Reproducibility of exhaled nitric oxide measurements in healthy and asthmatic adults and children

Reference ranges for exhaled nitric oxide fraction in healthy Japanese adult population

BACKGROUND

The measurement of the exhaled nitric oxide fraction (FE(NO)) is proposed as a useful marker of airway inflammation. In healthy adults, there have been a few studies of the reference ranges for FE(NO) in Caucasians. A community study in other regions may reveal any possible ethnic differences in the FE(NO) levels.

METHODS

A total of 240 healthy adults aged between 18 to 74 years were recruited from four medical centers in Japan. Current smokers and subjects having a history of atopic disease were not included. FE(NO) was measured using an online electrochemical nitric oxide analyzer according to the current guidelines. The reference ranges for FE(NO) were estimated using two different statistical methods recommended by International Federation of Clinical Chemistry and Laboratory Medicine.

RESULTS

The mean FE(NO) was 16.9 ppb (parts per billion) with a 95% prediction interval (2.5 to 97.5 percentiles) of 6.5 to 35.0 ppb in healthy Japanese adults. Normality assumptions were met for the logarithm-transformed FE(NO). The geometric mean FE(NO) was 15.4 ppb with a mean ± two standard deviations of 6.5 to 36.8 ppb. Age, gender, height, and past smoking history were not associated with the FE(NO) levels.

CONCLUSIONS

The reference ranges for FE(NO) in healthy Japanese adults were similar to those of Caucasians. It seems reasonable that the upper limit of FE(NO) for healthy adults should be set at approximately 36.0 ppb irrespective of ethnic differences.

Chemosensory irritations and pulmonary effects of acute exposure to emissions from oriented strand board

Due to the reduction of air change rates in low-energy houses, the contribution to indoor air quality of volatile organic compounds (VOCs) emitting from oriented strand boards (OSB) has become increasingly important. The aim of this study was to evaluate sensory irritations, pulmonary effects and odor annoyance of emissions from OSB in healthy human volunteers compared to clean air. Twenty-four healthy non-smokers were exposed to clean air and OSB emissions for 2 h under controlled conditions in a 48 m(3) test chamber at three different time points: to fresh OSB panels and to the same panels after open storage for 2 and 8 weeks. Chemosensory irritation, exhaled nitric oxide (NO) concentration, eye blink frequency, lung function and subjective perception of irritation of eyes, nose and throat were examined before, during and after exposure. Additionally, olfactory perception was investigated. Total VOC exposure concentrations reached 8.9 ± 0.8 mg/m(3) for the fresh OSB panels. Emissions consisted predominantly of α-pinene, Δ(3)-carene and hexanal. Two-hour exposure to high VOC concentrations revealed no irritating or pulmonary effects. All the subjective ratings of discomfort were at a low level and the medians did not exceed the expression 'hardly at all.' Only the ratings for smell of emissions increased significantly during exposure in comparison to clean air. In conclusion, exposure of healthy volunteers to OSB emissions did not elicit sensory irritations or pulmonary effects up to a VOC concentration of about 9 mg/m(3). Sensory intensity of OSB emissions in the chamber air was rated as 'neutral to pleasant.'

Dyspnea perception in asthma: role of airways inflammation, age and emotional status

OBJECTIVES

Dyspnea perception in asthmatics differs between subjects. Poor perception is usually associated with increased risk of asthma attack/exacerbation. The advanced stage of the disease and the presence of eosinophilic airways inflammation have been recently recognized as being responsible for poor dyspnea perception. However, few studies are available on this topic.

DESIGN

The aim of this study was to analyse the influence of inflammatory pattern, age and affective status on dyspnea perception in asthmatic subjects.

SUBJECTS AND INTERVENTIONS

Seventy-one consecutive asthmatic patients were recruited and underwent induced sputum, exhaled NO measurement and breath condensate collection. Perception of dyspnea was evaluated as a BORG-VAS/FEV(1) slope before and after the broncho-reversibility test and correlated with the stage of asthma, inflammatory markers, age and depression scale.

RESULTS

Dyspnea perception decreases with the worsening of asthma, with the advance of age and of depression status. Furthermore, airways inflammation plays a key role in the decline of dyspnea perception as proved by the negative correlation observed between inflammatory cells in sputum, exhaled pH and NO and BORG-VAS/FEV(1) slope.

CONCLUSIONS

The results of our study suggested that airways inflammation, depression status, advance age and severity of asthma influence dyspnea perception and suggest a straight control to identify and better manage poor preceptor asthmatics.

Menopausal asthma: a new biological phenotype?

BACKGROUND

Female hormones play an important role in women's lung health, especially in asthma pathophysiology. Although a growing interest has recently been aroused in asthma related to short-term reproductive states, menopausal asthma has been little studied in the past. The aim of the present study was to explore airway inflammation in menopausal asthmatic women in a noninvasive manner.

METHODS

Forty consecutive women with menopausal asthma, 35 consecutive women with premenopausal asthma and 30 age-matched healthy controls were enrolled in the study. Urinary LTE-4, induced sputum inflammatory cells, and exhaled LTE-4, IL-6, pH, and NO levels were measured in all the subjects enrolled.

RESULTS

Women with menopausal asthma showed decreased estradiol concentrations, high sputum neutrophils, and exhaled IL-6. Women with premenopausal asthma presented instead an essentially eosinophilic inflammatory pattern. Higher urine and breath condensate LTE-4 concentrations were found in premenopausal and menopausal asthma compared to controls.

CONCLUSION

Our results substantiate the existence of a new biological phenotype of menopausal asthma that is mainly characterized by neutrophilic airways inflammation and shares several characteristics of the severe asthma phenotype.

Repeatability of exhaled nitric oxide measurements in patients with COPD

The assessment of the presence of eosinophilic airway inflammation may help in predicting the steroid response in subjects with respiratory symptoms. Unlike patients with asthma, only a subset of patients with chronic obstructive pulmonary disease (COPD) benefits from steroid treatment. Fractional exhaled nitric oxide (FENO) is a useful surrogate marker for eosinophilic airway inflammation, but data on the repeatability of FENO measurements in COPD needed for the assessment of significant change are insufficient. The aim of this study was to assess the short-term repeatability of FENO measurement in subjects with moderate to very severe chronic airway obstruction compared to that in healthy subjects. We studied 20 patients with stable COPD and 20 healthy subjects, and determined FENO (flow rate 50 ml s(-1) ) three times: at baseline, 10 min and 24 h after baseline. Spirometry was performed on the first study day after the FENO measurements. The median FENO concentration in patients with COPD was 15·6 ppb, and in healthy subjects, 15·2 ppb. The coefficient of variation (CoV) for 24-h measurements was 12·4% in COPD patients, and 15·9% in healthy subjects. Among COPD patients with global initiative for chronic obstructive lung disease stage 2 disease, the CoV was 13·7%, and among those with stage 3-4 disease, 10·5%. The findings indicate that the short-term repeatability of FENO measurement in patients with moderate to very severe COPD is equally good as in healthy subjects. A change in FENO exceeding 24% is likely to reflect a minimum measurable change in COPD.

Long term performance characteristics of an electrochemical nitric oxide analyser

BACKGROUND

The NIOX MINO(®) is a nitric oxide (FE(NO)) analyser based on electrochemical technology. It includes a replaceable sensor. Quality control procedures are recommended, but regular calibration is not possible. We aimed to evaluate the performance characteristics of the NIOX MINO(®) to identify if reproducibility changed over time, or with different sensors. Also, there are reports that reproducibility of FE(NO) may be reduced in patients with high FE(NO): our secondary aim was to address this issue.

METHODS

Reproducibility in 24 separate sensor-analyser units was calculated on three occasions over two months in 17 patients. These included 9 patients whose FE(NO) was high (mean 80 ppb) and 8 in whom FE(NO) was low (mean 16 ppb).

RESULTS

One device failed quality control testing. For the remaining 23 sensor-analyser combinations, the mean coefficient of variation was 4.0% (range 1.2-7.2%) at baseline, 3.6% (range 2.0-7.0) at one month, and 3.6% (range 1.6-7.6%) at two months. The 95% C.I. for the mean limits of agreement for FE(NO) was ± 4.2 ppb (range 0.9-9.6 ppb), ± 3.8 ppb (range 1.6-6.9 ppb) and ± 3.2 ppb (range 1.2-6.8 ppb) respectively (NS). The limits of agreement exceeded the manufacturer's specifications (± 5 ppb) in 0 devices at baseline, 3 (13%) at one month, and 5 (22%) at two months.

