RESUMO
Objective To investigate the distribution of measured value and the expected value of spirometry parameters in healthy children aged 5-14 years old in Beijing,and to provide evidence for clinical interpretation precisely.Methods Four hundred healthy children (198 boys and 202 girls) aged 5 to 14 years from the kindergartens and the primary schools in Beijing were selected as subjects.All of the parameters were measured by using Jaeger Masterscreen spirometry machine(Germany).Pulmonary function parameters including forced vital capacity(FVC),forced expiatory volume in 1 second (FEV1),FEV1/FVC,peak expiratory flow(PEF),forced expiratory flow at 50% of vital capacity(FEF50),forced expiratory flow at 75% of vital capacity(FEF75),and the maximal midexpiratory flow(MMEF) were collected for analysis.The expected values of the 7 parameters above were calculated according to Zapletal prediction equations(4-18 years old).The measured value vs.the expected value was calculated.Results Children aged 5 to 12 years had similar height and weight between boys and girls,and the differences were not significant(all P>0.05);while boys were taller and heavier than girls in 13-<14 years old group and 14 years old group,and the diffe-rences were significant(t=3.35,2.05,5.99,2.67;all P<0.05).The mean measured value vs.the expected value of PEF,FVC,FEV1,FEV1/FVC of children in different gender and age groups ranged between 105.0%-114.7%,95.4%-106.8%,104.6%-115.4% and 105.8%-112.6%,respectively.The mean measured value vs.the expected value of small airway function parameters FEF50,FEF75,MMEF was as follows respectively:79.7%-103.7%,70.2%-110.5%,and 81.6%-114.7%.The low limit of normal(LLN) measured value vs.the expected value of the 7 pulmonary function parameters was as follows:PEF 85.0%,FVC 84.7%,FEV1 92.4%,FEV1/FVC 98.4%,FEF50 67.7%,FEF75 60.1%,and MMEF 71.0%.Conclusions The pulmonary function parameters of the healthy children in Beijing are higher than those of the Zapletal prediction.The measured value vs.the expected value of FEV1 92.4%,FEV1/FVC 98.4%,PEF 85.0%,FVC 84.7%,FEF50 67.7%,FEF75 60.1%,and MMEF 71.0% can be used as LLN in 5-14 years old children.