Method and system for judging air tightness abnormity of air path pipe of percutaneous left ventricular assist device

Abstract

The invention belongs to the field of heart auxiliary equipment detection, and discloses a method and system for judging the air tightness abnormity of a percutaneous left ventricle auxiliary device air path pipe. The method comprises the following steps: carrying out periodic inflation and inhalation control on the percutaneous left ventricular assist device; collecting pressure P in an air channel pipe of the percutaneous left ventricle auxiliary device in real time; and analyzing the pressure PN of the negative pressure stage of the air path pipe caused by air suction control to determine whether the air tightness of the air path pipe is abnormal or not. According to the method and the system, the pressure in the negative pressure stage is used as a basis for analyzing whether the gas path pipe has abnormal gas tightness such as falling or leakage, and compared with a traditional mode of comparing the air pressure in the gas charging stage with a threshold value, the interference of other factors such as gas charging strength and control rate is eliminated, so that judgment is easier to implement, and the detection accuracy is improved. And the accuracy of the result is improved, and the false alarm rate and the missing report rate are reduced.

Description

Technical Field

[0001] The present invention relates to the field of cardiac assist device detection, and in particular to a method and system for determining abnormal air tightness of an airway tube of a percutaneous left ventricular assist device. Background Art

[0002] With the development of medical technology, the treatment technology of cardiovascular diseases has made significant progress. Mechanical assist devices play a vital role in the treatment of cardiogenic shock. Physical and chemical means regulate hemodynamic changes, ensure blood reperfusion while allowing the heart to get enough rest and help restore some functions. They can be used as a bridge therapy or transitional therapy to reverse cardiogenic shock and gain time and opportunities for other clinical treatments. Mechanical assist devices are mainly divided into four categories: intra-aortic balloon pump (IABP), percutaneous left ventricular assist device (PVAD), extracorporeal membrane pulmonary circulation and total artificial heart. Among them, IABP is a tool with a higher usage rate among mechanical assist devices. IABP enters the aorta through femoral artery puncture, and the tip is located at the left subclavian artery. During the diastole of the heart, the balloon is inflated to increase diastolic pressure and improve blood perfusion of the coronary arteries, brain, kidneys and mesentery. During the systole of the heart, the balloon is deflated, reducing the left ventricular afterload and promoting the smooth outflow of left ventricular blood. The overall effect is to relieve left ventricular wall pressure and reduce heart work. Active suction of the left ventricle directly decompresses the heart, reducing preload, while generating counter-pulsation blood flow in the ascending aorta, increasing mean arterial pressure. PVAD is significantly superior to traditional IABP in improving hemodynamic metabolic parameters and is the main development direction of cardiac device treatment in the future.

[0003] In some technologies currently under development, an access port for a PVAD catheter is provided on the air circuit of the IABP to realize a multifunctional IABP design. The balloon used in the IABP is usually thinner. In order to prevent the balloon from being blown up or ruptured, a safety disk is usually provided in the air circuit of the aortic balloon pump. The balloon is directly driven after the pressure is transmitted through the safety disk, and the pressure loss is small. Limited by the volume of the safety disk, the pressure value used by the aortic balloon pump to drive the balloon is relatively small. When the PVAD catheter is used for left ventricular assistance, the aortic balloon pump does not work, and the PVAD catheter uses the air source of the aortic balloon pump for corresponding assistance. When the PVAD catheter is connected to the interface of the aortic balloon pump, since the middle part of the PVAD is usually a thinner liquid tube, the liquid flow pressure loss is large, and the required driving pressure is also relatively large. However, the pressure provided by the aortic balloon pump is limited by the safety disc and balloon, which is significantly lower than the driving pressure required by the PVAD catheter. In addition, part of the pressure is lost to the liquid flow, and only another part of the pressure is used to promote blood flow into the aorta. This makes the blood flow through the PVAD catheter into the aorta per unit time less, and thus the auxiliary effect is poor.

[0004] In order to ensure a higher flow rate, one implementation method is to add an air circuit directly connected to the PVAD catheter on the original IABP air circuit. The pipeline is not equipped with a safety disk, and the valve is fully opened during inflation and deflation. Since the fully open valve is inflated, there is dynamic pressure, which means that even if there is an abnormal air tightness (such as falling off or leaking) in the PVAD air circuit tube, the air pressure will not return to the atmospheric pressure level. Therefore, the method of judging the air circuit tube falling off by the atmospheric pressure level is no longer applicable.

[0005] Therefore, there is an urgent need in the art to study a method and system for determining the abnormal airtightness of the airway tube of a percutaneous left ventricular assist device. Summary of the invention

[0006] In view of the above problems, the present invention provides a method and system for determining abnormal air tightness of an airway tube of a percutaneous left ventricular assist device.

[0007] According to one aspect of the present invention, a method for determining abnormal air tightness of a percutaneous left ventricular assist device airway tube is provided, the method comprising the following steps: Periodically controlling the inflation and inspiration of the percutaneous left ventricular assist device; Real-time collection of the pressure P in the airway tube of the percutaneous left ventricular assist device; The pressure P of the negative pressure stage of the airway tube caused by the suction control N An analysis is performed to determine whether there is any abnormality in the air tightness of the air line tube.

