Flow and pressure monitoring and control system for perfusion process before donor lung acquisition

Abstract

The invention relates to the technical field of organ transplantation medical instruments, and particularly discloses a flow and pressure monitoring and control system for a perfusion process before donor lung acquisition. The system comprises an integrated disposable perfusion pipeline assembly, a multi-point pressure monitoring module, a flow adjusting module, a real-time feedback control module, a data storage and analysis module and a man-machine interaction module. A multi-point pressure interface and an electric control proportional valve are arranged in the integrated disposable perfusion pipeline assembly, and are matched with a reusable driving part, so that sterile safety and operation simplification are realized; the multi-point pressure monitoring module collects pressure data of positions such as a pulmonary artery inlet, a far end and a left atrium, and the flow adjusting module accurately adjusts the perfusion flow velocity based on an electric control proportional valve. The problems of insufficient perfusion precision, non-uniform distribution, lack of dynamic feedback, incomplete consumable design and the like in the prior art are solved, the donor lung perfusion safety and effectiveness are remarkably improved, and a guarantee is provided for successful lung transplantation.

Description

Technical Field

[0001] This invention relates to the field of medical device technology, specifically to a flow and pressure monitoring and control system for the perfusion process before donor lung acquisition. Background Technology

[0002] Lung transplantation is the only effective surgical treatment for end-stage lung diseases (such as idiopathic pulmonary fibrosis, chronic obstructive pulmonary disease, cystic fibrosis, and pulmonary hypertension), and its success largely depends on the quality of the donor lung. Lung tissue is extremely sensitive to ischemia-reperfusion injury; therefore, in situ perfusion is a crucial step in the donor lung retrieval process to ensure lung function and reduce ischemia-reperfusion injury.

[0003] Donor lung retrieval commonly employs in situ cold perfusion: cryopreservation fluid is infused into the pleural cavity via the main pulmonary artery (PA) in an antegrade manner, with adequate drainage through the left atrium / left atrial appendage to rapidly cool the lung, remove residual blood and microemboli, and mitigate ischemia-reperfusion injury. Some medical centers combine antegrade perfusion with retrograde (pulmonary vein → PA) flushing to further improve flushing uniformity. Regardless of whether the donor is a brain-dead donor (DBD) or a circulatory-dead donor (DCD), the perfusion process must meet the technical requirements of low pressure, uniformity, rapid flow, and low temperature, while also requiring gentle ventilation and local pleural cooling measures.

[0004] However, current clinical methods of in vivo fluid infusion still have many shortcomings. They primarily rely on simple, disposable infusion tubing and gravity-suspended infusion bags. Some departments, in pursuit of faster flow rates, resort to temporary methods such as manually squeezing the infusion bag or using cuff-type pressurization. While these methods offer advantages in accessibility and low cost, they have significant deficiencies in quantitative monitoring, process control, and outcome evaluation, as detailed below: Main problems with existing technology The lack of real-time, quantitative flow / pressure information in existing in vivo perfusion tubing often prevents surgeons from assessing the adequacy of perfusion. They typically lack integrated flow meters and pressure taps, relying instead on indirect methods such as the rate of fluid level drop, visual observation of the drip chamber, clarity of left atrial reflux, and changes in lung surface color. Over-pressure perfusion can cause pulmonary capillary endothelial damage and pulmonary edema, while under-pressure / under-flow can lead to insufficient flushing and cooling, both of which can negatively impact early post-transplant lung function and complication risks, potentially even leading to donor lung disposal in severe cases.

[0005] Primitive pressurization methods, lacking feedback loops, are commonly used in clinical practice to overcome drainage limitations or to increase flow rate in a short period. These methods include manual squeezing and pressurizing the bag with a cuff / shell. However, there are no standardized upper limit controls or alarm thresholds, and there is no quantitative correlation between pressurization and the patient-side perfusion pressure (proximal PA). This leads to pressurization practices relying entirely on individual experience, making it difficult to avoid the risk of "over-pressurization for the sake of speed," and also hindering the establishment of reproducible process windows across multiple centers, thus impeding the standardization and normalization of perfusion procedures.

[0006] The inability to correlate "process parameters" with "perfusion outcomes / postoperative results" is a significant challenge. Current in vivo perfusion procedures are mostly one-off, unrecorded open processes, lacking simultaneous collection and retention of key variables such as instantaneous flow rate (Q), upstream tubing pressure (P1), patient-side proximal PA pressure (P2), total perfusion volume, and perfusion timeline. Therefore, it is difficult to conduct systematic correlation analyses of "perfusion process parameters → perfusion effectiveness (e.g., left atrial reflux clearing time, lung parenchymal appearance, retrograde reflux blood staining degree) → postoperative primary graft dysfunction (PGD) / oxygenation indicators" at the individual case or multicenter level, which also hinders quality traceability and standardized training.

[0007] The limitations of in vivo perfusion procedures, particularly in the thoracic surgical field (4-8°C), present significant challenges. These limitations necessitate specific requirements for equipment materials, including low-temperature flexibility, resistance to atomization, rapid degassing / defoaming capabilities, and coordination with the cardiac team (left atrial decompression). While existing ex vivo (extracorporeal) perfusion systems have evolved with sophisticated pump control, sensing, and data management platforms, their bulky size, complex sterilization pathways, intricate fluid routing, high cost, and poor cross-departmental usability make them unsuitable for direct application in the in vivo stage. Consequently, the in vivo perfusion process has long relied on outdated methods based on "simple tubing and experience-based judgment."

