Cardiopulmonary resuscitation device and control method, device therefor

Abstract

This application relates to a cardiopulmonary resuscitation (CPR) device and its control method and apparatus. The method includes: outputting a compression command to a compression machine and recording the number of compression command outputs; when the number of outputs reaches a preset value, outputting a delay command to the compression machine and a ventilation command to the ventilator to instruct the ventilator to perform ventilation while the compression machine is in the compression state; and, after confirming that the ventilator has completed the ventilation command and the compression machine has completed the delay command, resetting the number of outputs to zero and returning to the steps of outputting compression commands to the compression machine and recording the number of compression command outputs. This method enables the ventilator and compression machine to work together, effectively avoiding the problem of high airway pressure injury that easily occurs when ventilation and compression operations conflict, and improving the success rate of CPR.

Description

Technical Field

[0001] This application relates to the field of medical device technology, and in particular to a cardiopulmonary resuscitation device and its control method and apparatus. Background Technology

[0002] CPR (Cardiopulmonary Resuscitation) is a fundamental and crucial medical method for rescuing patients experiencing cardiac arrest. CPR typically involves a combination of chest compressions and intermittent positive pressure ventilation to maintain basic blood circulation and promote the restoration of heartbeat and breathing.

[0003] Existing cardiopulmonary resuscitation (CPR) devices typically consist of two core components: chest compression equipment and ventilation (breathing) equipment. Although chest compression machines and ventilators can perform corresponding CPR actions independently in clinical hospital settings, there are still shortcomings in coordinated control. Currently, ventilation decisions are mostly based on ventilator feedback flow or pressure signals, which results in response delays, leading to conflicts between ventilation and compression operations, and increasing the risk of high airway pressure injury, thus affecting the overall success rate of CPR. Summary of the Invention

[0004] Therefore, it is necessary to provide a cardiopulmonary resuscitation device and its control method and apparatus that can improve the success rate of cardiopulmonary resuscitation in response to the above-mentioned technical problems.

[0005] In a first aspect, this application provides a control method for a cardiopulmonary resuscitation (CPR) device. The method is applied to a control module in the CPR device, which includes a control module and a ventilator and a chest compression device that are interconnected and respectively connected to the control module. The method includes:

[0006] Output a press command to the press machine and record the number of times the press command is output; the press command is used to instruct the press machine to press.

[0007] When the number of outputs reaches a preset value, a delay command is output to the presser and a ventilation command is output to the ventilator. The delay command is used to instruct the presser to maintain the pressing state for a first duration, and the ventilation command is used to control the ventilator to trigger the ventilation action for a second duration. The first duration is greater than or equal to the second duration.

[0008] Once it is confirmed that the ventilator has completed the ventilation command and the compression device has completed the delay command, the output count is reset to zero, the compression command is returned to the compression device, and the number of compression commands is recorded.

[0009] In one embodiment, the ventilator is equipped with an airway pressure sensor; the method further includes:

[0010] It receives pressure data from the airway pressure sensor. When the pressure data reaches a preset pressure threshold, it outputs a protection command to the ventilator and performs protection operations.

[0011] The protection command is used to instruct the ventilator to terminate the current ventilation action; the protection operation includes adjusting the ventilation parameters based on the pressure data, and the ventilation parameter adjustment includes at least one of adjusting the preset pressure threshold, adjusting the target tidal volume of the ventilator, and adjusting the gas flow rate of the ventilator.

[0012] In one embodiment, the ventilation command is also used to instruct the ventilator to ventilate in an exponentially decreasing manner with gas flow rate.

[0013] In one embodiment, the gas flow rate V(t) is as follows:

[0014] V(t) = V0.e –kt ;

[0015] Where t is time in seconds; V0 is the initial flow velocity; and k is the decrease coefficient.

[0016] In one embodiment, the preset values ​​include 10, 15, and 30.

[0017] Secondly, this application also provides a control device for a cardiopulmonary resuscitation (CPR) device. The device is applied to a control module within the CPR device, which includes a control module and a ventilator and chest compression machine respectively connected to the control module. The device includes:

[0018] The first output module is used to output a pressing command to the pressing machine and record the number of times the pressing command is output; wherein, the pressing command is used to instruct the pressing machine to press;

[0019] The second output module is used to output a delay command to the presser and a ventilation command to the ventilator when the number of outputs reaches a preset value. The delay command is used to instruct the presser to maintain the pressing state for a first duration, and the ventilation command is used to instruct the ventilator to perform ventilation for a second duration. The first duration is greater than or equal to the second duration.

[0020] The status judgment module is used to reset the output count to zero, return to the presser to execute the press command, and record the number of press commands when it is determined that the ventilator has completed the execution of the ventilation command and the presser has completed the execution of the delay command.

[0021] Thirdly, this application also provides a cardiopulmonary resuscitation device, including a control module, and a ventilator and a compression device respectively connected to the control module;

[0022] The control module is used to implement the steps of the above method.

[0023] In one embodiment, the cardiopulmonary resuscitation device further includes:

[0024] The communication module connects to the control module, ventilator, and compression device, respectively.

[0025] In one embodiment, the communication module connects to the ventilator and the compression device respectively via Bluetooth communication protocol.

[0026] In one embodiment, the communication module is connected to the ventilator and the pump via WIFI communication, CAN bus communication, and Zigbee communication, respectively.

[0027] Fourthly, this application also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the above-described method.

