A central venous catheter tip intraoperative positioning system

Abstract

The application discloses a central venous catheter head end positioning system in operation, which comprises a double-channel electrocardio acquisition module, a signal preprocessing module, an electrocardio feature detection module, a parameter calculation module, a trend analysis and positioning judgment module, a prompt output module, a signal quality monitoring module and a storage module, the double-channel electrocardio acquisition module is used for synchronously acquiring a body surface electrocardio signal and a cavity electrocardio signal, the body surface electrocardio signal is acquired through a body surface electrode, and the cavity electrocardio signal is acquired through a catheter guide wire, a saline column in the catheter, a cavity electrode or a catheter communication conductive medium. The application belongs to the technical field of medical treatment, and particularly relates to a central venous catheter head end positioning system in operation, which effectively solves the problems of single positioning technology dimension, subjective misjudgment, weak anti-interference, no quantitative standard and incapability of accurately identifying a catheter overdeep state of the central venous catheter head end positioning system in operation on the market.

Description

Technical Field

[0001] This invention belongs to the field of medical technology, specifically referring to an intraoperative positioning system for the tip of a central venous catheter. Background Technology

[0002] Central venous catheters, including PICC, CVC, and port-a-catheter catheters, are widely used in various clinical scenarios such as cancer treatment, long-term parenteral nutrition, perioperative management, and critical care due to their core functions of long-acting infusion, nutritional support, hemodialysis, and intensive care support. The positioning accuracy of the catheter tip directly determines the safety and long-term patency of clinical use and is a core quality control indicator for central venous catheterization surgery.

[0003] Clinical practice has shown that abnormal catheter tip positioning can lead to a variety of serious complications: If the catheter is positioned too superficially, it can cause poor infusion flow, continuous irritation of the blood vessel wall, local thrombosis, and catheter displacement; if the catheter is positioned too deeply and invades the right atrium, it can induce arrhythmias, endocardial irritation, and in severe cases, lead to cardiac tamponade, heart damage, and other life-threatening risks. Therefore, real-time, precise, and objective intraoperative catheter tip positioning is crucial to ensuring the safety of central venous catheterization.

[0004] Intracardiac electrocardiographic localization is a non-invasive, real-time localization technology. Its core principle is to acquire intracardiac electrocardiographic signals through a catheter guidewire, saline column, or intracardiac electrode, and determine the position of the catheter tip based on changes in P-wave amplitude during catheter advancement. Current technology generally suggests that as the catheter tip approaches the superior vena cava-right atrium junction, the positive amplitude of the intracardiac P-wave gradually increases; after the catheter enters the right atrium, the P-wave exhibits biphasic or negative characteristics.

[0005] Existing intracavitary electrocardiographic localization systems and methods have many core technical defects:

[0006] 1. The positioning dimension is singular, relying solely on the positive amplitude change of the P wave to make a judgment, which cannot effectively identify the excessive depth of the catheter after it has entered the right atrium, making it difficult to avoid the risk of invasive cardiac damage;

[0007] 2. Poor judgment tolerance: When the catheter approaches the target positioning area, the positive amplitude of the P wave is prone to plateau. When the catheter is slightly displaced, the amplitude does not change significantly. It relies entirely on the operator's subjective visual judgment, resulting in strong subjectivity and high error rate.

[0008] 3. Low utilization rate of waveform information: The negative P wave and biphasic P wave characteristics generated when the catheter is too deep are not quantitatively analyzed, resulting in the loss of core positioning basis;

[0009] 4. Lack of individualized adaptation: There are significant individual differences in the baseline P wave amplitude on the body surface of different patients. Current technology uses absolute amplitude determination criteria, which has poor adaptability and high misjudgment rate.

[0010] 5. Weak anti-interference ability: factors such as abnormal guidewire contact during the operation, unstable conductivity of the saline column, micro-movement of the patient's limbs, electromyographic interference, and power frequency interference can easily cause short-term fluctuations in the P wave amplitude, leading to momentary misjudgment.

[0011] 6. There are no standardized quantitative indicators. The entire process relies on manual observation of waveform changes. There are no objective positioning parameters that can be calculated, repeated, and traced, making it impossible to achieve automated and standardized positioning judgment. Summary of the Invention

[0012] In response to the above situation and to overcome the shortcomings of the existing technology, this invention proposes a central venous catheter tip intraoperative positioning system, which effectively solves the problems of single positioning dimension, subjective misjudgment, weak anti-interference, lack of quantitative standards, and inability to accurately identify the state of the catheter being too deep in the current market.

