Respiratory function testing in children

Some practical aspects of respiratory function testing (RFT) are reviewed w ith special interest on applications in preschool children. RFT may be used for diagnostic, management and follow up purposes. Children may benefit fr om RFT in a variety of pathological situations. Asthma and other obstructiv e airways diseases certainly represent the most frequent conditions. Vital Capacity and Forced Expiratory Volume in one second (FEVI) may usually be o btained from age 7 on. In smaller children, the forced expiratory manoeuvre is much less successful. Non invasive measurements such as respiratory res istance (Rrs) or specific airway resistance (sRaw) may be used. Rrs is usua lly measured by the interrupter technique or the forced oscillation techniq ue and sRaw by body plethysmography, not requiring the estimation of thorac ic gas volume. Because much variability is introduced by the upper airways, these parameters are less suited than FEVI to establish the degree of base line airway obstruction. On the other hand, Rrs and sRaw may quantify rever sibility of airway obstruction and/or bronchial hyperresponsiveness. Lung h yperinflation may be identified by the assessment of Functional Residual Ca pacity (FRC) with a dilution method. More generally lung growth may be foll owed up in longitudinal studies of FRC even in small children. More work is needed to standardize RFT techniques and indications in the preschool chil d.