Tissue coagulation state judgment method and system for high-frequency electrotome

Abstract

The invention 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; voltage and current between two electrodes of the high-frequency electrotome are collected in real time, real-time impedance of tissue between the two electrodes is calculated, and an impedance sequence in the latest period of time is formed; performing a Mangkendall trend test on the impedance sequence to obtain a standardized statistical magnitude; and judging the change trend of tissue impedance based on the standardized statistics, and determining the tissue coagulation state according to the change trend. According to the method disclosed by the invention, the Mangkendall trend test based on data statistics is adopted, so that the decreasing and increasing trends of tissue impedance and the significance degree of the trends can be effectively judged, and the accuracy and the reliability of judging the tissue coagulation state are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high-frequency electrotome, in particular to a tissue coagulation state judgment method and system for high-frequency electrotome. BACKGROUND

[0002] Bipolar high-frequency electrotome is a key instrument in minimally invasive surgery. Its working principle is to heat local tissue through high-frequency current between bipolar electrodes to achieve protein denaturation and blood vessel closure. In the process of bipolar high-frequency electrotome coagulating tissue, accurately judging the coagulation state of tissue is a key link to ensure the effect of surgery. At present, most systems rely on the intuitive observation of doctors or simple threshold method to judge, and the intuitive observation method relies on the experience of doctors to judge, and the impedance threshold method presets a fixed impedance value or impedance change rate as the coagulation standard. However, in the actual operation process, the impedance value of the tissue presents significant volatility, rather than an ideal smooth curve, and this fluctuation seriously affects the accuracy of the coagulation state judgment. SUMMARY

[0003] In view of the problems in the prior art, the present application provides a tissue coagulation state judgment method and system for high-frequency electrotome.

[0004] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows: A tissue coagulation state judgment method for high-frequency electrotome, comprising the following steps: S1: initializing running parameters; S2: real-time acquisition of voltage and current between two electrodes of the high-frequency electrotome, and calculation of real-time impedance of the tissue between the two electrodes to form an impedance sequence in the recent period of time; S3: Mann-Kendall trend test is performed on the impedance sequence to obtain a standardized statistic; S4: judging the change trend of the tissue impedance based on the standardized statistic, and determining the tissue coagulation state according to the change trend.

[0005] Preferably, the initialized running parameters include sampling frequency, sample size and significance level, and the values of the parameters can be adjusted according to different tissue types and actual requirements to lay a foundation for subsequent processing.

[0006] Preferably, in step S2, the calculation of 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 calculating the real-time impedance of the tissue between the two electrodes according to the formula . This step obtains the impedance value reflecting the real characteristics of the tissue by compensating the phase angle error.

[0007] Preferably, in step S2, the impedance sequence in the recent period of time is formed by storing real-time impedance data in a first-in-first-out data buffer in time sequence, the size of the data buffer is equal to the sample size, and the data in the impedance sequence is ensured to be impedance data in the recent period of time.

[0008] Preferably, in step S3, the Mann-Kendall trend test on the impedance sequence comprises: calculating a sign statistic S and a variance Var(S) of the impedance sequence, and calculating a standardized statistic Z based on the sign statistic S and the variance Var(S). This step is aimed at the characteristics of large fluctuation of tissue impedance data, and the Mann-Kendall trend test is used to enhance the robustness and accuracy of the method.

[0009] Preferably, in step S4, the determination of the change trend of the tissue impedance based on the standardized statistic comprises: calculating a critical value of a standard normal distribution under a given significance level comparing the absolute value of the standardized statistic Z with the critical value, if the standardized statistic Z is greater than the critical value , it is determined that there is a significant upward trend of the tissue impedance, if the standardized statistic Z is less than the opposite of the critical value , it is determined that there is a significant downward trend, and if the absolute value of the standardized statistic Z is less than the critical value , it is determined that there is no significant trend of the current impedance. This step reduces the misjudgment caused by random fluctuations through statistical significance test.

