Exhaled nitric oxide levels in atopic children: relation to specific allergic sensitisation, AHR, and respiratory symptoms

Exhaled Nitric Oxide as Biomarker of Type 2 Diseases

Nitric oxide (NO) is a short-lived gas molecule which has been studied for its role as a signaling molecule in the vasculature and later, in a broader view, as a cellular messenger in many other biological processes such as immunity and inflammation, cell survival, apoptosis, and aging. Fractional exhaled nitric oxide (FeNO) is a convenient, easy-to-obtain, and non-invasive method for assessing active, mainly Th2-driven, airway inflammation, which is sensitive to treatment with standard anti-inflammatory therapy. Consequently, FeNO serves as a valued tool to aid the diagnosis and monitoring of several asthma phenotypes. More recently, FeNO has been evaluated in several other respiratory and/or immunological conditions, including allergic rhinitis, chronic rhinosinusitis with/without nasal polyps, atopic dermatitis, eosinophilic esophagitis, and food allergy. In this review, we aim to provide an extensive overview of the current state of knowledge about FeNO as a biomarker in type 2 inflammation, outlining past and recent data on the application of its measurement in patients affected by a broad variety of atopic/allergic disorders.

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.

Concurrence of elevated FeNO and airway hyperresponsiveness in nonasthmatic adolescents

OBJECTIVES

The aim of this study was to investigate airway responsiveness and eosinophil and neutrophil inflammatory markers in clinically confirmed nonasthmatic adolescents with elevated fractional exhaled nitric oxide (FeNO), a marker of type-2 inflammation in the airways.

METHODOLOGY

A total of 959 subjects from a general population, aged 12 to 15 years, answered a standardised questionnaire and underwent FeNO measurements at a screening visit at school. Adolescents without asthma, who had elevated FeNO (FeNO₁₀₀  > 15 ppb) (n = 19), and control subjects, with low FeNO (FeNO₁₀₀  < 5 ppb) and without reported symptoms of asthma or allergy (n = 28), participated in a follow-up study where FeNO₅₀ , airway responsiveness to methacholine (PD₂₀ ), blood eosinophil counts, and serum neutrophil lipocalin (HNL) and myeloperoxidase (MPO) levels were measured. Questionnaire follow-ups were performed 4 and 16 years later.

RESULTS

Airway responsiveness (PD₂₀ : 6.94 [1.87, 11.39] vs 11.42 [6.33, 59.4] µmol; P < .05) and blood eosinophil counts (0.31 [0.20, 0.44] vs 0.13 [0.1, 0.22] 10⁹ /L; P < .001) (geometric mean [95% CI]) were higher among cases than controls. A significant correlation between blood eosinophils and FeNO was found (rho = 0.41; P = .005). In contrast, serum HNL and MPO were lower in cases than controls (P < .05 both), and there was a negative correlation between HNL and FeNO (r = -0.31; P = .04). At both follow-ups, a higher proportion of subjects reported allergic symptoms compared with baseline (P = .02, P = .01).

CONCLUSIONS

Elevated FeNO in nonasthmatic adolescents was associated with airway hyperresponsiveness, elevated blood eosinophil counts, and lower systemic activation of neutrophils.

Bronchial hyperresponsiveness to mannitol, airway inflammation and Asthma Control Test in atopic asthmatic children

INTRODUCTION

The aim of this study was to evaluate the relationship between airway hyperresponsiveness (AHR) to mannitol and bronchial inflammation measured as exhaled nitric oxide (FeNO) and to assess whether asthma control correlates with AHR to mannitol and FeNO in atopic asthmatic children.

MATERIAL AND METHODS

Allergy evaluation, the mannitol challenge test, FeNO levels and the Asthma Control Test (ACT) questionnaire were assessed in 40 children with intermittent and mild persistent allergic asthma.

RESULTS

All the subjects showed positive AHR to mannitol. Pearson's correlation test revealed a significant inverse correlation between AHR (mannitol PD15) and FeNO (p = 0.020). There was also a significant positive correlation between ACT and PD15 (p = 0.020) and a significant negative correlation between ACT and FeNO levels (p = 0.003). The study population was divided into two groups according to FeNO levels (group A ≥ 16 ppb vs. group B < 16 ppb). In group A mannitol PD15 was significantly lower (p = 0.040) and ACT score values were significantly lower (p = 0.001) compared to group B. In group A, the ACT showed that 13.3% of subjects had well-controlled asthma, 80% had partially controlled asthma and 6.7% had uncontrolled asthma. In group B, the ACT showed that 72% of subjects had well-controlled asthma and 28% had partially controlled asthma.

CONCLUSIONS

Our findings indicate that the degree of AHR to mannitol correlates with the degree of airway inflammation in asthmatic atopic children; moreover, better control of asthma correlates with a lower degree of AHR to both mannitol and FeNO.

Airway hyper-responsiveness to mannitol provides a good evaluation of atopy in childhood asthma

AIM

The relationship between airway hyper-responsiveness (AHR) and atopy has been previously investigated, but there are still some issues to be clarified. The aim of this study was to assess the link between AHR and mannitol and atopy in asthmatic children.

METHODS

We evaluated 44 children with asthma, aged 6-16 years of age, using skin prick tests (SPTs), serum total and specific immunoglobulin E (IgE) levels and the mannitol challenge test (MCT).

RESULTS

We found a good correlation between AHR to mannitol and specific IgE against Dermatophagoides pteronissinus (r = -0.66, p < 0.001) and a weak correlation with specific IgE against dog dander (r = -0.33, p = 0.01) and Aspergillus fumigatus (r = -0.23, p = 0.02). Furthermore, we found a weak correlation between AHR to mannitol and serum total IgE (r = -0.30; p = 0.03), the sum of specific IgE to aeroallergens (r = -0.37, p = 0.01) and the number of positive SPTs (r = -0.31, p = 0.02).

CONCLUSION

Measuring AHR with MCT might provide an accurate evaluation of the degree of atopy in children. The patients with a higher degree of atopy were significantly more reactive to mannitol. In clinical practice, these results indicate that children with asthma who are more atopic may require more intensive treatment strategies to reduce AHR.

Bronchoprovocation tests in asthma: direct versus indirect challenges

PURPOSE OF REVIEW

This review describes different bronchoprovocation tests and their merits in diagnosing asthma.

RECENT FINDINGS

A new indirect challenge test using dry powder mannitol has been made available and has been systematically validated and tested in different populations.

SUMMARY

Airway hyperresponsiveness (AHR) is a characteristic feature of asthma, and its measurement using direct inhalation challenges, particularly with inhaled methacholine or histamine, or indirect challenges using stimuli such as exercise, dry air hyperpnea, distilled water, hypertonic saline and mannitol, and the pharmacological agent adenosine monophosphate is important in establishing a correct diagnosis. Direct challenge tests are sensitive and have a high negative predictive value to exclude asthma. This is particularly true in excluding asthma as a diagnosis in patients with symptoms that suggest asthma, but are caused by another condition. Indirect AHR correlates better with eosinophilic airway inflammation. Therefore, indirect challenge tests are seen as more specific. A newer indirect challenge test that uses a kit containing prepacked capsules of dry powder mannitol in different doses is safe and efficient to use. Indirect challenge tests are superior to direct challenge tests to confirm the presence of asthma.

Establishing IMMULITE® 2000 cut-off values for serum allergen-specific immunoglobulin and exploring their relationship to exhaled nitric oxide

Aim

Paediatric cut-off values for serum allergen-specific IgE (sIgE) using the Siemens IMMULITE® 2000 system to diagnose allergic rhinoconjunctivitis have not been established. We aimed to determine cut-off levels for sIgE for 10 common inhalant allergens and to study the relationship between sIgE, total IgE and fractional exhaled nitric oxide (FE_NO).

Methods

We enrolled 243 schoolchildren, including 164 with allergic rhinoconjunctivitis. Parental interviews, skin prick tests, sIgE, total IgE, FE_NO measurements, spirometry and exercise tests were performed.

Results

Cut-off values with the best combined sensitivity and specificity were above the detection limit of the assay for seven of the ten allergens (0.23–1.1 kU/L). The overall accuracy of the IMMULITE® in detecting allergic rhinoconjunctivitis was good. sIgE was superior to total IgE and FE_NO in predicting allergic rhinoconjunctivitis to timothy, birch, mugwort, cat, dog and house dust mite. FE_NO was elevated in children with allergic rhinoconjunctivitis, irrespective of asthma.