[0028] The aforementioned cardiopulmonary resuscitation device and its control method / device output compression commands to the compression machine and record the number of compression command outputs. When the number of outputs reaches a preset value, a delay command is output to the compression machine and a ventilation command is output to the ventilator, instructing the ventilator to provide ventilation while the compression machine maintains the compression state. Once it is confirmed that the ventilator has completed the ventilation command and the compression machine has completed the delay command, the output count is reset to zero, and the process returns to outputting compression commands to the compression machine and recording the number of compression command outputs. This application, by controlling the ventilator to provide ventilation while the compression machine maintains the compression state when the recorded number of compression command outputs reaches a preset value, and initiating the next round of compressions when it is confirmed that the ventilator has completed ventilation and the compression machine has completed the delayed compression, achieves coordinated operation between the ventilator and the compression machine, enabling safe and effective synchronized ventilation support during continuous compression. This effectively avoids the high airway pressure injury problem caused by ventilation and compression conflicts, improves the success rate of cardiopulmonary resuscitation, and is applicable to in-hospital emergency treatment, simulation training, and other scenarios. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of this application or related technologies, the drawings used in the description of the embodiments of this application or related technologies will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a schematic diagram of the operation of a cardiopulmonary resuscitation device in one embodiment;

[0031] Figure 2This is a flowchart illustrating the control method of a cardiopulmonary resuscitation device in one embodiment;

[0032] Figure 3 This is a schematic diagram of the operation logic of a cardiopulmonary resuscitation device in one embodiment;

[0033] Figure 4 This is a schematic diagram of the signal of a cardiopulmonary resuscitation device in one embodiment;

[0034] Figure 5 This is a diagram showing the overall operation mode and trigger feedback of a cardiopulmonary resuscitation device in one embodiment.

[0035] Figure 6 This is a schematic diagram of the gas flow rate of a ventilator in one embodiment;

[0036] Figure 7 This is a schematic diagram illustrating the compression status of the chest compression machine and the ventilation status of the ventilator in a cardiopulmonary resuscitation device in one embodiment;

[0037] Figure 8 This is a structural block diagram of the control device of a cardiopulmonary resuscitation device in one embodiment;

[0038] Figure 9 This is a structural block diagram of a cardiopulmonary resuscitation device in one embodiment;

[0039] Figure 10 This is a waveform diagram corresponding to the parameters in a ventilator in one embodiment;

[0040] Figure 11 This is a structural block diagram of the cardiopulmonary resuscitation device in another embodiment;

[0041] Figure 12 This is a schematic diagram of the state transition of a cardiopulmonary resuscitation device in one embodiment;

[0042] Figure 13 This is an internal structural diagram of a computer device in one embodiment. Detailed Implementation

[0043] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0044] It is understood that the terms “first,” “second,” etc., as used herein may be used to describe various elements, but these elements are not limited by these terms. These terms are used only to distinguish one element from another. When used herein, the singular forms of “a,” “an,” and “the” may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising / including” or “having,” etc., specify the presence of the stated features, integrals, steps, operations, components, parts, or combinations thereof, but do not preclude the possibility of the presence or addition of one or more other features, integrals, steps, operations, components, parts, or combinations thereof.

[0045] The survival rate of patients undergoing cardiopulmonary resuscitation (CPR) is significantly affected by the quality of compressions / ventilation using CPR devices. The European Resuscitation Committee's resuscitation guidelines specifically emphasize the importance of performing high-quality chest compressions with minimal interruptions and early chest compressions during CPR. However, the three key issues of optimal frequency, optimal volume, and airway pressure management remain highly controversial. At the same time, there is also great heterogeneity in the clinical practice of compression / ventilation strategies, with multiple study respondents indicating that they often ignore the guidance of ventilation guidelines.

[0046] AMCCD (Automatic Mechanical Cardiopulmonary Resuscitation Device, also known as a chest compression machine) is designed to meet the requirements for continuous and reliable cardiopulmonary resuscitation performance. Therefore, when manual chest compressions are difficult to achieve or endanger the safety of the chest compressionr, current guidelines recommend an automated mechanical chest compression device as a reasonable alternative. Various respiratory support modes for ACLS (Advanced Cardiovascular Life Support) have been reported, including BIPAP (Biphasic Positive Airway Pressure), CPAP (Continuous Positive Airway Pressure), VCV (Volume Controlled Ventilation), CCSV (Chest Compression Synchronized Ventilation), PRVC (Pressure Regulated Volume Control), and continuous compression without mechanical ventilation, among other highly diverse compression / ventilation modes. Although most studies suggest that all ventilation modes can achieve adequate minute ventilation, the risk of barotrauma increases due to the high inspiratory pressure and asynchronous chest compressions during mechanical ventilation, i.e., the conflict between ventilation and compression, which affects the success rate of cardiopulmonary resuscitation.

[0047] Currently, there is a lack of high-quality research to verify the optimal mechanical ventilation treatment effect in ACLS, and the coupling and linkage effect between AMCCD and mechanical ventilation has not been focused on. Therefore, if the optimal mechanical ventilation mode can be achieved by establishing a synchronous ventilation mode under continuous compression based on the concept of "bionics" with the goal of matching the "compression / ventilation" ratio, and by obtaining effective perfusion / ventilation ratio feedback through chest impedance monitoring to adjust ventilation support, and finally forming a mechanical support treatment system after cardiac arrest, thereby improving the quality of cardiopulmonary resuscitation and reducing the mortality rate after cardiac arrest, it will have extremely important clinical and social value.

[0048] It is important to note that standard cardiopulmonary resuscitation (CPR) includes manual chest compressions to maintain blood flow and positive pressure ventilation to maintain oxygenation until spontaneous circulation is restored. During out-of-hospital cardiac arrest, ventilation is often interrupted by chest compressions; frequent interruptions reduce cardiac blood flow and may decrease the effectiveness of CPR. Therefore, the current strategy for minimizing compression interruptions remains providing asynchronous positive pressure ventilation without pausing compressions. However, a large study comparing 30:2 (two ventilations after every 30 chest compressions) and continuous chest compression with asynchronous positive pressure ventilation (CCC-CPR) in out-of-hospital cardiac arrest patients found no difference in survival between the two groups. However, analysis of secondary outcomes revealed that the 30:2 group had higher admission survival and more days of out-of-hospital survival, suggesting that compression / ventilation patterns may influence patient outcomes. However, high-quality evidence is currently lacking regarding the optimal compression / ventilation pattern during CPR. Multiple studies observing patients hospitalized for causes other than cardiac arrest (such as acute respiratory distress syndrome) have found that tidal volume and airway pressure increase the likelihood of lung injury (e.g., barotrauma) and death. A peak inspiratory pressure of 30 cmH2O is commonly used as a protective threshold for mechanical ventilation. A preliminary study measuring ventilation during OHCA (Out-of-Hospital Cardiac Arrest) found that airway pressure is typically higher during chest compressions compared to ventilation during compression pauses. The same study also found that inspiratory pressures achieved in CCC-CPR typically exceed the safe threshold of 30 cmH2O, and tidal volumes delivered during continuous chest compressions are generally lower than those delivered during pauses. This suggests that ventilation during compression pauses (where ventilation does not conflict with compression) effectively avoids high airway pressure injury, thereby improving cardiopulmonary resuscitation success rates.