[0010] Preferably, the determination of the coagulation state of the tissue according to the change trend comprises: if there is a significant upward trend of the tissue impedance, comparing the standardized statistic Z with a preset threshold, if the standardized statistic Z is greater than the preset threshold, it is determined that the tissue has coagulated, otherwise it is determined that the tissue has not coagulated. This step further improves the accuracy of the determination of the coagulation state of the tissue by introducing a quantitative threshold to secondarily identify the intensity of the significant trend.

[0011] On the other hand, the present application proposes a tissue coagulation state determination system for implementing the above-mentioned tissue coagulation state determination method.

[0012] The present application introduces a Mann-Kendall trend test which is not required for data distribution and is not sensitive to abnormal values, realizes effective determination of the downward and upward trends of the tissue impedance, and can calculate the significance degree. Even if the collected impedance data does not meet the normal distribution assumption, the impedance has abnormal values and noise, the judgment result also has strong robustness and accuracy, so the present application realizes more accurate and reliable determination of the tissue coagulation. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 ​The temperature-impedance characteristic curve of the biological tissue in theory; Figure 2 The actual impedance change of the biological tissue when the biological tissue is subjected to energy output; Figure 3 The impedance model of the tissue between two electrodes of the high-frequency electrotome. DETAILED DESCRIPTION

[0014] To further illustrate the technical means and effects taken by the present application to achieve the predetermined purposes, the specific embodiments, structures, features and effects according to the present application are described in detail below in combination with the drawings and preferred embodiments.

[0015] Embodiment 1 The tissue has free ions (Na+, K+, Cl-, etc.), and the temperature rise promotes dissociation and ion migration, and the tissue impedance will decrease. This process is called the dissociation impedance reduction stage. When the temperature of the tissue continues to rise, the tissue temperature rise leads to evaporation of water in the tissue, and the activity space of the free ions decreases, and the ion migration rate decreases significantly. Although the ion concentration seems to increase due to the decrease in water, the tissue is close to a dehydrated state, and only a small amount of bound water remains, and the ions cannot freely migrate. At this time, the impedance of the tissue is rising, and this process is called the dry impedance increase stage. The theoretical impedance change trend of the tissue is as follows Figure 1 For the process of using a bipolar electrotome to coagulate tissue, the coagulation of the tissue is completed in the dry impedance increase stage. The coagulated tissue also has differences in type, thickness, main components, and the like. For different tissues, the degree of significant impedance increase trend at the completion of coagulation is also different.

[0016] In actual application, the impedance change trend of the tissue is as follows Figure 2 The host outputs energy to the tissue, and the temperature of the tissue gradually rises. In this process, the water activity is intense, and a steam pocket may be generated. Due to the existence of detection errors, there is a relatively large fluctuation in the change of the impedance of the tissue. In order to judge whether the tissue is coagulated based on the unstable impedance change of the tissue, the present application proposes a tissue coagulation state judgment method for a high-frequency electrotome. The present embodiment describes the specific implementation process of the method of the present application in detail, and specifically includes the following steps: Step one: initialize the running parameters.

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

[0018] When the operator starts the high-frequency electrotome and applies energy to the biological tissue, steps two to five are repeatedly executed. The signal acquisition module of the system starts to collect the voltage signal U and the current signal I output from the high-frequency generator to the tissue in real time at a preset sampling interval.

[0019] Step two: impedance data collection.

[0020] Collect the current I and voltage U between the two electrodes of the high-frequency electrotome at a preset sampling frequency.