[0008] The lack of safety boundaries and the prominent risk of misuse are due to uncertainties such as tubing resistance, clamping status, and gas content in the defoaming chamber between the pressure at the pressurized end (bag side) and the actual perfusion pressure at the patient end (proximal PA). Monitoring only the bag side pressure or the suspension height of the perfusion bag is insufficient to represent the actual pressure entering the pulmonary circulation. In addition, the variety of disposable tubing specifications and the lack of uniformity in end connectors create potential risks of misconnection and overpressure, posing serious hidden dangers to the safety of the donor lung.

[0009] The design of disposable consumables is imperfect. Existing infusion tubing and sensors are often installed separately and require multiple connections, which not only increases the complexity of operation and the workload of medical staff, but also significantly increases the risk of infection. At the same time, some sensors cannot be used once, and the cleaning and disinfection process is cumbersome, which affects work efficiency and makes it difficult to guarantee sterility, further limiting the safety and convenience of infusion operation.

[0010] In summary, existing technologies for in-situ perfusion before donor lung retrieval generally suffer from insufficient perfusion accuracy and safety, uneven local perfusion, lack of dynamic monitoring and real-time feedback adjustment, and imperfect design of disposable consumables, which seriously affect the quality of donor lungs and the success rate of lung transplantation. Therefore, developing a pre-donor lung retrieval perfusion system that can accurately monitor and control perfusion flow and pressure, ensure perfusion uniformity, simplify the operation process, and reduce the risk of infection has significant clinical value and practical implications. Summary of the Invention

[0011] The purpose of this invention is to overcome the above-mentioned defects of the prior art and provide a flow and pressure monitoring and control system for the perfusion process before donor lung acquisition. This system can achieve accurate monitoring and dynamic adjustment of flow and pressure during the perfusion process, ensure uniform perfusion of all parts of the lung, simplify the operation process, reduce the risk of cross-contamination, and at the same time realize the complete recording and analysis of perfusion process parameters, providing data support for donor lung quality assessment and perfusion process optimization, and ultimately improving the success rate of lung transplantation surgery.

[0012] To achieve the above objectives, the present invention provides the following technical solution: a flow and pressure monitoring and control system for the perfusion process before donor lung acquisition, comprising an integrated disposable perfusion tubing assembly, a multi-point pressure monitoring module, a flow regulation module, a real-time feedback control module, a data storage and analysis module, and a human-computer interaction module; the integrated disposable perfusion tubing assembly includes a perfusion fluid input end, a built-in pressure tap, a flow sensing channel, an electronically controlled proportional valve mounting cavity, a lung connection end, and a drainage channel; the built-in pressure tap is provided with at least three, corresponding to the pulmonary artery inlet, the distal end of the pulmonary artery, and the left atrial position, respectively; the electronically controlled proportional valve mounting cavity is used to fix the disposable electronically controlled proportional valve actuator; the multi-point pressure monitoring module connects to the built-in pressure tap via a pressure sensor. The pressure tap is sealed and connected for real-time acquisition of pressure data from different locations and transmission to the real-time feedback control module. The flow regulation module includes an electronically controlled proportional valve, a drive unit, and a flow velocity detection element. The flow velocity detection element is located within the flow sensing channel and is used to detect the perfusion fluid flow rate in real time. The real-time feedback control module is electrically connected to the multi-point pressure monitoring module, the flow regulation module, the data storage and analysis module, and the human-machine interface module. Based on pressure data, flow velocity data, and preset lung function index thresholds, it automatically generates flow and pressure regulation commands and sends them to the flow regulation module. The data storage and analysis module is used to synchronously store key parameters such as pressure, flow rate, perfusion time, and total perfusion volume. The human-machine interface module is used for parameter setting, data display, and alarm prompts.

[0013] Furthermore, the integrated disposable infusion tubing assembly is integrally injection molded using medical-grade polyvinyl chloride or thermoplastic elastomer material, with an ultra-slippery antibacterial coating on the inner wall of the tubing. The infusion fluid input end is equipped with a Luer locking connector and a built-in one-way valve to prevent infusion fluid backflow.

[0014] Furthermore, the pressure sensor of the multi-point pressure monitoring module adopts a miniature strain gauge pressure sensor with a measurement range of 0-100cmH2O, an accuracy of ±0.5cmH2O, and a response time of ≤10ms. The pressure sensor and the built-in pressure tap are detachably connected through a sterile sealing plug, and a leak-proof gasket is provided at the connection.

[0015] Furthermore, the electronically controlled proportional valve of the flow regulation module is a direct-acting electromagnetic proportional valve with a flow regulation range of 10-200 mL / min and an adjustment accuracy of ±2 mL / min. The drive unit is a stepper motor drive module that controls the valve opening of the electronically controlled proportional valve through pulse signals. The flow velocity detection element is an ultrasonic Doppler flow velocity sensor with a measurement error ≤3%.

[0016] Furthermore, the real-time feedback control module includes a microcontroller, a signal conditioning circuit, a threshold comparison unit, and an adjustment command generation unit. The signal conditioning circuit is used to filter, amplify, and perform analog-to-digital conversion on the analog signals output by the pressure sensor and the flow velocity detection element. The threshold comparison unit compares the processed pressure data and flow velocity data with preset safety thresholds. The adjustment command generation unit generates an electronically controlled proportional valve opening adjustment command based on the comparison results and the calculation results of transpulmonary pressure difference and pulmonary vascular resistance.

