Pressure control method and device for maintaining stable mechanical perfusion of organ

Abstract

The invention discloses a pressure control method for maintaining stable mechanical perfusion of an organ and a device using the method, perfusate is conveyed to the organ through a pump, the perfusion pressure of a perfusion pipeline is increased from zero to target pressure, the target pressure is further divided into a plurality of stages of target pressure, and the target pressure is controlled to be stable. And each stage reaches the stage target pressure according to a specific rising curve. By means of the pressure control method, safe and stable mechanical perfusion of organs can be maintained, and perfusion mechanical damage to the kidney caused by overpressure perfusion can be avoided.

Description

Technical Field

[0001] The invention belongs to the field of biomedical instruments, and in particular relates to a low-temperature mechanical perfusion pressure control method for organ transplantation. Background Art

[0002] Organ transplantation refers to the transfer of viable ex vivo organs to the patient's body through surgery. During organ storage, the temperature must be controlled at a low temperature environment of 2-8°C. The traditional organ preservation method is static cold preservation. The longer the static cold preservation time, the higher the incidence of delayed recovery of graft function after surgery. In addition, static cold preservation makes it difficult to objectively evaluate ex vivo organs. Compared with static cold preservation, low-temperature mechanical perfusion of ex vivo organs can significantly reduce the incidence of delayed recovery of graft function, which is beneficial to improving the long-term survival rate of transplanted organs. At the same time, mechanical perfusion parameters can assist in evaluating the quality of transplanted organs, which is conducive to the full utilization of ex vivo organs. The organ perfusion transport box is a device for ex vivo organ transportation, preservation and low-temperature mechanical perfusion for transplantation. Organ perfusion transport can prolong the storage time of ex vivo organs, evaluate the quality of ex vivo organs, and reduce the incidence of postoperative DGF (delayed recovery of transplanted organ function). It is now widely used. For example, the LifePort kidney perfusion transport box launched by LSI in the United States is the most widely used low-temperature mechanical perfusion product in clinical practice. It has obtained registration certificates and is sold in the three major markets of China, the United States and Europe.

[0003] For renal mechanical perfusion equipment, its perfusion safety control is mainly reflected in two aspects: temperature control and mechanical damage control. Temperature control is relatively simple, especially for low-temperature mechanical perfusion. The selection of suitable insulation materials and internal refrigerants can achieve a low-temperature environment for a long time. Mechanical damage control is more complicated. Usually, a constant low pressure far lower than the normal systolic pressure of the human body is used for perfusion. Constant pressure perfusion is equivalent to setting a maximum limit for the perfusion pressure of the kidney to protect the safety of the organ. Different kidneys will produce different perfusion flows using the same constant pressure. If the renal vascular resistance is small, the flow rate is large, and if the renal vascular resistance is large, the flow rate is small. It is not easy to maintain a stable pressure with low flow and high resistance perfusion, and the control requirements for the perfusion pump are high. If the control is not fine enough, overpressure is likely to occur, and overpressure perfusion may cause perfusion mechanical damage to the kidney. In order to avoid overpressure perfusion, an allowable range is usually set. If the pressure exceeds the allowable range, the perfusion is stopped to avoid perfusion damage.

[0004] In organ transplantation, there are many young and marginal kidney donors. These kidneys may have the problem of too high initial perfusion resistance. The overpressure caused by high resistance can easily trigger the cessation of perfusion. After the perfusion stops, the kidney is in a static refrigerated state. Usually, the perfusion process is unattended. In this case, the use of mechanical perfusion can neither achieve clinical results nor cause economic losses. Therefore, a safe and stable pressure control method is particularly important in kidney perfusion, and the existing organ perfusion transport box still has room for improvement in terms of ease of use, perfusion safety, and data accuracy. Summary of the invention

[0005] The present invention provides a pressure control method for maintaining safe and stable mechanical perfusion of an organ, which can also be called a perfusion pump control method for maintaining safe constant pressure perfusion of an organ.

[0006] In the pressure control method of the present invention, the perfusion fluid is delivered to the organ by a peristaltic pump, so that the perfusion pressure of the perfusion pipeline is increased from zero to the target pressure, and the pressure rise curve is Y=-PX 2 / A 2 +2PX / A, where P is the target pressure, A is the total time to reach the preset target pressure, X is the time, and Y is the stage target pressure during the pressure rise process.

