Fractional Exhaled Nitric Oxide Values Research Articles

Fractional Exhaled Nitric Oxide (FeNO) in Biomass Smoke-Associated Chronic Obstructive Pulmonary Disease.

To measure FeNO levels in patients with COPD-BS and to compare these with those of patients with stable COPD-TS and in healthy controls. Transversal, observational, descriptive, comparative, and analytical study. A total of 57 patients, including 23 with COPD-BS, 17 with COPD-TS, and 17 healthy control subjects. The measurement of FeNO was carried out on all of these by means of the on-line chemiluminescence technique; the values were expressed in parts per billion (ppb) for their analysis. It was observed that the FeNO values were similar between COPD-BS and COPD-TS and were significantly different between the healthy and stable COPD (both groups). No correlation was found between pulmonary function and symptoms with FeNO in any of the groups. The level of FeNO in stable COPD is found to be increased in a similar manner in COPD-BS and COPD-TS, with a significant difference on comparing it with that of the healthy subjects.

Identifying the predictive value of fractional exhaled nitric oxide (FeNO) for uncontrolled asthma in 3-7-year-old Thai children.

Fractional exhaled nitric oxide (FeNO) is the method for monitoring airway inflammation. However, a singular FeNO value cutoff may not adequately represent the control status across different ages and demographics. This study aimed to evaluate the correlation between FeNO values and asthma control levels, identifying an optimal cutoff point for children aged 3 to 7 years. This cross-sectional study was conducted at Naresuan University Hospital from April 1, 2023 to July 31, 2023. Inclusion criteria were asthmatic patients aged 3 to 7 years who were capable of following commands. Exclusion criteria included children who had a coronavirus disease 2019 (COVID-19) infection, those experiencing difficulty breathing, or unable to perform the FeNO measurement. Eligible patients were classified according to their level of asthma control and underwent FeNO testing. Out of 108 participants who successfully completed FeNO measurements, a significant difference in FeNO values was observed across controlled, partially controlled, and uncontrolled asthma groups, with uncontrolled asthma presenting significantly higher values. The optimal FeNO cutoff point for predicting uncontrolled asthma was identified as ≥15 ppb with a sensitivity 46.7%, specificity 86.0%, positive predictive value (PPV) 35.0%, negative predictive value (NPV) 90.9%. This study established a significant correlation between FeNO levels and uncontrolled asthma, FeNO cutoff point ≥15 ppb as the optimal value in predicting uncontrolled asthma in Thai children aged 3-7 years. Factors such as uncontrolled allergic rhinitis, symptoms at onset, smoking exposure, treatment compliance, and inhaled corticosteroid (ICS) usage were associated with FeNO values. The application of FeNO measurement should be integrated with clinical assessments and consideration of these associated factors.

Bronchial asthma with normal forced expiratory volume in 1 second (FEV1) compared with low FEV1.

