Recursive Filter Tissue Impedance Control for Electrosurgery
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Solution Overview
Problem
Existing electrosurgical technologies face challenges in precisely controlling energy application to tissue to achieve desired surgical effects without causing unwanted charring or collateral damage, as they rely on manual adjustments of power, waveform, and impedance measurements which can be inefficient and prone to thermal spread.
Innovation Solution
A method and system utilizing recursive filters to process tissue impedance data, transitioning between energy states based on averaged values and predetermined thresholds, allowing for real-time adjustment of energy application to maintain optimal tissue conductance and minimize tissue damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If manual adjustments of power and waveform are used to control energy application, then ease of operation is maintained, but manufacturing precision of energy delivery is insufficient leading to tissue damage
Solution Approach 1:
The system continuously measures tissue impedance and uses this feedback to automatically adjust power delivery. The controller compares measured impedance against expected values and modifies energy application in real-time, replacing manual adjustments with closed-loop control that achieves precise energy delivery without requiring complex manual coordination.
Solution Approach 2:
The system performs self-adjustment of power and waveform parameters based on automatic impedance measurements. The controller autonomously modifies energy delivery parameters without surgeon intervention, allowing the system to self-optimize energy application for precise tissue effect while minimizing collateral damage.
2Productivity
If high power is applied to achieve desired surgical effect, then productivity is improved, but object-affected harmful factors increase causing thermal spread and collateral damage
Solution Approach 1:
The system applies energy in controlled pulses rather than continuous high power, using periodic duty cycles that allow tissue to cool between energy bursts. This pulsed delivery maintains surgical effectiveness while reducing cumulative thermal accumulation and preventing collateral thermal damage to surrounding structures.
Solution Approach 2:
The system dynamically adjusts power levels in real-time based on measured tissue impedance changes. As tissue properties change during surgery, the controller automatically modifies energy delivery parameters to maintain optimal effectiveness while preventing excessive power application that would cause thermal spread and collateral damage.
3Manufacturing precision
If impedance measurement is used to regulate power, then manufacturing precision of energy delivery is improved, but measurement precision requirements increase the difficulty of detecting and measuring
Solution Approach 1:
The system uses the existing electrosurgical circuitry to perform dual functions: delivering therapeutic energy and measuring tissue impedance. The same electrodes and circuit paths used for energy delivery are utilized for impedance measurement, eliminating the need for separate measurement hardware and simplifying the overall system while achieving precise energy control.
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 precise control of energy delivery, reducing tissue damage and improving surgical outcomes by maintaining peak tissue conductance and minimizing thermal spread, thus enhancing the effectiveness and safety of electrosurgical procedures.
Implementation Method 1
High frequency electrical energy, e.g., radio frequency (RF) energy, is produced by the electrosurgical generator and applied to the tissue by the electrosurgical tool
Implementation Method 2
measuring the electrical impedance and change thereof across the tissue at the surgical site provides a good indication of the state of desiccation or drying of the tissue
Data Source
Figure 1A~2
Figure 3
Figure 4A
AI summary
A method for controlling energy applied to tissue in two or more states as a function of a detected tissue property is provided. The method includes the steps of: determining an initial value of the detected tissue property, recursively processing the detected tissue property to obtain an averaged value thereof, updating the recursively processing step with the initial value of the detected tissue property and transitioning between two or more states based on a comparison of averaged values obtained by two or more recursive filters.