Conclusion

Cut-off values for sIgE were dependent on the allergic phenotype and were above the IMMULITE® detection limit for seven of ten inhalant allergens. Consequently, using the detection limit for sIgE as the decision point would result in over-diagnosing allergic rhinoconjunctivitis. When measuring elevated FE_NO in children, allergic rhinoconjunctivitis should be suspected.

Exhaled nitric oxide measures allergy not symptoms in children with allergic rhinitis in primary care: a prospective cross-sectional and longitudinal cohort study

Background:

Allergic rhinitis (AR) and asthma are both inflammatory diseases and are often associated. Relationships between fractional exhaled nitric oxide (FeNO) and asthma, atopy, and quality of life have been shown.

Aims:

This study aimed to determine whether FeNO in children with AR (n=158) or combined AR and asthma (n=93) was associated with clinical symptoms, house dust mite (HDM)-specific IgE, and rhinitis-specific quality of life, both cross-sectionally and longitudinally.

Methods:

Children with AR aged 6–18 years (n=251) in primary care were assessed for FeNO, nasal symptom scores, asthma symptom scores, quality of life, and HDM-specific IgE at baseline and 2 years later.

Results:

We found similarly elevated FeNO in children with only AR and in those with combined AR and asthma. No correlations were found between FeNO and nasal or asthma symptoms and rhinitis-related quality of life. Longitudinal correlations were strongest for HDM-specific IgE (r=0.91, p<0.0001).

Conclusions:

FeNO was similar in a selected group of children with AR with and without asthma in primary care and was unrelated to symptoms or quality of life in both groups. FeNO is unlikely to be a useful biomarker of the clinical severity of upper or lower airway disease in primary care.

Microbial content of household dust associated with exhaled NO in asthmatic children

Exhaled nitric oxide (eNO) is increasingly used as a non-invasive measure of airway inflammation. Despite this, little information exists regarding the potential effects of indoor microbial components on eNO. We determined the influence of microbial contaminants in house dust and other indoor environmental characteristics on eNO levels in seven-year-olds with and without a physician-diagnosis of asthma. The study included 158 children recruited from a birth cohort study, and 32 were physician-diagnosed as asthmatic. The relationship between eNO levels and exposures to home dust streptomycetes, endotoxin, and molds was investigated. Streptomycetes and endotoxin were analyzed both as loads and concentrations in separate models. Dog, cat, and dust mite allergens also were evaluated. In the multivariate exposure models, high streptomycetes loads and concentrations were significantly associated with a decrease in eNO levels in asthmatic (p<0.001) but not in healthy children. The presence of dog allergen, however, was associated with increased levels of eNO (p=0.001). Dust endotoxin was not significant. The relationship between eNO and indoor exposure to common outdoor molds was u-shaped. In non-asthmatic children, none of the exposure variables was significantly associated with eNO levels. To our knowledge, this is the first study demonstrating a significant association between microbial components in the indoor environment and eNO levels in asthmatic children. This study demonstrates the importance of simultaneously assessing multiple home exposures of asthmatic children to better understand opposing effects. Common components of the indoor Streptomyces community may beneficially influence airway inflammation.

Galangin Abrogates Ovalbumin-Induced Airway Inflammation via Negative Regulation of NF-κB

Persistent activation of nuclear factor κB (NF-κB) has been associated with the development of asthma. Galangin, the active pharmacological ingredient from Alpinia galanga, is reported to have a variety of anti-inflammatory properties in vitro via negative regulation of NF-κB. This study aimed to investigate whether galangin can abrogate ovalbumin- (OVA-) induced airway inflammation by negative regulation of NF-κB. BALB/c mice sensitized and challenged with OVA developed airway hyperresponsiveness (AHR) and inflammation. Galangin dose dependently inhibited OVA-induced increases in total cell counts, eosinophil counts, and interleukin-(IL-) 4, IL-5, and IL-13 levels in bronchoalveolar lavage fluid, and reduced serum level of OVA-specific IgE. Galangin also attenuated AHR, reduced eosinophil infiltration and goblet cell hyperplasia, and reduced expression of inducible nitric oxide synthase and vascular cell adhesion protein-1 (VCAM-1) levels in lung tissue. Additionally, galangin blocked inhibitor of κB degradation, phosphorylation of the p65 subunit of NF-κB, and p65 nuclear translocation from lung tissues of OVA-sensitized mice. Similarly, in normal human airway smooth muscle cells, galangin blocked tumor necrosis factor-α induced p65 nuclear translocation and expression of monocyte chemoattractant protein-1, eotaxin, CXCL10, and VCAM-1. These results suggest that galangin can attenuate ovalbumin-induced airway inflammation by inhibiting the NF-κB pathway.

Fractional exhaled nitric oxide in healthy non-asthmatic 7-year olds and prenatal exposure to polycyclic aromatic hydrocarbons: nested regression analysis

The main goal of the study was to assess possible association between transplacental exposure to genotoxic PAH compounds assessed by the cord blood PAH-DNA adducts and fractional exhaled nitric oxide (FeNO) measured in healthy non-asthmatic children at the age of 7 years. The subjects included the subsample of 89 children who took part in the ongoing population based birth cohort study in Krakow and attended FeNO testing. The effect of transplacental PAH exposure was adjusted for potential confounders, such as maternal allergy and children's specific atopy to common domestic allergens.

RESULTS

FeNO values were significantly elevated in children with higher prenatal PAH exposure (gmean = 7.7 ppb; 95% CI: 5.8-10.2 ppb) compared with those at low exposure level (gmean = 3.8 ppb; 95% CI: 2.3-6.3) (P = 0.011). Children with maternal allergy had also significantly higher mean FeNO values (gmean = 13.7 ppb, 95% CI: 8.8-21.4 ppb) compared with the subjects whose mothers denied allergy (gmean = 5.6 ppb, 95% CI: 4.3-7.3 ppb) (P = 0.012). Similarly, FeNO values in atopic children were higher (gmean = 11.2 ppb; 95% CI: 3.8-32.8 ppb) than in non-atopic individuals (gmean = 6.0 ppb; 95% CI: 4.7-7.7 ppb, P = 0.079). The results of the nested multivariable linear regression analysis showed that both maternal allergy and sensitization of children to domestic aeroallergens jointly explained 10.4% of FeNO variance, however, the additional 10.9% was determined by prenatal PAH exposure.

CONCLUSION

FeNO is more than a marker useful for screening atopy or symptomatic bronchial inflammation and may also be a proxy for cytokine deregulation and "allergic response" phenotype possibly established in fetal period due to transplacental PAH exposure. Preliminary results of our study should encourage more studies on intrauterine PAH exposure and later respiratory symptoms.

Is FENO50 useful diagnostic tool in suspected asthma?

BACKGROUND

Asthma diagnosis is based on the presence of symptoms and the demonstration of airflow variability. Airway inflammation measured by fractional exhaled nitric oxide, measured at a flow rate of 50 ml/s (FE(NO50)) remains a controversial diagnostic tool.

AIM

To assess the ability of FE(NO50) to identify bronchial hyperresponsiveness (BHR) to methacholine (provocative concentration of methacholine causing a 20% fall in FEV(1); PC20M ≤ 16 mg/ml) and to establish whether or not symptoms relate to FE(NO50) and PC20M in patients with no demonstrated reversibility to β(2) -agonist.

METHODS

We conducted a prospective study on 174 steroid naive patients with respiratory symptoms, forced expiratory volume in 1 s (FEV(1) ) ≥ 70% predicted and no demonstrated reversibility to β(2) -agonist. Patients answered to a standardised symptom questionnaire and underwent FE(NO50) and methacholine challenge. Receiver-operating characteristic (ROC) curve and logistic regression analysis assessed the relationship between PC20M and FE(NO50) , taking into account covariates (smoking, atopy, age, gender and FEV(1)).

RESULTS

A total of 82 patients had a PC20M ≤ 16 mg/ml and had significantly higher FE(NO50) (19 ppb vs. 15 ppb; p < 0.05). By constructing ROC curve, we found that FE(NO50) cut-off value of 34 ppb was able to identify not only BHR with high specificity (95%) and positive predictive value (88%) but low sensitivity (35%) and negative predictive value (62%). When combining all variables into the logistic model, FE(NO50) (p = 0.0011) and FEV(1) (p < 0.0001) were independent predictors of BHR whereas age, gender, smoking and atopy had no influence. The presence of diurnal and nocturnal wheezing was associated with raised FE(NO50) (p < 0.001 and p < 0.05, respectively).

