Relative Pump Calibration for Dialysis Ultrafiltration Control

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing dialysis apparatuses face challenges in accurately controlling ultrafiltration due to noise issues from balancing devices, mechanical wear leading to leaks, and the high cost and complexity of advanced flow meters required for precise control.

Innovation Solution

A dialysis apparatus with a control unit that calibrates and controls volumetric pumps to establish a bypass flow path, determining the relation between their stroke volumes, allowing for accurate ultrafiltration control without the need for complex balancing devices or flow meters, thereby reducing noise and increasing robustness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a passive balancing device with switching chambers is used to control ultrafiltration, then ultrafiltration control is achieved, but audible noise is produced and mechanical wear occurs

Engineering Contradiction:

Improveultrafiltration control accuracyVSAvoidaudible noise

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The invention removes the noisy balancing device with switching chambers from the system. Instead, it uses two pumps (fresh pump and spent pump) that directly control dialysis fluid flow into and out of the dialyzer, eliminating the source of audible noise while maintaining ultrafiltration control through frequency modulation of the pumps

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention replaces the mechanical balancing device with cutoff valves with an electronic control system that modulates the operating frequencies of the fresh pump and spent pump. This substitution eliminates mechanical wear and switching noise while achieving precise ultrafiltration control through electronic frequency adjustment

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If a passive balancing device with cutoff valves is used to control ultrafiltration, then ultrafiltration control is achieved, but mechanical wear leads to leaks

Engineering Contradiction:

Improveultrafiltration control accuracyVSAvoidvalve leakage

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The invention removes the cutoff valves from the system entirely. Ultrafiltration control is achieved by independently controlling the flow rates of the fresh pump and spent pump through frequency modulation, eliminating the mechanical components that suffer from wear and leakage

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention replaces the mechanical cutoff valves with an electronic control system that adjusts pump operating frequencies. This substitution eliminates mechanical wear and associated leakage problems while maintaining reliable ultrafiltration control

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If advanced flow meters are used to control ultrafiltration, then measurement precision is improved, but device complexity and cost increase

Engineering Contradiction:

Improveflow measurement accuracyVSAvoidflow meter complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The invention replaces complex advanced flow meters with a simplified control system that uses frequency modulation of volumetric pumps. By controlling the ratio of operating frequencies between the fresh pump and spent pump, the system achieves accurate ultrafiltration control without requiring complex flow measurement devices

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The pumps themselves serve as flow control devices through frequency modulation. The control unit directly adjusts the operating frequencies of the fresh pump and spent pump based on the desired ultrafiltration rate, eliminating the need for separate flow meters and their associated complexity

Inventive Principle:

Principle #25Self-service

Data Source

PatentUS10328192B2Relative pump calibration for ultrafiltration control in a dialysis apparatus

Publication Date: 2019.06.25 GAMBRO LUNDIA AB

AI summary

A control unit (30) is arranged to control a dialysis fluid distribution system (12) comprising two volumetric pumps (P1, P2) and a dialyzer (13). The control unit (30) is operable in a calibration mode, to establish a bypass flow path that bypasses the dialyzer (13) and extends between the pumps (P1, P2) and to operate the pumps (P1, P2) at first and second calibration speeds so as to balance the flow rates generated by the pumps (P1, P2), e.g. based on a measured pressure or fluid level in dialysis fluid distribution system (12). The control unit (30) determines, based on the first and second calibration speeds, a relation between the stroke volumes of the pumps (P1, P2). The control unit (30) is further operable in a treatment mode, to establish a main flow path that extends between the first and second pumps (P1, P2) via the dialyzer (13) and to control the first and second pumps (P1, P2), based on the relation between their stroke volumes, to operate at a respective treatment frequency so as to generate a selected ultrafiltration rate in the dialyzer (13).