[0017] Furthermore, the transpulmonary pressure gradient is calculated by the difference between the pulmonary artery inlet pressure and the left atrial pressure, and the pulmonary vascular resistance is calculated by the ratio of the transpulmonary pressure gradient to the perfusion flow rate. The preset safety thresholds include the maximum perfusion pressure threshold, the minimum perfusion pressure threshold, the maximum flow rate threshold, and the minimum flow rate threshold, and the thresholds can be modified through the human-computer interaction module.

[0018] Furthermore, the data storage and analysis module includes a storage unit and a data analysis unit. The storage unit uses an SD card or a solid-state drive and stores data including real-time pressure data, real-time flow data, adjustment command data, infusion start time, infusion end time, and total infusion volume. The storage format supports CSV and Excel. The data analysis unit can perform statistical analysis on the stored data and generate infusion process curves and key parameter reports.

[0019] Furthermore, the human-machine interaction module includes a touch screen, physical buttons, and an audible and visual alarm device. The touch screen is used to display real-time monitoring data, preset parameters, and system status. The physical buttons are used for emergency shutdown, parameter confirmation, and mode switching. The audible and visual alarm device triggers an alarm when the pressure or flow exceeds a preset threshold, or when there is a sensor malfunction or pipeline blockage.

[0020] Furthermore, it also includes a temperature monitoring module, which comprises a temperature sensor and a temperature signal processing unit. The temperature sensor is located at the infusion fluid input end and the lung connection end of the integrated disposable infusion tubing assembly, and is used to detect the infusion fluid temperature and lung surface temperature in real time. The detection range is 0-40℃, and the accuracy is ±0.2℃. The temperature signal processing unit transmits the temperature data to the real-time feedback control module. When the temperature exceeds the preset range, the real-time feedback control module controls the human-machine interaction module to sound an alarm.

[0021] Furthermore, the integrated disposable infusion tubing assembly also includes a storage chamber and a defoaming device. The storage chamber is located between the infusion fluid input end and the flow sensing channel, and has a volume of 50-100 mL. The defoaming device adopts a centrifugal defoaming structure and is located between the storage chamber and the mounting chamber of the electronically controlled proportional valve to remove air bubbles from the infusion fluid.

[0022] Compared with the prior art, the present invention has the following significant advantages: (1) Significantly improved perfusion accuracy and safety. This invention uses a multi-point pressure monitoring module to collect pressure data at the pulmonary artery inlet, distal end, and left atrium. Combined with the precise flow rate detection of the flow regulation module, it can monitor the pressure and flow status of the pulmonary circulation in real time. The real-time feedback control module is based on the PID control algorithm and automatically adjusts the opening of the electronically controlled proportional valve according to the pressure and flow data to ensure that the perfusion pressure and flow are always within the preset safety range. This avoids problems such as overpressure and underflow caused by manual operation or simple control in the prior art, effectively prevents perfusion-related injuries such as pulmonary capillary endothelial damage and pulmonary edema, and significantly improves the safety of donor lung perfusion.

[0023] (2) Achieving uniform lung perfusion: By calculating the transpulmonary pressure difference and pulmonary vascular resistance using multi-point pressure data, the compliance of pulmonary vessels and the uniformity of perfusion can be accurately assessed. When local perfusion non-uniformity is detected (such as an abnormally large transpulmonary pressure difference), the real-time feedback control module automatically adjusts the flow distribution to ensure that all parts of the lung receive sufficient perfusion fluid. This solves the problem of insufficient local perfusion that is easily caused by existing antegrade perfusion methods, improves the flushing effect of perfusion fluid and the uniformity of lung cooling, and helps to reduce ischemia-reperfusion injury.

[0024] (3) Possesses dynamic monitoring and real-time feedback adjustment functions. The system of the present invention can collect multiple key parameters such as pressure, flow rate, and temperature in real time, and realize closed-loop control through the real-time feedback control module. It can automatically adjust the infusion parameters without manual intervention, reducing the errors and risks caused by manual operation. At the same time, the system has a complete alarm function, which can promptly detect and prompt abnormalities such as overpressure, underflow, sensor failure, and pipeline blockage, facilitating rapid handling by medical staff and further ensuring the safety and stability of the infusion process.

[0025] (4) Integrated disposable consumable design simplifies operation and reduces infection risk. The integrated disposable infusion tubing assembly integrates key components such as pressure taps, flow sensing channels, electronically controlled proportional valve mounting chambers, and defoaming devices, eliminating the need for multiple connections, simplifying assembly and operation processes, and reducing the workload of medical staff. This assembly is for single use only and is discarded after use, avoiding the risk of cross-contamination from reuse; at the same time, the assembly has a built-in sterile filter membrane and sealing structure, further improving sterility and safety. Reusable drive components and control modules can be reused after a strict disinfection process, reducing medical costs.

[0026] (5) Complete Recording and Analysis of Perfusion Process Parameters: The data storage and analysis module can synchronously store all key parameters during the perfusion process, including pressure, flow rate, temperature, perfusion time, and total perfusion volume. The data is accurately timestamped, providing a reliable basis for quality traceability. The data analysis unit can generate detailed graphs and statistical reports, and supports correlation analysis between perfusion process parameters and perfusion effectiveness and postoperative outcomes. This helps medical staff summarize experience, optimize perfusion techniques, promote the standardization and normalization of donor lung perfusion operations, and provide data support for multi-center clinical research.

[0027] (6) The integrated disposable perfusion tubing assembly, adapted to in vivo perfusion engineering and human factors constraints, is small in size and compact in structure, making it suitable for use in the confined space of the thoracic surgical field. The materials used in the assembly have good low-temperature flexibility and can maintain good flexibility even at low temperatures of 4-8℃ without affecting the flow of the perfusion fluid. The defoaming device can effectively remove air bubbles from the perfusion fluid and avoid gas embolism. The touch screen of the human-machine interface module is easy to operate, the physical buttons are reasonably laid out, and the emergency stop button is easy to access quickly, meeting the human factors engineering requirements of the operating room.

