Validation of the novel transdermal arterial gasotransmitter sensor (TAGS™) system in measuring transdermal hydrogen sulfide in human subjects

Abstract

A novel non-invasive system has been developed to measure transdermally emitted hydrogen sulfide (H₂S) from the upper and lower limbs of human subjects. The transdermal arterial gasotransmitter sensor (TAGS^™) has previously been shown to detect low levels of H₂S ranging between 1 and 100 ppb considered relevant for physiological measurements (Shekarriz et al. 2020). This study was designed to compare its measurement precision in detecting transdermal H₂S to a commercially available chemiluminescent device, the H₂S-selective Ecotech Serinus 55 TRS^™. Although TAGS^™ does in-situ and real-time sampling, the comparative studies in this paper collected gases emitted from the lower arm of 10 heathy human subjects between the ages of 30 and 60. Three replicate samples of each individual were collected for 30 min in a sealed 10 L Tedlar^® bag to allow readings from the same sample by both devices. Readings from the TAGS^™ system correlated strongly with the values obtained from the Serinus^™ device, both ranging between 0.31 ppb/min and 2.21 ppb/min, with a correlation coefficient of R² = 0.8691, p < 0.0001. These results indicate that TAGS^™ measures transdermal H₂S specifically and accurately. Because vascular endothelial cells are a known source of H₂S, TAGS^™ measurements may provide a non-invasive means of detecting endothelial dysfunction, the underlying cause of peripheral artery disease (PAD) and microvascular disease. TAGS^™ has potential clinical applications such as monitoring skin vascular perfusion in individuals with suspected vascular disease or to monitor progression of wound healing during treatment, which is of particular value in diabetic patients with calcified arteries limiting detection options.

Keywords: Biosensor; Electrochemical; H2S; Medical device; TAGS.

Fig. 1.

Violin plot of Serinus^™ readings and TAGS^™ readings of gas samples collected from 10 different humans analyzed via a paired t-test. No significant difference in mean values of transdermal H₂S readings between the two groups (p = 0.509). Each individual is represented by a different colour.

Fig. 2.

Regression lines for TAGS^™ readings (ppb) and Serinus^™ readings (ppb) of 14 samples. There is strong significant correlation between TAGS^™ readings and Serinus^™ readings (R² = 0.9189, p < 0.0001). Device readings using varying concentrations of standard gas are represented by a red point. The solid red line is the linear regression line representing the goodness of fit between these two variables. The dotted red line represents the 95% prediction bands of the best-fit line testing standard gas.

Fig. 3.

Relationship between TAGS^™ readings (ppb) and Serinus^™ readings (ppb) of 10 human gas samples analyzed via linear regression analysis. Device readings using collected human gas samples are represented by a blue point. The solid red line is the linear regression line comparing the two device readings using calibration gas. The dotted red line represents the 95% prediction bands of the best-fit line testing calibration gas. All human gas samples fit within the 95% prediction bands.