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PubMed2006

Personal and ambient air pollution is associated with increased exhaled nitric oxide in children with asthma.

BACKGROUND: Research has shown associations between pediatric asthma outcomes and airborne particulate matter (PM). The importance of particle components remains to be determined. METHODS: We followed a panel of 45 schoolchildren with persistent asthma living in Southern California. Subjects were monitored over 10 days with offline fractional exhaled nitric oxide (FeNO), a biomarker of airway inflammation. Personal active sampler exposures included continuous particulate matter < 2.5 microm in aerodynamic diameter (PM2.5), 24-hr PM2.5 elemental and organic carbon (EC, OC), and 24-hr nitrogen dioxide. Ambient exposures included PM2.5, PM2.5 EC and OC, and NO2. Data were analyzed with mixed models controlling for personal temperature, humidity and 10-day period. RESULTS: The strongest positive associations were between FeNO and 2-day average pollutant concentrations. Per interquartile range pollutant increase, these were: for 24 microg/m3 personal PM2.5, 1.1 ppb FeNO [95% confidence interval (CI), 0.1-1.9]; for 0.6 microg/m3 personal EC, 0.7 ppb FeNO (95% CI, 0.3-1.1); for 17 ppb personal NO2, 1.6 ppb FeNO (95% CI, 0.4-2.8). Larger associations were found for ambient EC and smaller associations for ambient NO2. Ambient PM2.5 and personal and ambient OC were significant only in subjects taking inhaled corticosteroids (ICS) alone. Subjects taking both ICS and antileukotrienes showed no significant associations. Distributed lag models showed personal PM2.5 in the preceding 5 hr was associated with FeNO. In two-pollutant models, the most robust associations were for personal and ambient EC and NO2, and for personal but not ambient PM2.5. CONCLUSION: PM associations with airway inflammation in asthmatics may be missed using ambient particle mass, which may not sufficiently represent causal pollutant components from fossil fuel combustion.

Adolescent↗
PubMed2003

Airway responsiveness to adenosine 5'-monophosphate and exhaled nitric oxide measurements: predictive value as markers for reducing the dose of inhaled corticosteroids in asthmatic subjects.

OBJECTIVES: To investigate the utility of the determination of airway responsiveness to inhaled adenosine 5'-monophosphate (AMP) and exhaled nitric oxide (ENO) levels as markers for safely reducing the dose of inhaled corticosteroids (ICS) in patients with asthma well controlled with a moderately high ICS dose. METHODS: A total of 37 patients with asthma well controlled for at least 3 months by treatment with a moderately high ICS dose (beclomethasone dipropionate, 500 to 1,000 microg or equivalent daily) were included in the study. Patients were treated for a 2-week run-in (baseline) period with their usual dose of ICS. For the next 12 weeks, patients were treated with ICS at half the previous dose, maintaining the same inhalation device. At the end of the baseline period and after 2 weeks, 8 weeks, and 12 weeks of treatment with a reduced dose of ICS, measurements were made in the following order: ENO, spirometry, and AMP challenge. Furthermore, patients completed a diary twice daily recording peak expiratory flow, daytime and nighttime symptoms, and use of rescue albuterol. RESULTS: Ten patients had an asthma exacerbation. Using a Kaplan-Meier survival analysis, the significant predictors of a failure of ICS reduction were having both bronchoconstriction in response to AMP and ENO levels > or = 15 parts per billion (ppb) at baseline (p = 0.006), as well as having both bronchoconstriction in response to AMP and ENO levels > or = 20 ppb at baseline (p = 0.033). Having a decrease in the provocative concentration of AMP causing a 20% fall in FEV(1) of at least one doubling concentration 2 weeks after the dose of ICS was halved was a borderline significant predictor for failure of ICS reduction (p = 0.062). CONCLUSION: These observations suggest that in asthmatic patients well controlled with ICS, the determination of AMP responsiveness and ENO levels may be useful to identifying those subjects whose condition will or will not deteriorate when the dose of ICS is reduced.

