Hemodialysis Access Graft with Sensors

Period of Performance: 09/30/2004 - 09/30/2005


Phase 1 SBIR

Recipient Firm

Cardiohealth Systems
Livermore, CA 94551
Principal Investigator


DESCRIPTION (provided by applicant): Vascular access-related issues account for up to 36% of hospitalizations among hemodialysis patients, and the annual cost of vascular access morbidity is estimated to be at least $8,000 per patient-year. Recently, the National Kidney Association and American Medical Association identified the need for regular monitoring of AV grafts for early detection of stenosis. Existing diagnostic tools such as ultrasound imaging and Doppler flow can be used to monitor AV graft patency but require a trained operator and can be time consuming and expensive. Less expensive techniques such as recirculation percentage, and venous or dialysis pressure have proven unreliable. Intragraft pressure on the other hand has demonstrated good correlation with stenosis but accurate measurements are invasive and can require special equipment and take time. We propose to develop a novel synthetic AV graft concept that incorporates a sensor element near each end of the graft. The integrated sensors provide a direct measurement of the pulsatile intragraft pressure near the artery (AP) and vein anastomosis (VP). The ratio of AP & VP to systolic pressure change significantly with the degree of stenosis (or thrombosis). In addition to measuring these ratios our sensor concept has the necessary time response to measure the pressure pulse during a complete cardiac cycle. This additional information can be used to improve accuracy, reduce sensitivity to changes in graft compliance and normalize for patient-to-patient blood pressure changes. Several sensor configurations have been considered that can be easily incorporated into the polytetraflouroethylene (PTFE) AV grafts now commonly used. In the preferred system the integrated sensors are passive requiring no internal power source and can be easily measured with a non-contact radio frequency (RF) diagnostic device.