[0008] According to an embodiment of the present invention, determining whether there is an abnormality in the air tightness of the gas circuit tube includes determining whether the gas circuit tube has fallen off and / or whether the gas circuit tube has leaked.

[0009] According to one embodiment of the present invention, determining whether the gas line tube is detached comprises: In a single inflation / inhalation cycle, after switching from the inflation control to the inhalation control and after a first preset period T1, the pressure P in the airway tube is periodically collected. N With pressure threshold P v By comparison, the pressure P in the airway tube during a single filling and suction cycle is N Exceeding the pressure threshold P v The number of times is accumulated, and the accumulated number F1 is compared with the first number threshold F v1 In response to the cumulative number F1 exceeding the first number threshold F v1 It is determined that the airway tube is abnormally detached.

[0010] According to one embodiment of the present invention, the pressure threshold P v It is determined based on a dynamic threshold line, and the dynamic threshold line is obtained based on a model, and the model is a relationship model between the air pressure threshold and time in the negative pressure stage.

[0011] According to one embodiment of the present invention, the dynamic threshold line changes linearly, and the dynamic threshold line can be determined by a first moment t1, a second moment t2, an abnormal pressure threshold P1 corresponding to the first moment t1, and an abnormal pressure threshold P2 corresponding to the second moment, wherein the first moment t1 is the moment after the first preset period T1 has passed after the inflation control is switched to the suction control, and the second moment t2 is the starting moment when the rate of change of the pressure in the air circuit tube becomes less than the set value when there is a falling-off abnormality.

[0012] According to an embodiment of the present invention, the method further comprises determining whether to switch from the charging control to the suction control based on a preset control sequence.

[0013] According to one embodiment of the present invention, determining whether the gas line tube is leaking includes: N consecutive charging and inhalation cycles are grouped together, and M consecutive cycles in a group are selected as a single control stage S. In the control stage S, the inhalation valve connected to the air circuit pipe is closed in the selected time period T2 of the inhalation stage of each charging and inhalation cycle, and the pressure difference ΔP between the pressure P4 at the end time t4 of the selected time period T2 and the pressure P3 at the start time t3 is determined, and the pressure difference ΔP is compared with the set pressure difference threshold ΔP. v When the pressure difference ΔP is greater than the set pressure difference threshold ΔP vWhen the period is taken as the marking period, in response to the number F2 of consecutive marking periods in a single control stage S reaching the second number threshold F v2 And determine that the gas line tube is leaking.

[0014] According to an embodiment of the present invention, the number M of consecutive cycles in the single control stage S is determined based on the following two aspects: (1) reducing the false alarm rate; and (2) ensuring the use effect of the auxiliary device.

[0015] According to an embodiment of the present invention, the value range of N is 8-12, the value range of M is 2-4, and the second number threshold F v2 is 2-3.

[0016] According to one embodiment of the present invention, the end time t4 of the selected time period T2 is the end time of the inhalation phase, and the duration of the selected time period T2 is 50-200 ms.

[0017] According to one embodiment of the present invention, the method further comprises determining the severity of the leakage of the gas line tube, wherein the set pressure difference threshold ΔP v Including the first pressure difference threshold ΔP v1 , the second pressure difference threshold ΔP v2 and the third pressure difference threshold ΔP v3 , in response to the pressure difference ΔP being greater than the first pressure difference threshold ΔP v1 and is less than the second pressure difference threshold ΔP v2 The leakage is determined to be low leakage, in response to the pressure difference ΔP being greater than the second pressure difference threshold ΔP v2 and is less than the third pressure difference threshold ΔP v3 The leakage is determined to be a medium leakage, in response to the pressure difference ΔP being greater than the third pressure difference threshold ΔP v3 The leak is determined to be a high leak.

[0018] According to one embodiment of the present invention, the method further comprises collecting the pressure P in the airway tube of the percutaneous left ventricular assist device after the inflation and inspiration control are operated for a preset number of cycles.

[0019] According to another aspect of the present invention, a system for determining abnormal air tightness of an airway tube of a percutaneous left ventricular assist device is provided, the system comprising: at least one memory for storing a machine-readable program; At least one processor is used to call the machine-readable program to execute the method according to any one of the above embodiments.

