Online calibration method and online calibration device for extracorporeal membrane oxygenation system

Abstract

The invention relates to an online calibration method for an extracorporeal membrane oxygenation system. A time difference method flow sensor and a Hall sensor collect data, and a host calculates blood pump flow, blood pump rotating speed data and relative indicating value errors and judges whether the data are out of tolerance or not. The on-line calibration device realizes real-time data acquisition and calibration at the stage of treating a patient with the blood pump flow and the blood pump rotating speed, and comprises an on-line calibration device host, a time difference method flow sensor, a Hall sensor and a data line. The Hall sensor is connected with the online calibration device host, one end of the time difference method flow sensor is connected with the online calibration device host, the other end of the time difference method flow sensor is connected with an extracorporeal circulation perfusion pipeline of the extracorporeal membrane oxygenation system, and one end of a pump head of a blood pump of the extracorporeal membrane oxygenation system is connected with a patient through the extracorporeal circulation perfusion pipeline. And the other end is connected with a patient through an extracorporeal circulation drainage pipeline. The accuracy of measured data is improved, and the problem that a conventional optical non-contact rotating speed measuring method cannot be suitable for online calibration of the rotating speed of the blood pump of the in-vitro membrane lung oxygenation system is solved.

Description

Technical Field

[0001] The present invention relates to an online calibration method in the field of medical testing instruments, and in particular to an online calibration method and an online calibration device for an extracorporeal membrane oxygenation system. Background Art

[0002] Extracorporeal membrane oxygenation (ECMO) systems are considered an effective life-saving treatment for circulatory failure and are widely used to support patients with various types of severe respiratory and circulatory failure. With the widespread clinical application of ECMO systems, the accuracy of key parameters during the intraoperative treatment phase—blood pump flow and speed—must not be overlooked. Blood pump flow is an important indicator for clinically evaluating a patient's oxygen metabolism, monitoring their condition, and determining the timing of ventilator removal. Blood pump speed is a key parameter to monitor and adjust during clinical treatment, and its accuracy is crucial for maintaining stable vital signs and reducing complications such as hemolysis and coagulation. Compared to traditional extracorporeal circulation, ECMO systems are complex, require high technical requirements, require longer patient stays on the machine, and have a higher complication rate and clinical risk. According to international authoritative assessments, ECMO systems are among the most clinically risky large medical devices in use in hospitals. Therefore, the accuracy of these key parameters—blood pump flow and speed—during ECMO treatment directly impacts the health and safety of patients. Regular measurement calibration is an important part of preventive maintenance in clinical quality control and is also the fundamental means to ensure the accuracy of measurement values ​​of related medical equipment.

[0003] Because extracorporeal membrane oxygenation (ECMO) systems are typically operated for extended periods of time, typically for weeks, the accuracy of the blood pump flow and speed during treatment is crucial to the health and safety of patients. To effectively mitigate the clinical risks associated with ECMO treatment, both blood pump flow and speed require online calibration.

[0004] Extracorporeal membrane oxygenation (ECMO) systems are critical equipment for the clinical treatment and emergency rescue of patients with severe respiratory / circulatory failure. Currently, clinical quality control of ECMO systems in use in medical institutions is limited to manufacturers performing equipment maintenance when the systems are not connected to patients and are not undergoing online treatment. Key parameters such as blood pump flow and speed are not effectively calibrated and traced, and the accuracy of these parameters cannot be guaranteed, posing a significant medical risk. Furthermore, when calibrating an ECMO system while it is in use, the device's circulation circuit is filled with the patient's blood. To ensure patient safety, non-invasive or contactless calibration methods should be used when calibrating the blood pump flow and speed, without contacting the patient's blood.

[0005] Currently, there are the following technical problems in the online calibration of key parameters of extracorporeal membrane oxygenation systems:

[0006] 1. For the online calibration of blood pump flow, it is necessary to develop a dedicated flow data processing algorithm based on the existing time-difference flow algorithm, and improve the existing algorithm according to the pipeline structure of the extracorporeal membrane oxygenation system, the flow characteristics of the measurement medium (blood viscosity, sound velocity), and the flow field characteristics of different flow segments under common clinical treatment modes such as VV-ECMO and VA-ECMO.

[0007] 2. For online calibration of blood pump speed, Figure 1A 、 Figure 1B As shown in the figure, for the blood pump speed, when treating patients, the blood pump head is filled with patient blood and the rotating body in the pump head is invisible. Therefore, it is necessary to solve the problem that conventional optical non-contact speed measurement methods such as stroboscopic method and laser marking method cannot be used to measure the blood pump speed.

[0008] In view of the above-mentioned defects in the existing technology, the inventor has continuously researched and designed, and after repeated trial production and improvement, finally created the present invention which is of real practical value. Summary of the Invention

[0009] The purpose of the present invention is to overcome the shortcomings of existing technologies and provide a novel structure of an online calibration method and online calibration device for an extracorporeal membrane oxygenation system. The technical problem to be solved is to enable an online calibration device to accurately collect the blood pump flow rate and blood pump speed of the extracorporeal membrane oxygenation system, thereby realizing real-time online calibration of the blood pump flow rate and blood pump speed during clinical treatment of patients, thereby being more suitable for practical use.

[0010] Another object of the present invention is to overcome the defects of the existing technology and provide a new online calibration method and online calibration device for an extracorporeal membrane oxygenation system. The technical problems to be solved are: first, using a flow sensor based on the time difference method in combination with a developed algorithm to solve the problem of calibrating blood pump flow data in different flow segments of typical clinical treatment modes VV-ECMO and VA-ECMO; second, using an algorithm developed based on a Hall sensor to set different voltage thresholds and detect the rotation of the magnetic poles on the rotating body in the blood pump head to generate a Hall voltage pulse signal, thereby realizing online calibration of the blood pump speed of the extracorporeal membrane oxygenation system during the patient treatment stage. This effectively solves the problem that the rotating body in the blood pump head is invisible when the blood pump head is filled with patient blood during online calibration, and conventional optical non-contact speed measurement methods such as the stroboscopic method and laser marking method are not applicable to the online calibration of the blood pump speed of the extracorporeal membrane oxygenation system. The method improves the accuracy of the calibration data and adapts to various clinical usage scenarios, making it more suitable for practical use.

[0011] Currently, there is no calibration device available for online calibration of extracorporeal membrane oxygenation (ECMO) systems, leaving routine calibration and clinical quality control of blood pump flow and speed largely unproven. To address this issue, the present invention aims to perform online calibration and measurement of blood pump flow and speed during the in-use phase of ECMO treatment for patients under commonly used clinical treatment modes, such as venovenous ECMO and vavoxelaneous ECMO. This provides equipment and technical capabilities for addressing in-use calibration and clinical quality control issues for ECMO systems, effectively ensuring the quality of clinical use of ECMO systems.

[0012] The purpose of the present invention and the technical problem solved are achieved by adopting the following technical solutions. According to the present invention, a calibration method of an online calibration device for an extracorporeal membrane oxygenation system mainly comprises the following steps:

[0013] Step 1: Connect the online calibration device to the extracorporeal membrane oxygenation system circuit to be calibrated

[0014] Before online calibration of the extracorporeal membrane oxygenation system, install the transit time flow sensor of the online calibration device on the extracorporeal circulation perfusion pipeline of the extracorporeal membrane oxygenation system to be calibrated through the pipeline slot. To ensure stable liquid flow in the pipeline, the pipeline where the transit time flow sensor is installed should be straight without any height difference, and at least 10 cm of straight pipe section should be reserved before and after the transit time flow sensor installation location.

[0015] Fix the Hall sensor of the online calibration device on the measuring bracket. Adjust the bracket so that the measuring surface of the Hall sensor touches the upper surface of the blood pump head of the extracorporeal membrane oxygenation system, and ensure that the axis of the Hall sensor is perpendicular to the rotation plane of the rotating body in the blood pump head.

[0016] Step 2: Start the blood pump flow calibration function and collect data through the time difference flow sensor

[0017] The calibrator starts the blood pump flow calibration program by clicking on the touch screen of the online calibration device host. The online calibration device host transmits the blood pump flow calibration start instruction to the time difference flow sensor through the first data line interface of the data line. After the time difference flow sensor receives the instruction, the first ultrasonic transmitting and receiving unit transmits an ultrasonic signal to the second ultrasonic transmitting and receiving unit and starts timing. The ultrasonic signal is transmitted through the patient's blood flowing in the extracorporeal circulation perfusion tube and is received by the second ultrasonic transmitting and receiving unit. After the second ultrasonic transmitting and receiving unit receives the ultrasonic signal, the timing is stopped to obtain the ultrasonic signal downstream propagation time. After that, the second ultrasonic transmitting and receiving unit transmits an ultrasonic signal to the first ultrasonic transmitting and receiving unit and starts timing. The ultrasonic signal is transmitted through the patient's blood flowing in the extracorporeal circulation perfusion tube and is received by the first ultrasonic transmitting and receiving unit. After the first ultrasonic transmitting and receiving unit receives the ultrasonic signal, the timing is stopped to obtain the reverse flow propagation time of the ultrasonic signal. When designing the blood pump flow data acquisition program, the ultrasonic signal is transmitted and received multiple times to extend the ultrasonic sound path, thereby reducing the time difference measurement error, thereby improving the measurement accuracy of the blood pump flow at a small flow point of the present invention. Specifically, different repeated acquisition times are set according to the measured blood pump flow range. The corresponding relationship between the repeated acquisition times and the blood pump flow is shown in Table 1. The time difference flow sensor records N times of ultrasonic signal downstream propagation time and N times of ultrasonic signal reverse flow propagation time measurement data respectively;

[0018] Table 1 Correspondence between the number of repeated acquisitions and the blood pump flow range in data processing

[0019]

[0020] At the same time, the temperature measuring element in the transit time flow sensor measures the blood temperature data in the extracorporeal circulation perfusion circuit of the calibrated extracorporeal membrane oxygenation system;

[0021] The time difference flow sensor transmits the collected N ultrasonic signal downstream propagation time, N ultrasonic signal upstream propagation time measurement data and blood temperature data to the online calibration device host through the first data line interface and the data line;

[0022] Step 3: The online calibration device host calculates the blood pump flow data based on the internal algorithm

[0023] The time difference flow sensor measures the difference in propagation time between the ultrasonic signal in the downstream and upstream directions. The relationship between the measured difference in propagation time between the ultrasonic signal in the downstream and upstream directions and the flow velocity of the fluid to be measured is used to calculate the flow velocity of the measuring medium in the pipeline, and then the measuring medium flow is calculated in combination with the cross-sectional area of ​​the pipeline. When the blood pump flow is actually calibrated, the main unit of the online calibration device calculates the blood pump flow data of the calibrated extracorporeal membrane oxygenation system through the internal algorithm formula (1-1) and formula (1-2);

[0024] The uncorrected blood pump flow is calculated using formula (1-1):

[0025]

