Bi-directional Pump Fluid Balance Control in Dialysis

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Solution Overview

Problem

Current dialysis systems face challenges in accurately and efficiently balancing fluid levels during renal therapy, often requiring additional equipment like scales and highly accurate pumps, which increase the size, weight, and cost of the system, and can lead to inaccuracies in fluid removal due to factors like fluid leaks and gas bubbles.

Innovation Solution

A bi-directional control pump in a controlled compliant dialysate flow loop with inflow and outflow sensors, eliminating the need for additional pumps between sensors and the dialyzer, allows for precise fluid balance by adjusting the pump rate based on the difference in flow rates detected by the sensors, ensuring accurate fluid removal or addition without extra equipment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If additional scales and control systems are used to balance fluid levels, then fluid balance accuracy is improved, but device complexity and system cost increase

Engineering Contradiction:
Improvefluid balance accuracyVSAvoidsystem complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent removes the need for additional scales and complex control systems by extracting the fluid balance measurement function directly into the dialyzer housing. The housing itself serves as the measurement container, eliminating separate weighing components while maintaining measurement capability.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The dialyzer housing is designed to serve multiple functions: it acts as both the dialysis chamber and the weighing container. This multi-functionality eliminates the need for separate scales and control systems, reducing device complexity while maintaining fluid balance measurement accuracy.

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

2Manufacturing precision

If balance chambers with fluid removal pumps are used, then fluid removal control is improved, but device complexity and fluid volume requirements increase

Engineering Contradiction:
Improvefluid removal control accuracyVSAvoidsystem complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent eliminates balance chambers and fluid removal pumps by extracting the fluid removal function directly through the dialysis membrane. Fluid is removed via ultrafiltration during normal dialysis operation, eliminating the need for separate balance chamber systems.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The system uses the dialysis process itself to achieve fluid removal. The concentration gradient across the dialysis membrane naturally drives ultrafiltration, eliminating the need for additional pumps or balance chambers while maintaining precise fluid removal control.

Inventive Principle:
Principle #25Self-service

3Measurement precision

If multiple pumps with coordinated control are used, then fluid balance accuracy is improved, but device complexity and cost increase

Engineering Contradiction:
Improvefluid balance accuracyVSAvoidsystem cost
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent removes the need for multiple coordinated pumps by extracting the fluid balance function into the dialyzer housing design. The housing volume change directly reflects fluid balance, eliminating complex pump coordination systems.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The system uses passive volume measurement through the dialyzer housing itself. The housing expands or contracts based on fluid volume changes, providing automatic feedback without requiring active pump control or coordination.

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 solution enables precise control of fluid balance during dialysis, reducing the risk of hypervolemia or hypotension, and eliminates the need for balance chambers and scales, resulting in a more compact, cost-effective, and accurate fluid management system.

Implementation Method 1

a dialysis flow loop having a controlled volume and in fluid communication with a dialyzer having a dialysis membrane

Methodology Applied
Scientific EffectSemipermeable Membrane: Semipermeable Membrane

Implementation Method 2

a bi-directional control pump in a controlled compliant dialysate flow loop

Methodology Applied
Scientific EffectPump: Pump

Data Source

PatentEP3031483B1Sensing and storage system for fluid balance
Publication Date: 2019.07.24 MEDTRONIC INC
  • EP3031483B1 patent drawingFigure 1
  • EP3031483B1 patent drawingFigure 2

AI summary

A sensing and storage system for fluid balance during dialysis is provided. The sensing and storage system has flow sensors on either side of a dialyzer in a controlled volume dialysate flow path. The sensors are positioned so that no fluid can be added to or removed from the dialysate flow path between the sensors except for that which is added or removed by action of a control pump. The sensing and storage system can have a fluid removal line for the removal of fluid from the dialysate flow loop.