[0007] When the constant pressure perfusion mode is used, in order to stabilize the pressure, the peristaltic pump needs to stop and rotate within a fixed single cycle time T. The rotation time T1 + the stop time T2 = the single cycle time T. The pressure rises during the peristaltic pump rotation time T1, and the pressure drops during the peristaltic pump stop time T2. The pressure is stabilized by rotating to increase the pressure and stopping to reduce the pressure. The pressure rise process is divided into A / T stages, A / T = 1, 2, ..., n, n is an integer, and the rotation time of each stage is expressed as T 1-1 , T 1-2 ,…,T 1-n , the stop time of each stage is expressed as T 2-1 , T 2-2 ,…,T 2-n , the pressure rise curve at each stage is Y1=-PT 2 / A 2 +2PT / A, Y2=-P(2T) 2 / A 2 +2P(2T) / A,…,Y n =-P(nT) 2 / A 2 +2P(nT) / A,Y1,Y2,…,Y n is the stage target pressure. In the first stage, the starting pressure is 0, and zero pressure calibration can be performed first. The output control amount is calculated using the PID algorithm through the deviation Y1, and then converted into a PWM waveform to control the peristaltic pump to rotate for a certain time T.1-1 The pump rotates at a constant speed to reach the stage target pressure Y1, records the current actual pressure value P1 and stops the peristaltic pump; in the second stage, P1 is used as the starting pressure and the output of PWM is calculated by PID through the deviation Y2-P1 to control the peristaltic pump to rotate for a certain time T 1-2 The internal uniform speed rotation reaches the stage target pressure Y2, records the current actual pressure value P2 and stops the peristaltic pump, and uses P2 as the starting pressure of the next stage, and so on, until the actual pressure rises to the target pressure P.

[0008] Furthermore, in order to avoid pressure fluctuations caused by high resistance, set the resistance limit R0, R0 = pressure / flow, R0 is 1.5-2.0. During the pressure rise process, if the resistance reaches R0 before the target pressure P is reached, the pump is controlled to stop running, and A in the pressure rise curve is adjusted to 2A. According to Y = -PX 2 / (4A 2 )+PX / A for perfusion, and reduce the occurrence of high resistance by extending the time of pressure rise; if the limiting resistance R0 is still triggered after the extension time, the control pump stops running, and selects one of the first 1-5 stage target pressures that trigger the limiting resistance R0 as the temporary target pressure and resumes perfusion; when the resistance drops to mR0, m<1, resume with Y=-PX 2 / (4A 2 )+PX / A increases the pressure until the target pressure P is reached. The resistance is obtained by the average pressure / real-time flow.

[0009] Furthermore, a resistance limit R0 is set. After the perfusion pressure reaches P, if the resistance reaches R0, the peristaltic pump is controlled to stop running for 2-10 seconds and then the perfusion is resumed.

[0010] Furthermore, after the pressure reaches the target pressure P, the peristaltic pump is controlled to stop running. When the pressure loss is detected to be ≥1 mmHg, the output of PWM calculated by PID is used to control the peristaltic pump to reach P-K+1 within the next single cycle rotation time through deviation 1, where K is the pressure loss value. The actual pressure tested at the end of the rotation time is taken as input, and the output of PWM calculated by PID is continued to be used to control the peristaltic pump to increase the pressure smoothly through deviation 1. If the actual pressure + 1 tested at the end of the rotation time is greater than the target pressure P, the output of PWM calculated by PID is used to control the peristaltic pump to increase the pressure smoothly to the target pressure P through the deviation (P-actual pressure tested at the end of the rotation time).

[0011] Furthermore, a limiting pressure hP is set, where h is 1.1-1.3. When the perfusion pressure exceeds the target pressure P value but is lower than hP, the high pressure is corrected by pressure loss. If the perfusion pressure reaches or exceeds hP, the control is switched to exhaust mode until the pressure in the perfusion line drops below sP, where s is 0.3-0.5. The control is then switched back to perfusion mode and the pressure continues to be increased to the target pressure P according to the pressure loss.

[0012] Furthermore, in order to control the stability of pressure, in the pressure rising stage or the pressure stable stage, when the stage target pressure or the target pressure P is reached, the duty cycle output of the peristaltic pump does not reach 100%. The system outputs a PWM waveform through the PID algorithm to control the duty cycle of the peristaltic pump to achieve different target pressures, T1 = T2, that is, the rotation time in each single cycle time T is equal to the stop time. When the duty cycle output of the peristaltic pump reaches 100% when the stage target pressure or the target pressure P is reached, the peristaltic pump output becomes a fixed value of 100%, T1>T2, and the system increases the T1 time and the rotation time to achieve different target pressures.