[0021] To obtain accurate tissue impedance values, an electrical model of the tissue needs to be established. The impedance characteristics of the tissue, which contains free ions (Na⁺, K⁺, Cl⁻, etc.), can be represented by an equivalent circuit model composed of extracellular fluid resistance , intracellular fluid resistance , and cell membrane capacitance , as shown in Figure 3 . Therefore, the impedance Z of the tissue can be represented as: This model shows that the tissue impedance exhibits capacitive characteristics, rather than being purely resistive, resulting in a phase angle φ between the voltage and the current. To accurately reflect the real state changes of the tissue under the action of energy, phase compensation needs to be performed. Therefore, the phase angle φ between the voltage U and the current I also needs to be calculated, and the real-time impedance value R of the tissue at the current time is calculated by the following formula The calculated real-time impedance value R is stored in a first-in-first-out data buffer in chronological order. The size of the buffer is consistent with the preset sample size, thereby forming a real-time updated impedance sequence of length n .

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

[0023] The Mann-Kendall trend test is applied to the impedance sequence in the buffer. Specifically, the sign statistic S of the impedance sequence is calculated, and the calculation formula is where and are the i-th and j-th impedance values in the buffer, sign is the sign function, and if , then it is recorded as 1; if , 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 assumption of no trend is further calculated. Considering that the impedance sequence may have repeated values (ties), the variance needs to be corrected, and the calculation formula of the corrected variance is where n is the sample size, m is the number of groups of ties, is the number of p-th group of ties.

[0025] When all impedance data in the impedance sequence are not equal to each other, the sequence has no knot value, and the correction term At this time Simplify as: .

[0026] When there is a knot value, equal observations will cause a large , so that the actual fluctuation of S is smaller than that when there is no knot value. The role of the correction term is to subtract the amount of variation caused by the knot value from the original variance, ensuring The calculation is more accurate.

[0027] Further calculate the standardized statistic Z. When , S is approximately normally distributed, and Z is defined as: The standardized statistic Z is the result of the standardization of the symbol statistic S in the MK test. It converts the symbol statistic S into a value that follows a standard normal distribution, so that the trend can be quickly judged by the critical value of the normal distribution. The sign and size of the Z value directly reflect the direction and statistical significance of the trend.

[0028] Step four: trend judgment.

[0029] Calculate the critical value of the standard normal distribution under a given significance level α , and compare the absolute value of the Z value obtained in step three with the critical value , where the value of the significance level α is positive. If the absolute value of the standardized statistic Z is greater than or equal to the critical value , it is determined that there is a significant change trend in the impedance of the organization; specifically, if the standardized statistic Z is greater than the critical value , it is determined that there is a significant upward trend in the impedance of the organization, indicating that the organization has entered the dry and rising resistance stage; if the standardized statistic Z is less than the opposite of the critical value , it is determined that there is a significant downward trend, indicating that the organization is still in the dissociation and resistance reduction stage. If the absolute value of the standardized statistic Z is less than the critical value , it is determined that there is no significant trend in the current impedance, indicating that the organization is in the transition stage between the dry and rising resistance stage and the dissociation and resistance reduction stage.

[0030] If there is a significant upward trend in the tissue impedance, further determine whether the tissue is coagulated according to the size of the upward trend. Specifically, the size of the standardized statistic Z can be compared with a preset threshold value, and if the standardized statistic Z is greater than the preset threshold value, it is determined that the tissue has been coagulated, otherwise it is determined that the tissue has not been coagulated, and energy needs to be continued to be applied; or the impedance data can be fitted, the slope of the fitting curve at the current time point is calculated, and the slope is compared with a preset threshold value, and if the slope is greater than the preset threshold value, it is determined that the tissue has been coagulated, otherwise it is determined that the tissue has not been coagulated, and energy needs to be continued to be applied.

[0031] Embodiment 2 This embodiment describes in detail a system for implementing the method described in the first embodiment.

