Hemodialysis pH Buffer Measurement Bypass

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Solution Overview

Problem

Current systems for hemodialysis, hemofiltration, and peritoneal dialysis face challenges in accurately measuring and managing the pH and buffer concentration of dialysate fluids, particularly in regenerative systems where sorbent materials can unpredictably alter hydrogen ion and bicarbonate levels, affecting patient outcomes.

Innovation Solution

A fluid therapy system incorporating a pH-buffer management unit positioned between a sorbent regeneration unit and a dialyzer, with a bypass flow path and sensors for conductivity measurement, allowing for precise control and monitoring of acid and base feeds, and including a degasser and replacement flow loop to manage fluid characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If sorbent regeneration unit is used to remove waste species from dialysate, then dialysate purification is improved, but pH and buffer concentration become unpredictable

Engineering Contradiction:
Improvedialysate purificationVSAvoidpH and buffer concentration measurement
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

A bypass flow path is introduced as an intermediary pathway that diverts a portion of the dialysate flow around the sorbent regeneration unit. This allows the measurement system to access dialysate that has not been altered by the sorbent materials, enabling accurate pH and buffer concentration measurements while the main flow continues to be purified by the sorbent regeneration unit.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If bypass flow path is introduced for measurement, then measurement precision is improved, but device complexity increases

Engineering Contradiction:
ImprovepH and buffer concentration measurementVSAvoidfluid flow path configuration
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The bypass flow path is designed to serve multiple functions: it provides a reference dialysate sample for accurate pH and buffer concentration measurements, maintains system pressure balance, and allows the measurement system to operate independently of the sorbent regeneration process. This multi-functionality reduces the overall system complexity despite the additional flow path.

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

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 measurement and control of dialysate pH and buffer concentration, improving patient outcomes by maintaining therapeutic acid-base balance and optimizing dialysate composition during treatments.

Implementation Method 1

a conductivity sensor in fluid communication with the fluid flow path and being positioned downstream of the fluid characteristic management unit along the fluid flow

Methodology Applied
Scientific EffectElectrical conductivity measurement: Conduction (electrical)

Implementation Method 2

The fluid characteristic management unit of the fluid therapy system can include at least one of a thermal conductivity sensor and an electrical conductivity sensor

Methodology Applied
Scientific EffectThermal conductivity measurement: Conduction (thermal)

Implementation Method 3

a degasser in fluid communication with the fluid flow loop and being positioned downstream of the sorbent regeneration unit along the fluid flow

Methodology Applied
Scientific EffectGas-liquid separation: Decomposition (biological)

Data Source

PatentEP3438641B1Ph buffer measurement system for hemodialysis systems
Publication Date: 2023.06.07 MEDTRONIC INC
  • EP3438641B1 patent drawingFigure 1
  • EP3438641B1 patent drawingFigure 2
  • EP3438641B1 patent drawingFigure 3

AI summary

A fluid therapy system comprising a fluid flow path in fluid communication with a dialyzer, a sorbent regeneration unit, and a fluid characteristic management unit, the fluid characteristic management unit being positioned between the sorbent regeneration unit and the dialyzer along a fluid flow.