[0013] When the duty cycle output of the peristaltic pump reaches 100% and the rotation time reaches T, if the real-time pressure continues to rise and approaches P, it may exceed P or even hP in the next single cycle. At this time, the perfusion will be stopped because the pressure exceeds the limit value. To avoid this situation, the single-cycle rotation time limit can be set, and T2>0, which can be specifically set to T2=T*f, where f ranges from 0.1-0.2.

[0014] Furthermore, after the peristaltic pump rotates for T / 2 time in a single cycle, the actual pressure is fed back every 10ms and compared with the stage target pressure. If the stage target pressure is not reached, the peristaltic pump continues to rotate. If the stage target pressure or the target pressure P is reached, the peristaltic pump stops rotating.

[0015] The present invention also provides an organ low-temperature mechanical perfusion device, which adopts the above-mentioned pressure control method.

[0016] The pressure control method of the present invention has the advantages of stable pressure rise, timely detection of overpressure, over-resistance and the like and taking countermeasures, thereby avoiding mechanical perfusion damage to the kidney caused by overpressure perfusion. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the principle of the perfusion device according to an embodiment of the present invention;

[0018] Figure 2 is a graph showing theoretical changes in pressure over time according to an embodiment of the present invention;

[0019] Figure 3is a curve diagram showing actual changes in pressure over time in an embodiment of the present invention;

[0020] In the figure: 1 is a low temperature unit, 2 is an organ box, 3 is an organ, 4 is a pump, 5 is a filter, 6 is a flow sensor, 7 and 10 are bubble sensors, 8 and 11 are solenoid valves, 9 is a bubble elimination unit, 12 is a pressure sensor, 110 is an exhaust circuit, and 120 is a perfusion circuit. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. However, the embodiments described below are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] Figure 1 An embodiment of an isolated organ low-temperature mechanical perfusion preservation device is shown. The isolated organ low-temperature mechanical perfusion preservation device includes a low-temperature unit 1, an organ box 2, an organ 3, a pump 4, a filter 5, a flow sensor 6, bubble sensors 7 and 10, solenoid valves 8 and 11, a bubble elimination unit 9, a pressure sensor 12, and a control unit (not shown). The organ box 2, the pump 4, the filter 5, the flow sensor 6, the bubble sensor 7, the bubble elimination unit 9 and the solenoid valve 8 are connected by pipes to form an exhaust circuit 110. The organ box 2, the pump 4, the filter 5, the flow sensor 6, the bubble sensor 7, the bubble elimination unit 9, the bubble sensor 10, the solenoid valve 11, the pressure sensor 12 and the organ 3 are connected by pipes to form a perfusion circuit 120. The entire device is heat-insulated from the external environment.

[0023] The organ 3 may be an isolated organ of a human or animal, and the isolated organ used in this embodiment is a kidney. The organ box is configured to allow a perfusion bath to be formed around the organ. The organ box is configured to provide uninterrupted sterile conditions during transportation, recovery, analysis, and storage while maintaining thermal conductivity with the cryogenic unit.

[0024] The organ box 2 is arranged in the low temperature unit 1. The low temperature unit is usually an ice box with a concave portion. The ice box can contain cooling media such as ice, ice water, saline, etc., and any other suitable cooling media, such as polymer phase change gel material, can also be used. In use, the organ is arranged in the bracket, the bracket is arranged in the organ box, and the organ box is arranged in the ice box. In this way, the ice box surrounds the outer periphery of the organ box, so that the temperature of the organ box is maintained in a low temperature environment of 0-8°C. The ice box provides cooling for the organ without directly contacting the organ.

[0025] The filter 5 is used to filter particles in the liquid path to prevent particles from entering and blocking the flow path of the device. The particles can be, for example, fat particles or blood coagulation produced by an isolated organ. The filter can be a single filter or a combination of multiple filters with different pore sizes. Here, a 20 μm filter purchased from outside is used.

[0026] The pump 4 may be any pump suitable for use in conjunction with the perfusion of an organ. Examples of suitable pumps may include a manually operated pump, a centrifugal pump, and a peristaltic pump, where a 75 rpm DC motor peristaltic pump purchased from an external source is used.

[0027] The flow sensor 6 is used to detect the flow rate of the perfusion liquid flowing through the pipeline, and the flow sensor can be an ultrasonic flow sensor. The flow sensor is arranged in the pipeline, and by comparing the detection data of the flow sensor with the flow data of the pump itself, it can be timely determined whether the pump fails and whether the perfusion system leaks, which can improve the problem of inaccurate flow display caused by deformation, aging or failure of the pump components when relying only on the flow data of the pump itself, thereby improving the accuracy of the perfusion data.

