Speaker
Description
The evaluation of vascular access in patients with chronic kidney disease undergoing hemodialysis requires accurate and reliable diagnostic techniques capable of delineating superficial venous anatomy, hemodynamic alterations, and the anatomical characteristics of arteriovenous fistulas (AVFs), while minimizing invasiveness and patient-related risks. In this context, clinical infrared thermography imaging represents a non-invasive functional technique based on the quantitative analysis of cutaneous temperature variations closely related to local blood perfusion.
Thermography detects infrared radiation emitted by tissues at temperatures above absolute zero using high-resolution professional thermal cameras (464 × 348 pixels in the present study, FLIR A500). To obtain clinically meaningful measurements, thermographic assessments were performed after a 30-minute acclimatization period in a temperature-controlled environment (approximately 25°C), allowing stabilization of baseline skin temperature. Under these conditions, thermal maps of the arms and forearms enable the identification of hyperthermic areas associated with mature AVFs and high blood flow rates (>600 ml/min), as well as hypothermic regions suggestive of reduced perfusion or distal ischemia. In this study, thermography was applied both in the preoperative phase and during postoperative follow-up of AVFs.
In the preoperative setting, thermography was integrated with intravenous infusion of cooled saline solution (15°C), administered at 20 ml/min via a needle cannula placed distally to the planned anastomotic site. The aim was to generate a controlled thermal gradient along superficial veins, detectable within approximately 30 seconds after infusion, thereby enhancing visualization of venous pathways and enabling identification of flow discontinuities, stenoses, or collateral circulation, without inducing vascular trauma or phlebitic complications.
Thermography was also employed in the assessment of arterial perfusion through post-occlusive reactive hyperemia (PORH) testing, with results compared to those obtained by pulsed-wave Doppler ultrasound. Based on Doppler-derived resistance indices, 7 subjects were classified as having a normal vascular response and 7 as vasculopathic. The same subjects subsequently underwent thermographic monitoring during the reperfusion phase. In healthy subjects, the reperfusion phase was characterized by a significant increase in skin temperature (ΔT = 3.22 ± 1.18°C), whereas in vasculopathic patients the thermal response was markedly reduced (ΔT = 1.43 ± 0.89°C), in agreement with Doppler findings.
In relation to digital phlebography, currently considered the gold standard for the evaluation of deep and central veins, cold-contrast thermography demonstrates high sensitivity in the early diagnosis of hemodialysis access–induced distal ischemia (HAIDI) and in the identification of superficial venous drainage abnormalities.
In conclusion, clinical thermography represents a complementary diagnostic tool to conventional imaging techniques, providing a functional, dynamic, and repeatable assessment of vascular access. Further prospective studies could contribute to standardizing acquisition and analysis protocols, quantitatively assessing diagnostic accuracy, and defining guidelines for the routine integration of thermography into clinical pathways for vascular access management.
