Recirculation Detection in Dialysis via UV Absorbance

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Solution Overview

Problem

Current methods for determining recirculation in dialysis shunts require the administration of a bolus, which can affect blood and dialysis liquid, and are prone to measurement errors due to variations in extracorporeal line systems.

Innovation Solution

A method that adjusts blood flow from a reference value to a target value using machine-related parameters, correlating sensor data from the dialysis liquid to determine recirculation without additional apparatus on the blood side, utilizing a UV sensor for absorbance measurements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a bolus is administered to determine recirculation, then recirculation measurement can be performed, but it affects blood and dialysis liquid and causes measurement errors

Engineering Contradiction:

Improverecirculation measurement accuracyVSAvoidbolus effect on blood and dialysis liquid

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The invention extracts the measurement function from the blood side to the dialysis liquid side. Instead of administering a bolus to blood and measuring its effect, the system measures the effect of blood flow changes directly on the dialysis liquid through the membrane, eliminating the need for bolus administration and its associated harmful effects

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The dialysis membrane acts as an intermediary between the blood and dialysis liquid. The system uses the membrane's selective permeability to transfer markers from blood to dialysis liquid, allowing indirect measurement of recirculation without direct bolus injection into the patient's bloodstream

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If complex bolus-based methods are used to determine recirculation, then recirculation can be detected, but the device complexity increases

Engineering Contradiction:

Improverecirculation detection capabilityVSAvoidmeasurement system complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The system uses the dialysis apparatus's own components (pump, dialyzer, UV sensor already present in the dialysis circuit) to perform recirculation measurement. The blood pump itself is used to create the flow changes needed for measurement, and the UV sensor in the dialysis liquid line detects the markers, eliminating the need for separate measurement devices

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The invention makes existing dialysis components serve multiple functions. The blood pump is used both for its primary function of circulating blood and for creating controlled flow changes for recirculation measurement. The UV sensor in the dialysis liquid line is used both for monitoring dialysis liquid quality and for detecting recirculation markers

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Productivity

If recirculation is not determined accurately, then treatment continues, but dialysis efficiency decreases

Engineering Contradiction:

Improvedialysis treatment efficiencyVSAvoidrecirculation determination accuracy

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The system implements continuous feedback measurement of recirculation during the dialysis treatment. The UV sensor continuously monitors the dialysis liquid for marker concentration, and the control unit uses this information to calculate recirculation percentage in real-time, allowing the treatment efficiency to be assessed and adjusted during the procedure

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system performs recirculation measurement at the beginning of the dialysis treatment to establish baseline conditions. By measuring recirculation early in the treatment, the system can determine whether the shunt is functioning properly before committing to the full treatment duration, allowing for early intervention if recirculation is excessive

Inventive Principle:

Principle #10Preliminary action

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

Enables accurate recirculation determination without bolus administration, accounting for system-specific variations, and improving dialysis efficiency by correlating absorbance values with clearance calculations.

Implementation Method 1

utilizing a UV sensor for absorbance measurements

Methodology Applied

Scientific EffectAbsorbance measurement: Absorption Spectroscopy

Data Source

PatentUS9579439B2Method and device for determining a recirculation state

Publication Date: 2017.02.28 B BRAUN AVITUM

AI summary

A method and a device for determining a recirculation during a dialysis on the basis of the response of the dialysis system to an alteration of a system-related operating value are described. Recirculation may be determined by establishing, at the side of the dialysis liquid, a reference parameter that represents the concentration of uremic toxins from the extracorporeal circulation, and calculating a target parameter for a system-related target operational value from the reference parameter, presetting the system-related target operational value and establishing an actual parameter related to the system-related target operational value, determining an actual comparative value from the actual parameter and the reference parameter related to the system-related target operational value and comparing the actual comparative value with a system-specific target comparative value related to the system-related target operational value, and converting the comparison result into a recirculation degree.