Validation of the Exhaled Breath Temperature Measure: Reference Values in Healthy Subjects

Background Exhaled breath temperature (EBT) is a new noninvasive method for the study of inflammatory respiratory diseases with a potential to reach clinical practice. However, few studies are available regarding the validation of this method, and they were mainly derived from small, pediatric populations; thus, the range of normal values is not well established. The aim of this study was to measure EBT values in an Italian population of 298 subjects (mean age, 45.2 ± 15.5 years; 143 male subjects; FEV1, 97.2% ± 5.8%; FVC, 98.4% ± 3.9%) selected from 867 adult volunteers to define reference values in healthy subjects and to analyze the influence of individual and external variables on this parameter. Methods EBT was measured with an X-halo PRO device to different ambient temperature ranging from 0°C to 38°C. Results We report reference values of EBT in healthy white subjects who had never smoked. EBT values were strongly influenced by the external temperature and to a lesser extent according to sex. Conclusions In a large population of healthy subjects who never smoked, these data provide reference values for measuring EBT as a basis for future studies. Our results are contribute to the promotion of EBT from “bench” to “bedside.”