[0026] Where: Q is the uncorrected blood pump flow rate calculated by the main unit of the online calibration device; c is the sound velocity of the ultrasonic signal in human blood; d is the inner diameter of the extracorporeal perfusion pipe of the extracorporeal membrane oxygenation system; T2 is the Nth reverse flow propagation time of the ultrasonic signal; T1 is the Nth downstream propagation time of the ultrasonic signal; N is the number of repeated transmissions and receptions of the ultrasonic signal, which can be obtained by looking up Table 1; α is the angle between the line connecting the first ultrasonic transmitting and receiving unit and the second ultrasonic transmitting and receiving unit in the sensor and the geometric centerline of the pipe;

[0027] The blood temperature is collected by the temperature measuring element in the time difference flow sensor, and the sound velocity of the ultrasonic signal in the human blood in the algorithm formula (1-1) is corrected for temperature. After adding the flow velocity correction coefficient in the formula (1-1) according to the blood flow state, the blood pump flow rate after the above algorithm correction can be calculated by (1-2):

[0028]

[0029] Where: Q' is the corrected blood pump flow calculated by the host of the online calibration device; c t The blood temperature collected by the temperature measuring element is obtained by looking up Table 2, which corresponds to the sound velocity of the ultrasonic signal propagating in human blood at that temperature; k is the flow velocity correction coefficient;

[0030] When the blood temperature collected by the temperature measuring element is between the two integer temperature points in Table 2, the corresponding ultrasonic signal propagation speed in human blood can be calculated by interpolation method, specifically the algorithm formula (1-3);

[0031]

[0032] Where: w t Collect blood temperature for temperature measurement element; c t To collect blood temperature w according to the temperature measuring element t The sound velocity of the ultrasonic signal in human blood is calculated by interpolating the data in Table 2; w1 is the value of w in Table 2. t The lower adjacent integer temperature point; w2 is the lower adjacent integer temperature point in Table 2. t The highest adjacent integer temperature point; c1 is the human blood sound velocity value corresponding to temperature w1 in Table 2; c2 is the human blood sound velocity value corresponding to temperature w2 in Table 2;

[0033] Table 2 The corresponding relationship between the propagation speed of ultrasonic signals in human blood and temperature

[0034]

[0035] In order to improve the accuracy of flow measurement data, the flow rate correction coefficient k in the flow data algorithm was analyzed. Combined with the actual situation of calibrating the extracorporeal membrane oxygenation system, the flow rate correction coefficients for different flow rates and different flow field distributions when using adult extracorporeal circulation circuits to treat patients were determined. The following compensation coefficients were obtained to reflect this correction, respectively according to the Reynolds coefficient R e <2300、Reynolds coefficient R e >4000 and Reynolds number 2300<R e <4000, adjust the flow rate correction coefficient k in three cases;

[0036] Therefore, in formula (1-2), the velocity correction coefficient k is defined as the linear average velocity v and the surface average velocity v m The velocity correction coefficient is related to the flow state of the measured fluid, and the velocity correction coefficient k depends on the Reynolds number Re of the fluid in the pipeline. ， Specifically:

[0037] When the fluid is laminar (Reynolds coefficient R e <2300):

[0038]

[0039] When the fluid becomes turbulent (Reynolds coefficient R e >4000):

[0040]

[0041] When the fluid flow state is between laminar flow and turbulent flow (i.e. Reynolds coefficient 2300<R e <4000):

[0042] k=1.119-0.0111gR e (1-6)

[0043] When calibrating the extracorporeal membrane oxygenation system online, the measurement medium is human blood, and the Reynolds coefficient of the extracorporeal circulation circuit at different flow rates is calculated and analyzed. The Reynolds coefficient of the liquid in the circuit is calculated using formula (1-7);

[0044] R e =v m d / r (1-7)

[0045] Where: R e is the Reynolds coefficient; v m is the average flow velocity in the pipeline; d is the pipeline diameter; r is the liquid kinematic viscosity coefficient;

[0046] Liquid volume flow rate Q in the pipeline, average flow velocity v m And the pipe cross-sectional area S has the following relationship:

[0047]

[0048] Substituting formula (1-8) into formula (1-7) yields:

[0049] R e =v m d / r=4Q / (πdr) (1-9)

[0050] It is known that the blood pump flow rate of the extracorporeal membrane oxygenation system to be calibrated ranges from 500 to 8000 mL / min, the inner diameter of the adult extracorporeal circulation tubing is 3 / 8", and the human blood viscosity coefficient is 5.90×10 -6 m 2 / s, substituting the above conditions into formula (1-9) for calculation and analysis, when online calibrating the blood pump flow of the extracorporeal membrane oxygenation system, the measuring medium in the circulation pipeline is human blood. When the blood pump flow is in the range of 500-6130mL / min, the liquid flow state is laminar flow; in the range of 6130-8000mL / min, the liquid flow state is between laminar flow and turbulent flow;

[0051] That is, in the internal algorithm of the blood pump flow of the host online calibration device, the blood pump flow is in the range of 500-6130 mL / min, and the flow rate correction coefficient k in formula (1-2) is 4 / 3; the blood pump flow is in the range of 6130-8000 mL / min, and the flow rate correction coefficient k in formula (1-2) is 1.119-0.0111gR e ;

[0052] After the host of the online calibration device calculates the blood pump flow calibration data according to the above internal algorithm, it is displayed on the touch screen of the host of the online calibration device in the form of waveform and data according to the settings of the calibrator;

[0053] Step 4: The software automatically calculates the relative indication error of the blood pump flow and determines whether it exceeds the tolerance

[0054] After the calibrator manually inputs the blood pump flow monitoring value of the extracorporeal membrane oxygenation system to be calibrated through the touch screen of the online calibration device host, the online calibration device host automatically calculates the relative indication error of the blood pump flow. When the absolute value of the relative indication error exceeds the preset error threshold, the blood pump flow calibration result is out of tolerance. At this time, the measurement software of the online calibration device host pops up a prompt box to warn that the blood pump flow is out of tolerance, prompting the extracorporeal membrane oxygenation system user to check the working status of the extracorporeal membrane oxygenation system. The blood pump flow error threshold is usually set to 10%;

[0055] The relative indication error of the calibrated extracorporeal membrane oxygenation system blood pump flow rate is calculated using formula (1-10):

[0056]

[0057] Where: Δ Q is the relative indication error of the extracorporeal membrane oxygenation system blood pump flow rate; Q' is the blood pump flow rate value corrected by the internal algorithm of the online calibration device host; Q0 is the calibrated extracorporeal membrane oxygenation system blood pump flow rate monitoring value input through the online calibration device host;

[0058] Step 5: Start the blood pump speed calibration function to collect data through the Hall sensor

[0059] The calibrator starts the blood pump speed calibration program by clicking on the touch screen of the online calibration device host. The online calibration device host transmits the start blood pump speed calibration instruction to the Hall sensor through the second data line interface of the data line. When the magnetic pole on the rotating body in the blood pump head of the extracorporeal membrane oxygenation system being calibrated passes the Hall sensor of the online calibration device, the free electrons in the direct current of the Hall element in the sensor that move in a direction under the action of the magnetic field of the magnetic pole are deflected by the Lorentz force generated by the Hall effect, generating a voltage pulse signal. This voltage is called the Hall voltage, and the voltage value is calculated by formula (1-11):

[0060]

[0061] Among them: U H is the Hall voltage; R H is the Hall resistance value in the Hall element; I is the DC current value in the Hall element; B is the magnetic field strength value of the magnetic pole in the blood pump head of the calibrated extracorporeal membrane oxygenation system; h is the thickness of the Hall element;

[0062] Different models of extracorporeal membrane oxygenation (ECMO) blood pump heads have different magnetic field strengths at the internal magnetic poles. Table 3 shows the magnetic field strength values ​​for the magnetic pole positions of three mainstream ECMO blood pump heads. When the magnetic poles in the ECMO blood pump heads of different models rotate past the Hall effect sensors of the online calibration device, different Hall effect voltage values ​​are generated. The present invention accurately measures and calibrates the speed of the ECMO blood pump heads of different models by setting different voltage thresholds in the internal algorithm of the online calibration device's main blood pump speed for different ECMO systems.

[0063] Table 3 Magnetic field strength of the magnetic pole positions of the blood pump heads of three mainstream models of extracorporeal membrane oxygenation systems

[0064]

[0065] During the online calibration of the blood pump speed, when the Hall sensor receives the calibration start instruction from the online calibration device host through the data line, the timing unit in the Hall sensor starts timing and the register is cleared. When the voltage detection circuit detects that the Hall element generates a Hall voltage pulse signal and the voltage value U HWhen the voltage is greater than the voltage threshold U0 set in the algorithm for this model of extracorporeal membrane oxygenation system, the number of voltage pulses M in the register is increased by 1; the Hall sensor transmits the number of Hall voltage pulse signals M greater than the voltage threshold U0 recorded in the unit time register to the host of the online calibration device via the data line of the second data line interface;

[0066] Step 6: The online calibration device host calculates the blood pump speed data based on the internal algorithm

[0067] The host of the online calibration device calculates the blood pump speed data of the calibrated extracorporeal membrane oxygenation system through the internal algorithm formula (1-12);

[0068]

[0069] Where: n is the calibration result of the blood pump speed; t m The timing unit records the calibration time; M is the number of Hall voltage pulse signals exceeding the voltage threshold recorded in the register during the calibration time;

[0070] After the main unit of the online calibration device calculates the calibration data of the blood pump speed according to the above internal algorithm, it is displayed on the touch screen of the main unit of the online calibration device in the form of waveform and data according to the settings of the calibrator;

[0071] Step 7: The software automatically calculates the relative error of the blood pump speed indication and determines whether it exceeds the tolerance.

[0072] After the calibrator manually inputs the blood pump speed monitoring value of the extracorporeal membrane oxygenation system to be calibrated through the touch screen of the online calibration device host, the online calibration device host automatically calculates the relative indication error of the blood pump speed. When the absolute value of the relative indication error exceeds the preset error threshold, the blood pump speed calibration result is out of tolerance. At this time, the measurement software of the online calibration device host pops up a prompt box to warn that the blood pump speed is out of tolerance, prompting the extracorporeal membrane oxygenation system user to check the working status of the extracorporeal membrane oxygenation system. The blood pump speed error threshold is usually set to 5%;

[0073] The relative indication error of the blood pump speed of the calibrated extracorporeal membrane oxygenation system is calculated using formula (1-13):

[0074]

[0075] Where: Δ n is the relative indication error of the extracorporeal membrane oxygenation system blood pump speed; n is the blood pump speed value calculated by the internal algorithm of the online calibration device host; n0 is the calibrated extracorporeal membrane oxygenation system blood pump speed monitoring value input through the online calibration device host.

[0076] Furthermore, in the blood pump flow data processing, the multiple transmission and reception time difference data of ultrasound are combined and processed to extend the ultrasound sound path, reduce the time difference measurement error, and improve the blood pump flow measurement accuracy;

[0077] If the time required for N downstream ultrasonic signals to be transmitted and received is T1, which includes the sum of N inherent delay times τ0 and the sum of the single downstream propagation time t1 of N ultrasonic signals in the measurement medium human blood, that is, formula (1-14)

[0078] T1=N·τ0+N·t1 (1-14)

[0079] The time T2 required from the transmission to the reception of N countercurrent ultrasonic signals is expressed by formula (1-15):

[0080] T2=N·τ0+N·t2 (1-15)

[0081] At this time, the time difference formula of ultrasonic signal propagation upstream and downstream is (1-16)

[0082]

[0083] The number of repeated acquisitions N was set to different values ​​according to the actual calibration blood pump flow range. The corresponding relationship between the number of repeated acquisitions and the blood pump flow range in data processing is shown in Table 1. By adopting this data processing algorithm, the measurement sound range of the ultrasonic measurement signal during online calibration of the blood pump flow is extended. The measured small time quantities t1 and t2 can be converted into larger time quantities T1 and T2 that are easier to measure accurately, thereby improving the accuracy of blood pump flow measurement.