[0049] The control method for the cardiopulmonary resuscitation device provided in this application embodiment can be applied to, for example... Figure 1In the application scenario shown, the control module is connected to both the ventilator and the chest compression machine. Based on preset parameters, the control module periodically outputs compression commands to the chest compression machine and records the number of compression commands output in real time. When the number of outputs recorded by the control module reaches a preset value, it outputs a delay command to the chest compression machine and a ventilation command to the ventilator. This instructs the ventilator to provide ventilation while the chest compression machine maintains the compression position. Once the ventilator has completed ventilation and the chest compression machine has completed the delayed compression, the next round of compressions begins. This achieves coordinated operation between the ventilator and the chest compression machine, effectively reducing high airway pressure injuries caused by conflicts between ventilation and compression operations, thereby improving the success rate of cardiopulmonary resuscitation.

[0050] In one exemplary embodiment, such as Figure 2 As shown, a control method for a cardiopulmonary resuscitation device is provided, which is applied to... Figure 1 The method is illustrated using the control module of a central lung resuscitation device as an example, including:

[0051] S202, outputs a pressing command to the pressing machine and records the number of times the pressing command is output; wherein, the pressing command is used to instruct the pressing machine to press.

[0052] Specifically, the control module periodically outputs pressing commands to the presser according to a preset mode (such as continuous pressing, 10:1, 30:2, etc.) and records the number of times the pressing commands are output, that is, records the number of presses by the presser. The presser performs pressing at a preset depth (such as 5cm) and frequency (such as 100 times / min) based on the received pressing commands. It should be noted that the above preset modes and parameters can be adjusted according to the actual situation of the patient and are not limited in this embodiment.

[0053] It should be noted that after each press, the compression machine sends a completion signal to the control module. The control module then accumulates the number of presses and, upon detecting the nth press (where n is a preset value, such as n=10), triggers the ventilator's ventilation operation during the compression machine's rebound period. Specifically, it outputs a delay command to the compression machine to maintain the compression position and a ventilation command to the ventilator to initiate a single ventilation action, achieving strict timing coordination between the two machines.

[0054] For example, the operational logic diagram of a cardiopulmonary resuscitation device can be as follows: Figure 3 As shown, the chest compression machine and ventilator can connect via Bluetooth. Once the control device (backend) confirms that a low-latency wireless connection has been established between the ventilator and chest compression machine via Bluetooth, medical personnel can initiate Bio-CPR (continuous chest compressions-synchronized intermittent ventilation) mode with a single button press. The cardiopulmonary resuscitation device then enters the default ventilation mode (VCV), where the target tidal volume (V) is... tThe inhalation volume was set to 350 ml, and the inspiratory time (T) was... i The breathing time was set to 0.6 seconds, the inhaled oxygen concentration (FiO2) to 100%, and the positive end-expiratory pressure (PEEP) to 4 cmH2O. These parameters can be adjusted flexibly according to the patient's condition and guidelines.

[0055] like Figure 3 As shown, the compression / ventilation ratio can be flexibly set according to actual needs. This embodiment uses a 10:1 ratio (one ventilation after every 10 chest compressions) as an example. It should be noted that when the CPR device is in the default ventilation mode, the control module continuously monitors the Bluetooth connection. When Bluetooth is detected as not connected (no trigger signal for more than 8 seconds), the control module automatically switches the CPR device to the backup ventilation mode (Assist Control ventilation, abbreviated as AC). In this mode, the target tidal volume is set to 420 ml, the inspiratory time is set to 1.0 second, the respiratory rate (RR) is set to 16 breaths / minute (bpm), and the positive end-expiratory pressure is set to 4 cmH2O. Medical staff can manually switch to the standby ventilation mode or enter other modes, such as PCV (Pressure Controlled Ventilation) mode and PRVC (Pressure Regulated Volume Control) mode, to meet the needs of different clinical scenarios. These will not be elaborated in the embodiments of this application.

[0056] S204, when the number of outputs reaches a preset value, a delay command is output to the presser and a ventilation command is output to the ventilator; wherein, the delay command is used to instruct the presser to maintain the pressing state for a first duration, and the ventilation command is used to control the ventilator to trigger the ventilation action for a second duration, wherein the first duration is greater than or equal to the second duration.

[0057] The preset value can be set according to the actual situation. In this embodiment, the preset value is 10 as an example. The first duration and the second duration can both be set according to the actual situation. In this embodiment, the first duration is 0.9 seconds and the second duration is 0.9 seconds as an example.

[0058] Specifically, when the number of outputs reaches a preset value, the control module simultaneously outputs a delay command and a ventilation command. Based on the received delay command, the chest compression machine delays its retraction to the top and stops after a delay at the top; that is, the chest compression machine maintains the compression state for the first duration. Based on the received exhalation command, the ventilator delivers continuous air to the patient for a second duration while the chest compression machine maintains the compression state. This design ensures that the entire ventilation process is performed in a stable chest cavity, effectively reducing the risk of high airway pressure and lung injury caused by overlapping ventilation and compression operations.

[0059] S206, after determining that the ventilator has completed the ventilation and delivery command and the compression machine has completed the delay command, the output count is cleared to zero, and the process of returning to the compression machine to execute the compression command is recorded.

