Exhaled nitric oxide in the diagnosis and management of asthma: clinical implications

How Frequently Is Asthma Objectively Demonstrated before Starting a Biologic? Quality Assessment of a Group Practice of Allergists and Immunologists

Worldwide, asthma-related healthcare cost remains a major burden. Individuals with severe asthma account for 50% of that cost. Although they are expensive, biologics such as anti-IL5 and anti-IgE agents promise cost-effectiveness when judiciously used to decrease asthma-related hospitalization and the debilitating side effects of systemic corticosteroids. Before considering biologics to treat patients with asthma, current guidelines recommend confirmation of asthma and control of comorbid diseases. Diagnostic confirmation of asthma can be challenging among individuals with severe asthma. In this quality assessment study, we determined the frequency of objective asthma confirmation and addressing of comorbidities prior to starting biologics at a group practice of allergists and immunologists. We surveyed our specialty providers to understand habit(s) leading to the observed results. We identified 40 adult patients who started on biologic modifiers for asthma over the past 5 years. Only 58% of these patients had a proper diagnosis of asthma. Providers underutilized several diagnostic methods that may prove useful in confirming asthma diagnosis in this patient population. The factors contributing to poor asthma control were rarely addressed. A sense of urgency to initiate biologics was the primary reason for the observed results. Further interventions are needed to improve asthma diagnosis and management prior to the initiation of biologic therapeutics.

Exposure to Adverse Events and Associations with Stress Levels and the Practice of Yoga: Survey Findings from a Population-Based Study of Diverse Emerging Young Adults

Objectives: This study examines the prevalence of exposure to adverse events and associations with stress levels among a diverse population-based sample of young people. The study further explores whether these vulnerable populations, who have the potential to benefit from the mind-body practice of yoga, engage in a regular yoga practice. Design: EAT 2018 (Eating and Activity over Time) is a population-based study in which survey data were collected from 1568 ethnically/racially diverse (81.2% nonwhite) emerging young adults (mean age: 22.0 ± 2.0 years). Results: Exposure to adverse events was highly prevalent. For example, 43.9% reported at least one adverse childhood experience (ACE) (e.g., physical, emotional, or sexual abuse before age 18), whereas 40.1% reported experiencing discrimination. Exposure to adverse events was associated with higher stress levels. Practicing yoga at least 30 min/week was reported by 12.7% of the population, with variation across sociodemographic characteristics. Young adults exposed to adverse events were either more or similarly likely to practice yoga than young adults not reporting adverse events. Conclusions: The high prevalence of exposure to adverse events and associations with higher levels of stress points to a need for public health interventions. Thus, it was promising to find that young people exposed to adverse events, who may have greater emotional burdens, practice yoga at equal or greater proportions to those without these exposures. Given the potential benefits of yoga for populations living with high stress, it is important to develop further outreach efforts and provide accessible, acceptable, and affordable opportunities for practicing yoga.

FCER2 T2206C variant associated with FENO levels in asthmatic children using inhaled corticosteroids: The PACMAN study

BACKGROUND

The FCER2 gene, via encoding of the CD23 receptor, plays an important role in the regulation of IgE responses. A genetic variant of the FCER2 gene (T2206C) was previously shown to be associated with IgE levels in asthmatic children. IgE sensitization has also been linked to increased levels of fractional exhaled nitric oxide (FENO).

OBJECTIVE

To investigate whether the FCER2 T2206C variant influences FENO levels in asthmatic children with a reported use of inhaled corticosteroids (ICS).

METHODS

This cross-sectional study involved 593 asthmatic children with a reported use of ICS, availability of FENO measurements and genotyping data on the FCER2 T2206C variant (rs28364072). An additive genetic model was assumed, and the association between the FCER2 T2206C variant and the log-transformed (ln) FENO levels was evaluated using linear regression analysis, adjusted for age, sex, adapted British Thoracic Society (BTS) treatment steps and atopy.

RESULTS

The mean age of the population was 9.1 ± 2.2 years, and the median of FENO levels was 13.0 ppb with an interquartile range (IQR) of (8.0-27.5 ppb). The minor allele (G) frequency of rs28364072 was 29.6%, and each extra copy of the G allele was significantly associated with a lower level of the geometric mean of FENO (log scale, β = -0.12, 95% CI: -0.23, -0.02).

CONCLUSION AND CLINICAL RELEVANCE

Our results showed that the FCER2 T2206C variant was significantly associated with lower FENO levels in carriers of the G allele. Nevertheless, this SNP contributed little to the variability in FENO levels in this patient population. Our findings contribute to the present knowledge on FENO in asthmatic children; however, future replication studies are required to establish the role of this gene in relation to FENO.

Association between exhaled carbon monoxide and asthma outcomes in Peruvian children

BACKGROUND

Asthma prevalence continues to increase in low and middle-income countries, presenting challenges in assessing asthma control in resource-poor settings. Previous studies suggest that exhaled carbon monoxide (eCO) is higher with asthma severity and lower with treatment. We hypothesized that eCO levels may be elevated in children with asthma, particularly in children with partially controlled or uncontrolled asthma in a low-resource setting in Lima, Peru.

METHODS

We compared average eCO levels between 248 children with asthma and 221 healthy controls as well as the odds of asthma by eCO quartiles (0-1, 2, 3, and ≥4 ppm) using multivariable linear and logistic regression. eCO quartiles were also used to compare the odds of partially controlled or uncontrolled asthma (score ≤19 on the Asthma Control Test) in a multivariable logistic regression model.

FINDINGS

Average adjusted eCO level was 0.56 ppm (95% CI 0.07-1.05) higher in children with asthma. The adjusted odds of asthma were 1.22 (95% CI 0.75-1.97), 1.46 (0.81-2.63), and 1.76 (0.96-3.23) in the second, third, and fourth eCO quartiles compared to the first eCO quartile, respectively. Among children with asthma, the adjusted odds of partially controlled or uncontrolled asthma in those in the second, third, and fourth eCO quartiles, compared to the first, were 1.61 (95% CI 0.74-3.48), 3.66 (95% CI 1.51-8.87), and 2.50 (95% CI 1.06-5.90), respectively.

INTERPRETATION

eCO may serve as an inexpensive biomarker for asthma control, particularly in low-resource settings.

Family obligations and asthma in youth: The moderating role of socioeconomic status

OBJECTIVE

Fulfilling family obligations-providing instrumental help to and spending time with family-is a common aspect of family relationships. However, whether fulfilling these obligations links with physical health remains unclear. In this study, we investigated whether fulfilling family obligations was associated with asthma outcomes among youth, and whether these associations differed depending on family socioeconomic status (SES).

METHOD

Participants were 172 youth, 8 to 17 years of age (Mage = 12.1; 54% boys) who had been physician-diagnosed with asthma and reported on family-obligation frequency; completed the Asthma Control Test (ACT; Nathan et al., 2004), a clinical measure of asthma control; and completed a measure of airway inflammation (i.e., fractional exhaled nitric oxide). Parents also completed the ACT in reference to their asthmatic children and reported on family income.

