Temperature-Compensated Fluid Balance Control in Dialysis Circuits
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Solution Overview
Problem
In medical blood treatment, such as dialysis, precise fluid balance is crucial for patient safety, but existing accounting devices struggle to accurately account for fluid volumes due to temperature-dependent volume changes and density variations, leading to potential errors in fluid balance calculations.
Innovation Solution
A method and device that measure and correct fluid balance by using flow sensors and temperature sensors to calculate a corrected volume flow, accounting for temperature differences between sections of the fluid circuit, and adjust pumping rates to maintain accurate fluid balance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If temperature-dependent volume changes are not corrected, then the device complexity is reduced, but the measurement precision of fluid balance deteriorates
Solution Approach 1:
The system continuously measures temperature at multiple points in the fluid circuit and uses this feedback to dynamically correct volume flow measurements. The controller adjusts the corrected volume flow based on real-time temperature data, ensuring accurate fluid balance monitoring despite temperature variations in the dialysis circuit.
Solution Approach 2:
The system changes the measurement parameter from simple volumetric flow to temperature-compensated flow by incorporating temperature as a correction parameter. The volume flow measurement is adjusted based on measured temperature values and predetermined temperature coefficients, transforming the raw measurement into a corrected value that accounts for thermal expansion effects.
2Reliability
If temperature correction is applied to volume flow measurements, then the reliability of fluid balance calculation is improved, but the device complexity increases
Solution Approach 1:
The system performs preliminary temperature measurements at strategic points in the fluid circuit before the final balance calculation. By measuring temperature upstream and downstream of the blood pump and heat exchanger in advance, the system prepares correction factors that are then applied to the volume flow measurements, ensuring reliable fluid balance calculation without adding complex real-time computation requirements.
Solution Approach 2:
The system introduces temperature as an intermediary parameter that mediates between the physical volume flow and the corrected fluid balance calculation. Temperature sensors act as intermediaries that detect thermal conditions, and the controller uses these intermediate temperature readings to calculate correction factors, bridging the gap between raw volumetric measurements and accurate fluid balance determination.
3Measurement precision
If multiple temperature measurements are taken in the fluid circuit, then the measurement precision of volume flow correction is improved, but the device complexity increases
Solution Approach 1:
The fluid circuit is segmented into distinct thermal zones, with temperature measurements taken at representative points in each segment. Temperature sensors are placed upstream and downstream of the blood pump and heat exchanger, dividing the circuit into manageable sections. This segmentation allows targeted temperature correction for each zone without requiring continuous temperature monitoring throughout the entire circuit.
Solution Approach 2:
The system applies local temperature correction by measuring temperature at specific locations where thermal effects are most significant, such as near the heat exchanger and blood pump. Rather than uniformly correcting all measurements, the system applies localized correction factors based on local temperature conditions at each measurement point, improving precision while minimizing the number of sensors required.
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 significantly reduces temperature-dependent errors, ensuring precise fluid balance and reducing the risk of fluid mismanagement during treatments, enhancing patient safety by minimizing unnoticed fluid withdrawals.
Implementation Method 1
The flow sensor is designed and/or arranged to measure at least one volume flow in at least one first and/or in one second section of the fluid circuit
Implementation Method 2
The functional device further comprises at least one device for detecting a temperature in the first and second sections and/or a temperature difference between the first and second sections of the fluid circuit
Implementation Method 3
Accurate monitoring of these fluid volumes administered to and removed from the patient is of particular importance for the patient's safety and health... temperature-dependent volume changes and density variations
Data Source
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AI summary
The invention relates to a method for determining a fluid balance (FB) between at least a first volumetric flow (F1) of a first portion (A1) of a fluid circuit (1) of a medical function device (17) and at least a second volumetric flow (F2) of a second portion (A2) of the fluid circuit (1) of the medical function device (17) and/or for controlling and/or regulating at least one volumetric flow (F1, F2, UF) of a portion of the fluid circuit (1) of the medical function device (17) and comprises at least the following steps: adjusting or detecting at least a first volumetric flow (F1) in at least a first portion (A1) of the fluid circuit (1); adjusting, accepting or detecting at least a first temperature (T1) in at least a first portion (A1) of the fluid circuit (1) and detecting at least a second temperature (T2) in at least a second portion (A2) of the fluid circuit (1) or detecting at least a temperature difference (DT) between the first and the second portion (A2) of the fluid circuit (1); detecting at least a second volumetric flow (F2) in at least a second portion (A2) of the fluid circuit (1); and forming a fluid balance (FB) from at least the first volumetric flow (F1) and a corrected value of the second volumetric flow (F2_corr), wherein the corrected value (F2_corr) is determined and/or calculated at least from the detected second volumetric flow (F2) and the second temperature (T2) and/or the temperature difference (DT).