How Vasc-Alert Works

Vasc-Alert is technically a medical device for vascular access surveillance, but you can think of it as a service where each week we send a report to your facility, identifying patients who are at risk for thrombosis. The way we do this is by deriving the static pressure at the tip of the needle as a marker for stenosis, i.e. the higher the pressure, the greater the occlusion.

We calculate the static pressure by taking the treatment records of your patients as input into an algorithm that eliminates the resistance in the circuit due to the tubing and needles. This patented and FDA approved method literally tests the access with each treatment, providing your vascular access manager with a graphical picture of what is actually going on inside the access, i.e. is the stenosis growing and if so, at what rate?

A simple way explanation of how the algorithm works is the following:

DoctorsCorner_AlgorithmExample

The equation strips away the pressure in the drip chamber used to overcome the resistance of the tubing and needle, leaving the pressure in the access itself. Dividing the derived static pressure by the patient’s MAP normalizes the result and produces the Venous Access Pressure Ratio or VAPR.

The VAPR for each treatment is then presented graphically:DoctorsCorner_Graph

By testing the access during each treatment, the clinical staff can observe a trend, providing much more information to staff than a single measurement about what is going on inside the access.

Vasc-Alert was developed at Henry Ford Health Systems in Detroit and was first published in a paper in 2002 in the American Journal of Kidney Disease titled:

Dynamic Venous Access Pressure Ratio Test for Hemodialysis Access Monitoring

The elegance of this approach is that there is no need for staff people to spend time testing the access and calculating the results, thus freeing up precious time for patient care. It is self-documenting and can be accessed online so that your entire clinical team can participate in improving access care and reducing conversions to catheters. Furthermore, the service actually pays for itself by reducing missed treatments and catheter usage by AV access capable patients.