[0060] Specifically, the control module can monitor the working status of the compression machine and ventilator in real time. When it detects that the ventilator has completed the ventilation operation and the compression machine has completed the retraction, it will reset the output count to zero and instruct the cardiopulmonary resuscitation device to enter the next cycle of compressions. That is, the control module strictly follows the principle of "not starting the next compression until ventilation is finished", so that the compression operation and ventilation operation do not interfere with each other. This effectively avoids the problem of high airway pressure injury that is prone to occur when ventilation and compression operations conflict, and improves the success rate of cardiopulmonary resuscitation.

[0061] It should be noted that, in order to ensure that the compression machine has completed the ventilation operation, the control module can wait for a third time after confirming that the ventilator has completed the ventilation command and the compression machine has completed the delay command before returning to execute the compression command to the compression machine and recording the number of compression commands output. This ensures that the compression operation and the ventilation operation do not overlap, thereby improving the success rate of cardiopulmonary resuscitation. The third time can be set according to the actual situation. In this embodiment, the third time is 0.3 seconds as an example.

[0062] In the aforementioned cardiopulmonary resuscitation device and its control method, during continuous mechanical chest compressions, a preset compression / ventilation ratio is established (i.e., ventilation is triggered after each preset compression value), and a delay command is introduced. This delay command achieves strict timing interlock between the chest compression machine and the ventilator, instructing the chest compression machine to maintain the compression state for a first duration, and simultaneously instructing the ventilator to perform ventilation for a second duration within the first duration. The next round of compressions is initiated only after confirming that the ventilator has completed ventilation and the chest compression machine has completed the delayed compression. This achieves seamless interlocking between the ventilator and the ventilator. The coordinated operation of the compression machine effectively avoids the high airway pressure injury that can easily occur when ventilation and compression operations conflict, thus improving the success rate of cardiopulmonary resuscitation (CPR). At the same time, this CPR device is compatible with various compression / ventilation ratios (such as 30:2, 15:2, 10:1, etc.) and various ventilation modes (VCV, PCV, PRVC, etc.), and has good scalability and intelligent upgrade potential. It can integrate an AI adaptive parameter optimization module, which significantly improves the safety, coordination, and resuscitation efficiency during CPR, and has broad prospects for clinical application and industrialization.

[0063] In one embodiment, the ventilator is equipped with an airway pressure sensor; the method further includes:

[0064] It receives pressure data from the airway pressure sensor. When the pressure data reaches a preset pressure threshold, it outputs a protection command to the ventilator and performs protection operations.

[0065] The protection command is used to instruct the ventilator to terminate the current ventilation action; the protection operation includes adjusting the ventilation parameters based on the pressure data, and the ventilation parameter adjustment includes at least one of adjusting the preset pressure threshold, adjusting the target tidal volume of the ventilator, and adjusting the gas flow rate of the ventilator.

[0066] The model of the airway pressure sensor can be set according to the actual situation, as long as it can realize the function of collecting pressure data corresponding to the airway pressure; the preset pressure threshold can be set according to the actual situation. In this embodiment, the preset pressure threshold is 30cmH2O as an example for explanation.

[0067] Specifically, the control module receives the patient's pressure data collected by the airway pressure sensor and compares the pressure data with a preset pressure threshold. When the pressure data reaches the preset pressure threshold, the ventilator will immediately take protective action: terminate the current air delivery in advance to prevent the pressure from rising further and causing lung damage.

[0068] When the pressure data reaches the preset pressure threshold, the control module records the high-pressure event and can automatically fine-tune the gas delivery parameters (such as reducing the target tidal volume or ventilation velocity) in subsequent ventilation cycles based on this feedback information, thereby achieving adaptive pressure control based on pressure feedback.

[0069] It should be noted that adjusting the gas flow rate of the ventilator includes adjusting the initial flow rate and the reduction coefficient to achieve an adaptive pressure control mechanism.

[0070] In this embodiment, by setting a preset pressure threshold, an adaptive "semi-closed-loop" ventilation pressure support mode is formed using airway high pressure protection as an "open-loop" protection mode to reduce high airway pressure injuries. Specifically, during mechanical ventilation, the control module monitors pressure data in real time. When the pressure data reaches the preset pressure threshold, a protection command is output to the ventilator to instruct it to stop ventilation, thus preventing further pressure increases that could cause lung injury and improving the success rate of cardiopulmonary resuscitation. Simultaneously, when the pressure data reaches the preset pressure threshold, a protection operation is executed. This operation includes fine-tuning the delivery parameters, such as reducing the target tidal volume or initial ventilation rate, to achieve adaptive pressure control and prevent the same problem from recurring during subsequent ventilation, further improving the success rate of cardiopulmonary resuscitation.

[0071] To facilitate understanding by those skilled in the art, the control method of the cardiopulmonary resuscitation device is explained below with reference to two specific examples, such as... Figure 4 As shown, Figure 4 The upper half of the diagram is used to show how the signal reception of the presser changes over time. The presser periodically receives the pressing command, that is, the presser receives the pressing command at point ① (the lowest point) and presses, at which point the number of outputs reaches the preset value (the 10th time). Figure 4 The lower half of the graph represents the change in ventilation status of the ventilator over time. When the number of breaths reaches a preset value, the ventilator receives a ventilation command at point ② and performs a ventilation cycle lasting for a duration of T. i (Second duration) of ventilation, Figure 4 Point ③ in the diagram indicates that after receiving the delay instruction, the presser maintains the pressing state for the first duration. Once it is determined that the ventilator has completed the ventilation instruction and the presser has completed the delay instruction, the output count is reset to zero, and the next round of pressing begins.

