Dialyzer Flow Reversal for Vascular Access Rate Measurement
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Solution Overview
Problem
Existing blood treatment machines face challenges in accurately determining vascular access flow rates without the need for complex and costly equipment or procedures, such as manual flow reversal and bolus techniques, which can introduce errors and increase treatment costs.
Innovation Solution
A control device and method that calculates vascular access flow rate by comparing in-vivo clearance before and after reversing the blood flow direction within the dialyzer, using standard components of the dialysis machine to determine the access flow rate without requiring additional line sets or cassettes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If color Doppler ultrasound or MRI is used to measure flow through AV fistulas and grafts, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The dialysis machine uses its own built-in sensors and processing capabilities to measure access flow rate by monitoring recirculation levels during normal dialysis operation. The system leverages existing components (blood flow sensors, conductivity sensors, and control units) to perform self-diagnosis and measurement without requiring external specialized equipment like Doppler ultrasound or MRI machines.
2Measurement precision
If manual flow reversal or bolus techniques are used to determine access flow rate, then measurement precision is improved, but ease of operation deteriorates
Solution Approach 1:
The system continuously monitors recirculation levels by measuring blood flow characteristics and conductivity changes in real-time during dialysis. The control unit processes this feedback information to automatically calculate access flow rate, eliminating the need for manual intervention, flow reversal operations, or bolus injection techniques that complicate the procedure.
3Measurement precision
If intermittent flow reversal is implemented to measure access flow rate, then measurement precision is improved, but productivity deteriorates
Solution Approach 1:
The access flow rate measurement is performed continuously or periodically during normal dialysis treatment without interrupting the blood flow or requiring flow reversal. The system monitors recirculation levels and calculates access flow rate using data obtained during routine dialysis operation, maintaining continuous productive action rather than pausing for measurement procedures.
4Measurement precision
If dedicated line sets or cassettes with switching devices are used for flow reversal, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The dialysis machine's existing blood transport system and sensors are designed to perform multiple functions: both the routine dialysis treatment and the access flow rate measurement. The same blood flow sensors and control units used during normal operation are utilized to monitor recirculation and calculate access flow rate, eliminating the need for dedicated measurement line sets or cassettes with specialized switching devices.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach simplifies the measurement of vascular access flow rate, reducing operational complexity and costs while maintaining accuracy, thereby ensuring efficient blood treatment by minimizing recirculation.
Implementation Method 1
a) measuring a first value of conductivity in the treatment fluid at the inlet to the dialyzer and a second value of conductivity in the treatment fluid at the outlet from the dialyzer
Data Source
Figure 1~2B
Figure 3A~3B
Figure 4~5
AI summary
A device for determining the access flow rate of a patient when connected to a blood treatment machine performs a measurement phase (40), in which the blood treatment machine is caused (41, 43) to operate in first and second operating states, wherein the second operating state at least differs from the first operating state by a change of flow direction of blood or treatment fluid through a dialyzer of the blood treatment machine. Based on sensor values representing a fluid property (42, 44) of the treatment fluid in the first and second operating states, the device computes (45) a measurement value of comparison parameter (e.g. a ratio or a difference) that compares treatment efficiency in the first operating state to treatment efficiency in the second operating state, and determines (46), based on the measurement value, an estimated value of the access flow rate.