Method and system for dynamically adjusting displacement liquid flow and hemodiafiltration device

Abstract

The invention discloses a method and system for dynamically adjusting displacement liquid flow and a hemodiafiltration device.The method comprises the following steps that the initial pre-displacement liquid flow and the initial post-displacement liquid flow are determined, transmembrane pressure is monitored in real time, and a control system controls the displacement liquid flow to be dynamically adjusted according to the degree that the transmembrane pressure deviates from a target range. The self-adaptive adjustment step length of the displacement liquid flow is calculated through a feedback control algorithm, the front displacement liquid flow and the rear displacement liquid flow are dynamically adjusted according to the self-adaptive adjustment step length, and dynamic and fine adjustment of the front displacement liquid flow and the rear displacement liquid flow is achieved. The TMP is stably controlled within a safe range by dynamically adjusting the front and rear displacement liquid flows and utilizing a dynamic step length adjusting mechanism, so that the excessive concentration of blood in the dialyzer is effectively reduced, the blood coagulation risk of the dialyzer is reduced, and the service life of the dialyzer is prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of hemodiafiltration, and in particular to a method and system for dynamically regulating the flow rate of a replacement fluid. Background Art

[0002] Hemodiafiltration (HDF) is an advanced blood purification technology that removes uremic toxins of various molecular weights from the blood through a combination of diffusion and convection. Compared to traditional hemodialysis (HD), HDF offers significant advantages in removing medium and large molecular weight toxins, potentially improving patients' long-term survival and quality of life. Depending on the location of replacement fluid injection, HDF can be categorized into three modes: pre-dilution, post-dilution, and mixed-dilution. Pre-dilution, in which replacement fluid is added before the blood enters the dialyzer, offers the advantages of reducing hemoconcentration and the risk of clotting. However, due to the dilution of the blood, convective clearance efficiency is reduced. Post-dilution, in which replacement fluid is added after the blood passes through the dialyzer, offers high convective clearance efficiency but is prone to hemoconcentration and dialyzer clotting, and the replacement fluid flow rate is significantly limited by blood flow. Mixed-dilution HDF, in which replacement fluid is injected simultaneously at both the front and rear ends of the dialyzer, combines the advantages of both pre-dilution and post-dilution. Dialysis technology in Europe and the United States primarily utilizes post-dilution HDF, which typically results in higher blood flow rates (averaging approximately 350 ml / min). In contrast, Japan primarily utilizes pre-dilution HDF, which results in lower blood flow rates (approximately 200 ml / min to 220 ml / min). Chinese patients' vascular conditions and physical characteristics fall somewhere in between these two approaches, making the mixed-dilution HDF model more suitable.

[0003] The existing technical solutions have the following problems: The pre- and post-replacement fluid flow parameters are static and lack real-time response. Existing technologies tend to set fixed pre- and post-replacement ratios or flow rates based on experience, which is insufficiently responsive to TMP changes caused by factors such as hemodynamic fluctuations, changes in hemoconcentration, and dialyzer filtration coefficient attenuation. The response mechanism after the TMP over-limit alarm is passive and the adjustment step size is fixed and rough: the TMP management of existing technologies is mainly based on upper and lower limit alarms. When the TMP monitoring value exceeds the preset safety threshold, the system usually issues an alarm prompt. Some more advanced technologies may perform automatic adjustments, such as trying to reduce TMP by reducing part of the pre-replacement fluid flow or post-replacement fluid flow. However, a significant shortcoming of this automatic adjustment mechanism is that it often adopts a preset, fixed-size adjustment step size (for example, 10 ml / min each adjustment). This fixed-step adjustment method often makes the adjustment force too large or insufficient, forcing the system into a long cycle of repeated attempts, and unable to achieve efficient and accurate adjustment. Summary of the Invention

[0004] The purpose of the present invention is to address the problems of coarseness, fixed step size and lack of dynamic adaptability of TMP feedback adjustment in the current existing technology, and to provide a method, system and hemodiafiltration device for dynamically adjusting the replacement fluid flow rate. By monitoring the transmembrane pressure in real time and dynamically calculating the replacement fluid flow adjustment step size, dynamic and refined adjustment of the ratio of the front replacement fluid flow rate to the rear replacement fluid flow rate is achieved to maintain the optimal transmembrane pressure state and avoid coagulation or decreased clearance efficiency caused by excessive blood concentration (transmembrane pressure is too high) or dilution (transmembrane pressure is too low).

