Hemodialysis Flow Restriction Control for Sudden Blood Pressure Changes
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Solution Overview
Problem
Existing hemodialysis devices fail to address sudden pressure changes in the blood circuit, such as kinks, which can lead to unstable fluid replacement due to excessive dialysate flow into the blood circuit.
Innovation Solution
A hemodialysis device with feedback control mechanisms for flow rate restriction devices, utilizing pressure measurement and adjustment of flow rates through first and second flow rate restriction devices to stabilize fluid replacement, even in the presence of sudden pressure changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a replacement fluid passage is provided between the dialysate circuit and blood circuit for fluid replacement, then fluid replacement function is achieved, but the system becomes vulnerable to sudden pressure changes in the blood circuit causing excessive dialysate flow
Solution Approach 1:
The control device performs feedback control by repeatedly adjusting the second flow rate restriction device based on measured pressures at the connection portion and in the blood circuit, plus the target replacement fluid flow rate. This closed-loop feedback mechanism detects pressure changes and automatically compensates by adjusting the flow restriction, preventing excessive dialysate flow while maintaining stable fluid replacement.
Solution Approach 2:
The system dynamically changes the flow rate restriction parameter by adjusting the second flow rate restriction device during operation. The control device modifies the restriction level in response to measured pressure variations, transforming a static flow control system into a dynamic one that adapts to changing conditions to maintain stable replacement fluid flow.
2Speed
If feedback control is performed by adjusting the second flow rate restriction device multiple times during one round, then replacement fluid flow rate is quickly stabilized, but control complexity increases
Solution Approach 1:
The control device implements repeated feedback control within one round (from filling to discharging the supply compartment). By continuously measuring pressures and adjusting the second flow rate restriction device multiple times during this cycle, the system achieves rapid stabilization of replacement fluid flow rate in response to pressure changes, overcoming the limitation of single-adjustment systems.
Solution Approach 2:
The control device performs periodic adjustments of the flow rate restriction device during each round of the dialysate supply cycle. This periodic control action, synchronized with the dialysate supply rhythm, enables the system to respond to pressure changes at multiple intervals within one round, achieving quick stabilization without requiring continuous complex intervention.
Data Source
AI summary
A hemodialysis device including a replacement fluid passage between a dialysate circuit and a blood circuit, the dialysate circuit and the replacement fluid passage being respectively provided with first and second flow rate restriction devices. Also provided is a connection portion pressure sensor for measuring a pressure of a connection portion between a dialysate supply passage and the replacement fluid passage, and a vein-side pressure sensor for measuring a pressure of the blood circuit. A control device adjusts an opening degree of the second flow rate restriction device multiple times based on the measured pressure of the connection portion pressure sensor, and the measured pressure of the vein-side pressure sensor, for one round, being from when a supply compartment of a chamber provided to the dialysate circuit is filled with a fresh dialysate until all of the fresh dialysate in the supply compartment has been discharged.