[0028] (7) Clear safety boundaries reduce the risk of misuse. The system ensures the accuracy of pressure monitoring and clarifies the safety boundaries by directly monitoring the actual pressure at the patient end (proximal PA, left atrium) rather than relying on bag-side pressure or suspension height. At the same time, the interfaces of the integrated disposable infusion tubing assembly adopt a standardized design to avoid the risk of misconnection; parameter settings require password confirmation to prevent problems such as overpressure and overflow caused by misoperation, further reducing the risk of misuse. Attached Figure Description

[0029] Figure 1 is a schematic diagram of the overall structure of the present invention. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein in the specification of the application is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims and drawings of this application are intended to cover non-exclusive inclusion.

[0032] The term "embodiment" as used herein means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of the phrase "embodiment" in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0033] Furthermore, the terms "first," "second," etc., in the specification and claims of this application or in the aforementioned drawings are used to distinguish different objects rather than to describe a specific order, and may explicitly or implicitly include one or more of the features.

[0034] To enable those skilled in the art to better understand the present application, the following will be combined with... Figure 1 The technical solutions in the embodiments of this application will be clearly and completely described.

[0035] System component selection and parameter determination Integrated disposable injection tubing assembly Material Selection: Medical-grade TPE material is used, which has excellent low-temperature flexibility (no brittleness at 4℃), biocompatibility, and processing performance, and meets the ISO 10993 biocompatibility standard. The inner wall of the tubing is coated with a medical-grade super-lubricating coating (such as PTFE coating), with a coating thickness of 5-10μm and a surface roughness Ra≤0.1μm, reducing the flow resistance of the perfusion fluid and bacterial adhesion.

[0036] Structural parameters: The Luer locking connector at the infusion fluid inlet conforms to ISO 80369 standard, ensuring universality. The reservoir volume is 80mL, effectively buffering the infusion fluid and stabilizing pressure. The degassing device has a degassing chamber diameter of 20mm and a height of 30mm. The impeller speed is related to the infusion fluid flow rate; when the flow rate is 50mL / min, the impeller speed is approximately 300r / min, and the bubble separation efficiency is ≥95%.

[0037] There are three built-in pressure taps, located 10cm (pulmonary artery inlet), 5cm (distal pulmonary artery), and at the drainage channel inlet (left atrium) from the lung connection end. The inner diameter of the tap is 2mm. The sealing plug is made of medical-grade silicone rubber with a Shore A hardness of 50-60 degrees to ensure sealing performance.

[0038] The flow sensing channel has an inner diameter of 6mm and a length of 4cm to ensure accurate flow velocity detection by the ultrasonic Doppler flow sensor. The mounting cavity of the electronically controlled proportional valve has an inner diameter of 15mm, a depth of 20mm, and a positioning slot width of 2mm to ensure secure installation of the electronically controlled proportional valve.

[0039] The lung connection port has an interface diameter of 18Fr, compatible with commonly used pulmonary artery cannulas. The elastic sealing structure allows for 3mm of expansion and contraction, ensuring a sealed connection for cannulas of different sizes. The drainage channel has an inner diameter of 8mm, and the flow rate adjustment clamp has an adjustment range of 0-100%.

[0040] Multi-point pressure monitoring module Pressure sensor selection: A miniature strain gauge pressure sensor (model: MSP300) is adopted, with a measurement range of 0-100cmH2O, an accuracy of ±0.5cmH2O, a response time of ≤10ms, a power supply voltage of 5V, and an output signal of 0-5V analog signal. The sensor has dimensions of Φ5mm×10mm and a weight of ≤2g, making it easy to install in confined surgical fields.

[0041] The sealing plug is integrally molded from medical-grade silicone rubber and contains a sterile filter membrane (0.22μm pore size) with a filtration efficiency of ≥99.9%. This prevents blood or tissue fluid from entering the sensor without affecting the transmission of pressure signals. The signal transmission cable is a shielded twisted-pair cable with a diameter of 0.3mm and a length of 1.5m. The shielding layer is a tinned copper wire braided mesh, providing a shielding effect of ≥85dB and reducing electromagnetic interference.

[0042] Flow regulation module Electro-proportional valve selection: A direct-acting electromagnetic proportional valve (model: EPV-01) is adopted, with a flow rate adjustment range of 10-200 mL / min, an adjustment accuracy of ±2 mL / min, a valve opening adjustment range of 0-100%, a power supply voltage of 12V, and a control signal of 0-5V analog or pulse signal. The valve port is sealed with alumina ceramic, which is wear-resistant and corrosion-resistant, and the leakage is ≤0.1 mL / min in an environment of 4-8℃.

[0043] The drive unit uses a stepper motor drive module (model: DM542), compatible with a two-phase hybrid stepper motor (model: 42HS40-1704), with a step angle of 1.8°, microstepping up to 256 microsteps, and an adjustable output current of 0.5-4.0A. The drive module features overcurrent protection (protection current 4.5A), overvoltage protection (protection voltage 28V), and overheat protection (protection temperature 85℃) to ensure safe operation.