[0084] The objectives of the present invention and the technical problems solved therein are achieved by adopting the following technical solutions. The present invention provides an online calibration device for an extracorporeal membrane oxygenation system, which primarily comprises: an online calibration device host, a transit-time flow sensor, a Hall effect sensor, and a data cable. The Hall effect sensor is connected to the online calibration device host via the data cable. One end of the transit-time flow sensor is connected to the online calibration device host via the data cable. The other end of the transit-time flow sensor is connected to the extracorporeal circulation perfusion line of the extracorporeal membrane oxygenation system. One end of the extracorporeal membrane oxygenation system blood pump head is connected to the patient via the extracorporeal circulation perfusion line of the extracorporeal membrane oxygenation system. Another end of the extracorporeal membrane oxygenation system blood pump head is connected to the patient via the extracorporeal circulation drainage line of the extracorporeal membrane oxygenation system.

[0085] Furthermore, the time-difference flow sensor includes a flow sensor housing and a first ultrasonic transmitter-receiver unit, a second ultrasonic transmitter-receiver unit, a temperature measuring element, a pipeline slot, and a first data line interface arranged in the flow sensor housing. The first ultrasonic transmitter-receiver unit and the second ultrasonic transmitter-receiver unit are relatively arranged at both ends of the pipeline slot. The angle between the geometric center line of the first ultrasonic transmitter-receiver unit and the second ultrasonic transmitter-receiver unit and the center line of the pipeline slot is α, and the range of α is 40° to 50°. The temperature measuring element is located on the side wall of the pipeline slot, and the time-difference flow sensor is connected to the data line in sequence through the first data line interface.

[0086] Furthermore, the Hall sensor includes a sensor housing and a Hall element, a DC power supply circuit, a register, a voltage detection circuit and a second data line interface arranged in the sensor housing, wherein the voltage detection circuit is connected to the Hall element and is used to detect the voltage value of the Hall voltage generated by the Hall element under the action of an external magnetic field, the register and the timing unit are connected to the voltage detection circuit, and the Hall sensor is connected to the online calibration device host through the second data line interface and the data line in sequence.

[0087] Furthermore, the extracorporeal membrane oxygenation system blood pump head includes: a housing and a rotating shaft, a rotating body and a magnetic pole arranged in the housing, wherein multiple magnetic poles are evenly distributed on the edge of the rotating body, the rotating shaft is arranged on the central axis inside the housing, and the rotating body is installed at the bottom of the housing with the rotating shaft as the axis. When clinically treating a patient, when the rotating body in the extracorporeal membrane oxygenation system blood pump head rotates at high speed with the rotating shaft as the axis, the magnetic pole rotates at high speed with the rotating body, and the Hall sensor is arranged at a position perpendicular to the rotation plane of the rotating body and close to the edge of the upper surface of the housing. When the magnetic pole on the rotating body in the calibrated extracorporeal membrane oxygenation system blood pump head approaches the detection surface of the Hall element during rotation, the Hall element generates a Hall voltage signal under the action of the magnetic field of the magnetic pole.

[0088] Compared with the prior art, the present invention has obvious advantages and beneficial effects. It has at least the following advantages:

[0089] Currently, there is no calibration device available for online calibration of extracorporeal membrane oxygenation systems, leaving routine metrological calibration and clinical quality control of blood pump flow and speed largely unproven. This invention, through hardware design and development of targeted data processing algorithms, enables real-time data acquisition and calibration of key extracorporeal membrane oxygenation system parameters, blood pump flow and speed, during patient treatment. This addresses the challenge of developing online calibration equipment for extracorporeal membrane oxygenation systems, providing a technical and equipment foundation for metrological calibration and clinical quality control.

[0090] 2. This invention utilizes the principle of time-of-flight ultrasonic flow measurement to effectively address the issue of online blood pump flow calibration during extracorporeal membrane oxygenation (ECMO) system treatment. This approach, combined with the actual flow state of fluid in the circulation circuit, conducts an in-depth analysis of the flow rate correction factor k used in the blood pump flow algorithm. Based on the actual conditions of ECMO system calibration, this method determines the flow rate correction factor for different flow rates and flow field distributions when clinically treating adult patients with ECMO circuits. This significantly improves the accuracy of measurement data, making the blood pump flow calibration data more clinically relevant.

[0091] 3. The present invention adds a sound velocity temperature correction to the blood pump flow data processing algorithm. By integrating a table of the correspondence between the sound velocity and temperature of human blood into the algorithm, the temperature measuring element in the time-difference flow sensor collects the blood temperature in the circulation pipeline in real time, and uses interpolation to calculate the accurate sound velocity value at the current temperature, effectively reducing the impact of temperature fluctuations on blood pump flow measurement and further improving the accuracy of blood pump flow calibration data.

[0092] 4. The present invention's blood pump flow data acquisition program utilizes multiple transmission and reception of ultrasonic signals to extend the ultrasonic sound path, significantly reducing time-of-flight measurement errors and improving the accuracy of blood pump flow measurements at low flow rates. The number of repeated acquisitions is set based on the measured blood pump flow range, ensuring the reliability of calibration data under varying flow conditions.

[0093] 5. This invention utilizes a Hall effect sensor to generate Hall effect voltage pulse signals by detecting the rotation of the magnetic poles on the rotating element in the blood pump head, thereby enabling online calibration of the blood pump speed during patient treatment. This effectively solves the problem of the rotating element being invisible when the blood pump head is filled with patient blood during online calibration, making conventional optical non-contact speed measurement methods such as stroboscopic and laser marking methods unsuitable for online calibration of the blood pump speed in extracorporeal membrane oxygenation systems.

[0094] This invention achieves real-time data collection and calibration of key parameters of the extracorporeal membrane oxygenation system, including blood pump flow rate and blood pump speed, during the patient treatment phase. This method determines the flow rate correction coefficient for different flow rates and flow field distributions when treating adult patients using an extracorporeal circulation circuit. This significantly improves the accuracy of measurement data, making the blood pump flow calibration data more clinically relevant and enhancing the accuracy of blood pump flow measurement at low flow points. This invention also enables online calibration of the blood pump speed during the patient treatment phase. This invention effectively addresses the problem of the blood pump head filling with patient blood during online calibration, rendering the rotating body in the pump head invisible and making conventional optical non-contact speed measurement methods, such as stroboscopic and laser marking methods, unsuitable for online calibration of the blood pump speed in extracorporeal membrane oxygenation systems. The above description is merely an overview of the technical solution of the present invention. To better understand the technical approach of the present invention, which can be implemented in accordance with the present description, and to make the above and other objects, features, and advantages of the present invention more readily apparent, the following describes a preferred embodiment in detail, accompanied by accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0095] Figure 1A This is a diagram of the blood pump head before it is filled with blood.

[0096] Figure 1B This is a diagram of the blood pump head filling with patient blood during the use stage.

[0097] Figure 2 It is a schematic diagram of the structure of the online calibration device of the extracorporeal membrane oxygenation system of the present invention.

[0098] Figure 3 This is a schematic diagram of the connection of a calibration system when using the present invention to calibrate an extracorporeal membrane oxygenation system online.

[0099] Figure 4 This is a schematic diagram of the relative positions of the Hall sensor and the blood pump head of the present invention.

[0100] Figure 5 It is a schematic structural diagram of the time difference flow sensor of the present invention.

[0101] Figure 6 It is a schematic structural diagram of the Hall sensor of the present invention.

[0102] Figure 7 This is a control flow chart and data transmission diagram of the online calibration device of the present invention.

[0103] Figure 8 This is a working principle diagram of the Z-type time-difference flow sensor of the present invention.

[0104] in:

[0105] 1: Online calibration device host

[0106] 2: Time difference flow sensor

[0107] 201: Flow sensor housing 202: First ultrasonic transmitting and receiving unit

[0108] 203: Second ultrasonic transmitting and receiving unit 204: Temperature measuring element

[0109] 205: Pipeline slot 206: First data line interface

[0110] 3: Hall sensor

[0111] 301: sensor housing 302: Hall element

[0112] 303: DC power supply circuit 304: Register

[0113] 305: Voltage detection circuit 306: Second data line interface

[0114] 307: Timing Unit

[0115] 4: Data cable

[0116] 5: Extracorporeal membrane oxygenation system blood pump head

[0117] 501: Shell

[0118] 502: Rotation axis

[0119] 503: Rotating body

[0120] 504: Magnetic Pole

[0121] 6: Extracorporeal membrane oxygenation system extracorporeal circulation perfusion circuit

[0122] 7: Extracorporeal membrane oxygenation system extracorporeal circulation drainage circuit

[0123] 8: Patient DETAILED DESCRIPTION

[0124] To further illustrate the technical means and effectiveness of the present invention in achieving its intended purpose, the following, in conjunction with the accompanying drawings and preferred embodiments, describes in detail an online calibration method and device for an extracorporeal membrane oxygenation system according to the present invention, including its specific implementation, structure, method, steps, features, and effectiveness.

[0125] The schematic diagram of the extracorporeal membrane oxygenation system structure is developed to realize the online calibration function of the key parameters of blood pump flow and blood pump speed during the treatment of patients with extracorporeal membrane oxygenation system. Figure 2As shown. The preferred embodiment of the present invention is an online calibration device for an extracorporeal membrane oxygenation system, which mainly includes: an online calibration device host 1, a time difference flow sensor 2, a Hall sensor 3 and a data line 4. When online calibration is performed, Figure 3 As shown, Hall effect sensor 3 is connected to online calibration device host 1 via data cable 4. Transit time flow sensor 2 is connected to online calibration device host 1 via data cable 4 at one end, and connected to extracorporeal membrane oxygenation system extracorporeal circulation perfusion line 6 at the other end. Extracorporeal membrane oxygenation system blood pump head 5 is connected to patient 8 via extracorporeal membrane oxygenation system extracorporeal circulation perfusion line 6 at one end, and connected to patient 8 via extracorporeal membrane oxygenation system extracorporeal circulation drainage line 7 at another end.

[0126] like Figure 5 As shown, the transit time flow sensor 2 includes a flow sensor housing 201 and a first ultrasonic transmitter-receiver unit 202, a second ultrasonic transmitter-receiver unit 203, a temperature measuring element 204, a pipe slot 205, and a first data line interface 206 arranged in the flow sensor housing 201. The first ultrasonic transmitter-receiver unit 202 and the second ultrasonic transmitter-receiver unit 203 are arranged at opposite ends of the pipe slot 205. The angle α between the geometric center line connecting the first ultrasonic transmitter-receiver unit 202 and the second ultrasonic transmitter-receiver unit 203 and the center line of the pipe slot 205 is 40° to 50°. The temperature measuring element 204 is located on the side wall of the pipe slot 205. The transit time flow sensor 2 is connected to the data line 4 in sequence through the first data line interface 206.

