Electrotome output energy control method and system based on tissue impedance slope change

Abstract

The invention relates to a method for judging the impedance change trend through a high-frequency electrotome, and belongs to the field of medical instruments. The method comprises the following steps: detecting the initial impedance of the biological tissue at the end part of the electrotome and judging the tissue type based on the initial impedance; in the energy output process, tissue impedance is detected at the set frequency, and the current impedance change slope is calculated; judging the overall trend of the current impedance change, and selecting a corresponding target slope value based on the tissue type and the trend; comparing the current impedance change slope with a target slope value to obtain a slope deviation; adjusting the output power of the electrotome based on the slope deviation; and repeating the steps until the blood coagulation of the tissue is completed. The tissue impedance change slope is monitored in real time, the output energy of the electrotome is dynamically adjusted, the electrotome can adapt to the characteristics of different tissues, excessive heating or insufficient energy is avoided, the consistency of the coagulation effect is improved, and tissue thermal damage and surgical risks are reduced.

Description

Technical Field

[0001] This invention relates to the field of medical devices, specifically to a method and system for controlling the output energy of an electrosurgical unit based on changes in tissue impedance slope. Background Technology

[0002] High-frequency electrosurgical units are crucial devices in surgical procedures for cutting and coagulation. Currently, there are two main energy control methods: one is constant current, constant power, or constant voltage mode, which is simple to control but does not consider tissue differences, easily leading to inconsistent sealing effects; the other is polynomial curve control based on time parameters, which, while having some adjustment capability, still cannot adapt to the dynamic changes in different tissues under energy application. Both existing energy control methods carry the risk of thermal damage or incomplete coagulation. Summary of the Invention

[0003] To address the problems in the prior art, this invention proposes a method and system for controlling the output energy of an electrosurgical unit based on changes in tissue impedance slope.

[0004] The technical solution adopted in this invention is as follows: On the one hand, this invention proposes a method for controlling the output energy of an electrosurgical unit based on changes in tissue impedance slope, comprising the following steps: S1: Detect the initial impedance of biological tissue at the tip of the electrosurgical unit, and determine the type of tissue based on the magnitude of the initial impedance; S2: During energy output, the impedance of the tissue is detected at a set frequency, and the current impedance change slope is calculated; S3: Determine the overall trend of the current impedance change, and select the corresponding target slope value based on the tissue type and the trend; S4: Compare the current impedance change slope with the target slope value to obtain the slope deviation; S5: Adjust the output power of the electrosurgical unit based on the slope deviation.

[0005] Preferably, before energy output, the slope of the dissociation drag reduction stage for different tissue types is pre-set. and the slope of the drying resistance stage The target slope value is the slope of the dissociation drag reduction stage under the corresponding tissue type. Or the slope of the drying resistance stage Setting slope parameters for different tissue types and different stages of impedance change allows for more tissue-specific energy control, improving the targeting and accuracy of the coagulation process. Preferably, the slope of the dissociation drag reduction stage and the slope of the drying resistance stage The parameters were pre-set by performing cutting and coagulation experiments on different types of tissues and fitting and analyzing the impedance data during the dissociation resistance reduction and drying resistance increase phases. Scientific experimentation improves the scientific validity and reliability of the slope setting, making it more closely aligned with actual surgical procedures.

[0006] Preferably, the tissue type is determined by comparing the initial impedance with the initial impedance of different tissue types in the experimental database, which can quickly and automatically identify the tissue type and provide a basis for the selection of the subsequent slope target value.

[0007] Preferably, in step S2, the calculation of the current impedance change slope The expression is: in Indicates the detection time interval. This represents the impedance detected at the current moment. This represents the impedance detected at the previous moment. The purpose of this step is to achieve real-time quantification of impedance changes, providing an accurate data basis for subsequent control.

[0008] Preferably, in step S3, determining the overall trend of the current impedance change specifically involves applying the Mann-Kendall test to the impedance detection data over a recent period. The advantage of this method is that it can accurately identify the trend direction even when the data fluctuates significantly, and it can also determine the significance of the trend, thereby improving the anti-interference capability.

[0009] Preferably, in step S4, the output power of the electric knife is adjusted based on the slope deviation using an incremental PID algorithm to achieve smooth and stable power adjustment and avoid sudden output changes.

