Theory and validation of access flow measurement by dilution technique during hemodialysis

Abstract

The theory shows that access flow can be measured by the dilution technique by reversal of the blood dialysis lines with the venous outlet facing the access stream: (1.) with one dilution sensor in arterial line and two injections Equation (6); (2.) with two matched dilution sensors on the venous line and on the arterial line and one injection Equation (8); (3.) with blood sampling as for recirculation measurement using BUN or other methods in Equation (12). In all cases, accurate measurement of hemodialysis blood flow is required. The results of this bench validation demonstrate that dialysis blood flows, in the clinical range of 200 to 350 ml/min or more, create good mixing conditions in a vascular access model. Accurate measurements are provided for all clinically significant ranges of access flows, needle positions, and vascular access inner diameters. This simple, non-invasive, and inexpensive technique shows great promise for routine diagnosis of vascular access failure in hemodialysis patients.

Far-Infrared Therapy

“…The technique is used widely and extensively validated in the literature (17). In brief, the technique uses two ultrasound sensors that are attached to the two HD tubing lines, one to the arterial and the other to the venous catheters, approximately 3 to 5 in from the connection of the tubing to the dialysis needles.…”

A Prospective Controlled Trial on Effect of Percutaneous Transluminal Angioplasty on Functioning Arteriovenous Fistulae Survival

“…Access surveillance program was based on Qb monitoring and urea-based access recirculation (Ru) during the period between January 1995 and January 1998 and on Qb monitoring, ultrasound dilution recirculation (Rhd), and Qa measurements by Transonic HD01 monitor (14) from February 1998 onwards.…”

“…Qa was measured quarterly by ultrasound dilution technique with Transonic HD01 monitor (Transonic System Inc., Ithaca, NY), as described elsewhere (14). AVF were cannulated with 15-gauge needles, and the "arterial" needle was placed in the main trunk of the feeding vein proximal to any collateral veins and facing the incoming blood flow (15).…”

The Measurement of Hemodialysis Access Blood Flow by a Conductivity Step Method

“…Reduced or falling levels of Qa indicate access dysfunction and predict thrombosis (1). Most Qa measurements use indicator dilution techniques to measure the amount of recirculation induced by reversal of blood lines.…”

“…Most Qa measurements use indicator dilution techniques to measure the amount of recirculation induced by reversal of blood lines. This plus the dialysis circuit flow rate (Qb, ml/min) allows for the calculation of Qa (1). One methodology for Qa measurement involves ultrasound velocity measurements of flowing blood and their dilution by saline using the Transonics hemodialysis monitor (Transonics, Inc., Ithaca, NY).…”