[0044] The flow rate detection element uses an ultrasonic Doppler flow rate sensor (model: UFS-02), with a measurement range of 10-200 mL / min, a measurement error of ≤3%, a power supply voltage of 5V, an output signal of 0-5V analog signal, and an operating frequency of 2MHz. The sensor is installed using a clamp-on method, fixed to the outside of the flow sensing channel by a flexible clamp, which is convenient to install and does not affect the pipeline's sealing performance.

[0045] Real-time feedback control module The microcontroller uses an STM32F407VET6 microcontroller, based on the ARM Cortex-M4 core, with a main frequency of 168MHz, 1MB Flash and 192KB RAM, and has rich peripheral interfaces (including 3 ADCs, 2 DACs, multiple UARTs, I2C and SPI interfaces), which can meet the needs of multi-sensor signal processing and control algorithm execution.

[0046] The signal conditioning circuit employs a second-order active low-pass filter, consisting of an operational amplifier (model: OPA2376), resistors, and capacitors, with a cutoff frequency of 10Hz, effectively filtering out high-frequency noise in the sensor signal. The amplification circuit uses an instrumentation amplifier (model: INA128), with the amplification factor adjusted via a software-controlled digital potentiometer (model: AD5242) ranging from 1 to 100 times, ensuring accurate detection of weak signals. The analog-to-digital conversion utilizes a 16-bit ADC built into the microcontroller, with a sampling rate of 100Hz and a conversion accuracy of ±1LSB.

[0047] The control algorithms for the threshold comparison unit and the adjustment command generation unit are implemented using C language programming. The proportional coefficient (Kp), integral coefficient (Ki), and derivative coefficient (Kd) of the PID control algorithm can be adaptively adjusted according to the actual clinical situation to ensure the stability and speed of control. The communication interface circuit uses the MAX485 chip to implement RS485 communication for data transmission with the data storage and analysis module and the human-machine interaction module. The communication baud rate is 9600bps, and the data transmission distance is ≤10m.

[0048] Data storage and analysis module The storage unit uses an SD card module (model: MicroSD card module), which supports a maximum of 32GB MicroSD card. The data storage format is CSV and Excel. Each data record includes information such as timestamp (accurate to milliseconds), pressure data, flow data, temperature data, and valve opening data. Each record is approximately 32 bytes long. A 16GB SD card can store approximately 5 million records, meeting the storage needs of more than 1,000 perfusion data.

[0049] The embedded algorithms in the data analysis unit include data statistics algorithms (calculating average, maximum, minimum, standard deviation, etc.), curve fitting algorithms (fitting pressure-time and flow-time curves using the least squares method), and correlation analysis algorithms (analyzing the correlation between infusion parameters and infusion effectiveness based on Pearson correlation coefficient). These algorithms are implemented using C programming, run on a microcontroller, and process the stored data in real time to generate reports.

[0050] Data encryption employs the AES-256 encryption algorithm to encrypt each stored data record. The encryption key is stored in the microcontroller's Flash memory and protected by a password to prevent key leakage. The data backup function supports automatic data backup to a backup partition on the SD card. If the primary partition data is corrupted, data can be restored from the backup partition.

[0051] Human-computer interaction module The touchscreen display is a 7-inch color LCD touchscreen (model: TFT7004) with a resolution of 1024×600 and a brightness of ≥500cd / m². 2 With a contrast ratio of 1000:1, multi-touch support, a response time of ≤10ms, and an operating temperature range of 0-50℃, it meets the environmental requirements of operating rooms. The display's driver module uses an ILI9341 controller, communicating with the microcontroller via an SPI interface, resulting in fast data transmission and clear display.

[0052] The physical buttons use tactile switches (model: TS-1185) with an operating life of ≥100,000 cycles. The emergency stop button has normally closed contacts, disconnecting the circuit upon pressing to ensure reliability in emergencies. The buzzer uses a passive buzzer (model: FMQ-270) with a working voltage of 5V and a volume ≥85dB (at a distance of 1m). The volume can be adjusted via software (with 3 levels: low, medium, and high). The LED indicator uses high-brightness LEDs with red (alarm), green (normal operation), and yellow (filling complete) light intensity ≥2000mcd, ensuring clear visibility in a bright operating room environment.

[0053] Temperature monitoring module The temperature sensor uses a PT100 platinum resistance temperature sensor (model: PT100-316L), packaged in a stainless steel housing (3mm diameter, 10mm length), with a measurement range of 0-40℃, an accuracy of ±0.2℃, and a response time ≤50ms. The perfusion fluid temperature sensor is directly inserted into the pre-drilled hole in the reservoir and fixed with sealant to ensure full contact with the perfusion fluid; the lung surface temperature sensor is a patch type (10mm×10mm×2mm), with a medical pressure-sensitive adhesive (model: 3M 1522) coated on the back, ensuring firm adhesion and no irritation to lung tissue.

[0054] The temperature signal processing unit uses an instrumentation amplifier INA128 and an analog-to-digital converter ADS1115 (16-bit). The ADS1115 communicates with the microcontroller via an I2C interface, with a sampling rate of 10Hz and a conversion accuracy of ±0.01℃, ensuring the accuracy of the temperature data.

[0055] (II) System Assembly and Debugging System Assembly First, the core circuits of the real-time feedback control module, data storage and analysis module, and human-computer interaction module are soldered onto the PCB board and tested for power-on to ensure that the circuit connections of each module are normal and there are no short circuits or open circuits. Then, the PCB board is installed inside the main unit casing. The main unit casing is made of ABS engineering plastic injection molding with an antibacterial surface treatment. Its dimensions are 30cm×20cm×10cm, and its weight is ≤3kg, making it easy to move and place.

