Dialysis Machine Degassing Control to Prevent Hypoxemia

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Solution Overview

Problem

Existing extracorporeal blood treatment machines, such as dialysis machines, cause hypoxemia due to complete degassing of ultrapure water, leading to increased oxygen excretion from the blood and reduced oxygen content in the venous blood, which is inefficient and potentially harmful.

Innovation Solution

A dialysis machine with a continuously adjustable throttle device controls the degassing pressure of ultrapure water to adjust the oxygen content in the fresh dialysis fluid, allowing for precise regulation of oxygen levels in the blood via the semipermeable membrane, using a sensor unit to monitor blood components and a control unit to manage the throttle device.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If complete degassing of ultrapure water is performed to ensure precise ultrafiltration, then ultrafiltration precision is improved, but oxygen content in blood decreases causing hypoxemia

Engineering Contradiction:
Improveultrafiltration precisionVSAvoidhypoxemia
Core Design Contradiction:
Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The patent applies partial degassing instead of complete degassing of ultrapure water. The throttle device is controlled to create a pressure drop that removes only a portion of dissolved gases, specifically controlling the oxygen partial pressure to remain above a threshold value (e.g., >10 mmHg). This partial action maintains sufficient ultrafiltration precision while preventing harmful hypoxemia in the patient's blood.

Inventive Principle:
Principle #16Partial or excessive action

Solution Approach 2:

The patent changes the pressure parameter of ultrapure water during degassing. By controlling the pressure drop across the throttle device, the system adjusts the extent of gas removal. The pressure is regulated to achieve a balance: enough pressure reduction to ensure precise ultrafiltration, but not so much as to completely remove oxygen and cause hypoxemia.

Inventive Principle:
Principle #35Parameter changes

2Manufacturing precision

If throttle device is made continuously adjustable to control oxygen content in dialysis fluid, then oxygen regulation precision is improved, but device complexity increases

Engineering Contradiction:
Improveoxygen regulation precisionVSAvoidthrottle device complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent implements a feedback control system where a sensor measures the oxygen partial pressure in the dialysis fluid or blood, and this measurement is fed back to the control unit. The control unit adjusts the throttle device based on the feedback signal to maintain the oxygen partial pressure within a desired range. This feedback mechanism achieves precise oxygen regulation without requiring an overly complex manually adjustable throttle device.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent replaces complex mechanical adjustment mechanisms with an automated control system. Instead of requiring manual precision adjustment of the throttle device, the system uses electronic control (motor-driven throttle or electronically controlled valve) that responds to sensor feedback. This substitution reduces mechanical complexity while improving regulation precision.

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

This approach enables safer and more efficient extracorporeal blood treatment by maintaining optimal oxygen levels in the blood, reducing hypoxemia and enhancing therapy effectiveness.

Implementation Method 1

a dialyzer with a semipermeable membrane for mass transfer between a patient's blood and a dialysis fluid

Methodology Applied
Scientific EffectDiffusion: Diffusion

Implementation Method 2

degassing occurs when the ultrapure water flows through a fixed throttle, thereby experiencing a pressure loss. The pressure is released and then passed through a degassing chamber with a large surface area. The surface allows for the efficient separation of the gas components of the ultrapure water released due to the pressure loss.

Methodology Applied
Scientific EffectPressure drop: Pressure Drop

Data Source

PatentEP4591897A1Extracorporeal blood treatment machine, computer-implemented control method for the same, and computer program
Publication Date: 2025.07.30 B BRAUN AVITUM
  • EP4591897A1 patent drawingFigure 1
  • EP4591897A1 patent drawingFigure 2~3
  • EP4591897A1 patent drawingFigure 4~5

AI summary

The disclosure relates to an extracorporeal blood treatment machine (1) for extracorporeal blood treatment, comprising a dialyzer (2), an extracorporeal blood circuit (3), a sensor unit (44) adapted to determine a blood component (SpO2B) in the blood, a degassing unit (5) with a throttle device (78) adapted to throttle gas-containing ultrapure water to a degassing pressure (pE), a pressure detection unit (81) adapted to detect the degassing pressure (pE), a mixing unit (6) adapted to mix the at least partially degassed ultrapure water with at least one concentrate to form a fresh dialysis fluid, and a control unit (54) signal-connected to the sensor unit (44), the pressure detection unit (81), and the throttle device (78), wherein the throttle device (78) is designed with a continuously adjustable throttle cross-section.which is continuously adjustable depending on a control signal (S) of the control unit (54). In addition, the disclosure relates to a control method and a computer program according to the independent claims.