Infrared thermography for control of hemodialysis shunts

Hemodialysis through an arteriovenous (AV) fistula remains the most frequent treatment of terminal renal insufficiency until renal transplantation. In case of malfunction of the shunt colour coded duplex sonography or angiography are used for investigation. The authors tried to evaluate the technical feasibility of infrared thermography for control of hemodialysis shunts. 27 consecutive patients who were planned for duplex sonographic control of their AV-shunts had temperature measurements by infrared thermography before dialysis. All investigations were done under standardized ambient conditions with an Infrared Thermo Tracer TH1100. Morphological and functional aspects of AV-fistulas have been compared with their digitized infrared thermograms. The maximal shunt flow velocity (m/sec) correlated best with the highest temperature difference between arms (p<0.001). The shunt-volume proved to be significantly correlated with the mean temperature difference to the contralateral upper extremity (p<0.05). Patients suffering a complete thrombosis of their shunt (n=4) presented statistically lower maximum temperatures on the surface of their shunt regions (33.9±1.0°C) than AV-fistulas without occlusion (36.3±0.6°C), p<0.01. The authors´ data seem promising that infrared thermography might deliver additional fast and non-invasive global information of function of hemodialysis shunts