Spirometry.

Spirometry is the most widely used pulmonary function test. It is used for diagnosis and monitoring in a wide variety of obstructive and restrictive disease patterns. Spirometry is the primary measure in determining disability due to pulmonary disease, and is widely applied in the evaluation of bronchodilator response and airway hyperreactivity. A wide variety of spirometry equipment is currently available, from small portable units to large laboratory systems capable of multiple functions. Most spirometers rely heavily on computerization, which makes them easy to use, but require training and experience on the part of the user. Valid spirometry demands equipment that conforms to recommended standards, and performance of the tests to meet criteria for acceptability and reproducibility. Interpretation of spirometry requires attention to these standards and to careful selection of reference values.