Positive end-expiratory pressure measurement method and device based on pressure waveform and breathing machine

Abstract

The present application is suitable for the technical field of medical devices, and provides a positive end-expiratory pressure identification method and device based on pressure waveform and a breathing machine. The real-time pressure value of the breathing machine pipeline Y end is collected, the real-time pressure slope is obtained by derivation of the real-time pressure value with respect to time, whether the real-time pressure slope satisfies the preset condition of positive end-expiratory pressure value is judged, the pressure value when the preset condition is satisfied is obtained, and the positive end-expiratory pressure reference value in a breathing cycle is determined according to the priority of the preset condition, wherein the positive end-expiratory pressure reference value is the pressure value when the preset condition is satisfied. Finally, the positive end-expiratory pressure reference values in multiple breathing cycles are subjected to mean filtering to obtain the value of the positive end-expiratory pressure. The present application can accurately identify the positive end-expiratory pressure by reducing the interference of spontaneous breathing, so as to meet the accuracy requirement of the positive end-expiratory pressure reference value for the inspiratory pressure trigger, thereby avoiding the problem that the calculated positive end-expiratory pressure is sucked into the patient and collapses, resulting in the inability to identify the patient trigger.

Description

Technical Field

[0001] This invention belongs to the field of medical devices, and in particular relates to a method, device and ventilator for calculating end-expiratory positive pressure based on pressure waveform. Background Technology

[0002] In mechanical ventilation, we typically focus on three basic questions: when to start ventilation, how to deliver the air, and when to initiate exhalation. The timing of initiating ventilation is called triggering, and traditional triggering methods include time-triggered, pressure-triggered, and flow-triggered ventilation. Time-triggered ventilation involves the ventilator receiving a start-up command at a pre-set time point and initiating ventilation accordingly. Pressure-triggered and flow-triggered ventilation involve setting a trigger sensitivity before ventilation begins. When the pressure in the tubing drops to the set sensitivity, or the flow rate rises to the set sensitivity, the ventilator receives the ventilation command, controls the opening and closing of the inspiratory and expiratory valves, and begins ventilation. This brief process is called pressure-triggered or flow-triggered ventilation.

[0003] Positive End Expiratory Pressure (PEEP) is the baseline pressure maintained by a ventilator to keep the patient's lungs and chest cavity in a certain open state. Appropriate PEEP can open collapsed alveoli, making ventilation easier and improving ventilation efficiency. PEEP is also an important benchmark for calculating pressure drop values, especially in some ventilators that lack flow monitoring and only monitor pressure. These ventilators primarily use pressure-triggered delivery and cannot accurately control PEEP based on set values, or the ventilator adjusts PEEP via a circuit knob, making it impossible for the control unit to obtain the PEEP set value. In these cases, accurate PEEP measurement becomes even more crucial.

[0004] In existing technologies, the pressure value corresponding to 2 / 3 of the expiration time or the pressure value corresponding to the end of the expiration time is usually directly selected as the positive end-expiratory pressure (PEP). Both of these methods are greatly affected by spontaneous breathing. The first method, when the pressure drop waveform is relatively flat during the patient's expiration phase, is prone to misinterpreting the pressure drop before the pressure reaches a stable level during the expiration phase as pressure triggering, that is, identifying the PEP too early, resulting in misjudgment and trigger sensitivity, leading to incorrect delivery commands. The second method is prone to identifying the PEP value too low, making it difficult for the patient to inhale the set trigger sensitivity, thus failing to trigger the PEP.

[0005] Therefore, in ventilators with pure pressure monitoring, there is an urgent need for a method that can accurately identify positive end-expiratory pressure to meet the inspiratory pressure triggering conditions, in order to ensure that the ventilator delivers air and the patient’s spontaneous breathing are synchronized, and to avoid false triggering or difficulty in triggering. Summary of the Invention

[0006] This invention provides a method for calculating positive end-expiratory pressure based on pressure waveforms, aiming to solve the technical problem of false triggering or difficulty in triggering positive end-expiratory pressure of ventilators due to inaccurate identification.

[0007] To address the aforementioned technical problems, in a first aspect, embodiments of the present invention provide a method for calculating end-expiratory positive pressure based on pressure waveforms, comprising:

[0008] Collect the real-time pressure value at the Y end of the ventilator tubing;

[0009] The real-time pressure slope is obtained by differentiating the real-time pressure value with respect to time.

[0010] Determine whether the real-time pressure slope meets the preset conditions for taking the end-expiratory positive pressure value;

[0011] Obtain the pressure value that meets the preset conditions, and determine the positive end-expiratory pressure (PEAP) reference value within a respiratory cycle according to the priority of the preset conditions, wherein the PEAP reference value is the pressure value that meets the preset conditions;

[0012] The positive end-expiratory pressure (PEP) baseline values ​​within multiple respiratory cycles are averaged to obtain the PEP values.

[0013] Furthermore, the preset conditions for taking the end-expiratory positive pressure value include:

[0014] Preset condition 1: The absolute value of the real-time pressure slope is less than the set first threshold;

[0015] Preset condition 2: The absolute value of the real-time pressure slope is less than the first threshold, and after the absolute value of the real-time pressure slope is less than the first threshold, the real-time pressure slope is less than the second threshold.