[0020] Due to the adoption of the above technical scheme, the method and system for judging the abnormal air-tightness of the airway tube of the percutaneous left ventricular assist device provided by the present invention uses the pressure in the negative pressure stage as the basis for analyzing whether the airway tube has air-tightness abnormalities such as detachment or leakage. Compared with the traditional method of comparing the air pressure in the inflation stage with the threshold, it eliminates the interference of other factors such as inflation intensity and control rate, making the judgment not only easier to implement, but also improving the accuracy of the results and reducing the false alarm and missed alarm rates. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings are used to provide a further understanding of the present disclosure and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present disclosure but do not constitute a limitation of the present disclosure. In the accompanying drawings: Figure 1 The air pressure waveform diagram when the air tube does not fall off under different inflation intensities is shown; Figure 2 The air pressure waveform diagram when the airway tube falls off under different inflation intensities is shown; Figure 3 The overall flow chart of the method for determining abnormal air tightness of the airway tube of a percutaneous left ventricular assist device according to one embodiment of the present invention is shown; Figure 4 A schematic diagram showing a gas line tube fall-off pressure combined with a threshold line according to a specific embodiment is shown; Figure 5 A flow chart showing a method for determining abnormal detachment of a percutaneous left ventricular assist device gas circuit tube according to an embodiment of the present invention; Figure 6 The air pressure waveform diagrams of air line pipe leakage and no leakage are shown; Figure 7 A gas pressure waveform diagram after a special control operation is performed according to a specific embodiment is shown; Figure 8 A flow chart showing a method for determining abnormal leakage of a percutaneous left ventricular assist device gas circuit tube according to an embodiment of the present invention; Fig. 9 An analysis diagram of the air pressure waveform when determining the air leakage judgment threshold is shown. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0023] The terms "including" and "having" and any variations thereof in the specification of the present invention and the above-mentioned drawings are intended to cover non-exclusive inclusions; the terms "first", "second", etc. in the specification of the present invention and the claims or the above-mentioned drawings are used to distinguish different objects rather than to describe a specific order. "Multiple" means two or more, unless otherwise clearly and specifically defined.

[0024] In addition, reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present invention. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0025] The existing aortic counterpulsation system has an external consumable PVAD catheter (also referred to as the airway tube here), which cannot be directly assisted. The airway-related alarms must be turned off for normal auxiliary driving. Therefore, it is currently impossible to detect the detachment of the airway tube, and thus it is impossible to prompt the user when the catheter falls off.

[0026] When an air circuit directly connected to the PVAD catheter is added to the original IABP pipeline, the valve of the air circuit is fully opened during the inflation and deflation time. During the inflation stage, since inflation is ongoing, there is dynamic pressure, which means that even if the PVAD catheter falls off, the air pressure in the catheter will not return to the atmospheric pressure level. Moreover, since the auxiliary device needs to change with the changes in the heart rate of the assisted subject, the inflation and suction time will continue to change in different cycles. Changes in inflation time will also cause differences in the final inflation level. Therefore, the method of judging whether the air circuit inflation pressure is close to the atmospheric pressure level to determine the fall-off is no longer applicable. The following is a detailed explanation combined with two sets of figures.

[0027] Figure 1 The following figure shows the pressure waveforms when the air pipe does not fall off under different inflation intensities. The left figure is the pressure waveform of high-intensity inflation, and the right figure is the pressure waveform of low-intensity inflation. Compared with low-intensity inflation, high-intensity inflation requires longer valve opening time and more airflow inflation. From the waveform analysis, low-intensity inflation has a short valve opening time. When it is closed, the dynamic pressure disappears and the air pressure quickly drops back to near atmospheric pressure. Figure 1 As shown in the right figure, the unit of the vertical axis is mmgh (millimeters of mercury). After falling back, the air pressure is roughly between 100 and 0 mmgh, close to 0 mmgh.

[0028] Figure 2The air pressure waveforms when the air circuit tube falls off under different inflation intensities are shown, of which the left figure is the air pressure waveform when the air circuit tube falls off during high-intensity inflation, and the right figure is the air pressure waveform when the air circuit tube falls off during low-intensity inflation. When the air circuit tube falls off, since the inflation valve is always open, there is always inflation airflow, dynamic pressure exists, and the positive pressure level is always close to atmospheric pressure, but higher than the atmosphere, which is difficult to distinguish from the positive pressure level when the air circuit tube has not fallen off. At the same time, the inflation intensity usually sets multiple gears, and when the air circuit tube falls off at different gears, the judgment logic set is different. Moreover, the positive pressure level is not only affected by the inflation intensity, but also by the control rate, so the traditional method of using a certain pressure level to judge whether the catheter has fallen off is very complicated and difficult to implement, and the false alarm rate and missed alarm rate are high.

[0029] One of the purposes of the present invention is to provide a method for determining the abnormality of air tightness of the airway tube of a percutaneous left ventricular assist device. Figure 3 As shown, the method generally comprises the following steps: Step S1: periodically controlling inflation and inspiration of a percutaneous left ventricular assist device; Step S2: real-time acquisition of the pressure P in the airway tube of the percutaneous left ventricular assist device; Step S3: The pressure P of the negative pressure stage of the airway tube caused by the inhalation control N Perform analysis to determine if there is any abnormality in the air tightness of the air line tube.

[0030] The method for judging the abnormal air tightness of the airway tube of a percutaneous left ventricular assist device provided by the present invention uses the pressure in the negative pressure stage as the basis for analyzing whether the airway tube has abnormal air tightness such as detachment or leakage. Compared with the traditional method of comparing the air pressure in the inflation stage with the threshold, it eliminates the interference of other factors such as inflation intensity and control rate, making the judgment not only easier to implement, but also improving the accuracy of the results and reducing the false alarm and missed alarm rates.

