ATS Pulmonary Function Laboratory Manual

ATS Pulmonary Function Laboratory Management & Procedure Manual | 3rd Edition

APPENDIX 12.3  Calculation of Percent Change in Lung Function Calculation of percent change in lung function (e.g., FEV 1

) is accomplished by using the highest value associated

with a specific dose.

− highest post-methacholine FEV 1

% change = highest post-diluent FEV 1

× 100

highest post-diluent FEV 1

Example calculation of percent change between the post-diluent FEV 1 FEV 1 , using the highest value from three FVC test maneuvers at each stage.

and the starting dose of methacholine

1

2

3

Baseline FEV 1

(L)

3.20 3.27 2.94

3.24 3.24 2.98

3.30 3.29 3.03

(L)

Post-diluent FEV 1 Post-dose FEV 1 (L)

% change = ( 3 . 29 − 3 . 03 ) /3 . 29 % change = decrease of 7 . 9 %

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