Adenosine Monophosphate↗
PubMed2004

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

BACKGROUND: Raised exhaled nitric oxide (Feno) levels have been associated with asthma. However, we have found that in children, Feno was increased in atopic children with increased airway responsiveness (AR), and this was independent of a diagnosis of asthma. STUDY OBJECTIVES: The current study was designed to test the hypothesis that in adults there is no association between Feno and asthma after controlling for atopy and AR. MEASUREMENTS: One hundred fifteen adults (77 women; mean age, 41 years) underwent an assessment that included Feno measurements, spirometry, skin-prick testing, blood eosinophil count, and inhaled histamine challenge (results are expressed as a dose-response slope [DRS]). RESULTS: When only atopic individuals were considered (n = 73), Feno was positively associated with the DRS (p = 0.003), male gender (0.02), and negatively associated with current smoking (p = 0.09). Only male gender (p = 0.03) was associated with Feno among nonatopic individuals (n = 36). In multivariate analysis, there was no association between Feno and current asthma, current wheeze, or asthma ever. CONCLUSIONS: We conclude that in adult subjects, elevated Feno measurements are associated with a phenotype characterized by atopy and increased AR regardless of the presence of asthma or asthma-like symptoms.

Adult↗
PubMed2005

Exhaled nitric oxide predicts exercise-induced bronchoconstriction in asthmatic school children.

BACKGROUND: Exercise-induced bronchoconstriction (EIB) is of particular importance in children with asthma. It is an important measure of asthma control and should be monitored by exercise testing. However, exercise testing puts a large demand on health-care resources and is therefore not widely used in routine monitoring of pediatric asthma control. The fractional concentration of exhaled nitric oxide (FeNO) also reflects uncontrolled asthma. We hypothesized that FeNO may be used for prescreening of asthmatic children to exclude those with good asthma control unlikely to have EIB, thereby reducing the need for exercise testing. OBJECTIVE: The aim of this study was to estimate the value of FeNO as a predictor of EIB in asthmatic children. METHODS: Stable outpatient asthmatic school children performed standard exercise challenge tests and measurement of FeNO. RESULTS: FeNO and response to a standardized submaximal exercise test on the treadmill were measured in 111 school children with asthma. EIB could be excluded with a probability of 90% in asthmatic children with FeNO levels < 20 parts per billion (ppb) without current inhaled corticosteroid treatment, and < 12 ppb in children with current inhaled corticosteroid treatment. CONCLUSION: Measurement of FeNO is a simple, and time- and resource-efficient tool that may be used to screen for EIB testing and therefore optimizes the resources for exercise testing in pediatric asthma monitoring.

Adolescent↗
PubMed2006

Normative data for pH of exhaled breath condensate.

INTRODUCTION: Measurement of pH is one of the simplest and most technically validated biomarkers studied in exhaled breath condensate (EBC). The pH of EBC has been found to be lower than controls in many respiratory disorders. Published data from normal control subjects have been reasonably consistent, but the data sets are not large. This study was undertaken to establish normative EBC pH reference values. PARTICIPANTS: Four hundred four healthy subjects of all ages were enrolled. INTERVENTIONS: Each participant provided a single EBC sample using a disposable collector at modest temperature so that EBC was collected as a liquid. MEASUREMENTS AND RESULTS: Samples of EBC were bubbled with argon gas to standardize for carbon dioxide, and pH was recorded with a calibrated and validated glass microelectrode on stabilization. The median EBC pH was 8.0 with interquartile (25 to 75%) range of 7.8 to 8.1. There were no differences based on age, sex, or race. The distribution is skewed, with 6.4% of EBC samples having a pH range < 7.4. CONCLUSIONS: An extensive normal data set now exists that reveals EBC pH is maintained in a modestly alkaline and tight range in subjects who consider themselves healthy.

Adolescent↗
PubMed2006

Height, age, and atopy are associated with fraction of exhaled nitric oxide in a large adult general population sample.