[0031] In step S1, the percutaneous left ventricular assist device is periodically inflated and inhaled. The inflation and inhalation control needs to be adaptively controlled in accordance with the heart rate of the assisted object. The heart rate of the assisted object can be detected by a device that can obtain the heart rate information of the assisted object, and then the time for each inflation operation and inhalation operation is determined according to the heart rate of the assisted object, and the control sequence of the inflation control and the inhalation control is pre-planned in time sequence, and then the periodic inflation and inhalation control is implemented according to the pre-planned control sequence. During inflation, an opening command is sent to the positive pressure valve, and the positive pressure valve opens after receiving the command, and the gas in the gas source flows into the gas circuit tube, and the pressure in the gas circuit tube increases. During inhalation, an opening command is sent to the negative pressure valve, and the negative pressure valve opens after receiving the command, and the gas in the gas circuit tube is sucked away, and the pressure in the gas circuit tube drops to negative pressure.

[0032] In step S2, the pressure P in the airway tube of the percutaneous left ventricular assist device is collected in real time.

[0033] In step S3, the pressure P of the airway tube in the negative pressure stage caused by the air intake control is N An analysis is performed to determine whether there is any abnormality in the air tightness of the gas line tube. For example, when the gas line tube falls off, the negative pressure will slowly rise to the zero point of atmospheric pressure, and if the gas line tube has not fallen off, the negative pressure remains stable. Therefore, it is possible to determine whether the gas line tube has fallen off by analyzing the pressure change trend of the gas line tube in the negative pressure stage. In addition, when the gas line tube leaks, the rate of change of negative pressure can be analyzed with the help of adjusting the suction control (closing the suction valve in the suction stage) to determine whether the gas line tube is leaking. When there is no leakage, the gas line pressure in the negative pressure section changes relatively smoothly; if there is a leakage, the gas line pressure will rise at a faster trend due to the influence of the external air pressure. Therefore, the pressure P in the negative pressure stage can be analyzed. N To determine whether there is any abnormality in the air tightness of the gas line tube.

[0034] In some embodiments of the present invention, determining whether there is an abnormality in the air tightness of the air circuit tube includes determining whether the air circuit tube has fallen off and / or whether the air circuit tube has leaked.

[0035] In some embodiments of the present invention, determining whether the airway tube is detached includes: In a single inflation / inhalation cycle, after switching from inflation control to inhalation control and after a first preset period T1, the pressure P in the airway tube is periodically collected. N With pressure threshold P v For comparison, the pressure P in the airway tube during a single filling and suction cycle is N Exceeding the pressure threshold P v The number of times is accumulated, and the accumulated number F1 is compared with the first number threshold F v1 In response to the cumulative number F1 exceeding the first number threshold F v1 It was determined that the airway tube had fallen off abnormally.

[0036] Optionally, in some embodiments, the pressure threshold P vDetermined based on the dynamic threshold line, the dynamic threshold line is obtained based on a model, and the model is a model of the relationship between the pressure threshold and time in the negative pressure stage. In the inhalation state, the pressure in the airway tube will change with time. Since the performance at different moments is different, different thresholds need to be used for different moments. These thresholds are analyzed to form a model representing the dynamic threshold line, and the dynamic threshold line is used to judge whether the state is detached or not. For example, experimental simulation can be used to determine the pressure in the airway tube at multiple moments after entering the inhalation state when the airway tube is detached, and the threshold corresponding to each moment in the negative pressure stage is determined based on these experimental test data. Then, based on these known threshold data, a model of the relationship between the pressure threshold and time in the negative pressure stage is constructed. Based on the model, a dynamic threshold line can be obtained, and based on the dynamic threshold line, the pressure threshold corresponding to any moment in the time period can be determined. Figure 4 A schematic diagram of the airway tube drop-off pressure combined with the threshold line of a specific embodiment is shown, wherein the thick red line is the dynamic threshold line.

[0037] Optionally, in some embodiments, a starting time is defined for the dynamic threshold line, and the starting time is the moment after the first preset time period T1 has passed after the inflation control is switched to the suction control. In a short period of time after the inflation control is switched to the suction control, due to the high suction intensity, the shedding cannot have a significant impact on the pressure in the air circuit pipe, and it is difficult to distinguish whether the pipeline has fallen off at this stage. After a period of time, the suction intensity decreases, and the impact of the shedding on the pressure in the air circuit pipe becomes significant. The negative pressure in the air circuit pipe that has not fallen off remains stable, and when the air circuit pipe falls off, the negative pressure will slowly rise to near the zero point of atmospheric pressure. Therefore, the pressure in the air circuit pipe after the first preset time period T1 after the inflation control is switched to the suction control can be selected as the analysis data. For example, in some embodiments, the first preset time period T1 can be 80-120ms, and the data can be determined based on actual tests or experience.

[0038] Optionally, in some embodiments, an end time is defined for the dynamic threshold line. When the air tube falls off, the negative pressure will slowly rise to near the zero point of atmospheric pressure. However, when the pressure in the air tube rises to a certain level, its rising speed will significantly decrease, and the change will tend to be gentle, which will interfere with the construction of the model and will no longer be of reference value. Therefore, a change rate threshold can be set for the dynamic threshold line, and the moment when the pressure rise rate begins to fall below the change rate threshold is used as the end time of the dynamic threshold line.