Cough variant asthma (CVA) is characterized by cough as a sole symptom and normal pulmonary function. However, it is unclear whether CVA really common among asthmatic patients with normal forced expiratory volume in 1 second (FEV1). The aim of this study was to evaluate the incidence of cough alone symptom among the subjects with normal FEV1 and to evaluate their differences from ordinary asthmatic subjects. We defined normal FEV1 as ≥90% predicted based on the article of Kotti GH. Of the patients with normal FEV1, we chose subjects without wheeze, and the duration of cough was not to ask, since the symptoms often occurred with acute exacerbation and timing of visiting a doctor depended on each patient's perception. Test for airway hyperresponsiveness was not performed in this study. Visual analogue scale (VAS) scores for cough and dyspnea, FEV1, and fractional exhaled nitric oxide (FeNO) responsiveness to inhaled corticosteroid (ICS)/long-acting beta2 agonist (LABA) treatment were compared in patients with normal FEV1 and with low FEV1 <90%. Correlations of changes in symptoms with changes of FEV1, FeNO, peripheral eosinophil count, and serum immunoglobulin E (IgE) at single time point were also examined in each group and in overall patients. The participants were 329 physician-diagnosed treatment-naive patients with asthma who were divided into 187 in normal FEV1 and 142 in low FEV1 groups. Cough without dyspnea was present in 16 patients (8.6%) in the normal FEV1 group, suggesting candidates for CVA in this analysis were quite few. Improvement in symptoms after treatment was similar between both groups. But VAS scores of dyspnea were still higher in the low FEV1 group. The degree of improvement in FEV1 after ICS/LABA treatment was less in the normal FEV1 group than in the low FEV1 group, but was still evident. Peripheral eosinophil count, serum IgE, and FeNO values before treatment were lower in the normal FEV1 group. In overall patients, improvements of symptoms after treatment were significantly correlated with FEV1 changes. Improvement of dyspnea was also significantly related to peripheral eosinophil count and change of FeNO, whereas improvement of cough was not related to these T helper 2 (Th2) response markers. Candidates for CVA among the patients with asthma with predicted FEV1 ≥90% were few. Participants with normal FEV1 respond well to ICS/LABA treatment for improvement of symptom. The change of FEV1 after treatment, and the pre-treatment blood eosinophil count, serum IgE, and FeNO were lower in normal FEV1 cases than in low FEV1 cases. These observations suggest asthmatic patients with normal FEV1, including candidates for CVA having just common mild asthma. In overall participants, symptoms of cough and dyspnea were similar, but were not identical in relation to the Th2 background.

Role of fractional exhaled nitric oxide in patients with sickle cell disease

IntroductionPatients with sickle cell disease exhibit different patterns in pulmonary function tests. In particular, there is little evidence on the fractional exhaled nitric oxide (FeNO) test, and its value ranges and its interpretation in these patients have been under debate in recent years. MethodsWe conduced a cross-sectional, observational and descriptive study between November 2021 and January 2023 including patients aged 6–18 years with sickle cell disease able to perform the FeNO test. We applied the GLI-2012 reference values and the ERS/ATS standards. We defined statistical significance as P < 0.05. ResultsThe sample included 43 patients with a median age of 12 years (IQR, 10−15). We did not find an association between significantly elevated FeNO (≥25 ppb) and the diagnosis of asthma (P = 0.37), an obstructive pattern in spirometry (P = 0.67), a positive bronchodilator test (P = 0.53), clinical bronchial hyperreactivity in the context of cold or flu-like symptoms (P = 0.48), cough with exercise (P = 0.42) or nocturnal cough (P = 1.0), but found an association with peripheral eosinophilia (P < 0.01). ConclusionsWe found no association between FeNO values and the classic features of asthma (clinical or spirometric) in patients with sickle cell disease. Therefore, airway inflammation mechanisms are probably different in these patients.

Evaluation of selected biomarkers in the diagnosis of asthma in children

Introduction and objective: Asthma is one of the most common chronic diseases in the paediatric population. The aim of this study was to evaluate selected biomarkers: fractional exhaled nitric oxide (FeNO), eosinophil count, periostin; and potential biomarkers: progranulin, matrix metalloproteinase-9 (MMP-9) and tumour necrosis factor alpha (TNFα) in the diagnosis of asthma in children. Materials and methods: The study group consisted of 25 children with atopic asthma in a stable period of the disease, aged 6–17 years. The control group consisted of 21 healthy children aged 6–18 years with no history of allergic diseases. Results: Significantly higher serum periostin levels were observed in children with asthma compared to the control group. There were no statistically significant differences in progranulin, periostin and MMP-9 levels between asthmatic children vs. healthy controls, or between patients with controlled vs. uncontrolled asthma. Children with uncontrolled asthma had significantly higher FeNO levels compared to children with controlled asthma. Exhaled FeNO levels were significantly higher in children with eosinophil levels above 0.3 × 103/µL than in those with eosinophil levels below 0.3 × 103/µL. Children with elevated FeNO had higher progranulin levels compared to children with normal FeNO values. There was a statistically significant positive correlation between FeNO and serum progranulin levels. Conclusions: Periostin may be used as a biomarker of atopic asthma in children. The applicability of FeNO and eosinophil count in the diagnosis of asthma in children has been confirmed. The role of progranulin and MMP-9 in the pathogenesis of asthma and their usefulness as a biomarker in children requires further study.

