Long-term dialysis success and cost is dependent on maintaining a patient's vascular access, a surgically- created artery-vein bypass region that can permit high blood flow. During dialysis, blood is drawn from a needle in the arterial side of the access, filtered by a hemodialysis unit, and then returned to the patient through a second downstream needle. The vascular access is also known as the Achilles Heel of hemodialysis, as maintaining the high flow characteristics (access patency) is critical to achieving efficient dialysis treatment. Vascular accesses are subjected to monitoring and surveillance to identify internal narrowing (stenosis) which can lead to access blockage (thrombosis). The goal of access monitoring is to pre- emptively treat stenosis with a routine surgical procedure before thrombosis occurs. Current access monitoring relies on skilled operators and specialized equipment and cannot be effectively applied to all patients due to economic realities within the hemodialysis standard-of-care. We propose clinical experiments to demonstrate and evaluate new approaches for non-invasive screening of hemodialysis vascular access patency. We are interested in studying the feasibility of autonomously gathering vascular signals using digital stethoscopes and skin temperature measurements to provide a continuous and real-time measure of arteriovenous graft patency. We will pursue this research to answer hypotheses regarding the reproducibility and feasibility of this non-invasive monitoring method, and to demonstrate innovative technology to enable clinical application. A second objective of this work is to train Steve Majerus to be an independent researcher capable of investigating future directions for vascular health technology. Our research plan will be conducted through two objectives. Objective 1 will conduct a clinical study at the Cleveland VA Midtown Hemodialysis Center in which digital stethoscopes and infrared (IR) thermometers will be used to gather non-invasive signals near patient's vascular accesses. These signals have been shown to be accurate indicators of access patency; we seek to understand the signal characteristics and variability across patients and within patients on chronic dialysis. Objective 2 will determine the feasibility of non-invasively measuring vascular sounds and skin temperatures using wireless electronics. This is an important experiment to understand the reproducibility and variability of this approach. To make an impact within the realities of over-loaded dialysis clinics, the measurement method must be convenient to use and accurate when used by a non-physician. The limitations of the proposed wireless approach will be assessed to determine prototype feasibility and future directions. This study aims to pursue hypothesis-driven research while producing innovative platform technologies in the fields of vascular signal analysis and wireless, wearable sensor design. A comprehensive analysis of phonoangiograms and skin temperature measurements relative to vascular access stenosis level and location has not yet been published. Published examples of wireless screening tools have relied on traditional auscultation via a skilled operator. We seek to demonstrate the feasibility of state-of-the-art electronics and sensor integration technology that is suitable for clinical deployment. This technology would be an excellent candidate for clinical translation as it could enable simple screening of vascular access patency within the economic constraints of freestanding dialysis clinics.
The primary goal of this project is to investigate new techniques to rapidly screen vascular access patency in hemodialysis patients. The VHA cares for more than 35,000 veterans with kidney failure and this number is increasing due to a clinical trend of providing dialysis therapy over prolonged patient lifespans. Long-term dialysis success and cost is dependent on proper health of the patient's vascular access. Recent findings have demonstrated the feasibility of non-invasively determining vascular access patency. These methods could enable high-frequency, low-cost screening of patients in their homes or during regular dialysis sessions. The reproducibility of this approach, and clinical feasibility of autonomously collecting this data, ha not yet been demonstrated. Enabling new vascular access screening methods would enhance the quality of care for veterans on chronic dialysis and could reduce the financial impact of regular access surveillance on the VHA.
| Majerus, Steve J A; Fletter, Paul C; Ferry, Elizabeth K et al. (2017) Suburothelial Bladder Contraction Detection with Implanted Pressure Sensor. PLoS One 12:e0168375 |
| Karam, Robert; Bourbeau, Dennis; Majerus, Steve et al. (2016) Real-Time Classification of Bladder Events for Effective Diagnosis and Treatment of Urinary Incontinence. IEEE Trans Biomed Eng 63:721-9 |