[0072] Figure 5 An exemplary schematic diagram illustrating the overall operating logic and triggering of a cardiopulmonary resuscitation (CPR) device is provided. Figure 5Figure A illustrates the timing coordination of chest compressions and ventilation: The chest compression machine performs compressions at a fixed interval (e.g., 100 compressions / minute) to a depth of 5 cm. On the 10th compression (preset value), reaching the minimum displacement point (5 cm), the machine retracts to its original position and pauses for 0.9 seconds (first duration). During this 0.9-second pause, the ventilator performs ventilation. During ventilation, the chest compression machine retracts from the minimum compression depth (5 cm) and maintains this position. After the ventilator completes ventilation, after a 0.3-second delay (third duration), the control module sends a compression command to the chest compression machine. Upon receiving this command, the machine ends its pause and begins the next compression cycle.

[0073] Figure 5 Figure B illustrates ventilation triggering and pressure monitoring: When the ventilator reaches its 10th compression (preset value) and the deepest point (5cm), the control module automatically sends a ventilation command to the ventilator via Bluetooth synchronization. Upon receiving the ventilation command, the ventilator immediately triggers a ventilation action. The ventilator is equipped with an airway pressure sensor to collect and monitor the patient's airway pressure in real time. Peak Inspiratory Pressure (PIP) refers to the highest pressure value reached in the airway during a single inspiratory (ventilation) cycle. Its main functions include reflecting respiratory system resistance and compliance, providing early warning of barotrauma risk, assessing ventilation effectiveness, and triggering protection mechanisms. The peak inspiratory pressure can be the same as a preset pressure threshold.

[0074] Figure 5 Figure C shows a ventilator volume waveform: illustrating the volume-time waveform during a single ventilation cycle. Inspiratory phase: Upon receiving the ventilation command, the waveform rises rapidly, representing the delivery of gas into the patient's lungs. The amplitude of the rise represents the tidal volume (Vt) delivered, for example, a target of 450 ml (depending on the selected mode parameters). The slope or shape of the rise (e.g., a decrementing wave) reflects changes in the inspiratory flow rate. The duration of the inspiratory phase is the set T1. i Expiratory phase: After the inspiratory phase, the waveform shows a natural downward trend (usually an exponential decay pattern), representing the passive exhalation of gas from the patient's lungs.

[0075] It should be noted that in Bio-CPR mode, the respiratory rate is determined by the compression cycle of the chest compression machine and the set compression / ventilation ratio (10:1). The frequency displayed on the waveform should be consistent with this, ensuring that each ventilation is performed at the lowest point of compression. Waveform significance: This waveform is an important tool for monitoring whether ventilation is performed according to the set parameters (tidal volume, inspiratory time, respiratory rate, and presence of air leaks / gas trapping).

[0076] In one embodiment, the ventilation command is also used to instruct the ventilator to ventilate in an exponentially decreasing manner at the gas flow rate.

[0077] Specifically, the ventilator supports a decreasing waveform ventilation mode. The ventilation command is not only used to trigger the ventilator to deliver gas, but also to instruct the ventilator to ventilate in an exponentially decreasing manner with gas flow rate. That is, the gas flow rate decreases exponentially over time, which is superior to the traditional constant flow or constant pressure ventilation mode and can effectively reduce peak inspiratory pressure and improve lung compliance.

[0078] In this embodiment, by instructing the ventilator to perform ventilation in an exponentially decreasing manner, the peak pressure during ventilation is reduced, and the ventilation is interrupted in a timely manner at a high pressure warning threshold (a preset pressure threshold, such as 30 cmH2O), thereby reducing the risk of barotrauma and improving the success rate of cardiopulmonary resuscitation.

[0079] In one embodiment, the gas flow rate V(t) is as follows:

[0080] V(t) = V0.e -kt ;

[0081] Where t is time in seconds; V0 is the initial flow velocity; and k is the decrease coefficient.

[0082] The initial flow rate can be set according to actual conditions and is not limited in this embodiment; the decrease coefficient can be set according to actual conditions, and in this embodiment, the decrease coefficient can range from 0.5 to 1.5 s. -1 .

[0083] Specifically, it can be dynamically optimized based on the patient's lung compliance and pressure feedback to adjust the initial flow rate and deceleration coefficient, thereby improving lung compliance and increasing the success rate of cardiopulmonary resuscitation.

[0084] For example, the decreasing waveform gas flow rate of the ventilator can be as follows: Figure 6 As shown.

[0085] In one embodiment, the preset values ​​include 10, 15, and 30.

[0086] Specifically, the ratio of chest compressions to ventilations can be any one of 10:1 (1 ventilation after every 10 chest compressions), 30:2 (2 ventilations after every 30 chest compressions), or 15:2 (2 ventilations after every 15 chest compressions), and this ratio is dynamically set by the control module according to the patient's condition or preset parameters.

[0087] To facilitate understanding by those skilled in the art, the control method of the cardiopulmonary resuscitation device is applied to a porcine animal model experiment with cardiac arrest using a specific example for verification and explanation. The experimental results are as follows: Figure 7 As shown. Figure 7 It is divided into four parts, from top to bottom, showing the raw data of the impedance signal, the extraction of the respiratory waveform, the comparison between the respiratory waveform and the fitted curve, and the change of the area under the respiratory waveform curve.

[0088] The top subplot shows the raw impedance signal collected at the 10th minute of the experiment, with the horizontal axis representing the sampling point and the vertical axis representing the impedance (Ohm). The signal exhibits obvious periodic fluctuations, reflecting the alternating effects of chest compressions and ventilation during cardiopulmonary resuscitation.

[0089] The second subplot extracts the respiratory waveform from the original signal using wavelet transform, with the horizontal axis representing time (seconds) and the vertical axis representing impedance (Ohms). The variation of the respiratory waveform within each cycle can be observed.

[0090] The third subplot compares the extracted respiratory waveform (blue line) with the curve (red line) fitted based on the exponentially decreasing model. The fitted curve reflects the actual respiratory waveform's changing trend well, indicating that the model proposed in this application has high accuracy and applicability. As can be seen in the figure, the impedance signal exhibits a characteristic of first rising and then falling during each respiratory cycle, consistent with the physiological process of ventilator-assisted ventilation and passive regurgitation.

