Clinical Significance Of Exhaled Nitric Oxide Combined With Pulmonary Function In Assessing Airway Injury In Children With Asthma

Objective To investigate the significance of different flow velocity exhaled nitric oxide（e NO）combined with pulmonary ventilation function test for the evaluation of airway injury in children with asthma,and to analyze the diagnostic efficacy.Methods The general data were collected from 180 outpatients and inpatients aged 4-16 years attending the Maternal and Child Health Hospital of Inner Mongolia Autonomous Region from July 2020 to October 2022,and were divided into 60 cases each in the acute asthma attack group,asthma remission group and respiratory tract infection group according to the inclusion criteria,sixty normal children enrolled in the e NO normal values in children aged 6-18 years project conducted in our hospital in 2018 in our region were also selected as the control group.The results of Fe NO₅₀,Ca NO and pulmonary ventilation function indicators were collected from all children,and the differences in Fe NO₅₀,Ca NO,FEV₁%pred（actual value as a percentage of predicted value）,FEV₁/FVC%pred,PEF%pred,FEF₂₅%pred,FEF₅₀%pred,FEF₇₅%pred and MMEF%pred were compared between the groups.ROC curves were plotted to analyse the diagnostic efficacy of e NO and pulmonary ventilation function test alone and in combination for asthma in children.Results 1)General data:60 cases in each group in the acute asthma attack group,asthma remission group,respiratory tract infection group and normal group.There was no statistical difference in age,gender,height and weight between the groups（P>0.05）.2)Comparison of e NO indicators:（1）Fe NO₅₀:Fe NO₅₀levels were significantly different between groups（F=85.104,P<0.001）,with the highest in the acute asthma attack group（41.52±17.55）,lower in the asthma remission group（30.00±9.79）than the acute asthma attack group,lower in the respiratory tract infection group（24.47±6.14）than the asthma remission group and the normal group was the lowest of the four groups（10.85±3.97）,with statistically significant differences between each of the two groups（P<0.05）.（1）Ca NO:No significant difference was seen in Ca NO levels between the acute asthma attack group,the remission group and the respiratory tract infection group,but the mean values of all three groups were significantly different compared to the normal group（F=26.973,P<0.001）.3)Comparison of pulmonary ventilation function indicators:FEV₁%pred,FEV₁/FVC%pred,FEF₂₅%pred,FEF₅₀%pred,FEF₇₅%pred and MMEF%pred were all significantly lower in the acute asthma attack group than in the asthma remission group,with statistically significant differences（P<0.05）.4)Analysis of the diagnostic efficacy of e NO and pulmonary ventilation function alone and in combination:Fe NO50 had a cut-off value of 24.5ppb for the diagnosis of asthma,a sensitivity of 76.67%,a specificity of 80.00%,an AUC of 0.88（95%CI 0.84 to 0.92）for Fe NO50 alone,the AUC for FEV1%pred alone was 0.65（95%CI 0.58,0.72）,the AUC for the combined Fe NO50 and FEV1%pred 0.88（95%CI 0.84,0.92）was the same as the AUC for Fe NO50alone but significantly higher than the AUC for FEV1%pred alone.The cut-off value for Ca NO for the diagnosis of asthma was 7.65 ppb,with a sensitivity of 74.17%and a specificity of 55.83%.The AUC for Ca NO alone was 0.66（95%CI 0.59-0.73）,the AUC for MMEF%pred alone was 0.70（95%CI 0.63-0.76）,and the AUC for the combination of the two tests was 0.73（95%CI 0.67-0.80）higher than the AUC for both tests alone.Conclusion 1)Fe NO50 is higher in the acute asthma attack group than in the remission group,and higher in the remission group than in the respiratory infection and normal groups.Therefore,Fe NO50 can assist in the diagnosis of childhood asthma,predict acute attacks,monitor the level of treatment in remission,and effectively assess airway damage in children during all phases of asthma.Fe NO50 was higher in the respiratory tract infection group than in the normal group,and Fe NO50 can also reflect airway inflammation in respiratory tract infectious diseases.2)Ca NO levels were significantly higher in the acute asthma attack and remission groups than in the normal group,suggesting that Ca NO may provide some clues to the diagnosis of children with asthma,but no significant difference in Ca NO levels was seen when comparing the two groups,and acute asthma attacks in children cannot yet be predicted based on the magnitude of Ca NO values.3)The area under the ROC curve for the combined test of e NO and pulmonary ventilation increased compared to the two tests alone,and the combined test significantly improved the diagnostic efficacy of asthma in children.