摘要目的 探索呼出气一氧化氮(FeNO)测定对儿童咳嗽变异性哮喘(CVA)的临床诊断价值.方法 纳入2012年3月至2013年4月因咳嗽＞4周就诊于苏州大学附属儿童医院呼吸科门诊的84例患儿,其中CVA患儿38例[CVA组14例、CVA+上呼吸道咳嗽综合征(UACS)组24例]、非CVA患儿46例[UACS组34例、感染后咳嗽(PIC)组12例],另外纳入25名健康儿童作为健康对照组.测定各组患儿FeNO水平、诱导痰嗜酸粒细胞比例、咳嗽症状积分,比较CVA和其他不同病因慢性咳嗽患儿FeNO水平差异,绘制ROC曲线评价FeNO对儿童CVA的诊断价值,拟定FeNO的诊断临界点.结果 CVA组与CVA+ UACS组的FeNO水平分别为(37.2±13.8)和(40.1±13.8)ppb,差异无统计学意义(t=2.839,P=0.124),但均高于健康对照组、UACS组及PIC组(均P＜0.05).UACS组和PIC组的FeNO水平分别为(18.3±7.6)和(19.2±4.4) ppb(t=2.580,P=2.996),与健康对照组差异无统计学意义(均P＞0.05).CVA患儿吸入糖皮质激素治疗4周后随访,FeNO较快下降,与初诊比较差异有统计学意义(t=8.306,P＜0.01).CVA患儿诱导痰嗜酸粒细胞比例和FeNO呈直线正相关(r =0.568,P＜0.01).FeNO和咳嗽症状积分有相关性(r=0.402,P＜0.05).应用FeNO从慢性咳嗽患儿中诊断CVA的ROC曲线下面积为0.94,最佳界值点为25.5 ppb,诊断CVA的敏感度为84.0％,特异度为94.3％.结论 CVA患儿的FeNO高于其他慢性咳嗽病因儿童,并反映气道嗜酸性炎症水平,可能是诊断儿童CVA的敏感特异指标.

abstractsObjective To determine the diagnostic value of fractional exhaled nitric oxide (FeNO) measurement in diagnosis of Cough Variant Asthma (CVA) in children.Methods Outpatients with a cough ＞4 weeks visiting The Children' s Hospital Affiliated to Suzhou University from March 2012 to April 2013 were enrolled.FeNO was measured by a nitric oxide analyzer in accordance with American Thoracic Society guidelines.The levels of FeNO in CVA and other causes of chronic cough were compared.The value of FeNO was assessed and the optimal operating point of FeNO testing for the diagnosis of CVA was determined by the means of the receiver operating characteristic (ROC) curves.Results A total of 84 children with chronic cough were recruited,among whom 38 were diagnosed as having CVA.The levels of FeNO were not statistically different between patients with CVA [(37.2 ± 13.8) ppb] and patients with CVA combined with upper airway cough syndrome [UACS,(40.1 ± 13.8) ppb,P =0.124],but were both significantly higher than those in patients with UACS or with postinfectious cough (PIC),and the normal control group(P ＜0.01 respectively).There were 46 non-CVA patients,including 34 cases with UACS and 12 PIG,and their FeNO levels were not statistically different [(18.3 ± 7.6) to (19.2 ± 4.4) ppb,t =2.580,P =2.996].The levels of FeNO declined rapidly in CVA patients after inhaled corticosteroids during the 4 week follow-up.The proportion of eosinophils in the sputum from CVA patients was higher than that from the non-CVA patients,consistent with the level of FeNO,which showed a positive linear correlation with sputum eosinophils.The area under ROC curve was 0.94.The optimal diagnostic cutoff point was 22.5 ppb which was capable of differentiating CVA and non-CVA with a sensitivity of 84％,and a specificity of 94.3％.Conclusions The level of FENO was higher in CVA compared to other causes of chronic cough.FeNO,a marker of airway eosinophilic inflammation,may be helpful in the diagnosis of CVA in children with high sensitivity and specificity.