Forced Expiratory Flows and Volumes in Infants

Abstract

Forced expiratory flows (FEF) can be measured in infants from lung volumes initiated near total lung capacity. In order to establish reference values and to evaluate lung growth, we obtained measurements in 155 healthy subjects between 3 and 149 wk of age. Forced vital capacity (FVC) was highly correlated with body length; however, after accounting for length, age was also significant. When subjects were divided at the median age (40 wk) younger compared with older subjects had a significantly larger slope for length (3.7 versus 2.8; p = 0.002). The flow parameters (FEF(50), FEF(75), FEF(85), and FEF(25-75)) were highly correlated with length, and those infants whose mothers smoked had lower flows. For FEF(75), male subjects had lower flows than female subjects. The relationship between FEF and volume was assessed using FEV(0.5)/FVC, which decreased with increasing length. Smaller subjects emptied their lung volume proportionately faster. We conclude that our study provides reference values for this age group and demonstrates that smoke-exposed infants and male subjects have decreased FEF. In addition, our findings indicate that lung volume increases most rapidly during the first year of life and that airways are large relative to lung volume very early in life.

New reference equations to improve interpretation of infant lung function

“…9,11,12 Had we relied on expressing data as weight-corrected values, the current results would be similar to those previously reported for FRC p , 26 and C rs 7,8 but higher than those reported for V T by Fuchs et al 15 when using an ultrasonic flowmeter in a large population of unsedated newborns studied during the first 8 weeks of life. In contrast to previous observations, 7,8,15 after adjustment for body size, significant sex differences were only noted for FRC p , with boys tending to have slightly higher values, a difference that increased with age, and which was therefore adjusted for by including an interaction term in the equation.…”

“…[37][38][39] We have recently demonstrated marked equipment differences in predicted values for parameters of forced expired volumes and flows derived from the rapid thoraco-abdominal compression technique and provided an interim solution for investigators using the Jaeger BabyBody device. 13 In contrast to the outcomes investigated in the current study, forced flows and volumes are known to be influenced by the sex of the infant, 11,12 thereby requiring larger numbers of individuals before reliable reference equations can be developed independently for the Jaeger equipment. Similarly, although equations were formulated for C rs and R rs , these were based on only 105 sets of results, which may be insufficient to create reliable reference equations.…”

“…This has rarely been done due to the specialized and time-consuming nature of IPF tests and the need for sedation beyond the first few weeks of life. While some reference values have been published previously, [7][8][9][10][11][12] these were frequently derived using custom-built equipment (which may no longer be appropriate when interpreting results collected using current, commercially available equipment 13,14 ) or only encompass a narrow age range. 15 With increasing use of modern IPF devices, there is an urgent need for appropriate equipment-specific normative data that encompass the entire age range over which such measurements are made (generally 0-2 years).…”

Early detection of cystic fibrosis lung disease: multiple-breath washout versus raised volume tests

“…25 26 All RVRTC measurements and analyses were undertaken according to current guidelines and recommendations. 9 Despite using slightly different equipment and software from that reported previously, the healthy infants had RVRTC results similar to those predicted 26 and to those we have reported previously. 11 Currently available data are insufficient to calculate accurate prediction equations or Z scores for LCI during infancy.…”

“…9 Z scores for FEV 0.5 , FEF 75 , FEF and FVC were calculated from published equations. 26 A Z score ,-1.96 (below the 2.5th centile) was defined as diminished airway function.…”