CONCLUSIONS

Reproducibility of FE(NO) using the NIOX MINO(®) was within clinically acceptable limits (± 10 ppb) and was generally stable. However, with time, a proportion of individual sensor-analyser combinations yielded variability outside the manufacturer's specifications.

Acute stress-induced increases in exhaled nitric oxide in asthma and their association with endogenous cortisol

RATIONALE

psychosocial stress is known to influence the pathophysiology of asthma. Although stress has been linked to serum markers of inflammatory activity and exaggerated response to allergen challenge in asthma, few studies have examined inflammatory activity in the airways linked to psychosocial stress alone. Furthermore, although studies have demonstrated lower levels or reactivity of endogenous cortisol in asthma, the association with airway inflammatory activity in stress remains unexplored.

OBJECTIVES

we therefore studied airway inflammation and cortisol response to a standardized laboratory task inducing acute psychosocial stress.

METHODS

airway inflammation by the fraction of exhaled nitric oxide (FeNO) and saliva cortisol were sampled before and up to 45 minutes after experimental challenge with the Trier Social Stress Test in 20 adult patients with asthma and 19 healthy control subjects. Respiratory inductive plethysmography was used to control for changes in ventilatory activity that impact FeNO levels.

MEASUREMENTS AND MAIN RESULTS

FeNO levels were generally higher in patients with asthma than healthy control subjects and salivary cortisol levels were lower. Increases in cortisol levels were observed after the stress protocol in both groups (P < 0.001). FeNO levels at the time of peak cortisol increase after stress were significantly higher than before stress in both groups (P < 0.05). FeNO increases were independent of changes in ventilation. In patients with asthma, higher cortisol levels and stronger increases in cortisol after stress were significantly associated with smaller increases in FeNO (P < 0.05).

CONCLUSIONS

acute psychosocial stress alone increases airway inflammatory markers and this increase is attenuated by stronger stress-related activity of the hypothalamic-pituitary-adrenal axis in asthma.

Increased nitric oxide concentrations in the small airway of older normal subjects

BACKGROUND

There is a paucity of normal-age stratified data for fraction of exhaled nitric oxide (Feno). Our goal was to obtain normal data for large-airway nitric oxide flux (J'awno) and small-airway and/or alveolar nitric oxide concentration (Cano) in nonsmoking, healthy, adult subjects of various ages.

METHODS

In 106 normal volunteer subjects (60 women) aged 55 ± 20 years (mean ± SD), Feno (parts per billion [ppb]) was measured at 50, 100, 150, and 200 mL/s and J'awno (nL/s) and Cano (ppb) were calculated using a two-compartment model with correction for axial nitric oxide (NO) back diffusion. Fourteen older normal subjects were also treated with inhaled corticosteroid (540 μg budesonide bid) for 14 days.

RESULTS

We studied 34 younger normal subjects (17 women) aged 18 to 39 years (younger), 26 middle-aged normal subjects (22 women) aged 40 to 59 years (middle-aged), and 46 older normal subjects (21 women) aged 60 to 86 years (older). Feno at 50 mL/s in the younger group was 21 (14-28) ppb (median, 1-3 interquartile); in the middle-aged group it was 22 (18-30) ppb, and in the older group it was 27 (21-33) ppb, (analysis of variance [ANOVA]) P = .02. For Feno, the younger vs older groups was (Mann-Whitney) P = .03, and Feno in the combined younger and middle-aged groups was 21 (15-29) ppb vs 27 (21-33) ppb, P = .006 for the older group. Corrected J'awno in the younger group was 1.5 (1.0-2.1) nL/s; in the middle-aged group it was 1.4 (1.0-2.0) nL/s, and in the older group it was 1.8 (1.2-2.4) nL/s, (ANOVA) P = .3. Corrected Cano in the younger group was 1.9 (0.8-3.0) ppb; in the middle-aged group it was 2.8 (0.8-5.1) ppb, and in the older group it was 3.9 (1.4-6.6) ppb, (ANOVA) P = .02. Cano in the younger vs older groups was P = .003, and the combined younger and middle-aged group result was 2.0 (0.8-3.8) vs 3.9 (1.4-6.6), P = .01 in the older group. There was no change in NO gas exchange with inhaled corticosteroids.

CONCLUSIONS

In nonsmoking healthy subjects with normal spirometry, Feno at 50 mL/s and Cano increased significantly with age ≥ 60 years, whereas J'awno did not. We suspect the increase in Cano was due to a decrease in capillary blood volume with reduced NO diffusion, which is also reflected in increased Feno. Inhaled budesonide had no anti-NO-mediated inflammatory effect. Age-matched control subjects will be needed in NO comparative studies.

TRIAL REGISTRY

ClinicalTrials.gov; No.: NCT00576069 and NCT00568347; URL: www.clinicaltrials.gov.

Relationship between exhaled nitric oxide and IgE sensitisation in patients with asthma: influence of steroid treatment

INTRODUCTION

The influence of the degree of immunoglobulin E (IgE) sensitisation on the fraction of expired nitric oxide (FE(NO)) in asthma patients being treated with inhaled corticosteroids (ICS) is not well known.

OBJECTIVES

To investigate the relationship between IgE sensitisation and FE(NO), and the effect of a step-up in ICS treatment on this relationship, in patients with allergic asthma.

METHODS

A primary health care centre recruited 20 non-smoking patients with perennial allergic asthma (18 years-50 years, six male) outside the pollen season. At every visit (0, 2, 4, 8 weeks), FE(NO) was measured and an exposure questionnaire was completed. ICS dose was adjusted according to FE(NO) (>or=22 ppb prescribed increase in ICS). Quantitative analyses of serum IgE (eight common aeroallergens) confirmed allergy.

RESULTS

At baseline, FE(NO) and the sum of IgE antibody titres for perennial allergens correlated significantly (r = 0.47, P = 0.04). After a step-up in ICS treatment, this correlation had disappeared. Nine patients had persistently elevated FE(NO) at last visit (mean 35 ppb vs 16 ppb). This group was more frequently exposed to relevant allergens or colds (89% vs 27% of patients, P < 0.05) and had higher IgE antibody titres (perennial allergens) compared with the normalised group (mean 28.9 kU/L vs 10.7 kU/L, P < 0.05).

CONCLUSION

Serum IgE against perennial allergens and FE(NO) correlate in patients with allergic asthma. However, this relationship disappears after a high-dose ICS regimen, suggesting that FE(NO) relates to bronchial inflammation and not IgE levels per se. High degree of IgE sensitisation together with allergen exposure may lead to ICS-resistant airways inflammation.

Effect of fluticasone on markers of inflammation and quality of life in steroid-naive patients with mild asthma

BACKGROUND AND AIMS

Patients with mild asthma may adapt to symptoms that may be neglected at a medical consultation. Despite active airway inflammation, indicating need for treatment symptoms may be poorly perceived and influence on quality of life. The aim was to find out if markers of asthma activity and quality of life are influenced by inhaled steroids in patients who regard themselves as free of symptoms.

METHODS

Seventy steroid-free patients with mild asthma were treated with inhaled fluticasone (250 microg twice daily) or placebo for 3 months in a randomised, double-blind, study. Spirometry with reversibility test, exhaled nitric oxide (NO), bronchial responsiveness to methacholine and eucapnic dry air hyperventilation and quality of life [(Asthma Quality of Life Questionnaire (AQLQ)] were assessed before and after treatment.

RESULTS

Fluticasone, but not placebo, decreased methacholine responsiveness. Bronchial responsiveness to dry air and exhaled NO levels was significantly lowered by fluticasone compared with placebo. Quality-of-life scores were high already before treatment and were not significantly altered by treatment.

CONCLUSION

Treatment with an inhaled steroid in mild asthmatics altered bronchial responsiveness and exhaled NO levels but did not improve quality of life. In mild asthma, there is thus a space for improvement with regard to inflammatory parameters in patients who have only minor symptoms that are not influenced by treatment. In a long-term perspective, the indication for treatment of surrogate markers remains, however, unclear.

