Background: Exhaled breath temperature (EBT) is expected as one of the non-invasive markers of airway inflammation. However, relationship between EBT and asthma management is not fully elucidated. 

Objectives: To investigate associations between EBT and control status in asthma.

Methods: Thirty-one asthmatics (8 mild, 7 moderate, and 16 severe) and 14 healthy subjects were recruited. EBT was measured using by the commercially available handheld device, X-Halo^® (Delmedica, Singapore). FeNO, spirometry, axillary temperature, and asthma control questionnaire (ACT) were also performed.

Results: There was no significant difference in EBT between asthmatics (34.54±0.68°C) and healthy subjects (34.24±0.51°C) (p=0.14). No association was observed between EBT and asthma severity. However, EBT in poor controlled asthmatics (EBT 35.00±0.40°C) was significantly higher than those in well controlled asthmatics (EBT 34.41±0.69°C). When EBT was classified by the upper limit of 95% confidence Interval of healthy subjects (EBT<34.53°C), asthmatics with a history of exacerbation in the previous year had significantly higher EBT compared to those without it (p<0.05).

Conclusion: EBT may provide useful information on predicting not only control status but also future risks of exacerbation in asthma.