以225名健康儿童建立呼出气一氧化氮正常值

目的探讨6-14岁儿童呼出气一氧化氮（FeNO）正常值范围及其影响因素。方法选取苏州市6-14岁在校儿童进行问卷调查及FeNO、肺功能、外周血嗜酸粒细胞（EOS）计数的检测,筛选出健康儿童建立FeNO正常值。FeNO的测定采用电化学法,根据美国胸科学会/欧洲呼吸学会指南进行操作。分析性别、年龄、身高、体重、外周血EOS计数、肺功能和FeNO的相关性。结果参与调查的450名儿童中符合纳入标准者225名（男生107名,女生118名）进入分析。FeNO值呈偏态分布,经自然对数转换后呈正态分布。FeNO平均值为11ppb（95%CI：5-28ppb）,最小值〈5ppb,最大值为83ppb。男生FeNO平均值为11ppb（95%CI：5-31ppb）,女生FeNO平均值为11ppb（95%CI：5-25ppb）。FeNO与外周血EOS计数相关性最为显著（r=0.291,P〈0.001）,与身高（r=0.148,P=0.027）和FEV1（r=0.138,P=0.038）显著相关;〉9岁儿童FeNO显著高于≤9岁儿童（P=0.002）;FeNO与性别、体重、BMI、FEV1/FVC无显著相关性。结论苏州地区6-14岁儿童FeNO正常参考值为5-28ppb;FeNO水平与外周血EOS计数、身高、FEV1显著相关。

Reference values and determinants of fractional exhaled nitric oxide in 225 healthy children in Suzhou

Objectives The aim of this study was to establish FeNO reference values for healthy school-aged children in Suzhou according to the international guidelines, and to assess the determinants of FeNO. Methods Children aged 6-14 years were recruited from two public schools in Suzhou. The subjects completed a respiratory questionnaire, and were examined with measurements of FeNO, spirometry and blood eosinophil. Healthy children were screened to establish reference values of FeNO. FeNO was measured with a chemiluminescence analyzer according to American Thoracic Society guidelines （single breath online, exhalation flow 50 mL·s-1）. The associations between different determinants （sex, age, height, weight, BMI, peripheral blood EOS count, FEV1/FVC, lung function） and FeNO were analyzed. Results Finally, a total of 450 children participated in the study, and 225 children fulfilled the inclusion criteria of healthy subjects （107 boys and 118 girls）. FeNO data were skewed, and met normal distribution after natural logarithm transformation. The geometric mean of FeNO in 225 children was 11 parts per billion （ppb） （95%CI： 5-28 ppb）, the minimum value was below 5 ppb, and the maximum value was 83 ppb. The mean value was 11 ppb （95% CI：5-31 ppb） for boys and 11 ppb （95%CI： 5-25 ppb） for girls. In stepwise multiple regression analysis, peripheral blood EOS count was found to be the best independent variable for the regression equation for FeNO （r=0.291, P0.000 1）. Height （r=0.148, P=0.027） and FEV1 （r=0.138, P=0.038） were significantly correlated with FeNO. FeNO in children aged 9 years was significant higher than that in children aged ≤ 9 years（P=0.002）. Sex, weight, BMI and FEV1/FVC were not associated with FeNO. Conclusions FeNO reference values of healthy children aged 6 to 14 years in Suzhou should be considered to fall between the following ranges： 5-28 ppb, which is slightly higher than European and American children. FeNO levels in healthy school-aged children appear to be affected by EOS count and height significantly, followed by FEV1, and not influenced by sex, age, weight, BMI and FEV1/FVC.