Blood Pump Diaphragm Speed Control for Hemolysis Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing extracorporeal blood pumps, such as peristaltic pumps, cause hemolysis in patients' blood during hemodialysis, leading to reduced hematocrit levels and the need for erythropoietin treatment to regenerate red blood cells, which is particularly undesirable for patients with naturally low hematocrit levels or those undergoing treatments like end-stage renal failure.
Innovation Solution
A blood pump design featuring a cartridge with a flexible diaphragm that moves between maximum and minimum volumes, controlled by a pump driver to create pulsatile flow, which increases the disruption of the boundary layer in semi-permeable membranes, allowing larger waste molecules to pass through while minimizing red blood cell damage, and can operate in single or twin needle configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If peristaltic pumps are used for extracorporeal blood circulation, then reliability is improved, but hemolysis occurs causing reduced hematocrit levels
Solution Approach 1:
The patent replaces the mechanical peristaltic pumping system with a pneumatic system that uses a flexible diaphragm actuated by controlled gas pressure. This substitution eliminates the mechanical compression and shearing forces that cause hemolysis in peristaltic pumps, while maintaining reliable blood circulation through pressure-driven flow control.
Solution Approach 2:
The patent changes the fundamental operating parameters of the blood pump by using variable gas pressure control to achieve different flow rates and pulsatile patterns. By controlling the pressure differential across the diaphragm, the system can optimize blood flow characteristics to minimize hemolysis while maintaining therapeutic effectiveness.
2Productivity
If the flexible diaphragm moves at high speed to increase pulsatile flow, then waste removal efficiency is improved, but red blood cell damage increases
Solution Approach 1:
The patent employs periodic pulsatile flow generated by the reciprocating motion of the flexible diaphragm. By controlling the frequency and amplitude of these periodic cycles, the system enhances boundary layer disruption and waste removal efficiency while keeping individual pulse velocities within safe limits to prevent red blood cell damage.
Solution Approach 2:
The system dynamically adjusts diaphragm movement characteristics including speed, amplitude, and frequency based on treatment requirements. This dynamic control allows optimization of pulsatile flow for maximum waste removal while maintaining safe velocity thresholds to protect red blood cells from mechanical damage.
3Object-affected harmful factors
If the flexible diaphragm moves at low speed to minimize red blood cell damage, then hemolysis is reduced, but waste removal efficiency decreases
Solution Approach 1:
The periodic pulsatile action of the diaphragm creates repeated disruption of the boundary layer at the semi-permeable membrane interface. Even at lower speeds, this periodic disruption accumulates to achieve effective waste removal, allowing the system to maintain low hemolysis levels while preserving dialysis efficiency.
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 design minimizes red blood cell damage, enhances waste removal efficiency, and maintains optimal hematocrit levels by controlling the diaphragm's speed and flow rates, reducing the need for excessive erythropoietin administration and minimizing vascular damage during hemodialysis.
Implementation Method 1
An increase in speed of the flexible diaphragm of the first pump chamber between extremes of movement results in an increase in pulsatile flow of the patients blood
Implementation Method 2
Increasing pulsatile flow of the patients blood, i.e. by increasing the range of output flow rates from the pump, increases disruption of the boundary layer
Implementation Method 3
Waste materials of small molecular size pass through the membrane by means of diffusion
Data Source
Figure 1~2
Figure 3~4
AI summary
A blood pump comprising a cartridge, the cartridge comprising a first recess therein, said first recess having a surface, and a flexible diaphragm closing said first recess, the first recess and the flexible diaphragm defining a first pump chamber, said first pump chamber having an inlet and an outlet wherein the flexible diaphragm of the first pump chamber is movable between a first position, separated in use from the surface of the first recess, in which said first pump chamber has a maximum volume, and a second position, substantially adjacent to the surface of the first recess, in which said first pump chamber has a minimum volume a pump driver arranged to interface with the cartridge, said pump driver operable to move the flexible diaphragm of the first pump chamber in a first direction into said first recess to, in use, pump blood from the chamber and to move the flexible diaphragm of the first pump chamber in a second direction away from the first recess to, in use, draw blood into said first pump chamber, wherein the pump driver controls the movement of the flexible diaphragm of the first pump chamber such that the flexible diaphragm of the first pump chamber moves toward said first position at a first speed and moves toward said second position at a second speed, said second speed being greater than said first speed.