Gender and age affect the levels of exhaled nitric oxide in healthy children

Can the Chinese study on the normal range of FeNO in children evaluate standardized asthma treatment efficacy in 6- to 12-year-old children?

Objective

By examining fractional exhaled nitric oxide (FeNO) levels and performing pulmonary function testing, this study explored whether the multicenter study on the normal range of FeNO in children in China can be used to evaluate standardized treatment efficacy in 6- to 12-year-old children with asthma.

Methods

A total of 115 children aged 6-12 years old who were first diagnosed with asthma and received standardized asthma treatment from April 2018 to July 2022 were selected. According to the FeNO level at the first visit, the subjects were divided into different high- and low-FeNO groups according to the American Thoracic Society (ATS) guidelines and the Chinese multicenter study recommendations. The consistency of the two grouping methods and the differences between the high- and low-FeNO groups were compared after standardized treatment. The grouping method that was the most suitable for children in the cross group was discussed.

Results

(i) There was fair consistency between the Chinese multicenter study recommendations and the ATS guidelines regarding the classification of high- and low-FeNO groups (Kappa = 0.338). (ii) Repeated-measures ANOVA showed that the level of improvement in FVC%, FEV1%, FEF25%, FEF50%, and FeNO in the American high- and low-FeNO groups differed with the duration of therapy (P < 0.05), however, there was no significant difference between the Chinese groups. (iii) FEV1% and FeNO improved more after treatment in the fixed high-FeNO group than in the cross group (P < 0.05).

Conclusion

The Chinese multicenter study on the normal range of FeNO in children in China has a limited role in evaluating standardized asthma treatment efficacy in 6- to 12-year-old children. The ATS guidelines are currently recommended for clinical assessment of asthma treatment efficacy.

The Effect of Obesity on Fractional Exhaled Nitric Oxide in School-Aged Children

Background: Fractional exhaled nitric oxide (FeNO) is recognized as a biomarker of eosinophilic inflammation. Current literature shows evidence that FeNO is influenced by many factors. Obesity is a chronic inflammatory state. In this study, we considered obesity as a potential factor that influences FeNO levels. The aim of the study was to analyze the association between body mass index (BMI, body mass (kg)/height (m)2) and FeNO levels in a young group of children. Methods: The participants in the study were 506 school-aged children who were randomly selected from primary schools located in Silesian Voivodship (Poland). The modified version of the Study of Asthma and Allergies in Childhood (ISAAC) questionnaire was used to assess the respiratory system status of children. FeNO was measured in 447 children according to European Respiratory Society and America Thoracic Society (ERS/ATS) recommendations. Body mass and height were measured by a medical body composition analyzer. BMI was defined and interpreted with Palczewska’s percentile charts. Results: In the study group there were 49.9% (n = 223) boys and 50.1% (n = 224) girls. The frequency of normal BMI was 76.8% (n = 172), overweight 13.7% (n = 31) and obesity 9.4% (n = 21) in girls, while the normal BMI was found in 71.3% (n = 159), overweight 11.6% (n = 26) and obesity 17% (n = 38) in boys, the differences not statistically significant (p = 0.05). The mean FeNO value in children with obesity was 16.1 ± 12.5 ppb, in children with normal BMI 15.8 ± 15.5 ppb and the lowest FeNO values were in children with overweight 15.3 ± 13.0 ppb; p = 0.9. The FeNO values after adjusting for age, sex, BMI and symptoms from respiratory system were depended on age and respiratory symptoms only. Conclusions: In 6–9 year old school children, FeNO levels are associated with age and health in relation to the respiratory system. The BMI should not be included when considering reference values for FeNO.

