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Maximal expiratory flow at FRC (V′max FRC ): Methods of selection and differences in reported values
Author(s) -
Koumbourlis Anastassios C.,
Chen Xin C.,
Rao J. Sunil,
Schluchter Mark D.,
Easley Kirk,
Colin Andrew A.,
Hiatt Peter,
Kattan Meyer,
McCarthy Kevin,
Mellins Robert B.,
Peavy Hannah,
Platzker Arnold C.G.,
Steinbach Suzanne,
Ting Andrew,
Weisner Michael D.,
Wohl Mary Ellen B.
Publication year - 2004
Publication title -
pediatric pulmonology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.866
H-Index - 106
eISSN - 1099-0496
pISSN - 8755-6863
DOI - 10.1002/ppul.10452
Subject(s) - medicine , functional residual capacity , asymptomatic , residual volume , limits of agreement , lung volumes , nuclear medicine , lung
We compared three methods of reporting maximal expiratory flow (V′max FRC ) measured in partial expiratory flow‐volume curves (PEFVCs) at the point of functional residual capacity (FRC). PEFVCs were obtained with the rapid thoracoabdominal compression technique (RTC) on a total of 446 occasions in 281 HIV‐negative, asymptomatic infants (4.8–28.1 months old). Three different expressions of V′max FRC were recorded: 1) the highest measured flow (maxV′ FRC ), 2) the mean of the three highest flows (mean3V′ FRC ), and 3) the flow at FRC in a composite curve (compV′ FRC ) consisting of PEFVCs, obtained at different jacket pressures and superimposed at their distal limb. The numerical value of maxV′ FRC was 7.4% (±5.6%) higher than the mean3V′ FRC , and 11.9% (±17.7%) higher than the compV′ FRC ; the mean3V′ FRC was 5% (±18.3%) higher than the compV′ FRC . Bland‐Altman analysis was used to evaluate the agreement between the three indices. The mean difference and 95% limits of agreement were: maxV′ FRC −mean3V′ FRC , 14 ± 18 ml/sec; maxV′ FRC − compV′ FRC , 23 ± 58 ml/sec; and mean3V′ FRC − compV′ FRC , 10 ± 52 ml/sec. The differences between the slopes of the three indices (regressed against height) were statistically significant, although clinically unimportant. We conclude that despite their high correlation, the mean3V′ FRC and maxV′ FRC should not be used interchangeably, and that the composite analysis, although useful, does not improve the reproducibility of V′max FRC , and thus it cannot be recommended for routine use in its current form. Pediatr Pulmonol. 2004; 37:318–323. © 2004 Wiely‐Liss, Inc.