[0016] Preset condition three: The absolute value of the real-time pressure slope is less than the set third threshold, and the duration for which the absolute value of the real-time pressure slope is less than the third threshold is greater than or equal to a preset value.

[0017] Furthermore, the step of obtaining the pressure value that satisfies the preset condition specifically includes:

[0018] If the first preset condition is met, then obtain the pressure value when the absolute value of the real-time pressure slope is less than the first threshold for the last occurrence before the end of exhalation.

[0019] Furthermore, the step of obtaining the pressure value that satisfies the preset condition specifically includes:

[0020] If the second preset condition is met, then when the real-time pressure slope is less than the second threshold for the first time, the pressure value at the first moment within the current time window is obtained.

[0021] Furthermore, the step of obtaining the pressure value that satisfies the preset condition specifically includes:

[0022] If the third preset condition is met, then the pressure value is obtained when the duration is equal to the preset value.

[0023] Furthermore, the priority of the preset conditions is that the priority of preset condition three is higher than the priority of preset condition two, and the priority of preset condition two is higher than the priority of preset condition one.

[0024] Furthermore, the method for calculating end-expiratory positive pressure based on pressure waveform also includes:

[0025] If none of the preset conditions are met, the pressure value during the transition from expiration to inhalation is used as the end-expiratory positive pressure reference value within a respiratory cycle.

[0026] Secondly, the present invention also provides a device for calculating end-expiratory positive pressure based on pressure waveform, comprising:

[0027] The real-time pressure acquisition unit is used to acquire the real-time pressure value at the Y end of the ventilator tubing;

[0028] The real-time pressure slope calculation unit is used to obtain the real-time pressure slope by differentiating the real-time pressure value with respect to time.

[0029] A preset condition judgment unit is used to determine whether the real-time pressure slope meets the preset conditions for taking the end-expiratory positive pressure value.

[0030] The positive end-expiratory pressure (PEP) reference value determination unit is used to obtain the pressure value when the preset conditions are met, and to determine the PEP reference value within a respiratory cycle according to the priority of the preset conditions, wherein the PEP reference value is the pressure value when the preset conditions are met.

[0031] The mean filtering unit is used to perform mean filtering on the positive end-expiratory pressure (PEP) reference values ​​within multiple respiratory cycles to obtain the PEP value.

[0032] Thirdly, the present invention also provides a ventilator, comprising:

[0033] The pressure sampling tube is used to collect the real-time pressure value at the Y end of the ventilator tubing;

[0034] One or more processors, working individually or collectively, are used to perform the following steps:

[0035] The real-time pressure slope is obtained by differentiating the real-time pressure value with respect to time.

[0036] Determine whether the real-time pressure slope meets the preset conditions for taking the end-expiratory positive pressure value;

[0037] Obtain the pressure value that meets the preset conditions, and determine the positive end-expiratory pressure (PEAP) reference value within a respiratory cycle according to the priority of the preset conditions, wherein the PEAP reference value is the pressure value that meets the preset conditions;

[0038] The positive end-expiratory pressure (PEP) baseline values ​​within multiple respiratory cycles are averaged to obtain the PEP values.

[0039] as well as

[0040] A memory used to store data.

[0041] Fourthly, the present invention also provides a computer-readable storage medium storing program instructions that, when executed by a processor, implement the steps of the end-expiratory positive pressure calculation method based on pressure waveform according to any one of claims 1 to 7.

[0042] This invention reduces the interference of spontaneous breathing by judging the real-time pressure slope based on preset conditions for obtaining the positive end-expiratory pressure (PEAP) value, determining the PEAP baseline value according to the priority of the preset conditions, and then performing mean filtering to obtain the PEAP value. This enables accurate identification of PEAP to meet the accuracy requirements of the PEAP baseline value for inspiratory pressure triggering, ensuring synchronization between ventilator delivery and the patient's spontaneous breathing, and avoiding problems of false triggering or difficulty in triggering. Attached Figure Description

[0043] To more clearly illustrate the solutions in this invention, the accompanying drawings used in the description of the embodiments of this invention will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0044] Figure 1 This is a flowchart of an embodiment of the end-tidal positive pressure calculation method based on pressure waveform provided by the present invention;

[0045] Figure 2 This is a schematic diagram of an embodiment of the preset conditions for end-tidal positive pressure provided by the present invention;

[0046] Figure 3 This is a schematic diagram of the end-expiratory positive pressure measurement device based on pressure waveform provided by the present invention;

[0047] Figure 4This is a schematic diagram of the structure of a ventilator provided by the present invention. Detailed Implementation

[0048] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains; the terminology used herein in the specification is for the purpose of describing particular embodiments only and is not intended to limit the invention; the terms "comprising" and "having," and any variations thereof, in the specification, claims, and foregoing drawings are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the specification, claims, or foregoing drawings are used to distinguish different objects and not to describe a particular order.

