Use of novel tidal breathing monitoring device to detect methacholine challenge test responders

Abstract

Background: Monitoring lung function of asthmatics heavily relies on difficult to perform spirometry, thus passive and seamless monitoring solutions are warranted. However, the possibility to reliably detect clinical changes among asthmatics by monitoring tidal breathing remains unclear.

A preliminary methacholine challenge test (MCT) study was performed to evaluate how tidal breathing parameters measured by a novel wearable device (SenseGuard™) compare to FEV₁ and whether they can differ between MCT responders and non-responders.

Methods: 35 subjects suspected of asthma underwent MCT and were classified as responders or non-responders according to ATS guidelines. During MCT, they underwent tidal breathing measurements and parameters such as RR, inspiratory time (T_in), expiratory time (T_ex), no-flow time between breaths (T_rst), total breath time (T_tot), and the corresponding ratios were calculated in the baseline, methacholine doses and recovery phases.

Results: FEV₁ max. response change between responders (n=18) and non-responders (n=17) was significant (p<0.001), with a reduction of 22% and 3%. Similarly, the change in the novel biomarkers T_ex/T_tot and T_rst/T_tot between the groups was significant (p<0.02), with an increase of 31% and a decrease of 51% for the responders, while statistically insignificant for the non-responders. The remaining parameters did not change for both groups.

Conclusions: Tidal breathing parameters measured by the novel device can reliably detect changes in breathing pattern during MCT. Given the current findings, we hypothesize that this technology might be feasible to monitor clinical changes in asthmatic patients in general. Further studies are warranted.