Diagnostic Value Of FeNO And CaNO Combined Assay In Children With Cough Variant Asthma

Objectiveexhaled nitric oxide is a widely recognized marker of human airway eosinophil inflammation.It is also noninvasive and convenient.In this study,FeNO(Fractional Exhaled Nitric Oxide,atmospheric canal nitric oxide),CaNO(Concentration of nitie oxide of the alveolar or acinar region,Changes of small airway nitric oxide)in children with different chronic cough etiology,as well as the pulmonary ventilation function,chronic cough symptoms and peripheral blood eosinophil(EOS)are investigated and discussed to find the correlation of them.To discuss the diagnostic and antidiastole value of FeNO and CaNO combined diagnose children with cough variant asthma.MethodsIn this study,ninety-one children diagnosed with chronic cough for the first time in the Chronic cough Clinic of Shenyang Children’s Hospital from November 2021 to November 2022 were selected as the experimental group,and thirty-one healthy children during the same period were selected as the normal control group.By fully understanding the medical history,physical examination,blood routine,total IgE,chest X-ray,cough symptom score,(VAS)Visual Analogue Scale,lung function and other examinations,the etiology and symptoms of the children with chronic cough were determined and evaluated,and the children were divided into four groups.They were(CVA)cough variant asthma group,(UACS)upper airway cough syndrome group,CVA with UACS group,(PIC)post-infectious cough group.Then,FeNO and CaNO combined determination,etiological treatment and dynamic observation were performed on the children.Four weeks later,the children were retumed to the hospital,and FeNO and CaNO combined determination,blood routine,total IgE,chest X-ray,cough symptom score,VAS,lung function and other examinations were performed on both the children and healthy control group to evaluate the status of the children.FeNO and CaNO measurements,pulmonary function indexes,peripheral blood EOS,cough symptom scores,VAS and other test data were collected for each group,and the data were collated and analyzed statistically by SPSS26.0 software.Results1.Comparison of FeNO results in different etiological groups:there was no significant difference between CVA group and CVAcombined with UACS group,but they were significantly higher than UACS,PIC and control group(P<0.001,0.001,P<0.001;P<0.001,P<0.001,P<0.001);UACS group was significantly higher than control group(P=0.001).There was no significant difference between PIC and UACS group and control group.2.Comparison of CaNO results among different etiological groups:there was no significant difference between CVA group and CVA combined with UACS group,but they were significantly higher than UACS,PIC and control group(P<0.001,P<0.001,P<0.001;0.022,0.022,0.007);UACS group was significantly higher than control group(P<0.001).There was no significant difference between PIC group,UACS group and control group.3.FeNO level in children with chronic cough before treatment was significantly correlated with FEV1,FEV1/FVC,MEF25%,MEF50%,MEF25-75%,peripheral blood ensinophilia,cough symptom score,visual analog score,etc(P=0.001,P<0.001,P<0.001,P=0.008,P=0.016,P<0.001,P<0.001,P<0.001),no correlation with FVC.Before treatment,CaNO was significantly correlated with FEV1,FEV1/FVC,MEF25%,peripheral blood eosinophilia,cough symptom score and visual analog score in children with chronic cough(P=0.009,P<0.001,P=0.006,P<0.001,P<0.001,P=0.002).It is not correlated with FVC,MEF50%,MEF25-75%,etc4.(1)The best threshold for FeNO diagnosis of CVA was 20.5ppb,the sensitivity was 98.1%,the specificity was 90.3%and the area under ROC curve was 0.986.(2)The best threshold value of CaNO for diagnosing CVA was 3.85ppb,sensitivity was 90.6%,specificity was 93.5%,and area under ROC curve was 0.983.(3)The area under ROC curve of FeNO combined with CaNO in diagnosing CVA was 0.990,the sensitivity was 98.1%,and the specificity was 93.5%.(4)The best threshold of FEV1/FVC%for diagnosing CVA was 94.5,the sensitivity was 86.8%,the specificity was 96.8%,and the area under ROC curve was 0.951.(5)The best threshold value,sensitivity,specificity,and area under ROC curve were 81.5,73.6%,96.8%,and 0.921 for 25%of MEF in the diagnosis of CVA.(6)The best cut-off value,sensitivity,specificity,and area under the curve were 83.5,71.7%,96.8%,and 0.883 for MEF50%diagnosis of CVA.(7)The best cut-off value of MEF25-75%for the diagnosis of CVA was 86,the sensitivity was 92.5%,the specificity was 80.6%,and the area under ROC curve was 0.934.Conclusions1.FeNO and CaNO levels were different in chronic cough with different etiologies;FeNO and CaNO levels were most significantly increased in children with cough variant asthma characterized by eosinophilic airway inflammation.2.When FeNO is higher than 20.5ppb and CaNO is higher than 3.85ppb,they will have higher sensitivity and specificity in the diagnosis of CVA,which can be used as a reference index in the diagnosis and differential diagnosis of CVA,and is better than FEV1/FVC%,MEF25%,MEF50%,MEF25-75%and lung function indicators.However,FeNO and CaNO combined assay is superior to FeNO or CaNO alone,so FeNO and CaNO combined assay is helpful for etiological diagnosis and differential diagnosis of children with CVA.3.Compared with FeNO,CaNO and FeNO have a better correlation with eosinophilic inflammation and cough syumptoms in children with chronic cough.The combined determination of CaNO and FENo can improve the diagnosis and differential diagnosis efficiency of CVA and other causes mainly characterized by eosinophilic inflammation.