Fractional Exhaled Nitric Oxide in Teenagers and Adults with Atopic Dermatitis

Fractional exhaled nitric oxide (FeNO) is a non-invasive biomarker of eosinophilic airway inflammation and therapeutic response to corticosteroid treatment of respiratory diseases. Atopic dermatitis (AD), one of the most common allergic conditions of the skin, is a factor influencing the increase of FeNO. The main aim of this study was to determine differences between levels of FeNO in patients with AD and healthy controls as measured by an electrochemical analyzer. In total, 54 teenagers and adults with AD were recruited and compared with 34 healthy volunteers. The measurements of FeNO were taken using the Hyp’Air FeNO in participants. FeNO was statistically significantly higher in patients with AD than in healthy controls (60.5 ± 35.1 vs. 14.8 ± 5.1 ppb, p < 0.001). We found a strong positive significant correlation between FeNO and the number of positive skin prick tests among AD patients (R = 0.754, p < 0.001). There was no correlation between FeNO and duration of disease as well as SCORAD index among patients. Moreover, we also found no FeNO difference between the mild and moderate forms of AD. The presence of AD and the increasing number of positive skin prick tests increase FeNO, so the results of this measurement should be interpreted with caution in patients with respiratory diseases suffering from AD.

Factors Influencing the Concentration of Exhaled Nitric Oxide (FeNO) in School Children Aged 8–9-Years-Old in Krakow, with High FeNO Values ≥ 20 ppb

Background and Objectives: Measurement of fractional exhaled nitric oxide (FeNO) concentration is currently used as a non-invasive biomarker to assess airway inflammation. Many factors can influence the FeNO level. However, there have been no reports concerning factors attributed to FeNO levels in different age groups of children, especially those with high FeNO values. Therefore, this study aimed to assess the influence of selected factors on nitric oxide concentration in exhaled air in children aged 8–9 attending class 3 of public primary schools in Krakow with high FeNO values ≥ 20 ppb. Materials and Methods: The population-based study covered all third-grade pupils attending primary schools in the city of Krakow. Five thousand, four hundred and sixty children participated in the first screening stage, conducted from October 2017 to January 2018. Then, 792 participants with an FeNO level ≥ 20 ppb were selected. Finally, those selected pupils were invited to participate in the second stage, diagnostic, in April 2018. Four hundred and fifty-four children completed the diagnostic stage of the study, and their data was included in the presented analysis. Results and Conclusions: Significantly higher FeNO levels were observed in children diagnosed with the following diseases: asthma, allergic rhinitis, atopic dermatitis, and allergy (p < 0.05). In addition, it was observed that a higher FeNO concentration characterised children taking antihistamines compared to children not taking those medications (p = 0.008). In multivariate models, we observed that regardless of sex, age, BMI value, home smoking, and whether they were taking medications, children who had allergic rhinitis, or atopic dermatitis, or allergies had significantly higher FeNO levels. The strongest relationship was noted with allergic diseases. The results of our study may be of importance to clinicians when interpreting FeNO results, for example, when making a therapeutic decision.

The FeNO Normal Value Analysis of Healthy Children Aged 6-15 Years Old in Chengdu

OBJECTIVE

To investigate the fractional exhaled nitric oxide (FeNO) normal value of healthy children, and provide a reliable theoretical basis for clinical diagnosis.

METHODS

481 healthy children aged 6-15-y-old in three primary schools in Chengdu were subjected for FeNO detection. Through the statistical analysis, the upper limit normal value of FeNO among the healthy children was obtained, and the related influencing factors of FeNO value were analyzed.

RESULTS

Among the 481 heathy children, the geometric mean value of FeNO was 14.59 ppb (minimum value was 5 ppb, maximum value was 69 ppb), and the upper limit of normal value was 28 ppb. The age, height, and weight all have significant correlations with FeNO.

CONCLUSION

The upper limit of FeNO in healthy children aged 6-15-y-old was 28.0 ppb. Inflammation in the airway was suggested when the value of FeNO exceeds 28.0 ppb. Furthermore, the influencing factors such as age, weight, height must be considered.

