Fractionating respiratory resistance in young children

Abstract
Total respiratory resistance (Rrs) and the fraction of this resistance located peripherally, (Fp) were measured in a group of children (3-5 yr old). The technique used forced random noise to characterize the frequency dependence of effective resistance and an algorithm to compute Rrs and Fp from these data. The overall mean value .+-. SD for Fp was 0.534 .+-. 0.070; the mean value of 0.464 for the 6 children near 5 yr of age was significantly different (P < 0.001) from the mean value of 0.576 found in the younger children. The overall mean value .+-. SD for Rrs was 16.9 .+-. 5.8 cmH2O .cntdot. l-1 .cntdot. s; individual values appeared to be correlated with height. These results agree with previous reports indicating that children have a larger fraction of respiratory resistance in the periphery than do adults.