Biomarkers in asthma and allergic rhinitis

A biological marker (biomarker) is a physical sign or laboratory measurement that can serve as an indicator of biological or pathophysiological processes or as a response to a therapeutic intervention. An applicable biomarker possesses the characteristics of clinical relevance (sensitivity and specificity for the disease) and is responsive to treatment effects, in combination with simplicity, reliability and repeatability of the sampling technique. Presently, there are several biomarkers for asthma and allergic rhinitis that can be obtained by non-invasive or semi-invasive airway sampling methods meeting at least some of these criteria. In clinical practice, such biomarkers can provide complementary information to conventional disease markers, including clinical signs, spirometry and PC(20)methacholine or histamine. Consequently, biomarkers can aid to establish the diagnosis, in staging and monitoring of the disease activity/progression or in predicting or monitoring of a treatment response. Especially in (young) children, reliable, non-invasive biomarkers would be valuable. Apart from diagnostic purposes, biomarkers can also be used as (surrogate) markers to predict a (novel) drug's efficacy in target populations. Therefore, biomarkers are increasingly applied in early drug development. When implementing biomarkers in clinical practice or trials of asthma and allergic rhinitis, it is important to consider the heterogeneous nature of the inflammatory response which should direct the selection of adequate biomarkers. Some biomarker sampling techniques await further development and/or validation, and should therefore be applied as a "back up" of established biomarkers or methods. In addition, some biomarkers or sampling techniques are less suitable for (very young) children. Hence, on a case by case basis, a decision needs to be made what biomarker is adequate for the target population or purpose pursued. Future development of more sophisticated sampling methods and quantification techniques, such as--omics and biomedical imaging, will enable detection of adequate biomarkers for both clinical and research applications.

Passive smoking is a major determinant of exhaled nitric oxide levels in allergic asthmatic children

BACKGROUND

Fraction of exhaled nitric oxide (FeNO) is considered, by some authors, to be a treatment follow-up parameter in allergic asthmatics. However, factors such as active smoking can influence NO production and must be taken into account in the interpretation of FeNO values. In children, the evidence in favour of an impact of passive smoking (PS) on FeNO values is controversial. The aim of this study was to evaluate the impact of chronic PS on FeNO in allergic asthmatic children.

METHODS

Seventy nontreated allergic asthmatic children over 5 years of age, exposed and unexposed to PS, underwent measurement of FeNO, spirometry, and allergic tests (skin prick tests, total and specific serum IgE, and blood eosinophilia). Children were considered to be exposed to PS when at least 1 cigarette per day was declared to be smoked at home.

RESULTS

Geometric mean FeNO value in 22 children exposed to PS was 26.3 +/- 1.5 ppb vs 56.3 +/- 1.7 ppb in 48 children unexposed (P < 0.001). After adjustment for age, blood eosinophilia, allergic sensitizations, total IgE, dust mite sensitization and asthma severity, multivariate analysis showed that PS exposure was negatively associated with FeNO values (P = 0.0001) and was the primary determinant of FeNO variations.

CONCLUSION

Passive smoking lowers FeNO, and might be a major determinant of FeNO levels in nontreated allergic asthmatic children.

Exercise-induced wheeze: Fraction of exhaled nitric oxide-directed management

BACKGROUND AND OBJECTIVE

Exercise-induced wheeze (EIW) is common. Several treatment options exist. Patients with low fraction of exhaled nitric oxide (F(E)NO) are unlikely to be steroid-responsive and might benefit from non-steroidal therapies. We assessed: the efficacy of cromoglycate, formoterol and montelukast in patients with EIW and low F(E)NO (<35 ppb) in a randomized cross-over trial, and the efficacy of inhaled corticosteroid in a high F(E)NO (>35 ppb) group.

METHODS

Patients had EIW and airway hyperresponsiveness (AHR) to mannitol and/or exercise. Those with low F(E)NO (n = 19) received cromoglycate (20 mg inh. bd + before challenge tests), formoterol (12 microg inh. bd + before challenge tests) and montelukast (10 mg p.o. od), each for 2 weeks. Those with high F(E)NO (n = 20) took inhaled fluticasone (500 microg) daily for 4 weeks. Primary end-points were: 50% reduction in maximum FEV(1) %fall (clinical protection) and decrease in AHR to mannitol.

RESULTS

In patients with low F(E)NO, cromoglycate, formoterol and montelukast significantly decreased AHR to mannitol in 63%, 61% and 47% of patients, respectively. In this group, the magnitude of exercise-induced bronchoconstriction (EIB) was significantly reduced with montelukast and formoterol; between-treatment differences were not significant. Of 6/19 with low F(E)NO and EIB, protection occurred in 67% (cromoglycate), 83% (formoterol) and 50% (montelukast), respectively. In the high F(E)NO group, AHR to mannitol and EIB decreased significantly with fluticasone (P < 0.001, P = 0.005, respectively), and protection occurred in 7/8 (88%) with EIB.

CONCLUSIONS

In patients with EIW and low F(E)NO, the number of 'responders' to cromoglycate, formoterol and montelukast was similar. In a high F(E)NO population the response to inhaled corticosteroid was highly significant and comparable to previous studies.

Inflammation and airway function in the lung periphery of patients with stable asthma

BACKGROUND

An important role for exhaled nitric oxide (NO) measurement could be in the distinction between proximal and peripheral lung contributions to inflammation, with a particular interest for the alveolar lung zone and its implication on airway function.

OBJECTIVE

We aimed to isolate the acinar lung zone contribution to both inflammation and airway function to seek a relationship between them.

METHODS

In 30 patients with asthma with an asthma control test score exceeding 20, indices of conductive and acinar ventilation heterogeneity (Scond, Sacin) were obtained from a multiple breath washout. NO production in the conductive airways (J'aw(NO)), alveolar NO concentration (CA(NO)), and the standard exhaled NO at 50 mL/s (FENO(50)) were obtained from exhaled NO.

RESULTS

Scond was consistently abnormal in all patients with stable asthma, but without any correlation to inflammation abnormality in that compartment (J'aw(NO)). Sacin was particularly abnormal in the asthma subgroup receiving >500 microg budesonide equivalent, and a correlation was found between Sacin and CA(NO) (r = 0.61; P = .015); in this subgroup, a weak association was found between Scond and J'aw(NO) or FENO(50) (r = 0.50; P = .059 for both).

CONCLUSION

The persistent functional abnormality of small conductive airways in patients with stable asthma is largely independent of inflammation as measured by exhaled NO. In the alveolar compartment, a functional correlate of alveolar NO was found in a subgroup of patients with stable asthma on moderate-to-high maintenance doses of inhaled steroids. These patients in particular could benefit from novel therapies specifically aimed at improving airway functionality at the level of the acinar entrance and beyond.

Impact of analysis interval on the multiple exhalation flow technique to partition exhaled nitric oxide

Exhaled nitric oxide (eNO) is elevated in asthmatics and is a purported marker of airway inflammation. By measuring eNO at multiple flows and applying models of eNO exchange dynamics, the signal can be partitioned into its proximal airway [J' aw NO (nl/sec)] and distal airway/alveolar contributions [CA(NO)(ppb)]. Several studies have demonstrated the potential significance of such an approach in children with asthma. However, techniques to partition eNO are variable, limiting comparisons among studies. The objective of this study is to examine the impact of the analysis interval (time or volume) on eNO plateau concentrations and the estimation of J' aw NO and CA(NO). In 30 children with mild to moderate asthma, spirometry and eNO at multiple flows (50, 100, and 200 ml/sec) were measured. The plateau concentration of eNO at each flow was determined using two different methods of analysis: (1) constant time interval and (2) constant volume interval. For both methods of analysis, a two-compartment model with axial diffusion was used to characterize J' aw NO and CA(NO). At a flow of 200 ml/sec, the time interval analysis predicts values for eNO that are smaller than the volume interval analysis. As a result, there are significant differences in CA(NO) between the methods of analysis (volume > time). When using the multiple flow technique to partition eNO, the method of analysis (constant time vs. constant volume interval) significantly affects the estimation of CA(NO), and thus potentially the assessment and interpretation of distal lung inflammation.

A single dose of Sildenafil does not enhance FeNO: a randomised, cross-over and placebo-controlled study

Monitoring of asthma control can be performed with different means including measurement of the concentration of nitric oxide (NO) in exhaled air. Due to its action on the NO-metabolism; we hypothesized that the intake of Sildenafil might augment and falsify the NO-values in exhaled air of subjects taking the drug to treat erectile dysfunction. This randomised, placebo-controlled cross-over study including 10 male non-asthmatic volunteers taking a single dose of 50 mg Sildenafil did not confirm this assumption in non-asthmatic subjects. We cannot think of any reason why asthmatics should behave differently. On the basis of these results, it does not seem necessary to ask asthma patients with elevated NO-values if they had taken any selective inhibitor of the cGMP-specific phosphodiesterase Type 5 as Sildenafil prior to the test.

