The Science Journal of the American Association for Respiratory Care

2002 OPEN FORUM Abstracts

STANDARDIZING REFERENCE VALUES FOR PULMONARY FUNCTION TESTING IN A METROPOLITAN AREA

Tim Frymyer, BS, RRT, Kevin Hamby, CRT, David Mussetter, BA, RRT, Michael Trevino, MS, RRT, Gary Weinstein, MD, FCCP, Presbyterian Hospital of Dallas, Dallas, Texas.

BACKGROUND: Pulmonary function testing is a common practice in hospitals and physician offices across the country. Each facility may reference different sources to acquire a set of normal predicted values. The purpose of this study was to compare reference standards utilized in facilities within our metropolitan service area.

METHOD: Eighteen hospitals in the Dallas/Ft. Worth area representing 7,153 beds were surveyed. Our primary focus was on adult FVC, FEV1 and DLCO references ranges as these are the most frequent tests performed in both hospital and physician office settings. We found a variety of reference standards in use across the community of hospitals; some of which were used in combination. For spirometry, Knudson was used by 72% of the hospitals, Crapo 17%, Morris, Collins, ITS and Enright (CHS) were used by 6% of the hospitals. For DLCO, Knudson was used by 44% of the hospitals, Crapo 28%, Miller 11%, Morris, Collins, Burrows, and Polgar were used by 6% of the hospitals. We compared predicted values between different reference standards in a 40 & 70 y/o, Caucasian and African-American male each weighing 150 pounds at 67? tall. For FVC and FEV1 the American Thoracic Society (ATS) guidelines defines variance as >200ml?s between FVCs and FEV1s during a spirometry test.

RESULTS: Variance in predicted values is listed in the table below. We compared what our institution uses (Knudson and Miller) against Crapo, the second most used standard in our survey.

  Knudson Crapo Diff. ml’s Miller Crapo Difference ml/min/mmHG
40 y/o
Cauc. male
FVC=4.39 FVC=4.70 310 DLCO=31.76 DLCO=35.69 3.93 (12.4%)
FEV1=3.63 FEV1=3.88 250
40 y/o
Black male
FVC=3.73 FVC=4.00 270 DLCO=26.99 DLCO=30.34 3.35 (12.4%)
FEV1=3.09 FEV1=3.30 210
70 y/o
Cauc. male
FVC=3.50 FVC=4.06 560 DLCO=24.89 DLCO=29.12 4.23 (17.0%)
FEV1=2.76 FEV1=3.15 390
70 y/o
Black male
FVC=2.97 FVC=3.45 480 DLCO=21.15 DLCO=24.76 3.61 (17.0%)
FEV1=2.34 FEV1=2.68 340

CONCLUSION: Due to the significant variances reflected above, care should be taken when interpreting both the volume change, as well as the percent change of parameters evaluated. Additionally, an opportunity may exist to establish a community benchmark for reference standards utilized in the assessment of spirometry and diffusion for hospital and physician office- based practices.

OF-02-117

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