A method and system for judging tissue coagulation state of high-frequency electrotome

Abstract

The application provides a tissue coagulation state judgment method and system for a high-frequency electrotome, and relates to the technical field of high-frequency electrotomes.The method comprises the following steps: initializing operation parameters;collecting the voltage and current between two electrodes of the high-frequency electrotome in real time, and calculating the real-time impedance of the tissue between the two electrodes to form an impedance sequence in the latest period of time;performing Mann-Kendall trend test on the impedance sequence to obtain a standardized statistic quantity;judging the change trend of the tissue impedance based on the standardized statistic quantity, and determining the tissue coagulation state according to the change trend.The Mann-Kendall trend test based on data statistics is adopted, the descending and ascending trends of the tissue impedance and the significant degree of the trends can be effectively judged, and the accuracy and reliability of the tissue coagulation state judgment are improved.

Description

Technical Field

[0001] This invention relates to the field of high-frequency electrosurgical technology, and specifically to a method and system for determining the coagulation state of tissues using high-frequency electrosurgical techniques. Background Technology

[0002] Bipolar high-frequency electrosurgical units are key instruments in minimally invasive surgery. Their working principle involves using high-frequency current between bipolar electrodes to heat local tissue, thereby denaturing proteins and sealing blood vessels. Accurately determining the coagulation state during the coagulation process is crucial for ensuring surgical success. Currently, most systems rely on the surgeon's visual observation or simple threshold methods. Visual observation relies on the surgeon's experience, while impedance threshold methods presuppose a fixed impedance value or rate of impedance change as a coagulation standard. However, in actual operation, tissue impedance values ​​exhibit significant fluctuations rather than an ideally smooth curve, which severely affects the accuracy of coagulation state assessment. Summary of the Invention

[0003] To address the problems in the prior art, this invention proposes a method and system for determining the coagulation state of tissues using high-frequency electrosurgical units.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for determining the coagulation state of tissue using high-frequency electrosurgical excision, comprising the following steps: S1: Initialize runtime parameters; S2: Real-time acquisition of voltage and current between the two electrodes of the high-frequency electrosurgical unit, and calculation of the real-time impedance of the tissue between the two electrodes to form an impedance sequence over a recent period of time; S3: Perform the Mann-Kendall trend test on the impedance sequence to obtain standardized statistics; S4: Determine the trend of tissue impedance change based on the standardized statistics, and determine the tissue coagulation state based on the trend.

[0005] Preferably, the initialization parameters include sampling frequency, sample size, and significance level. The values ​​of these parameters can be adjusted according to different tissue types and actual needs, laying the foundation for subsequent processing.

[0006] Preferably, in step S2, calculating the real-time impedance of the tissue between the two electrodes includes: calculating the phase angle φ between the voltage signal and the current signal, and applying the formula... Calculate the real-time impedance of the tissue between the two electrodes. This step obtains an impedance value that reflects the true characteristics of the tissue by compensating for phase angle errors.

[0007] Preferably, in step S2, the impedance sequence over the most recent period is formed by storing real-time impedance data in chronological order into a first-in-first-out data buffer. The size of the data buffer is equal to the sample size, ensuring that the data in the impedance sequence is impedance data over the most recent period.

[0008] Preferably, in step S3, performing the Man-Kendall trend test on the impedance sequence includes: calculating the sign statistic S and variance Var(S) of the impedance sequence, and calculating the standardized statistic Z based on the sign statistic S and variance Var(S). This step employs the Man-Kendall trend test to enhance the robustness and accuracy of the method, taking into account the large fluctuations in tissue impedance data.

[0009] Preferably, in step S4, determining the trend of tissue impedance based on the standardized statistic includes: calculating a given significance level. Critical value of standard normal distribution under the following conditions The absolute value of the standardized statistic Z is compared with the critical value. If the standardized statistic Z is greater than the critical value... This indicates a significant upward trend in tissue impedance; if the standardized statistic Z is less than the critical value... If the negative of the standardized statistic Z is less than the critical value, it is considered that there is a significant downward trend; if the absolute value of the standardized statistic Z is less than the critical value... If the impedance shows no significant trend, it is determined that the current impedance has no significant trend. This step reduces misjudgments caused by random fluctuations through statistical significance testing.