"Poor Effort" Does Not Account for Reduced Forced Vital Capacity in Asthmatic Children

Purpose: Poor forced vital capacity (FVC) effort has been considered to be the main reason for FVC reduction by the ATS/ERS guideline; however, this has rarely been mentioned in previous studies. The present study aims to determine whether reduced FVC in asthmatic children is correlated to poor FVC effort. Methods: A total of 209 asthmatic children within 5-13 years old were included and divided into reduced FVC ("restricted," n = 66) and typical obstruction group ("obstructed," n = 143). Forced expiratory flows before and after bronchodilation were recorded in asthmatic children. The differences in clinical characteristics, spirometric results, FVC effort, and bronchodilator response were compared between two groups. Exhalation time (ET) was divided into effective ET (ETe) and plateau ET (ETp) by the start point of exhalation plateau on the time-volume curve. FVC effort was assessed by ET, ETp, and back extrapolated volume (EV)/FVC (%). Results: Asthmatic children in the restricted group had significantly higher slow vital capacity (SVC)/FVC (%), higher EV/FVC (%), shorter ET, shorter ETe, and longer ETp, when compared with those with obstructed. In the obstructed group, ET (r = 0.201, P = 0.016) and ETe (r = 0.496, P < 0.001) positively correlated with FVC, and ETp (r = -0.224, P = 0.007) negatively correlated with FVC. In the restricted group, FVC positively correlated with ETe (r = 0.350, P = 0.004) but not ET and ETp. FVC z-score significantly correlated with total IgE (n = 51, r = -0.349, P = 0.012) and with FEF_25-75% z-score (n = 66, r = 0.531, P < 0.001) in the restricted group. The further logistic regression revealed that the risk of restricted increased by 1.12 (95% CI, 1.04-1.22, P = 0.005) with every 1% increase in %ΔFVC. In subjects with restricted and bronchodilation tests, %ΔFVC was significantly associated with FeNO (n = 29, r = 0.386, P = 0.039), FEF_25-75% z-score (n = 29, r = -0.472, P = 0.010), and SVC/FVC (%) (n = 19, r = 0.477, P = 0.039) but not with EV/FVC (%), ET, ETe, or ETp (P > 0.05). Conclusion: These findings suggested that "poor FVC effort" does not account for the FVC reduction in asthmatic children. Short ET and high SVC/FVC (%) are characteristics of reduced FVC.

Influence of advanced glycation end products on rotator cuff

BACKGROUND

Most rotator cuff tears are the result of age-related degenerative changes, but the mechanisms underlying these changes have not been reported. Recently, advanced glycation end products (AGEs) have been regarded as an important factor in senescence. Therefore, we hypothesized that AGEs would have detrimental effects on rotator cuff-derived cells. In this study, we investigated the influence of AGEs on rotator cuff-derived cells in vitro and ex vivo.

METHODS

Rotator cuff-derived cells were obtained from human supraspinatus tendons. The cells were cultured in the following media: (1) regular medium with 500 μg/mL AGEs (High-AGEs), (2) regular medium with 100 μg/mL AGEs (Low-AGEs), and (3) regular medium alone (Control). Cell viability, secretion of vascular endothelial growth factor, and the expressions of hypoxia-inducible factor-1α, reactive oxygen species, and apoptosis were assessed after cultivation. An ex vivo tissue culture with AGEs was also performed to measure the tensile strength.

RESULTS

Cell viability in the High-AGEs group was significantly suppressed relative to that in the Controls. The amount of vascular endothelial growth factor secretion was significantly greater in the High- and Low-AGEs groups than in the Controls. Immunofluorescence stain demonstrated enhancement of hypoxia-inducible factor-1α and reactive oxygen species expressions and cell apoptosis in the High- and Low-AGEs groups relative to that in the Controls. In ex vivo mechanical testing, tensile strength was significantly higher in the Control group than in the AGEs groups.

DISCUSSION

These results indicated that AGEs caused age-related degenerative rotator cuff changes. The reduction of AGEs might prevent rotator cuff senescence-related degeneration.