CONCLUSION

The value of FE(NO50) > 34 ppb has high predictive value of PC20M < 16 in patients with suspected asthma in whom bronchodilating test failed to demonstrate reversibility or was not indicated. However, FE(NO50) ≤ 34 ppb does not rule out BHR and should prompt the clinician to ask for a methacholine challenge.

Environmental effects on fractional exhaled nitric oxide in allergic children

Fractional exhaled nitric oxide (FeNO) is a non-invasive marker of airway inflammation in asthma and respiratory allergy. Environmental factors, especially indoor and outdoor air quality, may play an important role in triggering acute exacerbations of respiratory symptoms. The authors have reviewed the literature reporting effects of outdoor and indoor pollutants on FeNO in children. Although the findings are not consistent, urban and industrial pollution-mainly particles (PM(2.5) and PM(10)), nitrogen dioxide (NO(2)), and sulfur dioxide (SO(2))-as well as formaldehyde and electric baseboard heating have been shown to increase FeNO, whilst ozone (O(3)) tends to decrease it. Among children exposed to Environmental Tobacco Smoke (ETS) with a genetic polymorphisms in nitric oxide synthase genes (NOS), a higher nicotine exposure was associated with lower FeNO levels. Finally, although more studies are needed in order to better investigate the effect of gene and environment interactions which may affect the interpretation of FeNO values in the management of children with asthma, clinicians are recommended to consider environmental exposures when taking medical histories for asthma and respiratory allergy. Further research is also needed to assess the effects of remedial interventions aimed at reducing/abating environmental exposures in asthmatic/allergic patients.

[Diagnostic value of exhaled nitric oxide measurement in mild asthma]

OBJECTIVES

To assess the diagnostic value of fractional exhaled nitric oxide (FE(NO)) in mild asthma.

MATERIAL AND METHODS

Cross-sectional descriptive study in a group of patients with no history of respiratory or allergic illness (control group) and a group of patients with a history of mild asthma with no baseline treatment (asthma group), both aged 6 to 14 years. The following examinations were performed: measurement of FE(NO) using the portable NIOX MINO(®) device, allergy tests and spirometry. Repeatability of paired FE(NO) measurements was estimated with the intraclass correlation coefficient, the repeatability coefficient and the variation coefficient. The diagnostic value was assessed with the sensitivity, specificity, area under the ROC curve and positive likelihood ratio (LR+) for each cut-off point.

RESULTS

Eighty-seven patients were included in the control group and 57 in the asthma group. The mean FE(NO) value was 12.1 ppb (SD 13.5) in the control group and 42.9 ppb (SD 24.5) in asthmatics (P<.001). The intraclass correlation coefficient was 0.98 (95% CI: 0.96-0.99) and of 0.97 (95% CI: 0.92-0.99) in controls and asthmatics, respectively. The repeatability coefficient was 5.5 in controls and 9.2 in asthmatic children, and the median variation coefficient was 8.3% and 6.1%. The optimal cut-off value for FE(NO) was 19 ppb (sensitivity and specificity were 91.4% and 87.2%, respectively). The area under the ROC curve was 0.93 (95% CI: 0.88-0.97) (P<.001) and the LR+ was 7.1. Subclinical sensitisation to pneumoallergens accounted for most false positive cases.

CONCLUSIONS

The determination of FE(NO) with NIOX MINO(®) has an adequate repeatability, especially for healthy patients. For asthmatic patients we recommend determining the average of two measurements. The test has a high diagnostic value in mild asthma. Subclinical sensitisation to pneumoallergens can cause the FE(NO) value to rise to pathologic levels.

Fluctuation phenotyping based on daily fraction of exhaled nitric oxide values in asthmatic children

BACKGROUND

Fraction of exhaled nitric oxide (Feno), a marker of airway inflammation, has been proposed to be useful for asthma management, but conclusions are inconsistent. This might be due to the failure of mean statistics to characterize individual variability in Feno values, which is possibly a better indicator of asthma control than single measurements.

OBJECTIVE

We characterized fractal fluctuations in daily Feno values over time and the relationship between Feno values and symptom scores. We investigated whether these are associated with asthma severity, control, and exacerbation risk.

METHODS

Daily Feno values and symptom scores over 192 days in 41 atopic asthmatic children from the Childhood Asthma Respiratory Inflammatory Status Monitoring study were analyzed. Two methods of time-series analysis were used: detrended fluctuation analysis to quantify fractal patterns in fluctuations in daily Feno values (α value) and cross-correlation to quantify the strength of the relationship between daily Feno values and symptom scores. The associations of α values and cross-correlation with markers of asthma severity and control were assessed by means of regression analysis.

RESULTS

Daily fluctuations in Feno values exhibited fractal-type long-range correlations. Those subjects receiving higher doses of inhaled corticosteroids at study entry had a significantly lower α value, corresponding to more random fluctuations in Feno values in those with greater inhaled corticosteroid need. The cross-correlation between Feno values and symptom scores was significantly higher in those subjects who had exacerbations.

CONCLUSIONS

Fluctuation in Feno values and their cross-correlation to symptom scores contains information on asthma severity and control. Methods that quantify the complexity of asthma over time might assist in identifying asthmatic subjects with concordance between eosinophilic inflammation and symptoms and thus increased exacerbation risk.

Determinants of exhaled nitric oxide levels (FeNO) in childhood atopic asthma: evidence for neonatal respiratory distress as a factor associated with low FeNO levels

BACKGROUND

In allergic asthmatic children exhaled nitric oxide (FeNO) levels are related to eosinophilic inflammation by correlation analysis. Whether FeNO can be modified by factors potentially influencing the natural history of asthma in early life is not known.

OBJECTIVE

To evaluate the frequency of anamnestic factors influencing the natural history of asthma and to identify potential determinants for elevated or low FeNO levels by multivariate analysis.

METHODS

One hundred seventy-one children with mild-moderate asthma were stratified according to their FeNO levels into three groups: low (<20 ppb), mid (20-40 ppb), and high (>40 ppb). The frequency of nine anamnestic factors together with indices of allergic sensitization (total and allergen-specific immunoglobulin E [IgE], blood eosinophil counts) and of airflow limitation (forced expiratory volume in one second [FEV(1)]% predicted) were evaluated. Results. Among factors related to the patient history, neonatal respiratory distress was reported only in children with low FeNO levels, whereas this factor was never reported in children with mid-to-high FeNO levels (p = .008). As compared with low FeNO group, mid and high FeNO groups showed higher eosinophil counts and a tendency to have lower FEV(1) values. By multivariate analysis, four factors (eosinophils >300 cells/mm(3), cat-specific IgE, house dust mites [HDM]-specific IgE, FEV(1) ≤ 86% predicted) turned out to be significantly associated with mid-high FeNO levels and two factors (eosinophils >600 cells/mm(3), total IgE >355 kU/L) with high FeNO levels.

CONCLUSIONS

Besides confirming the well-known tight association between blood eosinophilia and/or allergic sensitization and FeNO, these data provide new evidence for neonatal respiratory distress as potential factor associated with low FeNO levels in childhood atopic asthma.

FeNO as a Marker of Airways Inflammation: The Possible Implications in Childhood Asthma Management

The aim of this study was to verify FeNO usefulness, as a marker of bronchial inflammation, in the assessment of therapeutic management of childhood asthma. We performed a prospective 1-year randomized clinical trial evaluating two groups of 32 children with allergic asthma: "GINA group", in which therapy was assessed only by GINA guidelines and "FeNO group", who followed a therapeutic program assessed also on FeNO measurements. Asthma Severity score (ASs), Asthma Exacerbation Frequency (AEf), and Asthma Therapy score (ATs) were evaluated at the start of the study (T1), 6 months (T2), and 1 year after (T3). ASs and AEf significantly decreased only in the FeNO group at times T2 and T3 (p[T1-T2] = 0.0001, and p[T1-T3] = 0.01; p[T1-T2] = 0.0001; and p[T1-T3] < 0.0001, resp.). After six months of follow-up, we found a significant increase of patients under inhaled corticosteroid and/or antileukotrienes in the GINA group compared to the FeNO group (P = .02). Our data show that FeNO measurements, might be a very useful additional parameter for management of asthma, which is able to avoid unnecessary inhaled corticosteroid and antileukotrienes therapies, however, mantaining a treatment sufficient to obtain a meaningful improvement of asthma.