[0049] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0050] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0051] In mechanical ventilation, positive end-expiratory pressure (PEEP) is a crucial factor in ventilator pressure triggering. Generally, ventilators aiming to improve patient-ventilator interaction and reduce patient-ventilator asynchrony must have an inspiratory triggering function to synchronize ventilator-delivered air with the patient's spontaneous breathing. Some low-end ventilators only monitor pressure, not flow rate. Because they can only monitor pressure waveforms, the only way for such ventilators to trigger patient responses is through pressure triggering. However, the PEEP setting on these ventilators may rely on a circuit knob, preventing the machine from accurately acquiring the set PEEP value. When using pressure triggering, PEEP is a critical benchmark for determining when pressure drops below the set value to activate triggering. When the pressure falls below the set PEEP value, triggering is recognized.

[0052] When only a pure pressure waveform is available, in addition to using positive end-expiratory pressure (PEEP) as a reference to identify inspiratory pressure, another method to identify inspiratory trigger is through the slope of the pressure. For example, if the pressure drops to a certain value within a fixed time window, a sufficient slope will be generated to identify trigger. However, this is not suitable for patients taking slow, deep breaths, which may result in very low pressure being reached without triggering. Considering this situation, this invention proposes a method for calculating PEEP based on pressure waveform to meet the inspiratory pressure triggering conditions, thereby ensuring synchronization between ventilator delivery and the patient's spontaneous breathing, and avoiding false triggering or difficulty in triggering.

[0053] Example 1

[0054] Please see Figure 1 This invention provides a method for calculating end-expiratory positive pressure based on pressure waveforms, comprising:

[0055] In step S1, the real-time pressure value at the Y end of the ventilator tubing is collected;

[0056] It is understood that, in the embodiments of the present invention, during breathing using a mechanical ventilation device, there is an inspiratory valve in the inspiratory tubing and an expiratory valve in the expiratory tubing. Both tubings are connected to the patient via a ventilator tubing, which is typically a Y-shaped tubing; therefore, the end of the tubing connected to the patient is usually referred to as the Y-end of the tubing. At the end of expiration, when both the inspiratory and expiratory valves are closed, the tubing becomes a sealed container. When the patient inhales, the pressure inside the tubing decreases. When the pressure drops to the set trigger sensitivity, the ventilator receives a ventilation command, opens the inspiratory valve, and begins delivering air. This brief process is called pressure triggering.

[0057] In some implementations, the ventilator is equipped with a pressure sampling tube at the Y-end of the tubing. This tube allows for real-time acquisition of the pressure value at the Y-end of the ventilator tubing. The real-time pressure can be acquired via the pressure sampling tube or other sensors capable of obtaining real-time pressure values; no limitation is made here.

[0058] In step S2, the real-time pressure slope is obtained by differentiating the real-time pressure value with respect to time.

[0059] It is understood that, in the embodiments of the present invention, there are many ways to differentiate the real-time pressure value with respect to time. The real-time pressure slope can be obtained by linear fitting, low-pass filtering, Kalman filtering, or other differentiation methods in digital signal processing. No limitation is made here.

[0060] It is understood that, in the embodiments of the present invention, for example, by means of linear fitting, a time window of a time period such as 50ms can be preset, the time period corresponding to 10 real-time pressure value points is selected as a 50ms time window, the 10 real-time pressure value points within the 50ms time window are linearly fitted by a linear function, and then the real-time pressure slope is obtained by taking the derivative with respect to time.

[0061] In other implementations, the parameters of the linear function can be obtained by using fast least squares, approximating discrete data with analytical expressions, or other linear function fitting methods. The real-time pressure slope is a parameter that represents how fast the real-time pressure value changes over time.

[0062] Understandably, in some implementations, by fitting a linear function to points such as 10 real-time pressure values ​​within a preset time window using the least squares method, the resulting slope value is assumed to be the slope corresponding to the median of these 10 points. As the time window slides, the pressure slope that changes over time can be obtained. The pressure slope obtained by fitting a linear function within each time window is called the real-time pressure slope.

[0063] In step S3, it is determined whether the real-time pressure slope meets the preset conditions for taking the end-expiratory positive pressure value;

[0064] Understandably, in some implementations, after obtaining a real-time pressure slope with a certain noise resistance, the expiratory time set in the machine-controlled breathing is obtained, such as 3 to 5 seconds. After waiting for 2 / 3 of the expiratory time to arrive, the real-time pressure slope is then judged to meet the preset conditions for the positive end-expiratory pressure value. That is, the pressure is assumed to have dropped after 2 / 3 of the expiratory time before triggering is allowed, to prevent the pressure value from dropping under machine-controlled pressure and being mistakenly judged as the patient inhaling.

[0065] Understandably, in specific implementation, the preset condition for obtaining the end-expiratory positive pressure value is that this invention judges the pressure change during the expiratory phase based on the changes in the real-time pressure slope. For example, when the real-time pressure slope meets certain conditions, it reflects the existence of a pressure stability region with a relatively long duration. When the real-time pressure slope meets certain conditions, a sudden drop in pressure value will occur in a short period of time. Thus, the change in the real-time pressure slope can be used to identify when the patient reaches the stability phase at the end of expiration. Finally, the value of the end-expiratory stable pressure is used as the benchmark value for pressure triggering.

[0066] It is understandable that there may be one or more preset conditions for obtaining the positive end-expiratory pressure (PEP) value. Under different preset conditions, different methods are used to obtain the PEP value. The method of obtaining the PEP value can be direct assignment or calculation, and there is no limitation here.