[0005] The technical solutions of the present invention are as follows: A method for dynamically adjusting the flow rate of a replacement fluid comprises the following steps: Determine the initial front replacement fluid flow rate and the initial back replacement fluid flow rate, monitor the transmembrane pressure in real time, and the control system calculates the replacement fluid flow adaptive adjustment step size using a feedback control algorithm based on the degree to which the transmembrane pressure deviates from the target range, and dynamically adjusts the front replacement fluid flow rate and the back replacement fluid flow rate based on the adaptive adjustment step size.

[0006] Through this approach, the high-precision monitoring system provides real-time, continuous parameter data. The control system uses this data as input to feedback control algorithms, such as calculating real-time TMP and effective blood flow, and based on this real-time data, online calculates and adjusts the flow settings of each pump.

[0007] Furthermore, the control system uses a piecewise linear function to calculate the adaptive adjustment step size : , in, Indicates the dynamic adjustment step of the replacement fluid flow rate, Indicates the minimum adjustment step, ranging from 3ml / min to 7ml / min; Indicates the maximum adjustment step, ranging from 18ml / min to 22ml / min; Indicates the transmembrane pressure deviation, Indicates the upper limit of transmembrane pressure deviation, ranging from 40mmH to 60mmH.

[0008] Furthermore, the feedback control algorithm includes an initial pre-substitution fluid flow algorithm, an initial post-substitution fluid flow algorithm, and a transmembrane pressure dynamic feedback algorithm; the transmembrane pressure dynamic feedback algorithm includes the following steps: Set the total displacement conservation constraint so that the total displacement remains constant during any adjustment: , in, is the total replacement fluid flow, is the flow rate of the replacement fluid before, is the post-displacement fluid flow rate; Set TMP feedback adjustment rules: When the TMP is increased, the blood concentration can be increased by reducing the flow rate of the replacement fluid before and increasing the flow rate of the replacement fluid after: , , , to prevent the front replacement fluid flow from being negative; in, represents the transmembrane pressure, Indicates the lower threshold of transmembrane pressure, Indicates the dynamic adjustment step of the replacement fluid flow rate, Indicates the replacement fluid flow adjustment step, Adaptively adjust the step size according to the degree to which TMP deviates from the threshold ; when When the TMP is reduced, the blood concentration can be reduced by reducing the post-replacement fluid flow and increasing the pre-replacement fluid flow: , , , to prevent the post-displacement fluid flow from being negative; in, Indicates the upper threshold of transmembrane pressure; when When the flow rate of the replacement fluid is maintained unchanged.

[0009] Through the above method, a TMP dynamic adaptive adjustment step algorithm was established. According to the deviation degree, deviation rate and even trend of the real-time monitored TMP value from the target range, a feedback control algorithm was introduced to dynamically calculate the adjustment step of the pre-displacement and post-displacement fluid flow rates that need to be adjusted ( ), rather than using a fixed adjustment step size; when TMP deviates seriously, the algorithm calculates a larger With fast correction, when TMP approaches the target range, the algorithm calculates a smaller Fine-tuning allows for faster, more stable, and more precise TMP control that far exceeds existing technology.

[0010] Furthermore, the initial pre-substitution fluid flow rate algorithm and the initial post-substitution fluid flow rate algorithm include the following steps: Calculate plasma water flow rate : , in, is the effective blood flow, is the hematocrit; The ratio of water to plasma components ranges from 90% to 95%; Calculate total replacement fluid flow : , in, represents the displacement coefficient, ranging from 0.7 to 1.0; Calculation of replacement fluid flow rate : , in, is the dehydration rate; Set a value for the filtration fraction, ranging from 0.3 to 0.5; is the filtration fraction, and ; Calculate the replacement fluid flow rate : .

[0011] Furthermore, the control system collects TMP data in real time and executes a feedback control algorithm according to a preset feedback adjustment cycle of 5 minutes to 10 minutes. The rapid adjustment cycle is combined with the dynamic step size to make the system respond more promptly to TMP changes.

[0012] Furthermore, the control system is provided with a safety boundary and an alarm module. or , the displacement flow rate will be forced to be set to 0 and an alarm will be issued.

[0013] The present application also includes a system for dynamically adjusting the flow rate of a replacement fluid, comprising: Blood circulation module: including blood pump, arterial bottle, venous bottle, blood pipeline and dialyzer; Replacement fluid module: including replacement fluid preparation unit, front replacement pump, rear replacement pump and related pipelines; Dialysis fluid module: includes dialysate preparation unit, ultrafiltration pump and related pipelines; Monitoring system: including pressure sensor, temperature sensor, and hematocrit sensor; Control system: includes main control unit, feedback control algorithm module, human-computer interaction interface, safety boundary and alarm module.

[0014] Through this system, the high-precision monitoring system provides real-time, continuous parameter data. The control system uses this data as input to feedback control algorithms, such as calculating real-time TMP and effective blood flow, and based on this real-time data, online calculates and adjusts the flow settings of each pump.

