Implantable LVAD Pump Speed Control Under Power Constraints
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Solution Overview
Problem
Implantable blood pumps face challenges in managing their speed effectively when power is constrained, due to factors like low internal battery power, misalignment of transcutaneous energy transfer (TETS) coils, thrombus, or transient power demands.
Innovation Solution
The method involves starting the blood pump at a programmed set speed and decreasing it to a minimum set speed if battery capacity is low or TETS power is unavailable. The speed is progressively adjusted based on available power, attempting to increase or decrease the speed as power conditions change.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the pump operates at a high programmed set speed, then blood flow performance is improved, but power consumption increases and may exceed available power from the internal battery or TETS
Solution Approach 1:
The pump speed is made dynamic rather than fixed, allowing it to adjust between minimum set speed and programmed set speed based on real-time power availability. The control system continuously monitors power conditions and modifies the operating speed accordingly, transforming the static speed parameter into a dynamic one that adapts to changing power constraints.
Solution Approach 2:
The operating parameters of the pump, specifically the speed, are changed based on power availability conditions. The system transitions between different speed states (minimum set speed vs. programmed set speed) by detecting power constraints and adjusting the speed parameter accordingly, allowing the pump to operate within available power limits while maintaining optimal performance when possible.
2Use of energy by moving object
If the pump speed is decreased to conserve power, then energy efficiency is improved, but blood flow performance deteriorates
Solution Approach 1:
The system applies partial action by operating the pump at a minimum set speed rather than the full programmed set speed when power is constrained. This partial operation maintains essential blood flow functionality while consuming less power, accepting reduced performance as a necessary compromise under power-limited conditions rather than complete shutdown.
Solution Approach 2:
The pump speed dynamically adjusts between minimum and programmed set speeds based on power availability, allowing the system to optimize the trade-off between energy efficiency and blood flow performance in real-time rather than being locked into a fixed operating point.
3Duration of action of moving object
If the pump operates at minimum set speed with low battery capacity, then power consumption is reduced to extend battery life, but the risk of pump shutdown increases when power becomes insufficient
Solution Approach 1:
The system takes preliminary action by decreasing the pump speed to the minimum set speed in advance when power constraints are detected (low battery capacity or insufficient TETS power). This proactive speed reduction conserves power before complete depletion occurs, extending battery life and preventing abrupt shutdowns by preparing the system for power-limited operation ahead of time.
Solution Approach 2:
The minimum set speed acts as a cushioning mechanism that provides a safety margin between full operational speed and complete shutdown. By operating at this reduced speed under power-constrained conditions, the system creates a buffer that maintains pump operation longer than would be possible at full speed, cushioning against the risk of abrupt failure.
4Adaptability or versatility
If the pump speed is progressively adjusted based on power availability, then adaptability to power constraints is improved, but control system complexity increases
Solution Approach 1:
The speed control is segmented into discrete levels (minimum set speed and programmed set speed) rather than continuous adjustment. This segmentation simplifies the control logic by defining specific threshold-based states and transitions between them, making the adaptive control system more manageable and less complex while still providing effective adaptation to power constraints.
Solution Approach 2:
The system changes the speed parameter based on detected power conditions, implementing adaptability through parameter modification rather than complex control algorithms. By monitoring power availability and adjusting the speed parameter between two defined states, the system achieves adaptability with relatively simple control logic.
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 ensures that the blood pump operates efficiently by adjusting its speed according to available power, maintaining sufficient blood flow while conserving energy, and preventing pump shutdown due to power constraints.
Implementation Method 1
transcutaneous energy transfer system (TETS)... internal coil of the TETS... external coil of the TETS, the external coil being further in communication with a power source
Data Source
AI summary
A method of managing a speed of implantable blood pump. The implantable blood pump is in communication with an internal battery and a transcutaneous energy transfer system (TETS). The method includes starting the pump at a programmed set speed. The speed of the pump is decreased from the programmed set speed to a minimum set speed if either a capacity of the internal battery is less than a predetermined reserve level and TETS power is unavailable, or there is insufficient TETS power to maintain the programmed set speed. The speed of the pump is progressively decreased from the programmed set speed if there is insufficient power to maintain the programmed set speed.