients Clinical diagnosis of Chronic Obstructive Pulmonary Disease
• Must be able to do pulmonary function test
• Age more than 40 years
• Stable Chronic Obstructive Pulmonary Disease patients

Exclusion Criteria:

Any patients with a diagnosis of:

• Bronchial asthma
• Bronchiectasis
• Respiratory failure
• Decompensated core pulmonale
• Chronic Obstructive Pulmonary Disease combined with any other respiratory disease