[0067] In step S4, the pressure value that meets the preset conditions is obtained, and the positive end-expiratory pressure (PEAP) reference value within a respiratory cycle is determined according to the priority of the preset conditions, wherein the PEAP reference value is the pressure value that meets the preset conditions.

[0068] Specifically, in this embodiment, the pressure value obtained when the preset conditions are met is determined by different methods for obtaining the pressure value according to different preset conditions. When there are multiple preset conditions, a priority can be set. The preset conditions can be judged according to the priority, or the pressure value can be obtained simultaneously according to multiple different preset conditions. Finally, the value is obtained according to the priority of the preset conditions.

[0069] Specifically, in some possible embodiments, for example, preset condition three is given higher priority than preset condition two. That is, it is first determined whether preset condition three is met. If it is met, the pressure value under preset condition three is obtained, and it is not necessary to determine whether preset condition two is met again. Unless preset condition three is not met, then it is determined whether preset condition two is met.

[0070] Specifically, in some other possible embodiments, for example, preset condition three and preset condition two are judged simultaneously, and the pressure value when preset condition three is met and the pressure value when preset condition two is met are obtained respectively. Since preset condition three has a higher priority than preset condition two, the pressure value when preset condition three is met is obtained as the final value, unless preset condition three is not met, in which case the pressure value when preset condition two is met is obtained as the final value.

[0071] Specifically, in this embodiment, the pressure changes periodically over time with the rhythm of breathing. The judgment and value of the preset conditions are within one respiratory cycle. Therefore, the pressure value obtained when the preset conditions are met is the end-expiratory positive pressure reference value within one respiratory cycle.

[0072] In step S5, the end-expiratory positive pressure baseline values ​​within multiple respiratory cycles are averaged and filtered to obtain the end-expiratory positive pressure value.

[0073] Specifically, in this embodiment, the positive end-expiratory pressure (PEEP) baseline value is obtained by acquiring multiple respiratory cycles, and the obtained PEEP baseline value is mean-filtered to obtain the final PEEP value used to achieve pressure triggering.

[0074] Specifically, in this embodiment, the positive end-expiratory pressure (PEAP) baseline value is averaged over multiple cycles, and the average value of the PEAP baseline value is used when triggering. In this way, even if the PEAP is misidentified in some cycles due to pressure fluctuations at the patient end, the stability of the triggering can still be guaranteed.

[0075] This invention relates to a method for calculating positive end-expiratory pressure (PEAP) based on pressure waveforms. It determines the PEAP baseline value by judging the real-time pressure slope according to preset conditions and prioritizing these conditions. Then, it performs mean filtering to obtain the PEAP value, thereby reducing the interference from spontaneous breathing. This method accurately identifies PEAP, meeting the accuracy requirements of the PEAP baseline value for inspiratory pressure triggering, ensuring trigger stability, and ensuring synchronization between ventilator delivery and the patient's spontaneous breathing. This effectively avoids problems such as false triggering or difficulty in triggering.

[0076] Example 2

[0077] Further, please refer to Figure 2 , Figure 2 This is a schematic diagram of a specific implementation of the preset conditions for obtaining end-expiratory positive pressure (PEP) values ​​provided by the present invention. The preset conditions for obtaining PEP values ​​in step S3 include:

[0078] In step S31, the first preset condition is: the absolute value of the real-time pressure slope is less than the set first threshold.

[0079] Specifically, in this embodiment, the absolute value of the real-time pressure slope is calculated based on the obtained real-time pressure slope. The absolute value of the real-time pressure slope is compared with a set first threshold. When the absolute value of the real-time pressure slope is less than the set first threshold, the real-time pressure slope meets the preset condition one, and the end-expiratory positive pressure value can be obtained according to the preset condition one.

[0080] Specifically, in this embodiment, the first threshold is set to 2K0, which is selected according to the actual situation of the ventilator. For example, depending on the ventilator, K0 can be set to 0.8 cmH2O / s, then the corresponding first threshold is 1.6 cmH2O / s; or K0 can be set to 1 cmH2O / s or 1.2 cmH2O / s, then the corresponding first threshold is 2 cmH2O / s or 2.4 cmH2O / s, depending on the actual situation of the respiratory rate or other parameters set by the ventilator.

[0081] In step S32, the second preset condition is: the absolute value of the real-time pressure slope is less than the first threshold, and after the absolute value of the real-time pressure slope is less than the first threshold, the real-time pressure slope is less than the second threshold.

[0082] In a specific embodiment, the absolute value of the real-time pressure slope is calculated based on the obtained real-time pressure slope. The absolute value of the real-time pressure slope is compared with a set first threshold. When the absolute value of the real-time pressure slope is less than the set first threshold, the real-time pressure slope is continued to be obtained. It is then determined whether the real-time pressure slope will be less than a second threshold after the absolute value of the real-time pressure slope is less than the first threshold. If it is, the real-time pressure slope meets the second preset condition, and the end-expiratory positive pressure value can be obtained according to the second preset condition.

[0083] Specifically, in this embodiment, the second threshold is set to -8K0. For example, if K0 is set to 1cmH2O / s, the corresponding second threshold is -8cmH2O / s. Alternatively, K0 can be set to 0.8cmH2O / s, in which case the corresponding second threshold is -6.4cmH2O / s. The specific choice depends on the actual situation of the respiratory rate or other parameters set by the ventilator.