RESULTS

Fulfilling family obligations was not associated with asthma outcomes (βs < .14, ps > .075). However, SES (family income) interacted with family obligations, such that fulfilling family obligations was associated with greater airway inflammation (interaction term β = -.17, p = .023) and poorer parent-reported asthma control (interaction term β = .15, p = .039), only among youth from lower SES backgrounds. Exploratory analyses suggest that these interactions were robust against covariates and were largely consistent across age and the two dimensions of family-obligation behaviors.

CONCLUSION

Findings from this study suggest that among youth from lower SES backgrounds, engaging in more frequent family-obligation behaviors may have negative repercussions in terms of their asthma. (PsycINFO Database Record

Recent advances in the diagnosis of allergic rhinitis

INTRODUCTION

Allergic rhinitis (AR) is a disorder with high prevalence worldwide. Identification of clinically relevant allergens is the key step for the diagnosis, allergen avoidance and allergen specific immunotherapy for AR. Areas covered: With the new findings of mechanisms of AR and the development of technology, much progress has been achieved in the diagnosis of AR recently. We review the recent advances about local IgE, in vivo and in vitro tests, cytological diagnosis and nitric oxide (NO) in the diagnosis of AR. Expert commentary: AR is traditionally diagnosed with the combined evaluation of history and allergen sensitization by in vivo skin prick tests and in vitro allergen specific IgE in serum, to confirm the correlation between clinical history and potential allergens. Nasal provocation test and local IgE measurement can be used to diagnose local AR. Allergen microarray has the ability to detect more potential allergens. Basophil activation and mast cell activation tests can be used in allergen diagnosis and to modify the response to immunotherapy, while cytological diagnosis is useful in the differential diagnosis of AR and non-AR. Nasal NO has been confirmed to be an optimal biomarker to discriminate between AR and non-AR.

Exhaled NO as a predictor of exercise-induced asthma in cold air

PURPOSE

Physical activity is an important part of life, and exercise-induced asthma (EIA) can reduce the quality of life. A standardized exercise challenge is needed to diagnose EIA, but this is a time consuming, effortful and expensive method. Exhaled nitric oxide (eNO) as a marker of eosinophil inflammation is determined rapidly and easily. The aim of this study was to investigate eNO as surrogate marker for predicting a positive reaction in an exercise challenge in a cold chamber (ECC).

METHODS

A total of 143 subjects aged 6-45 years with suspected EIA were recruited for the study. The subjects underwent an eNO measurement, an ECC and a skin prick test (SPT). To define the sensitivity and specificity of eNO as predictor, a receiver-operating characteristic (ROC) curve was plotted. The individual probability of the occurrence of a positive reaction after ECC based on an eNO value was calculated using a logistic regression model.

RESULTS

An eNO cut-off value of 18.5 ppb (area under the curve (AUC) 0.71, p < 0.001) showed the best combination of sensitivity and specificity for a positive reaction (forced expiratory volume in 1 s (FEV₁) decrease ≥ 10% after ECC) for the whole group. An eNO cut-off value of 46.0 ppb had a specificity of 100.0% to predict a significant FEV₁ decrease and may save exercise testing in 22.4% of patients. A negative predictive level with a high sensitivity and negative predictive value (NPV) could not be defined. In the subgroup that was house dust might (HDM) allergy positive (HDM pos; n = 68, 45.5% of all subjects), an eNO cut-off value of 35.5 ppb (AUC 0.79, p < 0.01) showed the best combination of sensitivity and specificity for a positive reaction after the ECC with a specificity 100.0% and may save exercise testing in 45.6% of HDM pos patients. Using logistic regression, a 95% probability for a positive FEV₁ decrease after ECC was estimated at 53 ppb for the whole group and at 47 ppb for the HDM pos subgroup.

CONCLUSIONS

Exhaled NO measurement is a screening tool for EIA, especially in HDM pos subjects. In a real-life setting, a cut-off value of 46.0 ppb detects EIA at 100% in all suspected patients, and a cut-off level of 35.5 ppb is valuable marker of EIA in patients with an HDM allergy. These levels can save time and costs in a large proportion of patients and will be helpful for clinicians.

FeNO and Exercise Testing in Children at Risk of Asthma

BACKGROUND

Exercise testing is the gold standard for diagnosing exercise-induced bronchoconstriction in children, but requires considerable cooperation and medical resources. Therefore, fraction of exhaled nitric oxide (FeNO) has been proposed as a tool to predict the need for exercise testing.

OBJECTIVE

The objective of this study was to investigate the relationship between FeNO, exercise test results, and a history of respiratory symptoms during exercise in children at risk of asthma.

METHODS

FeNO measurement, exercise testing, and interview about respiratory symptoms during exercise were completed in 224 seven-year-old children from the at-risk Copenhagen Prospective Studies on Asthma in Childhood₂₀₀₀ birth cohort. The associations between FeNO, exercise test results, and reported respiratory symptoms during exercise were analyzed adjusting for gender, respiratory infections, and inhaled corticosteroid treatment. The associations were also analyzed stratified by asthma and atopic status.

RESULTS

Of the 224 children, 28 (13%) had an established asthma diagnosis and 58 (26%) had a positive exercise test (≥15% drop in forced expiratory volume in 1 second [FEV₁] from baseline). FeNO and bronchial obstruction after exercise were linearly associated with a doubling of FeNO corresponding to a 2.4% drop in FEV₁ (95% confidence interval, 0.8-4.1; P < .01). However, a receiver operating characteristic curve analysis showed that the best cutoff of FeNO for predicting exercise test outcome among children who reported respiratory symptoms during exercise was 17 ppb, which only had 74% negative predictive value. There was no association between FeNO and reported respiratory symptoms during exercise (odds ratio = 1.3 [0.8-1.9]; P = .29) or reported symptoms during exercise and exercise test results (odds ratio = 1.0 [1.0-1.1]; P = .12).

CONCLUSIONS

A history of respiratory symptoms during exercise was not associated with either elevated FeNO or a positive exercise test in children at risk of asthma. FeNO and exercise test results were linearly associated traits, but FeNO could not reliably be used dichotomized to predict the need of exercise testing.

Role of Exhaled Nasal Nitric Oxide in Distinguishing between Chronic Rhinosinusitis with and without Nasal Polyps

Background

Chronic rhinosinusitis (CRS) with nasal polyps (CRSwNP) and CRS without nasal polyps (CRSsNP) nasal polyps is a global health concern. Several clinical biomarkers, such as inhaled carbon monoxide and exhaled nitric oxide (NO), have been studied to assess the presence and degree of inflammation in the airway mucosa.

Objective

To evaluate the clinical application of exhaled nasal NO (nNO) in distinguishing between CRSwNP and CRSsNP in consideration of the atopic status of patients.