[0010] Preferably, step S4 specifically includes: calculating the power adjustment amount based on the slope deviation, wherein the calculation expression for the power adjustment amount ΔP(t) is: in This is the proportionality coefficient. The integral coefficient is... These are the differential coefficients. The slope deviation at the current moment. This represents the slope deviation from the previous moment. The slope deviation at the previous time step; The output power at the previous moment Plus power regulation The output power P(t) of the electrosurgical unit at the current moment is obtained.

[0011] This step achieves more precise energy control through an incremental PID algorithm, adapting to the dynamic changes in tissue impedance during high-frequency electrosurgical operation.

[0012] On the other hand, the present invention also proposes an electrosurgical output energy control system based on tissue impedance slope variation to implement the above-mentioned method.

[0013] This invention monitors the slope of tissue impedance changes in real time and dynamically adjusts the output energy of the electrosurgical unit, which can adapt to the characteristics of different tissues, avoid overheating or insufficient energy, improve the consistency of coagulation effect, and reduce tissue thermal damage and surgical risks. Attached Figure Description

[0014] Figure 1 This is a flowchart of the electrosurgical output energy control method of the present invention; Figure 2 This is the theoretical temperature-impedance characteristic curve of biological tissue; Figure 3 This involves monitoring and calculating the actual impedance change of biological tissues when they are subjected to energy output. Detailed Implementation

[0015] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0016] like Figure 1 As shown, an electrosurgical unit output energy control method based on tissue impedance slope variation includes the following steps: Step 1: Set the slope of the dissociation drag reduction stage for different tissue types and the slope of the drying resistance stage ; Step 2: At the start of the electrosurgical energy output, detect the initial impedance of the biological tissue at the tip of the electrosurgical unit, and determine the type of tissue based on the magnitude of the initial impedance; Step 3: During the continuous energy output of the electrosurgical unit, the impedance of the biological tissue at the tip of the electrosurgical unit is detected at a certain frequency; based on the detected impedance data, the current impedance change slope is calculated. ; Step 4: Based on the impedance data obtained from the test, determine whether the overall trend of impedance change over a recent period is upward or downward; combining the tissue type and the current trend, select the corresponding slope for the dissociation and resistance reduction stage. Or the slope of the drying resistance stage As the target value of slope ; Step 5: Calculate the current impedance change slope. With slope target value Compare the slopes and calculate the deviation. Step 6: Adjust the output power of the electrosurgical unit using an incremental PID algorithm based on the current slope deviation; Step 7: Repeat steps 3 through 6 until tissue clotting is complete.

[0017] The following section will elaborate on each step.

[0018] For step one, the slope of impedance change is set for different tissue types and different stages of impedance change.

[0019] During the process of applying energy to biological tissue by electrosurgical unit, the change pattern of tissue impedance is as follows: Figure 2 As shown, the process includes a dissociation-induced resistance reduction stage and a drying-induced resistance increase stage. In the dissociation-induced resistance reduction stage, the tissue temperature increases with the continuous application of energy. The tissue contains free ions (Na⁺, K⁺, Cl⁻, etc.). The increase in temperature promotes dissociation and ion migration, and the tissue impedance gradually decreases. With continued application of energy, the tissue temperature rises, causing tissue water to evaporate. The space for free ions to move is reduced, and the ion migration rate is significantly lower. Although the ion concentration seems to increase due to the reduction in water, the tissue is close to a dehydrated state, with only a small amount of bound water remaining. Ions can hardly migrate freely, and the tissue impedance increases at this time. This process is the drying-induced resistance increase stage.

[0020] In practical applications, when energy is applied to tissue, the tissue temperature rises, water movement intensifies and bubbles may form, and due to detection errors, tissue impedance changes exhibit significant fluctuations. Figure 3 As shown, this leads to errors in judging the impedance change trend using the ordinary difference method.

[0021] Furthermore, when using an electrocautery knife to coagulate blood vessels, vessels can be classified into different types based on their diameter, wall thickness, and composition. Each vessel has a different initial impedance, and the impedance after coagulation also varies. In this embodiment, the electrocautery knife is only used for coagulating vascular tissue, but similarly, other tissues can also be classified into different types.

[0022] Therefore, a preset impedance value cannot be simply used as the target for the output energy of the electrosurgical unit. This invention sets a target value based on the slope of the impedance change. For the dissociation resistance reduction stage and the drying resistance increase stage, this invention sets the slope for the dissociation resistance reduction stage respectively. and the slope of the drying resistance stage Two sets of parameters. For different types of blood vessels, actual tissue cutting and coagulation experiments need to be performed separately. The experimental data should be statistically analyzed, and the impedance data of the dissociation drag reduction stage and the drying drag increase stage should be fitted to determine the slope of the dissociation drag reduction stage for different types of vessels. and the slope of the drying resistance stage .

