Reusuable ultrasound/dilution sensors are clipped onto standard blood lines.
Accurate measurements of vascular access
recirculation and vascular access flow during dialysis are now possible through the marriage of two classic technologies: Dilution and Ultrasound Transit
Time. Termed "Ultrasound Dilution," the new technology uses the same time-proven principles of other classic dilution technologies. However, instead
of measuring differences in temperature or dye concentration following a dilution infusion, the Transonic HD01 measures the changes that occur in
the velocity of an ultrasound signal when blood is diluted with saline.
Ultrasound Transit-Time Technology
The Transonic Hemodialysis Monitor and Flow/Dilution Sensors measure the
velocity of ultrasound in blood as well as the volume flow. Transducers inside the clip-on sensors pass ultrasonic signals back and forth, alternately intersecting the
flowing liquid in upstream and downstream directions (see schematic diagram). The HD01 Monitor derives an accurate measure of the changes in the "transit
time" that result from the motion of the liquid inside the tube. The difference between the integrated upstream and downstream transit times is a measure of
volume flow; the integrated sum of the upstream and downstream transit times is a measure of acoustical velocity.
Simple Steps for Hemodialysis Flow-QC Monitoring:
1. One sensor is clipped onto the venous line and one onto the arterial line.
These sensors measure flow & dilution with ultrasound (described below).
2. A 10 ml indicator bolus of 0.9% NaCl is infused into the port above the
bubble trap in the venous line.
3. The saline indicator dilutes the blood and the resulting change in
concentration is detected as it passes through the venous sensor producing a concentration curve.
4. If recirculation is present, a portion of the bolus will immediately pass
through the sensor on the arterial line. This produces a second concentration curve.
5. Results are calculated automatically and are displayed on the computer
screen within minutes.
6. For access flow measurements a similar procedure is followed with the
dialysis lines reversed.