Methods

Eighty-eight patients with CRS and 20 healthy volunteers were recruited for this study. The exhaled nNO level was measured by using a hand-held device. Nasal endoscopy (with Lund-Mackay scoring of CRS) and sinus computed tomographies (CT) were used to evaluate the nasal cavity and sinuses of the subjects. Atopic status was confirmed by using skin prick tests (SPTs).

Results

The mean ∓ standard deviation (SD) levels of nNO in patients with CRSsNP were significantly higher than those in patients with CRSwNP (591 ∓ 153 ppb versus 360 ∓ 181 ppb, p <0.001), whereas patients with CRS exhibited lower levels of nNO compared with the control subjects (449 ∓ 204 ppb versus 881 ∓ 161 ppb, p <0.001). Patients with atopy and with and without nasal polyps exhibited significantly higher levels of nNO compared with patients without atopy (atopic CRSsNP versus nonatopic CRSsNP, 734 ∓ 220 ppb versus 503 ∓ 92 ppb [p <0.001]; atopic CRSwNP versus nonatopic CRSwNP, 518 ∓ 161 ppb versus 299 ∓ 150 ppb [p <0.001]). The levels of nNO were negatively correlated with the Lund-Mackay scores in both atopic (r = -0.45; p = 0.016) and nonatopic (r = -0.600; p <0.001) patients with CRS. Receiver operating characteristic curves differentiated patients as CRSwNP, CRSsNP, and healthy controls, and in atopic and nonatopic subgroups, with acceptable sensitivity and specificity (>70 to 90%).

Conclusion

Exhaled nNO levels can be used to distinguish between patients with CRSwNP and patients with CRSsNP. However, the atopic status of the patient influenced the use of nNO as a diagnostic or monitoring biomarker in CRS.

Optimal flow rate sampling designs for studies with extended exhaled nitric oxide analysis

INTRODUCTION

The fractional concentration of exhaled nitric oxide (FeNO) is a biomarker of airway inflammation. Repeat FeNO maneuvers at multiple fixed exhalation flow rates (extended NO analysis) can be used to estimate parameters quantifying proximal and distal sources of NO in mathematical models of lower respiratory tract NO. A growing number of studies use extended NO analysis, but there is no official standard flow rate sampling protocol. In this paper, we provide information for study planning by deriving theoretically optimal flow rate sampling designs.

METHODS

First, we reviewed previously published designs. Then, under a nonlinear regression framework for estimating NO parameters in the steady-state two compartment model of NO, we identified unbiased optimal four flow rate designs (within the range of 10-400 ml s^-1) using theoretical derivations and simulation studies. Optimality criteria included NO parameter standard errors (SEs). A simulation study was used to estimate sample sizes required to detect associations with NO parameters estimated from studies with different designs.

RESULTS

Most designs (77%) were unbiased. NO parameter SEs were smaller for designs with: more target flows, more replicate maneuvers per target flow, and a larger range of target flows. High flows were most important for estimating alveolar NO concentration, while low flows were most important for the proximal NO parameters. The Southern California Children's Health Study design (30, 50, 100 and 300 ml s^-1) had ≥1.8 fold larger SEs and required 1.1-3.2 fold more subjects to detect the association of a determinant with each NO parameter as compared to an optimal design of 10, 50, 100 and 400 ml s^-1.

CONCLUSIONS

There is a class of reasonable flow rate sampling designs with good theoretical performance. In practice, designs should be selected to balance the tradeoffs between optimality and feasibility of the flow range and total number of maneuvers.

Exhaled nitric oxide in the diagnosis of asthma in adults: a systematic review

OBJECTIVES

To identify and synthesize evidence on the diagnostic accuracy of _FE NO for asthma in adults.

MATERIALS AND METHODS

Systematic searches (nine key biomedical databases and trial registers) were carried out on November 2014. Records were included if they recruited patients with the symptoms of asthma; used a single set of inclusion criteria; measured _FE NO₅₀ in accordance with American Thoracic Society guidelines, 2005 (off-line excluded); reported/allowed calculation of true-positive, true-negative, false-positive and false-negative patients as classified against any reference standard. Study quality was assessed using QUADAS II. Meta-analysis was planned where clinical study heterogeneity allowed. Rule-in and rule-out uses of _FE NO were considered.

RESULTS

A total of 4861 records were identified originally and 1312 in an update. Twenty-seven studies were included. Heterogeneity precluded meta-analysis. Results varied even within subgroups of studies. Cut-off values for the best sum of sensitivity and specificity varied from 12 to 55 p.p.b., but did not produce high accuracy. 100% sensitivity or 100% specificity was reported by some studies indicating potential use as a rule-in or rule-out strategy.

CONCLUSIONS AND CLINICAL RELEVANCE

_FE NO₅₀ had variable diagnostic accuracy even within subgroups of studies with similar characteristics. Diagnostic accuracy, optimal cut-off values and best position for _FE NO₅₀ within a pathway remain poorly evidenced.

Clinical Utility of Fractional exhaled Nitric Oxide (FeNO) as a Biomarker to Predict Severity of Disease and Response to Inhaled Corticosteroid (ICS) in Asthma Patients

INTRODUCTION

Bronchial asthma is a common chronic inflammatory airway disease diagnosed and is based on symptomatic history and Pulmonary Function Tests (PFT). Fractional exhaled Nitric Oxide (FeNO) is exclusively a non-invasive biomarker of on-going eosinophilic airway inflammation which remains unpredictable only with PFTs. FeNO measurement is recommended in predicting asthma severity and Inhaled Corticosteroid (ICS) response but further research is required to understand its clinical utility and agreement with current recommendations in a specific population.

AIM

To estimate FeNO levels in Tamilian patients with mild-to-moderate persistent asthma and to correlate with disease severity and ICS response.

MATERIALS AND METHODS

The study was a prospective cohort with a single group of 102 persistent asthma patients under standard ICS regimen for 8 weeks (follow-up period). PFT and FeNO were measured using portable spirometry and chemiluminescence based exhaled breath analyser, at baseline and during follow-up visits. Based on PFT and FeNO parameters, the study population was sub-grouped with respect to asthma severity (as mild, moderate and moderately severe), FeNO cut-off (> or < 50ppb) and ICS response classification (good vs poor ICS responders).

RESULTS

Significant decrease in mean FeNO levels were found in mild, moderate and moderately severe asthmatic groups following ICS treatment (90.15±27.36, 75.74±31.98 and 77.18±32.79 ppb) compared to similar baseline FeNO levels (103.03±34.08, 91.38±37.60 and 97.90±43.84 ppb) in all the above groups. Similarly, significant decrease in mean FeNO levels was found - FeNO>50ppb, good and poor ICS responders groups, in post- ICS treatment (89.63±24.04, 77.90±31.12 and 86.49±32.57 ppb) compared to baseline levels (110.183±1.23, 97.12±42.04 and 99.68±34.71 ppb).

CONCLUSION

The observed baseline FeNO values in all groups as stated above did not show significant difference to differentiate asthma severity or ICS responders groups. The present study results do not support the predictive association of baseline FeNO levels with asthma severity and future ICS response, but the decrements in FeNO levels on ICS treatment, supports its clinical utility in monitoring of ongoing airway inflammation and understanding treatment response rate.

