A method for simulating a different-synchronization waveform between a human and a machine

Abstract

The application provides a method for simulating human-machine asynchronization waveform, and the method is characterized in that: a coupling mathematical model of a human respiratory system and a breathing machine is established, a working mode of a clinical breathing machine, i.e., volume control and pressure control, is simulated, and the human-machine asynchronization waveform is simulated and generated. The human respiratory system model structure in the mathematical model established by the application is consistent with the real human structure, and the control strategy of the breathing machine model is reasonable and effective, so that the model is effective and has interpretability. The application can improve the problem that it is difficult to obtain the human-machine asynchronization breathing waveform data with labels. The application provides a new means and angle for the research on the medical phenomenon of human-machine asynchronization.

Description

Technical Field

[0001] This invention relates to a method for simulating and generating asynchronous waveforms between humans and machines. It belongs to the field of simulating medical physiological signal generation. Background Technology

[0002] For patients unable to breathe spontaneously, mechanical ventilation is a crucial life support measure. During mechanical ventilation, asynchrony occurs when the patient's and ventilator's inspiratory and expiratory times are mismatched. This asynchrony leads to decreased patient comfort, prolonged mechanical ventilation time, difficulty in extubation, increased risk of lung injury, and even increased risk of death. With the development and refinement of deep learning theory, neural networks are widely used in the medical field, including the automated identification of patient-ventilator asynchrony. However, training a high-performing neural network often requires a large amount of labeled data. Obtaining this labeled data requires significant effort from medical staff to sift through long periods of continuous respiratory waveforms and label them, undoubtedly increasing time costs. Even if a well-trained neural network capable of identifying patient-ventilator asynchrony is developed, it doesn't help in investigating the causes of asynchrony. Clinically, to investigate patient-ventilator asynchrony, the intensity and timing of the patient's spontaneous breathing are first determined, often using methods such as measuring esophageal pressure and diaphragmatic electromyography. However, measuring esophageal pressure is an invasive procedure that can cause pain for the patient. Summary of the Invention

[0003] The purpose of this invention is to reduce the cost of obtaining labeled human-machine asynchronous waveforms by providing a method for simulating and generating human-machine asynchronous waveforms based on mathematical modeling.

[0004] The objective of this invention is achieved as follows:

[0005] A method for simulating and generating asynchronous waveforms between humans and machines based on mathematical modeling, the method comprising:

[0006] A mathematical model of the human respiratory system is established using the electrical network model method. The respiratory system is divided into four parts: the larynx, trachea, bronchi, and alveoli, represented by linear resistors and linear capacitors, respectively. Key physiological parameters of the respiratory system are equivalent to circuit parameters: airway pressure is equivalent to voltage, flow velocity to current, airway resistance to resistance, and airway compliance to capacitance. A voltage source, P, is added at the connection points representing the trachea, bronchi, and alveoli in the electrical network model to represent the driving pressure source P for spontaneous breathing. musThe respiratory system mathematical model specifically includes alveolar linear resistance, alveolar linear capacitance, bronchial linear resistance, bronchial linear capacitance, tracheal linear resistance, tracheal linear capacitance, larynx linear resistance, larynx linear capacitance, chest wall linear capacitance, and a driving force voltage source. The alveolar linear resistance, bronchial linear resistance, tracheal linear resistance, and larynx linear resistance are connected sequentially. The other end of the larynx linear resistance is open-circuited. The other end of the alveolar linear resistance is connected to one end of the alveolar linear capacitance. One end of the bronchial linear capacitance is connected to the junction of the alveolar and bronchial linear resistances. One end of the tracheal linear capacitance is connected to the junction of the tracheal and bronchial linear resistances. The other ends of the alveolar, bronchial, and tracheal linear capacitances are connected to one end of the chest wall linear capacitance. The other end of the chest wall linear capacitance is connected to the positive port of the driving force voltage source, and the negative port of the driving force voltage source is grounded. One end of the larynx linear capacitance is connected to the junction of the larynx and tracheal linear resistances, and the other end is grounded.

[0007] The mathematical model of the ventilator, similar to that of the human respiratory system, employs an electrical network model. The ventilator's mathematical model uses a voltage source, P, to represent the pressure source P that delivers air into the patient's airway during operation. vent The resistance and elasticity of the ventilator's air delivery tubing will be represented by resistance and capacitance. The mathematical model of the ventilator includes: the linear resistance R of the ventilator tubing. tube The system consists of a pressure source, a voltage source, and a linear capacitor in the ventilator tubing. One end of the linear resistor in the ventilator tubing serves as the pressure output terminal, and the other end is connected to the positive port of the pressure source / voltage source. The negative port of the pressure source / voltage source is grounded. One end of the linear capacitor in the ventilator tubing is connected to the linear resistor in the ventilator tubing, and the other end is grounded.

[0008] The linear resistor in the ventilator tubing is connected to the open-circuit end of the linear resistor in the larynx to establish a coupled model of the mathematical model of the ventilator and the mathematical model of the human respiratory system: the mechanical ventilation model.