[0127] During online calibration of the extracorporeal membrane oxygenation system's blood pump flow rate, the transit-time flow sensor 2 (online calibration device) is clamped into the extracorporeal circulation perfusion tubing 6 of the extracorporeal membrane oxygenation system being calibrated via the tubing clamping slot 205 on the sensor, ensuring that the tubing wall closely adheres to the sidewalls of the tubing clamping slot 205. To ensure stable fluid flow in the tubing, the tubing in which the transit-time flow sensor 2 is mounted should be straight and free of height differences, with at least 10 cm of straight tubing reserved both before and after the transit-time flow sensor 2.

[0128] The first ultrasound transmitting and receiving unit 202 transmits an ultrasound signal to the second ultrasound transmitting and receiving unit 203 and starts timing. The ultrasound signal propagates through the patient's blood flowing in the extracorporeal circulation perfusion tube and is received by the second ultrasound transmitting and receiving unit 203. The timing is stopped after the second ultrasound transmitting and receiving unit 203 receives the ultrasound signal, and the downstream propagation time of the ultrasound signal is obtained. The second ultrasound transmitting and receiving unit 203 then transmits an ultrasound signal to the first ultrasound transmitting and receiving unit 202 and starts timing. The ultrasound signal propagates through the patient's blood flowing in the extracorporeal circulation perfusion tube and is received by the first ultrasound transmitting and receiving unit 202. The timing is stopped after the first ultrasound transmitting and receiving unit 202 receives the ultrasound signal, and the upstream propagation time of the ultrasound signal is obtained. The temperature measuring element 204 contacts the extracorporeal circulation perfusion tubing of the extracorporeal membrane oxygenation system being calibrated to collect the patient's blood temperature. The time-of-flight flow sensor 2 transmits the ultrasonic signal downstream propagation time, the ultrasonic signal upstream propagation time, and the blood temperature data to the online calibration device host 1 via the first data line interface 206 and the data line 4. The blood pump flow calibration data is calculated using an internal algorithm and displayed as waveforms and data according to the settings set by the calibrator. After the calibrator manually enters the blood pump flow monitoring value of the extracorporeal membrane oxygenation system being calibrated through the touch screen of the online calibration device host 1, the online calibration device host 1 automatically calculates the relative indication error of the blood pump flow. When the relative indication error exceeds a preset error threshold, the measurement software of the online calibration device host 1 pops up a prompt box to warn that the blood pump flow is out of tolerance, prompting the user of the extracorporeal membrane oxygenation system to check the operating status of the extracorporeal membrane oxygenation system.

[0129] The time-difference flow sensor 2 transmits ultrasonic signals to the blood flowing in the extracorporeal circulation circuit of the extracorporeal membrane oxygenation system via a first ultrasonic transmitting and receiving unit 202 and a second ultrasonic transmitting and receiving unit 203, respectively, to obtain time difference data of the signals propagating downstream and upstream in the blood. The sensor also collects blood temperature data via an internal temperature measuring element 204. The collected time difference data of the ultrasonic signals propagating downstream and upstream, as well as the blood temperature data, are transmitted to the online calibration device host 1 via a first data interface 206 and a data line 4. The online calibration device host 1 calculates the calibration result of the extracorporeal membrane oxygenation system's blood pump flow value based on the received time difference data of the ultrasonic signals propagating downstream and upstream, using a developed internal blood pump flow algorithm. The result is displayed on the touch screen of the online calibration device host 1 in the form of data and waveforms. During the calculation process, the speed of sound in the algorithm is corrected based on the blood temperature data collected by the sensor, thereby eliminating the influence of temperature fluctuations on the calibration result and improving the accuracy of the calibration data.

[0130] like Figure 6As shown, the Hall sensor 3 includes a sensor housing 301 and a Hall element 302, a DC power supply circuit 303, a register 304, a voltage detection circuit 305 and a second data line interface 306 arranged in the sensor housing 301, wherein the voltage detection circuit 305 is connected to the Hall element 302 and is used to detect the voltage value of the Hall voltage generated by the Hall element 302 under the action of an external magnetic field, the register 304 and the timing unit 307 are connected to the voltage detection circuit 305, and the Hall sensor 3 is connected to the online calibration device host 1 through the second data line interface 306 and the data line 4 in sequence.

[0131] like Figure 4 As shown, the blood pump head 5 of the extracorporeal membrane oxygenation system includes: a housing 501 and a rotating shaft 502, a rotating body 503 and a magnetic pole 504 arranged in the housing 501. Among them, multiple magnetic poles 504 are evenly distributed on the edge of the rotating body 503. The rotating shaft 502 is arranged on the central axis inside the housing 501. The rotating body 503 is installed at the bottom of the housing 501 with the rotating shaft 502 as the axis. When clinically treating a patient, when the rotating body 503 in the blood pump head 5 of the extracorporeal membrane oxygenation system rotates at high speed with the rotating shaft 502 as the axis, the magnetic pole 504 rotates at high speed along with the rotating body 503.

[0132] When online calibrating the blood pump speed of the extracorporeal membrane oxygenation system, fix the Hall sensor 3 of the online calibration device on the measuring bracket. By adjusting the bracket, the measuring surface of the Hall sensor 3 is lightly touched to the upper surface of the blood pump head 5 of the extracorporeal membrane oxygenation system, and ensure that the axis of the Hall sensor 3 is perpendicular to the rotation plane of the rotating body 503 in the blood pump head 5. Several magnetic poles 504 are evenly distributed on the edge of the rotating body 503 in the blood pump head 5 of the extracorporeal membrane oxygenation system. When the rotating body 503 in the blood pump head 5 rotates at high speed during patient treatment, the magnetic poles 504 rotate with the rotating body 503 at high speed. The Hall sensor 3 of the online calibration device is arranged at a position perpendicular to the rotation plane of the rotating body 503 in the blood pump head 5 and close to the edge of the upper surface of the housing 501. Figure 4 As shown, whenever the magnetic pole 504 approaches the Hall sensor 3, due to the Hall effect, the free electrons in the Hall element 302 of the Hall sensor 3 are deflected under the action of the magnetic field of the magnetic pole 504 to generate a Hall voltage pulse signal. When the voltage of the pulse signal is greater than the preset voltage threshold, the counter in the register 304 will record the voltage pulse signal. The online calibration device host 1 calculates the calibration result of the blood pump speed value of the calibrated extracorporeal membrane oxygenation system based on the number of pulse signals greater than the voltage threshold detected by the Hall sensor 3 per unit time through the developed blood pump speed internal algorithm, and displays the result on the touch screen of the online calibration device host 1 in the form of data and waveform.

[0133] The DC power supply circuit 303 is used to generate a DC current of a certain intensity for the Hall element 302. When the magnetic pole on the rotating body 503 in the pump head 5 of the extracorporeal membrane oxygenation system being calibrated approaches the detection surface of the Hall element 302 during rotation, the free electrons in the DC current generated by the DC power supply circuit 303 in the Hall element 302 undergo Hall effect motion trajectory deflection under the influence of the magnetic field of the magnetic pole 504, generating a voltage signal of a certain intensity, namely the Hall voltage, in a direction perpendicular to the current. The voltage detection circuit 305 is connected to the Hall element 302 and is used to detect the voltage value of the Hall voltage generated by the Hall element 302 under the influence of the external magnetic field. The register 304 and the timing unit 307 are connected to the voltage detection circuit. When online calibration of the extracorporeal membrane oxygenation system blood pump speed begins, the timing unit 307 starts timing, the register 304 is reset, and when the voltage detection circuit detects that the Hall element 302 has generated a voltage under the influence of the external magnetic field, the timing unit 307 starts timing and the register 304 is reset. When the generated Hall voltage value exceeds the internal algorithm voltage threshold, the number of voltage signal pulses in register 304 is increased by 1. When the calibration time recorded by the timing unit 307 reaches a preset time length, the Hall sensor 3 transmits the number of voltage pulse signals recorded by register 304 during the calibration process to the online calibration device host 1 via the second data line interface 306 and the data line 4. The online calibration device host 1 calculates the blood pump speed calibration data using the internal blood pump speed algorithm and displays it in waveform and data according to the settings of the calibrator. After the calibrator manually enters the blood pump speed monitoring value of the extracorporeal membrane oxygenation system to be calibrated through the touch screen of the online calibration device host 1, the online calibration device host 1 automatically calculates the relative indication error of the blood pump speed. When the relative indication error exceeds the preset error threshold, the measurement software of the online calibration device host 1 pops up a prompt box to warn that the blood pump speed is out of tolerance, prompting the user of the extracorporeal membrane oxygenation system to check the working status of the extracorporeal membrane oxygenation system.

[0134] The control process and data transmission diagram of the online calibration device of the extracorporeal membrane oxygenation system of the present invention are as follows: Figure 7As shown, the online calibration device host 1 sends instructions to control the transit time flow sensor 2 for collecting blood pump flow data, and also sends instructions to control the Hall effect sensor 3 for collecting blood pump speed data. During actual calibration of the extracorporeal membrane oxygenation system's blood pump flow, the transit time flow sensor 2 collects the time difference between the downstream and upstream propagation of the ultrasonic signal in the extracorporeal circulation perfusion tubing 6 of the extracorporeal membrane oxygenation system being calibrated, as well as blood temperature data, and transmits it to the online calibration device host 1 via the first data line interface 206 and the data line 4. The online calibration device host 1 calculates the blood pump flow calibration result according to a stored internal blood pump flow algorithm and displays it in the form of waveforms and data. The calibrator inputs the monitored blood pump flow value of the extracorporeal membrane oxygenation system being calibrated via the touch screen of the online calibration device host 1. The online calibration device host 1 automatically calculates the relative indication error of the blood pump flow. When the relative indication error of the blood pump flow exceeds a preset error threshold, the measurement software of the online calibration device host 1 displays a prompt box warning that the blood pump flow is out of tolerance, prompting the user of the extracorporeal membrane oxygenation system to check the operating status of the extracorporeal membrane oxygenation system.

[0135] During actual calibration of the blood pump speed of the extracorporeal membrane oxygenation system, the Hall sensor 3 collects the number of times per unit time that the magnetic pole 504 in the pump head 5 of the extracorporeal membrane oxygenation system to be calibrated causes the Hall element 302 in the Hall sensor 3 to generate a voltage pulse signal exceeding a voltage threshold, and transmits the information to the online calibration device host 1 via the second data line interface 306 and the data line 4. The online calibration device host 1 calculates the blood pump speed calibration result according to a stored internal blood pump speed algorithm and displays the result in waveform and data form. The calibrator inputs the blood pump speed monitoring value of the extracorporeal membrane oxygenation system to be calibrated through the touch screen of the online calibration device host 1. The online calibration device host 1 automatically calculates the relative indication error of the blood pump speed. When the relative indication error of the blood pump speed exceeds a preset error threshold, the measurement software of the online calibration device host 1 pops up a prompt box to warn that the blood pump speed is out of tolerance, prompting the user of the extracorporeal membrane oxygenation system to check the operating status of the extracorporeal membrane oxygenation system.

