The correlation between transcutaneous oxygen pressure (TcPO2) and forward-looking infrared (FLIR) thermography in the evaluation of lower extremity perfusion according to angiosome

Abstract

The increased peripheral arterial disease (PAD) incidence associated with aging and increased incidence of cardiovascular conditions underscores the significance of assessing lower limb perfusion. This study aims to report on the correlation and utility of two novel non-invasive instruments: transcutaneous oxygen pressure (TcPO2) and forward-looking infrared (FLIR) thermography. A total of 68 patients diagnosed with diabetic foot ulcer and PAD who underwent vascular studies at a single institution between March 2022 and March 2023 were included. Cases with revascularization indications were treated by a cardiologist. Following the procedure, ambient TcPO2 and FLIR thermography were recorded on postoperative days 1, 7, 14, 21 and 28. In impaired limbs, TcPO2 was 12.3 ± 2 mmHg and FLIR thermography was 28.7 ± 0.9°C. TcPO2 (p = 0.002), FLIR thermography (p = 0.015) and ankle–brachial index (p = 0.047) values significantly reduced with greater vascular obstruction severity. Revascularization (n = 39) significantly improved TcPO2 (12.5 ± 1.7 to 19.1 ± 2.2 mmHg, p = 0.011) and FLIR (28.8 ± 1.8 to 32.6 ± 1.6°C; p = 0.018), especially in severe impaired angiosomes. TcPO2 significantly increased immediately post-procedure, then gradually, whereas the FLIR thermography values plateaued from day 1 to 28 post-procedure. In conclusion, FLIR thermography is a viable non-invasive tool for evaluating lower limb perfusion based on angiosomes, comparable with TcPO2.