[0091] The bottom subplot shows the change in the area under the respiratory waveform curve; the periodic fluctuations in the area reflect the ventilation volume produced with each breath. This parameter can serve as an important indicator for assessing effective ventilation during cardiopulmonary resuscitation.

[0092] It should be understood that although the steps in the flowcharts of the embodiments described above are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the embodiments described above may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages in other steps. It is understood that the steps in different embodiments can be freely combined as needed, and all non-contradictory solutions formed by such combinations are within the scope of protection of this application.

[0093] Based on the same inventive concept, this application also provides a control device for a cardiopulmonary resuscitation (CPR) device used to implement the control method of the CPR device described above. The solution provided by this device is similar to the implementation described in the above method. Therefore, the specific limitations of one or more CPR device control device embodiments provided below can be found in the limitations of the control method for the CPR device described above, and will not be repeated here.

[0094] In one exemplary embodiment, such as Figure 8 As shown, a control device 800 for a cardiopulmonary resuscitation (CPR) device is provided. The device 800 is applied to a control module within the CPR device. The CPR device includes a control module, and a ventilator and a chest compression device respectively connected to the control module. The device 800 includes:

[0095] The first output module 801 is used to output a pressing command to the pressing machine and record the number of times the pressing command is output; wherein, the pressing command is used to instruct the pressing machine to press;

[0096] The second output module 802 is used to output a delay command to the presser and a ventilation command to the ventilator when the number of outputs reaches a preset value. The delay command is used to instruct the presser to maintain the pressing state for a first duration, and the ventilation command is used to instruct the ventilator to perform ventilation for a second duration. The first duration is greater than or equal to the second duration.

[0097] The determination module 803 is used to, when it is determined that the ventilator has completed the execution of the ventilation command and the presser has completed the execution of the delay command, clear the output count to zero, return to the presser to execute the output press command, and record the output count of the press command.

[0098] In one embodiment, the ventilator is equipped with an airway pressure sensor; the device 800 also includes a protection module for receiving pressure data transmitted by the airway pressure sensor and outputting a protection command to the ventilator when the pressure data reaches a preset pressure threshold; wherein the protection command is used to instruct the ventilator to terminate the current ventilation action.

[0099] In one embodiment, the protection module is further configured to perform a protection operation when the pressure data reaches a preset pressure threshold; the protection operation includes adjusting ventilation parameters based on the pressure data, the ventilation parameter adjustment including at least one of adjusting the preset pressure threshold, adjusting the target tidal volume of the ventilator, and adjusting the gas flow rate of the ventilator.

[0100] In one embodiment, the ventilation command is also used to instruct the ventilator to ventilate in an exponentially decreasing manner at the gas flow rate.

[0101] In one embodiment, the gas flow rate V(t) is as follows:

[0102] V(t) = V0.e –kt ;

[0103] Where t is time in seconds; V0 is the initial flow velocity; and k is the decrease coefficient.

[0104] In one embodiment, the preset values ​​include 10, 15, and 30.

[0105] The various modules in the control device of the aforementioned cardiopulmonary resuscitation device can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in the processor of a computer device in hardware form or independent of it, or stored in the memory of a computer device in software form, so that the processor can call and execute the corresponding operations of each module.

[0106] In one exemplary embodiment, a cardiopulmonary resuscitation device is provided, such as Figure 9 As shown, it includes a control module, and a ventilator and a compression device respectively connected to the control module;

[0107] The control module is used to implement the steps of the above method.

[0108] Specifically, the chest compression machine is used to perform chest compressions on the patient at a preset frequency. The chest compression machine is installed in the appropriate position and is used to compress the lower middle part of the patient's sternum. The chest compression machine is equipped with a display interface to display the compression depth, compression frequency, and compression mode. The ventilator is used to provide positive pressure ventilation during compressions. The ventilator is connected to the patient's airway through tubing and is also equipped with a display interface to display the ventilation mode, target tidal volume, inspiratory time, respiratory rate, and positive end-expiratory pressure.

[0109] It should be noted that the ventilator supports a decreasing waveform ventilation mode with a ventilation duration of 0.6 to 0.9 seconds and has a built-in pressure sensor to monitor airway pressure in real time. When the pressure exceeds the specified value (e.g., 30 cmH2O), the current ventilation is immediately interrupted, a protection mode is activated, and parameters are recorded for adjustment in the next ventilation cycle. This ventilation mode is superior to constant flow or constant pressure ventilation, effectively reducing pressure, protecting lung compliance, and improving lung compliance.

[0110] For example, in the validation experiment of the pig model of cardiac arrest, the waveforms of various ventilator parameters can be as follows: Figure 10As shown, the horizontal axis (X-axis) represents time (unit: seconds, s); the vertical axis (four channels): Channel 1: Airway pressure (unit: mbar, red); Channel 2: Airflow rate (unit: L / min, blue); Channel 3: Tidal volume (unit: mL, green); Channel 4: End-tidal carbon dioxide partial pressure (EtCO2, unit: mmHg, pink). Wherein, 1 mbar ≈ 1.02 cmH2O, 20 mbar ≈ 20.4 cmH2O.

[0111] Specifically, the four-channel waveform linkage analysis is as follows: During the inspiratory phase, the airflow rate (Flow, blue) shows a positive peak value, which then gradually decreases, exhibiting typical characteristics of volume-controlled ventilation (VCV) mode; the airway pressure (Pressure, red) simultaneously rises rapidly from the baseline to the peak value (approximately 18~20 mbar), showing an effective airway pressure establishment process; the tidal volume (Tidal Volume, green) rises rapidly from zero to the peak value (approximately 300 mL), consistent with the integral result of the airflow rate, reflecting the effective tidal volume increase process of each ventilation. During the expiratory phase, the airflow rate (Flow) rapidly turns negative (reaching as low as -30~-40 L / min), indicating the passive exhalation process; the airway pressure (Pressure) simultaneously falls back to the baseline level; the tidal volume (Tidal Volume) gradually decreases during exhalation, simulating the residual volume changes at the end of expiration in a healthy lung. The end-tidal carbon dioxide partial pressure (EtCO2, pink) gradually increases over time, exhibiting a stepwise change, reflecting the gradual improvement in gas exchange during cardiopulmonary resuscitation (CPR) and serving as a dynamic monitoring indicator of resuscitation effectiveness. Simultaneously, a distinct high-frequency sawtooth waveform is superimposed on the periodic pressure fluctuations of mechanical ventilation. This high-frequency sawtooth wave is caused by chest compressions; the instantaneous changes in intrathoracic pressure during compressions result in synchronous high-frequency, small-amplitude fluctuations in airway pressure. The frequency of this sawtooth wave is consistent with the compression frequency, directly reflecting the rhythm and intensity of chest compressions.