[0015] Furthermore, the feedback control algorithm module includes an initial front replacement fluid flow algorithm, an initial rear replacement fluid flow algorithm and a transmembrane pressure dynamic feedback algorithm; the initial front replacement fluid flow algorithm and the initial rear replacement fluid flow algorithm determine the initial front replacement fluid flow and the rear replacement fluid flow according to the hematocrit, the effective blood flow and the dehydration rate; the transmembrane pressure dynamic feedback algorithm dynamically adjusts the front replacement fluid flow and the rear replacement fluid flow according to the transmembrane pressure in real time, not only adjusting according to the TMP deviation direction, but also dynamically calculating the step length required for each adjustment of the replacement fluid flow according to the degree of deviation .

[0016] Furthermore, the transmembrane pressure dynamic feedback algorithm includes the following steps: Set the total displacement conservation constraint so that the total displacement remains constant during any adjustment: , in, is the total replacement fluid flow, is the flow rate of the replacement fluid before, is the post-displacement fluid flow rate; Set TMP feedback adjustment rules: When the TMP is increased, the blood concentration can be increased by reducing the flow rate of the replacement fluid before and increasing the flow rate of the replacement fluid after: , , , to prevent the front replacement fluid flow from being negative; in, represents the transmembrane pressure, Indicates the lower threshold of transmembrane pressure, Indicates the dynamic adjustment step of the replacement fluid flow rate, Indicates the replacement fluid flow adjustment step, Adaptively adjust the step size according to the degree to which TMP deviates from the threshold ; when When the TMP is reduced, the blood concentration can be reduced by reducing the post-replacement fluid flow and increasing the pre-replacement fluid flow: , , , to prevent the post-displacement fluid flow from being negative; in, Indicates the upper threshold of transmembrane pressure; when When , the current replacement fluid flow rate remains unchanged; According to the degree of TMP deviation from the threshold, a piecewise linear function is used to adaptively adjust the step size. : , in, Indicates the dynamic adjustment step of the replacement fluid flow rate, Indicates the minimum adjustment step, ranging from 3ml / min to 7ml / min; Indicates the maximum adjustment step, ranging from 18ml / min to 22ml / min; Indicates the transmembrane pressure deviation, Indicates the upper limit of transmembrane pressure deviation, ranging from 40mmH to 60mmH.

[0017] Through the above system, a TMP dynamic adaptive adjustment step algorithm was established. According to the deviation degree, deviation rate and even trend of the real-time monitored TMP value from the target range, a feedback control algorithm was introduced to dynamically calculate the adjustment step of the front and rear replacement fluid flows ( ), rather than using a fixed adjustment step size; when TMP deviates seriously, the algorithm calculates a larger With rapid correction, when TMP approaches the target range, the feedback control algorithm calculates a smaller Fine-tuning allows for faster, more stable, and more precise TMP control that far exceeds existing technology.

[0018] The present application also includes a hemodiafiltration device, which uses a system for dynamically adjusting the flow rate of a replacement fluid to implement a method for dynamically adjusting the flow rate of a replacement fluid.

[0019] Compared with the existing technology, the beneficial effects of the present invention are: 1. Utilize three independently controlled pumps to achieve precise setting, independent regulation, and dynamic adjustment of the front and rear replacement fluid flows over a wide range; 2. By maintaining the optimal transmembrane pressure and fluid dynamics (TMP safety and high convection efficiency), the convection clearance efficiency is maximized and the clearance rate of medium and large molecular toxins is improved; 3. By dynamically adjusting the front-to-back replacement ratio and utilizing a dynamic step-size mechanism to stably control TMP within a safe range, the over-concentration of blood in the dialyzer can be effectively reduced, the risk of dialyzer coagulation can be lowered, and the service life of the dialyzer can be extended. 4. Simplify the operation process and significantly reduce the burden on operators. Core parameters (such as replacement fluid flow rate, front-to-back ratio, and adjustment step length) are calculated and dynamically adjusted by the system based on real-time data, significantly reducing the frequency and complexity of manual intervention by operators; BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 Flowchart of the present application method.

[0020] Figure 2 This is a system diagram of this application.

[0021] Figure markings: 1-arterial clamp, 2-blood oxygen monitoring block / blood volume monitoring block, 3-arterial air detection, 4-pre-pump arterial pressure monitoring (Pre-AP), 5-blood pump, 6-syringe pump, 7-post-pump arterial pressure monitoring (Post-AP), 8-blood filter, 9-venous pressure monitoring (VP), 10-venous pot liquid level monitoring, 11-venous pot, 12-venous air monitoring, 13-blood identification, 14-venous clamp, 15-replacement fluid interface, 16-fluid infusion clamp, 17-replacement fluid pump, 18-replacement fluid pump 2. DETAILED DESCRIPTION

[0022] It should be noted that relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus comprising the element.

