Spirometry for the diagnosis and management of chronic obstructive pulmonary disease

Spirometric testing is one of the oldest clinical tests still in use today. It is a straightforward test that has the patient maximally exhale from total lung capacity. The key measurements are the forced expiratory volume in the first second (FEV(1)) and the maximum exhaled volume (vital capacity [VC]). Spirometric testing utility, however, depends heavily upon the quality of equipment, the patient cooperation, and the skill of the technician performing the test. Spirometry should thus be considered a medical test and not simply a vital sign that can be performed by minimally trained personnel. In obstructive lung diseases such as chronic obstructive pulmonary disease (COPD), the characteristic changes in spirometry are a reduction in the FEV(1) with respect to the vital capacity (FEV(1)/VC ratio). Using this measurement can diagnose the presence and severity of airway obstruction. This can be used to guide therapies and predict outcomes. Using spirometry to screen for obstructive lung disease, however, can be problematic, and the effect of screening on outcomes has yet to be demonstrated.