Role of FeNO in predicting the responsiveness of inhaled corticosteroids in COPD: a systematic review.

Fractional exhaled nitric oxide (FeNO) as a predictor of inhaled corticosteroid (ICS) response in asthma has been established. However, the same has not been established in chronic obstructive pulmonary disease (COPD). An optimal value of FeNO for prescribing and monitoring ICS response has not been quantified. To examine the evidence for this association. A systematic review was conducted of randomised controlled trials and observational studies examining the association between FeNO level and response to ICS in COPD patients. All studies examining this association were included. Five databases were searched thoroughly. Systematic screening, full-text reviews, and data extraction were carried out based on eligibility criteria. A total of 8690 studies were identified, 342 texts were screened fully, and six studies were included for the final review. One was a randomised controlled trial and the other five were non-randomised interventional trials. One study was conducted in asthma-COPD overlap (ACO patients). After ICS use, three studies found statistically significant correlations between FeNO and lung function improvement (FEV1), and three studies also found significant correlations between FeNO and COPD quality-of-life scores. Measurement of FeNO is non-invasive and standardised, with results available at the point of testing. Because of the small sample size and short duration of studies, exacerbation frequencies were not measured. Despite this, the review suggests that FeNO may be a potential biomarker for assessing ICS response in COPD. Further research that stratifies patients by FeNO levels and assesses the impact on acute exacerbations is needed to understand its potential value in routine clinical practice.

Fractional exhaled nitric oxide, a potential biomarker for evaluating glucocorticoids treatment and prognosis in allergic bronchopulmonary aspergillosis

BackgroundAllergic bronchopulmonary aspergillosis (ABPA) is characterized by enhanced TH2 inflammatory response. Fractional exhaled nitric oxide (FeNO) measurement has been used as a valuable tool in predicting the development and management of asthma, another typical TH2 inflammation. However, the clinical significance of FeNO in ABPA remains unclear. ObjectiveTo investigate the association between FeNO and the prognosis of patients with ABPA to provide a basis for the use of FeNO in evaluating the efficacy of glucocorticoids in ABPA treatment. MethodsThis study comprised 2 parts; 58 patients were enrolled in the retrospective study. Clinical indexes in patients with different prognoses were compared, and receiver operating characteristic curve analysis was used to determine the threshold value. The prospective observational study involved 61 patients who were regularly followed up at 4 to 6 weeks and 6 months since the initial treatment. Patients were grouped on the basis of baseline FeNO values; correlation analysis was performed in the clinical data. ResultsDifferent prognoses were observed between patients with high and low baseline FeNO values, with a threshold value of 57 parts per billion. The percentage of Aspergillus fumigatus-specific IgE, percentage of positive A fumigatus-specific IgG, and relapse/exacerbation rate differed significantly between the high and low FeNO groups. Patients with higher FeNO needed longer treatment duration and showed shorter interval between glucocorticoid withdrawal and the next relapse/exacerbation. ConclusionOur findings indicate that the level of FeNO is associated with the prognosis of ABPA. It can serve as an independent and valuable biomarker for evaluating the effectiveness of glucocorticoid treatment.

Lower Arginine Bioavailability, Increased FeNO Levels, and Airway Resistance on Impulse Oscillometry Are Characteristics of Asthma in Children and Young Adults with Sickle Cell Disease.