[0032] A tissue coagulation state judgment system integrated in a high-frequency electrotome host, the high-frequency electrotome host being electrically connected with a bipolar high-frequency electrotome, comprising the following modules: A signal acquisition module for acquiring voltage signals and current signals between two electrodes of the electrotome head in real time; An impedance calculation module for receiving the voltage and current signals, calculating tissue impedance data in real time and storing the impedance data as a fixed-length impedance sequence; A trend test module for performing a Mann-Kendall trend test on the impedance sequence to obtain a standardized statistic; A state judgment module for outputting a corresponding tissue coagulation state judgment result according to the standardized statistic.

[0033] The above is only a preferred embodiment of the present application, and does not limit the present application in any form. Although the present application has been disclosed as above with a preferred embodiment, it is not intended to limit the present application. Any person skilled in the art can make some changes or modifications to the above disclosed technical content to obtain equivalent embodiments with equivalent changes, without departing from the technical solution of the present application. Any modification, change, equivalent change and modification of the above embodiments, which does not depart from the technical solution of the present application, are still within the scope of the present application.

Claims

1. A tissue coagulation state determination method for a high-frequency electrotome, characterized by, The method comprises the following steps: S1: initializing running parameters; S2: collecting voltage and current between two electrodes of a high-frequency electrotome in real time, and calculating real-time impedance of tissue between the two electrodes to form an impedance sequence in a recent period of time; S3: performing Mann-Kendall trend test on the impedance sequence to obtain a standardized statistic; S4: judging a change trend of the tissue impedance based on the standardized statistic, and determining a coagulation state of the tissue according to the change trend.

2. The method of claim 1, wherein, The initialized running parameters include a sampling frequency, a sample size and a significance level.

3. The method of claim 2, wherein, In step S2, the calculating the real-time impedance of the tissue between the two electrodes comprises: calculating the phase angle φ between the voltage signal and the current signal, and according to the formula calculating the real-time impedance of the tissue between the two electrodes.

4. The method of claim 3, wherein, In step S2, the impedance sequence in the recent period of time is formed by storing real-time impedance data in a first-in-first-out data buffer in time sequence, and the size of the data buffer is equal to the size of the sample size.

5. The method of claim 2, wherein, In step S3, the Mann-Kendall trend test on the impedance sequence comprises: calculating a sign statistic S and a variance Var(S) of the impedance sequence, and calculating a standardized statistic Z based on the sign statistic S and the variance Var(S), and the calculation formula is: wherein, Zij is the i-th and j-th impedance value in the impedance sequence, and sign is a sign function, N is the sample size, and m is the number of groups of impedance values in the impedance sequence, Np is the number of impedance values in the p-th group.

6. The method of claim 2, wherein, In step S4, the judgment of the change trend of the tissue impedance based on the standardized statistic comprises: the critical value of the standard normal distribution at a given significance level the absolute value of the standardized statistic Z is compared to the critical value, and if the standardized statistic Z is greater than or equal to the critical value a significant upward trend in tissue impedance is determined; if the standardized statistic Z is less than the negative of the critical value a significant downward trend is determined; and if the absolute value of the standardized statistic Z is less than the critical value no significant trend in current impedance is determined.​ 7. The method of claim 6, wherein, In step S4, the determination of the coagulation state of the tissue according to the change trend comprises: if there is a significant upward trend in the tissue impedance, comparing the standardized statistic Z with a critical value, if the standardized statistic Z is greater than the critical value, determining that the tissue has been coagulated, otherwise determining that the tissue has not been coagulated.

8. A tissue coagulation state judging system for realizing the tissue coagulation state judging method according to claim 1, characterized by comprising: The method comprises: a signal collection module configured to collect voltage signals and current signals between two electrodes of a high-frequency electrotome in real time; an impedance calculation module configured to calculate real-time impedance values of tissue based on the voltage signals and the current signals and to obtain an impedance sequence; a trend test module configured to apply Mann-Kendall trend test on the impedance sequence to obtain a standardized statistic; a state judgment module configured to judge a change trend of the tissue impedance based on the standardized statistic, and to output a coagulation state judgment result of the tissue according to the change trend.

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