Effect of natural seasonal pollen exposure and repeated nasal allergen provocations on elevation of exhaled nitric oxide

BACKGROUND

Exhaled nitric oxide (FENO) is a marker for allergic airway inflammation. We wondered whether in patients with intermittent allergic rhinitis only (i) natural pollen exposure and (ii) artificial pollen exposure by repeated nasal allergen provocations may lead to an elevation of FENO.

METHODS

In two prospective studies, we compared the FENO of nonatopic controls with the FENO of nonasthmatic individuals with mild intermittent rhinitis to tree and/or grass pollen. Study I: 13 atopic individuals and seven controls had measurements of FENO, blood eosinophils and eosinophilic cationic protein (ECP) before, during and after pollen season. Study II: 16 atopic individuals and 12 controls had nasal allergen provocations on four following days out of pollen season, with daily measurements of FENO before, 2 and 6 h after provocation, and determination of blood eosinophils, ECP and FEV1 at baseline, on days 5 and 10-12.

RESULTS

Natural pollen exposure (study I) caused a significant elevation of FENO in allergic individuals. Nasal allergen provocations (study II) did not elicit a statistically significant rise neither of FENO nor of blood eosinophils between baseline and day 5. However, a subgroup of four individuals with a rise of blood eosinophils during nasal allergen provocations showed also a rise of FENO.

CONCLUSIONS

We suppose that in allergic rhinitis a concomitant reaction of the bronchial system is dependent on a strong local inflammation leading to a generalized immune stimulation.

Exhaled nitric oxide in evaluation of young adults with chronic cough

BACKGROUND

Bronchial asthma (A) is frequently diagnosed in patients with chronic cough. The study was conducted to determine whether an evaluation of fractional exhaled nitric oxide (FeNO) concentration can be used as a screening test for asthma in young adults with chronic cough (CCP).

METHODS

The study was performed on 540 (mean age 26.5; range 18-45 years), nonsmoking young CCP. All patients had resting spirometry within normal limits and no abnormalities on chest radiographs. Skin prick tests with common aeroallergens, bronchial provocation challenge with histamine, and evaluation of FeNO concentration were performed in all patients. One hundred healthy, nonsmoking, nonatopic subjects were used as control subjects (HC).

RESULTS

Asthma (A) was diagnosed in 178 CCP (32.96%). Other frequent diagnoses included rhinitis/sinusitis (R) and gastroesophageal reflux (GERD). The median FeNO concentration in A (86 ppb; 95% CI 72 to 94,5 ppb) was significantly greater than in R (37 ppb; 95% CI 35,6 to 42,9 ppb; p < 0.0001), GERD (14,8 ppb; 95%CI 13.3 to 16.2 ppb; p < 0.0001), or in HC (13 ppb; 95%CI 11 to 15 ppb; p < 0.0001). Significant correlation was found between log(FeNO) and bronchial reactivity expressed as log(PC20) (r = -0.529; 95%CI -0.616 to -0.429; p < 0.0001), but even stronger correlation was demonstrated between log(FeNO) and peripheral blood eosinophilia (r = 0.757; 95%CI 0.717 to 0.792). Receiver Operator Characteristic (ROC) curve analysis revealed that CCP can be screened for A by measuring FeNO concentration. Using 40 ppb as a cut-off value for the FeNO concentration, the specificity 82.6% and sensitivity 88.3% can be achieved.

CONCLUSION

In clinical practice, assessment of FeNO concentration can be used as a screening test for asthma in young adults who have chronic cough.

Relation between inflammation and symptoms in asthma

Asthma symptoms are the main reason for healthcare utilization and are a fundamental parameter for the evaluation of asthma control. Currently, asthma is defined as a chronic inflammatory disease. A French expert group studied the association between inflammation and asthma symptoms by carrying out a critical review of the international literature. Uncontrolled asthmatics have an increased number of polynuclear eosinophils in the induced sputum and an increased production of exhaled NO. Control by anti-inflammatory treatment is accompanied by a reduction in bronchial eosinophilia and exhaled NO. Asthma symptoms are the result of complex mechanisms and many factors modify their perception. Experimental data suggest that there is a relationship between the perception of symptoms and eosinophilic inflammation and that inhaled corticoid therapy improves this perception. Although they are still not applicable in routine practice, follow-up strategies based on the evaluation of inflammation are thought to be more effective in reducing exacerbations than those usually recommended based on symptoms and sequential analysis of respiratory function. Inhaled corticosteroid therapy is the reference disease-modifying therapy for persistent asthma. Recent studies demonstrated that adjustment of anti-inflammatory treatment based on symptoms is an effective strategy to prevent exacerbations and reduce the total number of doses of inhaled corticosteroids.

[The relationship between inflammation and symptoms in asthma]

In asthma, symptoms are the main reason for recourse to healthcare and are a fundamental parameter for the evaluation of asthma control. Currently, asthma is defined as a chronic inflammatory disease. Uncontrolled asthmatics have an increased number of eosinophils in induced sputum and an increased production of exhaled NO. Control by anti-inflammatory treatment is accompanied by a reduction in bronchial eosinophilia and exhaled NO. Asthma symptoms are the result of complex mechanisms and many factors modify their perception. Experimental data suggests that there is a relationship between the perception of symptoms and eosinophilic inflammation, and that inhaled corticoid therapy improves this perception. Although they are still not applicable in routine practice, follow-up strategies based on the evaluation of inflammation are thought to be more effective in reducing exacerbations than those usually recommended based on retrospective evaluation of symptoms and sequential analysis of respiratory function. Inhaled corticosteroid therapy is the reference maintenance therapy for persistent asthma and adjustment of anti-inflammatory treatment based on symptoms is an effective strategy to prevent exacerbations and reduce the total dose of inhaled corticosteroids. A French expert group has undertaken a study of the association between inflammation and asthma symptoms by carrying out a critical review of the international literature.

Exhaled nitric oxide and respiratory symptoms in a community sample of school aged children

OBJECTIVE

To test the association between reported allergy and allergic diseases, respiratory symptoms, and the fractional concentration of exhaled nitric oxide (FeNO), in a community sample of school aged children.

METHODOLOGY

We administered a respiratory questionnaire and measured FeNO in a cross-sectional study of 1,135 children.

RESULTS

FeNO was significantly greater in children with reported asthma (20.3 (standard deviation (SD) 21.3) parts per billion (ppb)) or allergies (18.1 (SD 18.0) ppb) than in healthy children (14.0 (SD 13.4) ppb). It was greater in children with asthma and reported allergies (22.8 (SD 23.6) ppb), than in children with asthma but no allergies (15.8 (SD 15.6) ppb) (overall P-value between disease groups = 0.002). FeNO was not related to respiratory symptoms in healthy children. Eczema was associated with an elevated FeNO concentration, even in the absence of respiratory symptoms. Some children with reported allergies but not asthma who had respiratory symptoms suggestive of asthma had elevated FeNO concentrations, and the proportion of healthy children with reported bronchitis or pneumonia in the past year who had an abnormally high FeNO concentration was significantly elevated.

CONCLUSIONS

In a community sample of children, FeNO concentrations appear to reflect allergic conditions, including allergic asthma, reported allergies, and eczema, rather than just asthma, particularly since asthma in children may be non-allergic. FeNO is similarly elevated in school aged children with reported asthma or reported allergies. FeNO is higher in children with asthma and allergies than in children with asthma alone. However, an elevated FeNO may help alert the clinician to the possibility of undiagnosed asthma.

Factors that influence exhaled nitric oxide in Italian schoolchildren

BACKGROUND

Conflicting results exist about the meaning of exhaled nitric oxide (eNO) in epidemiologic studies, mainly because of the numerous factors that may affect the measurement.

OBJECTIVES

To evaluate the role of the factors that influence eNO levels in a sample of schoolchildren with or without respiratory diseases. We studied 335 schoolchildren, ages 10 to 16 years, from 8 schools in Palermo, Italy. After a respiratory questionnaire was completed, spirometry, skin tests, and eNO measurements were performed.

