A novel, microvascular evaluation method and device for early diagnosis of peripheral artery disease and chronic limb-threatening ischemia in individuals with diabetes

OBJECTIVE: A novel transdermal arterial gasotransmitter sensor (TAGS) has been tested as a diagnostic tool for lower limb microvascular disease in individuals with and without diabetes mellitus (DM). METHODS: The TAGS system noninvasively measures hydrogen sulfide (H(2)S) emitted from the skin. Measurements were made on the forearm and lower limbs of individuals from three cohorts, including subjects with DM and chronic limb-threatening ischemia, to evaluate skin microvascular integrity. These measurements were compared with diagnosis of peripheral artery disease (PAD) using the standard approach of the toe brachial index. Other measures of vascular health were made in some subjects including fasting blood glucose, hemoglobin A1c, plasma lipids, blood pressure, estimated glomerular filtration, and body mass index. RESULTS: The leg:arm ratio of H(2)S emissions correlated with risk factors for microvascular disease (ie, high-density lipoprotein levels, estimated glomerular filtration rate, systolic blood pressure, and hemoglobin A1c). The ratios were significantly lower in symptomatic DM subjects being treated for chronic limb-threatening ischemia (n = 8, 0.48 ± 0.21) compared with healthy controls (n = 5, 1.08 ± 0.30; P = .0001) and with asymptomatic DM subjects (n = 4, 0.79 ± 0.08; P = .0086). The asymptomatic DM group ratios were also significantly lower than the healthy controls (P = .0194). Using ratios of leg:arm transdermal H(2)S measurement (17 subjects, 34 ratios), the overall accuracy to identify limbs with severe PAD had an area under the curve of the receiver operating curve of 0.93. CONCLUSIONS: Ratios of transdermal H(2)S measurements are lower in legs with impaired microvascular function, and the decrease in ratio precedes clinically apparent severe microvascular disease and diabetic ulcers. The TAGS instrument is a novel, sensitive tool that may aid in the early detection and monitoring of PAD complications and efforts for limb salvage.