Impact of xylomethazoline-mediated airway vasoconstriction on exhaled breath tempearture measured by a novel method: A pilot study

Abstract

Background: Measurement of exhaled breath temperature (EBT) has been used to evaluate inflammation in the respiratory system. It has been proven that vasodilation in the airways corresponds to higher EBT, but whether vasocinstriction decreases the temperature is not sufficiently studied. Aim: To assess the effect of bronchial vasoconstriction on EBT. Methods: Twelve adults (6 males) were included, half of them smokers, mean age 31.2±5.9. We used a fast responsive thermal sensor (1kHz sampling rate) placed in a mouthpiece with a valve which ensures a closed 18.5ml chamber in front of the subject9s mouth to collect samples of the exhaled air during tidal breathing. From the curve produced we analyzed steady states at different time points and took the mean of the peak values of at least 3 consecutive respiratory cycles. At baseline EBT was measured and then a solution of xylomethazoline (α-adrenergic agent) and normal saline (1.25ml/1.25ml) was inhaled for 2 minutes via an ultrasound nebulizer. The EBT was monitored for 20 min after the inhalation. Heart rate and saturation were also measured with a pulse-oxymeter. Results: Mean baseline EBT for all subjects was 34.67±0.46°C and it decreased in 11 subjects after the inhalation with lowest temperature at different time points. The largest drop in EBT for each subject compared to baseline was between 0.25 and 1.97°C (mean 0.86°C) (p=0.002). Heart rate and saturation did not show any significant change. Conclusion: EBT decreases significantly after inhalation of a vasoconstrictive agent. The response was quite similar in a heterogenous group and shows that EBT is reflecting vascular tone in the airways.