STUDY OBJECTIVES: The fraction of exhaled nitric oxide (Feno) is elevated in subjects with asthma and atopy, and it has been proposed to be a noninvasive marker of airway inflammation. In addition to asthma and atopy, there is limited information about the determinants of Feno in a general population. DESIGN: Cross-sectional. SETTING: A random adult general population sample. PARTICIPANTS: A total of 2,200 subjects, 1,111 women and 1,089 men, aged 25 to 75 years. INTERVENTIONS: The subjects were examined with regard to Feno, pulmonary function, anthropometric variables, and blood samples for Ig E, and completed a respiratory questionnaire. The associations between different determinants and Feno were analyzed with multiple linear regression models. RESULTS: The median value of Feno was 16.0 parts per billion (ppb), ranging from 2.4 to 199 ppb. Height, age, atopy, reporting of asthma symptoms in the last month, and reported use of inhaled steroids were positively associated with Feno. Current smokers had lower values of Feno. Gender was not associated with Feno. CONCLUSIONS: In this random adult population sample, height, but not gender, was associated with Feno. Furthermore, asthma symptoms in the last month, reported use of inhaled steroids, and atopy were positively and independently associated with Feno, while there was a negative association with smoking.

Administration, Inhalation↗
PubMedDate not supplied

Exhaled nitric oxide levels in military recruits with new onset asthma.

Approximately 800 United States Air Force basic military trainees (BMTs) are diagnosed with asthma, annually, resulting in separation from the military. With training costs of approximately 10,000 dollars/person, around 8 million dollarsis lost per year. Improved methods in diagnosing asthma would be beneficial. The aim of this study was to determine the fraction of exhaled nitric oxide (FENO), a marker of airway inflammation, in a military recruit population referred for an asthma evaluation. In BMTs referred for respiratory complaints during basic training, FENO levels were determined before an asthma evaluation consisting of a history, physical, baseline spirometry, and histamine bronchoprovocation. Of 172 BMTs who had symptoms suggestive of asthma and underwent histamine bronchoprovocation, 80% were diagnosed with asthma. FENO levels were significantly higher in asthmatic patients than nonasthmatic patients (mean, 30 parts per billion [ppb] versus 19 ppb, p < 0.001; median, 21 ppb versus 17 ppb, p < 0.02). Various FENO cutoff points provided a range of sensitivity and specificity for the diagnosis of asthma. However, an optimal FENO cutoff level for asthma was not obtained. An FENO value of 10.5 ppb provided a sensitivity of 86% for the diagnosis of asthma, but specificity was only 21%. In contrast, an FENO value of 46 ppb provided 100% specificity but only 17% sensitivity. FENO levels were significantly elevated in BMTs diagnosed with asthma but the lack of an optimal cutoff level limits the test as a diagnostic tool for asthma. Additional studies are necessary to determine the value of FENO for asthma screening in a military population.

Adolescent↗
PubMed2004

Fractal analysis of tracheal sounds during maximal forced exhalation.

BACKGROUND: Fractal structures or processes, many of which are found in nature, are marked by the presence of a formal pattern that repeats itself even as the scale changes, a property termed 'self-similarity'. The bronchial tree is structurally a fractal system and inspiration is a fractal process. Our objective was to show that the dynamic process of emptying air from the bronchi as measured by tracheal sounds should also behave fractally over the period of time during which exhalation takes place. MATERIAL/METHODS: Twenty non-smoking patients (9 males and 11 females) aged 53.6+/-16.3 years with persistent but clinically stable moderate to severe asthma and a control group of 11 healthy non-smoking subjects (6 males and 5 females) aged 46.0+/-12.5 years were enrolled. Respiratory sounds were registered using a microphone held by an elastic band directly against the patient's skin at the level of the cricoid cartilage. Analysis was done on the average of three forced expirations made after a deep inspiration. The Hurst's coefficient was computed by Hurst's rescaled range analysis (H) and by analysis of the variance-time relationship of the aggregated process (H_v). RESULTS: Values of H and H_v were around 0.75, indicating that the sound signals were fractal over time. The responses of controls and patients to bronchodilator administration of 1 mg terbutaline were similar (p>0.05). Mean intra-subject variation coefficients were less than 15%. CONCLUSIONS: This analysis of tracheal sound during forced expiratory maneuvers confirms the dynamic fractal behavior of the respiratory system.