RESULTS

Among 335 children, 13.7% reported symptoms of bronchial asthma, 46.9% reported symptoms of rhinitis, and 39.4% were asymptomatic. The ratio of forced expiratory volume in 1 second to forced vital capacity was 87.6% (SD, 6.4%) in the bronchial asthma group, 90.6% (SD, 5.0%) in the rhinitis group, and 90.4% (SD, 5.1%) in the asymptomatic group (P < .002). Atopic children constituted 52.2% of the bronchial asthma group, 40.1% of the rhinitis group, and 28.8% of the asymptomatic group. Among atopic children, 102 (82%) had a positive skin test result for Dermatophagoides. Median eNO was 12.6 ppb in nonatopic children and 21.2 ppb in atopic children (P < .001, by Mann-Whitney U test). Among asymptomatic children, atopic children had significantly higher eNO levels than did nonatopic children (P < .001). In nonatopic children, no difference was found in log transformation eNO among healthy, rhinitic, or asthmatic children. Log transformation eNO increased with the number of positive skin test results (P < .001). Atopy, asthma, male sex, and indoor allergens were predictors of increased eNO in a logistic model.

CONCLUSIONS

Atopy (in particular, sensitization to indoor and perennial allergens) is strongly associated with higher eNO levels. Such association is enhanced by asthma.

Equally elevated concentrations of exhaled nitric oxide in nonatopic and low-sensitized atopic asthmatics

BACKGROUND

Some studies show concentrations of exhaled nitric oxide (FENO) in nonatopic asthma and in healthy subjects to be similar, but include asthmatics on inhaled steroids, which is likely to interfere with the results.

AIM

Comparison of FENO between nonatopic asthmatics, low-sensitized and high-sensitized atopic asthmatics, and healthy controls.

METHODS

We studied 85 non-smoking, steroid-naive young men with recently diagnosed symptomatic asthma and 10 healthy controls. FENO was measured according to European Respiratory Society Guidelines. In skin prick tests of 13 common aeroallergens, subjects with a total sum of prick wheals 3-10mm were regarded as low-sensitized and those with >10mm, as high-sensitized. Flow-volume spirometry, standardized histamine challenge, and an exercise test were also carried out.

RESULTS

Prick tests revealed 14 subjects to be nonatopic and 71 atopic. In high-sensitized subjects with atopic asthma, the FENO median (25-75 quartiles) was significantly higher, 34.9 (21.3-53.8) parts per billion (ppb), than in subjects with nonatopic asthma, 15.2 (9.7-24.7)ppb (p<0.001), both being significantly higher than in healthy controls, 6.6 (5.2-8.5)ppb (p<0.001). FENO levels were similar in nonatopic and in low-sensitized atopic asthmatics, with no difference between them in bronchial responsiveness to histamine and exercise.

CONCLUSION

Among steroid-naive young male asthmatics, FENO was equally elevated in nonatopic asthma and in low-sensitized atopic asthma but lower than in those with high-sensitized atopic asthma. These differences in FENO between asthma groups parallel the differences in airway function disturbance in terms of responsiveness to histamine or exercise.

Expired nitric oxide and airway reactivity in infants at risk for asthma

BACKGROUND

Family histories of atopy, as well as histories of atopic dermatitis and food allergy, are important risk factors for an infant to have asthma. Although atopic sensitization appears to contribute to the development of asthma, it is unclear when the airways become involved with the atopic process and whether airway function relates to the atopic characteristics of the infant.

OBJECTIVE

We sought to evaluate whether atopic infants without prior episodes of wheezing have increased expired nitric oxide (eNO) levels and heightened airway reactivity.

METHODS

Infants with eczema were recruited, and atopic status was defined by specific IgE levels to foods or aeroallergens and total IgE levels. eNO, forced expiratory flow at 75% exhaled volume (FEF(75)), and airway reactivity to inhaled methacholine were measured in sedated infants. Airway reactivity was quantified by using the provocative concentration to decrease FEF(75) by 30%.

RESULTS

Median age for the 114 infants evaluated was 10.7 months (range, 2.6-19.1 months). Infants sensitized to egg or milk compared with infants sensitized to neither egg nor milk had lower flows (FEF(75): 336 vs 285 mL/s, P < .003) and lower lnPC(30) (mg/mL) provocative concentrations to decrease FEF(75) by 30% (-0.6 vs -1.2, P < .02) but no difference in eNO levels. Infants with total serum IgE levels of greater than 20 IU/mL had higher eNO levels compared with infants with IgE levels of 20 IU/mL or less (14.6 vs 11.2 ppb, P < .023) but no difference in forced flows or airway reactivity.

CONCLUSIONS

Our findings suggest that atopic characteristics of the infant might be important determinants of the airway physiology of forced expiratory flows, airway reactivity, and eNO.

Variations in exhaled nitric oxide in children with asthma during a 1-week stay in a mountain village sanatorium

Knowing about spontaneous variations in the fractional concentration of exhaled nitric oxide (FE(NO)) could improve monitoring of airway inflammation in asthmatic children. We aimed to assess FE(NO) variations (expiratory flow 50 mL/sec) in subjects maintained in similar environmental conditions. We tested spirometry and FE(NO) in symptom-free asthmatic children (9 corticosteroid-naive, 8 corticosteroid-treated) during a 1-week stay in a countryside sanatorium and in their healthy relatives (n = 12) staying in the immediate neighborhood on summer holiday (total 29 children, M/F:14/15, 5.8-16.8 yrs). Testing sessions were repeated every 12 hours (8:00 am, 8:00 pm) for 2 days and again on day 7. Measurements were defined as reproducible when they agreed with an intraclass correlation coefficient (ICC) above 0.60; deviation from mean differences was assessed by the coefficient of repeatability (CR = 2 SD). Lung function remained constant throughout the week in all groups. Baseline FE(NO) levels in corticosteroid-naive asthmatic children tended to decrease at the end of the week (from 13.9 ppb, 95% CI 12.2-19.1 to 9.2 ppb, 95% CI 5.8-15.9, p = 0.057). No differences were found between nocturnal and diurnal FE(NO). Within-session reproducibility for two FE(NO) measurements was high (ICC 0.99 in all groups and CR, 0.9 to 1.3 ppb). Between-session FE(NO) reproducibility at 12 hours and 24 hours was still high for each group but decreased markedly after 6 days in corticosteroid-naive asthmatic children (ICC 0.79 and CR 9.6 ppb at 24 hours vs. ICC 0.13 and CR 20.8 ppb after 6 days), whereas it decreased slightly in corticosteroid-treated asthmatics (from ICC 0.89 and CR 3.1 ppb to ICC 0.88 and CR 3.0 ppb) and healthy children (from ICC 0.79 and CR 4.8 ppb to ICC 0.65 and CR 5.7 ppb). In conclusion, in healthy subjects and in asthmatic children receiving therapy with inhaled corticosteroids (but not in corticosteroid-naive subjects), FE(NO) measurements are reproducible across a week.

The value of FeNO measurement in asthma management: the motion against FeNO to help manage childhood asthma--reality bites

Since exhaled nitric oxide (FeNO) was first demonstrated to be raised in asthmatic patients in the early 1990s, there has been a strong interest in its potential role in the diagnosis and management of asthma. This culminated in 2003 when the US Food and Drug Administration cleared the NIOX nitric oxide analyser for clinical application in patients with asthma. The interest in FeNO is based on the assumptions that FeNO is a marker of asthma and asthma control, and that it reflects eosinophilic airway inflammation. However, the literature remains unconvincing and inconclusive. Furthermore, studies which have management algorithms that include FeNO as a guide to asthma treatment have failed to observe any improvement in asthma control compared with the use of standard asthma guidelines. At present, the cost of including FeNO in management guidelines far outweighs any potential benefits.

The value of exhaled nitric oxide in predicting bronchial hyperresponsiveness in children

Reduced attention span and motor skills in children limit the practicability of bronchial provocation tests. To assess exhaled nitric oxide (FeNO) as a surrogate for bronchial hyperresponsiveness (BHR) in children with possible reactive airway disease, FeNO was measured using the single-breath method in 169 successive outpatients 11 +/- 5 years of age before lung function testing and subsequent bronchial provocation by exercise (n = 165) and methacholine (n = 134). Baseline forced expiratory volume in 1 second (FEV(1)) less than 80% of predicted and/or BHR were seen in 59%. FeNO correlated weakly with PD(20) to methacholine (r = -0.24, p < 0.05), but not with the change in FEV(1) due to exercise-induced bronchoconstriction (EIB) (r = 0.1, p > 0.05). The negative predictive value of FeNO less than 10 ppb for EIB was 94%, but overall accuracy for predicting BHR was low. Measurement of FeNO is not a substitute for bronchial provocation in children.