[0056] The touchscreen display is mounted on the front of the main unit casing, the physical buttons are located below the display, and the buzzer and LED indicator lights are mounted on the top of the main unit casing. The power module (input 220V AC, output 5V DC, 12V DC) is installed inside the main unit to power all modules. The power module has overvoltage protection, overcurrent protection, and short circuit protection functions, and the output voltage accuracy is ±5%.

[0057] Connect the integrated disposable infusion tubing assembly to the main unit: insert the pressure sensor's signal transmission cable into the main unit's sensor interface, connect the electronically controlled proportional valve's drive interface to the main unit's drive output interface, and insert the temperature sensor's cable into the main unit's temperature interface. During connection, ensure the interfaces are firmly inserted and properly sealed to avoid signal interference or poor power contact.

[0058] System debugging (1) Sensor calibration Calibrate the pressure sensor: Connect the pressure sensor to a standard pressure source (accuracy ±0.1cmH2O), input pressures of 0, 20, 40, 60, 80, and 100cmH2O in sequence, record the sensor's output signal, and adjust the calibration coefficient through software to make the sensor's measured value consistent with the output value of the standard pressure source. The error after calibration should be ≤0.5cmH2O.

[0059] Calibrate the flow rate detection element: Flow liquid at known flow rates (10, 50, 100, 150, 200 mL / min) into the integrated disposable infusion tubing assembly using a peristaltic pump, record the output signal of the flow rate detection element, and adjust the calibration coefficient so that the error between the measured value and the actual flow rate is ≤3%.

[0060] Calibrate the temperature sensor: Place the temperature sensor in a constant temperature water bath and set the temperature sequentially to 0℃, 10℃, 20℃, 30℃, and 40℃. Record the sensor's output signal and adjust the calibration coefficient so that the error between the measured value and the set temperature of the constant temperature water bath is ≤0.2℃.

[0061] (2) Control Algorithm Debugging: Under simulated perfusion conditions (using a simulated lung model with adjustable pulmonary vascular resistance), the automatic control performance of the system was tested. The pressure threshold was set to 10-30 cmH2O, and the flow rate threshold was set to 50-100 mL / min. The pressure and flow rate regulation responses of the system were observed by adjusting the vascular resistance of the simulated lung model. When the vascular resistance increased, causing the pulmonary artery pressure to rise to 35 cmH2O, the system should adjust the opening of the electronically controlled proportional valve within 1 second to reduce the pressure to below 30 cmH2O and stabilize the flow rate within the set range. When the vascular resistance decreased, causing the pressure to drop to 8 cmH2O, the system should increase the valve opening within 1 second to raise the pressure to above 10 cmH2O, ensuring the speed and stability of the control algorithm.

[0062] (3) Alarm function debugging: Simulate various fault conditions to test the system's alarm function: Overpressure alarm: When a pressure of 35 cmH2O is input to the pressure sensor through a standard pressure source, the system should immediately trigger a first-level alarm, with the buzzer sounding, the LED flashing red, and the display showing "Pulmonary artery pressure too high".

[0063] Low flow alarm: If the pipeline is blocked and the flow rate drops below 20 mL / min, the system will trigger a level one alarm and display "Pipeline blocked, flow rate too low".

[0064] Over-temperature alarm: When the infusion fluid temperature sensor is placed in water at 30℃, the system triggers a level two alarm, the buzzer sounds, the LED flashes red, and the display shows "Infusion fluid temperature too high".

[0065] Sensor fault alarm: Disconnecting the pressure sensor cable triggers a level two alarm, displaying "Pressure sensor fault".

[0066] All alarm functions should be accurate and timely, and alarm information should be clear and easy to understand.

[0067] (4) Data Storage and Analysis: Conduct a simulated infusion operation for 30 minutes. The system should store data such as pressure, flow rate, and temperature in real time, and the timestamps of the stored data should be accurate (error ≤ 1ms). After the infusion is completed, view the curves, charts, and reports on the data query interface. The curves should be continuous and smooth, with no data loss or abnormal fluctuations, and the statistical data in the reports (such as average pressure and total infusion volume) should be calculated accurately. Export the data to a USB flash drive. The exported CSV file should be able to be opened normally in Excel, and the data format should be correct.

[0068] (III) Examples of Clinical Application The following examples, presented in conjunction with specific clinical cases, illustrate the application of the system of this invention in the perfusion process prior to donor lung retrieval: Case: Male donor, age 45, brain dead, height 175cm, weight 70kg, no history of lung disease, meets the criteria for lung donation.

[0069] Preoperative preparation Medical staff removed the integrated disposable perfusion tubing assembly, checked it for integrity, and connected the perfusion fluid inlet to the perfusion bag containing 4°C perfusion fluid (Perfadex solution, with 125 μg of PGE1 per liter). The perfusion bag was suspended 30 cm above the operating table. The lung connection was connected to the pulmonary artery cannula (18Fr), and the drainage channel was connected to the left atrial drainage tube. The pressure sensor was connected to the pressure tap, and the lung surface temperature sensor was attached to the surface of the right lung.

[0070] After the system host is turned on and the self-test is passed, enter the parameter setting interface, input the case information, and set the parameters: pulmonary artery pressure threshold 10-30cmH2O, perfusion flow rate threshold 50-80mL / min (based on a body weight of 70kg, the total perfusion volume is calculated at 50-60mL / kg, which is 3500-4200mL, so set the total perfusion volume to 4000mL), perfusion fluid temperature threshold ≤6℃, lung surface temperature threshold ≤8℃, and perfusion time upper limit 30 minutes.

