A New System to Monitor Arteriovenous Fistula

The arteriovenous fistula (AVF) is the preferred vascular access for hemodialysis in end-stage kidney disease patients. AVF management is essential for a successful dialysis treatment and can influence long-term patient survival. Physical examination is the first step to diagnose and treat a malfunctioning AVF and includes palpation of AVF thrill and auscultation of bruit sounds. Guidelines recommend frequent visits during AVF maturation and throughout the dialysis period, with large deployment of financial and human resources. A tele-monitoring system can enable more frequent monitoring and earlier recognition of stenoses. A new device based on a wide-bandwidth force sensor is proposed to simultaneously record the sphygmic wave, the thrill and the bruit sounds. The sensor was applied onto the arm of a patient, in proximity to the AVF. An electrocardiography lead was acquired simultaneously as reference. The raw signal provided by the sensor was appropriately processed to isolate the sphygmic wave, the thrill, and the bruit sounds. The morphology of the sphygmic wave exhibits the classic features (e.g., systolic peak, dicrotic notch). The thrill component is characterized by a continuous oscillation at a few Hz with variable amplitude, which is consistent with tactile sensations perceived during palpation. The bruit sounds provide an acoustic perception very similar to that obtained with a common stethoscope. The encouraging results of this proof-of-concept study represent a first step toward a quantitative monitoring of AVF function.