[0084] In step S33, the third preset condition is: the absolute value of the real-time pressure slope is less than the set third threshold, and the duration for which the absolute value of the real-time pressure slope is less than the third threshold is greater than or equal to a preset value.

[0085] In a specific embodiment, the absolute value of the real-time pressure slope is calculated based on the obtained real-time pressure slope. The absolute value of the real-time pressure slope is compared with a set third threshold. When the absolute value of the real-time pressure slope is less than the set third threshold, the real-time pressure slope is continued to be obtained. It is then determined whether, after the absolute value of the real-time pressure slope is less than the first threshold, the duration of the absolute value of the real-time pressure slope being less than the third threshold is greater than or equal to a preset value. If this occurs, the real-time pressure slope meets the preset condition three, and the end-expiratory positive pressure value can be obtained according to the preset condition three.

[0086] Specifically, in this embodiment, the third threshold is set to K0. For example, K0 can be set to 1 cmH2O / s, 0.8 cmH2O / s, or 1.2 cmH2O / s, depending on the actual situation of the respiratory rate or other parameters set by the ventilator.

[0087] Specifically, in this embodiment, the preset value of the duration is to determine whether there is a region with a stable pressure value. Therefore, using a certain amount of time as the preset value of the duration can ensure that the pressure value that reaches a certain duration is the band where the positive end-expiratory pressure is maintained.

[0088] Specifically, in this embodiment, Figure 2 This is for illustrative purposes only and does not represent the order in which the judgments are made among the various preset conditions. Therefore, the illustrative diagram does not impose any limitations. In fact, the controller can make conditional judgments on the pressure slope simultaneously.

[0089] Specifically, in some implementations, the priority of the preset conditions is that preset condition three has a higher priority than preset condition two, and preset condition two has a higher priority than preset condition one. That is, after obtaining the real-time pressure slope, multiple different preset conditions are judged simultaneously, and the pressure value when preset condition one is met, the pressure value when preset condition two is met, and the pressure value when preset condition three is met are obtained respectively. The pressure value when preset condition three is met is taken as the final value. If preset condition three is not met, the pressure value when preset condition two is met is taken as the final value. If preset condition two is not met, the pressure value when preset condition one is met is taken as the final value.

[0090] By setting different preset conditions, pressure value changes under different conditions can be covered. Since waveform changes under different conditions may affect the recognition of pressure triggering, different preset conditions are set to ensure the accuracy of end-expiratory positive pressure values ​​under different conditions, thereby improving the anti-interference ability and reliability of pressure triggering during inspiration.

[0091] Example 3

[0092] Furthermore, the step of obtaining the pressure value when the preset condition is met based on the judgment result of the present invention is as follows: if the preset condition one is met, then obtain the pressure value when the absolute value of the last real-time pressure slope before the end of exhalation is less than the first threshold.

[0093] Specifically, in this embodiment, if the absolute value of the real-time pressure slope is less than the set 2K0, then the pressure value at the last time the absolute value of the real-time pressure slope is less than 2K0 before the end of exhalation is obtained.

[0094] Specifically, in this embodiment, the time for the end of exhalation can be a time set by the ventilator, such as 3-5 seconds, or it can be a time period from the point when the inhalation phase transitions to exhalation to the point when the trigger is successfully identified as the exhalation time.

[0095] Specifically, in this embodiment, after the absolute value of the real-time pressure slope is less than 2K0, the real-time pressure slope is continuously acquired, and it is continuously determined whether the absolute value of the acquired real-time pressure slope is less than 2K0 again. If the condition is met for the second time, the pressure value acquired when the condition is met for the second time is overwritten with the pressure value stored when the condition is met for the first time. When it is determined that the absolute value of the real-time pressure slope is less than 2K0 when the condition is met for the third time, the pressure value acquired when the condition is met for the third time is overwritten with the pressure value stored when the condition is met for the second time. And so on, until the pressure value is acquired when the absolute value of the real-time pressure slope is less than 2K0 for the last time before the end of exhalation.

[0096] By setting a preset condition, if the absolute value of the last real-time pressure slope before the end of expiration is less than the first threshold, the pressure value is obtained. This is mainly because, based on the ventilator settings and the patient's actual situation, when the pressure slope is relatively gentle, this method of obtaining the pressure value can basically ensure the reliability of the obtained positive end-expiratory pressure, thereby ensuring the stability of pressure triggering.

[0097] Example 4

[0098] Furthermore, the step of obtaining the pressure value when the preset condition is met based on the judgment result of the present invention is as follows: if the second preset condition is met, then when the real-time pressure slope is less than the second threshold for the first time, the pressure value at the first time point within the current time window is obtained.

[0099] Specifically, in this embodiment, if the absolute value of the real-time pressure slope is less than 2K0, and after the absolute value of the real-time pressure slope is less than 2K0, the real-time pressure slope becomes less than -8K0, then when the real-time pressure slope becomes less than -8K0 for the first time, the pressure value at the first moment within the current time window is obtained.

