Pulmonary function testing reference values and interpretations in pediatric training programs.

A questionnaire was sent to all pediatric training programs to evaluate the use of pulmonary function reference standards and the interpretation of pulmonary function test results. Responses were obtained from 107 of 130 institutions, and 94 of these had pulmonary function laboratories available. Of the 94, 60 used one of three reference standards. The primary reason the reference standards were chosen was either unknown or because they came with the spirometer (24), were recommended by another person or were those used in that person's training (34), or were thought to be the best standards available or most applicable to the population to be tested (31). To define abnormality, most used an 80% predicted cutoff for forced vital capacity, forced expiratory volume in 1 second, and forced expiratory flow at 25% to 75% vital capacity. For a change in an individual through time, most used a 10% change for forced vital capacity, forced expiratory volume in 1 second, and forced expiratory flow at 25% to 75% vital capacity. Thirteen used statistical methods to define abnormal individuals and none used statistical methods to define a significant change over time. Although there are a few guidelines for reference standards and interpretations of pulmonary function tests, it appears that most laboratories are not using those guidelines and that further guidelines and education are needed.