[0010] Preferably, determining the tissue coagulation state based on the changing trend includes: if there is a significant upward trend in tissue impedance, comparing the standardized statistic Z with a preset threshold; if the standardized statistic Z is greater than the preset threshold, the tissue is determined to be coagulated; otherwise, the tissue is determined to be uncoagulated. This step further improves the accuracy of tissue coagulation state determination by introducing a quantified threshold to perform secondary screening of the intensity of the significant trend.

[0011] On the other hand, the present invention proposes a tissue coagulation state judgment system to implement the above-mentioned tissue coagulation state judgment method.

[0012] This invention introduces a Mann-Kendall trend test that is not required to determine the data distribution and is insensitive to outliers. It enables effective judgment of the decreasing and increasing trends of tissue impedance and can calculate the significance. Even if the collected impedance data does not meet the normal distribution assumption, or if the collected resistance values ​​contain outliers and noise, the judgment results still have strong robustness and accuracy. Therefore, this invention achieves a more accurate and reliable judgment of tissue clotting. Attached Figure Description

[0013] Figure 1This refers to the theoretical temperature-impedance characteristic curve of biological tissue. Figure 2 This represents the actual change in impedance of biological tissue when subjected to energy output. Figure 3 This is an impedance model of the tissue between the two electrodes of a high-frequency electrosurgical unit. Detailed Implementation

[0014] 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.

[0015] Example 1 Tissues contain free ions (Na⁺, K⁺, Cl⁻, etc.). Increased temperature promotes dissociation and ion migration, leading to a decrease in tissue impedance; this process is called the dissociation-induced impedance reduction stage. As tissue temperature continues to rise, the increased temperature causes tissue water evaporation, reducing the space for free ions to move and significantly lowering ion migration rates. Although the ion concentration may appear to increase due to reduced water, the tissue is nearing a dehydrated state, with only a small amount of bound water remaining. Ions can hardly migrate freely, and at this point, the tissue impedance increases; this process is called the drying-induced impedance stage. Theoretically, the trend of tissue impedance change is as follows: Figure 1 For the process of using bipolar electrosurgical unit to solidify tissue, the solidification is completed during the drying and inhibition stage. The solidified tissues also differ in type, thickness, main components, etc., and the degree of increase in impedance at the completion of solidification varies for different tissues.

[0016] In practical applications, the impedance variation trend of the tissue is as follows: Figure 2 The host outputs energy to the tissue, and the tissue temperature gradually rises. During this process, water movement is intense, which may cause vaporization. Additionally, due to detection errors, the tissue impedance fluctuates significantly. To determine whether tissue coagulation has occurred based on unstable tissue impedance changes, this invention proposes a method for determining the coagulation state of tissue using high-frequency electrosurgical units. This embodiment details the specific implementation process of the method, including the following steps: Step 1: Initialize runtime parameters.

[0017] The operating parameters include, but are not limited to: the sampling frequency f of impedance data, the sample size n for trend judgment, and the significance level α for trend significance testing.

[0018] When the operator activates the high-frequency electrosurgical unit and applies energy to the biological tissue, steps two through five are repeated. The system's signal acquisition module begins to acquire the voltage signal U and current signal I output from the high-frequency generator to the tissue in real time at preset sampling intervals.

[0019] Step 2: Impedance data acquisition.

[0020] The current I and voltage U between the two electrodes of the high-frequency electrosurgical unit are collected at a preset sampling frequency.