Non-invasive markers of airway inflammation and remodeling in childhood asthma

To evaluate the relationship between pro-inflammatory and pro-remodeling mediators and severity and control of asthma in children, the levels of IL-8, MMP-9, TIMP-1 in induced sputum supernatants, the number of sputum eosinophils, as well as FeNO, were investigated in 35 asthmatic children, 12 with intermittent (IA) and 23 with moderate asthma (MA), and 9 controls (C). The patients with asthma were followed for 1 yr and sputum was obtained twice during the follow-up. Biomarker levels were correlated with the number of exacerbations. We found that IL-8, MMP-9, TIMP-1 and the numbers of eosinophils in induced sputum, as well as FeNO, were increased in children with IA and MA in comparison to C. The ongoing inflammation was confirmed by increased nuclear p65 NF-kappaB subunit localization in sputum cells. In MA, FeNO measurements, sputum eosinophils and IL-8 levels, positively correlated with the occurrence of disease exacerbations during a 1-yr follow-up. According to FeNO, sputum eosinophils and IL-8 sputum concentrations, and the number of exacerbations, two distinct phenotypes of MA were identified. This study shows that the presence of bronchial inflammation is detectable in the airways of some IA, as well as in the airways of MA, despite the regular ICS treatment. This study also proposes the need to perform large prospective studies to confirm the importance of measuring specific biomarkers in induced sputum, concomitantly to FeNO analyses, to assess sub-clinical airway inflammation and disease control in children with asthma.

Comparability of a hand-held nitric oxide analyser with online and offline chemiluminescence-based nitric oxide measurement

Practicability is crucial for successful implementation of fractional exhaled nitric oxide (FeNO) measurement into asthma management. The study aimed at comparing a conventional chemiluminescence NO analyser (EcoMedics) with a hand-held device (NIOX MINO) and offline FeNO measurement using a commercially available system in an unselected cohort of children aged 6-16 yr. A secondary objective was to confirm FeNO stability over time in 15 samples from adult volunteers obtained using the offline system. Sixty-six children (mean +/- s.d. age 11.8 +/- 3.0 yr) underwent single breath FeNO measurement in triplets with each device. Offline collected FeNO was measured after offline breath collection into a Mylar balloon and subsequent analysis using the chemiluminescence NO analyser. Variability and between-method agreement were assessed, and stability over time within the Mylar balloons was tested by repeated hourly measurements. FeNO levels ranged from 2 to 113 p.p.b. Intra-class correlation was excellent (r = 0.98, p < 0.001 for each pair). Bland-Altman plots and back-transformation of logarithmic mean differences revealed fair agreement between methods. Stability over time was confirmed over 10 h both at room temperature and when stored under cooling conditions. FeNO values obtained using the chemiluminescence NO analyser, the portable NIOX MINO system and the offline collection technique show between-method agreement within clinically acceptable range.

Exhaled nitric oxide in diagnosis and management of respiratory diseases

The analysis of biomarkers in exhaled breath constituents has recently become of great interest in the diagnosis, treatment and monitoring of many respiratory conditions. Of particular interest is the measurement of fractional exhaled nitric oxide (FENO) in breath. Its measurement is noninvasive, easy and reproducible. The technique has recently been standardized by both American Thoracic Society and European Respiratory Society. The availability of cheap, portable and reliable equipment has made the assay possible in clinics by general physicians and, in the near future, at home by patients. The concentration of exhaled nitric oxide is markedly elevated in bronchial asthma and is positively related to the degree of esinophilic inflammation. Its measurement can be used in the diagnosis of bronchial asthma and titration of dose of steroids as well as to identify steroid responsive patients in chronic obstructive pulmonary disease. In primary ciliary dyskinesia, nasal NO is diagnostically low and of considerable value in diagnosis. Among lung transplant recipients, FENO can be of great value in the early detection of infection, bronchioloitis obliterans syndrome and rejection. This review discusses the biology, factors affecting measurement, and clinical application of FENO in the diagnosis and management of respiratory diseases.

Exhaled nitric oxide levels in asthma: Personal best versus reference values

BACKGROUND

Factors affecting the fraction of nitric oxide in exhaled air (FE(NO)) are multiple. Interpreting values when assessing airways disease may be problematic. Clinically optimum levels have not been defined.

OBJECTIVES

We aimed to establish the relationship between predicted values for FE(NO) obtained from equations by Olin et al, Travers et al, and Dressel et al, and normalized levels after oral prednisone. We also compared postprednisone FE(NO) levels with those obtained during optimized treatment with inhaled fluticasone.

METHODS

Data were obtained before and after a trial of oral prednisone (30mg/d for 14 days), and also from a previously published study in which patients had their dose of inhaled corticosteroid adjusted using either FE(NO) or symptoms/lung function to optimize treatment.

RESULTS

Seventy-three patients completed the study. The geometric mean FE(NO) after prednisone (17.7 parts per billion [ppb]; 95% CI, 15.5-20.2) was significantly lower than mean FE(NO) at the optimized fluticasone dose (20.2 ppb; 95% CI, 17.1-23.8; P=.04) and at loss of control (27.6 ppb; 95% CI, 22.8-33.4; P < .001). FE(NO) levels after prednisone did not differ significantly from the predicted values of Olin et al (16.8 ppb, 95% CI, 16.0-17.5; P=.44), but were significantly lower than values of Travers et al (predicted, 21.5 ppb; 95% CI, 20.9-22.2; P=.005) and Dressel et al (predicted, 27.8 ppb; 95% CI, 26.7-28.9; P < .001).

CONCLUSIONS

Optimum FE(NO) levels are best established by using oral rather than inhaled steroid treatment, and these approximate to predicted values from the reference equation by Olin et al. However, at optimized doses of inhaled corticosteroid, although FE(NO) levels were higher than predicted, asthma was well controlled. Targeting FE(NO) on reference values is not justified.

Fractional exhaled nitric oxide in asthma: an update

In asthma, clinical symptoms and lung function are insensitive in reflecting the underlying airway inflammation, and monitoring of this process has only recently become available. Fractional exhaled nitric oxide (Fe(NO)) is now recognized as a reliable surrogate marker of eosinophilic airway inflammation and offers the advantage of being completely non-invasive and very easy to obtain. This review summarizes the clinical use of Fe(NO) in asthma. It covers the relationship between Fe(NO) and the underlying eosinophilic inflammation, the pathophysiology and production of Fe(NO), technical aspects of Fe(NO) measurement and potential confounding factors in interpreting levels. Fe(NO) reference values and the role of Fe(NO) in asthma assessment, diagnosis and management are also discussed.

Adenosine infusion attenuates soluble RAGE in endotoxin-induced inflammation in human volunteers

AIM

To evaluate possible anti-inflammatory effects of pre-treatment with adenosine in a human experimental inflammatory model.

METHODS

The study design was double-blind, crossover, placebo-controlled and randomized. In the Intensive Care Unit of a university hospital, 16 healthy male volunteers were treated for 5.5 h with infusions of adenosine 40 microg kg(-1) min(-1) or placebo. Thirty minutes after the start of adenosine or placebo, 2 ng kg(-1)E-Coli endotoxin was administered. Heart rate, body temperature, blood pressure, plasma cytokines (TNF-alpha, IL-6 and IL-10), soluble RAGE and resistin, exhaled nitric oxide and nitrite/nitrate in urine were determined.

RESULTS

Endotoxin elicited the expected clinical signs of an inflammatory reaction (tachycardia, fever) and led to prominent release of the cytokines studied (P < 0.001). Resistin in plasma increased after endotoxin (P < 0.001). After placebo treatment, soluble RAGE (sRAGE) in plasma increased 5 h after the endotoxin challenge (P < 0.001) but not after adenosine. After placebo, orally exhaled NO increased with a peak at 4 h (P < 0.001), although there was no statistically significant difference between the two treatments. Nitrite/nitrate in urine (n = 11) did not differ between adenosine and placebo treatments.

CONCLUSION

In conclusion, adenosine infusion starting before endotoxin challenge in humans attenuated sRAGE significantly but otherwise had no clear anti-inflammatory effect. Adenosine as a potential anti-inflammatory treatment in humans needs further study, including use of higher doses. The mechanism underlying the effect of adenosines on sRAGE remains unknown.