Exhaled nitric oxide in pediatric patients with respiratory disease

Measurement of nitric oxide (NO) levels in exhaled air from the upper and lower airways is currently used as a non-invasive marker of inflammation in respiratory diseases. Assessment of NO exhaled from the lower air respiratory tract is considered to be a quick method for confirmation and control of asthma in patients as well as an estimation of treatment efficiency. The main aim of this study was to determine differences between levels of exhaled nitric oxide (fractional exhaled NO; FeNO) in patients with respiratory disease as measured by an electrochemical analyzer. Measurements were taken in 352 pediatric patients aged 4-17 with cystic fibrosis (CF) (n = 43), asthma (n = 69), allergic rhinitis (AR) (n = 70), asthma and AR (n = 128) and non-diseased children (n = 42) recruited from the Allergology Outpatient Department, Provincial Hospital No 2, Rzeszów. The second objective of this study was to assess any correlations between FeNO and clinical parameters of patients. The level of FeNO in patients with CF was normal when compared with control subjects (10.8 ± 2.9 versus 11.4 ± 6 ppb). We found significantly higher FeNO in patients with asthma (26.6 ± 15.3 ppb, p < 0.001), AR (18.4 ± 9.6 ppb, p < 0.01) as well as in patients with both asthma and AR (43.3 ± 31.1 ppb, p < 0.001) when compared to healthy children. Statistical analysis revealed a positive correlation between FeNO and age, height and weight of control subjects, and height in children with AR. FeNO was independent of sex, BMI, spirometry and blood results as well as the type of residence in control children and subjects with CF, asthma, AR and combined asthma and AR. In conclusion, we found normal levels of FeNO in children with CF and elevated levels in patients with asthma, AR and combined asthma and AR as compared to control subjects. Due to conflicting data, there is still a need for additional research, especially related to regarding factors that affect FeNO levels in respiratory disease.

FeNO level and allergy status among school children in Terengganu, Malaysia

Background: Almost one third of the world population suffers from allergic conditions. Respiratory symptoms are common in Malaysian children but there are few studies on fractional exhaled nitric oxide (FeNO), inclusive of field clinical test for asthma among children in Malaysia. The aim was to provide insight on factors related to level of FeNO among students in Terengganu, Malaysia.Methods: In total, 487 randomly selected students from eight secondary schools participated (13-14 years old). A Standardized questionnaire was used to obtained information on doctors' diagnosed asthma, current asthma and respiratory symptoms. FeNO measurement and skin prick test (SPT to common allergen) were conducted.Results: The geometric mean FeNO was 16.7 ppb. Totally, 38.4% of students had elevated FeNO level (>20 ppb) and 40.3% had had positive SPT to house dust mites allergens (HDM), Dermatophagoides pteronyssinus (Der p 1), Dermatophagoides farinae (Der f 1) or Felis domisticus (cat). Male gender, height, parental history of allergy, self-reported allergy, and atopy were associated with FeNO. In particular, a combination of sensitization to HDM or cat and elevated FeNO were associated with doctor-diagnosed asthma and self-reported allergy to food, pollen and cat.Conclusion: Asthma, respiratory symptoms and sensitization to HDM and cat are common among students and presence of elevated FeNO levels indicate ongoing airway inflammation.

Fractional exhaled nitric oxide as a predictor of response to inhaled corticosteroids in patients with non-specific respiratory symptoms and insignificant bronchodilator reversibility: a randomised controlled trial

BACKGROUND

Chronic non-specific respiratory symptoms are difficult to manage. This trial aimed to evaluate the association between baseline fractional exhaled nitric oxide (FeNO) and the response to inhaled corticosteroids in patients with non-specific respiratory symptoms.

METHODS

In this double-blind randomised placebo-controlled trial, we enrolled undiagnosed patients, aged 18-80 years, with cough, wheeze, or dyspnoea and less than 20% bronchodilator reversibility across 26 primary care centres and hospitals in the UK and Singapore. Patients were assessed for 2 weeks before being randomly assigned (1:1) to 4 weeks of treatment with extrafine inhaled corticosteroids (QVAR 80 μg, two puffs twice per day, equivalent to 800 μg per day beclomethasone dipropionate) or placebo. Randomisation was stratified by baseline FeNO measurement: normal (≤25 parts per billion [ppb]), intermediate (>25 tp <40 ppb), and high (≥40 ppb). The primary endpoint was change in Asthma Control Questionnaire (ACQ7) mean score. We used generalised linear modelling to assess FeNO as a predictor of response, estimating an interaction effect between FeNO and treatment on change in ACQ7. We did our primary and secondary analyses in the per-protocol set, which excluded patients with non-completion of the primary endpoint, non-compliance to treatment (ascertained by patient report), and study visits made outside the predefined visit windows. This study is registered on ClinicalTrials.gov, number NCT02294279.