[0021] To obtain accurate tissue impedance values, an electrical model needs to be established. Tissues contain free ions (Na⁺, K⁺, Cl⁻, etc.), and their impedance characteristics can be derived from the extracellular fluid resistance. Intracellular fluid resistance and cell membrane capacitance The equivalent circuit model representation is as follows: Figure 3 As shown. Therefore, the tissue impedance Z can be expressed as: This model shows that tissue impedance exhibits capacitive characteristics, rather than being purely resistive, resulting in a phase angle φ between voltage and current. To accurately reflect the true state changes of tissue under energy influence, phase compensation is necessary. Therefore, the phase angle φ between voltage U and current I also needs to be calculated. The real-time impedance value R of the tissue at the current moment is calculated by the following formula. The calculated real-time impedance values ​​R are stored sequentially in a first-in, first-out (FIFO) data buffer. The size of this buffer is the same as the preset sample size, thus forming a real-time updated impedance sequence of length n. .

[0022] Step 3: Mann-Kendall trend test (MK test).

[0023] The Mann-Kendall trend test is applied to the impedance sequence within the buffer. Specifically, the impedance sequence is calculated. The sign statistic S is calculated using the following formula: in, Let i and j be the impedance values ​​within the buffer, and sign be the sign function. If, then it is recorded as 1; if If the two numbers are equal, then it is recorded as -1; if they are equal, then it is recorded as zero.

[0024] After calculating the sign statistic S, the variance of the sign statistic under the no-trend assumption is further calculated. Furthermore, considering the possibility of repeated values ​​(junction values) in the impedance sequence, the variance needs to be corrected. The calculation formula is Where n is the sample size and m is the number of result groups. is the number of values ​​in the p-th group.

[0025] When all impedance data in an impedance sequence are unequal, the sequence has no junction value, and a correction term is required. ,at this time Simplified to: .

[0026] When there are end values, equal observations can lead to a large number of... This makes the actual fluctuation of S smaller than when there are no knots. The purpose of the correction term is to subtract the reduction in variation due to knots from the original variance, ensuring... The calculations are more accurate.

[0027] Further calculate the standardized statistic Z. When When S approximately follows a normal distribution, Z is defined as: The standardized statistic Z is the standardized result of the signed statistic S in the MK test. It transforms the signed statistic S into a value that follows a standard normal distribution, thus allowing for a quick determination of trend significance through the critical value of the normal distribution. The sign and magnitude of the Z value directly reflect the direction of the trend and its statistical significance.

[0028] Step 4: Trend Judgment.

[0029] Calculate the critical value of the standard normal distribution at a given significance level α. The absolute value of the Z value obtained in step three is compared with the critical value. The comparison is performed where the significance level α is a positive number. If the absolute value of the standardized statistic Z is greater than or equal to the critical value... If the tissue impedance shows a significant trend, then it is determined that there is a significant trend in tissue impedance; specifically, if the standardized statistic Z is greater than the critical value... If the tissue impedance shows a significant upward trend, it indicates that the tissue has entered the drying resistance-increasing stage; if the standardized statistic Z is less than the critical value... The negative value of the standardization statistic Z indicates a significant downward trend, suggesting the organization is still in the dissociation and drag-reduction phase. If the absolute value of Z is less than the critical value... If the current impedance shows no significant trend, it indicates that the tissue is in a transitional phase between the drying resistance-increasing phase and the dissociation resistance-decreasing phase.

[0030] If the tissue impedance shows a significant upward trend, the magnitude of this upward trend is used to determine whether the tissue has coagulated. Specifically, the standardized statistic Z can be compared with a preset threshold. If the standardized statistic Z is greater than the preset threshold, the tissue is considered to have coagulated; otherwise, it is considered not to have coagulated and energy needs to be applied further. Alternatively, the impedance data can be fitted, and the slope of the fitted curve at the current time point can be calculated. The slope is then compared with a preset threshold. If the slope is greater than the preset threshold, the tissue is considered to have coagulated; otherwise, it is considered not to have coagulated and energy needs to be applied further.

[0031] Example 2 This embodiment describes in detail the system used to implement the method described in the first embodiment.

[0032] A tissue coagulation state assessment system, integrated inside a high-frequency electrosurgical unit, which is electrically connected to a bipolar high-frequency electrosurgical unit, includes the following modules: Signal acquisition module: used to acquire the voltage and current signals between the two electrodes of the electrosurgical head in real time; The impedance calculation module is used to receive voltage and current signals, calculate the organization's impedance data in real time, and store it as an impedance sequence of fixed length. The trend test module is used to perform Mann-Kendall trend tests on impedance sequences to obtain standardized statistics. The status judgment module is used to output the corresponding tissue closure status judgment result based on standardized statistics.