[0071] Infusion process Select automatic mode and start the perfusion operation. The system opens the electronically controlled proportional valve, and the perfusion fluid begins to flow into the donor lung. The real-time monitoring interface displays: initial pulmonary artery inlet pressure 15 cmH2O, distal pulmonary artery pressure 12 cmH2O, left atrial pressure 5 cmH2O, transpulmonary pressure gradient 10 cmH2O, pulmonary vascular resistance 0.2 cmH2O / (mL・min), perfusion flow rate 65 mL / min, perfusion fluid temperature 4.2℃, lung surface temperature 6.5℃. The system is operating normally, and the green LED indicator light remains constantly lit.

[0072] Ten minutes after perfusion, due to a slight increase in pulmonary vascular resistance, the pulmonary artery inlet pressure rose to 32 cmH2O, exceeding the upper limit threshold. The system immediately triggered a Level 1 alarm, with a buzzer sounding, a flashing red LED, and the display showing "Pulmonary Artery Pressure Too High." Simultaneously, the real-time feedback control module automatically adjusted the opening of the electronically controlled proportional valve, reducing the flow rate from 65 mL / min to 55 mL / min. One second later, the pulmonary artery inlet pressure dropped to 28 cmH2O, the alarm was deactivated, and the system returned to normal operation.

[0073] Twenty minutes after perfusion, the left atrial drainage fluid gradually became clear, and the lung surface color turned a uniform pale white, indicating good perfusion effect. At this time, the monitoring data were as follows: pulmonary artery inlet pressure 25 cmH2O, distal pulmonary artery pressure 20 cmH2O, left atrial pressure 6 cmH2O, transpulmonary pressure gradient 19 cmH2O, pulmonary vascular resistance 0.35 cmH2O / (mL・min), perfusion flow rate 56 mL / min, perfusion fluid temperature 4.0℃, and lung surface temperature 7.2℃. All parameters were within the preset range.

[0074] Thirty minutes after the infusion was completed, the total infusion volume reached 4000 mL. The system automatically closed the electronically controlled proportional valve, stopped the infusion, emitted a buzzer, flashed a yellow LED indicator, and displayed "Infusion Complete." Medical staff then closed the infusion bag, disconnected the tubing, removed the integrated disposable infusion tubing assembly (for disposal), separated the donor lung from the heart, and prepared for the subsequent transplant surgery.

[0075] After data recording and analysis of the perfusion, medical staff viewed detailed data on the data query interface: mean pulmonary artery inlet pressure 22 cmH2O, mean flow rate 60 mL / min, maximum transpulmonary pressure gradient 20 cmH2O, mean pulmonary vascular resistance 0.3 cmH2O / (mL・min), total perfusion volume 4000 mL, mean perfusion fluid temperature 4.1℃, and mean lung surface temperature 6.8℃. The graphs showed stable pressure and flow rates without significant fluctuations, and the perfusion parameters met clinical requirements. The data was exported to the hospital information system for subsequent case analysis and quality traceability.

[0076] Postoperative follow-up: The recipient patient's transplant surgery was successful. 72 hours after the operation, the oxygenation index was 380 mmHg, no PGD occurred, and lung function recovered well, indicating that the donor lung was effectively protected during perfusion. The system of this invention significantly improves the perfusion quality.

[0077] The flow and pressure monitoring and control system for the pre-donor lung retrieval perfusion process of the present invention can be flexibly adjusted according to different clinical needs in practical applications. For example, for donors with smaller body weight, an integrated disposable perfusion tubing assembly with a smaller inner diameter can be selected, and the flow threshold range can be adjusted; for donors with mild lung injury, the pressure threshold and flow threshold can be appropriately reduced to avoid aggravating lung injury.

[0078] The materials used in integrated disposable infusion tubing assemblies can also be selected from other medical-grade materials, such as medical-grade silicone, as long as they meet requirements for biocompatibility, low-temperature flexibility, and sealing performance. The number of pressure taps can also be increased according to clinical monitoring needs, such as adding pulmonary vein pressure taps to further enrich pressure monitoring data.

[0079] In addition to PID control, the real-time feedback control module can also employ other advanced control algorithms such as fuzzy control and adaptive control, as long as precise regulation of pressure and flow can be achieved. The data storage and analysis module can also utilize cloud storage to enable multi-center data sharing and collaborative analysis.

[0080] Furthermore, the system of this invention can also interact with the hospital's HIS system and laboratory information system (LIS) to achieve integrated management of patient information, perfusion data, and postoperative follow-up data, providing more comprehensive data support for clinical research and treatment decisions.

[0081] In summary, the flow and pressure monitoring and control system for the pre-donor lung perfusion process of the present invention effectively solves many defects of the prior art through integrated design, precise monitoring and dynamic feedback control, significantly improves the safety, effectiveness and standardization of donor lung perfusion, and has important clinical application value and promotion prospects.