[0136] According to the present invention, an online calibration method for an extracorporeal membrane oxygenation system mainly includes the following steps:

[0137] Step 1: Connect the online calibration device to the extracorporeal membrane oxygenation system circuit to be calibrated

[0138] Before online calibration of the extracorporeal membrane oxygenation system, clamp the transit time flow sensor 2 of the online calibration device to the extracorporeal circulation perfusion pipeline 6 of the extracorporeal membrane oxygenation system to be calibrated through the pipeline clamping slot 205. To ensure stable liquid flow in the pipeline, the pipeline where the transit time flow sensor 2 is installed should be straight without any height difference, and at least 10 cm of straight pipe section should be reserved before and after the installation position of the transit time flow sensor 2.

[0139] Fix the Hall sensor 3 of the online calibration device on the measuring bracket. Adjust the bracket so that the measuring surface of the Hall sensor 3 touches the upper surface of the blood pump head 5 of the extracorporeal membrane oxygenation system, and ensure that the axis of the Hall sensor 3 is perpendicular to the rotation plane of the rotating body 503.

[0140] Step 2: Start the blood pump flow calibration function and collect data through the time difference flow sensor 2

[0141] The calibrator starts the blood pump flow calibration procedure by clicking on the touch screen of the online calibration device host 1.

[0142] The host 1 of the online calibration device transmits the blood pump flow calibration start instruction to the time difference flow sensor 2 through the first data line interface 206 of the data line 4. After the time difference flow sensor 2 receives the instruction, the first ultrasonic transmitting and receiving unit 202 transmits an ultrasonic signal to the second ultrasonic transmitting and receiving unit 203 and starts timing. The ultrasonic signal is transmitted through the patient's blood flowing in the extracorporeal circulation perfusion tube and is received by the second ultrasonic transmitting and receiving unit 203. After the second ultrasonic transmitting and receiving unit 203 receives the ultrasonic signal, the timing is stopped to obtain the ultrasonic signal downstream propagation time. After that, the second ultrasonic transmitting and receiving unit 203 transmits an ultrasonic signal to the first ultrasonic transmitting and receiving unit 202 and starts timing. The ultrasonic signal is transmitted through the patient's blood flowing in the extracorporeal circulation perfusion tube and is received by the second ultrasonic transmitting and receiving unit 203. The patient's blood flowing in the extracorporeal circulation perfusion tube is received by the first ultrasonic transmitting and receiving unit 202 after propagation. After the first ultrasonic transmitting and receiving unit 202 receives the ultrasonic signal, the timing is stopped to obtain the reverse flow propagation time of the ultrasonic signal. When designing the blood pump flow data acquisition program, the ultrasonic signal is transmitted and received multiple times to extend the ultrasonic sound path, thereby reducing the time difference measurement error, thereby improving the measurement accuracy of the blood pump flow at a small flow point of the present invention. Specifically, different repeated acquisition times are set according to the measured blood pump flow range. The corresponding relationship between the repeated acquisition times and the blood pump flow is shown in Table 1. The time difference flow sensor 2 records N times of ultrasonic signal downstream propagation time and N times of ultrasonic signal reverse flow propagation time measurement data respectively;

[0143] Table 1 Correspondence between the number of repeated acquisitions and the blood pump flow range in data processing

[0144]

[0145] At the same time, the temperature measuring element 204 in the transit time flow sensor 2 measures the blood temperature data in the extracorporeal circulation perfusion circuit 6 of the calibrated extracorporeal membrane oxygenation system;

[0146] The time difference flow sensor 2 transmits the collected N ultrasonic signal downstream propagation time, N ultrasonic signal upstream propagation time measurement data and blood temperature data to the online calibration device host 1 through the first data line interface 206 and the data line 4;

[0147] Step 3: The online calibration device host 1 calculates the blood pump flow data according to the internal algorithm

[0148] The time difference flow sensor 2 measures the difference in propagation time between the ultrasonic signal in the upstream and downstream directions, and the relationship between the measured difference in propagation time between the ultrasonic signal in the downstream and upstream directions and the flow velocity of the fluid to be measured is used to calculate the flow velocity of the measuring medium in the pipeline, and then the measuring medium flow is calculated in combination with the cross-sectional area of ​​the pipeline. When the blood pump flow is actually calibrated, the main unit 1 of the online calibration device calculates the blood pump flow data of the extracorporeal membrane oxygenation system to be calibrated using the internal algorithm formula (1-1) and formula (1-2);

[0149] The uncorrected blood pump flow is calculated using formula (1-1):

[0150]

[0151] Where: Q is the uncorrected blood pump flow rate calculated by the main unit of the online calibration device; c is the sound velocity of the ultrasonic signal in human blood; d is the inner diameter of the extracorporeal perfusion pipe of the extracorporeal membrane oxygenation system; T2 is the Nth reverse flow propagation time of the ultrasonic signal; T1 is the Nth downstream propagation time of the ultrasonic signal; N is the number of repeated transmissions and receptions of the ultrasonic signal, which can be obtained by looking up Table 1; α is the angle between the line connecting the first ultrasonic transmitting and receiving unit 202 and the second ultrasonic transmitting and receiving unit 203 in the sensor and the geometric centerline of the pipe;

[0152] The temperature measurement element 204 in the time difference flow sensor 2 collects the blood temperature, and the propagation speed of the ultrasonic signal in the human blood in the algorithm formula (1-1) is corrected for temperature. After adding the flow rate correction coefficient to the formula (1-1) according to the blood flow state, the blood pump flow rate after the above algorithm correction can be calculated by (1-2):

[0153]

[0154] Where: Q' is the corrected blood pump flow calculated by the host of the online calibration device; c t The blood temperature collected by the temperature measuring element (204) is obtained by looking up Table 2 corresponding to the sound velocity of the ultrasonic signal propagating in human blood at the temperature; k is a flow velocity correction coefficient;

[0155] When the blood temperature collected by the temperature measuring element (204) is between two integer temperature points in Table 2, the corresponding sound velocity of the ultrasonic signal propagating in human blood is calculated by interpolation, specifically, the algorithm formula (1-3);

[0156]

[0157] Where: w t The temperature measuring element (204) collects the blood temperature; tTo collect blood temperature w according to the temperature measuring element (204) t The sound velocity of the ultrasonic signal in human blood is calculated by interpolating the data in Table 2; w1 is the value of w in Table 2. t The lower adjacent integer temperature point; w2 is the lower adjacent integer temperature point in Table 2. t The highest adjacent integer temperature point; c1 is the human blood sound velocity value corresponding to temperature w1 in Table 2; c2 is the human blood sound velocity value corresponding to temperature w2 in Table 2;

[0158] Table 2 The corresponding relationship between the propagation speed of ultrasonic signals in human blood and temperature

[0159]

[0160] The velocity correction coefficient k in formula (1-2) is defined as the linear average velocity v and the surface average velocity v m The velocity correction coefficient is related to the flow state of the measured fluid. The velocity correction coefficient k depends on the Reynolds number Re of the fluid in the pipeline. Specifically:

[0161] When the fluid is laminar (Reynolds coefficient R e <2300):

[0162]

[0163] When the fluid becomes turbulent (Reynolds coefficient R e >4000):

[0164]

[0165] When the fluid flow state is between laminar flow and turbulent flow (i.e. Reynolds coefficient 2300<R e <4000):

[0166] k=1.119-0.0111gR e (1-6)

[0167] When calibrating the extracorporeal membrane oxygenation system online, the measurement medium is human blood, and the Reynolds coefficient of the extracorporeal circulation circuit at different flow rates is calculated and analyzed. The Reynolds coefficient of the liquid in the circuit is calculated using formula (1-7);

[0168] R e =v m d / r (1-7)

[0169] Where: R e is the Reynolds coefficient; v m is the average flow velocity in the pipeline; d is the pipeline diameter; r is the liquid kinematic viscosity coefficient;

[0170] Liquid volume flow rate Q in the pipeline, average flow velocity vm And the pipe cross-sectional area S has the following relationship:

[0171]

[0172] Substituting formula (1-8) into formula (1-7) yields:

[0173] R e =v m d / r=4Q / (πdr) (1-9)

[0174] It is known that the blood pump flow rate of the extracorporeal membrane oxygenation system to be calibrated ranges from 500 to 8000 mL / min, the inner diameter of the adult extracorporeal circulation tubing is 3 / 8", and the human blood viscosity coefficient is 5.90×10 -6 m 2 / s, substituting the above conditions into formula (1-9) for calculation and analysis, when online calibrating the blood pump flow of the extracorporeal membrane oxygenation system, the measuring medium in the circulation pipeline is human blood. When the blood pump flow is in the range of 500-6130mL / min, the liquid flow state is laminar flow; in the range of 6130-8000mL / min, the liquid flow state is between laminar flow and turbulent flow;

[0175] That is, in the internal algorithm of the blood pump flow of the host 1 of the online calibration device, when the blood pump flow is in the range of 500 to 6130 mL / min, the flow rate correction coefficient k in formula (1-2) is 4 / 3; when the blood pump flow is in the range of 6130 to 8000 mL / min, the flow rate correction coefficient k in formula (1-2) is 1.119-0.0111 gR e ;

[0176] After the online calibration device host 1 calculates the blood pump flow calibration data according to the above internal algorithm, it is displayed on the touch screen of the online calibration device host 1 in the form of waveform and data according to the settings of the calibrator;

[0177] Step 4: The software automatically calculates the relative indication error of the blood pump flow and determines whether it exceeds the tolerance

[0178] After the calibrator manually inputs the blood pump flow monitoring value of the extracorporeal membrane oxygenation system to be calibrated through the touch screen of the online calibration device host 1, the online calibration device host 1 automatically calculates the relative indication error of the blood pump flow. When the absolute value of the relative indication error exceeds the preset error threshold, the blood pump flow calibration result is out of tolerance. At this time, the measurement software of the online calibration device host 1 pops up a prompt box to warn that the blood pump flow is out of tolerance, prompting the extracorporeal membrane oxygenation system user to check the working status of the extracorporeal membrane oxygenation system. The blood pump flow error threshold is usually set to 10%;

[0179] The relative indication error of the blood pump flow rate of the calibrated extracorporeal membrane oxygenation system can be calculated using formula (1-10):

[0180]

[0181] Where: Δ Q is the relative indication error of the extracorporeal membrane oxygenation system blood pump flow rate; Q' is the blood pump flow rate value corrected by the internal algorithm of the online calibration device host 1; Q0 is the blood pump flow rate monitoring value of the calibrated extracorporeal membrane oxygenation system input through the online calibration device host 1;

[0182] Step 5: Start the blood pump speed calibration function to collect data through Hall sensor 3

[0183] The calibrator starts the blood pump speed calibration program by clicking on the touch screen of the online calibration device host 1. The online calibration device host 1 transmits the start blood pump speed calibration instruction to the Hall sensor 3 through the second data line interface 306 of the data line 4. When the magnetic pole 504 on the rotating body 303 of the blood pump head 5 of the extracorporeal membrane oxygenation system being calibrated rotates past the Hall sensor 3 of the online calibration device, the free electrons moving in a direction in the direct current of the Hall element 302 of the Hall sensor 3 under the action of the magnetic field of the magnetic pole are deflected by the Lorentz force generated by the Hall effect, generating a voltage pulse signal. This voltage is called the Hall voltage, and the voltage value is calculated using formula (1-11):

[0184]

[0185] Among them: U H is the Hall voltage; R H is the Hall resistance value in the Hall element; I is the DC current value in the Hall element; B is the magnetic field strength value of the magnetic pole 504 in the blood pump head 5 of the calibrated extracorporeal membrane oxygenation system; h is the thickness of the Hall element;

[0186] The magnetic field strength of the internal magnetic pole 504 of the blood pump head 5 of different models of calibrated extracorporeal membrane oxygenation systems varies. Table 3 shows the magnetic field strength values ​​of the magnetic pole positions of the blood pump heads 5 of three mainstream models of extracorporeal membrane oxygenation systems. When the magnetic pole 504 in the blood pump heads 5 of different models of extracorporeal membrane oxygenation systems rotates past the Hall sensor 3 of the online calibration device, different Hall voltage values ​​are generated. The present invention achieves accurate measurement and calibration of the blood pump speed of different models of extracorporeal membrane oxygenation systems by setting different voltage thresholds in the internal algorithm of the blood pump speed of the main unit 1 of the online calibration device for different models of extracorporeal membrane oxygenation systems.

