Exhaled breath temperature(EBT) in asthmatic patients: Influence of severity and underlying mechanisms

Abstract

Introduction: Increased vascular permeability leads to loss of heat in the airways and may modulate Exhaled breath temperature ( EBT). Aim: We wanted to determine whether the measurement of EBT in asthmatic patients is influenced by the increased vascular permeability and whether VEGF is implicated in the above process. Furthermore, to assess the impact of asthma severity on EBT values. Methods: 51 asthmatic patients optimally treated for at least 6 months were studied (38women, age 54±12 years old, 26 patients with severe asthma, non-smokers). EBT was measured with X-halo device [DelmedicaInvestments (Singapore)]. All patients underwent, spirometry, sputum induction for the measurement of % inflammatory cells and for the assessment of both VEGF and albumin in sputum supernatant. Albumin was also measured in serum. The airway vascular permeability (AVP) index was calculated as the ratio of albumin concentrations in induced sputum and serum. Results: The median IQR value of EBT[°C] was significantly higher in patients with severe asthma compared to those with mild to moderate one [ 34.34 ( 33.19-34.55) vs 30.7 ,Cl 25.52-33.57), p 1 % pred. Ιn a further stepwise analysis AVP presented the strongest association with EBT. VEGF seemed not to participate in the above process. Conclusion: EBT is increasing in severe asthma but the underlying severity failed to be a predictor of EBT in the multivariate analysis. AVP is implicated in the EBT process irrespective of the presence of VEGF. .