Exhaled nitric oxide: interactions between asthma, hayfever, and atopic dermatitis in school children

BACKGROUND

Clinicians frequently rely on reported symptoms and basic pulmonary function testing to assess asthma prevalence in the community. However, given that spirometry results are often normal for asthmatic children and the fact that there is no equivalent word for 'wheeze' in languages other than English, the assessment of asthma prevalence can be troublesome.

OBJECTIVE

To evaluate in a population based setting, whether FeNO as a non-invasive marker, contributes to the detection of asthma.

METHODS

This cross-sectional study was carried out on primary school children from Northern and Southern Tyrol. FeNO measurements were made using the online single breath technique prior to spirometry. Symptom status including asthma, hayfever and atopic dermatitis was determined by the ISAAC questionnaire.

RESULTS

Six hundred and forty-four Tyrolean children aged 8-10 years participated. In terms of FEV1 % predicted, the asthma and hayfever group had significantly lower values compared to the asymptomatic group, the hayfever only, and the atopic dermatitis only groups. For FeNO, participants with asthma and hayfever, asthma and atopic dermatitis, and hayfever only recorded significantly greater FeNO values when compared to the asymptomatic group. Moreover, the asthma and atopic dermatitis group recorded significantly greater FeNO when compared to the asthma only group. Multivariate regression revealed that asthma had a small significant inverse association with FEV1 % predicted for the individual model and when combined with hayfever. For FeNO, each of the individual and combined model analyses achieved significance.

CONCLUSION

Although FeNO appears to be influenced by asthma, the presence of other atopic conditions confounds the relationship. Elevated levels of FeNO do not distinguish between asthma and other atopic conditions. Therefore, FeNO does not contribute to the detection of asthma in the community.

CLINICAL IMPLICATION

FeNO is not a valuable tool for the detection of asthma in the community as it is confounded by other atopic conditions.

Effect of inhaled steroid therapy on exhaled nitric oxide and bronchial responsiveness in children with asthma

Inhaled steroid therapy is reported to reduce the level of exhaled nitric oxide (eNO), but the effects of inhaled corticosteroids (ICS) on bronchial hyperresponsiveness (BHR) have been controversial. The aim of this study was to determine the effects of ICS on the relationship between eNO and BHR. Twenty-six children with asthma were recruited, including 14 children who were receiving ICS (ICS group) and 12 who were not (ICS-naive group). The fractional exhaled nitric oxide concentration (FE(NO)) was examined by the recommended online method. To evaluate BHR, an acetylcholine challenge test was performed. In the ICS-naive group, FE(NO) was significantly correlated with PC20 (p < 0.05, r = -0.70), but not in the ICS group. In conclusion, FE(NO) was significantly correlated with BHR in the ICS-naive group, but this relationship was not present in the ICS group. Our results suggest that the use of ICS should be taken into consideration when evaluating the relation between BHR and airway inflammation.

Elevated exhaled nitric oxide in newborns of atopic mothers precedes respiratory symptoms

RATIONALE

Exhaled nitric oxide (NO) is a well-known marker of established airway inflammation in asthma. Its role in the disease process before the onset of respiratory symptoms remains unclear.

OBJECTIVES

To examine whether elevated NO in newborns with clinically naive airways is associated with subsequent respiratory symptoms in infancy.

METHODS

We measured exhaled NO concentration and output after birth and prospectively assessed respiratory symptoms during infancy in a birth cohort of 164 unselected healthy neonates. We examined a possible association between NO and respiratory symptoms using Poisson regression analysis.

RESULTS

In infants of atopic mothers, elevated NO levels after birth were associated with increased risk of subsequent respiratory symptoms (risk ratio [RR], 7.5; 95% confidence interval [CI], 1.7-32.4 for each nl/s increase in NO output; p = 0.007). Similarly, a positive association between NO and symptoms was seen in infants of smoking mothers (RR, 6.6; 95% CI, 2.3-19.3; p = 0.001), with the strongest association in infants whose mothers had both risk factors (RR, 21.8; 95% CI, 5.8-81.3; p < 0.001).

CONCLUSIONS

The interaction of NO with maternal atopy and smoking on subsequent respiratory symptoms is present early in life. Clinically, noninvasive NO measurements in newborns may prove useful as a new means to identify high-risk infants. Future confirmation of a role for NO metabolism in the evolution of respiratory disease may provide an avenue for preventative strategies.

Environmental exposures and exhaled nitric oxide in children with asthma

OBJECTIVE

To evaluate the relation of environmental factors with exhaled nitric oxide (FENO) concentrations among asthmatic children.

STUDY DESIGN

Cross-sectional analysis of 170 tobacco smoke-exposed children, ages 6 to 12 years, who have doctor-diagnosed asthma using measures of FENO, medication use, and exposures to settled indoor allergens and tobacco smoke.

RESULTS

In multivariable analysis, child's age, uncarpeted flooring, not owning a cat, higher income, dust mite exposure, and being sensitized to any allergens were associated with higher FENO concentrations. Children who were sensitized to indoor allergens had an adjusted geometric mean FENO of 15.4 ppb (95% CI, 13.1, 18.2) compared with 10 ppb (95% CI, 8.2, 12.2) for unsensitized children. There was no statistically significant association of serum cotinine, hair cotinine, or reported corticosteroid therapy with FENO.

CONCLUSIONS

FENO is higher among children who are sensitized to indoor allergens and exposed to dust mites. The results hold promise for the use of FENO as a tool to manage childhood asthma by using both pharmacologic and environmental treatments.

Exhaled nitric oxide in healthy nonatopic school-age children: determinants and height-adjusted reference values

Exhaled nitric oxide (FENO) was proposed as a marker of airway inflammation, but data about FENO in healthy children measured with standardized methods are so far limited. In order to assess the determinants of FENO in healthy children, we investigated a population-based sample of school-age children (n = 276) with a questionnaire, skin-prick tests, spirometry, and the measurement of FENO. The FENO of 114 nonatopic and nonsmoking children considered healthy were analyzed with stepwise multiple regression analysis, which showed significant associations with age, standing height, weight, and body surface area, but not with gender. Height was found to be the best independent variable for the regression equation for FENO, which on average showed an increase in the height range of 120-180 cm from 7 to 14 ppb. In the random sample of children, increased FENO was associated with atopy (odds ratio, 9.0; 95% confidence interval, 3.9-21.1; P < 0.0001), and significantly with allergic rhinitis and atopic dermatitis, but not with asthma. Respiratory symptom-free children with skin-prick test positivity had significantly higher FENO than healthy nonatopic subjects. We conclude that height is the best determinant of FENO in healthy children. Due to the strong effect of atopy, FENO data should not be interpreted without knowing the atopic status of the child. The present reference values of FENO may serve in clinical assessments for measuring airway inflammation in children.

CFTR gene mutations and asthma in the Norwegian Environment and Childhood Asthma study

BACKGROUND

Several candidate genes have been implicated in the etiology of asthma, including the gene coding for the cystic fibrosis transmembrane conductance regulator (CFTR). Mutations in the CFTR gene result in derangements of mucociliary clearance. Homozygotes for CFTR mutations develop cystic fibrosis (CF), a disorder characterized mainly by lung and pancreas disease.

OBJECTIVE

To investigate whether there was an increased frequency of CFTR mutations in asthma patients.

METHODS

Seven hundred and three subjects aged 10-11 years from the environment and childhood asthma (ECA) study were included in the present study. Possible associations between asthma, reduced lung function, bronchial hyperresponsiveness (BHR), and increased or decreased nitrogen oxide (NO) levels (based on structural parental interview, spirometry, PD20 methacholine challenge test and exhaled NO measurements), and the five most common CFTR mutations in Norway (DeltaF508, R117H, R117C, 4005+2T-->C, 394delTT), the modulating polymorphisms IVS8(TG)mTn and the IVS8-5T were investigated.

RESULTS

No association were found between asthma, reduced lung function, BHR or exhaled NO levels and CF heterozygosity. However, the IVS8(TG)11T7 haplotype was associated with normal lung function.

CONCLUSIONS

Our results do not support the hypothesis that CFTR mutations or polymorphisms play a role in the pathogenesis of asthma in children. However, the distribution of Tn(TG)m haplotypes differed between individuals with reduced lung function and individuals with normal lung function.