FINDINGS

Between Feb 4, 2015, and July 12, 2016, we randomly assigned 294 patients to extrafine inhaled corticosteroid treatment (n=148) or placebo (n=146). Following exclusions due to protocol violations, we analysed 214 patients (114 extrafine inhaled corticosteroids and 100 placebo). We observed a significant interaction between baseline FeNO and treatment group for every 10 ppb increase in baseline FeNO, with the change in ACQ7 greater in the extrafine inhaled corticosteroids group than in the placebo group (difference between groups 0·071, 95% CI 0·002 to 0·139; p=0·044). The most common adverse events were nasopharyngitis (18 [12%] patients in the treatment group vs 13 [9%] in the placebo group), infections and infestations (25 [17%] vs 21 [14%]), and respiratory, thoracic, and mediastinal disorders (13 [9%] vs 17 [12%]).

INTERPRETATION

FeNO measurement is an easy and non-invasive tool to use in clinical practice in patients with non-specific respiratory symptoms to predict response to inhaled corticosteroids. Further research is needed to examine its role in patients with evidence of other airway diseases, such as chronic obstructive pulmonary disease.

FUNDING

Sponsored by OPRI with partial funding by Circassia and study drugs provided by TEVA.

Accuracy of maximal expiratory flow-volume curve curvilinearity and fractional exhaled nitric oxide for detection of children with atopic asthma

Purpose

Airway pathology in children with atopic asthma can be reflected by the concave shape of the maximal expiratory flow-volume (MEFV) curve and high fractional exhaled nitric oxide (FeNO) values. We evaluated the capacity of the curvilinearity of the MEFV curve, FeNO, and their combination to distinguish subjects with atopic asthma from healthy individuals.

Methods

FeNO and angle β, which characterizes the general configuration of the MEFV curve, were determined in 119 steroid-naïve individuals with atopic asthma aged 8 to 16 years, and in 92 age-matched healthy controls. Receiver operating characteristic (ROC) curve analyses were performed to determine the cutoff points of FeNO and angle β that provided the best combination of sensitivity and specificity for asthma detection.

Results

Asthmatic patients had a significantly smaller angle β and higher FeNO compared with healthy controls (both, P<0.001). For asthma detection, the best cutoff values of angle β and FeNO were observed at 189.3° and 22 parts per billion, respectively. The area under the ROC curve for the combination of angle β and FeNO improved to 0.91 (95% confidence interval [CI], 0.87–0.95) from 0.80 (95% CI, 0.75–0.86; P<0.001) for angle β alone and 0.86 (95% CI, 0.82–0.91; P=0.002) for FeNO alone. In addition, the combination enhanced sensitivity with no significant decrease in specificity.

Conclusion

These data suggest that the combined use of the curvilinearity of the MEFV curve and FeNO is a useful tool to differentiate between children with and without atopic asthma.

Association between fractional exhaled nitric oxide (FeNO) cutoff values (25 ppb) and risk factors of cough

INTRODUCTION

Cough is among the most common symptoms for patients to seek medical attention.

OBJECTIVES

The purpose of this study is to evaluate the association between fractional exhaled nitric oxide (FeNO) cutoff values (25 ppb) and risk factors related to cough, hoping to evaluate the feasibility of the FeNO cut point values (25 ppb) for clinical prediction of cough in etiology.

METHODS

In 107 adult patients with acute, subacute, or chronic cough, the FeNO, forced expiratory volume for 1 second (FEV1), forced vital capacity (FVC), blood routine (white blood cell and neutrophil), immunoglobulin E (IgE), lymphocyte eosinophils, and hemoglobin were measured. The Student's t-test was used to test the differences of FeNO levels compared with FEV1/FVC, lymphocyte, and hemoglobin level. For evaluating the correlation of FeNO levels with IgE, eosinophil, blood routine, pulmonary infection, and smoking status, the chi-square test was performed.

