Exhaled Breath Temperature Increases during Mild Exacerbations in Children with Virus-Induced Asthma

Abstract

Background: Exhaled breath temperature (EBT) has been suggested as a non-invasive surrogate marker of airway inflammation in asthma. The aim of the study was to evaluate differences in EBT between periods of controlled disease and during exacerbations in children with virus-induced asthma. Methods: Twenty-nine children (aged 6–14 years) with a history of intermittent, virus-induced asthma were included in this case-control study. Cases presented with a common cold and/or mild exacerbation of asthma, while controls were free of asthmatic or common cold symptoms during the previous 6 weeks. A baseline questionnaire was obtained. Atopy assessment, central temperature and a spirometric measurement were recorded. EBT was measured with a new device (Delmedica, Singapore). A nasal wash (for identification of common respiratory viruses) was obtained. Results: Twenty-four children (12 from each group) completed the study. Groups were homogeneous with respect to baseline characteristics. PCR revealed the presence of a virus in 3 out of 17 controls and 10 out of 12 cases (17.6 and 83.3%, respectively, p = 0.002). The most commonly identified virus was rhinovirus (3/3 controls and 7/10 cases, p = 0.02). EBT values were significantly higher for cases (34.91 ± 0.62°C) compared to controls (34.18 ± 1.1°C, p = 0.032). No important differences were observed in the increase rate of EBT (Δe°T) between groups. Conclusions: Changes in airway inflammation during virus-induced asthma exacerbations are reflected in EBT changes. These preliminary data suggest a possible role of EBT measurements in the assessment of airway inflammation in children with virus-induced asthma.

Exhaled breath temperature in children: reproducibility and influencing factors

“…Consistent with the findings of a previous study [21], our study showed that EBT measurements are highly feasible in children. As previously mentioned by Pifferi et al [22], we also found a learning effect, i.e.…”

“…Other authors, using the single breath technique, found that the rate of EBT increase (De T) [5,9], or the plateau value at the end of expiration (PLET, C) [10,22], distinguished asthmatic subjects from healthy controls. On one hand, with the study of Popov et al [12] and Xepapadaki et al [21], we did not include patients with uncontrolled asthma or virus-induced asthma exacerbations; yet our asthmatic children had lower lung function values and higher FE NO levels than their healthy controls, therefore, indicating atopic airway inflammation. Notwithstanding, without a direct physiological measure (e.g.…”

Exhaled breath temperature and exercise‐induced bronchoconstriction in asthmatic children

“…EBT was measured with an X‐Halo device (Delmedica Investments, Singapore) according to previously validated methods 14, 15. Briefly, the children were requested to inhale freely through the nose and to exhale into the device at a rate and depth typical of their normal tidal breathing rhythm.…”

Exhaled Breath Temperature in Asthmatics and Controls after Eucapnic Voluntary Hyperventilation and a Methacholine Challenge Test

“…Oral temperature displayed the same pattern as EBT after both the provocation tests that we used as well as after exercise, proving that the two temperature measurements are closely related. Although the X-Halo has been validated in previous studies [2,4], one must take into consideration the possibility that since measurements reflect the plateau of the breath temperatures of several expirations registered during a time period of a few minutes, oral temperature in itself may have some effect on the result. This would be in contrast to the single-breath method described in other studies [5,6,7,8].…”

“…It has been shown to relate to disease exacerbations [2,3,4] as well as to vascular [5] and fibrous remodeling [6] of the airways, and to correlate with levels of exhaled nitric oxide (NO) in childhood and adult asthma [7,8]. Sub-epithelial blood vessel density is higher in asthmatic subjects than in healthy controls [9], and the hypothesis is that increased blood flow during airway inflammation would result in heating of the ventilated air to a higher temperature [5].…”