[0023] In addition to the technical problems mentioned in the background technology, there are also the following problems: 1. Limitations of a single pre- and post-dilution mode: While the pre-dilution mode can reduce the risk of coagulation, it has low convective clearance efficiency. While the post-dilution mode has high clearance efficiency, it is prone to hemoconcentration and dialyzer clotting. A single mode cannot achieve both efficient clearance and low coagulation risk.

[0024] 2. Lack of flexibility and dynamism in the adjustment of pre- and post-dilution ratios: Existing mixed dilution systems rely on preset ratios or limited manual adjustments, and are unable to dynamically adjust the pre- and post-dilution ratios in real time, optimally, based on changes in coagulation risk, blood concentration, vascular conditions, blood characteristics, and dialyzer performance.

[0025] 3. Limited replacement fluid volume: In post-dilution mode, the replacement fluid volume is usually limited by blood flow (generally not exceeding 30% of blood flow), which limits the convective clearance efficiency. Although the replacement fluid volume can be larger in pre-dilution mode, the clearance efficiency is low due to the dilution effect.

[0026] 4. Dependence on manual intervention and complex operation: The system is not highly automated, especially lacking dynamic response to TMP fluctuations. This requires operators to frequently monitor and make manual adjustments, which places a heavy workload. Furthermore, the timeliness and accuracy of manual adjustments are difficult to guarantee and are easily affected by the operator's experience.

[0027] 5. Insufficient monitoring: There is a lack of real-time monitoring and dynamic response mechanism for changes in blood concentration status and transmembrane pressure, making it difficult to respond in a timely manner to problems such as excessively high or low transmembrane pressure leading to dialyzer coagulation or low clearance efficiency.

[0028] 6. Low efficiency in clearing medium and large molecular toxins: Since the replacement strategy cannot be dynamically adjusted according to parameters such as real-time TMP to compensate for the attenuation of dialyzer filtration performance or to respond to hemodynamic changes, the system cannot maintain the optimal fluid dynamics state, resulting in the failure to fully clear medium and large molecular toxins.

[0029] 7. The TMP feedback mechanism is outdated and has a fixed step length: This is the core bottleneck of existing technologies. When TMP is abnormal, existing systems mainly use alarm prompts; even if they have automatic adjustment, the step length used to adjust the replacement fluid flow is fixed. This fixed-step adjustment mechanism is not responsive enough to rapid and drastic changes in TMP, and the adjustment force is often too large or insufficient, forcing the system into a long cycle of repeated attempts, making it impossible to achieve efficient and accurate adjustment, and thus unable to maintain the TMP stably within the optimal safety range for fine control, which directly affects convection efficiency and coagulation risk management. The main problems are as follows: 1) Sluggish response: If the TMP deviates significantly from the target range, it takes multiple iterations to adjust the TMP in a fixed small step size to bring it back. This makes it impossible to achieve timely and effective control, especially when the dialyzer changes rapidly. 2) Excessive / Insufficient Adjustment: Using a large fixed step size can easily cause TMP to fluctuate repeatedly around the target value, resulting in a "hunting" phenomenon and making it difficult to stabilize within the optimal range; while a step size that is too small may lead to insufficient adjustment.

[0030] 3) Lack of refined control: The system cannot dynamically determine the required adjustment based on the magnitude and rate of TMP deviation from the target value. The same adjustment step size is used for both minor and major TMP deviations, making this adjustment strategy neither efficient nor precise.

[0031] 4) Increased operational burden and alarm frequency: Rough adjustments of fixed step sizes sometimes cause TMP to fluctuate back and forth near the threshold, which may frequently trigger alarms and require manual intervention by operators, increasing workload and reliance on operator experience.

[0032] The features and performance of the present invention are further described in detail below with reference to the embodiments.

[0033] See also Figure 1-2 , a method for dynamically regulating the replacement fluid flow rate, e.g. Figure 1 As shown, the following steps are included: Determine the initial front replacement fluid flow rate and the initial back replacement fluid flow rate, monitor the transmembrane pressure in real time, and the control system calculates the replacement fluid flow adaptive adjustment step size using a feedback control algorithm based on the degree to which the transmembrane pressure deviates from the target range, and dynamically adjusts the front replacement fluid flow rate and the back replacement fluid flow rate based on the adaptive adjustment step size.

[0034] Through this approach, the high-precision monitoring system provides real-time, continuous parameter data. The control system uses this data as input to feedback control algorithms, such as calculating real-time TMP and effective blood flow, and based on this real-time data, online calculates and adjusts the flow settings of each pump.