Adult↗
PubMedDate not supplied

Hyposensitization therapy reduced exhaled nitric oxide in asthmatic children with corticosteroid dependency.

Measurement of exhaled nitric oxide (FeNO) is a simple and noninvasive method for assessment of airway inflammation severity in asthmatic patients. The aim of this study was to investigate whether hyposensitization with extracts of Dermatophagoides pteronyssinus (Der p) and Dermatophagoides farinae (Der f) could decrease airway inflammation as determined by FeNO levels. Ten asthmatic children with corticosteroid dependency were recruited for the study. Eight subjects completed a ten months mite hyposensitization regimen. FeNO concentrations, asthma symptom scores and peak expiratory flow rates (PEFR) were measured monthly before and after treatment. FeNO levels from asthmatic patients were found to be higher before treatment (65.34+/-31.63 ppb). FeNO levels fell significantly after four months' treatment (39.89+/-21.13 ppb; p<0.05). PEFR increased significantly five months after hyposensitization treatment (214.38+/-49.38 vs 251.25+/-28.00; p<0.05). Asthma symptom scores decreased 5 months after hyposensitization treatment (6.84+/-1.22 vs 5.80+/-0.67, p<0.05). Hyposensitization with extracts of Der p and Der f appears to improve clinical symptoms and reduce airway inflammation as determined by FeNO concentrations in children with mite allergy asthma.

Adolescent↗
PubMed2004

Exhaled nitric oxide in bronchiectasis: the effects of inhaled corticosteroid therapy.

SETTING: While exhaled nitric oxide (eNO) levels are reduced by inhaled corticosteroid therapy in asthma, such treatment effect is unclear in bronchiectasis. DESIGN: Stable non-smoking bronchiectasis patients were randomised to receive either fluticasone (1 mg/daily) or identical placebo via the Accuhaler device. RESULTS: Sixty non-smoking patients (38 women; mean age 56.4 +/- 12.7 years) were recruited. Of these, half received inhaled fluticasone and half placebo therapy. eNO was measured using a chemiluminescence analyser at 0, 4, 12, 24, 36 and 52 weeks. There was no significant difference in eNO levels between fluticasone and placebo patients over the study period. There was no correlation between baseline eNO with age, FEV1, FVC, 24 h sputum volume or number of bronchiectatic segments. Patients with Pseudomonas aeruginosa (PA) infection, but not their counterparts, displayed a correlation between 0- and 52-week eNO levels. PA infection was associated with significantly lower eNO levels among the patients. CONCLUSIONS: Inhaled fluticasone therapy, despite being an effective anti-inflammatory agent, has no significant effect on eNO production, either at individual time points or over the entire 52-week profile, in bronchiectasis. It appears that eNO might not reflect the extent of airway inflammation in bronchiectasis.

Administration, Inhalation↗
PubMed2005

[Comparison of oxidative stress markers in exhaled breath condensate and in serum of patients with tuberculosis and sarcoidosis].

UNLABELLED: Tuberculosis and sarcoidosis represent the granulomatous diseases. The aim of the study was to compare the markers of oxidative stress: in exhaled breath condensate (EBC) and in serum of patients with tuberculosis and sarcoidosis. MATERIAL AND METHODS: 19 patients with active lung tuberculosis and 15 patients with sarcoidosis were enrolled into the study. As a control served 15 healthy subjects. Hydrogen peroxide (H2O2) was measured in EBC and the ends products of lipid peroxidation (TBARs) were assessed in serum. RESULTS: The concentrations of H202 and TBARs (1022.96+/-186.02 nM and 4.22+/-0. 80 microM, respectively) were significantly higher in patients with tuberculosis as compared with the controls (398.15+/-37.10 nM and 0.48+/-0.17 microM, respectively). The patients with sarcoidosis revealed only the significantly elevated levels of hydrogen peroxide (963.30+/-105.77 nM) in breath condensate. CONCLUSIONS: It was found that local and systemic oxidative stress were present in patients with tuberculosis, while in those with sarcoidosis existed only the local reaction.

