Sorbent Cartridge Fluid Circuits for Dialysis Monitoring

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Solution Overview

Problem

Current methods for monitoring urea clearance and dialysis adequacy in patients with end-stage renal disease are inadequate, as they rely on infrequent blood tests and cannot accurately assess urea clearance efficiency during dialysis sessions, leading to potential morbidity and mortality due to insufficient or excessive dialysis.

Innovation Solution

A sorbent regeneration system with multiple material layers, including urease-containing materials, alumina, zirconium phosphate, and activated carbon, is used to measure fluid characteristics such as conductivity and ammonium ion concentration in dialysate, allowing for continuous monitoring of urea clearance and dialysis efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If infrequent blood tests are used to monitor urea clearance, then testing cost is reduced, but measurement reliability deteriorates leading to potential morbidity and mortality

Engineering Contradiction:
Improveurea clearance monitoring reliabilityVSAvoidtime delay in urea measurement
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent replaces the mechanical/blood sampling system with an optical sensing system. Sensors detect urea concentration in dialysate fluid optically, eliminating the need for blood draws and laboratory analysis. This substitution enables continuous real-time monitoring without the time delays and costs associated with traditional blood test methods.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent uses dialysate fluid as an intermediary to indirectly measure urea clearance. Instead of measuring urea directly in blood, the system measures urea concentration in the dialysate that has contacted the patient's blood in the dialyzer. This intermediary approach provides continuous monitoring data without requiring direct blood sampling.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If continuous monitoring of urea clearance is implemented, then measurement precision is improved, but device complexity increases

Engineering Contradiction:
Improveurea clearance measurement precisionVSAvoiddialysis monitoring system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent makes the dialysate fluid serve multiple functions: it performs its primary dialysis function of removing waste from blood, and simultaneously serves as the medium for continuous urea concentration monitoring. The same fluid pathway is used for both treatment and measurement, eliminating the need for separate monitoring equipment and reducing overall system complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent merges the dialysis treatment function with the monitoring function into a single integrated system. The sensors are placed within the existing dialysate flow path, combining the therapeutic dialysis process with the diagnostic monitoring process. This integration reduces device complexity by eliminating separate blood sampling and laboratory analysis systems.

Inventive Principle:
Principle #5Merging (Combining)

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 system enables real-time monitoring of urea clearance and dialysis efficiency, providing immediate feedback to adjust treatment duration and intensity, thereby improving patient outcomes by ensuring adequate dialysis and reducing the risk of under or over-dialysis.

Implementation Method 1

a first material layer comprising a urease-containing material

Methodology Applied
Scientific EffectEnzymatic hydrolysis: Hydrolysis

Implementation Method 2

a second material layer comprising alumina, zirconium phosphate, or zirconium oxide; a third material layer comprising activated carbon

Methodology Applied
Scientific EffectAdsorption: Adsorption

Data Source

PatentEP2950839B1Fluid circuits for sorbent cartridges with sensors
Publication Date: 2020.04.01 MEDTRONIC INC
  • EP2950839B1 patent drawingFigure 1
  • EP2950839B1 patent drawingFigure 2
  • EP2950839B1 patent drawingFigure 3

AI summary

A system for measuring at least one fluid characteristic at various stages within a sorbent system has a sorbent cartridge that has at least one material layer and at least one fluid passageway in at least one location in the sorbent system to provide a diverted sample stream from the various stages. At least one fluid characteristic of the diverted sample stream is measured.