Functional Residual Capacity in Healthy Preschool Children Lying Supine^1,2

Abstract

IntroductionDetermination of normal values for many aspects of lung function in preschool children is often difficult since they do not readily comprehend instructions for pulmonary function testing and can be uncooperative. One basic aspect of lung function that can be measured in anesthetized (1) and in awake cooperative preschool children (2) is FRC. Normal values have been derived for sitting and standing subjects (2-4). However, these studies may not be applicable to supine children, as the FRC is known to decrease when assuming the supine position (2, 3, 5). In order to evaluate FRC measurements made on ill children, who are usually nursed in the supine position, reference values for healthy children lying supine are necessary. Reference values have been published for healthy children younger than 3 yr of age (2,6) and older than 6 yr (7) while recumbent. However, FRC values for healthy, supine children between the ages of 3 to 6 yr are not available, and extrapolation from data available for younger or older children to this age group may not be valid in view of the nonlinear relationship between lung volumes and height, age, or weight (3). We therefore measured FRC in healthy supine children, including those 3 to 6 yr of age, with and without anesthesia, in order to establish reference values and to examine normal lung growth in preschool children.

Estimation of lung growth using computed tomography

“…Therefore, in this study, lung volume was measured on the scans and this volume was related to the predicted values for FRC. The technique used to make the prediction equations is different for the children aged v6 yrs [10] compared to the older children [11]. BAR-YISHAY et al [10] measured FRC in the supine position, ZAPLETAL et al [11] measured FRC in the sitting position.…”

“…The technique used to make the prediction equations is different for the children aged v6 yrs [10] compared to the older children [11]. BAR-YISHAY et al [10] measured FRC in the supine position, ZAPLETAL et al [11] measured FRC in the sitting position. This results in higher values for FRC in the older children.…”

“…CT-determined gas volume was compared to predicted normal values for functional residual capacity (FRC) using equations for children of various body lengths. FRC was measured in the supine position in children aged 0-6 yrs [10] and in the sitting position in the children aged o6 yrs [11]. CT-determined gas volume was also compared to published values of total lung capacity (TLC) for children with a body length v115 cm [3] and to predicted values for children with a body length w115 cm [11].…”

Age and the onset of desaturation in apnoeic children

“…The FRC in children correlates well with height, weight, and age; but there is no difference in FRC between the sexes.4-6 The ratio of FRC to body weight increases with age. [4][5][6] reported that the ratio of FRC to body weight was 17 5:4 ml-kg -I in infants and 24 + 6 ml-kg -I in children more than one year of age. Oxygen consumption is relatively greater in younger than in older children.…”

Computed tomographic estimation of lung dimensions throughout the growth period

“…The CT-determined gas volume was compared with predicted normal values for functional residual capacity and TLC using standard prediction equations based on body length [1,4,[43][44][45]. CT-calculated lung expansion was compared between males and females.…”