Autonomic Heart Rate Control for Extracorporeal Life Support
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Solution Overview
Problem
Current extracorporeal life support (ECLS) systems fail to account for the natural mammalian control system, leading to unstable control and the need for continuous human monitoring due to differences in individual patient responses and metabolic demands, which conventional 'set-point' control systems cannot replicate.
Innovation Solution
A control system that integrates with the autonomic nervous system by using heart rate as a surrogate to control blood flow rate and gas transfer rates, mimicking the natural control system and adjusting oxygen and carbon dioxide transfer rates to match metabolic demand without direct measurement of blood gas composition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If conventional set-point control systems are used to maintain fixed blood gas concentrations, then control stability is improved, but individual patient variability and changing metabolic demands cannot be accommodated
Solution Approach 1:
The control system delegates control authority to the patient's own autonomic nervous system by using heart rate (a natural physiological signal) as the control input. The system serves itself by leveraging the patient's inherent physiological regulation mechanisms rather than imposing external fixed set-points, thereby achieving both stability through physiological consistency and adaptability through natural response to metabolic demands.
Solution Approach 2:
The system changes the control parameter from fixed blood gas concentration set-points to a dynamically varying physiological parameter (heart rate) that naturally reflects metabolic demand. This parameter change allows the system to adapt to individual patient variability and changing conditions while maintaining control stability through the physiological consistency of heart rate responses.
2Device complexity
If fixed blood flow rate and gas flow rate are maintained through the oxygenator, then device complexity is reduced, but the system cannot respond to changing metabolic demands
Solution Approach 1:
The system introduces dynamics into the control by using heart rate as a varying input signal that naturally reflects changing metabolic demands. Instead of fixed rates, the blood flow rate and gas flow rate become dynamic variables that automatically adjust in response to physiological changes, achieving adaptability without complex control algorithms.
Solution Approach 2:
The system implements physiological feedback by using heart rate (a natural output of the autonomic nervous system responding to metabolic demand) as the input signal for controlling blood and gas flow rates. This feedback loop enables the system to respond to changing metabolic demands while maintaining relatively simple control logic based on a single physiological parameter.
3Productivity
If automated control systems process measured values to control blood and gas flow rates, then productivity is improved, but continuous human monitoring is still required to prevent dangerous conditions
Solution Approach 1:
The control system is fully self-regulating by using the patient's own heart rate as the control input, eliminating the need for external human monitoring. The system serves itself by leveraging physiological feedback mechanisms, achieving both high productivity through complete automation and high reliability by preventing dangerous conditions through natural physiological limits.
Solution Approach 2:
The system implements closed-loop feedback control where heart rate measurements automatically adjust blood and gas flow rates. This feedback mechanism provides both automation efficiency (no manual intervention needed) and safety reliability (continuous automatic adjustment prevents dangerous conditions) by linking control directly to physiological needs.
4Adaptability or versatility
If set-points are manually adjusted to maintain respiration within acceptable bounds, then adaptability to individual patients is improved, but the system requires continuous human intervention
Solution Approach 1:
The system eliminates the need for continuous human adjustment by making the control self-regulating through physiological feedback. The patient's own heart rate automatically determines the appropriate blood and gas flow rates, providing individual adaptability without requiring human intervention for each patient's unique needs.
Solution Approach 2:
The system changes from manual adjustment of fixed set-points to automatic adjustment based on dynamic physiological parameters (heart rate). This parameter change enables the system to adapt to individual patients automatically, eliminating the need for continuous human intervention while maintaining high adaptability.
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
Provides stable, portable, and adaptable ECLS systems that mimic natural lung function, reducing the need for continuous monitoring and enabling improved patient mobility and recovery rates.
Implementation Method 1
a sensor arranged to detect and output a measurand, wherein the measurand is characteristic of a single autonomic nervous system output
Implementation Method 2
a controller arranged to receive the measurand, and further arranged to control, according to the measurand: a blood flow rate through an extracorporeal life support device
Implementation Method 3
transfer of oxygen from the air flow to the blood flow and transfer of carbon dioxide from the blood flow to the air flow through the membrane material
Data Source
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AI summary
The present invention provides an extracorporeal life support device control system and method arranged to provide suitable gas and blood flow rates through an extracorporeal life support device. The control system comprises: a sensor arranged to detect and output a measurand, wherein the measurand is characteristic of a single autonomic nervous system output defining a metabolic demand; and a controller arranged to receive the measurand, and further arranged to control, according to the measurand: gas and/or liquid flow rates through an extracorporeal life support device; wherein the flow rates are arranged to provide blood gas concentrations similar to those arising from healthy lungs at the metabolic demand. In the case of patients with healthy lungs, the control system can control the blood flow rate without controlling gas flow rates through an oxygenator. The control system of the present invention aims to improve and to simplify control of blood gas compositions resulting from use of extracorporeal life support devices. It similarly aims to simplify control of blood pumps.