Exhaled breath temperature increases at COPD exacerbation and correlates with sputum neutrophilia

Introduction: Assessment of exhaled breath temperature (EBT) has been suggested as a novel tool to detect airway inflammation. EBT and the rate of temperature increase are altered in stable states of asthma and COPD compared to healthy controls. In asthma EBT correlates with eosinophil percentage in sputum. However, it is not known if EBT changes at acute exacerbation of COPD and how it relates to airway inflammation, spirometric values and patient9s health status. Methods: Ten patients with previously diagnosed COPD (age 63±11 years) were recruited 24 h within the onset of exacerbation (Anthonisen type I) and after systemic steroid and/or antibiotic treatment at recovery (7.6±1.4 days after). At visits EBT was recorded with a breath thermometer (X-Halo, Delmedica Investments Ltd, Singapore), spirometry was done, patients completed the COPD Assessment Test (CAT) and the first spontaneous sputum in the morning was collected and processed (Yamamoto C et al. Chest 1997). Paired t-test and Spearman correlation were used. Results: EBT at exacerbation was higher compared to that at recovery (34.42±0.73°C vs. 34.03±0.56°C, p=0.03). Sputum neutrophil percentage at exacerbation showed a positive correlation with EBT (r=0.78, p=0.02), and fell after treatment (57±12% vs. 39±18%, p=0.04). EBT at exacerbation was not related to spirometric variables or CAT score. Conclusion: EBT rises at acute exacerbation of COPD and it is associated with increased airway inflammation. Measuring exhaled breath temperature might be useful for monitoring airway inflammation in COPD. The study was supported by Hungarian Respiratory Society grant (to Zsόfia Lazar) and OTKA 68808.