[0035] The control system collects TMP data in real time and executes the feedback control algorithm according to the preset feedback adjustment cycle of 5min to 10min. The fast adjustment cycle and dynamic step size make the system respond to TMP changes more timely. The control system is equipped with a safety boundary and an alarm module. If the adjustment or , the displacement flow rate will be forced to be set to 0 and an alarm will be issued.

[0036] The feedback control algorithm includes an initial pre-replacement fluid flow algorithm, an initial post-replacement fluid flow algorithm, and a transmembrane pressure dynamic feedback algorithm; the initial pre-replacement fluid flow algorithm and the initial post-replacement fluid flow algorithm determine the initial pre-replacement fluid flow and post-replacement fluid flow according to the hematocrit, effective blood flow, and dehydration rate; the transmembrane pressure dynamic feedback algorithm dynamically adjusts the pre-replacement fluid flow and post-replacement fluid flow according to the transmembrane pressure in real time, not only adjusting according to the TMP deviation direction, but also dynamically calculating the step length required for each adjustment of the replacement fluid flow according to the degree of deviation. .

[0037] The initial pre-replacement fluid flow rate algorithm and the initial post-replacement fluid flow rate algorithm include the following steps: Calculate plasma water flow rate : , set up 250ml / min, is 35%, is 90%, which is obtained by the calculation formula is 146.25ml / min, in, is the effective blood flow, which is calculated by blood flow and the unit is ml / min. is the hematocrit; The ratio of water to plasma components ranges from 90% to 95%; Calculate total replacement fluid flow : , set up is 1.0, and is obtained by the calculation formula is 146.25ml / min, in, represents the displacement coefficient, ranging from 0.7 to 1.0; Calculation of replacement fluid flow rate : , set up 10ml / min, is 0.45, is 146.25ml / min, FF is 1.07, and the formula is obtained is 84.65ml / min, in, is the dehydration rate; Set a value for the filtration fraction, ranging from 0.3 to 0.5; is the filtration fraction, and ; Calculate the replacement fluid flow rate : , The calculation formula can be obtained It is 61.60ml / min.

[0038] The transmembrane pressure dynamic feedback algorithm includes the following steps: Set the total displacement conservation constraint so that the total displacement remains constant during any adjustment: , in, is the total replacement fluid flow, is the flow rate of the replacement fluid before, is the post-displacement fluid flow rate; Set TMP feedback adjustment rules: When the TMP is increased, the blood concentration can be increased by reducing the flow rate of the replacement fluid before and increasing the flow rate of the replacement fluid after: , , , to prevent the front replacement fluid flow from being negative; in, represents the transmembrane pressure, Indicates the lower threshold of transmembrane pressure, which is 250 mmHg, the critical value for triggering the increase of replacement fluid flow operation; Indicates the dynamic adjustment step of the replacement fluid flow rate, Indicates the replacement fluid flow adjustment step, Adaptively adjust the step size according to the degree to which TMP deviates from the threshold ; when When the TMP is reduced, the blood concentration can be reduced by reducing the post-replacement fluid flow and increasing the pre-replacement fluid flow: , , , to prevent the post-displacement fluid flow from being negative; in, Indicates the upper threshold of transmembrane pressure, which is 300 mmHg, the critical value for triggering the increase of the front replacement fluid flow operation; when When , the current replacement fluid flow rate remains unchanged; According to the degree of TMP deviation from the threshold, a piecewise linear function is used to adaptively adjust the step size. : , in, Indicates the dynamic adjustment step of the replacement fluid flow rate, Indicates the minimum adjustment step, ranging from 3ml / min to 7ml / min; Indicates the maximum adjustment step, ranging from 18ml / min to 22ml / min; Indicates the transmembrane pressure deviation, Indicates the upper limit of transmembrane pressure deviation, ranging from 40mmH to 60mmH. Set the fluid exchange feedback adjustment cycle to 5 minutes and the transmembrane pressure threshold range to 250mmHg ~ 300mmHg. 5ml / min, 20ml / min, 50 mmHg, First, when the first feedback adjustment cycle arrives, let TMP be 200 mmHg. is 50 mmHg, and the replacement fluid adjustment step length formula is obtained is 20ml / min, and according to the TMP feedback adjustment rule, we can get is 64.65ml / min, is 81.60ml / min, When the next feedback adjustment cycle arrives, let TMP be 235 mmHg. is 15 mmHg, which is obtained according to the replacement fluid adjustment step formula is 16.25 ml / min, and according to the TMP feedback adjustment rule, we can get is 48.40ml / min, is 97.85ml / min, When the next feedback adjustment cycle arrives, let TMP be 245 mmHg. is 5 mmHg, and the replacement fluid adjustment step length formula is obtained is 8.75 ml / min, and according to the TMP feedback adjustment rule, we can get is 39.65ml / min, is 106.6ml / min, When the next feedback regulation cycle arrives, the TMP is set to 275 mmHg. Within the transmembrane pressure threshold range, the front replacement fluid flow rate and the rear replacement fluid flow rate remain unchanged. When the next feedback adjustment cycle arrives, let TMP be 310 mmHg. is 10 mmHg, and the replacement fluid adjustment step length formula is obtained is 12.50 ml / min, and according to the TMP feedback adjustment rule, we can get is 52.15ml / min, It is 94.10ml / min.

