Using spirometry in the primary care office. A guide to technique and interpretation of results.

Spirometry is important in evaluating patients with respiratory complaints and helpful in following the course of disease. The American Thoracic Society encourages office use of spirometry and has published guidelines and minimum standards to promote accurate and appropriate testing. Equipment designed to meet these standards is available for office use, and peak flowmeters are available for home use by selected patients. When performed correctly and interpreted in the context of other clinical data, spirometry may identify reductions in flow (obstruction) or volume (restriction). Characteristics of the flow-volume loop may suggest specific types of upper or large airways obstruction. Serial monitoring of forced expiratory volume in 1 second in chronic obstructive pulmonary disease and of peak expiratory flow rate in asthma may help guide medical therapy. When spirometry fails to detect or completely characterize impairment of lung function, more extensive testing in a pulmonary function laboratory is indicated.