[0033] 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 determining the coagulation state of tissue using high-frequency electrosurgical units, characterized in that, Includes the following steps: S1: Initialize the operating parameters, which include the sampling frequency, sample size n, and significance level α; S2: According to the sampling frequency, the voltage and current signals between the two electrodes of the high-frequency electrosurgical unit are collected in real time to establish an equivalent circuit model of the tissue. The phase angle φ between the voltage and current signals is calculated, and the real part of the tissue impedance is calculated as the real-time impedance according to the formula R=(U / I)·cosφ, where U and I are the effective values ​​of the collected voltage and current signals, respectively. The real-time impedance is stored in the first-in-first-out data buffer in chronological order. The size of the data buffer is equal to the sample size n, forming an impedance sequence composed of the most recent n real-time impedances and updated in real time. S3: Perform the Mann-Kendall trend test on the impedance sequence to obtain the standardized statistic Z; S4: Calculate the critical value of the standard normal distribution at the significance level α. The standardized statistic Z is compared with the critical value. Comparison to determine the trend of tissue impedance changes: If the standardized statistic Z is greater than or equal to the critical value This indicates a significant upward trend in tissue impedance; if the standardized statistic Z is less than the critical value... If the negative of the standardized statistic Z is less than the critical value, it is considered that there is a significant downward trend; if the absolute value of the standardized statistic Z is less than the critical value... If so, it is determined that the current impedance has no significant trend; S5: Determine the tissue closure state based on the changing trend: When a significant upward trend is determined, the standardized statistic Z is compared with a preset threshold to further identify the intensity of the significant upward trend. If Z is greater than the preset threshold, the tissue is determined to be closed. When a significant downward trend, no significant trend, or a significant upward trend is determined but Z is not greater than the preset threshold, the tissue is determined not to be closed. Energy is then applied to the tissue, and steps S2 to S5 are returned until the tissue is determined to be closed.

2. The method as described in claim 1, characterized in that, In step S3, performing the Mann-Kendall trend test on the impedance sequence includes: calculating the sign statistic S and variance Var(S) of the impedance sequence, and calculating the standardized statistic Z based on the sign statistic S and variance Var(S), using the following formula: in, Let i and j be the impedance values ​​in the impedance sequence, and sign be the sign function. When, take 1, when When -1 is taken, The value is set to 0; n is the sample size; data with equal values ​​in the impedance sequence constitute the junction value, and m is the number of junction value groups. The number of data points in the p-th group is given. When the sample size n≥8, S approximately follows a normal distribution, and Z approximately follows a standard normal distribution.

3. A tissue coagulation state determination system, used to implement the tissue coagulation state determination method of claim 1, characterized in that, The system is integrated into the high-frequency electrosurgical unit and includes: The signal acquisition module is used to acquire the voltage and current signals between the two electrodes of the high-frequency electrosurgical unit in real time. The impedance calculation module is used to establish an equivalent circuit model of the tissue, calculate the phase angle φ between the voltage signal and the current signal, calculate the real part of the tissue impedance according to the formula R=(U / I)·cosφ as the real impedance, and store the real impedance in time order into a first-in-first-out data buffer of the same size as the sample size n, forming an impedance sequence composed of the most recent n real impedances. The trend test module is used to perform Mann-Kendall trend test on the impedance sequence to obtain the standardized statistic Z. The state determination module is used to calculate the critical value of the standard normal distribution at the significance level α. ,exist When it is determined that there is a significant upward trend, When it is determined that there is a significant downward trend, If no significant trend is found, Z is compared with a preset threshold when a significant upward trend is found to be found, and the strength of the significant upward trend is further identified. If Z is greater than the preset threshold, the result of the tissue coagulation is output; otherwise, the result of the tissue non-coagulation is output and energy continues to be applied.

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