Forced expiratory manoeuvres in children: do they meet ATS and ERS criteria for spirometry?

The aim of this study was to evaluate the applicability of American Thoracic Society and European Respiratory Society criteria for spirometry in children. Maximal expiratory flow/volume (MEFV) measurements from 446 school-age children, experienced in performing MEFV manoeuvres, were studied and acceptability (start-of-test (backward extrapolated volume as a percentage of forced vital capacity (FVC) ([Vbc%FVC) or as an absolute value (Vbe), end-of-test (forced expiratory time (FET)) and reproducibility criteria (absolute and percentage difference between best and second-best FVC and forced expiratory volume in one second (FEV1) (deltaFVC, deltaFVC %, deltaFEV1 and deltaFEV1 %)) were applied to these manoeuvres. The Vbe%FVC criterion was met by 91.5%, the Vbe <0.15 L criterion by 94.8% and the Vbe <0.10 L by 60.1% of children. Vbe <0.15 L appeared to be a more useful parameter than Vbe%FVC. The FET criterion was met by only 15.3% of children. deltaFVC <0.2 L and deltaFEV1 <0.2 L were met by 97.1% and 98.4%, and deltaFVC <0.1 L and deltaFEV1 <0.1 L by 79.8% and 84.3% of the children, respectively. These criteria appeared to be less useful compared to percentage criteria (deltaFVC % and deltaFEV1 %). Even experienced children did not meet all international criteria for spirometry. However, most of their MEFV curves are useful for interpretation. Based on the performance of these children, a re-evaluation of criteria for maximal expiratory flow/volume measurements in children is proposed.