RESULTS

FeNO cutoff value (25 ppb) significantly correlated with serum IgE (P < .0001) between ≥200 IU/mL and <200 IU/mL level, eosinophil (P = .039) between ≥5% and <5% level, lymphocyte percentage (P = .032) and the ratio of FEV1/FVC (P = .032), while weakly correlated with pulmonary infection, blood routine (white blood cell and neutrophil), hemoglobin, and smoking.

CONCLUSION

The cutoff values of FeNO (≥25 ppb or <25 ppb) are useful for etiological detection of cough with high sensitivity.

Normal values of nasal NO and exhaled NO in young Chinese people aged 9 - 22 years

Objective

To assess the normal levels of nasal nitric oxide (NNO) and fractional exhaled nitric oxide (FENO) in healthy Chinese young people, and to determine whether the obtained values were associated with age, sex, height, weight, BMI (body mass index) or BSA (body surface area).

Methods

One hundred and twenty healthy people were selected from a total of 436 Chinese young people based on their answers to a questionnaire. An electrochemical analyzer (NIOX MINO system) was used to measure NNO and FENO. The relationship between NNO, FENO and age, sex, height, weight, BMI, BSA was analyzed using SPSS software.

Results

The values of NNO were normal distributed (mean 273.5 ppb; SD 112.3). The values of FENO were non-normally (Skewed) distributed (median: 14.00 ppb; interquartile range: 7.00 ppb). The obtained NNO values were independent of age, sex, height, weight, BMI and BSA, but were positively correlated to lnFENO (FENO log base e); lnFENO values were also independent of age, height, weight, BMI and BSA, but correlated with NNO and sex.

Conclusions

NNO values positively correlate with lnFENO in healthy people and the levels of each may be predicted by the other. The results of this study are expected to serve as a reference for future studies in China.

The effect of body weight on distal airway function and airway inflammation

BACKGROUND/OBJECTIVES

Obesity is a global health problem that adversely influences the respiratory system. We assessed the effects of body mass index (BMI) on distal airway function and airway inflammation.

SUBJECTS/METHODS

Impulse oscillometry (IOS) as a measure of distal airway function, together with spirometry, were assessed in adults with a range of different BMIs. Airway inflammation was assessed with the fraction of exhaled nitric oxide (FeNO) and participants exhaled at various exhalation flows to determine alveolar and bronchial NO.

RESULTS

In total 34 subjects were enrolled in the study; 19 subjects had a normal BMI (18.50-24.99), whilst 15 subjects were overweight (BMI 25.00-29.99), or obese (BMI ≥30). All subjects had normal spirometry. However, IOS measures of airway resistance (R) at 5Hz, 20Hz and frequency dependence (R_5-20) were elevated in overweight/obese individuals, compared to subjects with a normal BMI (median (interquartile range)); 5Hz: 0.41 (0.37, 0.45) vs. 0.32 (0.30, 0.37)kPa/l/s; 20Hz: 0.34 (0.30, 0.37) vs. 0.30 (0.26, 0.33)kPa/l/s; R_5-20: 0.06 (0.04, 0.11) vs. 0.03 (0.01, 0.05)kPa/l/s; p<0.05), whereas airway reactance at 20Hz was decreased in overweight/obese individuals (20Hz: 0.07 (0.03, 0.09) vs. 0.10 (0.07, 0.13)kPa/l/s, p=0.009; 5Hz: -0.12 (-0.15, -0.10) vs. -0.10 (-0.13, -0.09)kPa/l/s, p=0.07). In contrast, within-breath IOS measures (a sign of expiratory flow limitation) and FeNO inflammatory measures, did not differ between groups (p>0.05).

CONCLUSIONS

Being overweight has significant effects on distal and central airway function as determined by IOS, which is not detected by spirometry. Obesity does not influence airway inflammation as measured by FeNO. IOS is a reliable technique to identify airway abnormalities in the presence of normal spirometry in overweight people.