Background and Objectives: Data on characteristics of asthma in children with sickle cell disease (SCD) is conflicting. Recently, the L-arginine pathway has gained attention in the pathogenesis of asthma and SCD. This study aimed to determine the distinctive clinical and laboratory features and the role of arginine metabolism in asthmatic children with SCD. Materials and Methods: A total of 52 children and adolescents with SCD, including 24 with asthma (SCD-A) and 28 without asthma (SCD-NA), and 40 healthy controls were included. A questionnaire, atopy tests, fractional exhaled nitric oxide (FeNO), and lung function tests were employed. Serum metabolites of the arginine pathway were measured. The results of the three groups were compared. Results: The demographic characteristics and atopy markers of the three groups were similar. FEV1%, FEV1/FVC, MMEF%, and total lung capacity (TLC%) values of SCD-A patients were not significantly different from the SCD-NA group, but they were significantly lower than the values measured in the controls. FeNO values greater than 35 ppb were present only in the SCD-A group. In impulse oscillometry, median resistance values at 5 Hz (R5)% were higher in both SCD subgroups than in healthy controls (p = 0.001). The (R5-20/R5)% values were higher in the SCD-A group (p = 0.028). Serum arginine levels and arginine bioavailability indices were significantly lower in the SCD-A group than in the SCD-NA group and healthy controls (p = 0.003 and p < 0.001). Conclusions: Asthma in children with SCD was not associated with atopy or low FEV1/FVC levels. However, lower arginine bioavailability and higher FeNO levels differentiated asthma in patients with SCD. High R5% and (R5-20/R5)% values indicated increased airway resistance in SCD, with a predominance of small airway disease in asthmatics.

Lack of Association between Inhaled Corticosteroid Use Based on the Exhaled Nitric Oxide and Acute Exacerbation of Chronic Obstructive Pulmonary Disease.

Fractional exhaled nitric oxide (FeNO) is known to useful biomarker for detecting eosinophilic airway inflammation. However, there is a lack of evidence regarding the role of FeNO in chronic obstructive pulmonary disease (COPD). We aimed to assess whether elevated FeNO and its impact on treatment change into an inhaled corticosteroid (ICS)-containing regimen and association with acute exacerbation (AE) in patients with COPD. We retrospectively analyzed 107 COPD patients without a history of asthma from March 2016 to December 2019. The patients whose FeNO value was more than 50 parts per billion (ppb) were defined into the high FeNO group. Multivariable analysis with logistic regression was used to identify factors associated with AE in COPD. The median FeNO value was 32 ppb (interquartile range, 19 to 45) and 34 (20.0%) patients were classified as high FeNO group (median 74 ppb). In the high FeNO group, changes in inhaler treatment into an ICS-containing regimen occurred in 23 of 34 patients after the measurement of FeNO. In multivariate analysis, high FeNO was not a contributing factor for AE, but only the high blood eosinophil count (≥300 cells/μL) was associated with AE (adjusted odds ratio, 2.63; 95% confidence interval, 1.01 to 6.91; p=0.049). High FeNO value had a significant impact on the prescription of ICSs in COPD patients, but it did not show a significant association with AE either on its own or with changes in treatment.

The value of bronchodilator response in FEV1 and FeNO for differentiating between chronic respiratory diseases: an observational study

BackgroundThere is no uniform standard for a strongly positive bronchodilation test (BDT) result. In addition, the role of bronchodilator response in differentiating between asthma, chronic obstructive pulmonary disease (COPD), and asthma–COPD overlap (ACO) in patients with a positive BDT result is unclear. We explored a simplified standard of a strongly positive BDT result and whether bronchodilator response combined with fractional exhaled nitric oxide (FeNO) can differentiate between asthma, COPD, and ACO in patients with a positive BDT result.MethodsThree standards of a strongly positive BDT result, which were, respectively, defined as post-bronchodilator forced expiratory volume in 1-s responses (ΔFEV1) increasing by at least 400 mL + 15% (standard I), 400 mL (standard II), or 15% (standard III), were analyzed in asthma, COPD, and ACO patients with a positive BDT result. Receiver operating characteristic curves were used to determine the optimal values of ΔFEV1 and FeNO. Finally, the accuracy of prediction was verified by a validation study.ResultsThe rates of a strongly positive BDT result and the characteristics between standards I and II were consistent; however, those for standard III was different. ΔFEV1 ≥ 345 mL could predict ACO diagnosis in COPD patients with a positive BDT result (area under the curve [AUC]: 0.881; 95% confidence interval [CI] 0.83–0.94), with a sensitivity and specificity of 90.0% and 91.2%, respectively, in the validation study. When ΔFEV1 was < 315 mL combined with FeNO < 28.5 parts per billion, patients with a positive BDT result were more likely to have pure COPD (AUC: 0.774; 95% CI 0.72–0.83).ConclusionThe simplified standard II can replace standard I. ΔFEV1 and FeNO are helpful in differentiating between asthma, COPD, and ACO in patients with a positive BDT result.

