Substitution Volume Compensation in Blood Treatment Control

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Solution Overview

Problem

Existing blood treatment devices struggle to automatically and easily compensate for deviations between the ideal target volume and the actual controlled volume of the supplied substitution solution during dialysis therapy.

Innovation Solution

A control unit calculates the difference between the ideal target volume and the actual controlled volume and temporarily increases the substitution solution pump flow rate by a predetermined percentage, typically between 1% and 5%, until the deviation is eliminated.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a complex feedback control system is used to compensate for substitution volume deviations, then the accuracy of substitution volume is improved, but the device complexity increases

Engineering Contradiction:
Improvesubstitution volume accuracyVSAvoidcontrol system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent implements a feedback control mechanism where the control unit continuously monitors the actual substitution volume delivered and compares it to the target volume. When a deviation is detected, the system automatically adjusts the substitution solution pump flow rate by a predetermined percentage to compensate for the discrepancy, ensuring accurate delivery of the intended substitution volume without requiring complex manual interventions or multiple sensors.

Inventive Principle:
Principle #23Feedback

2Measurement precision

If the substitution solution pump flow rate is increased by a predetermined percentage to compensate for volume deviations, then the substitution volume accuracy is improved, but the risk of exceeding the target volume increases

Engineering Contradiction:
Improvesubstitution volume accuracyVSAvoidvolume delivery reliability
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent applies partial action by increasing the pump flow rate by a predetermined percentage (not a fixed amount) when volume deviations are detected. This proportional adjustment allows the system to compensate for losses without applying excessive correction that could cause the total delivered volume to exceed the target. The control unit monitors the cumulative volume delivered and stops the percentage increase when the target is reached, ensuring reliable and accurate volume delivery.

Inventive Principle:
Principle #16Partial or excessive action

3Device complexity

If manual compensation methods are used for substitution volume deviations, then the device complexity is reduced, but the ease of operation deteriorates

Engineering Contradiction:
Improvecontrol system complexityVSAvoidvolume compensation ease
Core Design Contradiction:
Device complexityVSEase of operation

Solution Approach 1:

The patent implements self-service automation where the control unit automatically detects substitution volume deviations and adjusts the pump flow rate without requiring manual intervention. The system independently calculates the volume discrepancy, determines the appropriate percentage increase in flow rate, and executes the correction automatically. This eliminates the need for operators to manually calculate and adjust pump settings, significantly improving ease of operation while maintaining simple device architecture.

Inventive Principle:
Principle #25Self-service

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 allows for automatic compensation of volume discrepancies, ensuring the ideal target volume is achieved without exceeding the actual volume, thereby improving the accuracy and reliability of dialysis therapy.

Implementation Method 1

an extracorporeal blood circuit, a dialyzer and a dialyzer fluid circuit, wherein the extracorporeal blood circuit and the dialyzer fluid circuit are separated from each other by a membrane provided in the dialyzer, through which blood (using a dialyzer fluid solution) can be filtered

Methodology Applied
Scientific EffectFiltration: Filter (physical)

Data Source

PatentEP3797804B1Blood treatment device with automatic substitution volume compensation
Publication Date: 2026.01.28 B BRAUN AVITUM
  • EP3797804B1 patent drawingFigure 1
  • EP3797804B1 patent drawingFigure 2
  • EP3797804B1 patent drawingFigure 3

AI summary

The disclosure relates to a blood treatment device (2) comprising: an extracorporeal blood circuit (4), a dialyzer (6) and a dialyzer fluid circuit (8), wherein the extracorporeal blood circuit (4) and the dialyzer fluid circuit (8) are separated from each other by a membrane (10) provided in the dialyzer (6), through which blood can be filtered; at least one substitution solution pump (36, 56) configured to supply a substitution solution to the extracorporeal blood circuit (4) before and/or after the dialyzer (6); and a control unit (68) configured to measure a difference orto calculate a residue between an ideal target volume and an actually controlled volume of the supplied substitution solution, and to temporarily increase a controlled flow rate of the substitution solution pump (36, 56) by a predetermined fixed percentage, which is less than or equal to 5%, by appropriately controlling it, until the difference or residue between the actually controlled volume and the ideal target volume no longer exists, i.e., the actually controlled volume corresponds to the ideal target volume.