Measurement of nitric oxide and 8-isoprostane in exhaled breath of children with atopic eczema

BACKGROUND

Children with atopic eczema (AE) are at risk of developing asthma. Airway inflammation has been shown to be present before the onset of clinical asthma. Increased exhalation (forced expiration; FE) of nitric oxide (FE(NO)) and 8-isoprostane seems to be a feature of bronchial inflammation in people with asthma.

AIM

To determine whether the exhalation of these two molecules is increased in children with eczema, even in the absence of overt asthma.

METHODS

In total, 21 children with AE were recruited and compared with healthy controls. A questionnaire was completed to identify respiratory symptoms compatible with asthma. The severity of AE was graded clinically. Spirometry, FE(NO) measurements and exhaled breath condensate collection for 8-isoprostane were performed.

RESULTS

The mean level of 8-isoprostane was similar for children with AE (2.33 +/- 4.76 pg/mL) and controls (3.37 +/- 3.43). FE(NO) was increased in children with AE (mean 64.97 parts per billion) compared with the normal range, even in the absence of respiratory symptoms and in the presence of normal lung function.

CONCLUSIONS

FE(NO) but not 8-isoprostane levels in exhaled breath condensate are higher in children with AE without asthma. Our finding may indicate a predictive role for FE(NO) for the development of asthma.

[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.

Role of add-on zileuton on total exhaled, large airway, and small airway/alveolar nitric oxide in moderate-severe persistent adult asthmatics on fluticasone 250 microg/Salmeterol 50 microg

BACKGROUND

Measuring non-invasive exhaled biomarkers of inflammation may be important in monitoring asthma therapy.

OBJECTIVE

Evaluate exhaled nitric oxide with add-on leukotriene synthesis inhibitor in moderate-severe persistent asthmatics on combination controllers.

METHODS

In a non-randomized, non-placebo, single-blind, fixed sequence, pilot study, we evaluated 22 non-smoking, stable, moderate-severe adult asthmatics on maintenance inhaled fluticasone 250 microg/salmeterol 50 microg (F/S) via MDI bid> or =1 yr, with add-on oral zileuton 600 mg qid. Exhaled fractional nitric oxide (FENO) gas exchange, large airway NO, small airway/alveolar NO concentration (CANO), Juniper score and lung function were measured. Asthmatics were studied at baseline only on F/S bid (visit 1), on F/S bid pre and 2 h post first dose zileuton 600 mg (visit 2), and post 4 weeks (visit 3) F/S bid plus zileuton 600 mg qid. Values were compared at each visit and to healthy non-smoking age matched healthy controls with normal lung function.

RESULTS

Three asthmatics stopped zileuton prematurely (headache and/or nausea) and 19 (12F) age 55+/-17 yr (mean+/-SD) completed the 4-week study. Baseline forced expiratory lung volume in 1 sec (FEV(1)) was 1.6+/-0.7L (53+/-19% pred) (mean+/-SD), FEV(1) over FVC ratio was 64+/-11% and post 180 microg albuterol FEV(1) was 1.8+/-0.7L (56+/-21% pred), and FEV(1) over FVC ratio was 67+/-12%. Baseline Juniper scores were mild (10+/-10) and similar (p=ns) at all visits. Baseline FENO@50 mL/s was 48+/-27 ppb (mean+/-SD), and FENO@100 mL/s was 29+/-16ppb, and were similar (p=ns) at all visits. Large airway NO flux was 2.0+/-1.3 nL/s (52% asthmatics abnormal) and small airway/alveolar NO was 8.0+/-4.0 ppb (79% asthmatics abnormal) and were similar (p=ns) at all visits. Compared to baseline, post 26+/-6 days Zileuton, mean FEV(1) (L)% predicted increased 3.3% predicted (p=0.03), and FEV(1) over FVC ratio increased 2.2% (p=0.03).

CONCLUSION

In stable, moderate-severe persistent adult asthmatics, large airway NO flux, small airway/alveolar CANO, and Juniper airway scores, were not significantly different on F/S bid vs F/S bid plus Zileuton for 4 weeks, despite significant small increase in FEV(1) over FVC ratio and FEV(1)% predicted.

Comparing 6 and 10 sec exhalation time in exhaled nitric oxide measurements in children

Standard exhalation time for Fractional exhaled Nitric Oxide (FeNO) measurements is 10 sec but this is difficult for young children. Recommended exhalation time for children is 6 sec, but this was never substantiated in literature. We aimed to investigate the agreement between FeNO values measured with exhalation times of 6 and 10 sec and the preference of children for either method. The study population comprised children aged 5-17 years visiting the Pediatric Pulmonology outpatient clinic. FeNO values, measured during 6 (FeNO-6) and 10 (FeNO-10) sec (random order) using the single-breath online (SBOL) technique, were compared. Preferences for exhalation times were related to FVC values. Ninety-eight children (mean age 10.6 years) were included. Median FeNO-6 (15.2 ppb) and FeNO-10 (13.6 ppb) did not differ significantly (P = 0.259). Mean difference between FeNO-6 and FeNO-10 was -0.3 ppb, limits of agreement ranging from -5.8 ppb to +5.3 ppb. Sixty percent of children with a Forced Vital Capacity (FVC) less than 3 L preferred the FeNO-6 method. We found good agreement between FeNO-6 and FeNO-10, so they can be used interchangeably. An exhalation time of 6 sec was preferred by the majority of subjects with a FVC below 3 L.

Diagnosing asthma in general practice with portable exhaled nitric oxide measurement--results of a prospective diagnostic study: FENO < or = 16 ppb better than FENO < or =12 ppb to rule out mild and moderate to severe asthma [added]

BACKGROUND

To evaluate the sensitivity, specificity and predictive values of fractional exhaled nitric oxide (FENO) for the diagnosis of asthma in general practice.

METHODS

Prospective diagnostic study with 160 patients attending 10 general practices for the first time with complaints suspicious of obstructive airway disease (OAD). Patients were referred to a lung function laboratory for diagnostic investigation. The index test was FENO measured with a portable FENO analyser based on electrochemical sensor. The reference standard was the Tiffeneau ratio (FEV1/VC) as received by spirometric manoeuvre and/or results of bronchial provocation. Bronchial provocation with methacholine was performed to determine bronchial hyper-responsiveness (BHR) in the event of inconclusive spirometric results.

RESULTS

88 (55%) were female; their average age was 43.9 years. 75 (46.9%) patients had asthma, 25 (15.6%) had COPD, 8 (5.0%) had an overlap of COPD and asthma, and 52 (32.5%) had no OAD. At a cut-off level of 46 parts per billion (ppb) (n = 30; 18.8%), sensitivity was 32% (95%CI 23-43%), specificity 93% (95%CI 85-97%), positive predictive value (PPV) 80% (95%CI 63-91%), negative predictive value (NPV) 61% (95%CI 52-69%) when compared with a 20% fall in FEV1 from the baseline value (PC20) after inhaling methacholine concentration

CONCLUSION

Asthma could be ruled in with FENO > 46 ppb. Mild and moderate to severe asthma could be ruled out with FENO Collapse

Key Words Collapse

MESH Headings

• Adult
• Aged
• Asthma/diagnosis
• Asthma/metabolism
• Asthma/physiopathology
• Breath Tests/instrumentation
• Bronchial Hyperreactivity
• Bronchial Provocation Tests
• Bronchoconstrictor Agents
• Electrochemical Techniques/instrumentation
• Equipment Design
• Exhalation
• Family Practice
• Female
• Forced Expiratory Volume
• Germany
• Humans
• Lung/physiopathology
• Male
• Methacholine Chloride
• Middle Aged
• Netherlands
• Nitric Oxide/analysis
• Predictive Value of Tests
• Prospective Studies
• Sensitivity and Specificity
• Severity of Illness Index
• Vital Capacity
• Young Adult

Collapse

Grants Collapse

Affiliation(s)

Antonius Schneider Department of General Practice and Health Services Research, University Hospital, University of Heidelberg, Heidelberg, Germany
Lisa Tilemann Department of General Practice and Health Services Research, University Hospital, University of Heidelberg, Heidelberg, Germany
Tjard Schermer Department of Primary Care Medicine, Radboud University Nijmegen Medical Centre, Nijmegen, the Netherlands
Lena Gindner Department of General Practice and Health Services Research, University Hospital, University of Heidelberg, Heidelberg, Germany
Gunter Laux Department of General Practice and Health Services Research, University Hospital, University of Heidelberg, Heidelberg, Germany
Joachim Szecsenyi Department of General Practice and Health Services Research, University Hospital, University of Heidelberg, Heidelberg, Germany
Franz Joachim Meyer Department of Cardiology, Pulmonology and Angiology, Medical Centre, University of Heidelberg, Heidelberg, Germany

Collapse

Biomarkers in asthma

PURPOSE OF REVIEW

The purpose of this review is to highlight seminal and current literature that informs our understanding of the clinical and investigative utility of biomarkers in asthma. Biomarkers derive from a variety of sources [bronchiolar lavage (BAL), sputum, exhaled breath, and blood], and have widely variant performance characteristics, and applicability.