[0009] A system of differential equations is established to describe the mechanical ventilation model. Based on the characteristics of the mechanical ventilation mode and the human-machine asynchrony category, the P in the mechanical ventilation model is adjusted. vent Size, time, and driving pressure P of human spontaneous respiration mus The magnitude and duration of the equations are determined, initial conditions and solution intervals are set, and the system of differential equations is solved to simulate and generate the corresponding human-machine asynchrony waveforms for different categories of human-machine asynchrony.

[0010] Furthermore, the mathematical model of the human respiratory system specifically refers to the airway pressure model, which assumes that the gas is an ideal gas, ignores the turbulence effect of the airflow, and the entire system follows Poiseuille's law.

[0011] Furthermore, the driving pressure source P representing human spontaneous breathing mus Let be a piecewise continuous function with respect to the respiratory cycle, whose shape satisfies the trend of decreasing from 0 to the minimum inspiratory pressure during the inspiratory phase and gradually returning to 0 from the minimum inspiratory pressure during the expiratory phase. The specific function is:

[0012]

[0013] Furthermore, the driving pressure source P representing human spontaneous breathing mus In the formula, the symbols are defined as follows:

[0014] P mus,min Minimum inhalation pressure

[0015] T: respiratory cycle time

[0016] T I Inhalation time

[0017] T E : Exhalation time

[0018] τ: Time constant of the expiratory profile

[0019] Furthermore, P represents the pressure source P that delivers air into the patient's airway when the medical ventilator is operating. vent The generation control adopts proportional-integral-derivative control.

[0020] Furthermore, the established coupled model consists of a ventilator mathematical model and a human respiratory system mathematical model. The coupling method involves connecting the pressure output terminal of the ventilator mathematical model to the larynx of the human respiratory system mathematical model. The equations of motion for the coupled system are:

[0021]

[0022] In the formula P mus Striving for independent breathing, P vent V is the inspiratory pressure output by the ventilator. T tidal volume, F is inspiratory flow rate, C is respiratory system compliance, and R is respiratory system resistance.

[0023] Furthermore, the respiratory system compliance C in the above system motion equation consists of five parts in this invention, and the calculation method is as follows:

[0024]

[0025] In the formula C l Represents laryngeal compliance, C t Represents tracheal compliance, C b Represents bronchial compliance, CA Represents alveolar compliance, C cw It represents chest wall compliance.

[0026] Furthermore, the respiratory system resistance R in the above system motion equation consists of five parts in this invention, and the calculation method is as follows:

[0027] R = R l +R t +R b +R A

[0028] In the formula R l R represents laryngeal resistance. t R represents tracheal resistance. b R represents bronchial resistance. A This represents alveolar resistance.

[0029] Furthermore, based on the established coupled model: the mechanical ventilation model, a system of differential equations was derived. The method for solving the system of differential equations using the fourth- to fifth-order Runge-Kutta method with a fixed step size was adopted, with a simulation step size of 0.01s.

[0030] Furthermore, the mechanical ventilation modes include volume control and pressure control. In volume control mode, the categories of human-machine asynchrony include: ineffective inspiratory effort and dual triggering. In pressure control mode, the categories of human-machine asynchrony include: ineffective inspiratory effort, dual triggering, cycle too short, and cycle too long.

[0031] Furthermore, the method for implementing volume-controlled and pressure-controlled ventilation modes in the mechanical ventilation model involves simulating the working mode of a clinical ventilator, including two parts: ventilator-triggered inhalation and controlled ventilation after inhalation, specifically:

[0032] Let the current time be t, and the mechanical ventilation inhalation time be t. inmech The duration of mechanical ventilation is t. totmech The trigger control airflow velocity is F trigger The target ventilation pressure value P for pressure control set The target ventilation velocity value F for capacity control set .

[0033] a. For ventilator triggering, it refers to the expiratory phase, i.e., t inmech <t≤t totmech By detecting the inspiratory flow rate F in the throat aw If F aw <F trigger If F aw ≥F triggerIf the exhalation phase is not triggered, then proceed to step b or c below, and simultaneously set the current time t to zero. If no exhalation is triggered during the entire exhalation phase, then when t = t totmech When the current time t is set to zero, the trigger will be forced to start the gas release; this is a time-forced trigger.

[0034] b. For pressure control, when 0≤t≤t inmech During the inspiratory phase, the output pressure P of the ventilator is controlled by the proportional-integral-differential mathematical model. vent The airway pressure P in the throat aw Stabilize at the set inhalation pressure value P set When t inmech <t≤t totmech During the exhalation phase, the output pressure P of the ventilator mathematical model is set. vent It can be zero or a specific positive end-expiratory pressure.

[0035] c. For capacity control, when 0 ≤ t ≤ t inmech During the inspiratory phase, the output pressure P of the ventilator is controlled by the proportional-integral-differential mathematical model. vent The inhalation speed F in the throat aw Stabilize at the set inhalation flow rate value F set When t inmech <t≤t totmech During the exhalation phase, the output pressure P of the ventilator mathematical model is set. vent It can be zero or a specific positive end-expiratory pressure.

