FUNCTIONAL RESIDUAL CAPACITY IN HEALTHY PRESCHOOL-CHILDREN

The purpose of this study was to evaluate the feasibility of routine f unctional residual capacity (FRC) measurements in healthy preschool ch ildren aged 2.7-6.4 yrs. Furthermore, accuracy and reproducibility wer e investigated A mass-produced closed-circuit helium dilution device ( rolling seal) was used. Selection of the 113 healthy children (from th e 571 measured) was based on an extensive personal and family history questionnaire and on clinical examination before measurements were per formed. With three successive attempts it was possible to achieve at l east two reproducible measurements in 73% of the children (repeatabili ty coefficient 95.3 mt). The main problems were leakage at the corner of the mouth and irregular breathing pattern. The mean time to perform a measurement was 113 s. Mean FRC was significantly higher in boys th an in girls: 778 versus 739 mL for a body length of 110 cm (p<0.05). F RC correlated with height (H) (r=0.69), weight (W) (r=0.56), age (A) ( r=0.62) and all three combined (r=0.70): FRC = -534.89 + 1.84 x W (kg) + 10.07 x H (cm) + 2.51 x A (months). When a power or exponential fun ction was used to describe FRC as a function of height, the results we re not superior to the linear regression (r=0.69): FRC (mL) = -766.2 13.8 x H (cm) (r=0.69) or FRC (L) = 0.620 x H (m)(2.03) (r=0.69) or F RC (mL) = 99.5 x e(0.018xH) (cm) (r=0.69). Among these, we recommend t he power function because it will better fit broader height ranges. Re liable functional residual capacity measurements can be routinely perf ormed in preschool children with a mass-produced device, Reference val ues were collected for children 95-125 cm in height.