RECENT FINDINGS

Increasing attention is given to biomarkers in exhaled breath, both gaseous (exhaled nitric oxide) and higher molecular weight moieties [in exhaled breath condensate (EBC)]. Current research in EBC analysis has focused on validation, standardization, and technical considerations, whereas research on exhaled nitric oxide (ENO) has moved to testing its predictive value in clinical situations. The use of advanced biostatistical techniques, and combinatorial analyses has led to additional advances in the utility of biomarkers.

SUMMARY

To date, the best validated, and best performing biomarkers for clinical asthma appear to be measures of inflammation in induced sputum, and measures of ENO. Some trials using ENO appear particularly promising for early clinical use. EBC metrics are at present too inchoate for clinical purposes. However, not all important clinical and research questions can be addressed with sputum, EBC, or ENO metrics, leaving an important place for BAL, bronchial biopsy, and perhaps EBC measurements in the research arena.

Measurement of nasal nitric oxide: evaluation of six different sampling methods

BACKGROUND

Specific guidelines are developed for the measurement of bronchial FE(NO), however, nasal nitric oxide (nNO) measurement is not standardised yet, resulting in divergent nNO values. This study compares six different sampling methods for nNO as described in the literature, to analyse their outcome and short term and long term reproducibility.

DESIGN

nNO concentrations were measured in 38 healthy subjects. Each subject performed nNO measurements during tidal breathing (nNO-TB), single breath quiet exhalations (nNO-QE), QE with oral exhalation against a resistance (nNO-QE + R), breath holding (nNO-BH) and during single-breath humming exhalations at 128 and 440 Hz (nNO-HE(128) and nNO-HE(440), respectively). To assess short term and long term reproducibility all manoeuvres were repeated after one and 24 h.

RESULTS

Lowest values were found during quiet exhalation (mean nNO-QE was 364 p.p.b., SEM 27). Methods in which there is turbulence of nasal flow (as in TB, HE(128) and HE(440)) result in higher nNO levels. Highest values were found in methods with decreased nasal flow [when there is no nasal flow as in BH or when the velum is closed as in QE + R: mean nNO 763 p.p.b. (SEM 61)]. NNO during humming at 440 Hz was significantly higher than at 128 Hz (P < 0.01). The within-subject coefficient of variation of repeated measurements was lowest during humming and breath holding, 3.4 and 3.8%, respectively. Concerning short term and long term reproducibility, best agreement is reached with humming and second best with breath holding.

CONCLUSIONS

Different methods result in different levels and reproducibility of nNO. In regard to this, methods of humming and breath holding are recommended for standardised measurement of nasal NO.

Analysis of single-breath profiles of exhaled nitric oxide in children with allergy and asthma: guideline-derived plateau concentrations compared to results of automatic evaluation by two analyzers

Current guidelines recommend the single-breath measurement of fractional concentration of exhaled nitric oxide (FE(NO)) at the expiratory flow rate of 50 mL/s as a gold standard. The time profile of exhaled FE(NO) consists of a washout phase followed by a plateau phase with a stable concentration. This study performed measurements of FE(NO) using a chemiluminescence analyzer Ecomedics CLD88sp and an electrochemical monitor NIOX MINO in 82 children and adolescents (44 males) from 4.9 to 18.7 years of age with corticosteroid-treated allergic rhinitis (N = 58) and/or asthma (N = 59). Duration of exhalation was 6 seconds for children less than 12 years of age and 10 seconds for older children. The first aim was to compare the evaluation of FE(NO)-time profiles from Ecomedics by its software in fixed intervals of 7 to 10 seconds (older children) and 2 to 4 seconds (younger children) since the start of exhalation (method A) with the guideline-based analysis of plateau concentrations at variable time intervals (method B). The second aim was to assess the between-analyzer agreement. In children over 12 years of age, the median ratio of FE(NO) concentrations of 1.00 (95% CI: 0.99-1.02) indicated an excellent agreement between the methods A and B. Compared with NIOX MINO, the Ecomedics results were higher by 11% (95% CI: 1-22) (method A) and 14% (95% CI: 4-26) (method B), respectively. In children less than 12 years of age, the FE(NO) concentrations obtained by the method B were 34% (95% CI: 21-48) higher and more reproducible (p < 0.02) compared to the method A. The Ecomedics results of the method A were 11% lower (95% CI: 2-20) than NIOX MINO concentrations while the method B gave 21% higher concentrations (95% CI: 9-35). We conclude that in children less than 12 years of age, the guideline-based analysis of FE(NO)-time profiles from Ecomedics at variable times obtains FE(NO) concentrations that are higher and more reproducible than those from the fixed interval of 2 to 4 seconds and higher than NIOX MINO concentrations obtained during a short exhalation (6 seconds). The Ecomedics FE(NO) concentrations of children more than 12 years of age calculated in the interval of 7 to 10 seconds represent plateau values and agree well with NIOX MINO results obtained during a standard 10-second exhalation.

Effect of fluticasone 250 microg/salmeterol 50 microg and montelukast on exhaled nitric oxide in asthmatic patients

BACKGROUND

Monitoring noninvasive biomarkers of inflammation is an important adjunct in asthma therapy.

OBJECTIVE

The goal of the present study was to identify airway and alveolar site(s) of inflammation using exhaled nitric oxide (NO) as a marker in asthmatic patients, and to evaluate the NO response to maintenance fluticasone 250 microg/salmeterol 50 microg (F/S) and add-on montelukast 10 mg (M).

METHODS

Thirty (24 women) nonsmoking, mild to moderate asthmatic patients were studied, mean age (+/- SD) 43+/-9 years, treated with F/S for more than one year. All were clinically stable for longer than eight weeks and had not taken oral corticosteroids and/or leukotriene antagonists for eight weeks before the present study. Spirometry, Juniper asthma symptom score, fractional exhaled NO (FENO) 100 mL/s, bronchial NO and alveolar NO concentration (CANO) were measured in a single-blind, nonrandomized crossover study.

PROTOCOL

Visit 1: baseline F/S; visit 2: after four weeks of F/S plus M; visit 3: after four weeks of S plus M; and visit 4: after four weeks of S only. Values in asthmatic patients were also compared with 34 nonsmoking age-matched healthy controls with normal lung function.

RESULTS

After 180 microg aerosolized metered dose inhaler albuterol, the forced expiratory volume in 1 s at baseline was 2.6+/-0.8 L (86%+/-16% of the predicted value) and the forced expiratory volume in 1 s over the forced vital capacity was 77%+/-9% (mean +/- SD), and was similar at visits 2 to 4. Juniper scores were mildly abnormal at visits 1 to 3, but significantly worse (P=0.03) at visit 4 versus visits 1 to 3. FENO values at visits 1 to 3 were similar but significantly increased (P=0.007) at visit 4. Bronchial NO was higher (P=0.03) at visit 4, versus visits 1 and 2, and was no different at visit 3. Compared with the healthy subjects, FENO and bronchial NO values were abnormal (greater than the normal mean plus 2 SD) in 33% of asthmatic patients at visits 1 to 3. CANO was similar for visits 1 to 4. CANO was abnormal (greater than the normal mean + 2 SD) in 20% of asthmatic patients.

CONCLUSION

In clinically stable asthmatic patients, despite controller treatment including moderate-dose inhaled corticosteroids and add-on M, 33% of mild to moderate asthmatic patients have ongoing nonsuppressed bronchial sites of increased NO production, compared with healthy control subjects. These controllers have no effect on CANO, which was abnormal in 20% of the asthmatic patients studied. The addition of add-on M to baseline moderate-dose inhaled corticosteroid did not further reduce total exhaled, bronchial and/or alveolar NO production.

The use of exhaled nitric oxide in the management of asthma

It has recently become clear that airways disease associated with eosinophilic airway inflammation, but not other patterns of inflammation, is closely associated with favourable short-and long-term responses to corticosteroid therapy, irrespective of the clinical context in which it occurs. Moreover, a raised exhaled nitric oxide (FE(NO)) is a reasonable marker of eosinophilic airway inflammation, which has a number of advantages as a diagnostic and monitoring tool. In this review we outline essential background information on the use of FE(NO) in clinical practice and discuss some recent work evaluating the clinical value of this technique.

