The Science Journal of the American Association for Respiratory Care

2008 OPEN FORUM Abstracts

SELECTION OF REFERENCE EQUATIONS FOR ADULT PULMONARY FUNCTION TESTS: AN AARC DIAGNOSTICS SECTION SURVEY

Charles McArthur1, Gregg Ruppel2



Background: The 2005 ATS/ERS standards for lung function testing recommend a reference equation for spirometry but fail to make a recommendation of reference equations for lung volume and diffusing capacity measurements.

Methods:
During the third quarter of 2007, the members of the AARC diagnostics section list serve were asked to complete a survey of the reference equations used in their institutions via an online survey tool. We asked that only one member per facility respond to the survey.

Results:
There were 154 responses from the 202 member list serve. One hundred twelve (73%) respondents reported using a spirometry reference equation other than that recommended by the 2005 ATS/ERS standards. The most frequently used reference equations for spirometry, lung volume, and diffusing capacity measurements are shown below.
Selection of reference sets was primarily the preference of the medical director for spirometry, lung volumes, and DLCO equations. Race correction for lung volumes (TLC, etc.) was performed in only 42.1% of respondents' laboratories. Classification of normal vs. abnormal was based on % predicted in 72.9% of labs, upper/lower limit of normal (ULN/LLN) in 23.2%, and 3.9% used some other methodology.

Conclusion:
1. The majority of members surveyed report that their institutions have not adopted the ATS/ERS recommendation of standard reference equations for spirometry.
2. There is considerable variation in the choice of reference equations for pulmonary function among the AARC diagnostic section members surveyed.
3. The majority of laboratories surveyed use % predicted for interpretive purposes rather than LLN as recommended by ATS/ERS.
4. Less than half of respondents currently use race correction for lung volume predicted values.