Can exhaled nitric oxide be a surrogate marker of bronchial hyperresponsiveness to adenosine 5'-monophosphate in steroid-naive asthmatic children?

BACKGROUND

The interrelation between airway inflammation, bronchial hyperresponsiveness (BHR) and atopy remains controversial.

OBJECTIVE

The aim of this study was to document whether exhaled nitric oxide (eNO) may be used as a surrogate marker that predicts BHR to adenosine 5'-monophosphate (AMP) in steroid-naive school children with asthma.

METHODS

This study was a retrospective analysis of steroid-naive school age children with atopic and non-atopic asthma. All patients whose eNO levels had been measured and who had been challenged with both methacholine (MCH) and AMP were included. Receiver operation characteristic analysis was performed, in both the atopic and the non-atopic groups, to evaluate the ability of eNO to detect the BHR to AMP.

RESULTS

One hundred and sixteen patients, sixty-nine (59.5%) of whom had been atopic, were included in the analysis. In the atopic group, eNO values were significantly higher in patients with BHR to AMP compared to those without BHR to AMP (51.9 ± 16.9 p.p.b. vs. 33.7 ± 16.4 p.p.b.; P < 0.001), whereas in the non-atopic group, the differences were not statistically significant (29.7 ± 16.9 p.p.b. vs. 22.6 ± 8.1 p.p.b.; P = 0.152). In the atopic group, eNO levels (R(2) : 0.401; β: 0.092; 95% CI: 1.19-14.42; OR: 7.12; P = 0.008) were found to be the only independent factor for BHR to AMP, whereas none of the parameters predicted BHR to AMP in the non-atopic group. The best cut-off value of eNO that significantly predicts BHR to AMP was 33.3 p.p.b. in the atopic group (P < 0.001), whereas a significant cut-off value for eNO that predicts BHR to AMP was not determined in the non-atopic group (P = 0.142). An eNO ≤ 17.4 p.p.b. has 100% negative predictive values and 100% sensitivity and 60.47% PPV for prediction of BHR to AMP in the atopic group.

CONCLUSIONS

Exhaled NO may be used to predict BHR to AMP in atopic but not in non-atopic steroid-naïve asthmatic children.

A pathophysiological approach for FeNO: A biomarker for asthma

The present review is focused on literature concerning the relevance of fractional exhaled nitric oxide (FeNO) in clinical practice from a pathophysiological point of view. There is increasing evidence that asthma is a heterogeneous pathological condition characterised by different phenotypes/endotypes related to specific biomarkers, including FeNO, helpful to predict therapeutic response in selected asthmatic populations. Nowadays FeNO, a non-invasive biomarker, appears to be useful to foresee asthma developing, to recognise specific asthma phenotypes, like the eosinophilic, to ameliorate asthma diagnosis and management in selected populations and to predict standard corticosteroid and biologic therapy efficacy. In addition, FeNO assessment may also be useful in patients with allergic rhinitis in order to detect the potential involvement of eosinophilic bronchial inflammation in "case finding" subjects at risk of asthma diagnosis. Therefore, it is possible to hypothesise a future with an appropriate use of FeNO by physicians dealing with worrisome clinical issues in specific asthma phenotypes.

Oxidative stress and volatile organic compounds: interplay in pulmonary, cardio-vascular, digestive tract systems and cancer

Oxidative stress (OS) can be defined as an imbalance between antioxidant systems and various pro-oxidants. This loss of balance is closely associated with initiation and development of a wide range of systemic or organ specific diseases.

Exhaled breath of healthy humans contains a large number of volatile organic compounds (VOCs) derived from cellular metabolism, released by microorganisms or taken up from the environment. Qualitative or quantitative changes in their composition are associated with diseases and various pathological conditions, also characterized by increased production of reactive oxygen species (ROS), such as superoxide radical, hydrogen peroxide, hydroxyl anion, peroxinitrite, etc. Several volatile organic compounds such as ethane and pentane are direct end-products of the reaction of ROS with various biological compounds (e.g., lipid peroxidation, DNA or protein damage). Being able to accurately identify ROS-generated VOCs could be of particular importance in devising sensitive tests that can diagnose and follow-up oxidative stress-related diseases.

This review describes current knowledge on the associations between oxidative stress and free radicals and the release of several marker volatile organic compounds in a number of diseases. A special focus will be placed on such VOCs in the cardiovascular pathologies, pulmonary diseases and gastro-intestinal tract affections.

Estimation of parameters in the two-compartment model for exhaled nitric oxide

The fractional concentration of exhaled nitric oxide (FeNO) is a biomarker of airway inflammation that is being increasingly considered in clinical, occupational, and epidemiological applications ranging from asthma management to the detection of air pollution health effects. FeNO depends strongly on exhalation flow rate. This dependency has allowed for the development of mathematical models whose parameters quantify airway and alveolar compartment contributions to FeNO. Numerous methods have been proposed to estimate these parameters using FeNO measured at multiple flow rates. These methods—which allow for non-invasive assessment of localized airway inflammation—have the potential to provide important insights on inflammatory mechanisms. However, different estimation methods produce different results and a serious barrier to progress in this field is the lack of a single recommended method. With the goal of resolving this methodological problem, we have developed a unifying framework in which to present a comprehensive set of existing and novel statistical methods for estimating parameters in the simple two-compartment model. We compared statistical properties of the estimators in simulation studies and investigated model fit and parameter estimate sensitivity across methods using data from 1507 schoolchildren from the Southern California Children's Health Study, one of the largest multiple flow FeNO studies to date. We recommend a novel nonlinear least squares model with natural log transformation on both sides that produced estimators with good properties, satisfied model assumptions, and fit the Children's Health Study data well.

Increased exhaled nitric oxide levels after exercise in patients with chronic systolic heart failure with pulmonary venous hypertension

BACKGROUND

Fractional exhaled nitric oxide (eNO) is recognized as a marker of pulmonary endothelial function. Oxidative stress is associated with systemic endothelial nitric oxide production, but its correlation with eNO in heart failure (HF) patients has not been described. Previous studies have reported increased eNO levels after exercise in symptomatic HF patients but decreased levels with pulmonary arterial hypertension. Our objective was to prospectively examine the potential myocardial and functional determinants of exercise-induced rise of eNO in HF.

METHODS AND RESULTS

Thirty-four consecutive ambulatory patients with chronic systolic HF (left ventricular ejection fraction [LVEF] ≤45%) underwent symptom-limited cardiopulmonary stress testing and echocardiography. eNO was determined immediately after exercise. Systemic endothelial dysfunction was assessed by asymmetric dimethylarginine (ADMA) and the L-arginine/ADMA ratio. In our study cohort (mean age 53 ± 13 years, 76% male, median LVEF 31%, interquartile range [IQR] 25%-40%), the mean eNO was 23 ± 9 ppb. eNO levels were higher in patients with diastolic dysfunction stages 2 or 3 than stage 1 or normal diastology (26.1 ± 9 vs 19.5 ± 7 ppb; P = .013). eNO had a positive correlation with estimated systolic pulmonary artery pressure (r = 0.57; P = .0009) and indexed left atrium volume (r = 0.43; P = .014), but it did not correlate with cardiopulmonary exercise test parameters, ADMA, or symptom score.

