One of the most useful instruments for office practice is the spirometer. Today, the spirometer must find its rightful place alongside the sphygmomanometer, the electrocardiograph, and the ophthalmoscope. Abnormal spirometry is an indicator of increased risk for premature death from all causes. This indication has been known since the time of its invention in 1846 by John Hutchinson, a surgeon.<sup>21 Hutchinson J. On the capacity of the lungs, and on the respiratory functions, with a view of establishing a precise and easy method of detecting disease by the spirometer Medico-Chirurgical Transactions (London) 1846 ;  29 : 137-161

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Why has spirometry been so slow to be accepted in the mainstream of clinical practice? The author believes that spirometry has been couched in too much mystique. It also has required the careful study of structure– function relationships of the human lung to understand what causes alterations in spirometric measurements. Longitudinal studies have helped clarify the clinical significance of tests purported to indicate early stages of chronic obstructive pulmonary disease (COPD). Also, in the past, inexpensive and user-friendly devices were not available for office and clinic use. All of this is changing rapidly. Now the primary care physician and his or her assistant can learn the basics of spirometry easily, which provides two main values—the forced vital capacity (FVC) and the forced expiratory volume in 1 second (FEV₁). Reviewing how these values can be applied immediately to everyday practice is the purpose of this article.