Analysis of the optical concentration curve to detect access recirculation

Area of Science:

• Nephrology
• Medical Devices
• Diagnostic Techniques

Background:

• The optical blood volume curve can exhibit rapid variations (spikes) during ionic dialysance (ID) measurements.
• The cause and significance of these spikes, particularly in relation to access recirculation, require investigation.

Purpose of the Study:

• To determine if spikes in the optical blood volume curve are associated with access recirculation during hemodialysis.
• To assess the diagnostic value of these spikes for detecting and quantifying access recirculation.

Main Methods:

• Investigated the effect of reversed blood line positioning on the blood volume curve to simulate recirculation.
• Systematically monitored for spikes during ID measurements in patients undergoing dialysis.
• Quantified access recirculation using an ultrasound dilution technique in parallel with spike observation.

Main Results:

• Reversing blood lines consistently reproduced spikes in the blood volume curve when recirculation exceeded 20%.
• Patients with access recirculation greater than 20% exhibited spikes during normal ID measurements.
• Spikes were inconsistent for recirculation between 10-20% and absent below 10% or undetectable recirculation.

Conclusions:

• The presence of spikes in the optical blood volume curve during ID measurement is a clear indicator of access recirculation.
• This phenomenon demonstrates 100% specificity when spikes are present throughout the dialysis session for all ID measurements.
• A sensitivity of 100% is achieved for detecting access recirculation greater than 20%.