Dialysis Membrane Conditioning via Controlled Ultrafiltration

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Solution Overview

Problem

Dialysis machines exhibit uneven local sieving coefficients along the dialyzer membrane, leading to inconsistent membrane conditioning and increased albumin loss during treatment due to varying transmembrane and oncotic pressures.

Innovation Solution

A dialysis machine with a control unit that implements a conditioning cycle with an ultrafiltration rate exceeding blood flow, creating a pressure gradient for uniform membrane exposure to blood proteins, reducing albumin loss by ensuring even membrane conditioning across the dialyzer length.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of substance

If conventional dialysis treatment is performed with normal ultrafiltration rates, then treatment proceeds normally, but membrane conditioning remains uneven leading to high albumin loss

Engineering Contradiction:
Improvealbumin lossVSAvoiduniformity of membrane conditioning
Core Design Contradiction:
Loss of substanceVSManufacturing precision

Solution Approach 1:

The invention applies preliminary action by performing a conditioning cycle at the beginning of dialysis treatment to prepare the membrane before actual therapy. This preliminary ultrafiltration process creates a more uniform secondary membrane structure in advance, preventing excessive albumin loss during subsequent treatment phases.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The invention changes key parameters during the conditioning phase by setting ultrafiltration rate to exceed blood flow rate (reversing the normal relationship), and maintaining dialysate flow at 0-300 ml/min. These parameter changes create uniform transmembrane pressure distribution that promotes even membrane conditioning and reduces albumin loss.

Inventive Principle:
Principle #35Parameter changes

2Productivity

If ultrafiltration rate is increased to improve membrane conditioning, then conditioning speed increases, but pressure gradient becomes uneven across the dialyzer membrane

Engineering Contradiction:
Improveconditioning speedVSAvoidtransmembrane pressure distribution
Core Design Contradiction:
ProductivityVSStress or pressure

Solution Approach 1:

The invention applies equipotentiality by creating a more uniform pressure distribution across the dialyzer membrane during conditioning. By setting dialysate flow to 0-300 ml/min and making ultrafiltration rate exceed blood flow rate, the system achieves relatively equal transmembrane pressure at all points along the membrane, enabling uniform conditioning without pressure hotspots.

Inventive Principle:
Principle #12Equipotentiality

3Manufacturing precision

If dialysate flow is reduced to enhance membrane conditioning uniformity, then conditioning evenness improves, but treatment efficiency may be reduced

Engineering Contradiction:
Improveuniformity of membrane conditioningVSAvoidtreatment efficiency
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The invention applies periodic action by implementing a distinct conditioning cycle phase at the beginning of treatment, separated from the subsequent therapy phase. During this temporary conditioning period, dialysate flow is reduced to 0-300 ml/min to achieve uniform membrane preparation, then normal treatment parameters are restored for efficient albumin removal while benefiting from the pre-conditioned membrane.

Inventive Principle:
Principle #19Periodic 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

The solution achieves a uniform secondary membrane structure, reduces albumin loss, and enhances hemocompatibility by ensuring even filtration and reduced sieving coefficients, minimizing the loss of essential proteins and substances.

Implementation Method 1

a dialyzer (104) having a dialysis membrane (105) which separates its blood side from its dialysate side

Methodology Applied
Scientific EffectDiffusion: Diffusion

Implementation Method 2

the deposition of albumin and other blood components on the dialysis membrane forms a secondary membrane

Methodology Applied
Scientific EffectOsmosis: Osmosis

Implementation Method 3

an ultrafiltration rate which exceeds the blood flow through the dialyzer... A pressure gradient is created across the dialysis membrane, which is accompanied by a withdrawal of fluid from the blood

Methodology Applied
Scientific EffectPressure gradient: Pressure Gradient

Implementation Method 4

the ultrafiltration rate can be regulated, for example, using an ultrafiltration pump

Methodology Applied
Scientific EffectUltrafiltration: Reverse Osmosis

Implementation Method 5

the deposition of albumin and other blood components on the dialysis membrane forms a secondary membrane, which leads to a desirable better sieving effect for large proteins such as albumin

Methodology Applied
Scientific EffectAdsorption: Adsorption

Implementation Method 6

the screening effect for large proteins such as albumin is greatly improved

Methodology Applied
Scientific EffectSieving: Molecular Sieve

Data Source

PatentEP3484537B1Dialysis device having a control unit for performing conditioning of the dialysis membrane
Publication Date: 2021.06.02 FRESENIUS MEDICAL CARE DEUTSCHLAND GMBH
  • EP3484537B1 patent drawingFigure 1
  • EP3484537B1 patent drawingFigure 2
  • EP3484537B1 patent drawingFigure 3

AI summary

The invention relates to a dialysis device, comprising an extracorporeal blood circuit, a dialyzer, and a dialysate circuit, wherein a blood pump is arranged in the extracorporeal blood circuit, wherein the dialyzer has a dialysis membrane, which separates the blood side of the dialyzer from the dialysate side of the dialyzer, wherein the dialysis device has a control unit, which is designed to perform a conditioning cycle, which comprises a conditioning phase, in which an ultrafiltration rate exceeds the blood flow through the dialyzer, which blood flow is conveyed by the blood pump.