[0039] Optionally, in some embodiments, the first count threshold F v1 is an integer value greater than 1, which can be 2 or 3. The pressure P in the airway tube is repeatedly determined in a single inflation cycle. N Is it greater than the pressure threshold P? v , and the pressure P NExceeding the pressure threshold P multiple times v The situation is judged as an abnormal shedding situation, which can improve the accuracy of the results and reduce the probability of false alarms.

[0040] Optionally, in some embodiments, the dynamic threshold line changes linearly, and the dynamic threshold line can be determined by the first moment t1, the second moment t2, the abnormal pressure threshold P1 corresponding to the first moment t1, and the abnormal pressure threshold P2 corresponding to the second moment, wherein the first moment t1 is the moment after the inflation control is switched to the suction control after the first preset period T1, the second moment t2 is the starting moment when the rate of change of the pressure in the airway tube becomes less than the set value when there is a shedding abnormality, and the abnormal pressure threshold P1 corresponding to the first moment t1 and the abnormal pressure threshold P2 corresponding to the second moment are data determined by experimental simulation. In a specific embodiment, the dynamic threshold line can be expressed by the following formula: P v =P1-(t-t1)*(P1-P2) / (t2-t1) Among them, P v is the pressure threshold corresponding to time t, and time t is between t1 and t2. The pressure threshold P corresponding to time t can be determined based on the above formula v The time t, t1 and t2 are all the time after the timing starts from the switch from the inflation control to the suction control (i.e., t=0 when the switch from the inflation control to the suction control), and are in the suction stage of the same inflation-suction cycle.

[0041] Optionally, in some embodiments, it may also be determined whether to switch from inflation control to suction control based on a preset control sequence.

[0042] Optionally, in some embodiments, the pressure in the airway tube of the percutaneous left ventricular assist device is collected after the inflation and inspiration control have been operated for a preset number of cycles. The accuracy of the analysis result can be improved by waiting for the device to enter a stable working state before collecting data.

[0043] Figure 5 A flow chart of a method for determining abnormal detachment of a percutaneous left ventricular assist device airway tube according to an embodiment of the present invention is shown.

[0044] In step 100, the percutaneous left ventricular assist device is inflated and inhaled according to the heart rate obtained by the physiological detection module, and step 110 is entered after the inflation and inhalation control is performed for a preset number of cycles (three is used as an example in this embodiment).

[0045] In step 110 , the pressure P in the air pipe is collected in real time, and the control timing state of the charging and suction control is obtained, and then the process proceeds to step 120 .

[0046] In step 120 , it is determined whether the state has switched from the charging state to the suction state based on the control sequence state. If yes, the process proceeds to step 130 . Otherwise, the process repeats the step after a time Δt.

[0047] In step 130, when the inflation state is switched to the inhalation state, the timer for recording the duration of the inhalation state in a single inflation-inhalation cycle is reset to zero, and the pressure threshold value P exceeding the pressure in the airway tube in a single inflation-inhalation cycle is recorded. v The counter of the accumulated number of times is reset to zero, and the timer starts timing from this time. Then enter step 140.

[0048] In step 140, after a period of time has passed, the duration T of the inhalation state is determined, and after the determination is completed, the process proceeds to step 150. For example, the duration T of the inhalation state may be determined based on the time recorded by a timer.

[0049] In step 150 , the duration T of the inhalation state is compared with a first preset time period T1 (for example but not limited to 100 ms) to determine whether the duration T is greater than the first preset time period T1 . If yes, proceed to step 160 , otherwise return to step 140 .

[0050] In step 160, it is determined whether the current moment is still in the inhalation state, and the current moment can be compared with the control sequence to determine the current control state. If the current moment is still in the inhalation state, then proceed to step 170, otherwise, return to step 120.

[0051] In step 170, the current gas circuit pressure P and the pressure threshold P corresponding to the current moment are determined. v , compare the current gas path pressure P with the pressure threshold P corresponding to the current moment v Compare and determine whether the gas circuit pressure P is greater than the pressure threshold P v If yes, then go to step S180 , otherwise, go back to step 160 after a time Δt.

[0052] In step 180, the count of the counter is increased by one, and then the count F1 of the counter is compared with the first count threshold F v1 Compare and determine whether the counter count is greater than the first count threshold F v1 (For example, F v1 =3). If yes, then go to step 190, otherwise go back to step 160 after a time Δt.

[0053] In step 190, the control device stops the charging and suction assistance and issues a fall-off alarm.

[0054] The above method can accurately identify the detachment of the trachea.

[0055] There are some differences between leakage and detachment. Since the valve group is fully open during the inflation and inspiration phase, even if there is a leak (regardless of the position), the leaked gas will be immediately replenished because the gas is always supplied, so it is impossible to detect airway leakage. Therefore, the current IABP device connected to the PVAD catheter cannot detect abnormalities in the airway.

[0056] Figure 6 The air pressure waveforms of air circuit tube leakage and no leakage are shown. From the curves of PVAD catheter pressure leakage and no leakage, it can be seen that it is difficult to distinguish leakage or no leakage from the changes in the pressure waveform.

[0057] Therefore, the present invention performs special control on the air intake operation when judging air leakage. During the control time, the air intake valve is closed, and if there is air leakage, the air path pressure will have a slow upward trend; if there is no air leakage, the air path pressure is maintained at a relatively stable pressure level.