[0187] Table 3 Magnetic field strength at position 504 of the 5th magnetic pole of the blood pump head of three mainstream models of extracorporeal membrane oxygenation systems

[0188]

[0189] During the online calibration of the blood pump speed, when the Hall sensor 3 receives the calibration start instruction from the online calibration device host 1 through the data line 4, the timing unit 307 in the Hall sensor 3 starts timing, and the register 304 is cleared. When the voltage detection circuit 305 detects that the Hall element 302 generates a Hall voltage pulse signal and the voltage value U H When the voltage is greater than the voltage threshold U0 set in the algorithm for this model of extracorporeal membrane oxygenation system, the number of voltage pulses M in the register 304 is increased by 1; the Hall sensor 3 transmits the number of Hall voltage pulse signals M greater than the voltage threshold U0 recorded in the unit time register 304 to the online calibration device host 1 via the second data line interface 306 and the data line 4;

[0190] Step 6: The online calibration device host 1 calculates the blood pump speed data according to the internal algorithm

[0191] The online calibration device host 1 calculates the blood pump speed data of the calibrated extracorporeal membrane oxygenation system through the internal algorithm formula (1-12);

[0192]

[0193] Where: n is the calibration result of the blood pump speed; t m The timing unit 307 records the calibration time; M is the number of Hall voltage pulse signals exceeding the voltage threshold recorded in the register 304 during the calibration time;

[0194] After the online calibration device host 1 calculates the blood pump speed calibration data according to the above internal algorithm, it is displayed on the touch screen of the online calibration device host 1 in the form of waveforms and data according to the settings of the calibrator;

[0195] Step 7: The software automatically calculates the relative error of the blood pump speed indication and determines whether it exceeds the tolerance.

[0196] After the calibrator manually inputs the blood pump speed monitoring value of the extracorporeal membrane oxygenation system to be calibrated through the touch screen of the online calibration device host 1, the online calibration device host 1 automatically calculates the relative indication error of the blood pump speed. When the absolute value of the relative indication error exceeds the preset error threshold, the blood pump speed calibration result is out of tolerance. At this time, the measurement software of the online calibration device host 1 pops up a prompt box to warn that the blood pump speed is out of tolerance, prompting the extracorporeal membrane oxygenation system user to check the working status of the extracorporeal membrane oxygenation system. The blood pump speed error threshold is usually set to 5%;

[0197] The relative indication error of the blood pump speed of the calibrated extracorporeal membrane oxygenation system is calculated using formula (1-13):

[0198]

[0199] Where: Δ nis the relative indication error of the blood pump speed of the extracorporeal membrane oxygenation system; n is the blood pump speed value calculated by the internal algorithm of the online calibration device host 1; and n0 is the blood pump speed monitoring value of the calibrated extracorporeal membrane oxygenation system input through the online calibration device host 1.

[0200] Description of the blood pump flow data processing algorithm of the present invention:

[0201] (1) Algorithm improvement 1

[0202] The present invention realizes the function of online calibration of blood pump flow based on the time-difference ultrasonic flow measurement principle, and realizes non-invasive measurement of liquid volume flow in the pipeline by clamping the time-difference flow sensor 2 on the outside of the extracorporeal circulation pipeline of the extracorporeal membrane oxygenation system to be calibrated. The transducer arrangement in the time-difference flow sensor 2 is different and can be divided into Z-type, V-type, N-type, etc. Since the diameter of the circulation pipeline of the extracorporeal membrane oxygenation system is relatively small (the inner diameter of the adult pipeline is 3 / 8", and the wall thickness is 3 / 32"), the online calibration device adopts a Z-type time-difference flow sensor. This type of sensor transmits ultrasonic waves directly in the pipeline without refraction, which can reduce the sound loss during the propagation process. Its working principle is as follows Figure 8 As shown, the time-of-flight flow sensor 2 features an ultrasonic transmitter and receiver positioned relative to each other. During measurement, the transmitter emits an ultrasonic signal into the fluid being measured. Due to the influence of the fluid's flow velocity, the ultrasonic signal's propagation time downstream is shorter than its propagation time upstream along the same propagation path. By measuring this propagation time difference and leveraging its relationship with the measured fluid's flow velocity, the flow velocity of the measured medium in the pipeline can be calculated, thereby converting it into the flow rate.

[0203] This method analyzes the flow rate correction coefficient k in the blood pump flow algorithm based on the actual flow state of the liquid in the extracorporeal membrane oxygenation system's circulation tubing during online calibration. This factor, combined with the actual conditions of the extracorporeal membrane oxygenation system calibration, determines the flow rate correction coefficient for different flow rates and flow field distributions when treating patients with adult extracorporeal circulation tubing. This improves the accuracy of measurement data, reduces time difference measurement errors in blood pump flow data processing, and enhances the measurement accuracy of small flow points. The extracorporeal membrane oxygenation system to be calibrated has a blood pump flow range of 500 to 8000 mL / min, an adult extracorporeal circulation tubing inner diameter of 3 / 8", and a human blood viscosity coefficient of 5.90×10 -6 m 2 / s, substituting the above conditions into formula (1-9) for calculation and analysis, when online calibrating the blood pump flow of the extracorporeal membrane oxygenation system, the measuring medium in the circulation pipeline is human blood. When the blood pump flow is in the 500-6130mL / min range, the liquid flow state is laminar flow; in the 6130-8000mL / min range, the liquid flow state is between laminar flow and turbulent flow; that is, in the internal algorithm of the blood pump flow of the host 1 of the online calibration device, the blood pump flow is in the 500-6130mL / min range, and the flow rate correction coefficient k in formula (1-2) is 4 / 3; the blood pump flow is in the 6130-8000mL / min range, and the flow rate correction coefficient k in formula (1-2) is 1.119-0.0111gR e ;

[0204] (2) Algorithm improvement 2:

[0205] The blood pump flow calculation formula (1-5) includes the sound velocity c of ultrasonic signals propagating through human blood. This velocity fluctuates with blood temperature, affecting the accuracy of measurement data. The present invention adds temperature correction to the blood pump flow data processing algorithm. By incorporating Table 2, a correspondence between the sound velocity of human blood and temperature, the algorithm uses a time-of-day flow sensor temperature measurement element to collect real-time blood temperature in the calibrated extracorporeal membrane oxygenation system's circulation circuit. Interpolation is then used to calculate the accurate value of c at the current temperature, thereby minimizing the impact of temperature fluctuations on blood pump flow measurement and improving the accuracy of blood pump flow data measurement.

[0206] When the blood temperature collected by the temperature measuring element 204 is between two integer temperature points in Table 2, the corresponding sound velocity of the ultrasonic signal propagating in human blood can be calculated by interpolation method, as shown in the specific algorithm formula (1-3);

[0207] (3) Algorithm improvement three:

[0208] In the blood pump flow data processing of the present invention, the time difference data of multiple ultrasonic transmission and reception is combined and processed to extend the ultrasonic sound path, thereby reducing the time difference measurement error and improving the measurement accuracy of the blood pump flow at low flow points. If the time required for N downstream ultrasonic signals to be transmitted and received is T1, it includes the sum of the N inherent delay times τ0 and the sum of the single downstream propagation time t1 of the N ultrasonic signals in the measurement medium, human blood, that is, formula (1-14)

[0209] T1=N·τ0+N·t1 (1-14)

[0210] The time T2 required from the transmission to the reception of N countercurrent ultrasonic signals is expressed by formula (1-15):

[0211] T2=N·τ0+N·t2 (1-15)

[0212] At this time, the time difference formula of ultrasonic signal propagation upstream and downstream is (1-16)

[0213]

[0214] In the present invention, the number of repeated acquisitions, N, is set to different values ​​based on the actual blood pump flow range to be calibrated. The correspondence between the number of repeated acquisitions and the blood pump flow range during data processing is shown in Table 1. By employing this data processing algorithm, the acoustic range of the ultrasonic measurement signal during online blood pump flow calibration is extended, and the measured minute time quantities t1 and t2 can be converted into larger, more accurately measured time quantities T1 and T2, thereby improving the accuracy of blood pump flow measurement in the present invention.

[0215] The blood pump flow data of a certain type of extracorporeal membrane oxygenation system calibrated online using the present invention is shown in Table 4

[0216] Table 4: Blood pump flow rate data using online calibration of the present invention

[0217]

[0218]

[0219] According to Table 4, the blood pump flow online calibration function of the extracorporeal membrane oxygenation system online calibration device of the present invention can work normally and stably. The present invention can realize the online measurement and calibration of the blood pump flow of the extracorporeal membrane oxygenation system.

[0220] Description of the blood pump speed data processing algorithm of the present invention:

[0221] When the extracorporeal membrane oxygenation system is treating a patient, the blood pump head and the circulation pipeline are filled with the patient's blood. In order to solve the problem of online calibration of the blood pump speed while ensuring patient safety, a non-contact method should be used to measure the pump head speed. During online calibration, the blood pump head is filled with the patient's blood, and the rotating body and blades in the pump head are not visible. Therefore, commonly used optical non-contact speed measurement methods such as the stroboscopic method and the laser marking method are not suitable for online calibration of the blood pump speed. To solve the above problem, the present invention uses a Hall sensor to detect the voltage pulse signal generated by the periodically changing magnetic field based on the Hall effect during the rotation of the magnetic poles on the rotating body of the blood pump head to achieve online calibration of the blood pump speed.

[0222] During online calibration of the blood pump speed, when the magnetic pole 504 on the rotating body of the extracorporeal membrane oxygenation system blood pump head 5 rotates past the Hall sensor of the online calibration device, the free electrons moving in a direction in the DC current in the Hall element 302 of the Hall sensor 3 under the action of the magnetic field of the magnetic pole are deflected by the Lorentz force generated by the Hall effect, generating a voltage pulse signal. This voltage is called the Hall voltage, and its value can be calculated using formula (1-11).