CONCLUSIONS

In contrast to earlier reports, the increase in postexercise eNO observed in stable chronic systolic HF patients may be attributed to the presence of underlying pulmonary venous hypertension probably secondary to advanced diastolic dysfunction.

Web-based family intervention for overweight children: a pilot study

BACKGROUND

Research has shown the efficacy of family-based behavioral interventions for overweight children, but a major difficulty is access to effective treatment programs. The objective of this study was to develop and test the initial feasibility and efficacy of a web-based family program for overweight 8- to 12-year-old children.

METHODS

A website was created using concepts from effective family-based behavioral programs and input from focus groups with overweight children, parents, and pediatricians. The website provided information about obesity and healthy lifestyles, assessment of dietary and physical activity habits, interactive dietary and physical activity games, and instruction in goal-setting and monitoring of goals. Children selected a dietary and physical activity goal and a daily step goal with pedometers. Feasibility and pilot testing over 4 weeks was conducted with 24 overweight children referred by a physician. Outcomes were z-BMI, healthy eating and physical activity, and intrinsic motivation and self-efficacy for weight control.

RESULTS

Mean number of logins over the study period was 11.4 for the study sample. Eighteen families (75%) returned for the follow-up assessment. Pre-post analyses for these participants showed improvements in intrinsic motivation, (p=0.05), self-efficacy (p=0.025), physical activity (p=0.005), and healthy lifestyle behaviors (p=0.001). Comparisons between high and low users of the program indicated that high users reduced their BMI while low users increased their BMI over time (p=0.02); high users also improved their dietary intake relative to low users (p=0.04). Consumer satisfaction ratings were high.

CONCLUSION

These pilot findings suggest this is a feasible approach for treatment of overweight children and that children who used the web program frequently improved their BMI and dietary intake.

High exhaled nitric oxide levels may predict bronchial reversibility in allergic children with asthma or rhinitis

BACKGROUND

Allergic asthma and rhinitis may be associated. Airway inflammation is shared by both disorders. The measure of the fractional concentration of exhaled nitric oxide (FeNO) may be considered as a surrogate marker for airway inflammation, mainly in allergic patients. Reversibility to bronchodilation (BD) testing is a functional characteristic of asthma.

OBJECTIVE

The aim of this study was to evaluate whether FeNO may predict reversibility to BD in a pediatric cohort of allergic subjects with asthma (180) or rhinitis (150).

METHODS

Lung function (including forced expiratory volume at the first second (FEV(1)), forced volume capacity (FVC), forced expiratory flow at 25-75% of volume capacity (FEF (25-75))), FeNO measurement, and BD testing were performed in all children.

RESULTS

Lung function, FeNO, and sensitization type were significantly different in the two groups. A strong correlation was found between FeNO and ΔFEV(1) after BD. Two main predictors of reversibility were FeNO values >34 ppb [Odds RatioAdj (ORAdj) = 1.9] and sensitization to perennial allergens (ORAdj = 1.7).

CONCLUSIONS

This study provided evidence that FeNO was strongly related with the response to BD testing and could predict bronchial reversibility in children with allergic rhinitis or asthma. Therefore, a simple FeNO measurement could suggest relevant information about bronchial reversibility.

Nitric oxide and superoxide mediate diesel particle effects in cytokine-treated mice and murine lung epithelial cells--implications for susceptibility to traffic-related air pollution

Background

Epidemiologic studies associate childhood exposure to traffic-related air pollution with increased respiratory infections and asthmatic and allergic symptoms. The strongest associations between traffic exposure and negative health impacts are observed in individuals with respiratory inflammation. We hypothesized that interactions between nitric oxide (NO), increased during lung inflammatory responses, and reactive oxygen species (ROS), increased as a consequence of traffic exposure ─ played a key role in the increased susceptibility of these at-risk populations to traffic emissions.

Methods

Diesel exhaust particles (DEP) were used as surrogates for traffic particles. Murine lung epithelial (LA-4) cells and BALB/c mice were treated with a cytokine mixture (cytomix: TNFα, IL-1β, and IFNγ) to induce a generic inflammatory state. Cells were exposed to saline or DEP (25 μg/cm²) and examined for differential effects on redox balance and cytotoxicity. Likewise, mice undergoing nose-only inhalation exposure to air or DEP (2 mg/m³ × 4 h/d × 2 d) were assessed for differential effects on lung inflammation, injury, antioxidant levels, and phagocyte ROS production.

Results

Cytomix treatment significantly increased LA-4 cell NO production though iNOS activation. Cytomix +  DEP-exposed cells incurred the greatest intracellular ROS production, with commensurate cytotoxicity, as these cells were unable to maintain redox balance. By contrast, saline + DEP-exposed cells were able to mount effective antioxidant responses. DEP effects were mediated by: (1) increased ROS including superoxide anion (O₂˙^-), related to increased xanthine dehydrogenase expression and reduced cytosolic superoxide dismutase activity; and (2) increased peroxynitrite generation related to interaction of O₂˙^- with cytokine-induced NO. Effects were partially reduced by superoxide dismutase (SOD) supplementation or by blocking iNOS induction. In mice, cytomix +  DEP-exposure resulted in greater ROS production in lung phagocytes. Phagocyte and epithelial effects were, by and large, prevented by treatment with FeTMPyP, which accelerates peroxynitrite catalysis.

Conclusions

During inflammation, due to interactions of NO and O₂˙^-, DEP-exposure was associated with nitrosative stress in surface epithelial cells and resident lung phagocytes. As these cell types work in concert to provide protection against inhaled pathogens and allergens, dysfunction would predispose to development of respiratory infection and allergy. Results provide a mechanism by which individuals with pre-existing respiratory inflammation are at increased risk for exposure to traffic-dominated urban air pollution.

Exhaled nitric oxide may predict bronchial hyperreactivity in patients with allergic rhinitis

BACKGROUND

Nowadays it is possible to assess airway inflammation by measuring the fractional concentration of exhaled nitric oxide (FeNO) during an office visit and there is international consensus on the testing methodology. The aim of this study was to evaluate whether FeNO measurement may be a predictor of bronchial hyperreactivity (BHR) in patients with allergic rhinitis (AR).

METHODS

Two hundred eleven patients (196 males, median age 28.5 years) suffering from persistent AR were evaluated. Values for bronchial function (FVC, FEV(1), and FEF(25-75)), bronchial provocation tests (methacholine), exhaled nitric oxide (FeNO), a visual analogue scale for nasal and bronchial symptoms, and sensitization were assessed.

RESULTS

A strong and inverse correlation between FeNO levels and BHR severity was found (r = -0.58). FeNO was a predictive factor for BHR, and 37 ppb was found to be the best cutoff (area under the curve 0.90) to define the presence of BHR in patients with AR.

