Tracking tidal volume non-invasively in volunteers using a tightly controlled temperature-based device: a proof of concept paper.

Introduction There is a paucity of noninvasive respiratory monitors for patients outside of critical care settings. The Linshom respiratory monitoring device is a novel temperature-based respiratory monitor that measures the respiratory rate as accurately as capnography. Objectives Determine whether the amplitude of the Linshom temperature profile was an accurate, surrogate and qualitative metric of the tidal volume (V-T) that tracks V-T in healthy volunteers. Methods Forty volunteers breathed room air spontaneously through a tight-fitting continuous positive airway pressure mask with a Linshom device mounted in the mask. V-T was measured contemporaneously using a standalone Maquet Servo-i ICU ventilator. The amplitudes of the Linshom temperature profiles were paired with the contemporaneous V-T measurements using least squares linear regression analysis and the coefficient of variation (R-2) was determined. Results Forty volunteers completed the study. The data from 30 of the volunteers were analysed and are presented; data from 10 volunteers were not included due to protocol violations and/or technical issues unrelated to Linshom. The fluctuations in the amplitude of the Linshom temperature profiles mapped closely with the measured V-T using least squares linear regression analyses yielding a mean R-2 (95% CI) value of 0.87 (0.84-0.90). Conclusion These results support the notion that the Linshom temperature profile is an accurate and reliable surrogate that tracks changes in V-T in healthy volunteers. Further studies are warranted in patients in clinical settings to establish the effectiveness of this monitor.