[0058] In some embodiments, determining whether the air circuit tube is leaking includes: taking N consecutive charging and inhaling cycles as a group, selecting M consecutive cycles in a group as a single control stage S, closing the inhalation valve connected to the air circuit tube in a selected period T2 of the inhalation phase of each charging and inhalation cycle in the control stage S, determining the pressure difference ΔP between the pressure P4 at the end time t4 of the selected period T2 and the pressure P3 at the start time t3, comparing the pressure difference ΔP with the set pressure difference threshold ΔP v When the pressure difference ΔP is greater than the set pressure difference threshold ΔP v When the number of consecutive occurrences of the marking cycle F2 in the single control stage S reaches the second number threshold F v2 And determine the gas line leak.

[0059] For example, two special control cycles (two consecutive cycles) are performed every ten inflation and inhalation cycles. In these two special control cycles, during the inspiration phase, the inhalation valve is closed 100ms before inflation. If there is a leak, the airway pressure will slowly rise during the 100ms when the inhalation valve is closed. If there is no leak, the airway pressure is maintained at a relatively stable pressure level. In this way, since the inhalation valve is only closed for part of the period in part of the cycle, rather than always closing the inhalation valve in advance, the flow of the PVAD catheter is slightly affected, and leaks can be identified. Figure 7 The figure shows an air pressure waveform diagram after a special control operation is performed in a specific embodiment. By adopting a control strategy of adjusting the air intake valve at intervals, the air pressure waveforms of leakage and no leakage in the negative pressure stage are obviously different.

[0060] In some embodiments, the number M of consecutive cycles in a single control stage S is determined based on the following two aspects: (1) reducing the false alarm rate; (2) ensuring the use effect of the auxiliary device. When the number of special control cycles is small, false alarms may occur due to interference from external factors. When the number of special control cycles is large, the flow rate of the auxiliary device may be affected more, reducing the auxiliary effect. Optionally, in some embodiments, the value range of N is 8-12, the value range of M is 2-4, and the second number threshold F is 1. v2 is 2-3.

[0061] In some embodiments, the end time t4 of the selected time period T2 is the end time of the inhalation stage, that is, the inhalation valve starts to close at a certain time before the end of the inhalation stage and continues until the end of the inhalation stage. The duration of the selected time period T2 can be 50-200ms. The duration of the selected time period T2 needs to comprehensively consider multiple aspects such as the closing reaction time of the inhalation valve, the substantial impact on the air circuit pressure, and the efficiency. When the selected time period T2 is too short, the inhalation valve may not actually be closed or its closing duration is too short, and it has not had a substantial impact on the air circuit pressure, and it is impossible to distinguish and judge whether there is a leak or not. When the selected time period T2 is too long, the energy efficiency is low.

[0062] Optionally, in some embodiments, it may also be determined whether to switch from inflation control to suction control based on a preset control sequence.

[0063] Optionally, in some embodiments, the pressure is collected and the suction valve is closed after the inflation and suction control have been operated for a preset number of cycles. The accuracy of the analysis result can be improved by waiting for the device to enter a stable working state before collecting data and performing identification.

[0064] Figure 8 A flow chart of a method for determining abnormal leakage of an airway tube of a percutaneous left ventricular assist device according to an embodiment of the present invention is shown.

[0065] In step 200, the percutaneous left ventricular assist device is inflated and inhaled according to the heart rate obtained by the physiological detection module, and step 210 is entered after ten cycles of inflated and inhaled control.

[0066] In step 210 , the pressure P in the air pipe is collected in real time, and the control timing state of the charging and suction control is obtained, and then the process proceeds to step 220 .

[0067] In step 220, it is determined whether the current moment has entered the control stage S based on the control sequence state. For example, the current moment can be compared with the set moment of the control sequence to determine. Among them, two consecutive charging and inhaling cycles are set as control cycles in every ten charging and inhaling cycles. The start time of the control stage S is the start time of the first control cycle (i.e., the inflation start time of the first cycle), and the end time of the control stage S is the end time of the second control cycle (i.e., the inhalation end time of the second cycle). If yes, then go to step 230, otherwise repeat this step after the duration Δt.

[0068] In step 230 , after a period of time has passed, the current time is updated, and it is determined whether the state has switched from the inflation state to the inhalation state based on the control timing state. If so, the process proceeds to step 240 , otherwise the process repeats this step after a period of time Δt.

[0069] In step 240 , when the inflation state is switched to the inhalation state, the timer for recording the duration T of the inhalation state in a single inflation-inhalation cycle is reset to zero and starts timing. Then, the process proceeds to step 250 .

[0070] In step 250, after a period of time, it is determined whether the current time has reached the start time for closing the inhalation valve. For example, the duration T of the inhalation state recorded by the timer can be compared with the set start time t for closing the inhalation valve. c Compare to determine, where t c =t f -T2,t f is the time when the next inflation state starts based on the control sequence, and T2 is the set closing time of the air intake valve. c , then go to step S260, otherwise repeat this step after a time of Δt.

