Extracorporeal Blood Treatment Parameter Estimation

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Solution Overview

Problem

Existing methods for determining the effectiveness of extracorporeal blood treatments, such as hemodialysis, are limited by the need for frequent modifications in dialysis liquid conductivity/concentration, sensitivity to artifacts, and reduced operational flexibility, making it difficult to reliably calculate effectiveness parameters during treatment without impairing prescription delivery or increasing computational demands.

Innovation Solution

An apparatus and method that utilize a control unit to vary the dialysis liquid characteristic, measure downstream variations, and estimate parameters using a parametric mathematical model, allowing for frequent effectiveness parameter calculation without substantial impact on treatment prescriptions and with reduced sensitivity to noise and artifacts, using a reference portion of the downstream variation to identify the characteristic mathematical model and compute effectiveness parameters.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If frequent modifications in dialysis liquid conductivity/concentration are performed to calculate effectiveness parameters, then measurement frequency increases, but operational flexibility decreases and prescription delivery is impaired

Engineering Contradiction:

Improveeffectiveness parameter calculation frequencyVSAvoidoperational flexibility

Core Design Contradiction:

ProductivityVSEase of operation

Solution Approach 1:

The system performs preliminary characterization of the blood treatment unit by measuring its response to conductivity changes in advance. The microprocessor determines characteristic values (gain and time constant) that describe the unit's behavior, allowing subsequent effectiveness parameter calculations to be performed using these pre-determined characteristics rather than requiring frequent actual modifications to the dialysis liquid.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system creates a mathematical model (copy) of the blood treatment unit's response characteristics. Instead of repeatedly modifying the dialysis liquid to measure effectiveness, the microprocessor uses the stored characteristic values to calculate effectiveness parameters from conductivity measurements, effectively copying the unit's behavioral pattern for computational purposes.

Inventive Principle:

Principle #26Copying

2Measurement precision

If traditional methods are used to determine effectiveness parameters, then measurement accuracy may be maintained, but computational requirements increase and sensitivity to noise and artifacts increases

Engineering Contradiction:

Improveeffectiveness parameter accuracyVSAvoidcomputational requirements

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The system transforms the measurement approach by changing from direct effectiveness parameter calculation to determining characteristic values (gain and time constant) that describe the blood treatment unit's response. This parameter transformation simplifies the computational model, reducing sensitivity to noise while maintaining measurement accuracy through the use of these fundamental characteristic parameters.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If multiple specimens are taken to monitor treatment effectiveness, then measurement reliability increases, but patient risk increases and treatment time increases

Engineering Contradiction:

Improvetreatment monitoring reliabilityVSAvoidtreatment time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The system replaces the mechanical/biological process of taking multiple blood specimens with an electrical measurement system. The microprocessor monitors treatment effectiveness by measuring conductivity changes in the dialysis liquid and analyzing the blood treatment unit's response characteristics, eliminating the need for repeated blood sampling while maintaining monitoring reliability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 reliable and frequent calculation of effectiveness parameters during extracorporeal blood treatments, maintaining prescription delivery flexibility and minimizing computational requirements, while being less sensitive to measurement noise and artifacts.

Implementation Method 1

a blood treatment unit (2) having a primary chamber (3) and a secondary chamber (4) separated by a semi-permeable membrane (5)

Methodology Applied

Scientific EffectSemipermeable membrane separation: Semipermeable Membrane

Implementation Method 2

impurities and undesired substances present in the blood (urea, creatinine, etc.) may migrate by diffusive transfer from the blood into the treatment liquid

Methodology Applied

Scientific EffectDiffusive transfer: Diffusion

Implementation Method 3

a convective transfer by ultrafiltration, resulting from a positive pressure difference created between the blood side and the treatment-liquid side of the membrane

Methodology Applied

Scientific EffectUltrafiltration: Osmosis

Data Source

PatentUS10265459B2Apparatus for determining a parameter indicative of the progress of an extracorporeal blood treatment

Publication Date: 2019.04.23 GAMBRO LUNDIA AB

AI summary

An apparatus for extracorporeal treatment of blood (1) comprising a treatment unit, a blood withdrawal line, a blood return line, a preparation line and a spent dialysate line. A control unit (10) is configured to calculate values of a parameter relating to treatment effectiveness based on measures of the conductivity in the spent dialysate line. The value of the effectiveness parameter is calculated using one or more values representative of the conductivity in the spent dialysate line obtained relying on a mathematical model.