[0223] The magnetic field strength of the internal magnetic poles of the blood pump head 5 varies across different models of extracorporeal membrane oxygenation (ECMO) systems. Table 3 shows the magnetic field strength values ​​for the magnetic pole positions of three mainstream models of ECMO blood pump heads 5. When the magnetic poles 504 of the blood pump heads 5 of different ECMO systems rotate past the Hall effect sensor 3 of the online calibration device, different Hall effect voltage values ​​are generated. The present invention accurately measures and calibrates the blood pump rotational speed of different ECMO systems by setting different voltage thresholds in the internal algorithm for each model.

[0224] When calibrating the blood pump speed online, when the online calibration device host 1 issues a calibration start instruction, the timing unit 307 in the Hall sensor 3 starts timing, and the register 304 is cleared. When the voltage detection circuit 305 detects that the Hall element 302 generates a Hall voltage pulse signal and the voltage value U H When the voltage is greater than the voltage threshold U0 set in the algorithm for this model of extracorporeal membrane oxygenation system, the number of voltage pulses M in register 304 is increased by 1, and the blood pump speed is calculated using formula (1-12).

[0225] The blood pump speed data of a certain type of extracorporeal membrane oxygenation system calibrated online using the present invention is shown in Table 5

[0226] Table 5 Online calibration of blood pump speed data using the present invention

[0227]

[0228]

[0229] According to Table 5, the blood pump speed online calibration function of the extracorporeal membrane oxygenation system online calibration device of the present invention can work normally and stably. The present invention can realize the online measurement and calibration of the blood pump speed of the extracorporeal membrane oxygenation system.

[0230] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as a preferred embodiment, it is not intended to limit the present invention. Any technician familiar with the present profession can make slight changes or modifications to equivalent embodiments using the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for calibrating an extracorporeal membrane oxygenation system, comprising the following steps: Step 1: Connect the online calibration device to the extracorporeal membrane oxygenation system circuit to be calibrated Before online calibration of the extracorporeal membrane oxygenation system, the time difference flow sensor (2) of the online calibration device is clamped on the extracorporeal circulation perfusion pipeline (6) of the extracorporeal membrane oxygenation system to be calibrated through the pipeline clamping slot (205). In order to ensure the stability of the liquid flow state in the pipeline, the pipeline where the time difference flow sensor (2) is installed should be straight without any height difference, and at least 10 cm straight pipe sections are reserved before and after the installation position of the time difference flow sensor (2); The Hall sensor (3) of the online calibration device is fixed on the measuring bracket, and the bracket is adjusted so that the measuring surface of the Hall sensor (3) touches the upper surface of the blood pump head (5) of the extracorporeal membrane oxygenation system, and the axis of the Hall sensor (3) is ensured to be perpendicular to the rotation plane of the rotating body (503); Step 2: Start the blood pump flow calibration function and collect data through the time difference method flow sensor (2). The calibration personnel starts the blood pump flow calibration program by clicking the touch screen of the online calibration device host (1). The online calibration device host (1) transmits the blood pump flow calibration start instruction to the time difference method flow sensor (2) through the first data line interface (206) of the data line (4). After the time difference method flow sensor (2) receives the instruction, the first ultrasonic transmitting and receiving unit (202) transmits an ultrasonic signal to the second ultrasonic transmitting and receiving unit (203) and starts timing. The ultrasonic signal is transmitted through the patient's blood flowing in the extracorporeal circulation perfusion tube and is received by the second ultrasonic transmitting and receiving unit (203). After the second ultrasonic transmitting and receiving unit (203) receives the ultrasonic signal, the timing is stopped to obtain the ultrasonic signal downstream propagation time. Then, the second ultrasonic transmitting and receiving unit (203) transmits an ultrasonic signal to the first ultrasonic transmitting and receiving unit (203). The unit (202) transmits an ultrasonic signal and starts timing. The ultrasonic signal is received by the first ultrasonic transmitting and receiving unit (202) after being transmitted through the patient's blood flowing in the extracorporeal circulation perfusion tube. The timing is stopped after the first ultrasonic transmitting and receiving unit (202) receives the ultrasonic signal, and the reverse flow propagation time of the ultrasonic signal is obtained. When designing a blood pump flow data acquisition program, the ultrasonic sound range is extended by combining the multiple transmission and reception time difference data of the ultrasonic signal, thereby reducing the time difference measurement error, and improving the measurement accuracy of the blood pump flow at a small flow point of the present invention. Specifically, different repeated acquisition times are set according to the measured blood pump flow range. The corresponding relationship between the repeated acquisition times and the blood pump flow is as follows. The time difference method flow sensor (2) respectively records N times of ultrasonic signal downstream propagation time and N times of ultrasonic signal reverse flow propagation time measurement data; the corresponding relationship between the repeated acquisition times and the blood pump flow range in data processing is as follows: At the same time, the temperature measuring element (204) in the time difference flow sensor (2) measures the blood temperature data in the extracorporeal circulation perfusion circuit (6) of the calibrated extracorporeal membrane oxygenation system; The time difference flow sensor (2) transmits the collected N ultrasonic signal downstream propagation time, N ultrasonic signal upstream propagation time measurement data and blood temperature data to the online calibration device host (1) via the first data line interface (206) and the data line (4); Step 3: The online calibration device host (1) calculates the blood pump flow data according to the internal algorithm The time difference flow sensor (2) is used to measure the difference in propagation time of the ultrasonic signal in the upstream and downstream directions, and the relationship between the measured difference in propagation time of the ultrasonic signal in the downstream and upstream directions and the flow velocity of the fluid to be measured is used to calculate the flow velocity of the measuring medium in the pipeline, and then the flow rate of the measuring medium is calculated in combination with the cross-sectional area of ​​the pipeline. When the blood pump flow rate is actually calibrated, the main unit (1) of the online calibration device calculates the flow data of the extracorporeal membrane oxygenation system blood pump to be calibrated by using the internal algorithm formula (1-1) and formula (1-2); The uncorrected blood pump flow is calculated using formula (1-1): in: Q is the uncorrected blood pump flow rate calculated by the main unit (1) of the online calibration device; c is the sound velocity of the ultrasonic signal propagating in human blood; d is the inner diameter of the extracorporeal circulation perfusion pipeline (6) of the extracorporeal membrane oxygenation system; T2 is the Nth reverse flow propagation time of the ultrasonic signal; T1 is the Nth downstream propagation time of the ultrasonic signal; N is the number of repeated transmission and reception of the ultrasonic signal obtained by looking up Table 1; α is the angle between the line connecting the first ultrasonic transmitting and receiving unit (202) and the second ultrasonic transmitting and receiving unit (203) in the sensor and the geometric center line of the pipeline; The temperature of the blood is collected by the temperature measuring element (204) in the time difference method flow sensor (2), and the propagation speed of the ultrasonic signal in the human blood in the algorithm formula (1-1) is corrected by temperature. The flow rate correction coefficient k is added to the formula (1-1) according to the blood flow state. After the correction by the above algorithm, the blood pump flow rate is calculated by (1-2) to obtain: Where: Q' is the corrected blood pump flow rate calculated by the main unit of the online calibration device (1); c t The blood temperature collected by the temperature measuring element (204) is obtained by looking up Table 2 corresponding to the sound velocity of the ultrasonic signal propagating in human blood at the temperature; k is a flow velocity correction coefficient; When the blood temperature collected by the temperature measuring element (204) is between two integer temperature points in Table 2, the corresponding sound velocity of the ultrasonic signal propagating in human blood is calculated by interpolation method, and the specific algorithm formula is (1-3); Where: w t The temperature measuring element (204) collects the blood temperature; t To collect blood temperature w according to the temperature measuring element (204) t The speed of sound propagation of ultrasonic signals in human blood is calculated by data interpolation method according to the following relationship between the speed of sound propagation of ultrasonic signals in human blood and temperature; w1 is the ratio of the speed of sound propagation of ultrasonic signals in human blood and temperature to w. t The lower adjacent integer temperature point; w2 is the following ratio of the ultrasonic signal propagation speed in human blood to the corresponding relationship between the temperature and the value of w t The corresponding relationship between the sound velocity of the ultrasonic signal in human blood and the temperature is as follows: c1 is the sound velocity of the human blood corresponding to the temperature w1 in the following corresponding relationship between the sound velocity of the ultrasonic signal in human blood and the temperature; c2 is the sound velocity of the human blood corresponding to the temperature w2 in the following corresponding relationship between the sound velocity of the ultrasonic signal in human blood and the temperature; the corresponding relationship between the sound velocity of the ultrasonic signal in human blood and the temperature is as follows: In order to improve the accuracy of flow measurement data, the flow rate correction coefficient k in the flow data algorithm was analyzed. Combined with the actual situation of calibrating the extracorporeal membrane oxygenation system, the flow rate correction coefficients for different flow rates and different flow field distributions when using adult extracorporeal circulation circuits to treat patients were determined. The following compensation coefficients were obtained to reflect this correction, respectively according to the Reynolds coefficient R e <2300、Reynolds coefficient R e >4000 and Reynolds number 2300<R e <4000, adjust the flow rate correction coefficient k in three cases; Therefore, in formula (1-2), the velocity correction coefficient k is defined as the linear average velocity v and the surface average velocity v m The velocity correction coefficient is related to the flow state of the measured fluid. The velocity correction coefficient k depends on the Reynolds number Re of the fluid in the pipeline. Specifically: When the fluid is laminar (Reynolds coefficient R e <2300): When the fluid becomes turbulent (Reynolds coefficient R e >4000): When the fluid flow state is between laminar flow and turbulent flow (i.e. Reynolds coefficient 2300<R e <4000): k=1.119-0.0111gR e (1-6) When calibrating the extracorporeal membrane oxygenation system online, the measurement medium is human blood, and the Reynolds coefficient of the extracorporeal circulation circuit at different flow rates is calculated and analyzed. The Reynolds coefficient of the liquid in the circuit is calculated using formula (1-7); R e =v m d / r (1-7) Where: R e is the Reynolds coefficient; v m is the average flow velocity in the pipeline; d is the pipeline diameter; r is the liquid kinematic viscosity coefficient; Liquid volume flow rate Q in the pipeline, average flow velocity v m And the pipe cross-sectional area S has the following relationship: Substituting formula (1-8) into formula (1-7) yields: R e =v m d / r=4Q / (πdr) (1-9) It is known that the blood pump flow rate of the extracorporeal membrane oxygenation system to be calibrated ranges from 500 to 8000 mL / min, the inner diameter of the adult extracorporeal circulation tubing is 3 / 8", and the human blood viscosity coefficient is 5.90×10 -6 m 2 / s, substitute the above conditions into formula (1-9) for calculation and analysis. When calibrating the blood pump flow of the actual online extracorporeal membrane oxygenation system, the measuring medium in the circulation pipeline is human blood. When the blood pump flow is in the range of 500-6130mL / min, the liquid flow state is laminar flow; in the range of 6130-8000mL / min, the liquid flow state is between laminar flow and turbulent flow. That is, in the internal algorithm of the blood pump flow of the main unit (1) of the online calibration device, when the blood pump flow is in the range of 500 to 6130 mL / min, the flow rate correction coefficient k in formula (1-2) is 4 / 3; when the blood pump flow is in the range of 6130 to 8000 mL / min, the flow rate correction coefficient k in formula (1-2) is 1.119-0.0111 gR e ; After the online calibration device host (1) calculates the blood pump flow calibration data according to the above internal algorithm, the data is displayed on the touch screen of the online calibration device host (1) in the form of waveforms and data according to the settings of the calibration personnel; Step 4: The software automatically calculates the relative indication error of the blood pump flow and determines whether it exceeds the tolerance After the calibration personnel manually input the blood pump flow monitoring value of the extracorporeal membrane oxygenation system to be calibrated through the touch screen of the online calibration device host (1), the online calibration device host (1) automatically calculates the relative indication error of the blood pump flow. When the absolute value of the relative indication error exceeds a preset error threshold, the blood pump flow calibration result is out of tolerance. At this time, the measurement software of the online calibration device host (1) pops up a prompt box to warn that the blood pump flow is out of tolerance, prompting the user of the extracorporeal membrane oxygenation system to pay attention to check the working status of the extracorporeal membrane oxygenation system. The relative error threshold of the blood pump flow is usually set to 10%; The relative indication error of the calibrated extracorporeal membrane oxygenation system blood pump flow rate is calculated using formula (1-10): Where: Δ Q is the relative indication error of the extracorporeal membrane oxygenation system blood pump flow rate; Q' is the blood pump flow rate value corrected by the internal algorithm of the online calibration device host (1); Q0 is the calibrated extracorporeal membrane oxygenation system blood pump flow rate monitoring value input through the online calibration device host (1); Step 5: Start the blood pump speed calibration function to collect data through the Hall sensor (3) The calibration personnel starts the blood pump speed calibration program by clicking on the touch screen of the online calibration device host (1). The online calibration device host (1) transmits the blood pump speed calibration start instruction to the Hall sensor (3) through the second data line interface (306) of the data line (4). When the magnetic pole (504) on the rotating body (503) in the blood pump head (5) of the calibrated extracorporeal membrane oxygenation system rotates past the Hall sensor (3) of the online calibration device, the free electrons in the direct current of the Hall element (302) in the Hall sensor (3) that move in a direction under the action of the magnetic field of the magnetic pole (504) are deflected by the Lorentz force generated by the Hall effect, generating a voltage pulse signal. The voltage is called the Hall voltage, and the voltage value is calculated by formula (1-11): Among them: U H is the Hall voltage; R H is the Hall resistance value in the Hall element (302); I is the DC current value in the Hall element (302); B is the magnetic field intensity value of the magnetic pole (504) in the blood pump head (5) of the calibrated extracorporeal membrane oxygenation system; h is the thickness of the Hall element (302); Different models of calibrated extracorporeal membrane oxygenation system blood pump heads (5) have different magnetic field strengths of the internal magnetic poles (504), as shown in the following three mainstream models of extracorporeal membrane oxygenation system blood pump heads (5) magnetic poles (504) The position magnetic field strength shows the magnetic field strength values ​​of the magnetic pole positions of the blood pump heads (5) of three mainstream models of extracorporeal membrane oxygenation systems. When the magnetic poles (504) in the blood pump heads (5) of different models of extracorporeal membrane oxygenation systems rotate through the Hall sensor (3) of the online calibration device, different Hall voltage values ​​are generated. Different voltage thresholds are set for different models of extracorporeal membrane oxygenation systems in the internal algorithm of the blood pump speed of the online calibration device host (1), so that accurate measurement and calibration of the blood pump speeds of different models of extracorporeal membrane oxygenation systems can be achieved. The magnetic field strengths at the positions of the magnetic poles (504) of the blood pump heads (5) of three mainstream models of extracorporeal membrane oxygenation systems are shown below: During online calibration of the blood pump speed, when the Hall sensor (3) receives a calibration start instruction from the online calibration device host (1) via the data line (4), the timing unit (307) in the Hall sensor (3) starts timing, and the register (304) is cleared. When the voltage detection circuit (305) detects that the Hall element (302) generates a Hall voltage pulse signal and the voltage value U H When the voltage is greater than the voltage threshold U0 set in the algorithm for the extracorporeal membrane oxygenation system of this model, the number of voltage pulses M in the register (304) is increased by 1; the Hall sensor (3) transmits the number of Hall voltage pulse signals M greater than the voltage threshold U0 recorded in the unit time register (304) to the online calibration device host (1) via the second data line interface (306) and the data line (4); Step 6: The online calibration device host (1) calculates the blood pump speed data according to the internal algorithm The main unit (1) of the online calibration device calculates the blood pump speed data of the calibrated extracorporeal membrane oxygenation system through the internal algorithm formula (1-12); Where: n is the calibration result of the blood pump speed; t m The timing unit (307) records the calibration duration; M is the number of Hall voltage pulse signals exceeding the voltage threshold recorded in the register (304) within the calibration duration; After the online calibration device host (1) calculates the blood pump speed calibration data according to the above internal algorithm, the waveform and data are displayed on the touch screen of the online calibration device host (1) according to the settings of the calibration personnel; Step 7: The software automatically calculates the relative error of the blood pump speed indication and determines whether it exceeds the tolerance. After the calibration personnel manually input the blood pump speed monitoring value of the extracorporeal membrane oxygenation system to be calibrated through the touch screen of the online calibration device host (1), the online calibration device host (1) automatically calculates the relative indication error of the blood pump speed. When the absolute value of the relative indication error exceeds a preset error threshold, the blood pump speed calibration result is out of tolerance. At this time, the measurement software of the online calibration device host (1) pops up a prompt box to warn that the blood pump speed is out of tolerance, prompting the extracorporeal membrane oxygenation system user to pay attention to check the working status of the extracorporeal membrane oxygenation system. The blood pump speed error threshold is usually set to 5%; The relative indication error of the blood pump speed of the calibrated extracorporeal membrane oxygenation system is calculated using formula (1-13): Where: Δ n is the relative indication error of the blood pump speed of the extracorporeal membrane oxygenation system; n is the blood pump speed value calculated by the internal algorithm of the online calibration device host (1); and n0 is the blood pump speed monitoring value of the calibrated extracorporeal membrane oxygenation system input through the online calibration device host (1).

