Effect of Far Infrared Therapy on Arteriovenous Fistulas Maturation, Survival and Stenosis. A Randomized, Controlled Open-labeled Multicenter Study

Background:

The number of hemodialysis patients in the world are increasing. In order to receive an efficient dialysis, the patient needs a well-functioning and stable vascular access. Presently there is three options: an arteriovenous fistula (AVF), an arteriovenous graft (AVG) and a central venous catheter (CVC). CVCs are associated with an increased risk of stenosis of the central vessels, thrombosis in the AVF, infections and death. AVGs are associated with increased risk of infections, stenosis in the AVG and loss of access. This is why, the AVF is the preferred vascular access. But this vascular access does not come without risks. After the creation of an AVF there is a risk of 50 % for never maturing, which means the AVF cannot be used. Furthermore, the risk of stenosis in the AVF is also high, up to 67 % of the AVFs will have a stenosis, that needs an intervention. During this time the patient needs an alternative vascular access, such as a central venous catheter, which is related to an increased risk of infection, more hospital days and death.

The maturation of the AVF depends on several patient related, but also surgically related factors. Factors such as comorbidity, female sex, length of end stage renal disease, anatomy of the vessel, surveillance after AVF placement and the operations itself have all been shown to affect the AVF maturation. Fistula stenosis emerges from an endothelial dysfunction, inflammation and smooth muscle cell proliferation leading to intimal hyperplasia and in the end stenosis. Factors such as increased blood flow, inflammation, uremia and percutaneous transluminal angioplasty has been shown to affect the stenosis, It is not well understood, which molecular mechanism are responsible for the intimal hyperplasia.

There are few and not well established studies on how to improve the AVF survival and maturation.

Far infrared radiation (FIR) is an electromagnetic radiation (heat therapy), that is given directly on the skin above the AVF. In a few single center studies in Taiwan it has been shown to decrease the risk of stenosis and increase the fistula survival and maturation. However another study is disputing this. The mechanism behind FIR and better fistula survival is not fully understood. The infrared light is supposed to have a thermal effect, which leads to vasodilatation and a non-thermal effect, which influence the endothelial function and vasodilation and thereby it may decrease the inflammation and proliferation in the fistula, primarily through the releasing of several anti-inflammatory and vasodilating factors. This is not well documented.