[0013] The technical solution adopted in this invention is as follows: This invention proposes a central venous catheter tip intraoperative positioning system, comprising a dual-channel ECG acquisition module, a signal preprocessing module, an ECG feature detection module, a parameter calculation module, a trend analysis and positioning judgment module, a prompt output module, a signal quality monitoring module, and a storage module. The dual-channel ECG acquisition module is used to simultaneously acquire surface ECG signals and intracavitary ECG signals. Surface ECG signals are acquired through surface electrodes, while intracavitary ECG signals are acquired through catheter guidewires, intracavitary saline columns, intracavitary electrodes, or a conductive medium connected to the catheter. The dual-channel ECG acquisition module uses a fixed sampling rate of 500Hz and is equipped with an ADS1292R ECG acquisition chip to achieve synchronous, high-precision acquisition of dual-channel signals and convert the raw ADC data into microvolt units for output. The signal preprocessing module interfaces with the dual-channel ECG acquisition module and is used to perform baseline drift suppression and 50Hz power frequency notch filtering on the surface ECG signals and intracavitary ECG signals. For R-peak detection, a 5Hz-25Hz bandpass filter is used, and for P-wave feature analysis, a 0.5Hz-40Hz bandpass filter is used. The system filters out intraoperative electromyography, motion, and power frequency noise interference. The ECG feature detection module is connected to the signal preprocessing module to perform QRS wave R-peak detection, P-wave feature window construction, and P-wave peak extraction. The ECG feature detection module uses a modified Pan-Tompkins algorithm to accurately locate the R-peak and constructs a dedicated P-wave search window using the R-peak as a time anchor point. The default window range is 60ms-250ms before the R-peak, with 90ms-220ms before the R-peak being the priority detection area. If no effective P-wave feature is found in the priority detection area, the window automatically expands to the complete range. The window is set as follows: 0ms-60ms before the R peak is a QRS protection zone, which does not participate in P wave determination; based on the corrected baseline, the surface P wave positive peak value Ps+, the intracavitary P wave positive peak value Pi+, and the intracavitary P wave negative peak value Pi− are extracted, where Pi− is the absolute value of the maximum negative peak value of the intracavitary P wave; the parameter calculation module is connected to the ECG feature detection module and is used to calculate standardized quantitative positioning parameters based on the extracted P wave feature parameters, specifically including the positive enhancement coefficient Kpos, the negative enhancement coefficient Kneg, the comprehensive positioning index F, and the biphasic wave proportion Rneg;

[0014] Wherein, the positive enhancement coefficient is: Kpos = Pi+ / Ps+;

[0015] Negative enhancement coefficient: Kneg = Pi− / Ps+;

[0016] Comprehensive positioning index: F = (Kpos−β×Kneg) / (Kpos + β×Kneg +ε);

[0017] Biphasic ratio: Rneg = Kneg / (Kpos +ε);

[0018] In the formula, β is the negative wave weighting coefficient, with a value of 0.8-2.0, preferably 1.2; ε is the numerical stability term, with a value of 0.01-0.20, preferably 0.05, used to avoid the denominator being zero and improve parameter stability; the parameter calculation module has a built-in multi-beat smoothing filter unit, which performs median filtering on the characteristic parameters and calculated parameters of 5-8 consecutive effective heartbeats to eliminate parameter anomalies caused by instantaneous signal fluctuations; the trend analysis and positioning judgment module is connected to the parameter calculation module, and is used to analyze the dynamic change trend of the smoothed comprehensive positioning index F, the biphasic wave ratio Rneg threshold, and the anti-shake priority machine. The system controls and determines the real-time status of the catheter tip. The prompt output module outputs four types of visual and voice prompts based on the positioning judgment result: forward, in place, retreat, and no judgment. The signal quality monitoring module monitors the status of dual-channel ECG signals in real time, identifies abnormal conditions such as lead dropout, signal saturation, baseline abnormality, Ps+ below the effective threshold of 20μV, unstable R peak detection, atrial fibrillation, and unrecognizable P waves, and triggers a signal abnormality locking mechanism. The storage module stores the original ECG signal, filtered signal, feature parameters, calculation parameters, positioning judgment result, and operation log in real time, enabling data traceability.

