Blood Circuit Temperature Modeling for Remote Core Sensing
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Solution Overview
Problem
Existing extracorporeal blood treatment systems face challenges in accurately measuring and controlling patient core temperature due to heat transfer variations in the blood circuit, particularly when temperature sensors are located remotely from the patient, leading to inaccuracies in temperature readings.
Innovation Solution
A method that involves measuring blood temperature at different flow rates and using thermal models to calculate the core temperature, incorporating heat transfer coefficients and ambient temperature estimation, allowing for recursive calculations to refine the inlet temperature estimation and correct for heat exchange biases in the blood circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If temperature sensors are located remotely from the patient in the blood circuit, then the system can measure blood temperature, but the temperature readings become inaccurate due to heat transfer variations in the blood circuit
Solution Approach 1:
The system changes the flow rate parameter of blood through the circuit to create different thermal conditions. By measuring temperature at multiple flow rates and using thermal models to calculate heat transfer coefficients, the system can compensate for heat exchange between blood and environment, thereby improving temperature measurement accuracy despite remote sensor placement
Solution Approach 2:
The system uses feedback by measuring temperature at multiple flow rates and using this information to calculate heat transfer coefficients. This feedback loop allows the system to correct for heat exchange effects and determine accurate blood temperature even when sensors are located remotely in the blood circuit
2Measurement precision
If temperature sensors are placed close to the patient, then temperature readings are more accurate, but the system cannot account for heat transfer dynamics in the blood circuit
Solution Approach 1:
The system varies the flow rate parameter and measures temperature responses to calculate heat transfer coefficients. This allows the system to model and compensate for heat exchange dynamics, improving core temperature estimation accuracy while maintaining operational simplicity through automated calculations
Solution Approach 2:
The system performs preliminary measurements at multiple flow rates to calculate heat transfer coefficients before determining the final core temperature. This preliminary action of characterizing heat transfer dynamics enables more accurate temperature control during actual treatment operations
3Measurement precision
If multiple flow rate measurements are taken to calculate heat transfer coefficients, then temperature measurement accuracy improves, but the measurement time increases
Solution Approach 1:
The system uses periodic flow rate changes to gather temperature data at multiple flow rates. By systematically varying flow rates and measuring temperature responses, the system can calculate heat transfer coefficients and improve inlet temperature accuracy through structured periodic measurements
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 enables accurate estimation of patient core temperature, even with remote temperature sensing, by accounting for heat transfer dynamics, thus improving temperature control and detection of abnormal conditions during treatments.
Implementation Method 1
heat transfer between the blood and the external environment of the blood circuit
Implementation Method 2
heat gain or loss caused by heat transfer between the blood and the external environment
Implementation Method 3
calculating the heat lost up to the point where the temperature is measured
Implementation Method 4
the heat transfer properties of the tube are known (that is the internal and external heat transfer coefficient, tube conductivity)
Data Source
AI summary
A core temperature measurement may be made by varying the heat transfer dynamics of a blood circuit and fitting parameters of a blood circuit heat transfer configuration to measurements under the varied conditions. Then the input temperature of the patient core can be extracted from the model and a current temperature measurement remote from the patient core and optionally other measurements such as blood flow rate.