[0112] The real-time display of the aforementioned multi-parameter waveforms enables simultaneous monitoring of the ventilation and chest compression processes. In particular, the appearance of high-frequency sawtooth waves serves as an objective indicator of effective chest compressions, providing data support for quality control and parameter optimization during cardiopulmonary resuscitation.

[0113] In one embodiment, such as Figure 11 As shown, the cardiopulmonary resuscitation device also includes:

[0114] The communication module connects to the control module, ventilator, and compression device, respectively.

[0115] Specifically, the communication module is used to realize information interaction between the ventilator and the compression machine, and the control module is used to implement the control method mentioned above, which will not be elaborated here. The control module includes a finite state automaton (FSM) logic module, which is used to track the current state (compression in progress / compression completed / ventilation in progress / ventilation completed), and determine whether to allow the next action to be started based on the state decision tree, so as to realize true "interlocking and delocking" control. The state machine can be embedded in the ventilator main control chip or implemented through an external MCU module.

[0116] It should be noted that the finite state automaton includes the following state set: {S1: Pressing in progress, S2: Pressing complete, S3: Ventilation in progress, S4: Ventilation complete}. Its state transitions depend on the following trigger events received by the control module: E1 (Pressing complete), E2 (Ventilation complete), E3 (Ventilation started successfully), and E4 (Pressing started successfully).

[0117] State transitions satisfy the following rules, such as Figure 12 As shown:

[0118] S1→S2: Occurs only when a "Press Complete" signal (E1) is received and the current state is non-ventilated;

[0119] S2→S3: Occurs only when ventilation trigger permission is received and the interlock check passes;

[0120] S3→S4: Occurs when the ventilation time ends or when the "ventilation complete" flag (E2) is received;

[0121] S4→S1: Allow entry into the next press cycle.

[0122] Each transfer is only performed after the interlock condition check has passed, ensuring that compression and ventilation actions are strictly interlocked during CPR.

[0123] Among them, the interlocked state machine (finite state automaton) determines the allowed next action based on the current state, effectively preventing operational conflicts and ensuring efficient and safe CPR. Figure 12As shown, it includes four core states and six state transition paths. All transitions must satisfy interlocking conditions to form a closed-loop state sequence. Each state transition corresponds to a decision logic and a feedback flag. The state machine table can be directly called in the chip control logic for jump control. That is, the control module always maintains the compression and ventilation state variables. When compression is detected to be in progress or incomplete, ventilation is not allowed to be triggered. If ventilation is in progress, the next compression is not allowed to be started. This effectively avoids the problem of high airway pressure injury that is prone to occur when ventilation and compression operations conflict, and improves the success rate of cardiopulmonary resuscitation. At the same time, by applying the above-mentioned "interlocking parallel" mechanism, it makes up for the shortcomings of the existing asynchronous triggering mechanism in terms of accuracy and safety. It has high adaptability and industrialization prospects and is suitable for embedding into the next generation of emergency respiratory platforms (cardiopulmonary resuscitation devices).

[0124] For example, the cardiopulmonary resuscitation device also includes a user interface module for displaying the current number of compressions, ventilation status, peak pressure, alarm prompts, and rhythmic graphical guidance information to assist the operator in process monitoring and rhythm calibration, and is particularly suitable for real-time feedback in simulated teaching and training scenarios.

[0125] In one embodiment, the communication module connects to the ventilator and the compression device respectively via Bluetooth communication protocol.

[0126] Specifically, the communication module can be a Bluetooth communication module, preferably using the BLE (Bluetooth Low Energy) 5.0 protocol. Based on the characteristics of low power consumption, high speed and low latency wireless communication, it adopts a data frame structure with timestamps and status markers, and has frame verification and handshake retransmission mechanisms to achieve highly reliable synchronous signal transmission, which is superior to traditional cable / serial port protocols and facilitates clinical deployment and independent control of equipment.

[0127] It should be noted that ventilation commands, compression commands, and delay commands can all be transmitted via Bluetooth with low latency and marked with timestamps and compression numbers to ensure that the ventilator's ventilation rhythm and the compression machine maintain a 10:1 consistency; communication data format example: [Frame ID][Compression Number][Status Flag][Timestamp].

[0128] The Frame ID identifies the data frame type, the compression number distinguishes the current compression cycle, the status flag indicates the current device status (e.g., compression in progress, ventilation complete), and the timestamp records the precise moment the command is issued or the event occurs. Through this data structure and communication protocol, precise synchronization and interlocking control between the ventilator and the compression device can be achieved.

[0129] In this embodiment, the Bluetooth connection and interlock control mechanism ensure that compression and ventilation actions are completely decoupled but logically coordinated at the physical and control levels, achieving a "non-interference parallel" control effect. This effectively avoids the problem of high airway pressure injury that is prone to occur when ventilation and compression operations conflict, and improves the success rate of cardiopulmonary resuscitation.

[0130] In one embodiment, the communication module is connected to the ventilator and the pump via WIFI communication, CAN bus communication, and Zigbee communication, respectively.

[0131] Specifically, the communication module also supports WIFI communication protocol, CAN bus communication or Zigbee communication to achieve multi-mode data synchronization connection.