Lung Involvement in Patients with Ulcerative Colitis: Relationship between Exhaled Nitric Oxide and Lung Function.

Ulcerative colitis (UC) is characterized by immune system dysregulation with frequent extraintestinal manifestations, including airway involvement. A reduction in CO diffusing capacity and functional alterations in small airways have been described. An extended analysis of fractional exhaled nitric oxide (FeNO) may distinguish the sites of production, and the presence of small airway inflammation may be a useful, non-invasive marker for patient follow-up. The aim of our study was to compare the PFTs as well as FeNO and CANO values of UC patients with different clinical disease activities and healthy subjects to reveal lung function abnormalities and the presence of subclinical airway inflammation. We enrolled 42 adult outpatients at different clinical activity stages of UC (39 ± 13 years) and a healthy control group of 41 subjects (29 ± 3 years). C-reactive protein (CRP) and FeNO values at different flows (50,100, and 200 mL/s) were collected. All patients performed pulmonary function tests (PFTs) with static volumes and diffusing capacity (DLCO). FeNO and CANO values were significantly increased in UC patients when compared with controls (p = 0.0008 and p < 0.0001, respectively) and were proportional to disease activity (FeNO class 3: 28.1 ppb vs. classes 1-2: 7.7 ppb; CANO values class 3: 8.6 ppb vs. classes 1-2: 2.7 ppb (p < 0.0001)). TLC and DLCO were significantly reduced in severe (Mayo 3) UC patients (p = 0.010 and p = 0.003, respectively). The results of this study show significant lung functional abnormalities in UC patients and suggest the presence of airway inflammation directly correlated with disease activity, suggesting the need for an integrated approach in routine assessment.

Predictive Value of Fractional Exhaled Nitric Oxide (FeNO) in the Diagnosis of Asthma for Epidemiological Purposes-An 8-Year Follow-Up Study.

The follow-up included 128 (out of 447) children, 70 girls and 58 boys. The FeNO was measured at baseline only. The prevalence of asthma-like symptoms was measured with the adopted version of the ISAAC questionnaire. After 8 years of FeNO measurement, 5 new cases of asthma, 2 cases of attacks of dyspnoea, 1 case of wheezy in the chest, and 18 cases of allergic rhinitis occurred. The FeNO values, measured at the baseline of the study, for new cases of the above diseases were 53.4 ± 75.9 ppb, 11 ± 1.5 ppb, 12.0 ppb, and 16.3 ± 12.4 ppb, respectively. The best diagnostic accuracy parameters were found in the new cases of asthma, where the sensitivity was 40.0%, the specificity was 98.6%, and the AUC was 66.6%. The diagnostic odds ratio was 46.9 when considering the FeNO cut-off >35 ppb. The FeNO measurement is a fair method for asthma prognosis in early school-aged children with asthma-like symptoms measured on the population level but requires further confirmation at the clinical level with more accurate diagnostic tools.

Effect of overweight/obesity on relationship between fractional exhaled nitric oxide and airway hyperresponsiveness in Chinese elderly patients with asthma.

Purpose: This retrospective study investigates the influence of overweight and obesity status on pulmonary function, airway inflammatory markers, and airway responsiveness in elderly asthma patients. Methods: Patients with asthma older than 65years old who completed a bronchial provocation test (BPT) or bronchial dilation test (BDT) and a fractional exhaled nitric oxide (FeNO) test between December 2015 and June 2020 were identified retrospectively for this study. All of the patients were categorized into overweight/obesity and non-obesity groups based on their BMI. Pulmonary function test (PFT) and FeNO measurements were accomplished according to the 2014 recommendations of the Chinese National Guidelines of Pulmonary Function Test and American Thoracic Society/European Respiratory Society recommendations, respectively. Results: A total of 136 patients with an average age of 71.2 ± 5.40years were identified. The average BMI was 23.8 ± 3.63, while the value of FeNO was 42.3 ± 38.4 parts per billion (ppb). In contrast to the non-obesity group, which had a value of 48.8 ± 43.1 ppb for FeNO, the overweight/obesity group had a significant lower value of 35.4 ± 31.4 ppb. There was no significant difference in the proportion of individuals with high airway hyperresponsiveness between the overweight/obesity and non-obesity groups (96 patients in total). Multiple linear regression analysis established an inverse correlation between FeNO and Provocation concentration causing a 20% fall in FEV1(PC20) but excluded significant relationships with age and BMI. The model's R is 0.289, and its p value is 0.045. Conclusion: The elderly Chinese Han asthmatics with overweight/obesity had lower FeNO levels than those with non-obese according to our findings. In addition, the FeNO level was inversely correlated between FeNO levels and PC20 in elderly asthmatics.

