FRC measurements using body plethysmography in young children.

BACKGROUND: Measurement of FRC in whole body plethysmography (FRCpleth) is not performed in young children (aged 3-5 years) because it involves sitting alone in a closed box and breathing attempts against occlusion.

OBJECTIVE: To assess the feasibility of measuring FRCpleth in young children.

METHODS AND RESULTS: Seventy-one of 102 children (age range 3.3-6.9 years) performed spirometry and FRCpleth measurements. Twenty-six children had controlled asthma (Group-A); 26 children were tested during asthma exacerbation had uncontrolled asthma (Group-UA), and 19 children were tested after receiving chemotherapy treatment (Group-C). Tests according to adult recommendations were first taught outside the plethysmograph and then performed with minor technical adaptations. Each test included two consecutive FRC measurements obtained during 2-3 sec of occlusion. Total lung capacity (TLC) and residual volume (RV) were calculated. Values were compared to FRC measured by Helium-dilution (FRC-He) in healthy preschool children and to extrapolated FRCpleth values of school children, and between the groups.

RESULTS: Group-A showed normal spirometry and normal TLC values, with mildly elevated FRCpleth and RV values (125 +/- 20 and 153 +/- 33 %predicted, respectively; P < 0.0001 for both values). Group-UA showed obstructed flows combined with high FRCpleth and RV (146 +/- 26 and 189 +/- 38 %predicted; P < 0.0001) and normal TLC. Group-C showed a restrictive spirometry pattern combined with lower than normal TLC (86 +/- 15 %predicted; P < 0.0251).

CONCLUSIONS: Measuring absolute lung volumes by plethysmography in young children is feasible and can detect abnormal lung volumes. It is essential to study a larger group of healthy children for reference values and to allow for standardization of the procedure.