RT Journal Article SR Electronic T1 The Physiologic Basis of Spirometry JF Respiratory Care FD American Association for Respiratory Care SP 1717 OP 1726 VO 54 IS 12 A1 Don Hayes, Jr A1 Steve S Kraman YR 2009 UL http://rc.rcjournal.com/content/54/12/1717.abstract AB Spirometry is the most useful and commonly available tests of pulmonary function. It is a physiological test that measures individual inhalation and exhalation volumes of air as a function of time. Pulmonologists and general-practice physicians commonly use spirometry in their offices in the assessment and management of lung disease. Spirometric indices are well validated and easily interpreted by comparison with established normal values. The remarkable reproducibility of spirometry results from the presence of compliant intrathoracic airways that act as air flow regulators during forced expiration. Because of this anatomic arrangement, expiratory flow becomes dependent solely on the elasticity of the lungs and airway resistance once a certain degree of expiratory force is exerted. Insight into this aspect of respiratory physiology can help in the interpretation of spirometry.