Multipart Fluid System for Regional Citrate Anticoagulation
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Solution Overview
Problem
Current CRRT systems face challenges in maintaining appropriate calcium levels during citrate anticoagulation, as the removal of calcium through the semipermeable membrane can lead to dangerously low ionized calcium levels, requiring separate calcium infusion, which is delicate and potentially fatal if not managed correctly.
Innovation Solution
A multipart fluid system comprising an anticoagulation fluid with at least 8 mM citrate and a dialysis or infusion fluid with 2-8 mM citrate and 1-5 mM total calcium, allowing for regional citrate anticoagulation in an extracorporeal blood circuit without the need for separate calcium infusion, by controlling citrate levels to prevent coagulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If citrate anticoagulation is used in CRRT, then coagulation in the extracorporeal blood circuit is prevented, but ionized calcium levels drop to dangerously low levels
Solution Approach 1:
The patent applies local quality by creating a regional anticoagulation environment only in the extracorporeal circuit through pre-filter citrate infusion, while maintaining normal calcium levels in the patient's systemic circulation. This localized approach allows citrate to prevent clotting in the circuit without causing harmful hypocalcemia in the patient's body.
Solution Approach 2:
The patent uses citrate as an intermediary substance that temporarily binds calcium in the extracorporeal circuit to prevent coagulation, then allows calcium to be restored after the circuit. The citrate acts as a temporary mediator that facilitates safe blood circulation through the circuit without permanently depleting calcium levels.
2Object-affected harmful factors
If separate calcium infusion is administered to replace removed calcium, then ionized calcium levels are maintained, but the system complexity and risk of fatal errors increase
Solution Approach 1:
The patent merges the anticoagulation function and calcium management into a single integrated system. By infusing citrate only in the pre-filter region and relying on post-filter calcium diffusion and metabolic clearance, the system combines multiple functions (anticoagulation, calcium preservation, and waste removal) without requiring a separate calcium infusion apparatus.
Solution Approach 2:
The system enables self-service by allowing the dialysis fluid to automatically replenish calcium levels through diffusion across the membrane and by utilizing the patient's own metabolic capacity to clear citrate and restore calcium homeostasis, eliminating the need for external calcium infusion intervention.
3Reliability
If calcium-free dialysis fluid is used with citrate anticoagulation, then coagulation is prevented, but significant calcium removal occurs requiring replacement
Solution Approach 1:
The patent segments the dialysis process into pre-filter and post-filter regions with different fluid compositions. The pre-filter region receives citrate-containing anticoagulation fluid, while the post-filter region receives calcium-containing dialysis fluid. This segmentation allows calcium removal in the pre-filter to be compensated by calcium replenishment in the post-filter region.
Solution Approach 2:
The patent applies preliminary action by infusing citrate before the filter to establish anticoagulation, then allowing calcium to be replenished after the filter. This sequential approach ensures coagulation prevention occurs first, followed by calcium restoration, avoiding the need for simultaneous calcium replacement during active anticoagulation.
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 system effectively reduces or prevents calcium removal during dialysis without increasing the risk of clotting, maintaining stable ionized calcium levels and avoiding the need for separate calcium infusion, thus ensuring patient safety.
Implementation Method 1
Citrate acts as an anticoagulant by lowering the ionized calcium concentration within the plasma, through calcium citrate complex formation
Implementation Method 2
the waste substances and excess fluid are transferred by diffusion through the semipermeable membrane wall into a dialysis fluid flowing on the dialysate side
Implementation Method 3
a portion of the plasma liquid is removed from the blood by means of convective flow through the semipermeable membrane
Implementation Method 4
Citrate that exists in the blood is rapidly metabolized in the liver, forming three bicarbonate ions per citrate ion. As the citrate concentration is lowered in the metabolism, citrate complex bound calcium is released and returns to ionized calcium
Data Source
AI summary
A method of treating blood withdrawn from patient including: simultaneously withdrawing blood and infusing withdrawn blood from and to the patient by flowing the withdrawn blood through an extracorporeal dialysis circuit including a dialyzer having a semi-permeable dialysis membrane and a dialysate side adjacent the membrane; feeding a dialysate containing 1 to 5 mM total calcium and 2 to 8 mM citrate to the dialysate side of the dialyzer, and introducing an anticoagulation fluid including at least 8 mM citrate into the withdrawn blood upstream of the dialyzer.