Supplementary Material for: The effect of far infrared treatment on changes in biomarkers in the arteriovenous fistula

Introduction
Far infrared radiation may improve arteriovenous fistula maturation and patency rates in patients on hemodialysis (HD). The mechanism is proposed to involve anti-inflammatory and vasodilatory effects in the arteriovenous fistula. This study examined the impact of far infrared radiation on plasma changes and dialysate excretion of biomarkers of endothelial dysfunction, inflammation, and vasodilation in the arteriovenous fistula during a single HD.

Methods
The study was a randomized controlled single-blinded study in 44 participants on HD with an arteriovenous fistula. Participants were randomized to far infrared radiation or no far infrared radiation (control). Blood samples and dialysate water were drawn before, during and after four hours of HD. The change and elimination of biomarkers of endothelial dysfunction, inflammation and vasodilation was explored in blood and dialysate water, respectively. Changes in plasma levels from start to end of HD and the area under the curve for the biomarker concentration were compared between groups by ANCOVA.

Results
There was no difference in the change of biomarkers of endothelial dysfunction, inflammation, and vasodilation between the two groups after and during four-hours of HD. There was a minimal excretion of the biomarkers in the dialysate water. Regardless of treatment group, four-hours of HD caused a significant decrease in tumor necrosis factor-alpha (-1.30 [-1.70;-1.03] pg/ml , P= <0.001), monocyte chemoattractant protein-1 (-32.50 [-50.50;-8.25] pg/ml, P= <0.001), nitrite, and nitrate (-20.00 [-27.75;-14.00] µmol/L, P= <0.001) as well as asymmetric dimethylarginine(-0.24 [-0.28;-0.18], µmol/L P= <0.001).

Conclusion
Overall, the study is not supportive of a beneficial effect of far infrared radiation on the arteriovenous fistula on biomarkers of endothelial dysfunction, inflammation or vasodilation during one HD treatment.