Exhaled air temperature in asthma: methods and relationship with markers of disease.

BACKGROUND: Exhaled breath temperature has been proposed as a surrogate marker for the evaluation of airway inflammation in asthmatic patients. OBJECTIVE: The aim of the present study was to extend the investigation of exhaled air temperature as a means for the evaluation of airway inflammation using a professionally developed instrument. METHODS: Fifty-seven children, 41 allergic mild asthmatics and 16 healthy controls have been evaluated. They underwent exhaled air temperature and lung function measurement. The asthmatic children also underwent exhaled nitric oxide measurement, and hypertonic saline sputum induction for the evaluation of eosinophil (EOS) percentage. RESULTS: The level of exhaled temperature was significantly higher in asthmatics than in controls, being 30.18+/-0.14 degrees C vs. 27.47+/-0.24 degrees C (P<0.001). In asthmatic children, a positive relationship was observed between exhaled air temperature and both exhaled nitric oxide (r=0.39; P=0.01) and EOS percentage in samples from induced sputum (rho=0.53; P=0.04). CONCLUSION: The data from the present study support the hypotheses that exhaled breath temperature is related to the degree of airway inflammation in asthma.

Reduction in exhaled nitric oxide immediately after methacholine challenge in asthmatic children.

BACKGROUND: The measurement of exhaled nitric oxide (NO) has recently been proposed as a useful technique for the evaluation of airway inflammation in asthma. The purpose of this study was to determine the effect of methacholine bronchial provocation on the levels of exhaled NO in asthmatic children. METHOD: Exhaled NO was measurement immediately before and after methacholine provocation in 51 children with mild to moderate asthma. RESULTS: A significant decrease occurred in the level of exhaled NO (p<0.0001) after methacholine bronchial provocation which was not correlated with the percentage fall in forced expiratory volume in 1 second (FEV(1)). CONCLUSIONS: The methacholine test should not be used immediately before measurement of exhaled NO in children with asthma.

Relationship between exhaled air temperature and exhaled nitric oxide in childhood asthma.

Airway inflammation is a characteristic of asthma. Exhaled nitric oxide (eNO) has been demonstrated to be related to actual levels of airway inflammation in asthmatic patients. The purpose of this study was to investigate whether the temperature of exhaled air is related to eNO levels. Temperature of exhaled air and eNO were measured in 52 asthmatic children with a cross-sectional design. A significant relationship was demonstrated between eNO and temperature of peak and plateau exhaled air temperature. The relationship between both the peak and the plateau values and eNO was more evident when it was corrected for environmental temperature. These results suggest a relationship between exhaled nitric oxide and the temperature of exhaled air in asthmatic patients not treated with systemic steroids.

Mite avoidance can reduce air trapping and airway inflammation in allergic asthmatic children.

BACKGROUND: We investigated the effects of prolonged allergen avoidance in 18 house dust mite-sensitized asthmatic children during a prolonged residential period at a high altitude, allergen-free environment. METHODS: Evaluations of residual volume (RV) and exhaled nitric oxide (eNO) were performed (i) at admission to the residential house in September, (ii) in December after 3 months of stay, (iii) in January after 15 days at home, exposed to allergens, and (iv) in June after 9 months of stay. RESULTS: During the study period RV showed a significant decrease in December (from 117.5 +/- 7.7% to 96.5 +/- 3.2%) (P < 0.02) and a following increase in January (126.2 +/- 17.2%), after allergen re-exposure (P < 0.03). RV decreased again in June at the end of the study period (91.1 +/- 6.0%) (P = 0.001). FEV(1), FEF(25-75) and VC values did not present significant variations. ENO showed a significant decrease in December after 3 months at high altitude (from 21.3 +/- 3.9 p.p.b. to 11.9 +/- 1.7 p.p.b.) (P = 0.03), but no further significant change. No correlation was found between lung volumes and eNO, probably reflecting different aspects of asthma. CONCLUSIONS: Results suggest that RV may be more sensitive than other respiratory function parameters in identifying children with air trapping, being influenced significantly as the inflammatory indices by effective allergen avoidance/exposure regimen.

Exhaled nitric oxide, serum ECP and airway responsiveness in mild asthmatic children.

The purpose of the present study was to assess the possible relationships between exhaled nitric oxide (ENO), a circulating marker of eosinophil activation, serum eosinophil cationic protein (SECP), level of airway responsiveness to methacholine and lung function in asthmatic children, as well as to compare these markers between children with and without inhaled steroid therapy. In a cross-sectional study ENO, SECP and bronchial hyperresponsiveness to methacholine were evaluated in a group of 57 asthmatic children (21 without and 36 with regulator inhaled steroid therapy; aged 6-13 yrs). ENO was significantly lower in steroid treated children (p<0.01). No significant differences between steroid treated and untreated children were observed for the provocative concentration of methacholine causing a 20% fall in forced expiratory volume in one second (FEV1; PC20), SECP and FEV1. In the whole study population significant increase correlations were observed between PC20 and SECP (r=-0.329, p=0.013) and between ENO and FEV1% of predicted (r=-0.348, p<0.01). In the group not receiving inhaled steroids the inverse relationship between PC20 and SECP was more evident (r=-0.581, p<0.001). In the steroid-treated group a significant inverse relationship was observed between ENO and FEV1 (r=-0.426, p=0.0011). The level of exhaled nitric oxide and the relationships between lung function, bronchial reactivity and markers of inflammation are different between steroid-treated and untreated asthmatic children. This has implications for the monitoring of asthma in childhood.