Adult↗
PubMed2005

[Diagnostics of occupational asthma: measurements of exhaled nitric oxide].

Nitric oxide (NO) is an endogenous, soluble gas whose highly reactive molecules are involved in many biological and pathophysiological organic processes. It is generated from arginine through the action of the enzyme nitric oxide synthase (NOS). Over the recent years, accurate and non-invasive diagnostic methods have been searched for illustrating the allergic airway inflammation. Lately, great hopes have been associated with the use of measurements of exhaled nitric oxide (FENO) in the estimation of bronchial inflammation in asthmatic subjects. This method is non-invasive and can be frequently repeated. Furthermore, positive correlation between FENO and blood eosinophilia and induced sputum in atopic children and asthmatic adults has been observed. A significant increase in FENO after specific challenge test has also been shown. Therefore, determination of this parameter can be an additional source of information useful in the interpretation of occupational challenge tests in cases with boderline functional changes.

Adult↗
PubMedDate not supplied

Changes in exhaled nitric oxide levels with immunotherapy.

The mechanisms by which immunotherapy (IT) modulates allergic airway response are not entirely clear. Exhaled nitric oxide (eNO) is a sensitive marker of airway inflammation in allergic respiratory disorders. We hypothesize that eNO may serve as a barometer of the immunomodulatory changes occurring during IT. We aimed to characterize the pattern of eNO levels in children undergoing traditional IT (TradIT) and rush IT (RushIT). Off-line measurements of eNO were obtained in children electing to undergo RushIT or TradIT at a University-based Allergy/Asthma Clinic. The eNO was measured before IT (pre-IT, week 0) was initiated, and at 2, 4, 6, 8, and 12 weeks after starting IT. Nine children received TradIT and 10 children received RushIT. Pre-IT eNO in the RushIT group averaged 12.6 parts per billion (ppb). This was followed by a rise to 17.7 ppb at week 2. The elevated eNO levels persisted till week 8, and then dramatically dropped below the pre-IT values to 8.9 ppb at week 12 (p = 0.038). Similar changes in eNO were not seen in the TradIT group. The difference in eNO levels between the two groups was most marked at 4 weeks (p = 0.014). Initiation of IT produces significant immunomodulatory changes such as a rise in eNO levels. Temporally, the changes appear to be accelerated in the RushIT group compared with the TradIT group, with return to baseline as maintenance IT levels are achieved.

Adolescent↗
PubMed2006

[The importance of exhaled breath condensate analysis in diagnosing a lung disease].

Exhaled breath condensate (EBC) contains aerosolised airway lining fluid and volatile compounds that provide non-invasive insight in biochemical and inflammatory activities in the lung. The interest in EBC has grown rapidly since this easily sampled fluid showed measurable properties that clearly indicate a disease. EBC assays provide evidence of redox deviation, acid-base status, and of the degree and type of inflammation in acute and chronic asthma, chronic obstructive pulmonary disease, cystic fibrosis, adult respiratory distress syndrome, and other lung diseases. Because of uncertain and variable degrees of dilution, EBC does not provide precise assessment of individual solute concentrations within native airway lining fluid. However, it can provide information when concentrations differ substantially between health and disease. Because, EBC assays are approachable and easy to perform, they will become integral components of future clinical studies, and after standardisation is accomplished, they might be used to diagnose and monitor therapy in clinical practice.

Breath Tests↗
PubMed2006

Comparison of exhaled nitric oxide measurement with conventional tests in steroid-naive asthma patients.

