Slower rise of exhaled breath temperature in chronic obstructive pulmonary disease

In chronic obstructive pulmonary disease (COPD) there is decreased vascularity of the bronchi and inflammation of the airways that may have opposite effects on the regulation of heat loss. Exhaled air temperature increase (Δe°T) was measured in 23 patients with moderate COPD (18 male, mean age±sem 70±1 yrs; forced expiratory volume in one second (FEV 1 ) 45±3%, FEV 1 /forced vital capacity 54±4%) and 16 normal volunteers (64±4 yr) and compared to exhaled nitric oxide (eNO) and inflammatory cells in induced sputum as a marker of airway inflammation. Δe°T was measured during a flow- and pressure-controlled single exhalation with a fast-response thermometer. Δe°T was reduced in patients with COPD (1.86±0.15 Δ°C·s −1 ) compared to normal subjects (4.00±0.26 Δ°C·s −1 ). There was no difference in Δe°T between patients treated with inhaled steroids and those who were steroid naïve. Δe°T was correlated with eNO (r=0.60) but not with sputum neutrophilia. In COPD patients, Δe°T was increased (2.26±0.16 Δ°C·s −1 ) after the inhalation of 200 µg of albuterol, which is a known vasodilator, indicating that Δe°T and bronchial blood flow may be correlated. Exhaled temperature increase is reduced in chronic obstructive pulmonary disease patients and is increased by the inhalation of vasodilators and therefore may be related to changes of bronchial blood flow and tissue remodelling.