[0039] The front replacement fluid flow rate and the back replacement fluid flow rate are dynamically adjusted according to the feedback adjustment cycle preset by the control system. The flow adjustment step size is calculated in real time based on the deviation degree of transmembrane pressure each time to achieve adaptive adjustment of the replacement fluid flow rate. The replacement fluid step size adjusted each time is a dynamic value rather than a fixed value.

[0040] The core idea of ​​the dynamic step size adjustment algorithm: The greater the TMP deviation from the target range or the faster the deviation rate, the greater the required adjustment force (∆d); conversely, the smaller and slower the deviation, the smaller the adjustment step size. This design draws on the concepts of proportional, differential, or fuzzy control from control theory, but applies it to the calculation of the adjustment step size for the displacement fluid flow rate. The basis is as follows: Clinical experience: In clinical practice, when TMP rises rapidly and approaches the alarm limit, experienced operators will make larger adjustments (such as reducing the post-replacement fluid flow or increasing the pre-replacement fluid flow) to quickly reduce TMP; when TMP fluctuates only slightly, only minor adjustments will be made. The dynamic step size algorithm is an adjustment strategy based on the degree of deviation; Mathematical model agreement: The relationship between plasma filtration rate and TMP is not strictly linear, but generally, higher TMP indicates higher ultrafiltration resistance or hemoconcentration. Based on TMP's reflection of filtration status, a larger TMP deviation generally indicates a stronger change in filtration resistance or coagulation tendency, thus requiring more "forceful" intervention (∆d) to quickly correct the condition. System stability: Fine-tuning with small steps near the target value can reduce system oscillations near the target value (over-adjustment / insufficient adjustment force) and improve control stability. Response speed: When TMP deviates severely, a larger step size can bring TMP back to a safe range more quickly, reducing the exposure time to high TMP and lowering the risk of coagulation.

[0041] The present application also includes a system for dynamically adjusting the flow rate of the replacement fluid, such as Figure 2 Shown, including: Blood circulation module: including blood pump, arterial bottle, venous bottle, blood pipeline and dialyzer; Replacement fluid module: including replacement fluid preparation unit, front replacement pump, rear replacement pump and related pipelines; Dialysis fluid module: includes dialysate preparation unit, ultrafiltration pump and related pipelines; Monitoring system: including pressure sensor, temperature sensor, and hematocrit sensor; Control system: includes main control unit, feedback control algorithm module, human-computer interaction interface, safety boundary and alarm module.

[0042] The feedback control algorithm module includes an initial pre-replacement fluid flow algorithm, an initial post-replacement fluid flow algorithm, and a transmembrane pressure dynamic feedback algorithm; the initial pre-replacement fluid flow algorithm and the initial post-replacement fluid flow algorithm determine the initial pre-replacement fluid flow and post-replacement fluid flow according to the hematocrit, effective blood flow, and dehydration rate; the transmembrane pressure dynamic feedback algorithm dynamically adjusts the pre-replacement fluid flow and post-replacement fluid flow according to the transmembrane pressure in real time, not only adjusting according to the TMP deviation direction, but also dynamically calculating the step length required for each adjustment of the replacement fluid flow according to the degree of deviation. .

