Feed-Forward Citrate Anticoagulation Control for Extracorporeal Blood Treatment
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Solution Overview
Problem
Conventional systems for citrate anticoagulation during extracorporeal blood treatment are complex, costly, and lack flexibility in controlling calcium levels, relying on multiple sensors and feedback mechanisms that are inaccurate and user-unfriendly, making it difficult to adjust treatment parameters during the process.
Innovation Solution
A feed-forward control mechanism is used to determine the time periods for citrate and calcium addition, allowing for flexible adjustment by healthcare professionals, eliminating the need for complex sensors by activating citrate addition at the beginning of treatment and calcium addition after the initial filtration period, with both continued during and after treatment to ensure adequate calcium replenishment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If conventional feedback control systems with multiple sensors are used to monitor and adjust calcium levels, then automated control of blood calcium levels is achieved, but the system becomes complex, expensive, and less flexible for user adjustment
Solution Approach 1:
The patent extracts the calcium level monitoring function from complex sensor systems and replaces it with a simplified feed-forward control mechanism that calculates calcium requirements based on treatment parameters (blood flow rate, treatment time, citrate dose) without requiring continuous sensor feedback. This eliminates multiple sensors and complex control algorithms while maintaining automated control.
Solution Approach 2:
The system performs preliminary calculation of calcium requirements before treatment begins and during treatment based on predetermined formulas using treatment parameters. This feed-forward approach determines calcium addition rates in advance rather than relying on continuous feedback measurement, simplifying the system architecture.
2Measurement precision
If multiple sensors and sophisticated control algorithms are implemented to accurately monitor blood calcium levels, then automated adjustment of citrate and calcium addition rates is possible, but manufacturing costs increase and the system becomes less user-friendly
Solution Approach 1:
The patent removes the need for expensive calcium concentration sensors by extracting the monitoring function and replacing it with mathematical calculations based on treatment parameters. The system calculates expected calcium removal based on blood flow rate, treatment duration, and dialyzer characteristics, then adds calcium accordingly without requiring actual concentration measurements.
Solution Approach 2:
The invention replaces expensive, complex sensor systems with simple, inexpensive calculation algorithms that use readily available treatment parameters. This substitution dramatically reduces manufacturing costs while maintaining functional equivalence in terms of calcium level control.
3Extent of automation
If feedback control mechanisms are used to maintain predetermined calcium concentrations, then automated control is achieved, but flexibility for doctors to adjust settings during treatment is reduced
Solution Approach 1:
The system implements dynamic adjustability where doctors can modify treatment parameters (blood flow rate, treatment time, citrate dosage) during treatment, and the feed-forward control algorithm automatically recalculates calcium requirements in real-time based on these changes. This maintains automated control while providing full flexibility for clinical adaptation.
Solution Approach 2:
The patent enables parameter changes during treatment by allowing doctors to adjust treatment settings, with the control system automatically updating calcium addition rates based on the new parameters using the feed-forward calculation methodology. This maintains both automation and clinical flexibility.
4Reliability
If citrate is added to prevent coagulation during extracorporeal blood treatment, then anticoagulation effect is achieved, but calcium is bound and removed from the blood requiring replenishment
Solution Approach 1:
The system performs preliminary calculation of calcium requirements based on the anticipated citrate dosage and treatment parameters before and during treatment. By calculating the expected calcium binding effect of citrate in advance, the system can proactively add calcium to maintain blood calcium levels without waiting for deficiency to occur.
Solution Approach 2:
The patent implements a calculated feedback mechanism where the control system continuously monitors treatment parameters (citrate rate, blood flow rate, treatment time) and automatically adjusts calcium addition rates based on these inputs using predetermined formulas, maintaining calcium homeostasis without requiring direct calcium concentration measurement.
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 reduces manufacturing costs, enhances user control over calcium levels, and allows for flexible adjustments during treatment, ensuring accurate calcium replenishment without the need for elaborate sensor systems.
Implementation Method 1
The added citrate prevents coagulation of blood by binding ionized calcium present in the extracorporeal blood flow within the tubing/filter of the extracorporeal blood treatment machine
Implementation Method 2
As the citrate-treated blood reaches the haemodialyzer (filter), the citrate and with it the bound calcium is removed from the extracorporeal blood flow
Data Source
AI summary
A system for extracorporeal blood treatment is disclosed that includes a haemofiltration device, a pump for pumping blood through the haemofiltration device, citrate means upstream to add citrate, calcium means downstream to add calcium solution, and a control configured to activate or inactivate the citrate addition means and/or the calcium addition means, wherein the control activates the citrate addition means at the beginning of blood treatment and for a first time period filters the blood with activated citrate addition means and continues to operate the citrate addition means until the end of blood treatment activates the calcium addition means after the first time period has elapsed when the total extracorporeal blood volume in the system has been filtered and citrate treated, continues to operate the calcium addition means in an active state during blood treatment to stably maintain a user-determined calcium addition rate, and continues to operate the calcium addition means in an active state after the end of blood treatment, until a second time period has elapsed after the end of treatment. A method of controlling such a system to ensure adequate calcium replenishment after citrate anticoagulation is also disclosed.