Pulmonary function testing in young children.

Pulmonary function testing (PFT) is of great importance in the evaluation and treatment of respiratory diseases. Spirometry is simple, noninvasive, and has been the most commonly used technique in cooperative children, obtaining reliable data in only a few minutes. The development of commercially available equipment as well as the simplification of previous techniques that now require minimal patient cooperation applied during tidal breathing have significantly stimulated the use of PFT in younger children. Tidal breathing techniques such as impulse oscillometry, gas dilution, and plethysmography have permitted previously unobtainable PFT in children 2 to 5 years of age. The purpose of this review is to help clinicians become familiar with available PFT techniques used in young children by discussing their general principles, clinical applications, and limitations.