Infrared Pedal Temperature and Non-Invasive Vascular Tests in Peripheral Artery Disease: Pilot Study

Ankle/toe-brachial indexes (ABI/TBI) are the gold standard for assessing distal arterial flow but require in-person testing. This pilot study evaluated infrared thermometry as a non-invasive screening tool by assessing its correlation with TBI in peripheral arterial disease (PAD) patients following revascularization.

PAD patients undergoing revascularization were enrolled from January 2024 to November 2024. Foot temperature was measured using the Exergen DermaTemp DT-2000-BT FootScanner at six anatomical locations. Subjects were categorized into wound and non-wound groups. Pearson and Spearman correlations assessed TBI-temperature relationships; Mann-Whitney U test compared groups.

Among 37 patients, 37.8% had foot wounds. Significant negative correlations were observed between TBI and temperature at the 1st metatarsal (R = -0.39, P = 0.035) and midfoot (R = -0.44, P = 0.018). The wound group had lower ABIs (0.57 versus 0.81, P < 0.001), lower toe pressures (42.5 versus 54.0 mmHg, P < 0.0001), and higher temperatures across all foot regions (P < 0.0001). In the wound group, higher TBI correlated with temperatures within the expected physiological range at the hallux (R = -0.67, P = 0.017), 1st metatarsal (R = -0.67, P = 0.018), and 3rd metatarsal (R = -0.62, P = 0.033). No significant correlations were observed in the non-wound group.

Infrared thermometry demonstrated significant negative correlations between foot temperature and TBI. In patients with foot wounds, adequate perfusion was associated with efficient regulation of the inflammatory response, resulting in temperatures within the expected physiological range. In contrast, compromised perfusion was associated with impaired heat dissipation and persistent inflammation, leading to elevated local temperatures. These findings support infrared thermometry as a complementary, non-invasive monitoring tool for PAD patients and warrant validation in larger studies.