[0028] The bubble sensors 7 and 10 are used to detect whether there are bubbles in the perfusion fluid flowing through. Ultrasonic bubble sensors may be used. The ultrasonic bubble sensors do not contact the perfusion fluid, so they do not need to be cleaned and are easy to replace.

[0029] The bubble removal unit 9 preferably separates air bubbles that may be entrained in the perfusate flow, preventing these bubbles from continuing downstream and entering the isolated organ.

[0030] The pressure sensor 12 detects the real-time pressure of the fluid circuit and provides overpressure monitoring. In the case where the pressure of the perfusate flowing through the pipeline exceeds a predetermined threshold, the device can automatically stop and / or reduce the flow provided by the pump to prevent damage to the organ.

[0031] 1. Exhaust mode

[0032] Before perfusion, the pipeline is exhausted, the solenoid valve 11 closes the pipeline, the solenoid valve 8 is opened, and the organ box 2, the pump 4, the filter 5, the flow sensor 6, the bubble sensor 7, the bubble elimination unit 9 and the solenoid valve 8 form an exhaust circuit 110. The pump 4 rotates at a fixed duty cycle to pump out the perfusion liquid in the organ box 2, passes through the filter 5, the flow sensor 6, the bubble sensor 7 to the bubble elimination unit 9, and the liquid and the bubbles in the pipeline return to the organ box 2 through the solenoid valve 8 to complete the exhaust.

[0033] 2. Perfusion Mode

[0034] In the perfusion mode, the solenoid valve 8 is closed, the solenoid valve 11 is opened, and the organ box 2, the pump 4, the filter 5, the flow sensor 6, the bubble sensor 7, the bubble elimination unit 9, the bubble sensor 10, the solenoid valve 11, the pressure sensor 12 and the organ 3 form a perfusion circuit 120. The pump 4 rotates at a fixed duty cycle to pump out the perfusion solution in the organ box 2, and returns to the organ box 2 through the filter 5, the flow sensor 6, the bubble sensor 7, the bubble elimination unit 9, the bubble sensor 10, the solenoid valve 11, and the pressure sensor 12. The renal artery is connected to the perfusion line using a connecting cannula to perform kidney perfusion.

[0035] Among them, when the bubble sensor 6 or 10 on the perfusion circuit detects the presence of bubbles in the perfusion fluid flowing through, the controller controls the solenoid valve 11 to close and the solenoid valve 8 to open, and the perfusion fluid is discharged through the exhaust circuit until the bubble sensor no longer detects bubbles. The controller controls the solenoid valve 11 to open and the solenoid valve 8 to close, and the perfusion mode is restarted.

[0036] The flow sensor 6 on the perfusion loop monitors the flow rate B1 of the perfusion liquid flowing through, and the pump 4 itself can monitor the flow rate B2 pumped into the pipeline. When the flow rate B1 is less than a certain value of B2, it is inferred that there is leakage in the middle section of the pipeline or the pump is abnormal. The controller controls the perfusion mode to stop and the device issues a warning.

[0037] Specifically, after the perfusion process begins, the perfusion fluid is delivered to the organ by a pump. Figure 2 , so that the perfusion pressure of the perfusion pipeline increases from zero to the target pressure, and the pressure rise curve is Y = -PX 2 / A 2 +2PX / A, where P is the target pressure, set to 45mmHg, A is the total time to rise to the target pressure, set to 60s, X is the time, and Y is the target pressure during the pressure rise process. The pressure rise curve formula is Y=-45X 2 / 3600+2*45X / 60.

[0038] refer to Figure 3 In order to refine the pressure control, the pressure rise process is divided into A / T stages, T is the single cycle of the pump operation, which is 2s. Therefore, the pressure rise process is divided into 30 stages, and the target pressure of each stage is Y1=2.95mmHg, Y2=5.8mmHg, ..., Y 29 =44.95mmHg, Y 30 =45mmHg. In a single cycle, T includes the rotation time and the stop time. The pipeline pressure rises during the rotation time and decreases during the stop time.

[0039] In the first stage, the starting pressure is 0. Zero pressure calibration is performed first. The output control quantity is calculated using the PID algorithm through the deviation Y1, and then converted into a PWM waveform to control the pump to rotate at a constant speed within 1 second to reach the stage target pressure Y1. The actual pressure value P1 (3.12 mmHg) at this time is recorded by the pressure sensor on the pipeline. After the pump stops rotating for 1 second, it enters the next stage.