CONCLUSIONS

This study highlights the relevance of FeNO as a possible predictive marker for BHR in AR patients and underlines the close link between upper and lower airways. Thus, FeNO measurement could be a useful screening tool in identifying subjects with rhinitis at risk of developing asthma.

Exhaled NO is a poor marker of asthma control in children with a reported use of asthma medication: a pharmacy-based study

BACKGROUND

A high fraction of nitric oxide in exhaled breath (FeNO) has been suggested to be a marker of ongoing airway inflammation and poorly controlled disease in asthma. The usefulness of FeNO to monitor asthma control is still debated today.

AIM

To assess the validity of FeNO as a marker of asthma control in children with reported use of asthma medication.

METHODS

Fraction of nitric oxide in exhaled breath was measured in 601 children (aged 4-12 yr) with reported use of asthma medication in the past 6 months and in 63 healthy non-asthmatic children (aged 5-12). Asthma control was assessed by the Asthma Control Questionnaire (ACQ). A receiver-operator characteristics (ROC) curve was generated to assess the accuracy of FeNO as a marker for asthma control. Logistic regression analysis was used to study whether clinical, healthcare, medication, and environmental factors are associated with high FeNO levels (>25 ppb).

RESULTS

Fraction of nitric oxide in exhaled breath had a poor accuracy to discriminate well-controlled from not well-controlled asthma [area under the ROC curve: 0.56 (95% CI: 0.52-0.61, p = 0.008)]. In addition, high FeNO (>25 ppb) was associated with lower medication adherence rates (OR: 0.4; 95% CI 0.3-0.6), fewer antibiotic courses in the past year (OR: 0.6; 95% CI: 0.4-0.9), fewer leukotriene antagonists use in the past year (OR: 0.4; 95% CI: 0.2-0.9), and fewer visits to a (pulmonary) pediatrician (OR: 0.6; 95% CI: 0.4-0.9). Children living in a non-urban environment had more often high FeNO levels (OR: 1.7; 95% CI: 1.1-2.6).

CONCLUSION

High FeNO is a poor marker of asthma control in children with reported use of asthma medication. Various other factors, including medication adherence and medication use, are associated with increased FeNO levels.

Healthier food choices as a result of the revised healthy diet programme Krachtvoer for students of prevocational schools

BACKGROUND

Krachtvoer is a Dutch healthy diet programme for prevocational schools, developed in 2001 and revised for a broader target group in 2007, based on the findings of an evaluation of the first version. The goal of this study was to report on the short- and longer-term total and subgroup effects of the revised programme on students' fruit, fruit juice, breakfast, and snack consumption.

METHODS

Schools were randomized to the experimental condition, teaching the Krachtvoer programme, or to the control condition teaching the regular nutrition lessons. Self-reported consumption of fruit, fruit juice, breakfast and snacks was measured at baseline directly before programme implementation, one to four weeks after finishing programme implementation, and after six months. Mixed linear and logistic regression analyses were conducted.

RESULTS

In total 1117 students of 13 experimental schools and 758 students of 11 control schools participated in the study. Short- and longer-term favourable intervention effects were found on fruit consumption (mean difference between experimental and control group 0.15 servings at both posttests). Regarding fruit juice consumption, only short-term favourable effects were revealed (mean difference between experimental and control group 0.05 glasses). Intervention effects on breakfast intakes were limited. No changes in snack frequency were reported, but students made healthier snack choices as a result of the programme. Some favourable as well as unfavourable effects occurred in subgroups of students.

CONCLUSIONS

The effects on fruit consumption and snack choices justify the current nationwide dissemination of the programme. Achieving changes in breakfast consumption may, however, require other strategies.

High-intensity training improves airway responsiveness in inactive nonasthmatic children: evidence from a randomized controlled trial

PURPOSE

the relationship between physical activity and airway health in children is not well understood. The purpose of this study was to determine whether 8 wk of high-intensity exercise training would improve airway responsiveness in prepubescent, nonasthmatic, inactive children.

METHODS

16 healthy, prepubescent children were randomized [training group (TrG) n = 8, control group (ConG) n = 8]. Prior to and following 8 wk of training (or no training), children completed pulmonary function tests (PFTs): forced expiratory volume in 1 s (FEV(1)), forced vital capacity (FVC), forced expiratory flow at 25-75% of vital capacity (FEF(25-75)), and exhaled nitric oxide (FENO). Children completed an incremental cycle Vo(2max) test, eucapnic voluntary hyperventilation (EVH), anthropometric tests, and blood tests to determine fasting blood glucose, total cholesterol, HDL, LDL, and triglycerides. Body fat percentage was determined using dual-energy X-ray absorptiometry pretraining and bioelectrical impedance pre- and posttraining.

RESULTS

there were no differences (P > 0.05) in anthropometric measures or PFTs between TrG and ConG at baseline. In the TrG, there was a significant increase in Vo(2max) (∼24%) and a decrease in total cholesterol (∼13%) and LDL cholesterol (∼35%) following training. There were improvements (P < 0.05) in ΔFEV(1) both postexercise (pre: -7.60 ± 2.10%, post: -1.10 ± 1.80%) and post-EVH (pre: -6.71 ± 2.21%, post: -1.41 ± 1.58%) with training. The ΔFEF(25-75) pre-post exercise also improved with training (pre: -16.10 ± 2.10%, post: -6.80 ± 1.80%; P < 0.05). Lower baseline body fat percentages were associated with greater improvements in pre-post exercise ΔFEV(1) following training (r = -0.80, P < 0.05).

CONCLUSION

these results suggest that in nonasthmatic prepubescent children, inactivity negatively impacts airway responsiveness, which can be improved with high-intensity training. Excess adiposity, however, may constrain these improvements.

The Peru Urban versus Rural Asthma (PURA) Study: methods and baseline quality control data from a cross-sectional investigation into the prevalence, severity, genetics, immunology and environmental factors affecting asthma in adolescence in Peru

OBJECTIVES

According to a large-scale international survey, Peru has one of the highest prevalences of asthma worldwide; however, data from this survey were limited to participants from urban Lima. The authors sought to characterise the epidemiology of asthma in Peru in two regions with disparate degrees of urbanisation. In this manuscript, the authors summarise the study design and implementation.

DESIGN

A cross-sectional study.

PARTICIPANTS

Using census data of 13-15-year-old adolescents from two communities in Peru, the authors invited a random sample of participants in Lima (n=725) and all adolescents in Tumbes (n=716) to participate in our study.

PRIMARY AND SECONDARY OUTCOME MEASURES

The authors asked participants to complete a questionnaire on asthma symptoms, environmental exposures and socio-demographics and to undergo spirometry before and after bronchodilator, skin allergy testing and exhaled nitric oxide testing. The authors obtained blood samples for haematocrit, total IgE levels, vitamin D levels and DNA in all participants and measured indoor particulate matter concentrations for 48 h in a random subset of 70-100 households at each site.

