Hemodialysis vascular access stenosis remains a frequent complication. However; early detection is challenging and costly. The aim of this in-vitro study was to assess the value of a new detection method based on pressure profile analysis at the hemodialysis needle.

A silicon model of a radio-cephalic arteriovenous fistula was built (4mm artery connected by an end-to-side anastomosis with a 7mm vein). A water-glycerine mixture was used as blood mimicking fluid. Pressure profiles were measured at the arterial hemodialysis needle (4cm downstream the anastomosis) and in the feeding artery 20cm upstream the anastomosis. Stenoses (50% diameter reduction) were created 10cm upstream the anastomosis (proximal artery (PA)) and 3.5cm and 8cm downstream the arterial needle (distal vein (DV) and proximal vein (PV) respectively). The pulse pressure (maximum minus minimum) at the needle was divided by the pulse pressure at the feeding artery to obtain a dimensionless ratio, %PP. Experiments were conducted at different blood flow (500 to 1200 ml/min) and heart rates (60 to 90 beats/minute) to test this new index over a wide range of hemodynamic conditions.

In the control model (no stenosis), %PP was 20.26±4.55%. PA stenosis significantly decreased %PP to 7.69±2.08% (P<0.001), while presence of stenosis in the distal (36.20±2.12%) and proximal (32.38±2.17%) vein lead to significantly higher values of %PP (P<0.001).

This in vitro study shows that the analysis of the pressure profile at the dialysis needle is useful for early detection and localization of hemodialysis vascular access stenosis, independent of heart rate and flow level.