[0019] Furthermore, the specific judgment logic of the trend analysis and positioning judgment module is as follows:

[0020] 1. Advancing status: The F parameter continues to rise and Rneg < 0.2, indicating that the catheter tip is approaching the vena cava-right atrium junction, triggering the advancing indication condition;

[0021] 2. Position Status: When the F parameter reaches its peak or enters a stable plateau period, and Rneg < 0.2, it is determined that the catheter tip is in the optimal target positioning area, triggering the positioning prompt condition;

[0022] 3. Too Deep Retraction Status: The Rneg parameter continues to rise while the F parameter decreases synchronously, indicating that the catheter tip has invaded the right atrium and is too deep; when Rneg ≥ 0.3, the priority of the withdrawal prompt is increased to strengthen the risk warning.

[0023] 4. Abnormal temporary judgment state: When the signal quality does not meet the valid judgment conditions, the output result is locked and the conduit position is not judged.

[0024] Furthermore, the trend analysis and positioning judgment module has a built-in slope trend judgment mechanism. It selects five consecutive smoothed F parameters and calculates the slope of change through a linear regression algorithm. An F increase slope threshold ≥ +0.02 / beat is judged as a continuous increase, an F decrease slope threshold ≤ -0.02 / beat is judged as a continuous decrease, and an absolute slope value < ±0.02 / beat and an F value close to the historical peak is judged as a stable platform state. The F parameter fluctuation tolerance is set to 0.05 to avoid misjudgment due to small numerical fluctuations.

[0025] Furthermore, the trend analysis and positioning judgment module has a built-in anti-jitter continuous confirmation mechanism and multi-level priority rules: if the forward condition is met for 3 consecutive effective smoothing cycles, a forward prompt is output; if the arrival condition is met for 3 consecutive effective smoothing cycles, an arrival prompt is output; if the retreat condition is met for 2 consecutive effective smoothing cycles, a retreat prompt is output. The output priority from high to low is as follows: signal abnormality is not judged, retreat prompt, arrival prompt, forward prompt, to prevent erroneous output when multiple conditions are superimposed.

[0026] Furthermore, the effective signal judgment criteria of the signal quality monitoring module are: the positive peak value of the P wave on the body surface Ps+ ≥ 20μV, no lead loss, no signal saturation, continuous and stable R peak detection, and P wave window noise below a preset threshold; if any condition is not met, the signal is determined to be invalid and the positioning output is locked.

[0027] The beneficial effects of this invention using the above structure are as follows: The central venous catheter tip intraoperative positioning system proposed in this solution: 1. Utilizes the positive enhancement characteristics and negative, biphasic distortion characteristics of the intravascular P wave to construct a dual-parameter judgment system, which can accurately distinguish three core states: catheter approaching the target area, precise positioning, and right atrial depth. This completely solves the technical defect of traditional single positive amplitude judgment, which cannot identify catheter depth, thus avoiding the risk of cardiac injury. The dual-dimensional quantitative judgment provides higher positioning accuracy. 2. Using the patient's own surface P wave peak value as a normalized reference benchmark eliminates the influence of individual differences in the baseline ECG parameters of different patients. Compared with the traditional absolute amplitude judgment standard, it significantly reduces the misjudgment rate due to individual differences, making it suitable for clinical patients of all ages and physical conditions, with stronger adaptability. 3. It pioneers a comprehensive positioning index and a biphasic wave ratio quantitative index. The system transforms waveform characteristics into calculable, quantifiable, and traceable numerical parameters, completely eliminating the drawbacks of traditional subjective judgment by the naked eye. It solves the problem of ambiguity in judging the plateau phase of P wave amplitude, standardizes and repeats the positioning results, and constructs a comprehensive quantitative model for more objective judgment. Fourth, it integrates multiple filtering and noise reduction, multi-beat median smoothing, slope trend determination, and anti-shake continuous confirmation mechanisms, which can effectively suppress signal fluctuations caused by intraoperative motion artifacts, electromyographic interference, power frequency interference, and unstable conductive media. It is suitable for complex intraoperative clinical environments, and its multi-level anti-interference design ensures higher stability. Fifth, the system can automatically output four types of precise prompts in real time: forward, in place, retreat, and signal abnormality. No professional interpretation of ECG waveforms is required from the operator, lowering the operational threshold, reducing human error, and significantly improving the efficiency of catheter placement surgery. Automated intelligent prompts make operation more convenient. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the overall process structure of an intraoperative positioning system for the tip of a central venous catheter proposed in this invention.

