Maximal expiratory flow at FRC (V′max_FRC): Methods of selection and differences in reported values

Abstract

SummaryWe 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 HHS Public Access Author Manuscript Author ManuscriptAuthor ManuscriptAuthor Manuscript ′ 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.

Lung function in infants after repair of congenital diaphragmatic hernia

“…The C rs and R rs were the mean of at least 8 technically acceptable efforts with coefficient of variation of less than 15%. The VV maxFRC was the mean of the 3 highest recorded values [15][16][17][18][19].…”

Fluticasone Improves Pulmonary Function in Children under 2 Years Old with Risk Factors for Asthma

“…Pulmonary function tests were obtained when children met eligibility criteria, had not suffered an acute exacerbation in the last 3 weeks, and had not received any corticosteroid (inhaled or systemic) over the last month. Pulmonary function tests were assessed by the rapid thoracic-abdominal compression technique (15)(16)(17) with a SensorMedics 2600 system (Yorba Linda, CA) to obtain the maximal flow at the functional residual capacity (V maxFRC).…”

Explorations fonctionnelles respiratoires et polysomnographies chez le nourrisson et l’enfant : aspects pratiques

“…Mais du fait des modifications de la compliance thoracique avec la croissance, l'utilisation de la jaquette est difficile pour le suivi [18][19][20].…”