The Relationship of Fractional Exhaled Nitric Oxide in Patients with AECOPD.

To identify the relationship between patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD) and their fractional-exhaled nitric oxide (FeNO) levels. Patients diagnosed with AECOPD in the respiratory department of Beijing Chaoyang Hospital from June 2017 to August 2019 were recorded. The demographic data, FeNO value, peripheral blood eosinophil count, number of acute exacerbations in the past year, pulmonary function test, use of inhaled glucocorticoids (ICS) and other data were collected and analyzed. FeNO was measured again three months after discharge, the participants were assessed to determine if the stable period criteria were met. A total of 214 patients met the requirements of this study. 25ppb for FeNO was used as the cutoff for further analysis. The proportion of males, number of acute exacerbations in the past year, number of ICS users, leukocyte count and eosinophil count in the high FeNO-level group was significantly higher than that in the low-level group (P < 0.05). The results showed that the number of acute exacerbations in the past year, number of ICS users, and eosinophil count were statistically significant in the model (P < 0.05). The study also showed that the level of FeNO in the acute exacerbation phase was significantly higher than that in the stable phase. The ROC curve that the area under the curve used by FeNO to predict ICS used is 0.631 (95% CI: 0.526-0.736), and the corresponding P value is 0.022. FeNO is closely related to activated T2 inflammation and eosinophil count in COPD patients. The FeNO levels can be used as an index to evaluate the severity of COPD and predict the recovery of activity after ICS treatment. FeNO can predict the use of ICS and is a beneficial supplement to eosinophils.

Association between fractional exhaled nitric oxide and therapeutic adherence to controller management in pediatric asthma patients.

Guidelines for asthma management recommend, before establishing additional therapeutic behaviors, to confirm correct use and adequate therapeutic adherence to treatment. Evidence exists on the use of fractional exhaled nitric oxide (FeNO) values for monitoring therapeutic adherence in adults. It is important to establish whether there is a correlation between FeNO and therapeutic adherence in children. This study aims to provide new knowledge about the relationship between FeNO and therapeutic adherence in asthmatic children. Analytical cross-sectional study including asthma patients 5-18 years of age, attending follow-up at Hospital Militar Central (HMC) between May and November 2022 in Colombia. A sociodemographic survey was carried out, followed by the Pediatric Inhaler Adherence Questionnaire (PIAQ), and asthma control test (ACT) or childhood asthma control test (cACT). We defined adequate therapeutic adherence as not missing a single application of inhaled steroids in the last 15 days according to PIAQ. A poisson regression model was carried out including relevant predictors for therapeutic adherence such as FeNO values, age, tobacco exposure at home, atopy, and time since initiation of use of inhaled controller. Eighty-two children with a median age of 10 years (interquartile range: 7-12 years) were included. Adequate therapeutic adherence was reported by 68.3%. After adjusting for age, sex, exposure to cigarette smoke, duration of controller therapy, and atopy, FeNO < 20 ppb was independently associated with adequate therapeutic adherence (RR = 1.5, p = .04, 95% confidence interval: 1.03-2.19). FeNO values seem to be useful to identify pediatric patients with asthma who have adequate adherence to inhaled steroids in a MIC.

