Electrosurgical Generator Impedance Trajectory Control
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Solution Overview
Problem
Current electrosurgical systems face challenges in precisely controlling energy delivery to achieve effective tissue sealing, as they lack precise control over mechanical parameters like pressure and electrode gap distance, and do not adequately account for tissue impedance variations during the sealing process.
Innovation Solution
An electrosurgical system that includes impedance sensing circuitry, a processor to determine tissue reaction, and a controller to generate a target impedance trajectory, adjusting energy output to match the desired impedance values and ensuring a predetermined minimum time period, while also considering temperature and fluid sensing for optimal sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If electrosurgical energy is applied to tissue to achieve sealing, then tissue sealing is achieved, but precise control of energy delivery is difficult due to lack of control over mechanical parameters and tissue impedance variations
Solution Approach 1:
The system continuously monitors tissue impedance during electrosurgical energy delivery and uses this feedback to dynamically adjust energy output. The controller compares measured impedance values against target impedance trajectory and modifies energy delivery in real-time to maintain optimal sealing conditions, resolving the contradiction by enabling precise control through closed-loop feedback without requiring complex mechanical parameter control
Solution Approach 2:
The system changes the electrical parameter (impedance) as the primary control variable for tissue sealing. By monitoring impedance variations and adjusting energy delivery based on impedance trajectory, the system achieves precise tissue sealing control without needing to control mechanical parameters like pressure and gap distance, thereby simplifying the overall device complexity while improving sealing quality
2Measurement precision
If tissue impedance is monitored and energy delivery is adjusted to match target impedance trajectory, then precise energy control is achieved, but the system requires complex sensing and control circuitry
Solution Approach 1:
The electrosurgical generator performs multiple functions using the same basic circuitry: it generates electrosurgical energy, measures tissue impedance, and controls energy delivery based on impedance feedback. This multi-functionality approach achieves precise impedance measurement and control without requiring separate dedicated sensing and control systems, thereby reducing overall device complexity while maintaining high measurement precision
Solution Approach 2:
The system uses the tissue's own electrical properties (impedance) as both the control variable and the measurement parameter. The tissue impedance naturally changes during the sealing process, providing self-indicating information about sealing progress without requiring external sensors or complex measurement systems. This self-service approach achieves precise measurement with minimal additional circuitry
3Reliability
If the electrosurgical system waits for a predetermined minimum time period to ensure proper sealing, then sealing reliability is improved, but the procedure time increases
Solution Approach 1:
The system uses real-time impedance monitoring to detect when tissue sealing is complete based on reaching the target impedance trajectory, eliminating the need for fixed waiting periods. The controller continuously monitors impedance and can immediately terminate energy delivery when sealing criteria are met, ensuring reliability through objective measurement while minimizing procedure time by avoiding unnecessary delays
Solution Approach 2:
The system pre-establishes a target impedance trajectory that defines the complete sealing process parameters including the minimum time period. By planning the entire sealing trajectory in advance with predetermined impedance targets and time parameters, the system optimizes both reliability and efficiency, ensuring adequate sealing time is spent at critical phases while minimizing total procedure time through efficient trajectory management
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 ensures precise control of energy delivery, achieving consistent and effective tissue sealing by matching tissue impedance to a target trajectory, thereby improving the quality and reliability of vessel sealing.
Implementation Method 1
sensing circuitry configured to measure impedance of tissue
Implementation Method 2
application of high radio frequency electrical current to a surgical site to cut, ablate, or coagulate tissue
Implementation Method 3
tissue reaction corresponds to a boiling point of tissue fluid
Data Source
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AI summary
An electrosurgical generator is disclosed. The generator includes an RF output stage configured to supply electrosurgical energy to tissue via at least one active electrode configured to apply electrosurgical energy to tissue; sensing circuitry configured to measure impedance of tissue; and a controller. The controller is configured to determine whether a tissue reaction has occurred as a function of a minimum impedance value and a predetermined rise in impedance, wherein tissue reaction corresponds to a boiling point of tissue fluid; generate a target impedance trajectory as a function of measured impedance and desired rate of change based on the tissue reaction determination, wherein the target impedance trajectory includes a plurality of target impedance values; and drive tissue impedance along the target impedance trajectory by adjusting the output level of the electrosurgical generator to substantially match tissue impedance to a corresponding target impedance value for at least a predetermined minimum time period.