[0100] Specifically, in this embodiment, the time window is a time period with a preset length of 50ms. Ten time points are set within the 50ms time window. As the time window slides, the pressure slope that changes over time can be obtained. The pressure slope within any 50ms time window is the slope corresponding to the median value of the 10 time points within the time window. When the real-time pressure slope is less than -8K0 for the first time, the pressure value of the first time point within the current time window is obtained.

[0101] By setting a preset condition two, when the real-time pressure slope first falls below the second threshold, the pressure value at the first moment of the time window is obtained. Since this condition applies after a relatively stable pressure level, where the pressure drops rapidly due to strong spontaneous breathing, the pressure before this drop can be used as the positive end-expiratory pressure (PEAP). This requires the patient to inhale with a certain intensity, allowing the pressure slope to clearly identify the interval where spontaneous breathing begins. The pressure before spontaneous breathing is then marked as PEAP, and obtaining the pressure value at the first moment of the time window ensures more accurate pressure triggering, preventing false triggering or failure to trigger.

[0102] Example 5

[0103] Furthermore, the step of obtaining the pressure value when the preset condition is met based on the judgment result of the present invention is specifically as follows: if preset condition three is met, then obtain the pressure value when the duration is equal to the preset value.

[0104] Specifically, in this embodiment, if the absolute value of the real-time pressure slope is less than K0, and the duration of the absolute value of the real-time pressure slope being less than K0 is greater than or equal to a preset value, then the pressure value when the duration is equal to the preset value is obtained.

[0105] Specifically, in this embodiment, the third threshold is set to K0. For example, K0 can be set to 1 cmH2O / s, 0.8 cmH2O / s, or 1.2 cmH2O / s, depending on the actual situation of the respiratory rate or other parameters set by the ventilator.

[0106] Specifically, in this embodiment, the preset value of the duration is to determine whether there is a region with a stable pressure value. Therefore, using a certain amount of time as the preset value of the duration can ensure that the pressure value that reaches a certain duration is the band where the positive end-expiratory pressure is maintained.

[0107] By setting a preset condition three, the pressure value is obtained when the duration equals a preset value. Since the pressure can maintain a small fluctuation range within a certain period of time during the exhalation phase, it is considered that the period is in the stable phase of exhalation. Therefore, obtaining the pressure value during this time period as the end-expiratory positive pressure baseline value can further ensure the accuracy of pressure triggering.

[0108] Example 6

[0109] Another specific embodiment of the end-expiratory positive pressure calculation method based on pressure waveform provided by the present invention further includes:

[0110] If none of the preset conditions are met, the pressure value during the transition from expiration to inspiration will be used as the baseline value for positive end-expiratory pressure within a respiratory cycle.

[0111] Specifically, in this embodiment, the main difference from Embodiment 1 lies in the following: Figure 1 In step S4, if the preset conditions for the real-time pressure slope to take the end-expiratory positive pressure value are not met, the pressure value at the time of the transition from expiration to inspiration is directly obtained as a reference value for the end-expiratory positive pressure within a respiratory cycle. For example, the pressure at the time of the transition from expiration to inspiration can be the pressure value corresponding to 90% or 95% of the expiration time, or it can be other proportional coefficients within the range of [90%, 95%].

[0112] Specifically, in some embodiments, the exhalation time can be a time set on the ventilator or the actual exhalation time, where the actual exhalation time refers to a time value between the start of exhalation and the successful recognition of pressure triggering.

[0113] This condition applies when there are abnormal pressure slope issues. The ventilator can still provide a value for positive end-expiratory pressure (PEEP) for pressure trigger identification. In addition, since the minimum PEEP is set to 3, a protection pressure can be set. For example, if the airway pressure reaches -1 cmH2O, then regardless of the PEEP value, it should be triggered.

[0114] Example 7

[0115] Please see Figure 3 , Figure 3 This is a schematic diagram of the end-tidal positive pressure measurement device based on pressure waveform provided by the present invention, as a reference. Figure 1 The implementation of the end-expiratory positive pressure (PEP) calculation method based on pressure waveform is shown in this embodiment. This embodiment provides a device for calculating PEP based on pressure waveform, and the device embodiment is similar to... Figure 1 Corresponding to the method embodiment shown, the apparatus includes:

[0116] The real-time pressure acquisition unit 21 is used to acquire the real-time pressure value at the Y end of the ventilator tubing;

[0117] The real-time pressure slope calculation unit 22 is used to obtain the real-time pressure slope by differentiating the real-time pressure value with respect to time.

[0118] The preset condition judgment unit 23 is used to determine whether the real-time pressure slope meets the preset conditions for taking the end-expiratory positive pressure value.

[0119] The positive end-expiratory pressure (PEP) reference value determination unit 24 is used to obtain the pressure value when the preset conditions are met, and to determine the PEP reference value within a respiratory cycle according to the priority of the preset conditions, wherein the PEP reference value is the pressure value when the preset conditions are met.

[0120] The mean filtering unit 25 is used to perform mean filtering on the end-expiratory positive pressure baseline values ​​within multiple respiratory cycles to obtain the end-expiratory positive pressure value.