RESULTS

Of 1851 eligible participants, 1441 (78%) were enrolled and 1159 (80% of enrolled) completed all physical tests. 1283 (89%) performed spirometry according to standard guidelines, of which 86% of prebronchodilator tests and 92% of postbronchodilator tests were acceptable and reproducible. 92% of allergy skin tests had an adequate negative control. The authors collected blood from 1146 participants (79%) and saliva samples from 148 participants (9%). Overall amounts of DNA obtained from blood or saliva were 25.8 μg, with a 260/280 ratio of 1.86.

CONCLUSIONS

This study will contribute to the characterisation of a variety of risk factors for asthma, including urbanisation, total IgE levels, vitamin D levels and candidate genes, in a resource-poor setting. The authors present data to support high quality of survey, allergic, spirometric and genetic data collected in our study.

Prevalence of asthma symptoms based on the European Community Respiratory Health Survey questionnaire and FENO in university students: gender differences in symptoms and FENO

BACKGROUND

The fractional concentration of nitric oxide in exhaled air (FENO) is used as a biomarker of eosinophilic airway inflammation. FENO is increased in patients with asthma. The relationship between subjective asthma symptoms and airway inflammation is an important issue. We expected that the subjective asthma symptoms in women might be different from those in men. Therefore, we investigated the gender differences of asthma symptoms and FENO in a survey of asthma prevalence in university students.

METHODS

The information about asthma symptoms was obtained from answers to the European Community Respiratory Health Survey (ECRHS) questionnaire, and FENO was measured by an offline method in 640 students who were informed of this study and consented to participate.

RESULTS

The prevalence of asthma symptoms on the basis of data obtained from 584 students (266 men and 318 women), ranging in age from 18 to 24 years, was analyzed. Wheeze, chest tightness, an attack of shortness of breath, or an attack of cough within the last year was observed in 13.2% of 584 students. When 38.0 ppb was used as the cut-off value of FENO to make the diagnosis of asthma, the sensitivity was 86.8% and the specificity was 74.0%. FENO was ≥ 38.0 ppb in 32.7% of students. FENO was higher in men than in women. The prevalence of asthma symptoms estimated by considering FENO was 7.2%; the prevalence was greater in men (9.4%) than women (5.3%). A FENO ≥ 38.0 ppb was common in students who reported wheeze, but not in students, especially women, who reported cough attacks.

CONCLUSIONS

The prevalence of asthma symptoms in university students age 18 to 24 years in Japan was estimated to be 7.2% on the basis of FENO levels as well as subjective symptoms. Gender differences were observed in both FENO levels and asthma symptoms reflecting the presence of eosinophilic airway inflammation.

TRIAL REGISTRATION NUMBER

UMIN000003244.

Monitoring asthma status

PURPOSE

Asthma is a chronic disorder of the airways involving inflammation and airway hyper-reactivity. Clinical diagnosis and monitoring of asthma must incorporate the immunological, biochemical, and histological changes of a chronic disorder, while recognizing acute phenotypic changes in order to optimally tailor therapeutics to each individual.

RECENT FINDINGS

Articles published within the previous 18 months are summarized in this article in order to present an up to date review of the latest findings regarding the monitoring of asthma. The articles encompass a wide array of specialties from basic research and histology to clinical medicine as well as community medicine and nursing.

SUMMARY

Exciting new advancements in the monitoring of asthma continue to unfold. Potentially new diagnostic and monitoring tools are highlighted in this study. Continued investigations may enable a select few methodologies to reach clinical utility in the ongoing monitoring and treatment of patients with asthma.

Modifiable lifestyle factors impact airway health in non-asthmatic prepubescent boys but not girls

INTRODUCTION

The prevalence of both childhood obesity and childhood asthma has increased dramatically over the past few decades. Little is known concerning the role of body composition and lifestyle influences on airway health in children.

PURPOSE

To determine whether body composition, fruit and vegetable intake (FV) and physical activity (PA) impact airway health in healthy prepubescent children.

METHODS

Pulmonary function tests (forced expiratory flow in 1-sec, forced vital capacity, forced expiratory flow at 25-75% of vital capacity) and exhaled nitric oxide (eNO) were measured pre- and post-exercise in 40 healthy (20 boys, 20 girls), non-asthmatic prepubescent children (age 9.7 ± 0.8 years). PA and FV intake were assessed via questionnaire. Each participant completed an incremental cycle-ergometer exercise test to exhaustion (V02 max). Body composition was measured via Dual Energy X-ray Absorptiometry. Participants were stratified by sex for analyses, and follow-up analyses were performed using a clinically significant drop in FEV1 of ≥ 10% to divide participants into groups.

RESULTS

In the overall group, the change in FEV1 (pre- and post-exercise) was inversely related (r = -0.47, P < 0.05) to % body fat; participants with the highest body fat demonstrated the greatest decrease in FEV1 (i.e., airway narrowing). When participants were divided by sex, this association held true only for boys (r = -0.61, P < 0.01). Percent body fat was the only significant contributor to the overall prediction of ΔFEV1 in boys. Boys engaged in significantly more PA than girls (3.45 ± 2.39; 2.00 ± 1.30 activities/day). Boys also had significantly higher V02 max adjusted for lean body mass than girls (48.06 ± 5.09; 42.30 ± 6.06). Body fat percent was not different by sex (P > 0.05). The participants in the ≥ 10% FEV1 group had a significantly greater body fat (28.1 ± 9.6%) compared to the <10% drop group (18.8 ± 9.8%).

CONCLUSION

These results suggest that PA, FV consumption, and body fat collectively impact airway health in prepubescent boys but not girls. Body fat, however, is the only independent predictor of post-exercise airway narrowing.

Gene expression patterns of Th2 inflammation and intercellular communication in asthmatic airways

Asthma is canonically thought of as a disorder of excessive Th2-driven inflammation in the airway, although recent studies have described heterogeneity with respect to asthma pathophysiology. We have previously described distinct phenotypes of asthma based on the presence or absence of a three-gene "Th2 signature" in bronchial epithelium, which differ in terms of eosinophilic inflammation, mucin composition, subepithelial fibrosis, and corticosteroid responsiveness. In the present analysis, we sought to describe Th2 inflammation in human asthmatic airways quantitatively with respect to known mediators of inflammation and intercellular communication. Using whole-genome microarray and quantitative real-time PCR analysis of endobronchial biopsies from 27 mild-to-moderate asthmatics and 13 healthy controls with associated clinical and demographic data, we found that asthmatic Th2 inflammation is expressed over a variable continuum, correlating significantly with local and systemic measures of allergy and eosinophilia. We evaluated a composite metric describing 79 coexpressed genes associated with Th2 inflammation against the biological space comprising cytokines, chemokines, and growth factors, identifying distinctive patterns of inflammatory mediators as well as Wnt, TGF-β, and platelet-derived growth factor family members. This integrated description of the factors regulating inflammation, cell migration, and tissue remodeling in asthmatic airways has important consequences for the pathophysiological and clinical impacts of emerging asthma therapeutics targeting Th2 inflammation.

