Exhaled Breath Temperature as a Novel Marker of Future Development of COPD: Results of a Follow-Up Study in Smokers

Abstract

Although only less than one-third of smokers develop COPD, early marker(s) of COPD development are lacking. The aim of this research was to assess the ability of an average equilibrium exhaled breath temperature (EBT) in identifying susceptibility to cigarette smoke so as to predict COPD development in smokers at risk. The study was a part of a multicenter prospective cohort study in current smokers (N = 140, both sexes, 40-65 years, ≥20 pack-years) with no prior diagnosis of COPD. Diagnostic workup includes history, physical, quality of life, hematology and highly sensitive CRP, EBT before and after smoking a cigarette, lung function with bronchodilator test, and 6-minute walk test. Patients without a diagnosis of COPD and in GOLD 1 stage at initial assessment were reassessed after 2 years. COPD was additionally diagnosed based on lower level of normal (LLN) lung function criteria. Utility of EBT for disease progression was analyzed using receiver operator curve (ROC) and logistic regression analyses. Change in EBT after smoking a cigarette at initial visit (ΔEBT) was significantly predictive for disease progression (newly diagnosed COPD; newly diagnosed COPD + severity progression) after 2 years (p < 0.05 for both). ΔEBT had an AUC of 0.859 (p = 0.011) with sensitivity of 66.7% and specificity of 98.1% for newly diagnosed COPD using LLN criteria. We conclude that EBT shows potential for predicting the future development of COPD in current smokers. This was best seen using LLN to diagnose COPD, adding further evidence to question the use of GOLD criteria for diagnosing COPD.

Dynamics of exhaled breath temperature after smoking a cigarette and its association with lung function changes predictive of COPD risk in smokers: a cross-sectional study

“…These findings also support our earlier ones in smokers at risk of developing COPD (4), in whom the rise in EBT from baseline to minute 5 after smoking turned out to be a significant predictor of newly developed COPD over two years of follow-up (4).…”

“…The limitations of our study lie in a relatively small sample, cross-sectional design of the study, and the use of spirometry to measure lung function parameters. However, the protocol using EBT AUC showed to be highly reproducible and in line with other research of early changes in COPD, including our own follow-up study (4).…”

“…Airway sensitivity to cigarette smoke is somewhat specific in COPD, as less than 30 % of smokers develop COPD during their lifetime. Our recent cohort research (4) showed that an increase in EBT five minutes after smoking a single cigarette could be moderately predictive of incident COPD in smokers over two years of follow-up. What that study missed to investigate was the dynamics of EBT after a single smoked cigarette and how this dynamics relates to chronic cigarette smoke exposure and lung function, small airway dysfunction in particular, as an early marker of future COPD.…”

“…One of the methods showing potential in that respect is exhaled breath temperature (EBT) measurement. It has recently been introduced as a new, non-invasive marker of inflammation of the respiratory tract in patients with respiratory diseases (asthma, COPD, cystic fibrosis, bronchial carcinoma), as it was consistently and significantly higher than in healthy controls (3,4). As a biomarker of inflammation and vascularity of the airways it can be used alone or in combination with other inflammatory biomarkers like leukocyte and eosinophil counts, exhaled nitric oxide (FeNO), C-reactive protein, and club cell secretory protein (3,4).…”

In-mask temperature and humidity can validate respirator wear-time and indicate lung health status

“…Additionally, Popov and colleagues showed that there was a significant reduction in EBT after treatment with corticosteroid medication in adult asthmatics [8]. EBT has been investigated as a tool for managing asthma symptoms [910] to help diagnose COPD in smokers [11]. There is limited research on differences in exhaled humidity associated with asthma.…”