Fraction of exhaled nitric oxide in healthy Chilean schoolchildren aged 8-15 years

BACKGROUND

The fraction of exhaled nitric oxide (FENO) measured using portable devices is increasingly used in the clinical setting to assess asthmatic children. However, there is little and variable information on the reference values obtained using these devices in healthy children from different populations.

METHODS

190 healthy non-smoker children (8-15 years old) were randomly selected from public schools participating in this study. The objective was to determine FENO reference values for healthy Chilean schoolchildren. Healthy individuals were identified by medical interview and parent questionnaire on the use of asthma medications, and current and past symptoms of asthma, rhinoconjunctivitis and eczema. FENO was measured at schools using a portable device with electrochemical sensor (NIO MINOX). Reference values of FENO were expressed as geometric mean and upper limit of the 95% reference interval (right-sided). The relationship of FENO with gender, age, height, body mass, and other factors was assessed by multiple regression, and the difference between groups was contrasted by ANOVA.

RESULTS

The FENO geometric mean was 15.4ppb with a 95% reference interval upper limit (right-sided), of 27.4ppb (90%CI 25.6-29.2). The 5th and 95th percentiles were 9.0ppb and 28.0ppb, respectively. Height was the only factor significantly associated to FENO (p=0.022). There was no significant difference in mean FENO regarding age, gender, weight, parent reported rhinoconjunctivitis and eczema.

CONCLUSION

This study suggests that FENO values higher than 27ppb are likely to be abnormal and would reflect airway inflammation in children as those in the present study.

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

Purpose

Measurement of the fractional concentration of exhaled nitric oxide (FeNO) is a quantitative, noninvasive, simple, safe method of assessing airway inflammation. While FeNO measurement has been standardized, reference values for elementary school children are scarce. The aim of this study was to establish reference values for FeNO in children.

Methods

FeNO was measured in elementary school children at 6-12 years of age in Seoul, Korea, following American Thoracic Society guidelines and using a chemiluminescence analyzer (NIOX Exhaled Nitric Oxide Monitoring System, Aerocrine, Sweden). A total of 1,252 children completed a modified International Study of Asthma and Allergy in Children (ISAAC) questionnaire; FeNO was measured in 1,063 children according to the protocol and in 808 children defined as healthy controls.

Results

Mean FeNO were 10.32 ppb, 16.58 ppb, and 12.36 ppb in non-atopic, atopic, and all 808 healthy controls, respectively. FeNO was not associated with age and gender. The FeNO reference equations were determined by multiple linear regression analysis, taking into account the variables of age, height, weight, total IgE, eosinophil percent, and bronchial hyper-responsiveness (methacholine PC20). FeNO=0.776+0.003×total IgE+0.340×eosinophil percent; coefficient of determination (R2)=0.084 in the 501 healthy non-atopic controls. FeNO=-18.365+1.536×eosinophil percent, R2=0.183 in the 307 healthy atopic controls; and FeNO=-7.888+0.130×Height+0.004×total IgE+1.233×eosinophil percent, R2=0.209 in the 808 all healthy controls. Eosinophil percent was correlated with FeNO in all healthy controls. FeNO was not associated with BMI.

Conclusion

This study provides reference values for FeNO that can be used to evaluate airway inflammation in elementary school children. Determinants that could most accurately predict FeNO in healthy school-age children were assessed.

Elevated levels of exhaled nitric oxide in patients with anorexia nervosa

BACKGROUND

Nitric oxide (NO) is involved in eating behavior and inflammatory response. Moreover, there is evidence that NO production is altered in patients with anorexia nervosa (AN).

AIM

To assess whether the overproduction of NO in AN can affect NO level in exhaled air.

MATERIALS AND METHODS

Exhaled NO level was studied in 23 girls with AN and compared with that of healthy age- and gender-matched nonatopic controls.

RESULTS

Exhaled NO levels were significantly higher in girls with AN compared with healthy age-matched controls.

CONCLUSIONS

It appears that anorexia nervosa was accompanied by a higher level of exhaled NO, likely resulting from a systemic increase in NO production because of the severe catabolic state.