[0029] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof. Detailed Implementation

[0030] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0031] Example 1: Basic Central Venous Catheter Tip Intraoperative Positioning System

[0032] like Figure 1 As shown, the present invention proposes an intraoperative positioning system for the tip of a central venous catheter, comprising a dual-channel electrocardiogram (ECG) acquisition module, a signal preprocessing module, an ECG feature detection module, a parameter calculation module, a trend analysis and positioning judgment module, a prompt output module, a signal quality monitoring module, and a storage module.

[0033] The system workflow is as follows:

[0034] S1. Synchronous signal acquisition: The electrocardiogram (ECG) signal on the body surface is acquired through surface electrodes, and the ECG signal in the heart cavity is acquired through the guidewire of the central venous catheter. The raw ECG data is acquired simultaneously through dual channels and converted into microvolts.

[0035] S2. Signal preprocessing: Baseline drift suppression and 50Hz power frequency notch filtering are performed on the dual-channel signals respectively; the R-peak detection channel uses 5Hz-25Hz bandpass filtering and the P-wave analysis channel uses 0.5Hz-40Hz bandpass filtering to filter out intraoperative clutter interference.

[0036] S3. R-peak detection and window construction: The modified Pan-Tompkins algorithm is used to accurately locate the R-peak of the QRS wave on the body surface of the electrocardiogram; the P-wave detection window is constructed, with the priority detection area being 90ms-220ms before the R-peak, which is extended to 60ms-250ms when there is no effective signal, and the 0ms-60ms before the R-peak is locked as the QRS protection zone.

[0037] S4. Feature parameter extraction: Baseline correction is performed on the window signal, and the positive peak value of the surface P wave Ps+, the positive peak value of the cavity P wave Pi+, and the absolute value of the negative peak value of the cavity P wave Pi− are extracted.

[0038] S5. Core Parameter Calculation: Substituting the fixed optimal parameters β=1.2 and ε=0.05, calculate Kpos, Kneg, comprehensive positioning index F, and biphasic wave ratio Rneg. The calculation formulas are as follows:

[0039] Kpos = Pi+ / Ps+;

[0040] Kneg = Pi− / Ps+;

[0041] F = (Kpos − 1.2×Kneg) / (Kpos + 1.2×Kneg + 0.05);

[0042] Rneg = Kneg / (Kpos + 0.05).

[0043] S6. Parameter smoothing and noise reduction: Select the parameters of the 8 most recent valid heartbeats and use median filtering to eliminate instantaneous signal fluctuations.

[0044] S7. Positioning Judgment and Prompt Output: Determine the catheter status based on preset thresholds: Rneg first threshold 0.2, second threshold 0.3; if F continues to rise and Rneg < 0.2, output forward prompt; if F reaches its peak plateau and Rneg < 0.2, output position prompt; if Rneg rises and F falls, output retreat prompt; if the signal is abnormal, output no judgment prompt.

[0045] Example 2: High-precision positioning system with slope trend determination

[0046] like Figure 1 As shown, this embodiment, based on Embodiment 1, adds an F-parameter slope trend determination mechanism to improve dynamic positioning accuracy. It is suitable for intraoperative positioning in complex clinical scenarios such as critically ill patients and patients with arrhythmias. Five consecutive smoothed F-parameters (F1-F5) are selected, and the slope of parameter changes is calculated using a linear regression algorithm. Determination thresholds are set: an F-parameter increase slope ≥ +0.02 / beat indicates continuous approach to the target area; a F-parameter decrease slope ≤ -0.02 / beat indicates catheter retraction due to excessive depth; and an absolute slope value < ±0.02 / beat with the difference between the current F-value and the historical peak value ≤ 0.05 indicates a stable positioning state. By quantifying the trend through dynamic slope, the lag of single-parameter threshold determination is avoided, improving the real-time performance and accuracy of positioning.

