Dialysis Piston Pump Stroke Control to Prevent Overfilling
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Solution Overview
Problem
Existing dialysis systems face challenges in accurately controlling the volume flow of dialysis solution, leading to potential overfilling of patients due to construction tolerances and defects in pump performance, posing a risk to patient safety.
Innovation Solution
A pump system with adjustable mechanical piston stops, reduced working fluid volume, and variable conveying chamber sizes to precisely control the volume per piston stroke, ensuring accurate delivery of dialysis solution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If piston pumps with standard piston stroke are used to convey dialysis solution, then the conveying volume per stroke is sufficient for typical dialysis requirements, but construction tolerances and pump defects can cause overfilling of the patient
Solution Approach 1:
The patent implements a variable piston stroke mechanism that dynamically adjusts the conveying volume based on the prescribed volume. The piston stroke is reduced when the prescribed volume is small to prevent overfilling, while maintaining full stroke capability for larger volumes. This dynamic adaptation resolves the contradiction by making the pump system reliable across different operating conditions.
Solution Approach 2:
The patent changes the operational parameters of the piston pump by variable reduction of the piston stroke. A reduction mechanism is introduced that can shorten the piston travel distance based on the prescribed dialysis solution volume, thereby controlling the conveying volume to match the prescription and prevent overfilling.
2Reliability
If the piston stroke is reduced to prevent overfilling, then patient safety is improved, but the conveying efficiency and productivity of the pump system decreases
Solution Approach 1:
The system dynamically adapts the piston stroke to the actual conveying requirement. When the prescribed volume is large, the full piston stroke is utilized for high productivity. When the prescribed volume is small, the piston stroke is reduced to ensure patient safety. This dynamic behavior resolves the contradiction by optimizing both safety and efficiency based on operating conditions.
3Ease of manufacture
If standard pump construction tolerances are accepted, then manufacturing cost and complexity are reduced, but volume precision and accuracy deteriorate
Solution Approach 1:
The patent replaces reliance on precise mechanical manufacturing tolerances with a controllable mechanical reduction mechanism. Instead of requiring high-precision pump components, the system uses an adjustable piston stroke mechanism that can precisely control the conveying volume regardless of standard manufacturing tolerances, thereby achieving high volume accuracy with conventional manufacturing.
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 system reduces the risk of patient overfilling by precisely controlling the dialysis solution volume, even in the event of pump defects, enhancing safety and accuracy.
Implementation Method 1
By application of an overpressure in the chamber 4, the membrane 9, and with it the flexible film, is pressed into the pump chamber 3 of the cassette
Implementation Method 2
If in contrast a vacuum is applied to the chamber 4 in that the piston 8 is moved to the left, the membrane 9 is, however, pulled into the chamber 4
Implementation Method 3
Gravimetric devices can be used to generate the flow of dialysis solution, i.e. those in which the flow is effected by gravity
Data Source
AI summary
A pump system for generating a volume flow of a dialysis solution in a dialysis machine, the pump system includes at least one piston pump having a piston that cooperates with a working fluid, which exerts a force on a conveying means, and in particular on a membrane. The pump system includes setting means, with which a conveying volume of the at least one piston pump per piston stroke can be reduced, with the setting means having at least one of a position-variable mechanical piston stop to reduce the piston stroke, means to reduce a quantity of the working fluid, and means to reduce a volume of a conveying chamber that cooperates with the conveying means and that contains the dialysis solution to be conveyed.