BACKGROUND: Nitric oxide (NO) is a molecule with potent biological activity that plays an important role in the physiology of the respiratory system. Increased expression of inducible nitric oxide synthase (iNOS) and elevated fractional concentration of exhaled nitric oxide (F(ENO)) are seen in asthmatic patients. Measurement of F(ENO) has become increasingly recognized for use in the evaluation of bronchial inflammation during monitoring of antiinflammatory treatment. OBJECTIVES: The aim of this study was to evaluate F(ENO) in a group of steroid-naive asthmatics and assess the relationship of this parameter with the results of other tests used in the diagnosis of asthma and monitoring of antiinflammatory treatment in asthmatic patients. METHODS: The study was conducted in a group of 101 steroid-naive asthmatics (56 allergic and 45 nonallergic) and 39 healthy volunteers. All patients underwent measurement of F(ENO), skin prick tests with common inhaled allergens, analysis of serum eosinophil cationic protein (ECP) and blood eosinophilia, and flow-volume spirometry. When the forced expiratory volume in the first second (FEV1) was less than 80% of predicted, reversibility of airway obstruction with a beta2-agonist was assessed. A nonspecific bronchial provocation test with histamine was carried out in asthmatic patients with a baseline FEV1 of more than 70% of predicted. RESULTS: Compared to the healthy volunteers, F(ENO) was elevated in both groups of asthmatics. F(ENO) in the allergic asthma group was higher than in the group of nonallergic asthmatics. In allergic and nonallergic asthmatics, F(ENO) was significantly correlated with bronchial hyperresponsiveness to histamine, reversibility of airway obstruction, serum ECP levels, and blood eosinophilia. F(ENO) did not correlate with baseline FEV, in either group of asthmatics. In 31% of nonallergic and 9% of allergic patients, F(ENO) was less than 20 parts per billion. CONCLUSIONS: We suggest that measurement of F(ENO) could be clinically useful in steroid-naive asthmatics and should be more widely used in clinical practice. Measurement of F(ENO) is a noninvasive, simple, and reproducible procedure, the results of which correlate with other routinely used methods in the diagnosis of asthma. However, it is worth noting that some patients, especially those with nonallergic asthma, do not display elevated F(ENO).

Adult↗
PubMed2006

Exhaled-breath condensate pH can be safely and continuously monitored in mechanically ventilated patients.

BACKGROUND: Airway inflammation in acute and chronic respiratory diseases is characterized in part by abnormal pH in airway-lining fluid. The pH of exhaled-breath condensate (EBC) is low (acidic) in various pulmonary inflammatory diseases, including asthma, chronic obstructive pulmonary disease, cystic fibrosis, pneumonia, and acute respiratory distress syndrome. Because the time course of pH changes in the airway is not yet clear, we aimed to develop a method for frequent and intensive EBC pH data collection in mechanically ventilated patients. METHODS: We examined the collection, gas-standardizing (CO2 removal), and continuous monitoring of pH of EBC from the expiratory port of a Servo-i ventilator with mechanically ventilated patients. We developed a condensing device that attaches to the exhaust port and is chilled by an electric cooling system. We built a 2-chamber gas-standardization and pH-measuring device that attaches to the condensing system and records pH every 6 s. After safety testing, we enrolled mechanically ventilated patients (with diverse reasons for requiring ventilatory support) for up to 96 h of continuous EBC pH condensimetry. RESULTS: The pressure, volume, and flow of the ventilator attached to a test lung were unchanged by application of the condensimeter, at various flows (2-120 L/min) and ventilator settings. We monitored 19 pediatric patients for 6-96 h. The pH of the accumulated EBC in the storage container correlated with the geometric mean of all the pH data points from the condensimeter during the recording period (r2 = -0.95, p < 0.001), which internally validated that the condensimetry system provides accurate, well gas-standardized readings for up to 96 h. The EBC pH values were similar to published reports of single samples. The EBC pH became more acidic during clinical deterioration and normalized with recovery. CONCLUSION: Continuous monitoring of EBC pH from the ventilator exhaust port is safely achievable and reliably provides data that may become useful in monitoring critically ill patients.

