Evaluation of exhaled breath temperature (EBT) as a marker and predictor of asthma exacerbation in children and adolescents.

INTRODUCTION

Noninvasive and easy-to-use tools to monitor airway inflammation in asthma are needed to maintain disease control, particularly in pediatric population. The aim of the study was to evaluate exhaled breath temperature (EBT) in pediatric respiratory clinic setting.

METHODS

We evaluated 37 children and adolescents with asthma (5-17 years; median: 11 years). The patients were followed up in stable condition and during exacerbations (paired observations in n = 19 subjects). We evaluated medication use, EBT, fractional exhaled nitric oxide (FeNO), spirometry and atopic status of patients.

RESULTS

EBT was significantly higher in children with asthma exacerbation {entire group: median [interquartile range (IQR)]: 32.3 [1.1]°C vs. 33.8 [1.7]°C; p < 0.001 and mean ± SD: 33.1 ± 1.0°C vs. 33.6 ± 1.1°C; p = 0.038 for paired observations}. Significant correlation was observed between EBT and FeNO in the entire group (r = 0.22; p = 0.03). No difference was observed in EBT median values in atopic and non-atopic subjects in the entire group (median [IQR]: 32.6 [1.6] vs. 32.7 [2.0]; p = 0.88) and in subgroups. There was no difference in EBT values in patients receiving systemic or inhaled glucocorticosteroids (p = 0.45 and 0.83). There was no significant correlation between EBT and body or room temperature. The only significant predictor of exacerbation in logistic regression model was EBT {aOR = 2.4; 95% [confidence interval (CI)]: 1.4-4.1}. ROC analysis demonstrated applicability of EBT as a marker of asthma exacerbation in children (AUC = 0.748; p < 0.001; cut-off = 33.3°C; sensitivity: 64.3%; specificity: 82.1%).

CONCLUSIONS

We suggest that EBT may serve as marker and predictor of asthma exacerbation in children. EBT follow-up may be useful in asthma monitoring in children and adolescents.