Closed-loop blood flow control in extracorporeal oxygenation
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Solution Overview
Problem
Current blood flow control mechanisms in extracorporeal perfusion systems lack precision in restricting blood flow rates, often requiring manual clamping of flexible tubes, which is inefficient and cannot accurately maintain a pre-determined flow rate, especially during the final stages of extracorporeal perfusion when transitioning heart and lung functionality back to the patient.
Innovation Solution
A closed-loop control system comprising a flow sensor and an adjustable restriction, such as a motorized clamp, that monitors and adjusts the blood flow rate in real-time to maintain it below a user-defined threshold, ensuring accurate and controlled blood flow management in venous lines, allowing for better control of blood circulation and perfusion support during the end phases of extracorporeal perfusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If manual clamping of flexible tubes is used to restrict blood flow rate, then the flow rate can be reduced, but the precision and accuracy of maintaining a pre-determined flow rate cannot be achieved
Solution Approach 1:
The patent replaces the manual mechanical clamping system with an automated motorized clamp actuated by a drive mechanism. This substitution enables precise flow rate control through motorized adjustment of the clamp position and force, eliminating the imprecision of manual operation while maintaining ease of use through automated control.
Solution Approach 2:
The patent implements a feedback control system using a flow sensor to continuously monitor the actual blood flow rate and compare it with the target flow rate. The controller adjusts the motorized clamp position based on this feedback to maintain the desired flow rate, thereby achieving high precision flow control that was impossible with manual clamping alone.
2Measurement precision
If a flow sensor and adjustable restriction are used to maintain precise flow rate, then flow control accuracy is improved, but the system complexity increases
Solution Approach 1:
The patent integrates multiple functions into a unified control system where the flow sensor, controller, and motorized clamp work together as a single automated flow control unit. This multi-functional integration achieves precise flow measurement and control while managing system complexity through coordinated operation of components rather than separate independent systems.
Solution Approach 2:
The control system is designed to automatically regulate blood flow rate without continuous manual intervention. The flow sensor continuously monitors flow conditions, the controller processes this information and autonomously adjusts the motorized clamp to maintain the target flow rate, enabling the system to self-regulate and reducing the need for complex external control mechanisms.
3Reliability
If manual clamping is used to restrict blood flow, then the flow rate can be reduced, but the ability to maintain a minimum flow rate and prevent complete cessation of flow is compromised
Solution Approach 1:
The flow sensor provides continuous feedback on the actual blood flow rate, enabling the controller to detect when flow approaches the minimum threshold. This feedback mechanism ensures the motorized clamp is adjusted to maintain flow above the critical minimum level, preventing complete cessation of blood flow while maintaining precise control over the flow rate.
Solution Approach 2:
The control system is configured with predetermined minimum flow rate thresholds that trigger preventive actions. Before flow can be reduced to dangerous levels, the system automatically adjusts the motorized clamp to maintain flow above the threshold, thereby preventing the harmful effect of complete flow cessation before it can occur.
Data Source
AI summary
A control system in a blood line (12) of a cardiopulmonary bypass perfusion system (1) comprises a flow sensor (26) to determine a flow value indicative of the flow rate, a controller configured to process the flow value, and an adjustable restriction (28) responsive to the controller, to reduce the flow rate in the venous blood line (12) to maintain a flow rate to the venous blood reservoir that does not exceed a restriction threshold. As the adjustable restriction (28) is responsive to the flow sensor (26), this provides a closed loop control mechanism that avoids restricting the blood line (12) of the perfusion system (1) more than intended.