[0023] For step two, at the initial time point of the electrosurgical energy output, the initial impedance of the biological tissue at the electrosurgical tip is detected, and the tissue type is determined based on the magnitude of the initial impedance. In this embodiment, the tissue impedance is calculated by detecting the voltage and current of the electrosurgical energy output. The impedance measured at the initial time point of the electrosurgical energy output is the initial impedance. The initial impedance of the currently treated tissue is compared with the initial impedance of different types of tissue in the tissue cutting and coagulation experiment to determine the tissue type.

[0024] For step three, during the continuous energy output of the electrosurgical unit, the impedance of the biological tissue at the tip of the electrosurgical unit is detected at a certain frequency; based on the detected impedance data, the current impedance change slope is calculated. .

[0025] In this embodiment, the tissue impedance is calculated by detecting the voltage and current of the energy output from the electrosurgical unit. Impedance change slope The calculation expression is: in Indicates the detection time interval. This represents the impedance detected at the current moment. This represents the impedance obtained in the previous test.

[0026] For step four, based on the impedance data obtained from the detection, determine whether the overall trend of impedance changes over a recent period is upward or downward; and, considering the tissue type and the current trend, select the corresponding slope for the dissociation and resistance reduction stage. Or the slope of the drying resistance stage As the target value of slope .

[0027] Because the actual changes in tissue impedance obtained from testing can fluctuate considerably, such as Figure 3 As shown, this requires judging the impedance change trend from the fluctuating data in order to determine the slope setting value.

[0028] Conventional statistical methods can be used to determine the trend of impedance changes, including trend line fitting, cumulative growth, and Mann-Kendall test.

[0029] Specifically, the trendline fitting method involves using a linear regression model. Impedance data obtained over a recent period are fitted, where t represents the time series, y represents the fitted impedance, and a and b are fitting parameters. After fitting, the impedance change trend is determined using the fitting parameter b. Indicates an increase, Indicates a decrease. This indicates a stable state. The duration of the most recent period can be set to 100ms.

[0030] The cumulative growth method specifically involves calculating the cumulative growth from the impedance data at the energy output starting point to each time point. The growth rate reflects the cumulative effect of the overall trend. A growth rate greater than 0 indicates an increase; a growth rate less than 0 indicates a decrease; and a growth rate equal to 0 indicates stability.

[0031] The Mann-Kendall test (MK test) works as follows: A sign statistic S is calculated from impedance data obtained within a recent period; a standardized statistic Z is then calculated based on the sign statistic S. The Z value directly reflects the direction of the trend and statistical significance. Indicates an increase, Indicates a decrease. Indicates stability. The larger the value, the more pronounced the trend. The duration of the most recent period can be set to 100ms.

[0032] After obtaining the current trend of tissue type and impedance, if the trend is upward or stable, select the corresponding slope for the drying resistance increase stage. As the target value of slope If the trend is downward, select the corresponding slope for the dissociation and drag reduction stage. As the target value of slope .

[0033] For step five, the current impedance change slope With slope target value Compare the slopes and calculate the slope deviation. The calculation expression is: For step six, adjust the output power of the electrosurgical unit according to the current slope deviation.

[0034] Generally, incremental PID control can be used. The relationship between the power deviation and the slope deviation that need to be adjusted is as follows: in, For the power deviation that needs to be adjusted, This is the proportionality coefficient. The integral coefficient is... These are the differential coefficients. The slope deviation at the current moment. This represents the slope deviation from the previous moment. This represents the slope deviation at the previous time step.

[0035] The current output power of the electrosurgical unit is adjusted as follows: in, The output power at the current moment. This represents the output power at the previous moment.

[0036] For step seven, repeat steps three through six until tissue clotting is deemed complete. The determination of complete tissue clotting is based on the detection of tissue impedance returning to a set value. It should be noted that the numbering of steps three through six is ​​not a mandatory execution order in this invention and can be adjusted according to actual needs.