[0040] In the second stage, the PID is used to calculate the PWM output through the deviation Y2-P1 to control the pump to rotate at a constant speed within 1 second to reach the stage target pressure Y2, and the actual pressure value P2 (5.70 mmHg) at this time is recorded. After the pump stops rotating for 1 second, it enters the next stage, and so on, until the pressure rises to the target pressure P.

[0041] Set the resistance limit R0, R0 = pressure / flow, R0 = 1.8. During the pressure rise process, calculate the resistance through the pipeline pressure detected by the pressure sensor and the pipeline flow detected by the flow sensor. If the pipeline pressure has not reached the target pressure P and the resistance has reached R0, the control pump will stop running and adjust A in the pressure rise curve to 2A. According to Y = -PX 2 / (4A 2 )+PX / A for perfusion, and the occurrence of high resistance is reduced by extending the time of pressure rise. If the limit resistance R0 is still triggered after the extension time, the control pump stops running, and selects one of the first 1-5 stage target pressures that trigger the limit resistance R0 as the temporary target pressure and resumes perfusion. For example, when the resistance limit is triggered during perfusion at stage Y7, Y5 can be selected as the temporary target pressure and perfusion can be resumed. When the resistance drops to 0.8*R0, it is resumed with Y=-PX 2 / (4A 2 )+PX / A increases the pressure until it reaches the target pressure P. After the perfusion pressure reaches the target pressure P, if the resistance reaches R0, the control pump stops running for 2-10 seconds and then resumes perfusion.

[0042] After the pressure reaches the target pressure P, the pump is controlled to stop running. When the pressure loss is detected to be ≥1mmHg, the PID output is used to calculate the PWM control pump through the deviation 1 to reach P-K+1 within the next single cycle rotation time, where K is the pressure loss value. The actual pressure tested at the end of the rotation time is used as input, and the PID output is used to calculate the PWM control pump to gradually increase the pressure. If the actual pressure + 1 tested at the end of the rotation time is greater than the target pressure P, the PID output is used to calculate the PWM control pump to gradually increase the pressure to the target pressure P through the deviation (P-actual pressure tested at the end of the rotation time).

[0043] Set the limit pressure hP, h is 1.2, when the perfusion pressure exceeds the target pressure P value but is lower than hP, the high pressure is corrected by pressure loss. If the perfusion pressure reaches or exceeds hP, the control switches to exhaust mode until the pressure in the perfusion line drops below sP, s is 0.4, the control switches back to perfusion mode and continues to increase the pressure to the target pressure P according to the pressure loss.

[0044] In this embodiment, the pressure is increased from 0 to 45 mmHg in 30 single cycles. The pressure in the previous stage is relatively low. In order to control the stability of the pressure, the first strategy is to maintain T1=T2, which is T1=T2=1s in this embodiment. The system outputs PWM waveforms through the PID algorithm to control the duty cycle of the pump to reach Y1, Y2, ...Y n , the duty cycle range is 0-100% (the size of the duty cycle is the size of the rotation speed per unit time, and the upper limit of the pump speed is the duty cycle = 100%). The smaller the stage target pressure and the greater the resistance, the smaller the output duty cycle of the pump. Similarly, the greater the stage target pressure and the smaller the resistance, the greater the duty cycle the pump needs to output. First, maintain the perfusion strategy of T1 = T2. Since the rotation time and the stop time are equal, the perfusion will be more stable. During the rising process, if the perfusion resistance is very small, the pump needs to increase the duty cycle. If it has increased to 100% and has not reached the target pressure, it is necessary to increase the T1 time, that is, increase the single-cycle rotation time and reduce the single-cycle stop time. The system feeds back the real-time pressure every fixed time (such as 10ms). If the target pressure is not reached, the pump continues to rotate. If the target pressure has been reached, the pump stops rotating and enters the T2 time. Therefore, when the pump output power increases to 100%, T1≥T2. The frequency of T1≥T2 during the perfusion process is related to the pump power and maximum speed (flow rate) selected for the perfusion system. Generally speaking, the greater the maximum speed of the pump, the smaller the probability of T1≥T2. In this embodiment, the flow rate range of the pump is 0-1000ml / min.

