Electrosurgical RF Sealing with Impedance-Slope Energy Control
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Solution Overview
Problem
Existing electrosurgical instruments face challenges in delivering energy efficiently and effectively due to variability in tissue impedance, leading to inconsistent seal times, thermal damage, and inability to adapt energy output levels based on tissue type, resulting in less hemostatic seals and potential over- or under-delivery of energy.
Innovation Solution
The instrument employs tissue classification through impedance sensing and uses composite load curves to adjust energy delivery, incorporating a method for detecting the bathtub region exit and seal completeness without relying on fixed time thresholds, allowing for adaptive energy output based on tissue type and impedance changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a minimum time threshold is imposed to avoid premature detection of bathtub region exit, then reliability of seal detection is improved, but seal time increases and thermal damage increases
Solution Approach 1:
The control algorithm dynamically adjusts the minimum time threshold based on real-time tissue impedance monitoring. Instead of using a fixed time threshold, the system continuously evaluates impedance characteristics and adapts the threshold accordingly, allowing the seal detection to be both reliable and time-efficient. This dynamic approach enables the system to exit the bathtub region promptly when conditions are met, reducing unnecessary seal time and thermal damage while maintaining detection reliability.
2Device complexity
If a fixed impedance threshold is used to determine seal completion, then device complexity is reduced, but manufacturing precision of seal quality deteriorates due to tissue variability
Solution Approach 1:
The control algorithm incorporates multiple impedance parameters and their rates of change rather than relying on a single fixed impedance threshold. By monitoring impedance magnitude, impedance slope, and impedance acceleration, the system creates a multi-dimensional assessment of seal completion. This approach maintains relatively simple device architecture while significantly improving seal quality precision by accounting for tissue variability through multiple dynamic parameters.
3Device complexity
If the same power output is used for all tissue types, then device complexity is reduced, but adaptability to different tissue types deteriorates
Solution Approach 1:
The system applies local quality by tailoring energy delivery parameters to the specific tissue type being sealed. Through real-time impedance analysis, the control algorithm identifies tissue characteristics and adjusts power output, pulse duration, and energy delivery pattern accordingly. This allows each tissue type to receive optimized energy parameters for optimal sealing, achieving high adaptability without requiring multiple specialized devices or overly complex system architecture.
4Speed
If impedance threshold is set low for quick detection, then speed of seal cycle termination is improved, but seal quality deteriorates due to under-delivery of energy
Solution Approach 1:
The control algorithm transitions from single-dimension impedance threshold detection to multi-dimensional assessment by incorporating impedance magnitude, impedance rate of change (slope), and impedance acceleration. This dimensional expansion allows the system to quickly detect seal completion through rapid impedance changes while simultaneously verifying that adequate energy has been delivered by assessing the overall impedance trajectory. The multi-dimensional approach enables both fast termination and high seal quality by providing richer information about the sealing process state.
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 enhances the precision and efficiency of tissue sealing by ensuring optimal energy delivery, reducing thermal damage, and achieving consistent hemostatic seals by adapting to different tissue types.
Implementation Method 1
deliver radiofrequency (RF) energy to the tissue
Implementation Method 2
radio frequency (RF) energy to tissue (e.g., to coagulate or seal the tissue)
Implementation Method 3
monitor an impedance of the tissue
Data Source
AI summary
A surgical system includes electrodes configured to deliver radiofrequency energy to tissue, and a processor configured to control delivery of the RF energy with increasing power, monitor tissue impedance, calculate tissue impedance slope, compare the tissue impedance to a predetermined impedance threshold, and compare the tissue impedance slope to a predetermined impedance slope threshold. The processor is configured to, in response to determining that the tissue impedance is not greater than the predetermined impedance threshold or that the tissue impedance slope is not greater than the predetermined impedance slope threshold, control the delivery of the RF energy to continue with increasing power. The processor is also configured to, in response to determining that the tissue impedance is greater than the predetermined impedance threshold and that the tissue impedance slope is greater than the predetermined impedance slope threshold, control the delivery of the RF energy with a predetermined constant voltage.