This diagram shows a graft undergoing stenosis. The stenosis reduces the internal diameter of vessel and as a result intra-access pressure increases at the venous and arterial needle sites.

Intra-access pressure will also increase and decrease with the mean arterial pressure (MAP).

Vasc-Alert uses venous pressure and MAP to predict access port closure. These data are recorded by the dialysis equipment and stored on a local server. Vasc-Alert takes this standard information and enters it into an algorithm. The result of the calculation is used as a measure of the degree of stenosis or blockage present in the access site. A reading of .55 or larger is considered as a 'high' value. (This trigger has been determined empirically.) If three treatments in succession generate a 'high' reading, an alert is sent to the medical team that the access site of this patient needs attention.

Because this system works with data already collected as a by-product of the dialysis treatment, there are no additional procedures imposed on the center staff.