Exhaled nitric oxide is reduced after sputum induction in asthmatic children.

Exhaled nitric oxide (ENO) and eosinophil sputum markers are considered noninvasive markers of airway inflammation in asthma. The aim of this study was to evaluate whether the procedure of sputum induction can affect the level of ENO. We measured ENO before and after sputum induction by inhalation of hypertonic saline solution in 22 asthmatic children and 9 healthy controls. The ENO mean (+/- S. E.M.) value in the group of asthmatic children was reduced from a baseline value of 20.8 (+/- 3.0) ppb to 17.4 (+/- 2.4) ppb after sputum induction (P = 0.0012). In the healthy controls, the mean baseline value of ENO was 9.1 (+/- 2.1) ppb and it was reduced to 4. 8 (+/- 1.1) ppb after induction of sputum (P < 0.01). We suggest that measurements of ENO should be performed after the induction of sputum in asthmatic patients whenever both tests are done in sequence.

Exhaled nitric oxide in asthmatic children exposed to relevant allergens: effect of flunisolide.

Inhaled corticosteroids are capable of reducing the level of exhaled nitric oxide (expiratory nitric oxide fraction (FE,NO)) in asthmatic patients in a dose-dependent fashion. The aim of this study was to evaluate whether or not treatment with an inhaled steroid can prevent changes in FE,NO after the exposure to relevant allergens, following avoidance, in asthmatic children allergic to house dust mite. Thirty-two house dust mite-allergy asthmatic children were randomly allocated to treatment with inhaled flunisolide (500 microg b.i.d) or placebo and evaluated before and 2 weeks after a period of natural exposure to mite antigens. Lung function and FE,NO were evaluated. FE,NO was increased in the placebo-treated group after antigen exposure. Treatment with inhaled flunisolide prevented such increase in FE,NO (p<0.001). No change was observed in lung function parameters. Inhaled flunisolide is effective in preventing the increase in airway inflammation observed in allergic asthmatic children re-exposed to allergens.

Exhaled nitric oxide and sputum eosinophil markers of inflammation in asthmatic children.

Exhaled nitric oxide and eosinophil sputum markers are considered noninvasive ways in which to evaluate airway inflammation in asthma. The aim of this study was to evaluate the relationships between these methods of evaluation in asthmatic children. In a cross-sectional study of 25 mild-moderate asthmatic children (aged 6-13 yrs, 10 patients on inhaled steroids) exhaled NO was measured along with induced sputum by inhalation of hypertonic saline solution. The sputum was processed for eosinophil count and eosinophil cationic protein (ECP) determination. Serum ECP and lung function (forced expiratory volume in one second (FEV1)) were also measured. A significant correlation was observed between exhaled NO and sputum eosinophils (r = 0.438, p = 0.032) as well as between sputum eosinophils and sputum ECP (r = 0.532, p<0.01). No correlation was observed among exhaled NO and serum ECP, sputum ECP, FEV1, respectively. Furthermore no correlation was observed between sputum eosinophil (%) and serum ECP and between sputum eosinophils and FEV1. There was no correlation among the investigated parameters in children treated with inhaled steroids. In conclusion, exhaled NO and sputum eosinophil counts are concordant in evaluating the degree of airway inflammation in patients with mild-to-moderate asthma. However, the association between these two noninvasive markers becomes less in steroid treated patients.

Influence of environmental concentrations of NO on the exhaled NO test.

Measurement of levels of exhaled nitric oxide (NO) has been proposed as a noninvasive method for evaluating the degree of airway inflammation in asthmatic patients. Some concern in the interpretation of results of such measurement may arise from possible interference by high environmental concentrations of NO inhaled by these patients. The aim of this study was to verify whether environmental concentrations of NO in the range from 0 to 150 ppb can influence levels of exhaled NO. We tested two groups of subjects. The first group, consisting of 16 subjects, was tested when environmental levels of NO were from 0 to 3 ppb and from 20 to 60 ppb, and exhaled NO mean ppb (+/- SEM) levels were 9.81 +/- 1.43 and 9.78 +/- 1.47 (p = ns) (mean +/- SEM), respectively. The second group, consisting of 30 subjects, was tested at ambient NO concentrations of 0 to 3 ppm, 80 to 100 ppm, and 120 to 150 ppb, and for 18 of these subjects who underwent testing under all three conditions investigated, the mean levels of exhaled NO were 9.23 +/- 1.51, 7.78 +/- 1.19, and 9.33 +/- 1.55 ppb (p = ns), respectively. The results of this study suggest that significantly different ambient levels of NO have no effect on levels of exhaled NO.