Thermodilution Injectate Delivery System with Real-Time Flow Feedback
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Solution Overview
Problem
The variability in injectate volume and injection technique during thermodilution procedures leads to inaccuracies in cardiac output measurements, as users may apply different forces and volumes, affecting the precision of thermodilution parameters like cardiac output, global end diastolic volume, and extra vascular lung water.
Innovation Solution
An injectate delivery system with real-time feedback and flow measurement devices, such as pressure differential sensors and temperature sensors, calculates the injectate volume using the Stewart-Hamilton equation, ensuring accurate cardiac output determination by minimizing user error and variability in injection technique.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If users manually inject the bolus at different rates and forces, then the procedure is simple and quick, but the injectate volume and temperature vary considerably, causing loss of accuracy and precision in cardiac output measurement
Solution Approach 1:
The system incorporates real-time feedback through sensors that monitor injectate flow rate, volume, and temperature during injection. The feedback signal is provided to the user to guide proper injection technique, ensuring consistent and accurate deliveries that maintain measurement precision while allowing flexible injection speeds.
Solution Approach 2:
The patent replaces manual mechanical injection control with an automated or semi-automated injection system that uses sensors and control mechanisms to regulate injectate delivery. This substitution eliminates user variability in injection force and rate while maintaining the simplicity of the procedure through automated control.
2Speed
If users apply extreme force to inject the bolus as quickly as possible, then the injection speed increases, but the actual injectate volume and temperature may differ from expected values, reducing measurement accuracy
Solution Approach 1:
Real-time feedback sensors monitor the actual injectate volume and flow rate during injection, providing continuous information to the user or control system. This ensures that even at high injection speeds, the actual volume delivered matches the expected volume, maintaining precision while allowing rapid injection.
Solution Approach 2:
The injection system is designed to self-regulate and self-monitor, with sensors automatically detecting and reporting injectate parameters. The system serves itself by providing real-time data without requiring external intervention, ensuring consistent volume delivery regardless of injection speed.
3Measurement precision
If the injectate delivery system includes real-time feedback and flow measurement devices, then the measurement accuracy and precision improve, but the device complexity increases
Solution Approach 1:
The system integrates multiple functions into a single unified platform, where the same sensor suite serves both flow measurement, volume calculation, and temperature monitoring purposes. This multi-functionality reduces the need for separate dedicated devices, thereby limiting the increase in overall system complexity while maintaining high measurement precision.
Solution Approach 2:
The patent combines flow measurement devices, temperature sensors, and feedback mechanisms into an integrated injectate delivery system. By merging these components into a single coordinated system rather than separate devices, the overall complexity is minimized while achieving accurate and precise thermodilution 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
The system provides accurate and precise measurements of cardiac output and other thermodilution parameters by ensuring consistent injectate volume and flow rate, reducing errors associated with user variability and improving the reliability of transpulmonary thermodilution results.
Implementation Method 1
A flow measurement device may be provided in line with the tubing from the syringe outlet. The flow measurement device may have known flow characteristics and flow area that provide a relationship between pressure loss and velocity of the injectate, such that when the pressure loss is known, the velocity may be determined.
Implementation Method 2
A temperature sensor may be provided in line with and preferably downstream of the flow measurement device.
Implementation Method 3
A normal curve characteristically shows a sharp upstroke from rapid injection of the injectate. This is followed by a smooth curve and slightly prolonged downslope back to the baseline. Since this curve is representing a change from warmer temperature to cooler and then back to warmer temperature
Data Source
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AI summary
Apparatus and methods for the measurement, control, or both, of thermodilution injectate flow for calculation of transpulmonary thermodilution parameters. An injectate delivery system includes a syringe for holding an injectate and a conduit configured at one end to be connected to a catheter. A flow measurement device is interposed in the conduit to generate a signal for determining the flow rate of the fluid from the syringe to the catheter. A processor receives the signal from the flow measurement device and calculates the injectate volume to be used as input for calculating a transpulmonary thermodilution parameter such as cardiac output. A GUI is provided to direct a user on whether the injection rate is too fast or too slow. Rather than measuring or calculating flow rate, a system may include a constant flow valve to provide a constant flow rate from the syringe.