[0071] In step 260 , the air intake valve is closed, and the pressure P3 at the closing start time t3 is recorded. Then, the process proceeds to step 270 .

[0072] In step 270, after a period of time, it is determined whether the current moment is switched to the inflation state, and the current moment can be compared with the control sequence to determine the current control state. If yes, then proceed to step 280, otherwise, repeat this step after a duration of Δt.

[0073] In step 280, the air circuit pressure P4 at the time t4 when the inhalation state is switched to the inflation state and the pressure difference ΔP between the pressure P4 and the pressure P3 when the inhalation valve starts to close are determined, and the pressure difference ΔP is compared with the set pressure difference threshold ΔP. v When the pressure difference ΔP is greater than the set pressure difference threshold ΔP vWhen , go to step S290, otherwise, return to step 220.

[0074] In step 290, the current cycle is taken as the marking cycle, the number of consecutive marking cycles in a single control stage S is determined, and the number of consecutive marking cycles in a single control stage S is compared with the second number threshold F2. v2 (In this embodiment, F v2 =2) for comparison. If the number of consecutive marking cycles F2 reaches the second number threshold F v2 , then go to step 300, otherwise, return to step 220.

[0075] In step 300, the control device stops the charging and suction assistance and issues a leakage alarm.

[0076] The above method can accurately identify the leakage of the airway tube. It should be pointed out that the duration Δt mentioned in the above method can have different durations in different steps and the duration is less than the duration of the inhalation phase of a single cycle. The duration Δt mentioned when judging the leakage of the catheter can also be different from the duration used when judging the detachment, and its range can be set according to specific needs.

[0077] Used to determine the set pressure difference threshold ΔP of the gas line pipe leakage v It can be determined experimentally. For example, the PVAD is placed in a specific flow fixture, and then the PVAD catheter is connected to a tee, one of the interfaces of the tee is connected to an adjustable flow limiting valve to simulate different leakage rates.

[0078] Next, measure the flow impact. Insert the PVAD catheter into the flow test fixture and load it with 100mmgh water column. Inflate the device at 60 heart rates and adjust the leakage knob at the same time to find a state with leakage and obvious flow reduction. For example, a flow rate of 5% leakage compared to the flow rate without leakage can be used. In this state, record the leakage valve flow limit setting position.

[0079] Then, the leakage characteristics are found, and when the flow limiting valve is in the leakage state at the above position, the PVAD catheter pressure data is recorded and the threshold characteristics are analyzed. Fig. 9The pressure waveform analysis diagram for determining the leakage judgment threshold is shown. Figures (a) and (b) compare the pressure values ​​and change trends in the inflation stage and the inhalation stage. Figure (a) shows the pressure waveform when there is no leakage, and Figure (b) shows the pressure waveform when there is leakage. It can be seen from the figure that there is no obvious difference in pressure between leakage and no leakage, whether in the inflation stage or the inhalation stage, and it cannot be used as a basis for leakage judgment. Figures (c) and (d) show the pressure changes after the negative pressure valve is closed during the preset period of the inhalation stage. Figure (c) shows the pressure waveform when there is no leakage, and Figure (d) shows the pressure waveform when there is leakage. Comparing the two figures, it can be seen that the pressure rise slope of leakage is approximately twice that of no leakage. When the time is extended, as shown in Figure (e) (corresponding to no leakage) and Figure (f) (corresponding to leakage), the rising pressure of the no-leak catheter is within 6kpa, while the pressure of leakage can rise to 44kpa, close to atmospheric pressure. Therefore, the leakage and no-leak states show obvious differences after the negative pressure valve is closed.

[0080] Moreover, the set pressure difference threshold ΔP for judging the leakage of the gas line pipe can be determined based on the above method. v , that is, using the above-mentioned flow test tool to simulate the pressure difference changes under various leakage conditions, and determine the pressure difference threshold ΔP based on the simulation v In one embodiment, the pressure difference threshold ΔP is set v is a fixed value, such as 10 kPa. Optionally, in another embodiment, the pressure difference threshold ΔP is set v is the change value related to the pressure P3 at the time t3 when the negative pressure valve starts to close, for example, the pressure difference threshold ΔP is set v can be equal to one third of the pressure P3, that is, ΔP v =P3 / 3.

[0081] Optionally, in some embodiments, the method for determining abnormal air tightness of the airway tube of the percutaneous left ventricular assist device according to the present invention may further include determining the severity of the airway tube leakage. For example, setting the pressure difference threshold ΔP v A first pressure difference threshold ΔP may be included v1 , the second pressure difference threshold ΔP v2 and the third pressure difference threshold ΔP v3 The three pressure difference thresholds correspond to the critical values ​​of low leakage (for example, leakage of 3%-5%), medium leakage (for example, leakage of 5%-10%) and high leakage (for example, leakage of more than 10%). In response to the pressure difference ΔP being greater than the first pressure difference threshold ΔP v1 and is less than the second pressure difference threshold ΔP v2 In response to the pressure difference ΔP being greater than the second pressure difference threshold ΔP v2 and is less than the third pressure difference threshold ΔP v3In response to the pressure difference ΔP being greater than the third pressure difference threshold ΔP v3 The leakage is determined to be a high leakage. The specific flow tool as described above can be used to determine the demarcation threshold corresponding to each leakage degree.