Correlation of exhaled nitric oxide, spirometry and asthma symptoms

Asthma is the most common chronic disease of childhood. Asthma severity is monitored by spirometry. However, this does not directly measure airway inflammation. Exhaled nitric oxide (FeNO) is a proposed method to measure airway inflammation non-invasively. Previous studies have shown that FeNO correlates with endobronchial biopsies and symptoms in patients with asthma. We monitored daily asthma symptoms compared to monthly spirometry and FeNO. Total monthly symptom scores correlated with both forced expiratory volume at 1 sec (FEV1) and FeNO. FeNO had a strong correlation than FEV1. FeNO and FEV1 were not correlated. We propose that FeNO should be used as an additional monitoring tool for asthma.

Is exhaled nitric oxide measurement a useful clinical test in asthma?

PURPOSE OF REVIEW

Exhaled nitric oxide measurements (FENO) are easy to perform and are repeatable. Given the strong correlations between FENO and bronchial biopsy and induced sputum eosinophilia, as well as airway hyper-responsiveness, FENO may now be advocated as a surrogate for these tests in certain circumstances. They provide the opportunity to assess pathological rather than physiological changes in asthma. This review highlights recent advances in applying this technology to the diagnosis and ongoing assessment of asthma in the clinical and epidemiological settings.

RECENT FINDINGS

Epidemiological data confirm that whereas FENO measurements reflect the presence and severity of airway inflammation, levels do not correlate strongly with symptoms or lung function abnormalities. Although reference values and thresholds for an abnormal test still need to be agreed internationally, there are now sufficient data for clinicians to use the test meaningfully in clinical practice. Studies confirm the relatively high diagnostic accuracy of FENO measurements compared with conventional tests to distinguish asthma from nonasthma. Further, dose-response relationships for changes in FENO with inhaled steroids have been confirmed, and provide the basis for using FENO to assess asthma control and, potentially, to determine antiinflammatory treatment requirements.

SUMMARY

The measurement of FENO is evolving to provide a complementary role alongside existing pulmonary function tests. Further work is required to establish reference values and possibly prediction equations in relation to age and height. Its role in determining optimum steroid requirements in chronic asthma and to identify steroid responsiveness in chronic obstructive pulmonary disease are two important areas for future research.

Exhaled nitric oxide in a population-based study of asthma and allergy in schoolchildren

Exhaled nitric oxide (NO) reflects inflammation in the lower airways and is well adapted for use in children. The aims of this study were to investigate the distribution of the fraction of expired NO (FENO) in school children and to compare FENO and spirometry in relation to the International Study of Asthma and Allergies in Childhood questionnaire. The study was performed in 959 randomly selected 13-14-year-old school children in Uppsala, Sweden. Exhaled NO was measured at an inhalation rate of 0.1 l/s (FENO0.1) and a spirometric test was performed and data from these measurements were related to questionnaire data. Exhaled NO was measured according to American Thoracic Society recommendations, except the use of a mouth wash and an exhalation flow rate of 0.1 l/s. The distribution of the mean FENO0.1 values was skewed, with a preponderance of very low levels and a widespread tail of values ranging up to 102 parts per billion (ppb). Boys exhibited significantly higher mean FENO0.1 values than girls, 5.2 (4.7-5.7) vs 4.4 (4.0-4.8) ppb (geometric mean and 95% CI), P <0.01). Children who reported wheezing in the last year had higher FENO0.1 values than children that had not, 8.5 (7.1-10.2) vs 4.3 (4.0-4.6) ppb, P <0.001). The same association was found to most symptoms indicating hay fever and eczema. In contrast to this, only weak or inconsistent associations were found between asthma and spirometric indices. Exhaled NO levels were found to be independently related to male gender, wheeze and rhinoconjuctivitis but not to current eczema. In conclusion, exhaled NO was closely associated with reported asthma and allergy symptoms whereas spirometric indices such as percent predicted forced expiratory volume in 1 s were not. As most asthma cases in a population are mild, the findings suggest that exhaled NO is a sensitive marker of asthma and allergy.

Measuring exhaled nitric oxide levels in adults: the importance of atopy and airway responsiveness

BACKGROUND

Raised exhaled nitric oxide (Feno) levels have been associated with asthma. However, we have found that in children, Feno was increased in atopic children with increased airway responsiveness (AR), and this was independent of a diagnosis of asthma.

STUDY OBJECTIVES

The current study was designed to test the hypothesis that in adults there is no association between Feno and asthma after controlling for atopy and AR.

MEASUREMENTS

One hundred fifteen adults (77 women; mean age, 41 years) underwent an assessment that included Feno measurements, spirometry, skin-prick testing, blood eosinophil count, and inhaled histamine challenge (results are expressed as a dose-response slope [DRS]).

RESULTS

When only atopic individuals were considered (n = 73), Feno was positively associated with the DRS (p = 0.003), male gender (0.02), and negatively associated with current smoking (p = 0.09). Only male gender (p = 0.03) was associated with Feno among nonatopic individuals (n = 36). In multivariate analysis, there was no association between Feno and current asthma, current wheeze, or asthma ever.

CONCLUSIONS

We conclude that in adult subjects, elevated Feno measurements are associated with a phenotype characterized by atopy and increased AR regardless of the presence of asthma or asthma-like symptoms.

[The measurement of exhaled nitric oxide, a new tool in the management of asthma?]

A GOOD DIAGNOSTIC TEST FOR ASTHMA: Chronic airway inflammation, main feature of asthma, can be assessed by measuring the exhaled nitric oxide (NO) level. Measurement of NO is standardized, non-invasive and easy to use in both children and adults. Studies have shown that it is a good diagnostic test for asthma when NO is high. However, other conditions or pathologies must be searched for because they may influence the results. ITS PLACE IN TREATMENT: Although exhaled NO helps to characterise the patients with asthma, other studies are required to show that it can help to improve the follow-up of such patients. Nevertheless, this tool has not yet been validated in the daily treatment of asthma and further research is still ongoing.

Exhaled nitric oxide in relation to the clinical features of childhood asthma

BACKGROUND

Exhaled nitric oxide (ENO) has been shown to be a noninvasive marker of eosinophilic inflammation in asthmatic children. Few studies have evaluated the relationship between ENO levels and the clinical features of children with asthma. The aim of this study was to examine children attending a routine asthma clinic and evaluate the relationship between ENO levels and clinical parameters including decision making.

METHODS

Asthmatic children (n= 133, aged 5 to 14 years) attending a hospital asthma clinic were studied. ENO levels were measured and compared between subgroups of subjects according to recent symptoms, asthma control and treatment, and the clinician's decision (blinded to ENO levels) regarding further management.

RESULTS

ENO levels (median [IQR] ppb) were significantly elevated in children who had recent symptoms compared to those without recent symptoms (14.6 [6.5 to 45.3] vs. 6.0 [3.2 to 17.4], difference between medians 8.6, 95% confidence interval [CI] (1.8 to 13.9, p=0.004). ENO levels differed significantly between the controlled and uncontrolled subgroups (8.5 [4.2 to 26.4] vs. 26.4 [5.0 to 62.0], difference between medians 17.9, 95% CI 0.1 to 22.8, p=0.03) and between the three treatment decision subgroups (up, down, or unchanged; p < 0.001).

CONCLUSIONS

ENO levels are strongly related to the clinical features of childhood asthma and the clinical decision making process. To fully evaluate the role of ENO in the clinical management of asthma, this "proof of concept" study paves the way for prospective randomized trials of the inclusion of ENO levels in the decision making process in childhood asthma.

Exhaled nitric oxide and asthma: complex interactions between atopy, airway responsiveness, and symptoms in a community population of children

BACKGROUND

Exhaled nitric oxide (FE(NO)) is raised in asthmatic children, but there are inconsistencies in the relationship between FE(NO) and characteristics of asthma, including atopy, increased airway responsiveness (AR), and airway inflammation. The aim of this study was to investigate the relationship between FE(NO) and asthma, atopy, and increased AR in children.

METHODS

One hundred and fifty five children (79 boys) of mean age 11.5 years underwent an assessment that included FE(NO) measurements, spirometric tests, inhaled histamine challenge, and a skin prick test. Blood was collected for eosinophil count. Current and past asthma like symptoms were determined by questionnaire.

RESULTS

In multiple linear regression analyses FE(NO) was associated with atopy (p<0.001), level of AR (p = 0.005), blood eosinophil count (p = 0.007), and height (p = 0.002) but not with physician diagnosed asthma (p = 0.1) or reported wheeze in the last 12 months (p = 0.5). Separate regression models were conducted for atopic and non-atopic children and associations between FE(NO) and AR, blood eosinophils and height were only evident in atopic children. Exhaled NO was raised in children with a combination of atopy and increased AR independent of symptoms.