Validity of fractional exhaled nitric oxide and small airway lung function measured by IOS in the diagnosis of cough variant asthma in preschool children with chronic cough

BackgroundTo investigate the role of combined impulse oscillometry (IOS) and fractional exhaled nitric oxide (FeNO) in the diagnosis of cough variant asthma (CVA) in preschool children.MethodsA total of 197 preschool-aged children with chronic cough were selected from the paediatric outpatient clinic. Allergy histories were collected for all children along with IOS and FeNO. Paediatric respiratory specialists divided the children into a CVA group (n = 90) and a noncough variant asthma (nCVA) group (n = 107) according to the diagnostic criteria for CVA After diagnostic treatment, the correlation between the FeNO and IOS values and the diagnosis in the two groups was analysed, and the area under the curve (AUC) of each index was calculated.Results(1) X5 was significantly different between the CVA group and the nCVA group (− 4.22 vs. − 3.64, p < 0.001), as was the FeNO value (29.07 vs. 16.64, p < 0.001). (2) Receiver operating characteristic (ROC) analysis showed that the AUCs of FeNO alone and X5 alone were 0.779 and 0.657, respectively, while the AUC of FeNO (cut-off value of 18 ppb) plus X5 (cut-off value of -4.15 cmH2O/(l/s)) reached 0.809.ConclusionsChildren with CVA may have small airway dysfunction at an early stage. For preschool children with chronic cough, the combination of FeNO and X5 can better identify those with CVA.Trial registration number: This trial was registered with and approved by the Chinese Clinical Trial Registry, with registration number ChiCTRcRRC-17011738, and was reviewed and approved by the Ethics Committee of Southwest Hospital.

Use of fractional exhaled nitric oxide as a potential predictor of bronchodilator response.

Nitric oxide (NO) is an important product of eosinophilic metabolism, and its increase is associated with bronchial remodeling and airway hyperresponsiveness. Fractional exhaled NO (FENO) in the expired air of patients with suspected or diagnosed asthma has been used as a marker for eosinophilic inflammation. This cohort study included asthmatic patients classified under steps 3, 4, or 5 of the global strategy for asthma management and prevention. In the morning of the same day, all patients underwent blood collection for eosinophil counts, followed by FENO measurement and spirometry. We considered 2 groups based on the bronchodilation (BD) response on spirometry (>10% of FVC or FEV1): positive (BD+) and negative (BD-). Differences between the 2 groups were analyzed for demographic features, FENO values, and predictive correlations between FENO and BD. Both groups of patients showed an increase in the eosinophil count (BD+, P = .03; BD-, P = .04) and FENO values (P = .015 for both) with an increase in the asthma severity from step 3 to step 5 of the global strategy for asthma management and prevention. The correlations of FENO and eosinophils as well as FENO values and BD + were 0.127 (95% confidence interval,-0.269 to -0.486) and 0.696 (95% confidence interval, 0.246-0.899; P = .007), respectively. Measuring FENO levels may be useful for identifying patients with BD+.

The Practical Role of FEF25-75 in Young Patients with Allergic Rhinitis.

Allergic rhinitis (AR) is a relevant risk factor asthma as it may frequently precede asthma onset. There is evidence that lung function may be early impaired in AR patients. In this regard, the forced expiratory flow at 25%-75% of vital capacity (FEF25-75) could be a reliable marker of bronchial impairment in AR. Therefore, the present study investigated the practical role of FEF25-75 in young people with AR. The parameters included history, body mass index (BMI), lung function, bronchial hyperresponsiveness (BHR), and fractional exhaled nitric oxide (FeNO). This cross-sectional study included 759 patients (74 females and 685 males, mean age of 29.2 years) suffering from AR. The study demonstrated a significant association between low FEF25-75 values and BMI (OR 0.80), FEV1 (OR 1.29), FEV1/FVC (OR 1.71), and BHR (OR 0.11). Stratifying the patients on the basis of the presence (or absence) of BHR, sensitization to house dust mites (OR 1.81), AR duration (OR 1.08), FEF25-75 (OR 0.94), and FeNO (OR 1.08) were associated with BHR. Stratifying patients based on high FeNO values (>50 ppb), BHR was associated with high FeNO (OR 39). In conclusion, the present study showed that FEF25-75 was associated with low FEV1 and FEV1/FVC and BHR in AR patients. Therefore, spirometry should be considered in the long-term workup of patients with allergic rhinitis as impaired FEF25-75 might suggest an initial progression toward asthma.