[0121] The beneficial effect of the positive end-expiratory pressure (PEAP) measuring device 20 based on pressure waveform in this embodiment of the invention is that by setting different preset conditions, it can cover the changes in pressure values ​​under different conditions. Since waveform changes under different conditions may affect the identification of pressure triggering, different preset conditions are set to ensure the accuracy of PEAP values ​​under different conditions, thereby improving the anti-interference ability and reliability of pressure triggering during inhalation.

[0122] Example 8

[0123] Please see Figure 4 This invention also provides a ventilator 10, which includes:

[0124] Pressure sampling tube 11 is used to collect the real-time pressure value at the Y end of the ventilator tubing;

[0125] One or more processors 12, working individually or collectively, are used to perform the following steps:

[0126] The real-time pressure slope is obtained by differentiating the real-time pressure value with respect to time.

[0127] Determine whether the real-time pressure slope meets the preset conditions for taking the end-expiratory positive pressure value;

[0128] Obtain the pressure value that meets the preset conditions, and determine the positive end-expiratory pressure (PEAP) reference value within a respiratory cycle according to the priority of the preset conditions, wherein the PEAP reference value is the pressure value that meets the preset conditions;

[0129] The positive end-expiratory pressure (PEP) baseline values ​​within multiple respiratory cycles are averaged to obtain the PEP values.

[0130] as well as

[0131] Memory 13 is used to store data.

[0132] Specifically, in this embodiment, the processor 12 may be a central processing unit (CPU), controller, microcontroller, microprocessor, or other data processing chip in some embodiments. The processor 12 is typically used to control the overall operation of the ventilator.

[0133] In this embodiment, the processor 12 is used to run computer-readable instructions or process data stored in the memory 13, such as running computer-readable instructions for a ventilator-based method for calculating end-expiratory positive pressure based on pressure waveforms.

[0134] Those skilled in the art will understand that the memory 13 includes at least one type of readable storage medium, including flash memory, hard disk, multimedia card, card-type memory (e.g., SD or DX memory), random access memory (RAM), static random access memory (SRAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), programmable read-only memory (PROM), magnetic memory, disk, optical disk, etc.

[0135] In some embodiments, memory 13 may be an internal storage unit of the ventilator, such as the hard disk or memory of the ventilator.

[0136] In other embodiments, the memory 13 may also be an external storage device of the ventilator, such as a plug-in hard drive, smart media card (SMC), secure digital (SD) card, flash card, etc.

[0137] Of course, the memory 13 may include both the internal storage unit of the ventilator and its external storage device.

[0138] The beneficial effect of the ventilator 10 in this embodiment of the invention is that by setting different preset conditions, it can cover the changes in pressure values ​​under different conditions. The waveform changes under different conditions may affect the identification of pressure triggering. Therefore, setting different preset conditions can ensure the accuracy of end-expiratory positive pressure values ​​under different conditions, thereby improving the anti-interference ability and reliability of pressure triggering during inspiration.

[0139] Example 8

[0140] This invention also provides a storage medium storing program instructions for executing the above-described method for calculating end-tidal positive pressure based on pressure waveforms.

[0141] The beneficial effect of the storage medium of the present invention is that by setting different preset conditions, it can cover the changes in pressure values ​​under different conditions. Since waveform changes under different conditions may affect the identification of pressure triggering, different preset conditions are set to ensure the accuracy of end-expiratory positive pressure values ​​under different conditions, thereby improving the anti-interference ability and reliability of pressure triggering during inhalation.

[0142] This invention can be used in a wide range of general-purpose or special-purpose computer system environments or configurations.

[0143] Examples include: personal computers, server computers, handheld or portable devices, tablet devices, multiprocessor systems, microprocessor-based systems, set-top boxes, programmable consumer electronics, network PCs, minicomputers, mainframe computers, and distributed computing environments that include any of the above systems or devices.

[0144] The method of this invention involves acquiring real-time pressure values ​​at the Y-end of the ventilator tubing, performing linear function fitting on the real-time pressure values ​​within a set time window to obtain the real-time pressure slope, determining whether the real-time pressure slope meets preset conditions for PEEP (Positive End-Expiratory Pressure) values, obtaining the pressure value that meets the preset conditions, and determining the PEEP baseline value for a respiratory cycle based on the priority of the preset conditions. The PEEP baseline value is the pressure value that meets the preset conditions. Finally, the PEEP baseline values ​​over multiple respiratory cycles are averaged and filtered to obtain the PEEP value. Therefore, by setting different preset conditions, pressure value changes under different conditions can be covered. Furthermore, different preset conditions are set to ensure the accuracy of PEEP values ​​under different conditions, addressing the potential impact of waveform changes on pressure trigger identification. This satisfies the accuracy requirements of inspiratory pressure triggering for the PEEP baseline value, ensuring synchronization between ventilator delivery and the patient's spontaneous breathing, thereby avoiding false triggering or difficulty in triggering, and improving the anti-interference capability and reliability of inspiratory pressure triggering.

[0145] It is understood that those skilled in the art can combine various implementation methods in the above embodiments under the guidance of the above examples to obtain technical solutions with multiple implementation methods.