[0043] The transmembrane pressure dynamic feedback algorithm includes the following steps: Set the total displacement conservation constraint so that the total displacement remains constant during any adjustment: , in, is the total replacement fluid flow, is the flow rate of the replacement fluid before, is the post-displacement fluid flow rate; Set TMP feedback adjustment rules: When the TMP is increased, the blood concentration can be increased by reducing the flow rate of the replacement fluid before and increasing the flow rate of the replacement fluid after: , , , to prevent the front replacement fluid flow from being negative; in, represents the transmembrane pressure, Indicates the lower threshold of transmembrane pressure, Indicates the dynamic adjustment step of the replacement fluid flow rate, Indicates the replacement fluid flow adjustment step, Adaptively adjust the step size according to the degree to which TMP deviates from the threshold ; when When the TMP is reduced, the blood concentration can be reduced by reducing the post-replacement fluid flow and increasing the pre-replacement fluid flow: , , , to prevent the post-displacement fluid flow from being negative; in, Indicates the upper threshold of transmembrane pressure; when When , the current replacement fluid flow rate remains unchanged; According to the degree of TMP deviation from the threshold, a piecewise linear function is used to adaptively adjust the step size. : , in, Indicates the dynamic adjustment step of the replacement fluid flow rate, Indicates the minimum adjustment step, ranging from 3ml / min to 7ml / min; Indicates the maximum adjustment step, ranging from 18ml / min to 22ml / min; Indicates the transmembrane pressure deviation, Indicates the upper limit of transmembrane pressure deviation, ranging from 40mmH to 60mmH.

[0044] The present application also includes a hemodiafiltration device, which uses a system for dynamically adjusting the flow rate of a replacement fluid to implement a method for dynamically adjusting the flow rate of a replacement fluid.

[0045] Through the method and system, the following effects are achieved: 1) Innovative setting of "dynamic adaptive adjustment step size of TMP": Breaking through the traditional fixed step size mode, the dynamic step size adjustment strategy is adopted to completely solve the response lag, excessive / insufficient adjustment force and stability defects caused by the fixed step size, and achieve rapid convergence and precise and stable control of TMP.

[0046] 2) Independently controlled three-pump system: enables precise control of front and rear replacement fluids and greater adaptability.

[0047] 3) Dynamic adjustment function: Automatically optimize the pre- and post-replacement fluid flows based on parameters such as hematocrit, effective blood flow, dehydration rate, and transmembrane pressure.

[0048] 4) Higher clearance rate of medium and large molecules: The mixed dilution mode combines the advantages of front and back dilution to improve the clearance efficiency of medium and large molecule toxins such as β2-microglobulin.

[0049] 5) Reduce the risk of coagulation: Dynamically adjust the ratio of pre- and post-exchange to reduce blood concentration and reduce the risk of dialyzer coagulation.

[0050] 6) Simplify the operation process: automatically calculate and adjust the replacement fluid volume and distribution ratio to reduce the workload of operators.

[0051] 7) Cost savings: Reduce the risk of dialyzer clotting, extend the service life of the dialyzer, and reduce vascular access complications.

[0052] The above-described embodiments merely represent specific implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of protection of the present application. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the technical concept of the present application, and all such variations and improvements fall within the scope of protection of the present application.

Claims

1. A method for dynamically adjusting the flow rate of a replacement fluid, characterized in that: The method is as follows: determining an initial front replacement fluid flow rate and an initial back replacement fluid flow rate, monitoring transmembrane pressure in real time, and using a feedback control algorithm to calculate an adaptive adjustment step length of the replacement fluid flow rate based on the degree to which the transmembrane pressure deviates from a target range, and dynamically adjusting the front replacement fluid flow rate and the back replacement fluid flow rate according to the adaptive adjustment step length.

2. A method for dynamically adjusting the flow rate of replacement fluid according to claim 1, characterized in that: The control system uses a piecewise linear function to calculate the adaptive adjustment step size : ， in, Indicates the dynamic adjustment step of the replacement fluid flow rate, Indicates the minimum adjustment step, ranging from 3ml / min to 7ml / min; Indicates the maximum adjustment step, ranging from 18ml / min to 22ml / min; Indicates the transmembrane pressure deviation, Indicates the upper limit of transmembrane pressure deviation, ranging from 40mmH to 60mmH.

3. The method for dynamically adjusting the displacement fluid flow rate according to claim 1, characterized in that: The feedback control algorithm includes an initial pre-substitution fluid flow algorithm, an initial post-substitution fluid flow algorithm, and a transmembrane pressure dynamic feedback algorithm; the transmembrane pressure dynamic feedback algorithm includes the following steps: Set the total displacement conservation constraint so that the total displacement remains constant during any adjustment: ， in, is the total replacement fluid flow, is the flow rate of the replacement fluid before, is the post-displacement fluid flow rate; Set TMP feedback adjustment rules: When the TMP is increased, the blood concentration can be increased by reducing the flow rate of the replacement fluid before and increasing the flow rate of the replacement fluid after: ， ， , to prevent the front replacement fluid flow from being negative; in, represents the transmembrane pressure, Indicates the lower threshold of transmembrane pressure, Indicates the dynamic adjustment step of the replacement fluid flow rate, Indicates the replacement fluid flow adjustment step, Adaptively adjust the step size according to the degree to which TMP deviates from the threshold ; when When the TMP is reduced, the blood concentration can be reduced by reducing the post-replacement fluid flow and increasing the pre-replacement fluid flow: ， ， , to prevent the post-displacement fluid flow from being negative; in, Indicates the upper threshold of transmembrane pressure; when When the flow rate of the replacement fluid is maintained unchanged.