Effectiveness of FeNO-guided treatment in adult asthma patients: A systematic review and meta-analysis.

Asthma control is generally monitored by assessing symptoms and lung function. However, optimal treatment is also dependent on the type and extent of airway inflammation. Fraction of exhaled Nitric Oxide (FeNO) is a noninvasive biomarker of type 2 airway inflammation, but its effectiveness in guiding asthma treatment remains disputed. We performed a systematic review and meta-analysis to obtain summary estimates of the effectiveness of FeNO-guided asthma treatment. We updated a Cochrane systematic review from 2016. Cochrane Risk of Bias tool was used to assess risk of bias. Inverse-variance random-effects meta-analysis was performed. Certainty of evidence was assessed using GRADE. Subgroup analyses were performed based on asthma severity, asthma control, allergy/atopy, pregnancy and obesity. The Cochrane Airways Group Trials Register was searched on 9 May 2023. We included randomized controlled trials (RCTs) comparing the effectiveness of a FeNO-guided treatment versus usual (symptom-guided) treatment in adult asthma patients. We included 12 RCTs (2,116 patients), all showing high or unclear risk of bias in at least one domain. Five RCTs reported support from a FeNO manufacturer. FeNO-guided treatment probably reduces the number of patients having ≥1 exacerbation (OR = 0.61; 95%CI 0.44 to 0.83; six RCTs; GRADE moderate certainty) and exacerbation rate (RR = 0.67; 95%CI 0.54 to 0.82; six RCTs; moderate certainty), and may slightly improve Asthma Control Questionnaire score (MD = -0.10; 95%CI -0.18 to -0.02, six RCTs; low certainty), however, this change is unlikely to be clinically important. An effect on severe exacerbations, quality of life, FEV1, treatment dosage and FeNO values could not be demonstrated. There were no indications that effectiveness is different in subgroups of patients, although evidence for subgroup analysis was limited. FeNO-guided asthma treatment probably results in fewer exacerbations but may not have clinically important effects on other asthma outcomes.

Biomarkers for predicting type 2-high and uncontrolled asthma in real-world practice

BackgroundBlood eosinophil count (BEC), immunoglobulin (Ig) E, and fractional exhaled nitric oxide (FeNO) are key clinical indicators for identifying type 2 (T2) asthma. ObjectiveTo provide optimal cutoff points of T2 markers for assessing T2-high or uncontrolled asthma in real-world practice. MethodsVarious clinical and laboratory parameters were analyzed according to the result of T2 markers (BEC, serum-free IgE, and FeNO) in adults with asthma who had maintained antiasthmatic medications. The cutoff levels for representing uncontrolled asthma were determined using receiver operating characteristic analysis. Blood levels of periostin and eosinophil-derived neurotoxin were measured by enzyme-linked immunosorbent assay. Activation markers of circulating eosinophils (Siglec8+) and neutrophils (CD66+) were analyzed by flow cytometry. ResultsOf 133 patients with asthma, 23 (17.3%) had 3 T2 markers (BEC ≥ 300 cells/μL, serum-free IgE ≥ 120 ng/mL, and FeNO ≥ 25 parts per billion) and significantly higher levels of sputum eosinophils, blood eosinophil-derived neurotoxin, and Siglec8+ eosinophils but lower 1-second forced expiratory volume percentage, in addition to a higher rate of uncontrolled status (P < .05 for all). Furthermore, patients with uncontrolled asthma had significantly higher levels of FeNO and BEC with lower 1-second forced expiratory volume percentage (P < .05 for all). The optimal cutoff values for predicting uncontrolled asthma were found to be 22 parts per billion of FeNO levels, 161.4 cells/L of BECs, and 85.9 ng/mL of serum-free IgE levels. ConclusionWe suggest the optimal cutoff values of BEC, IgE, and FeNO for classifying T2-high or uncontrolled asthma, which could be applied as candidate biomarkers for targeting patients with asthma who require T2 biologics.