[0047] Example 3: Stable Output Positioning System with Anti-jitter Priority

[0048] like Figure 1As shown, this embodiment, based on embodiments 1 and 2, adds a continuous confirmation mechanism to prevent jitter and a multi-level output priority to solve the problem of frequent prompt changes caused by small signal fluctuations during surgery, adapting to scenarios involving patient micro-movement and respiratory interference during surgery. The system sets a continuous confirmation cycle: the forward condition must be met for 3 consecutive smooth cycles, the arrival condition must be met for 3 consecutive smooth cycles, and the retreat condition must be met for 2 consecutive smooth cycles before the corresponding prompt can be output. At the same time, the output priority is set as follows: signal abnormality is not judged > retreat prompt > arrival prompt > forward prompt. When multiple conditions are superimposed, the higher priority prompt is output first, especially strengthening the risk warning of catheter being too deep, eliminating false prompts and prompt changes, and improving the clinical stability of the system.

[0049] Example 4: High-precision signal quality control and positioning system

[0050] like Figure 1 As shown, this embodiment integrates a multi-dimensional signal quality monitoring mechanism to accurately filter invalid signals and further reduce the false judgment rate. The system monitors lead status, signal saturation status, baseline drift, power frequency interference intensity, R peak stability, and P wave identifiability in real time. A minimum effective threshold of 20μV for Ps+ is set. When the baseline P wave amplitude is too low, P wave window noise exceeds the standard, R peak fluctuations are abnormal, or atrial fibrillation is suspected, the system directly locks the positioning output, pauses position judgment, and indicates signal abnormality, avoiding erroneous judgments based on invalid signals. This approach is suitable for special patient groups with arrhythmias and poor signal quality.

[0051] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0052] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

[0053] The present invention and its embodiments have been described above. This description is not restrictive, and the accompanying drawings are only one embodiment of the present invention; the actual structure is not limited thereto. In conclusion, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the spirit of the invention, such designs should fall within the protection scope of the present invention.

Claims

1. A central venous catheter tip intraoperative positioning system, characterized in that: The system comprises a dual-channel ECG acquisition module, a signal preprocessing module, an ECG feature detection module, a parameter calculation module, a trend analysis and localization judgment module, a prompt output module, a signal quality monitoring module, and a storage module. The dual-channel ECG acquisition module is used to simultaneously acquire surface ECG signals and intracavitary ECG signals. Surface ECG signals are acquired through surface electrodes, while intracavitary ECG signals are acquired through catheter guidewires, intracatheter saline columns, intracavitary electrodes, or a conductive medium connected to the catheter. The dual-channel ECG acquisition module uses a fixed sampling rate of 500Hz and is equipped with an ADS1292R ECG acquisition chip to achieve synchronous, high-precision acquisition of dual-channel signals and convert the raw ADC data into microvolt units for output. The signal preprocessing module interfaces with the dual-channel ECG acquisition module to perform baseline drift suppression and 50Hz power frequency notch filtering on surface ECG and intracavitary ECG signals. For R-peak detection, a 5Hz-25Hz bandpass filter is used; for P-wave feature analysis, a 0.5Hz-40Hz bandpass filter is used to filter out intraoperative electromyography, motion, and power frequency noise interference. The ECG feature detection module is connected to the signal preprocessing module to perform QRS wave R-peak detection, P-wave feature window construction, and P-wave peak extraction. The ECG feature detection module uses a modified Pan-Tompkins algorithm to accurately locate the R-peak, constructing a dedicated P-wave search window with the R-peak as the time anchor point. The default window range is 60ms-250ms before the R-peak, with 90ms-220ms before the R-peak designated as the priority detection zone. If no valid P-wave feature is found in the priority detection zone, the window automatically expands to the full window. The window is set to 0ms before the R-peak. The s-60ms range is a QRS protection zone and is not involved in P wave determination. Based on the corrected baseline, the surface P wave positive peak value Ps+, the intracavitary P wave positive peak value Pi+, and the intracavitary P wave negative peak value Pi− are extracted, where Pi− is the absolute value of the maximum negative peak value of the intracavitary P wave. The parameter calculation module is connected to the ECG feature detection module and is used to calculate standardized quantitative positioning parameters based on the extracted P wave feature parameters, specifically including the positive enhancement coefficient Kpos, the negative enhancement coefficient Kneg, the comprehensive positioning index F, and the biphasic wave proportion Rneg. Wherein, the positive enhancement coefficient is: Kpos = Pi+ / Ps+; Negative enhancement coefficient: Kneg = Pi− / Ps+; Comprehensive positioning index: F = (Kpos−β×Kneg) / (Kpos + β×Kneg +ε); Biphasic ratio: Rneg = Kneg / (Kpos +ε); In the formula, β is the negative wave weighting coefficient, with a value of 0.8-2.0, preferably 1.2; ε is the numerical stability term, with a value of 0.01-0.20, preferably 0.05, used to avoid the denominator being zero and improve parameter stability; the parameter calculation module has a built-in multi-beat smoothing filter unit, which performs median filtering on the characteristic parameters and calculated parameters of 5-8 consecutive effective heartbeats to eliminate parameter anomalies caused by instantaneous signal fluctuations; the trend analysis and positioning judgment module is connected to the parameter calculation module, and is used to analyze the dynamic change trend of the smoothed comprehensive positioning index F, the biphasic wave ratio Rneg threshold, and the anti-shake priority machine. The system controls and determines the real-time status of the catheter tip. The prompt output module outputs four types of visual and voice prompts based on the positioning judgment result: forward, in place, retreat, and no judgment. The signal quality monitoring module monitors the status of dual-channel ECG signals in real time, identifies abnormal conditions such as lead dropout, signal saturation, baseline abnormality, Ps+ below the effective threshold of 20μV, unstable R peak detection, atrial fibrillation, and unrecognizable P waves, and triggers a signal abnormality locking mechanism. The storage module stores the original ECG signal, filtered signal, feature parameters, calculation parameters, positioning judgment result, and operation log in real time, enabling data traceability.

