Chronic obstructive pulmonary disease study of choice

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief:

Overview

The diagnosis of COPD is confirmed by spirometry, a test that measures the forced expiratory volume in one second (FEV₁), which is the greatest volume of air that can be breathed out in the first second of a large breath. Spirometry also measures the forced vital capacity (FVC), which is the greatest volume of air that can be breathed out in a whole large breath. Normally, at least 70% of the FVC comes out in the first second (i.e. the FEV₁/FVC ratio is >70%). A ratio less than normal defines the patient as having COPD. Six minute walk tests act as an predictor of mortality in patients with moderate COPD (patients who desaturate have worse mortality compared with those who don't desaturate.)

Diagnostic Study of Choice

Pulmonary Function Test / Spirometry

• Many patients labeled as having airway obstruction do not have obstruction when tested.
• COPD is particularly characterized if a ratio of forced expiratory volume over 1 second (FEV₁) to forced vital capacity (FVC) being < 0.7 and the FEV₁ < 70% of the predicted value when compared with a matched control. , (see Spirometry).

• Normally, at least 70% of the FVC comes out in the first second (i.e. the FEV₁/FVC ratio is >70%). A ratio less than normal defines the patient as having COPD.
• More specifically, the diagnosis of COPD is made when the FEV₁/FVC ratio is <70%.
• The GOLD criteria also require that values are after bronchodilator medication has been given to make the diagnosis,
• The NICE criteria also require FEV1%.
• According to the ERS criteria, it is FEV1% predicted that defines when a patient has COPD, that is, when FEV1% predicted is < 88% for men, or < 89% for women.
• Spirometry can help to determine the severity of COPD.
• The FEV₁ (measured after bronchodilator medication) is expressed as a percentage of a predicted "normal" value based on a person's age, gender, height and weight:
• The severity of COPD also depends on the severity of dyspnea and exercise limitation. These and other factors can be combined with spirometry results to obtain a COPD severity score that takes multiple dimensions of the disease into account.