[0037] Based on the above-mentioned method for controlling the output energy of an electrosurgical unit based on changes in tissue impedance slope, this embodiment also proposes a control system for the output energy of an electrosurgical unit based on changes in tissue impedance slope, including a high-frequency electrosurgical unit and a cutting head connected to the unit; the high-frequency electrosurgical unit includes: Impedance detection module is used to detect the impedance of biological tissue at the blade tip at a set frequency during energy output; The data processing module is used to calculate the initial impedance, the current impedance change slope, and determine the overall trend of impedance change based on the detected impedance data. The power control module is used to adjust the output power of the high-frequency electrosurgical unit according to the output of the data processing module.

[0038] The data processing module pre-stores the slope of the dissociation resistance reduction stage and the slope of the drying resistance increase stage corresponding to different tissue types. It can determine the tissue type based on the initial impedance, select the corresponding target slope value based on the impedance change trend, and calculate the slope deviation. The power control module adjusts the output power in real time based on the slope deviation.

[0039] This invention, by real-time monitoring of the slope of tissue impedance changes and dynamically adjusting the output energy of the electrosurgical unit, can adapt to the characteristics of different tissues, avoid overheating or insufficient energy, improve the consistency of coagulation effects, and reduce tissue thermal damage and surgical risks. This method has high practicality and adaptability and can be widely applied to various high-frequency electrosurgical devices, improving surgical safety and operational efficiency.

[0040] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for controlling output energy of an electrosurgical instrument based on changes in tissue impedance slope, comprising: determining a tissue impedance slope; and adjusting the output energy of the electrosurgical instrument based on the determined tissue impedance slope. The method comprises the following steps: S1: detecting the initial impedance of the biological tissue at the end of the electrotome, and judging the type of the tissue according to the size of the initial impedance; S2: detecting the impedance of the tissue at a set frequency during energy output, and calculating the current impedance change slope; S3: judging the overall trend of the current impedance change, and selecting a corresponding target slope value based on the type of the tissue and the trend; S4: comparing the current impedance change slope with the target slope value to obtain a slope deviation; S5: adjusting the output power of the electrotome based on the slope deviation.

2. The method of claim 1, wherein, Before the energy output, the dissociation drop phase slope under different tissue types is also preset and the dry up phase slope , the target slope value is the dissociation drop phase slope under the corresponding tissue type or the dry up phase slope .

3. The method of claim 2, wherein, The slope of the dissociation decrease phase and the slope of the dry increase phase are preset by cutting clotting experiments on different types of tissue and fitting analysis of the impedance data of the dissociation decrease phase and the dry increase phase in the experiments.

4. The method of claim 1, wherein, The type of the tissue is judged according to the size of the initial impedance by comparing the initial impedance of the tissue with the initial impedance of different types of tissues in an experimental database.

5. The method of claim 1, wherein, In step S2, the current impedance change slope is calculated The expression for the current impedance change slope is: wherein denotes a detection time interval, denotes an impedance detected at a current time point, denotes an impedance detected at a previous time point.

6. The method of claim 1, wherein, In step S3, the overall trend of the current impedance change is specifically judged by using the Mann-Kendall test method on the impedance detection data in the recent period of time.

7. The method of claim 1, wherein, In step S4, the output power of the electrotome is specifically adjusted based on the slope deviation by using an incremental PID algorithm.

8. The method of claim 6, wherein, The step S4 specifically comprises: calculating a power adjustment amount based on the slope deviation, and a calculation expression of the power adjustment amount ΔP(t) is: wherein is a proportional coefficient, is an integral coefficient, is a derivative coefficient, is a slope deviation at a current time, is a slope deviation at a previous time, is a slope deviation at a time before the previous time. The output power at the previous moment Plus power regulation The output power P(t) of the electrosurgical unit at the current moment is obtained.

9. A tissue impedance slope change based electrosurgical output energy control system for implementing the method of claim 1, characterized by, The high-frequency electrotome comprises a main machine and a tool head connected with the main machine. The high-frequency electrotome main machine comprises: an impedance detection module for detecting the impedance of the biological tissue at the tool head at a set frequency during energy output; a data processing module for calculating the initial impedance, the current impedance change slope, and judging the overall trend of the impedance change according to the detected impedance data; a power control module for adjusting the output power of the high-frequency electrotome main machine according to the output of the data processing module.

10. The system of claim 9, wherein, The data processing module pre-stores the dissociation impedance reduction stage slope and the drying impedance increase stage slope corresponding to different types of tissues, can judge the type of the tissue according to the initial impedance, select a corresponding target slope value according to the impedance change trend, and calculate the slope deviation; and the power control module adjusts the output power in real time according to the slope deviation.

Images