[0132] In one exemplary embodiment, a computer device is provided, which may be a terminal, and its internal structure diagram may be as follows: Figure 13 As shown. The computer device can be a terminal device, including but not limited to a portable cardiopulmonary resuscitation (CPR) host, a smart mobile device, or an embedded control terminal. The device includes a processor, memory, input / output interfaces, a communication interface, a display unit, and an input device. The processor, memory, and input / output interfaces are connected via a system bus, and the communication interface, display unit, and input device are connected to the system bus via the input / output interfaces. The processor of the computer device provides computing and control capabilities. The memory of the computer device includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage media. The input / output interfaces of the computer device are used for exchanging information between the processor and external devices. The communication interface of the computer device is used for wired or wireless communication with external terminals; wireless communication can be achieved through Wi-Fi, mobile cellular networks, Near Field Communication (NFC), or other technologies. When the computer program is executed by the processor, it implements a control method for a CPR device. The display unit of the computer device is used to form a visually visible image and can be a display screen, a projection device, or a virtual reality imaging device. The display screen can be an LCD screen or an e-ink screen. The input device of the computer device can be a touch layer covering the display screen, or buttons, trackballs, or touchpads set on the casing of the computer device, or external keyboards, touchpads, or mice, etc.

[0133] Those skilled in the art will understand that Figure 13The structures shown are merely block diagrams of some structures related to the present application and do not constitute a limitation on the computer device to which the present application is applied. In specific implementations, the computer device may include more or fewer components than shown in the figures, or combine certain components, or have different component arrangements.

[0134] In one exemplary embodiment, a computer device is provided, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the control method of the cardiopulmonary resuscitation device described above.

[0135] In one embodiment, a computer-readable storage medium is provided having a computer program stored thereon, which, when executed by a processor, implements the control method of the cardiopulmonary resuscitation device described above.

[0136] In one embodiment, a computer program product is provided, including a computer program that, when executed by a processor, implements the control method of the cardiopulmonary resuscitation device described above.

[0137] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, data stored, data displayed, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of the relevant data must comply with relevant regulations.

[0138] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile memory and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM). The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, artificial intelligence (AI) processors, etc., and are not limited to these.

[0139] It should be noted that the technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this application.

[0140] The embodiments described above are merely illustrative of several specific implementations of this application, and while the descriptions are detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these modifications and improvements all fall within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the appended claims.

Claims

1. A control method for a cardiopulmonary resuscitation device, characterized in that, The method is applied to a control module in a cardiopulmonary resuscitation (CPR) device, the CPR device including the control module, and a ventilator and a chest compression device respectively connected to the control module; the method includes: A pressing command is output to the pressing machine, and the number of times the pressing command is output is recorded; wherein, the pressing command is used to instruct the pressing machine to press; When the number of outputs reaches a preset value, a delay command is output to the presser and a ventilation command is output to the ventilator. The delay command instructs the presser to maintain the pressing state for a first duration, and the ventilation command controls the ventilator to trigger ventilation for a second duration, wherein the first duration is greater than or equal to the second duration. The ventilation command also instructs the ventilator to perform ventilation at an exponentially decreasing gas flow rate. If it is determined that the ventilator has completed the execution of the ventilation command and the compression device has completed the execution of the delay command, the output count is cleared to zero, and the execution of the compression command is returned to the compression device, and the output count of the compression command is recorded.

2. The method according to claim 1, characterized in that, The ventilator is equipped with an airway pressure sensor; the method further includes: The system receives pressure data from the airway pressure sensor. When the pressure data reaches a preset pressure threshold, it outputs a protection command to the ventilator and performs a protection operation. The protection command is used to instruct the ventilator to terminate the current ventilation action; the protection operation includes adjusting the ventilation parameters according to the pressure data, and the ventilation parameter adjustment includes at least one of adjusting the preset pressure threshold, adjusting the target tidal volume of the ventilator, and adjusting the gas flow rate of the ventilator.

3. The method according to claim 1, characterized in that, The gas flow velocity V(t) is shown in the following formula: V(t) = V0.e –kt ; Wherein, t is time in seconds; V0 is the initial flow velocity; and k is a decreasing coefficient, the value of which ranges from 0.5 to 1.5 s. -1 .

4. The method according to claim 1, characterized in that, The preset values ​​include 10, 15, and 30.

5. A control device for a cardiopulmonary resuscitation (CPR) device, characterized in that, The device is used in the control module of a cardiopulmonary resuscitation (CPR) device, which includes the control module and a ventilator and chest compression machine respectively connected to the control module; the device includes: The first output module is used to output a pressing command to the pressing machine and record the number of times the pressing command is output; wherein, the pressing command is used to instruct the pressing machine to press; The second output module is used to output a delay command to the presser and a ventilation command to the ventilator when the number of outputs reaches a preset value. The delay command instructs the presser to maintain the pressing state for a first duration, and the ventilation command instructs the ventilator to perform ventilation for a second duration, wherein the first duration is greater than or equal to the second duration. The ventilation command also instructs the ventilator to perform ventilation at an exponentially decreasing gas flow rate. The status judgment module is used to, when it is determined that the ventilator has completed the execution of the ventilation command and the presser has completed the execution of the delay command, clear the output count to zero, return to the presser to execute the presser, and record the output count of the presser command.

6. A cardiopulmonary resuscitation device, characterized in that, It includes a control module, and a ventilator and a compression device respectively connected to the control module; The control module is used to implement the steps of the method according to any one of claims 1 to 4.

7. The cardiopulmonary resuscitation device according to claim 6, characterized in that, The cardiopulmonary resuscitation device also includes: The communication module is connected to the control module, the ventilator, and the compression device, respectively.

8. The cardiopulmonary resuscitation device according to claim 7, characterized in that, The communication module connects to the ventilator and the compression device via Bluetooth communication protocol.

9. The cardiopulmonary resuscitation device according to claim 7, characterized in that, The communication module is connected to the ventilator and the pump via WIFI communication, CAN bus communication and Zigbee communication respectively.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 4.

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