[0082] Another object of the present invention is to provide a system for determining abnormal air tightness of a percutaneous left ventricular assist device airway tube, the system comprising at least one memory and at least one processor, wherein the at least one memory is used to store a machine-readable program, and the at least one processor is used to call the machine-readable program to execute the method according to any of the above embodiments.

[0083] The above-mentioned embodiments only express the implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. It should be pointed out that for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A method for determining abnormal air tightness of a percutaneous left ventricular assist device airway tube, characterized in that: The following steps are involved: Periodically controlling the inflation and inspiration of the percutaneous left ventricular assist device; Real-time collection of the pressure P in the airway tube of the percutaneous left ventricular assist device; The pressure P of the negative pressure stage of the airway tube caused by the suction control N An analysis is performed to determine whether there is any abnormality in the air tightness of the air line tube.

2. The method for determining abnormal air tightness of a percutaneous left ventricular assist device airway tube according to claim 1, characterized in that: Determining whether there is an abnormality in the air tightness of the air circuit tube includes determining whether the air circuit tube falls off and / or whether the air circuit tube leaks.

3. The method for determining abnormal air tightness of a percutaneous left ventricular assist device airway tube according to claim 2, characterized in that: Determining whether the airway tube has fallen off includes: In a single inflation / inhalation cycle, after switching from the inflation control to the inhalation control and after a first preset period T1, the pressure P in the airway tube is periodically collected. N With pressure threshold P v By comparison, the pressure P in the airway tube during a single filling and suction cycle is N Exceeding the pressure threshold P v The number of times is accumulated, and the accumulated number F1 is compared with the first number threshold F v1 In response to the cumulative number F1 exceeding the first number threshold F v1 It is determined that the airway tube is abnormally detached.

4. The method for determining abnormal air tightness of a percutaneous left ventricular assist device airway tube according to claim 3, characterized in that: The pressure threshold P v It is determined based on a dynamic threshold line, and the dynamic threshold line is obtained based on a model, and the model is a relationship model between the air pressure threshold and time in the negative pressure stage.

5. The method for determining abnormal air tightness of a percutaneous left ventricular assist device airway tube according to claim 4, characterized in that: The dynamic threshold line changes linearly, and the dynamic threshold line can be determined by the first moment t1, the second moment t2, the abnormal pressure threshold P1 corresponding to the first moment t1, and the abnormal pressure threshold P2 corresponding to the second moment, wherein the first moment t1 is the moment after the first preset time period T1 has passed after the inflation control is switched to the suction control, and the second moment t2 is the starting moment when the rate of change of the pressure in the air circuit tube becomes less than the set value when there is a falling-off abnormality.

6. The method for determining abnormal air tightness of a percutaneous left ventricular assist device airway tube according to claim 3, characterized in that: The method further includes determining whether to switch from the charging control to the suction control based on a preset control sequence.

7. The method for determining abnormal air tightness of a percutaneous left ventricular assist device airway tube according to claim 2, characterized in that: Determining whether the gas line tube is leaking includes: N consecutive charging and inhalation cycles are grouped together, and M consecutive cycles in a group are selected as a single control stage S. In the control stage S, the inhalation valve connected to the air circuit pipe is closed in the selected time period T2 of the inhalation stage of each charging and inhalation cycle, and the pressure difference ΔP between the pressure P4 at the end time t4 of the selected time period T2 and the pressure P3 at the start time t3 is determined, and the pressure difference ΔP is compared with the set pressure difference threshold ΔP. v When the pressure difference ΔP is greater than the set pressure difference threshold ΔP v When the period is taken as the marking period, in response to the number F2 of consecutive marking periods in a single control stage S reaching the second number threshold F v2 And determine that the gas line tube is leaking.

8. The method for determining abnormal air tightness of a percutaneous left ventricular assist device airway tube according to claim 7, characterized in that: The end time t4 of the selected time period T2 is the end time of the inhalation phase, and the duration of the selected time period T2 is 50-200 ms.

9. The method for determining abnormal air tightness of a percutaneous left ventricular assist device airway tube according to claim 7, characterized in that: The method further includes determining the severity of the gas line tube leakage, wherein the set pressure difference threshold ΔP v Including the first pressure difference threshold ΔP v1 , the second pressure difference threshold ΔP v2 and the third pressure difference threshold ΔP v3 , in response to the pressure difference ΔP being greater than the first pressure difference threshold ΔP v1 and is less than the second pressure difference threshold ΔP v2 The leakage is determined to be low leakage, in response to the pressure difference ΔP being greater than the second pressure difference threshold ΔP v2 and is less than the third pressure difference threshold ΔP v3 The leakage is determined to be a medium leakage, in response to the pressure difference ΔP being greater than the third pressure difference threshold ΔP v3 The leak is determined to be a high leak.

10. A system for determining abnormal air tightness of a percutaneous left ventricular assist device airway tube, characterized in that: The system comprises: at least one memory for storing a machine-readable program; At least one processor, configured to call the machine-readable program to execute the method according to any one of claims 1 to 9.

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