2. The intraoperative positioning system for the tip of a central venous catheter according to claim 1, characterized in that: The specific judgment logic of the trend analysis and positioning judgment module is as follows:

1. Advancing status: The F parameter continues to rise and Rneg < 0.2, indicating that the catheter tip is approaching the vena cava-right atrium junction, triggering the advancing indication condition; 2. Position Status: When the F parameter reaches its peak or enters a stable plateau period, and Rneg < 0.2, it is determined that the catheter tip is in the optimal target positioning area, triggering the positioning prompt condition; 3. Too Deep Retraction Status: The Rneg parameter continues to rise while the F parameter decreases synchronously, indicating that the catheter tip has invaded the right atrium and is too deep; when Rneg ≥ 0.3, the priority of the withdrawal prompt is increased to strengthen the risk warning.

4. Abnormal temporary judgment state: When the signal quality does not meet the valid judgment conditions, the output result is locked and the conduit position is not judged.

3. The intraoperative positioning system for the tip of a central venous catheter according to claim 2, characterized in that: The trend analysis and positioning judgment module has a built-in slope trend judgment mechanism. It selects five consecutive smoothed F parameters and calculates the slope of change through a linear regression algorithm. An F increase slope threshold ≥ +0.02 / beat is judged as a continuous increase, an F decrease slope threshold ≤ -0.02 / beat is judged as a continuous decrease, and an absolute slope value < ±0.02 / beat and an F value close to the historical peak is judged as a stable platform state. The F parameter fluctuation tolerance is set to 0.05 to avoid misjudgment due to small numerical fluctuations.

4. The intraoperative positioning system for the tip of a central venous catheter according to claim 3, characterized in that: The trend analysis and positioning judgment module has a built-in anti-shake continuous confirmation mechanism and multi-level priority rules: if the forward condition is met for 3 consecutive effective smoothing cycles, a forward prompt is output; if the arrival condition is met for 3 consecutive effective smoothing cycles, an arrival prompt is output; if the retreat condition is met for 2 consecutive effective smoothing cycles, a retreat prompt is output. The output priority is from high to low as follows: signal abnormality is not judged, retreat prompt, position prompt, and forward prompt, to prevent erroneous output when multiple conditions are superimposed.

5. The intraoperative positioning system for the tip of a central venous catheter according to claim 4, characterized in that: The effective signal judgment criteria of the signal quality monitoring module are: positive peak value of P wave on the body surface Ps+≥20μV, no lead loss, no signal saturation, continuous and stable R peak detection, and P wave window noise below the preset threshold; if any condition is not met, the signal is judged to be invalid and the positioning output is locked.

Images