Claims

1. A flow and pressure monitoring and control system for the perfusion process before donor lung retrieval, characterized in that, The system includes an integrated disposable perfusion tubing assembly, a multi-point pressure monitoring module, a flow regulation module, a real-time feedback control module, a data storage and analysis module, and a human-machine interface module. The integrated disposable perfusion tubing assembly includes an infusion fluid input end, a built-in pressure tap, a flow sensing channel, an electronically controlled proportional valve mounting cavity, a lung connection end, and a drainage channel. At least three built-in pressure taps are provided, corresponding to the pulmonary artery inlet, distal pulmonary artery, and left atrial location, respectively. The electronically controlled proportional valve mounting cavity is used to fix the disposable electronically controlled proportional valve actuator. The multi-point pressure monitoring module is sealed to the built-in pressure taps via pressure sensors, and is used to collect pressure data from different locations in real time. The data is transmitted to the real-time feedback control module. The flow regulation module includes an electronically controlled proportional valve, a drive unit, and a flow velocity detection element. The flow velocity detection element is located in the flow sensing channel and is used to detect the perfusion fluid flow rate in real time. The real-time feedback control module is electrically connected to the multi-point pressure monitoring module, the flow regulation module, the data storage and analysis module, and the human-machine interaction module. Based on the pressure data, flow velocity data, and preset lung function index thresholds, it automatically generates flow and pressure regulation commands and sends them to the flow regulation module. The data storage and analysis module is used to synchronously store key parameters such as pressure, flow rate, perfusion time, and total perfusion volume. The human-machine interaction module is used for parameter setting, data display, and alarm prompts.

2. The flow and pressure monitoring and control system for the pre-donor lung retrieval perfusion process according to claim 1, characterized in that, The integrated disposable infusion tubing assembly is integrally injection molded from medical-grade polyvinyl chloride or thermoplastic elastomer material. The inner wall of the tubing is coated with an ultra-slippery antibacterial coating. The infusion fluid input end is equipped with a Luer locking connector and has a built-in one-way valve to prevent infusion fluid backflow.

3. The flow and pressure monitoring and control system for the pre-donor lung harvesting perfusion process according to claim 1, characterized in that, The pressure sensor of the multi-point pressure monitoring module is a miniature strain gauge pressure sensor with a measurement range of 0-100cmH2O, an accuracy of ±0.5cmH2O, and a response time of ≤10ms. The pressure sensor and the built-in pressure tap are detachably connected through a sterile sealing plug, and a leak-proof gasket is provided at the connection.

4. The flow and pressure monitoring and control system for the pre-donor lung retrieval perfusion process according to claim 1, characterized in that, The flow regulation module uses a direct-acting electromagnetic proportional valve with a flow regulation range of 10-200 mL / min and an adjustment accuracy of ±2 mL / min. The drive unit is a stepper motor drive module that controls the valve opening of the electronically controlled proportional valve through pulse signals. The flow velocity detection element uses an ultrasonic Doppler flow velocity sensor with a measurement error ≤3%.

5. The flow and pressure monitoring and control system for the pre-donor lung retrieval perfusion process according to claim 1, characterized in that, The real-time feedback control module includes a microcontroller, a signal conditioning circuit, a threshold comparison unit, and an adjustment command generation unit. The signal conditioning circuit is used to filter, amplify, and perform analog-to-digital conversion on the analog signals output by the pressure sensor and the flow velocity detection element. The threshold comparison unit compares the processed pressure data and flow velocity data with preset safety thresholds. The adjustment command generation unit generates an electronically controlled proportional valve opening adjustment command based on the comparison results and the calculation results of transpulmonary pressure difference and pulmonary vascular resistance.

6. The flow and pressure monitoring and control system for the pre-donor lung retrieval perfusion process according to claim 5, characterized in that, The transpulmonary pressure gradient is calculated by the difference between the pulmonary artery inlet pressure and the left atrial pressure. The pulmonary vascular resistance is calculated by the ratio of the transpulmonary pressure gradient to the perfusion flow rate. The preset safety thresholds include the maximum perfusion pressure threshold, the minimum perfusion pressure threshold, the maximum flow rate threshold, and the minimum flow rate threshold, and the thresholds can be modified through the human-computer interaction module.

7. The flow and pressure monitoring and control system for the pre-donor lung retrieval perfusion process according to claim 1, characterized in that, The data storage and analysis module includes a storage unit and a data analysis unit. The storage unit uses an SD card or a solid-state drive and stores data including real-time pressure data, real-time flow data, adjustment command data, infusion start time, infusion end time, and total infusion volume. The storage format supports CSV and Excel. The data analysis unit can perform statistical analysis on the stored data and generate infusion process curves and key parameter reports.

8. The flow and pressure monitoring and control system for the pre-donor lung harvesting perfusion process according to claim 1, characterized in that, The human-machine interaction module includes a touch screen, physical buttons, and an audible and visual alarm device. The touch screen is used to display real-time monitoring data, preset parameters, and system status. The physical buttons are used for emergency shutdown, parameter confirmation, and mode switching. The audible and visual alarm device triggers an alarm when the pressure or flow exceeds a preset threshold, or when there is a sensor malfunction or pipeline blockage.

9. The flow and pressure monitoring and control system for the pre-donor lung retrieval perfusion process according to claim 1, characterized in that, It also includes a temperature monitoring module, which comprises a temperature sensor and a temperature signal processing unit. The temperature sensor is located at the infusion fluid input end and the lung connection end of the integrated disposable infusion tubing assembly, and is used to detect the infusion fluid temperature and lung surface temperature in real time. The detection range is 0-40℃, and the accuracy is ±0.2℃. The temperature signal processing unit transmits the temperature data to the real-time feedback control module. When the temperature exceeds the preset range, the real-time feedback control module controls the human-machine interaction module to sound an alarm.

10. The flow and pressure monitoring and control system for the pre-donor lung harvesting perfusion process according to claim 1, characterized in that, The integrated disposable infusion pipeline assembly also includes a liquid storage chamber and a defoaming device. The liquid storage chamber is located between the infusion liquid inlet and the flow sensing channel, and has a volume of 50-100mL. The defoaming device adopts a centrifugal defoaming structure and is located between the liquid storage chamber and the electronically controlled proportional valve mounting chamber to remove air bubbles from the infusion liquid.

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