Spirometry in children aged 3 to 5 years: reliability of forced expiratory maneuvers.

The aim of this study was to evaluate the feasibility and reproducibility of forced expiratory maneuvers during standard spirometric evaluation in preschool children. Among 570 young children attending our laboratory, we retrospectively selected 355 patients (14% 3-4-year-olds, 48% 4-5-year-olds, and 38% 5-6-year-olds) who carried out spirometric tests for the first time. The indications for such tests were history of asthma (70%), followed by chronic cough (20%) and other miscellaneous conditions (10%). Eighty-eight, 175, and 92 children performed one, two, and three acceptable tests respectively. Forced expired volume in 1 sec (FEV(1)) and forced vital capacity (FVC) did not differ significantly between attempts in children performing either two or three attempts. Forced expiratory time (FET), i.e., the total time required for the forced expiratory maneuver, was 1.7 +/- 0.1 sec (mean +/- SEM), and was no greater than 1 sec in 21.3% of all tested children. Consequently, FEV(1) does not appear to be well-suited to this age group. Forced expiratory volume in 0.50 and 0.75 sec (FEV(0.5), FEV(0.75)) were thus measured in the group of children performing three attempts (n = 92), and there was no statistical difference between attempts. In 267 children performing two or three tests, the ATS criteria of reproducing FEV(1) and FVC within <or= 0.1 L seemed to be preferable in this young population. Indeed, more than 70% of the tested children presented their two best efforts (FVC and FEV(1)) not varying by more than 0.1 L. Individual coefficients of variation (CV = SD/mean x 100%) over three tests for FEV(1) and FVC were 6.71 +/- 0.53% and 6.35 +/- 0.41% (mean +/- SEM), respectively. These results show that forced expiratory tests are not always feasible in young children, but that 55% (196/355) of our selected population performed reliable maneuvers (at least two FVC and FEV(1) reproducible within 0.1 L), provided that they were supervised by a carefully trained pediatric medical staff. Copyright 2001 Wiley-Liss, Inc.