Is there a relationship between asthma and dental caries?: a critical review of the literature

BACKGROUND

The authors conducted a critical review of the literature to ascertain the strength of the scientific and professional evidence supporting an association between dental caries and the experience and severity of asthma.

TYPES OF STUDIES REVIEWED

In March 2010, the authors searched Medline (1976-2010) by using the Ovid Web Gateway for the terms "asthma" and ["dental caries" or "dental caries susceptibility"] appearing in studies of humans published in English. The authors eliminated conference proceedings and abstracts, opinion pieces and unpublished studies; they included case series, cross-sectional, case-control and cohort studies and clinical trials.

RESULTS

The review yielded 27 studies described in 29 articles. The authors found that researchers have investigated the hypothesized relationship between asthma and caries by means of diverse strategies, often using asthma cases clustered in pools of patients seeking clinical care. The strongest methodological designs were more likely to reveal little support for a positive association. The authors found no strong evidence suggesting that a causal link exists. Future research incorporating better-defined covariates and longitudinal designs is needed.

CLINICAL IMPLICATIONS

Asthma per se may not be a risk factor for caries. Patients who have extreme dryness of the mouth, whose use of nebulizers is persistent, whose consumption of carbohydrates is frequent, and who have used multiple medications or have used medications over the long term necessitate cautious dental health care.

Exhaled nitric oxide in children with allergic rhinitis and/or asthma: a relationship with bronchial hyperreactivity

BACKGROUND

Nowadays, the measure of the fractional concentration of exhaled nitric oxide (FeNO) enables to assess airway inflammation during an office visit and there is international consensus on this testing methodology. The aim of this study was to evaluate whether FeNO measurement is predictable for bronchial hyperreactivity (BHR) in children with allergic rhinitis, asthma, or both.

METHODS

Two hundred and eighty children with allergic rhinitis, allergic asthma, or both were evaluated. Bronchial function (FEV₁ and FEF(25-75)), BHR (assessed by methacholine challenge), FeNO, and sensitizations were assessed.

RESULTS

Bronchial function, BHR, and FeNO were significantly different in the three groups (p < .001). A strong inverse correlation between FeNO and BHR was found in patients with asthma and with asthma and rhinitis (r = -0.63 and r = -0.61, respectively). A cutoff of 32 ppb of FeNO was a predictive factor for BHR.

CONCLUSIONS

This study highlights the relevance of FeNO as possible marker for BHR in allergic children and underlines the close link between upper and lower airways.

A patient with bronchial asthma in whom eosinophilic bronchitis and bronchiolitis developed during treatment

A 56-year-old woman was referred to our hospital because of dyspnea, wheezing, and a productive cough. Eight years before presentation, bronchial asthma was diagnosed and the patient received inhaled corticosteroids plus antiasthmatic agents (a long-acting inhaled beta2-agonist, leukotriene modifiers, and theophylline). Chest radiography showed small diffuse nodular shadows, and a computed tomographic scan showed thickening of the bronchi and bronchioles, with diffuse centrilobular nodules in both lung fields. A blood test and microscopic examination of the bronchoalveolar fluid revealed marked eosinophilia. Transbronchial lung biopsy and transbronchial biopsy showed eosinophilic bronchitis and bronchiolitis. After treatment with oral prednisolone (40 mg daily) and inhaled corticosteroids, the symptoms, blood eosinophilia, and radiographic findings improved. Recently, several similar cases of eosinophilic bronchiolitis have been reported. Studies of further cases and elucidation of the pathophysiology of eosinophilic bronchiolitis are necessary to establish a concept for this disease and to determine whether it should be classified as a subtype of bronchial asthma or as a distinct entity.

Effects of a high-fat meal on pulmonary function in healthy subjects

Obesity has important health consequences, including elevating risk for heart disease, diabetes, and cancer. A high-fat diet is known to contribute to obesity. Little is known regarding the effect of a high-fat diet on pulmonary function, despite the dramatic increase in the prevalence of respiratory ailments (e.g., asthma). The purpose of our study was to determine whether a high-fat meal (HFM) would increase airway inflammation and decrease pulmonary function in healthy subjects. Pulmonary function tests (PFT) (forced expiratory volume in 1-s, forced vital capacity, forced expiratory flow at 25-75% of vital capacity) and exhaled nitric oxide (eNO; airway inflammation) were performed in 20 healthy (10 men, 10 women), inactive subjects (age 21.9 +/- 0.4 years) pre and 2 h post HFM (1 g fat/1 kg body weight; 74.2 +/- 4.1 g fat). Total cholesterol, triglycerides, and C-reactive protein (CRP; systemic inflammation) were determined via a venous blood sample pre and post HFM. Body composition was measured via dual energy X-ray absorptiometry. The HFM significantly increased total cholesterol by 4 +/- 1%, and triglycerides by 93 +/- 3%. ENO also increased (p < 0.05) due to the HFM by 19 +/- 1% (pre 17.2 +/- 1.6; post 20.6 +/- 1.7 ppb). ENO and triglycerides were significantly related at baseline and post-HFM (r = 0.82, 0.72 respectively). Despite the increased eNO, PFT or CRP did not change (p > 0.05) with the HFM. These results demonstrate that a HFM, which leads to significant increases in total cholesterol, and especially triglycerides, increases exhaled NO. This suggests that a high-fat diet may contribute to chronic inflammatory diseases of the airway and lung.

[Feasibility of FeNO measurement in asthmatic children in the primary care setting. CANON Study]

AIM

Asses the feasibility of exhaled nitric oxide (FeNO) measurement in asthmatic children using a hand-held device in the primary care setting.

METHODS

Multicentre study performed in the paediatric clinics in seven Spanish primary health care centres. Each centre consecutively included 6-14 year-old children with doctor-diagnosed asthma. Children were asked to obtain two valid measurements of FeNO with the hand-held device NIOX MINO (Aerocrine AB, Solna, Sweden). Feasibility analysis included: (a) percentage of children able to perform the manoeuvre, (b) time required to obtain a successful determination, (c) number of attempts needed, and (d) acceptability of the technical procedure by clinical personnel involved in their guidance.

RESULTS

The Study enrolled 151 children. A total of 149 (98.7%) were able to perform the FeNO manoeuvre. The majority (55%) of children had previous experience of using the hand-held device. The Overall median (and Interquartile Range, IQR) of attempts needed to reach a first valid measurement was 2 (1-3) and median (IQR) of time taken was 4 min (3-5). Nurses considered the overall procedure was very easy or easy in 87.8% (teaching) and 86.5% (performing) of children. Children with previous experience performed the manoeuvre in less attempts, less time and more easily than children without experience.

CONCLUSIONS

Measurement of FeNO using NIOX MINO device is technically feasible and acceptable for children and staff in the clinical context of asthma management in primary health care. Previous experience had a positive, learning effect, in teaching and performing the FeNO manoeuvre.