[0146] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for calculating end-expiratory positive pressure based on pressure waveform, characterized in that, include: Collect the real-time pressure value at the Y end of the ventilator tubing; The real-time pressure slope is obtained by differentiating the real-time pressure value with respect to time. Determine whether the real-time pressure slope meets the preset conditions for taking the end-expiratory positive pressure value; Obtain the pressure value that meets the preset conditions, and determine the positive end-expiratory pressure (PEAP) reference value within a respiratory cycle according to the priority of the preset conditions, wherein the PEAP reference value is the pressure value that meets the preset conditions; The positive end-expiratory pressure (PEP) baseline values ​​within multiple respiratory cycles are averaged to obtain the PEP values. The preset conditions for taking the end-tidal positive pressure value include: Preset condition 1: The absolute value of the real-time pressure slope is less than the set first threshold; Preset condition 2: The absolute value of the real-time pressure slope is less than the first threshold, and after the absolute value of the real-time pressure slope is less than the first threshold, the real-time pressure slope is less than the second threshold. Preset condition three: The absolute value of the real-time pressure slope is less than the set third threshold, and the duration for which the absolute value of the real-time pressure slope is less than the third threshold is greater than or equal to a preset value.

2. The method for calculating end-expiratory positive pressure based on pressure waveform as described in claim 1, characterized in that, The step of obtaining the pressure value when the preset condition is met specifically includes: If the first preset condition is met, then obtain the pressure value when the absolute value of the real-time pressure slope is less than the first threshold for the last occurrence before the end of exhalation.

3. The method for calculating end-expiratory positive pressure based on pressure waveform as described in claim 1, characterized in that, The step of obtaining the pressure value when the preset condition is met specifically includes: If the second preset condition is met, then when the real-time pressure slope is less than the second threshold for the first time, the pressure value at the first moment within the current time window is obtained.

4. The method for calculating end-expiratory positive pressure based on pressure waveform as described in claim 1, characterized in that, The step of obtaining the pressure value when the preset condition is met specifically includes: If the third preset condition is met, then the pressure value is obtained when the duration is equal to the preset value.

5. The method for calculating end-expiratory positive pressure based on pressure waveform as described in any one of claims 1 to 4, characterized in that, The priority of the preset conditions is as follows: the priority of preset condition three is higher than the priority of preset condition two, and the priority of preset condition two is higher than the priority of preset condition one.

6. The method for calculating end-expiratory positive pressure based on pressure waveform as described in claim 1, characterized in that, The method further includes: If none of the preset conditions are met, the pressure value during the transition from expiration to inhalation is used as the end-expiratory positive pressure reference value within a respiratory cycle.

7. A device for calculating end-expiratory positive pressure based on pressure waveform, characterized in that, include: The real-time pressure acquisition unit is used to acquire the real-time pressure value at the Y end of the ventilator tubing; The real-time pressure slope calculation unit is used to obtain the real-time pressure slope by differentiating the real-time pressure value with respect to time. A preset condition judgment unit is used to determine whether the real-time pressure slope meets the preset conditions for taking the end-expiratory positive pressure value. The positive end-expiratory pressure (PEP) reference value determination unit is used to obtain the pressure value when the preset conditions are met, and to determine the PEP reference value within a respiratory cycle according to the priority of the preset conditions, wherein the PEP reference value is the pressure value when the preset conditions are met. The mean filtering unit is used to perform mean filtering on the positive end-expiratory pressure (PEP) reference values ​​within multiple respiratory cycles to obtain the PEP value. The preset conditions for taking the end-tidal positive pressure value include: Preset condition 1: The absolute value of the real-time pressure slope is less than the set first threshold; Preset condition 2: The absolute value of the real-time pressure slope is less than the first threshold, and after the absolute value of the real-time pressure slope is less than the first threshold, the real-time pressure slope is less than the second threshold. Preset condition three: The absolute value of the real-time pressure slope is less than the set third threshold, and the duration for which the absolute value of the real-time pressure slope is less than the third threshold is greater than or equal to a preset value.

8. A ventilator, characterized in that, include: The pressure sampling tube is used to collect the real-time pressure value at the Y end of the ventilator tubing; One or more processors, working individually or collectively, are used to perform the following steps: The real-time pressure slope is obtained by differentiating the real-time pressure value with respect to time. Determine whether the real-time pressure slope meets the preset conditions for taking the end-expiratory positive pressure value; Obtain the pressure value that meets the preset conditions, and determine the positive end-expiratory pressure (PEAP) reference value within a respiratory cycle according to the priority of the preset conditions, wherein the PEAP reference value is the pressure value that meets the preset conditions; The positive end-expiratory pressure (PEP) baseline values ​​within multiple respiratory cycles are averaged to obtain the PEP values. as well as A memory used to store data; The preset conditions for taking the end-tidal positive pressure value include: Preset condition 1: The absolute value of the real-time pressure slope is less than the set first threshold; Preset condition 2: The absolute value of the real-time pressure slope is less than the first threshold, and after the absolute value of the real-time pressure slope is less than the first threshold, the real-time pressure slope is less than the second threshold. Preset condition three: The absolute value of the real-time pressure slope is less than the set third threshold, and the duration for which the absolute value of the real-time pressure slope is less than the third threshold is greater than or equal to a preset value.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores program instructions that, when executed by a processor, implement the steps of the end-tidal positive pressure calculation method based on pressure waveforms according to any one of claims 1 to 6.

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