2. The online calibration method for an extracorporeal membrane oxygenation system according to claim 1, characterized in that: In the blood pump flow data processing, the multiple transmission and reception time difference data of ultrasound are combined and processed to extend the ultrasonic sound path, reduce the time difference measurement error, and improve the blood pump flow measurement accuracy; If the time required for N downstream ultrasonic signals to be transmitted and received is T1, it includes the sum of N inherent delay times τ0 and the sum of the single downstream propagation time t1 of N ultrasonic signals in the measurement medium human blood, that is, formula (1-14) T1=N·τ0+N·t1 (1-14) The time T2 required from the transmission to the reception of N countercurrent ultrasonic signals is expressed by formula (1-15): T2=N·τ0+N·t2 (1-15) At this time, the time difference formula of ultrasonic signal propagation upstream and downstream is (1-16) The number of repeated acquisitions N is set to different values ​​according to the actual calibration blood pump flow range. The corresponding relationship between the number of repeated acquisitions and the blood pump flow range in data processing is shown in Table 1. By adopting this data processing algorithm, the measurement sound range of the ultrasonic measurement signal during the online calibration of the blood pump flow is extended, and the measured small time quantities t1 and t2 can be converted into larger time quantities T1 and T that are easier to measure accurately. 2， This improves the accuracy of blood pump flow measurement.

3. An online calibration device using the online calibration method for an extracorporeal membrane oxygenation system according to any one of claims 1 to 2, characterized in that: The invention mainly comprises: an online calibration device host (1), a time difference flow sensor (2), a Hall sensor (3) and a data line (4), wherein the Hall sensor (3) is connected to the online calibration device host (1) via the data line (4), one end of the time difference flow sensor (2) is connected to the online calibration device host (1) via the data line (4), the other end of the time difference flow sensor (2) is connected to an extracorporeal membrane oxygenation system extracorporeal circulation perfusion pipeline (6), one end of a blood pump head (5) of the extracorporeal membrane oxygenation system is connected to a patient (8) via the extracorporeal membrane oxygenation system extracorporeal circulation perfusion pipeline (6), and the other end of the blood pump head (5) of the extracorporeal membrane oxygenation system is connected to a patient (8) via the extracorporeal membrane oxygenation system extracorporeal circulation drainage pipeline (7).

4. The online calibration device for an extracorporeal membrane oxygenation system according to claim 3, characterized in that: The time difference flow sensor (2) comprises a flow sensor housing (201) and a first ultrasonic transmitting and receiving unit (202), a second ultrasonic transmitting and receiving unit (203), a temperature measuring element (204), a pipeline slot (205), and a first data line interface (206) arranged in the flow sensor housing (201). The first ultrasonic transmitting and receiving unit (202) and the second ultrasonic transmitting and receiving unit (203) are arranged at two ends of the pipeline slot (205) relative to each other. The angle between the geometric center line of the first ultrasonic transmitting and receiving unit (202) and the second ultrasonic transmitting and receiving unit (203) and the center line of the pipeline slot (205) is α, and the range of α is 40° to 50°. The temperature measuring element (204) is located on the side wall of the pipeline slot (205). The time difference flow sensor (2) is connected to the data line (4) in sequence through the first data line interface (206).

5. The online calibration device for an extracorporeal membrane oxygenation system according to claim 3, characterized in that: The Hall sensor (3) comprises a sensor housing (301), a Hall element (302), a DC power supply circuit (303), a register (304), a voltage detection circuit (305), and a second data line interface (306) arranged in the sensor housing (301), wherein the voltage detection circuit (305) is connected to the Hall element (302) and is used to detect the voltage value of the Hall voltage generated by the Hall element (302) under the action of an external magnetic field, the register (304), a timing unit (307) are connected to the voltage detection circuit (305), and the Hall sensor (3) is sequentially connected to the online calibration device host (1) via the second data line interface (306) and the data line (4).

6. The online calibration device for an extracorporeal membrane oxygenation system according to claim 3, characterized in that: The blood pump head (5) of the extracorporeal membrane oxygenation system comprises: a housing (501) and a rotating shaft (502), a rotating body (503) and a magnetic pole (504) arranged in the housing (501), wherein a plurality of magnetic poles (504) are evenly distributed on the edge of the rotating body (503), the rotating shaft (502) is arranged on the central axis inside the housing (501), and the rotating body (503) is installed at the bottom of the housing (501) with the rotating shaft (502) as the axis. When a patient is clinically treated, the rotating body (503) in the blood pump head (5) of the extracorporeal membrane oxygenation system rotates. When the body (503) rotates at high speed with the rotation axis (502) as the axis, the magnetic pole (504) rotates at high speed along with the rotating body (503), and the Hall sensor (3) is arranged at a position perpendicular to the rotation plane of the rotating body (503) and close to the edge of the upper surface of the shell (501). When the magnetic pole (504) on the rotating body (503) in the calibrated extracorporeal membrane oxygenation system blood pump head (5) approaches the detection surface of the Hall element (302) during the rotation process, the Hall element (302) generates a Hall voltage signal under the action of the magnetic field of the magnetic pole (504).

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