[0045] When the pump duty cycle output reaches 100% and the rotation time reaches T, if the real-time pressure continues to rise and approaches P, it may exceed P in the next single cycle, or even exceed hP. At this time, the perfusion will be stopped because the pressure exceeds the limit value. To avoid this situation, a single-cycle rotation time limit can be set, that is, T2>0, which can be specifically set to T2=T*f, where f ranges from 0.1-0.2.

Claims

1. A pressure control method for maintaining stable mechanical perfusion of an organ, characterized in that: The perfusion fluid is delivered to the organ by a pump, so that the perfusion pressure of the perfusion pipeline is increased from zero to the target pressure. The pressure rise curve is Y = -PX 2 / A 2 +2PX / A, where P is the target pressure, A is the total time to reach the preset target pressure, X is the time, and Y is the stage target pressure during the pressure rise process.

2. The pressure control method according to claim 1, characterized in that: The pressure rise process is divided into A / T stages, T is a single cycle of the pump, A / T = 1, 2, ..., n, n is an integer, and the time of a single cycle includes the rotation time and the stop time. According to the pressure rise curve, the target pressure of each stage is Y1 = -PT 2 / A 2 +2PT / A, Y2=-P(2T) 2 / A 2 +2P(2T) / A,…,Y n =-P(nT) 2 / A 2 +2P(nT) / A,Y1,Y2,…,Y n Pressure for phased goals; In the first stage, the starting pressure is 0, and the pump is controlled to rotate at a constant speed and stop after reaching the stage target pressure Y1, and the current actual pressure value P1 is recorded and used as the starting pressure of the next stage; in the second stage, the pump is controlled to rotate at a constant speed and stop after reaching the stage target pressure Y2, and the current actual pressure value P2 is recorded and used as the starting pressure of the next stage, and so on, until the actual pressure rises to the target pressure P.

3. The pressure control method according to claim 2, characterized in that: Set the resistance limit R0, R0 is 1.5-2.

0. During the pressure rise process, if the resistance reaches R0 before the target pressure P is reached, the pump will be controlled to stop running, and A in the pressure rise curve will be adjusted to 2A. According to Y=-PX 2 / (4A 2 )+PX / A for perfusion, and reduce the occurrence of high resistance by extending the time of pressure rise; if the limiting resistance R0 is still triggered after the extension time, the control pump stops running, and selects one of the first 1-5 stage target pressures that trigger the limiting resistance R0 as the temporary target pressure and resumes perfusion; when the resistance drops to mR0, m<1, resume with Y=-PX 2 / (4A 2 )+PX / A increases the pressure until the target pressure P is reached.

4. The pressure control method according to claim 2, characterized in that: Set the resistance limit R0. After the perfusion pressure reaches the target pressure P, if the resistance reaches R0, the control pump stops running for 2-10 seconds and then resumes perfusion.

5. The pressure control method according to claim 2, characterized in that: After the pressure reaches the target pressure P, the pump is controlled to stop running. When the pressure loss is detected to be ≥1mmHg, the pump is controlled to reach P-K+1 within the next single cycle rotation time through deviation 1, where K is the pressure loss value. The actual pressure tested at the end of the rotation time is used as input, and the pump is continued to be controlled to increase the pressure smoothly through deviation 1. If the actual pressure +1 tested at the end of the rotation time is greater than the target pressure P, the pump is controlled to increase the pressure smoothly to the target pressure P through the deviation value between the target pressure P and the actual pressure tested at the end of the rotation time.

6. The pressure control method according to claim 2, characterized in that: Set the limiting pressure hP, where h is 1.1-1.

3. When the perfusion pressure exceeds the target pressure P value but is lower than hP, correct the high pressure by pressure loss. If the perfusion pressure reaches or exceeds hP, the control switches to exhaust mode until the pressure in the perfusion line drops below sP, where s is 0.3-0.

5. The control switches back to perfusion mode and continues to increase the pressure to the target pressure P according to the pressure loss.

7. The pressure control method according to claim 2, characterized in that: The pump rotation time is greater than or equal to T / 2.

8. The pressure control method according to claim 2, characterized in that: After the pump rotates for T / 2 time in a single cycle, the actual pressure is fed back every 10ms and compared with the stage target pressure. If the stage target pressure is not reached, the pump continues to rotate. If the stage target pressure or target pressure P is reached, the pump stops rotating.

9. The pressure control method according to any one of claims 1 to 7, characterized in that: The pump is a peristaltic pump, which calculates the output control quantity through a PID algorithm and then converts it into PWM waveform control.

10. An organ low-temperature mechanical perfusion device, which adopts the pressure control method according to any one of claims 1 to 7.

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