4. The method for dynamically adjusting the displacement fluid flow rate according to claim 3, characterized in that: The initial pre-substitution fluid flow rate algorithm and the initial post-substitution fluid flow rate algorithm comprise the following steps: Calculate plasma water flow rate : , in, is the effective blood flow, is the hematocrit; The ratio of water to plasma components ranges from 90% to 95%; Calculate total replacement fluid flow : , in, represents the displacement coefficient, ranging from 0.7 to 1.0; Calculation of replacement fluid flow rate : , in, is the dehydration rate; Set a value for the filtration fraction, ranging from 0.3 to 0.5; is the filtration fraction, and ; Calculate the replacement fluid flow rate : .

5. The method for dynamically adjusting the displacement fluid flow rate according to claim 1, characterized in that: The control system collects TMP data in real time and executes the feedback control algorithm according to a preset feedback adjustment cycle of 5 minutes to 10 minutes.

6. The method for dynamically adjusting the displacement fluid flow rate according to claim 3, characterized in that: The control system is equipped with a safety boundary and an alarm module. or , the displacement flow rate will be forced to be set to 0 and an alarm will be issued.

7. A system for dynamically adjusting the flow rate of replacement fluid, characterized in that: include: Blood circulation module: including blood pump, arterial bottle, venous bottle, blood pipeline and dialyzer; Replacement fluid module: including replacement fluid preparation unit, front replacement fluid pump, rear replacement fluid pump and related pipelines; Dialysis fluid module: includes dialysate preparation unit, ultrafiltration pump and related pipelines; Monitoring system: including pressure sensor, temperature sensor, and hematocrit sensor; Control system: includes main control unit, feedback control algorithm module, human-computer interaction interface, safety boundary and alarm module.

8. The system for dynamically adjusting the flow rate of replacement fluid according to claim 7, characterized in that: The feedback control algorithm module includes an initial front replacement fluid flow algorithm, an initial rear replacement fluid flow algorithm and a transmembrane pressure dynamic feedback algorithm; the initial front replacement fluid flow algorithm and the initial rear replacement fluid flow algorithm determine the initial front replacement fluid flow and the initial rear replacement fluid flow according to the hematocrit, the effective blood flow and the dehydration rate; the transmembrane pressure dynamic feedback algorithm dynamically adjusts the front replacement fluid flow and the rear replacement fluid flow according to the transmembrane pressure in real time, not only adjusting according to the TMP deviation direction, but also dynamically calculating the step length required for each adjustment of the replacement fluid flow according to the degree of deviation. .

9. The system for dynamically adjusting the flow rate of replacement fluid according to claim 8, characterized in that: The transmembrane pressure dynamic feedback algorithm comprises the following steps: Set the total displacement conservation constraint so that the total displacement remains constant during any adjustment: ， in, is the total replacement fluid flow, is the flow rate of the replacement fluid before, is the post-displacement fluid flow rate; Set TMP feedback adjustment rules: When the TMP is increased, the blood concentration is increased by reducing the flow rate of the replacement fluid before and increasing the flow rate of the replacement fluid after: ， ， , to prevent the front replacement fluid flow from being negative; in, represents the transmembrane pressure, Indicates the lower threshold of transmembrane pressure, Indicates the dynamic adjustment step of the replacement fluid flow rate, Indicates the replacement fluid flow adjustment step, Adaptively adjust the step size according to the degree to which TMP deviates from the threshold ; when When the TMP is reduced, the blood concentration can be reduced by reducing the post-replacement fluid flow and increasing the pre-replacement fluid flow: ， ， , to prevent the post-displacement fluid flow from being negative; in, Indicates the upper threshold of transmembrane pressure; when When , the current replacement fluid flow rate remains unchanged; According to the degree of TMP deviation from the threshold, a piecewise linear function is used to adaptively adjust the step size. : ， in, Indicates the dynamic adjustment step of the replacement fluid flow rate, Indicates the minimum adjustment step, ranging from 3ml / min to 7ml / min; Indicates the maximum adjustment step, ranging from 18ml / min to 22ml / min; Indicates the transmembrane pressure deviation, Indicates the upper limit of transmembrane pressure deviation, ranging from 40mmH to 60mmH.

10. A hemodiafiltration device, characterized in that: A system for dynamically adjusting the replacement fluid flow rate according to any one of claims 7 to 8 is used to implement a method for dynamically adjusting the replacement fluid flow rate according to any one of claims 1 to 6.

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