Surgical Device Tissue Parameter Estimation
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Solution Overview
Problem
Current surgical devices lack the ability to accurately estimate tissue mass and thermal resistance, leading to inefficient energy delivery during procedures like electrosurgery, which can result in overcooking or undercooking of tissues.
Innovation Solution
The method involves generating a test signal to estimate tissue impedance and temperature changes, using microprocessors or specialized circuits to calculate tissue mass and thermal coefficients, allowing for precise control of energy delivery based on these parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional surgical devices are used without tissue parameter estimation, then the device structure remains simple, but the energy delivery precision deteriorates leading to overcooking or undercooking of tissues
Solution Approach 1:
The system performs preliminary measurement of tissue impedance before energy delivery to estimate tissue parameters such as mass and thermal resistance. This preliminary action enables the control system to predict tissue response and adjust energy delivery parameters in advance, achieving precise temperature control without requiring complex real-time monitoring during energy delivery.
Solution Approach 2:
The patent replaces direct mechanical or thermal measurement methods with electrical impedance measurement. By measuring tissue impedance changes during electrosurgery, the system indirectly estimates tissue parameters through established relationships between impedance and tissue properties, avoiding the need for complex physical sensors or invasive measurement devices.
2Reliability
If fixed energy delivery is used without tissue parameter consideration, then the control system remains simple, but the treatment effectiveness deteriorates due to overcooking or undercooking
Solution Approach 1:
The system implements feedback control by continuously monitoring tissue impedance during energy delivery and using this information to adjust power delivery in real-time. The control system compares actual impedance measurements with predicted values and modifies energy delivery parameters to maintain target temperature, ensuring reliable treatment outcomes while adapting to varying tissue characteristics.
Solution Approach 2:
The system dynamically changes energy delivery parameters (power level, pulse duration, frequency) based on estimated tissue parameters. By adjusting these parameters according to tissue mass and thermal resistance estimates, the system optimizes heating efficiency and achieves consistent treatment effectiveness across different tissue types and sizes without requiring complex mechanical adjustments.
3Productivity
If tissue mass and thermal resistance are not estimated, then the measurement process remains simple, but the energy delivery efficiency deteriorates
Solution Approach 1:
The patent employs electrical impedance measurement as a substitute for direct thermal or mass measurement methods. By measuring impedance changes that occur during tissue heating, the system estimates tissue mass and thermal resistance parameters, enabling efficient energy delivery optimization without requiring complex physical measurement instruments or invasive procedures.
Solution Approach 2:
The system uses tissue impedance as an intermediary parameter to infer tissue mass and thermal resistance properties. Instead of directly measuring these difficult-to-obtain parameters, the system measures impedance changes during energy delivery and uses established physiological relationships to estimate the target parameters, achieving efficient energy delivery optimization through indirect measurement.
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 more accurate control of tissue temperature and energy delivery, improving the efficiency and effectiveness of surgical procedures by ensuring appropriate energy levels are applied based on tissue characteristics.
Implementation Method 1
The tissue's impedance converts the electrical energy (also referred to as electrosurgical energy) associated with the AC into heat, which causes the tissue temperature to rise.
Implementation Method 2
sensing voltage and current waveforms of the test signal, calculating an impedance of the tissue and a change in the tissue impedance based on the sensed voltage and current waveforms
Data Source
AI summary
Systems and methods for estimating tissue parameters, including mass of tissue to be treated and a thermal resistance scale factor between the tissue and an electrode of an energy delivery device, are disclosed. The method includes sensing tissue temperatures, estimating a mass of the tissue and a thermal resistance scale factor between the tissue and an electrode, and controlling an electrosurgical generator based on the estimated mass and the estimated thermal resistance scale factor. The method may be performed iteratively and non-iteratively. The iterative method may employ a gradient descent algorithm that iteratively adds a derivative step to the estimates of the mass and thermal resistance scale factor until a condition is met. The non-iterative method includes selecting maximum and minimum temperature differences and estimating the mass and the thermal resistance scale factor based on a predetermined reduction point from the maximum temperature difference to the minimum temperature difference.