TY - JOUR
T1 - Effect of effort on measurement of forced expiratory volume in one second
AU - Krowka, M. J.
AU - Enright, P. L.
AU - Rodarte, J. R.
AU - Hyatt, R. E.
N1 - Copyright:
Copyright 2017 Elsevier B.V., All rights reserved.
PY - 1987
Y1 - 1987
N2 - The American Thoracic Society recommends that the largest FEV1 be reported from a set of forced expiratory vital capacity maneuvers performed with maximal expiratory effort. However, increased expiratory effort can decrease the FEV1. When we evaluated the peak expiratory flow rate (PEFR) in 5 normal subjects, measured from flow-volume curves, as a noninvasive index of expiratory effort, it was positively correlated with indices of effort obtained by using an esophageal balloon. We then measured the difference (dFEV1) between the largest FEV1 and the FEV1 from the maneuver with the highest PEFR during 10 test sessions in 10 normal subjects. Thus, dFEV1 was always ≥ 0. The mean dFEV1 was 110 ml for all sessions but decreased to 80 ml when maneuvers with poorly reproducible PEFR or forced expiratory vital capacity values were discarded. We also reviewed 9,471 spirometry sessions from outpatients and found dFEV1 to be greater than 50 ml in 26% of this population and greater than 151 ml in 7%. We concluded that during standard spirometry, FEV1 is inversely dependent on effort. Maximal effort decreases FEV1 because of the effect of thoracic gas compression on lung volume. We recommend that values from spirometry maneuvers that demonstrate submaximal effort, indicated by a decreased PEFR, be discarded. The flow-volume curve display of superimposed efforts facilitates the recognition of submaximal efforts.
AB - The American Thoracic Society recommends that the largest FEV1 be reported from a set of forced expiratory vital capacity maneuvers performed with maximal expiratory effort. However, increased expiratory effort can decrease the FEV1. When we evaluated the peak expiratory flow rate (PEFR) in 5 normal subjects, measured from flow-volume curves, as a noninvasive index of expiratory effort, it was positively correlated with indices of effort obtained by using an esophageal balloon. We then measured the difference (dFEV1) between the largest FEV1 and the FEV1 from the maneuver with the highest PEFR during 10 test sessions in 10 normal subjects. Thus, dFEV1 was always ≥ 0. The mean dFEV1 was 110 ml for all sessions but decreased to 80 ml when maneuvers with poorly reproducible PEFR or forced expiratory vital capacity values were discarded. We also reviewed 9,471 spirometry sessions from outpatients and found dFEV1 to be greater than 50 ml in 26% of this population and greater than 151 ml in 7%. We concluded that during standard spirometry, FEV1 is inversely dependent on effort. Maximal effort decreases FEV1 because of the effect of thoracic gas compression on lung volume. We recommend that values from spirometry maneuvers that demonstrate submaximal effort, indicated by a decreased PEFR, be discarded. The flow-volume curve display of superimposed efforts facilitates the recognition of submaximal efforts.
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U2 - 10.1164/ajrccm/136.4.829
DO - 10.1164/ajrccm/136.4.829
M3 - Article
C2 - 3662235
AN - SCOPUS:0023581676
SN - 0003-0805
VL - 136
SP - 829
EP - 833
JO - American Review of Respiratory Disease
JF - American Review of Respiratory Disease
IS - 4
ER -