CONCLUSION

Raised FE(NO) seems to be associated with an underlying mechanism linking atopy and AR but not necessarily respiratory symptoms.

Total and allergen-specific IgE levels in serum reflect blood eosinophilia and fractional exhaled nitric oxide concentrations but not pulmonary functions in allergic asthmatic children sensitized to house dust mites

Although elevated levels of serum immunoglobulin E (IgE) are considered the hallmark of atopic diseases, their clinical value in evaluating subjects with allergic disorders is under debate. To evaluate possible relationships between serum IgE levels and a variety of clinical parameters, 83 mild asthmatic children [10.98-year-old (2.95)], sensitized to house dust mites (HDM) Dermatophagoides pteronyssinus (Dp) or D. farinae (Df), were enrolled. As compared with normal control reference values detected in our laboratory, children with allergic asthma had higher blood eosinophil counts (expressed both as percentage and as absolute number) and higher fractional exhaled nitric oxide (FeNO) levels but similar values in pulmonary function parameters. In the allergic asthmatic population, serum levels of total, Dp-specific or Df-specific IgE correlated positively with eosinophil counts (Rho > or = 0.30, p < 0.01, each correlation) and FeNO levels (Rho > or = 0.33, p < 0.01, each correlation) but not with pulmonary function parameters (p > 0.1, each correlation). Finally, significant correlations, although moderate, were found in the allergic asthmatic population between eosinophil counts and FeNO levels (Rho > or = 0.42, p < 0.001, each correlation). Thus, in atopic children sensitized to HDM with mild intermittent asthma, IgE levels in blood appear to reflect systemic (blood eosinophils) and organ-specific (FeNO) markers of allergic inflammation but not pulmonary volumes or the degree of airflow limitation.

Comparisons of the complementary effect on exhaled nitric oxide of salmeterol vs montelukast in asthmatic children taking regular inhaled budesonide

BACKGROUND

Inhaled, long-acting beta2-agonists or antileukotrienes are alternatives as add-on therapy for asthmatic children taking regular inhaled steroids. Any complementary effects would be relevant to the choice between these alternatives. Exhaled nitric oxide (FeNO) may reflect these effects.

OBJECTIVE

To compare the control of FeNO provided by salmeterol or montelukast add-on therapy in asthmatic children undergoing regular maintenance treatment with a daily dose of 400 microg of budesonide.

METHODS

The study included children with increased FeNO despite regular treatment with budesonide, 400 microg/d, and normal lung function. Montelukast, 5 mg/d, salmeterol, 50 microg twice daily, or placebo was compared as add-on therapy to budesonide, 400 microg, in a randomized, double-blind, double-dummy, crossover study.

RESULTS

Twenty-two children completed the trial. The geometric mean FeNO level was 20 ppb (95% confidence interval [CI], 15-27 ppb) after salmeterol, which was significantly higher than after montelukast (mean, 15 ppb; 95% CI, 11-18 ppb; P = 0.002) and placebo (mean, 15 ppb; 95% CI, 10-21 ppb; P = 0.03). There was no difference in FeNO between the montelukast and placebo groups. Mean forced expiratory volume in 1 second (FEV1) was significantly increased after salmeterol (mean, 2.63 L; 95% CI, 2.34-2.91 L) compared with placebo (mean, 2.48 L; 95% CI, 2.19-2.77 L). Montelukast (mean, 2.57 L; 95% CI, 2.33-2.80 L) was no different than placebo.

CONCLUSIONS

The FeNO levels were significantly higher after salmeterol add-on treatment compared with both placebo and montelukast add-on treatment. Salmeterol significantly improved lung function (FEV1) compared with placebo and nonsignificantly compared with montelukast. Montelukast failed to reduce FeNO and improve lung function compared with placebo in this group of children taking regular budesonide, 400 microg.

Relationship among pulmonary function, bronchial reactivity, and exhaled nitric oxide in a large group of asthmatic patients

BACKGROUND

Bronchial reactivity and exhaled nitric oxide (eNO) are not often used to monitor control and severity of asthma in clinical practice.

OBJECTIVE

To evaluate the relationship among different physiologic measures (pulmonary function, nonspecific bronchial reactivity, and eNO) in asthmatic patients.

METHODS

Cross-sectional, hospital-based study conducted in patients with varied asthma severity.

RESULTS

A total of 392 patients participated in the study. There was no difference in eNO levels between patients taking inhaled corticosteroids (ICS group) and patients not receiving inhaled corticosteroids (NICS group). However, the percentage of predicted forced expiratory volume in 1 second (FEV1) and the provocative dose of methacholine causing a 20% decrease in FEV1 were significantly lower in the ICS group compared with the NICS group (mean, 83.2%; 95% confidence interval [CI], 80.4%-86.0%; vs mean, 94.1%; 95% CI, 91.1%-97.1%; P = .001; and geometric mean, 0.32 mg; 95% CI, 0.23-0.45 mg; vs geometric mean, 0.58 mg; 95% CI, 0.42-0.81 mg; P = .01; respectively). Patients with more severe bronchial hyperresponsiveness had a lower percentage of predicted FEV1 values (P < .001) and levels of eNO were significantly increased with increasing bronchial hyperresponsiveness (P < .001). There was no relationship between the percentage of predicted FEV1 and eNO. Atopic patients had significantly higher eNO levels than nonatopic patients (geometric mean, 11.21 ppb; 95% CI, 10.07-12.49 ppb; vs geometric mean, 7.76 ppb; 95% CI, 6.11-9.85 ppb; P = .006; respectively).

CONCLUSIONS

eNO values are not related to the degree of airway obstruction but are related to airway reactivity and atopic status independent of inhaled corticosteroid use. Higher values of eNO are seen with increased airway reactivity.

Nitric oxide in allergic airway inflammation

PURPOSE OF REVIEW

Exhaled nitric oxide has been proposed as a useful noninvasive marker of airway inflammation in asthma. Great efforts have been made to standardize the methodology for exhaled nitric oxide measurement in both children and adults. As a consequence there is now an opportunity to establish the precise relationship between exhaled nitric oxide, atopy and airway inflammation, and to investigate whether or not there is a role for the measurement of exhaled nitric oxide in the management of patients with asthma.

RECENT FINDINGS

A number of recent studies have investigated the relationship between exhaled nitric oxide and airway inflammation in asthma measured directly, using sputum induction, bronchoalveolar lavage and endobronchial biopsy. These measurements suggest that exhaled nitric oxide reflects eosinophilic airway inflammation in asthma, although there is no evidence for any relationship between exhaled nitric oxide and other airway inflammatory cells. Exhaled nitric oxide levels were found to be higher in atopic compared with nonatopic groups. These levels, however, are further elevated in atopic patients with asthma, suggesting that exhaled nitric oxide is not simply a marker of atopy. Although there is little evidence to support the routine use of measurement of exhaled nitric oxide in the management of patients with asthma, it may prove to be useful in assessing adherence to treatment with inhaled corticosteroids, or in the identification of patients in whom respiratory symptoms are associated with eosinophilic airway inflammation.

SUMMARY

There is good evidence that exhaled nitric oxide reflects eosinophilic airway inflammation in asthma. Well designed, long-term studies are needed to evaluate whether the addition of exhaled nitric oxide measurements to clinical and lung function assessment results in improved asthma control.

The relationship between exhaled nitric oxide and allergic sensitization in a random sample of school children

BACKGROUND

Exhaled nitric oxide (NO) has been proposed as novel a non-invasive marker of airway inflammation.

OBJECTIVE

The level of exhaled NO was determined in a random sample of school children (7-12 years old) with the aim of investigating the relationship between exhaled NO and sensitization to common allergens.

RESULTS

In the 450 children tested by skin prick tests (SPT), the prevalence of sensitization was 29.5% (overall), 21.9% (sensitization to indoor allergens), and 15.0% (sensitization to outdoor allergens). Regression analysis showed that levels of exhaled nitric oxide were closely associated with various measures of sensitization to aeroallergens. Sensitization to indoor allergens was associated with higher levels of exhaled NO (eNO) than sensitization to outdoor allergens when assessed by IgE but not when assessed by SPT. Children with reported wheeze in the past 12 months had much stronger associations between sensitization and eNO than children without wheeze.

CONCLUSION

We conclude that allergic sensitization is strongly associated with increased levels of exhaled NO, especially in children with wheeze.