WHAT IS OBSTRUCTIVE LUNG DISEASE?
Asthma, chronic bronchitis, and emphysema are examples of obstructive lung disease. Characteristic of this group is difficulty getting all the air out. As a group obstructive lung diseases are the greatest cause of respiratory morbidity in the United States. Obstructive lung disease is best diagnosed by a simple pulmonary function test of the forced vital capacity (see Section I). As shown in Figure 1, the obstructed patient can take a deep breath but the rate of exhalation is slowed. This is contrasted with a restricted patient, who cannot inhale as much air but can exhale it readily. For comparison the normal FVC curve is also shown.