Adolescent↗
PubMed2006

The effect of fiberoptic bronchoscopy on exhaled nitric oxide.

Nitric oxide has been extensively studied as a noninvasive marker of airway inflammation. Assuming that bronchoscopy can produce not only systemic but also local inflammatory response, we hypothesized that bronchofiberoscopy can be responsible for an increase in nitric oxide synthesis with resulting increase in fractional concentration of exhaled nitric oxide (FE(NO)). Fifty five subjects (F/M-23/32; mean age 53.9 +/-17.3 yr) undergoing diagnostic bronchoscopy participated in the study. The indications for bronchoscopy were as follows: interstitial lung diseases (n=13; 23.6%), lung cancer (n=11; 20.0%), hemoptysis (n=10; 18.2%), differential diagnosis of asthma/dyspnea (n=9; 16.4%), pulmonary infections (n=7; 12.7%), and others (n=5; 9.1%). During bronchoscopy bronchial washing (n=18), bronchoalveolar lavage (BAL) (n=26), and bronchial biopsies (n=24) were performed. FE(NO) was analyzed on-line with chemiluminescence analyzer (NIOX, Aerocrine, Sweden) according to the ATS guidelines, before and at 1, 2, 3 and 24 h after bronchoscopy. The mean FE(NO) before bronchoscopy was 21.0 +/-3.31(SE) ppb, it decreased to 14.8 +/-2.10 ppb 1 h after bronchoscopy, reached a nadir at 2 h (14.4 +/-2.28 ppb; P<0.05), and was not different from baseline 24 h after bronchoscopy (22.8 +/-2.90 ppb). There were no differences in the FE(NO) profile in BAL patients compared with those in whom only the bronchial washing was performed. We conclude that bronchoscopy leads to a decrease in FE(NO). The underlying mechanisms are at present unclear.

Biopsy↗
PubMed1997

Comparison of exhaled nitric oxide, serum eosinophilic cationic protein, and soluble interleukin-2 receptor in exacerbations of pediatric asthma.

The hypotheses tested in this study were that during acute asthma exacerbations (1) exhaled nitric oxide concentrations [eNO] are a more sensitive, noninvasive indicator of asthma disease activity than serum markers of inflammation such as eosinophil cationic protein (ECP) or soluble interleukin 2 receptor (sIL2R), and (2) elevated [eNO] are reduced after treatment with glucocorticoids (GC). Peak eNO levels were measured by chemiluminescence during slow expiration. Seven asthmatic subjects (mean age 11 yrs; mean morning FEV1 65% predicted) receiving inhaled GC, and with no radiographic evidence of acute sinusitis, were studied before and after a course of oral GC. Measurements of [eNO], ECP and sIL2R levels, and FEV1% were obtained before and after a course of GC. Six atopic nonasthmatic subjects (mean age 12 years; mean FEV1 94% predicted) and seven normal subjects (mean age 13 years; mean FEV1 100% predicted) were studied. The mean peak [eNO] level (parts per billion: ppb) for the asthma subjects before treatment (52 +/- 5 ppb SEM) was greater than the value for both nonasthmatic atopic and normal subjects (16 +/- 2 ppb and 14 +/- 2 ppb SEM, respectively; P < 0.0001). There was no significant difference in ECP or sIL2R values between asthmatic subjects and either atopic or normal subjects (P > 0.05). Baseline pre-GC treatment ECP levels in the asthmatic subjects were significantly higher (P < 0.002) than post-GC treatment values. The mean peak [eNO] level in the asthmatic subjects declined after oral GC treatment to 14 +/- 1 ppb (P < 0.0002) and was less than 2 ppb different from either control group (P > 0.75). We conclude that [eNO] is a more sensitive marker of asthma disease activity than ECP and sIL2R levels. In addition, [eNO] appears to be a more useful indicator of the beneficial response to GC therapy than these other measurements in pediatric asthma.

Acute Disease↗