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.

Urinary eosinophil protein X in children with atopic asthma

The aim of this study was to investigate the relationship between urinary eosinophil protein X (uEPX) and asthma symptoms, lung function, and other markers of eosinophilic airway inflammation in asthmatic school children.

METHODS

A cross-sectional study was performed in 180 steroid dependent atopic children with stable moderately severe asthma, who were stable on 200 or 500 microg of fluticasone per day. uEPX was measured in a single sample of urine and was normalized for creatinine concentration (uEPX/c). Symptom scores were kept on a diary card. FEV1 and PD20 methacholine were measured. Sputum induction was performed in 49 and FE(NO) levels measured in 24 children.

RESULTS

We found an inverse correlation between uEPX/c and FEV1 (r = -.20, P = .01) and a borderline significant correlation between uEPX/c and PD20 methacholine (r = -.15, P = .06). Symptom score, %eosinophils and ECP in induced sputum and FE(NO) levels did not correlate with uEPX/c.

CONCLUSION

uEPX/c levels did not correlate with established markers of asthma severity and eosinophilic airway inflammation in atopic asthmatic children.

Feasibility and interpretation of FE(NO) measurements in asthma patients in general practice

BACKGROUND

Exhaled NO (FE(NO)) is a useful biomarker for the monitoring of asthma control and response to therapy. However, there is a lack of data on FE(NO) levels and their interpretation in Primary Care asthma population depending on their treatment and smoking habit. Besides, the majority of current FE(NO) tests have been done by stationary chemiluminescence analysers whose use is limited to research laboratories.

METHODS

FE(NO) measurements by the novel hand-held NO monitoring device (NIOX MINO) were made in 96 asthma patients (32 males, mean age 53+/-12) at five local General Practices during their scheduled 15-20 min visits for lung function assessment.

RESULTS

Success rate was 78% and the intra-subject coefficient of variation was 8.7%. Inhaled corticosteroid treatment had an overall reducing effect on the FE(NO) value (30.5 [19.8-49.8]) vs. patients not on the ICS (26.5 [19-94]) (p<0.044). FE(NO) levels in the ICS treated current or ex-smokers group of patients were still significantly above the normal values (p<0.0001). FE(NO) levels were similar in patients receiving ICS whether there were current, ex-smokers or non-smokers. The highest FE(NO) levels (94 [15.8-151]) were found in asthmatic current smokers and not receiving treatment with ICS. The most "normalised" FE(NO) levels (35.3 [13.5-35.3]) were seen in ex-smokers.

CONCLUSIONS

FE(NO) measurements performed with a new hand-held monitoring device are reproducible and feasible in General Practice in the majority of patients of different ages and asthma severities. A high percentage of patients with different severities of asthma and regardless of their treatment with ICS and current smoking habit (current and/or ex-smokers) had highly elevated FE(NO) values, suggesting that their current therapy was possibly insufficient to control the underlying degree of airway inflammation and asthma symptoms.

Exhaled nitric oxide measurement is useful for the exclusion of nonasthmatic eosinophilic bronchitis in patients with chronic cough

BACKGROUND

Nonasthmatic eosinophilic bronchitis (NAEB) is an important cause of chronic cough, and it can be diagnosed by an induced-sputum (IS) examination. However, an IS examination is a complex and time-consuming procedure, and it has limited clinical application. This study aimed to evaluate the role of exhaled nitric oxide (NO) for the investigation of chronic cough, especially of NAEB.

METHODS

Two hundred eleven nonsmoking patients with a cough lasting > 3 weeks were enrolled in the study. The patients were examined and investigated with conventional diagnostic tools, including an IS examination. Exhaled NO was measured by a chemoluminescent analyzer.

RESULTS

One hundred seventeen patients with adequate IS results were analyzed: asthma, n = 14; NAEB, n = 21; and "others," n = 82. Exhaled NO and IS eosinophils were significantly higher in the asthma group and NAEB group than in the others group. Exhaled NO and IS eosinophils were significantly correlated in the asthma and NAEB groups. In the nonasthmatic group, the sensitivity and specificity of exhaled NO for detecting NAEB, using 31.7 parts per billion as the exhaled NO cutoff point, were 86% and 76%, respectively. Positive and negative predictive values were 47% and 95%, respectively, and positive and negative likelihood ratios were 3.51 and 0.19, respectively.

CONCLUSION

We concluded that exhaled NO measurement may be useful as part of the initial evaluation for chronic cough, especially for the exclusion of NAEB. A low level of exhaled NO suggested little likelihood of NAEB for the nonasthmatic patients with chronic cough.

The use of fraction of exhaled nitric oxide in pulmonary practice

The measurement of the fractional concentration of exhaled nitric oxide (FeNO) is a convenient, noninvasive, point-of-service office test for airway inflammation. The first half of this practice management review presents the methodological, interpretative, and clinical applications of FeNO. The second half discusses practical management issues, including current and future technology, equipment specifications, US Food and Drug Administration regulations, cost, current procedural terminology coding, and reimbursement. The measurement of FeNO is helpful in the diagnosis of asthma. It is predictive of a response to inhaled corticosteroids (ICSs). Monitoring FeNO is useful in maintaining asthma control by allowing the assessment of adherence to medication and dose titration of ICSs. An elevated level of FeNO is predictive of asthma relapse following corticosteroid withdrawal especially in children. The advances in technology, ease of use, and clinical utility will lead to greater availability, acceptance, and routine application in the care of asthma.

Airway responsiveness and inflammation in adolescent elite swimmers

BACKGROUND

Whereas increased airway hyperresponsiveness (AHR) and airway inflammation are well documented in adult elite athletes, it remains uncertain whether the same airway changes are present in adolescents involved in elite sport.

OBJECTIVE

To investigate airway responsiveness and airway inflammation in adolescent elite swimmers.

METHODS

We performed a cross-sectional study on adolescent elite swimmers (n = 33) and 2 control groups: unselected adolescents (n = 35) and adolescents with asthma (n = 32). The following tests were performed: questionnaire, exhaled nitric oxide (FeNO), spirometry, induced sputum, methacholine challenge, eucapnic voluntary hyperpnea (EVH) test, and exhaled breath condensate pH.

RESULTS

There were no differences in FeNO, exhaled breath condensate pH, cellular composition in sputum, or prevalence of AHR to either EVH or methacholine among the 3 groups. When looking at airway responsiveness as a continuous variable, the swimmers were more responsive to EVH than unselected subjects, but less responsive to methacholine compared with subjects with asthma. We found no differences in the prevalence of respiratory symptoms between the swimmers and the unselected adolescents. There was no difference in FeNO, cellular composition of sputum, airway reactivity, or prevalence of having AHR to methacholine and/or EVH between swimmers with and without respiratory symptoms.

CONCLUSION

Adolescent elite swimmers do not have significant signs of airway damage after only a few years of intense training and competition. This leads us to believe that elite swimmers do not have particularly susceptible airways when they take up competitive swimming when young, but that they develop respiratory symptoms, airway inflammation, and AHR during their swimming careers.

[Agreement between two devices for measuring exhaled nitric oxide]

BACKGROUND

Measurement of fractional exhaled nitric oxide (FENO) is a non-invasive marker of eosinophilic airway inflammation that can be useful in asthma diagnosis and control, as well as in treatment monitoring.

OBJECTIVE

We studied the correlation between two techniques for measuring FENO: the chemiluminescence-based analyzer (NIOX, Aerocrine, Sweden) and a new portable electrochemical sensor-based analyzer (NIOX-MINO, Aerocrine).

MATERIAL AND METHODS

FENO was measured by the single breath on-line method. In all children, three consecutives measurements were obtained with NIOX, with a maximum of six attempts, and the arithmetic mean was calculated. Next, using NIOX-MINO, a single measurement was made successively in each of the children. The variables analyzed were sex, age, height, weight, diagnosis, treatment, NIOX-MINO value, mean of three values obtained with NIOX and the NO elimination rate (nL/min). For the statistical analysis, the Bland-Altman plot was used to compare the means and the differences between measurements of FENO from NIOX and NIOX-MINO. The agreement between the two analyzers was estimated by Cohen's Kappa statistic.

RESULTS

Thirty children were included, 14 (46.67%) boys and 16 (53.33%) girls. The mean age was 11.3+/-3.09 years. All of the children successfully performed the measurements with two analyzers. The relationship between the means and the differences in the values obtained with NIOX-MINO and NIOX were statistically significant (p<0.005). In addition, Cohen's Kappa statistic (0.78) suggested a high degree of agreement between the results obtained with the two devices.

CONCLUSIONS

The two analyzers, NIOX-MINO and NIOX, were not equivalent. There was good agreement between the FENO values measured with the two devices. Measurement of FENO with the portable electrochemical sensor-based analyzer (NIOX-MINO) is valid and feasible in children older than 5 years.

[Exhaled nitric oxide in children: a noninvasive marker of airway inflammation]

This article is an academic review of the application in children of the measurement of fractional exhaled nitric oxide (FENO). We outline the joint American Thoracic Society/European Respiratory Society recommendations for online measurement of FENO in both cooperating children and children unable to cooperate, offline measurement with uncontrolled exhalation flow rate, offline measurement with controlled exhalation flow rate using a dynamic flow restrictor, and offline measurement during tidal breathing in children unable to cooperate. This is followed by a review of the normal range of values for single-breath online measurements obtained with a chemiluminescence FENO analyzer (geometric mean, 9.7 parts per billion [ppb]; upper limit of the 95% confidence interval, 25.2 ppb). FENO values above 17 ppb have a sensitivity of 81% and a specificity of 80% for predicting asthma of an eosinophilic phenotype. We discuss the response of FENO values to anti-inflammatory treatment and the use of this marker in the management of asthma. Results obtained with chemiluminescence and portable electrochemical analyzers are compared. The portable devices offer the possibility--in children over 5 years of age--of accurate and universal monitoring of exhaled nitric oxide concentrations, an emerging marker of eosinophilic inflammation in asthma that facilitates diagnosis, monitoring of disease progression, and assessment of response to therapy.

Exhaled nitric oxide in the diagnosis and management of asthma

PURPOSE OF REVIEW

Gaseous nitric oxide is present in our exhaled breath and may be a biomarker for asthma. The purpose of the present paper is to review recent studies that have explored the potential of exhaled nitric oxide as a biomarker for asthma diagnosis and treatment.

RECENT FINDINGS

The upper limit of exhaled nitric oxide has been described in several populations, using a standard methodology. Measurements of exhaled nitric oxide have good specificity but relatively poor sensitivity for diagnosing asthma. The inter- and intra-subject variability of exhaled nitric oxide values in asthmatics remains uncertain. Clinical trials have used exhaled nitric oxide to guide steroid treatment in asthmatics with varied success. The greatest success is in studies where inhaled corticosteroids are reduced and/or withdrawn in stable asthmatics. These pioneering clinical trials have given insight into how exhaled nitric oxide might be a useful index of control of eosinophilic airway inflammation.

SUMMARY

Measurements of exhaled nitric oxide have the potential to be useful in the management of allergic asthma and the answers to a number of important questions are awaited.

Identifying the components of asthma health status in children with mild to moderate asthma

BACKGROUND

Weak and inconsistent correlations between measurements of asthma health status suggest that the disease is composed of nonoverlapping components.

OBJECTIVE

Factor analysis was used to explore the relationships between measures of asthma morbidity and to identify heterogeneous components of asthma health status in children 5 to 12 years old. Results were compared across time (baseline and 48-month visit) and treatment arms.

METHODS

Analyses were conducted in 7 different study windows in a database from a large clinical trial of children with mild to moderate asthma (n = 1041). Measurements of lung function, symptoms, and health care utilization from daily diary cards, serum IgE levels, total eosinophil count, skin test positivity, and airway hyperresponsiveness were included. Data on fractional exhaled nitric oxide and sputum eosinophil cationic protein were included in a subgroup of patients.

RESULTS

In each of the study windows, factor analysis identified 5 factors that explained between 50% and 60% of the common variance. Factors identified included (1) inflammatory markers, (2) symptoms/medication use, (3) asthma exacerbations, and measures of lung function, which subdivided into (4) FEV(1) and forced vital capacity, and (5) bronchodilator response and the FEV(1)/forced vital capacity ratio. Exploratory analyses suggest that fractional exhaled nitric oxide account for the atopy/inflammatory marker factor, and sputum measurements account for a sixth, separate factor.

CONCLUSION

The consistent identification of a 5-factor structure across time and treatment arms suggests that each of these factors provides independent information in the assessment of asthma.

Serial exhaled nitric oxide measurements in the assessment of laboratory animal allergy

BACKGROUND

Laboratory animal allergy (LAA) may cause eosinophilic airway inflammation, for which exhaled nitric oxide (FE(NO)) measurements are sensitive and specific. Our objective was to assess whether serial FE(NO) measurements might detect exposure-related inflammation in laboratory animal workers. METHODS. Fifty laboratory animal workers participated. Measurements of FE(NO) and spirometry were obtained at baseline (Friday) and twice-daily following a weekend with no animal contact.

RESULTS

Eleven of 50 subjects had work-related symptoms, and 2 of 11 had positive serology for LAA. Baseline FE(NO) was high (> 150 ppb) in the two seropositive subjects and increased progressively during the working week in one subject, confirming exposure-driven airway inflammation. In seronegative subjects, mean FE(NO) levels were 19.8 (standard deviation [SD], 20.1) and 21.7 (SD, 20.8) in the symptomatic and nonsymptomatic groups, respectively, with no significant changes in FE(NO) over time.

CONCLUSION

Serial FE(NO) measurements may provide complementary information in the assessment of possible occupational sensitisation. The sensitivity and specificity of this approach to diagnosing occupational asthma requires further evaluation.

The value of sputum 8-isoprostane in detecting oxidative stress in mild asthma

BACKGROUND

Exhaled nitric oxide and induced sputum eosinophils are well established as direct markers of inflammation/oxidative stress in asthma. Recently, it has been proposed that sputum 8-isoprostane concentrations may present a reliable index for measuring oxidative stress in asthmatic patients. We assessed the value of sputum 8-isoprostane in mild asthma in children and adolescents.

METHODS

Patients with newly diagnosed asthma (children, n = 23; adults, n = 14) and age-matched healthy controls (children, n = 13; adults, n = 15) were studied. Lung function was measured by spirometry, sputum was induced by hypertonic saline, and fractional exhaled nitric oxide (FeNO) was measured with standard methods. Cell differential counts were obtained from sputum slides and the concentration of 8-isoprostane was measured with an enzyme immunoassay from sputum supernatants.

RESULTS

High-quality sputum specimens could be obtained from 10 children and 10 adults, and the sputum analyses were conducted only for the representative specimens. Asthmatics had increased FeNO (children 35.5 vs. 11.9 ppb; adults 81.1 vs. 16.6 ppb; p < 0.001) and sputum eosinophils (children 2.4% vs. 1.4%; adults 10.4% vs. 0.2%; p = 0.005) compared to healthy controls. There was a significant correlation between FeNO and eosinophils (R = 0.65; p < 0.0001). Sputum 8-isoprostane was not elevated in asthmatics compared to healthy subjects (children 81.1 vs. 89.9 and adults 76.9 vs. 73.4 pg/mL) and did not correlate with lung function or other measurements of airway inflammation. However, increased 8-isoprostane levels were detected in patients with chronic obstructive pulmonary disease (n = 11, 184.7 pg/mL, used as controls for assays).

CONCLUSIONS

In agreement with earlier studies, FeNo is sensitive in detecting oxidative/nitrosative stress in asthmatic airways. However, our results suggest that 8-isoprostane may not be sensitive in reflecting oxidant burden in mild asthma.

[What methods can we use to measure inflammation in the asthmatic child?]

Pulmonary function tests remain the best method to assess underlying bronchial inflammation, particularly distal airway flow. However, these tests are limited in their ability to differentiate treatment-reversible small airway obstruction from definitive remodeling related to a viral infection. The increased availability of the exhaled fraction of nitric oxide (FeNO) measurement means that this method is accessible and attractive. In spite of a number of studies, mainly in adults, its use in the management of asthma needs more investigation. Threshold values that permit optimum management are poorly defined, and strategies based on variations of FeNO do not result in reduction of the number of exacerbations, although they do permit better control of drug use and better control of inflammation. Sputum eosinophil counts are of interest for the prevention of exacerbations, although while not well validated they may be useful in some asthmatic children. Also, they require an experienced cytology laboratory. Finally, recent data on bronchial biopsies in children with difficult-to-treat asthma will be summarized.