[0036] Furthermore, based on the characteristics of the mechanical ventilation mode and the human-machine asynchrony category, the P in the mechanical ventilation model is adjusted. vent Size, time, and driving pressure P of human spontaneous respiration mus The size and duration of action are as follows:

[0037] Let P be the driving pressure for spontaneous human respiration. mus The minimum value is P musmin The inhalation time for spontaneous human respiration is T. I Expiratory time is T E The inspiratory time for mechanical ventilation is t. inmech The duration of mechanical ventilation is t. totmech The trigger control airflow velocity is F trigger .

[0038] a. For ineffective inspiratory effort, it refers to the laryngeal inspiratory flow rate F caused by spontaneous breathing when both spontaneous breathing and mechanical ventilation are present. aw Unable to trigger control airflow velocity F trigger The size of the pressure. Therefore, the driving pressure P for spontaneous human respiration. musThe minimum value needs to satisfy The inspiratory time of spontaneous human breathing meets T I =t inmech .

[0039] b. For double triggering, this refers to a situation where both spontaneous breathing and mechanical ventilation are present, and the duration of spontaneous breathing is too long, causing two triggerings to control ventilation within the body's spontaneous inhalation time. Therefore, the driving pressure P for spontaneous breathing... mus The minimum value needs to satisfy The inspiratory time of spontaneous human breathing meets T I >2t inmech .

[0040] c. A short cycle refers to a situation where, in the presence of both spontaneous breathing and mechanical ventilation, mechanical ventilation switches to expiration prematurely before the inspiratory phase of spontaneous breathing has ended, resulting in an excessively short mechanical ventilation cycle. Therefore, the driving pressure P for spontaneous breathing... mus The minimum value needs to satisfy The inspiratory time of spontaneous human breathing meets T I <t inmech .

[0041] d. A prolonged cycle occurs when both spontaneous breathing and mechanical ventilation are present, but mechanical ventilation fails to switch to expiration in time at the end of the inspiratory phase of spontaneous breathing, resulting in an excessively long mechanical ventilation cycle. Therefore, the driving pressure P for spontaneous breathing... mus The minimum value needs to satisfy The inspiratory time of spontaneous human breathing meets T I >t inmech .

[0042] Compared with the prior art, the beneficial effects of the present invention are:

[0043] This invention presents a method for simulating and generating asynchronous human-machine waveforms based on mathematical modeling. By employing mathematical modeling, a coupled model of the human respiratory system and a ventilator is established. This solves the problem of the difficulty in acquiring labeled asynchronous respiratory waveform data. It provides a new approach and perspective for studying this medical phenomenon. Compared with existing technologies, the respiratory waveforms generated by the mathematical model proposed in this invention have a certain degree of interpretability. The respiratory system mathematical model of this invention adopts a structure from the larynx, trachea, bronchi to alveoli, which is consistent with the actual physiological structure. Through adjustable spontaneous breathing rhythm and intensity, combined with diverse ventilator ventilation modes, each simulated waveform has physiological interpretability. Attached Figure Description

[0044] Figure 1 This is a flowchart illustrating a method for simulating and generating asynchronous waveforms between humans and machines according to the present invention.

[0045] Figure 2 This is the mathematical model of the human respiratory system proposed in this invention.

[0046] Figure 3 This invention presents a coupling model of the human respiratory system and a ventilator.

[0047] Figure 4 This is the control strategy for the mechanical ventilation model in this invention.

[0048] Figure 5 This is a waveform diagram of human-machine asynchrony under simulated pressure control during an embodiment of the present invention.

[0049] Figure 6 The waveform diagram is a simulated waveform diagram of human-machine asynchrony under ineffective inspiratory effort under volume control in an embodiment of the present invention.

[0050] Figure 7 The waveform diagram is a simulated waveform diagram of human-machine asynchrony under dual triggering under pressure control generated in an embodiment of the present invention.

[0051] Figure 8 The waveform diagram is a simulated waveform diagram of dual-triggered human-machine asynchrony under capacity control generated in an embodiment of the present invention.

[0052] Figure 9 This is a waveform diagram of human-machine asynchrony under simulated pressure control with an excessively short cycle, generated in an embodiment of the present invention.

[0053] Figure 10 This is a waveform diagram of human-machine asynchrony under simulated pressure control with an excessively long cycle, generated in an embodiment of the present invention. Detailed Implementation

[0054] To better explain and facilitate understanding of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0055] like Figure 1 As shown, the present invention is a method for simulating and generating asynchronous waveforms between humans and machines, comprising the following steps:

[0056] S1. Mathematical modeling of the human respiratory system;

[0057] See Figure 2 An electrical network model was used to establish a mathematical model of the respiratory system. The airway was divided into four parts: the larynx, trachea, bronchi, and alveoli, each represented by a linear resistor and a linear capacitor. A voltage source was added at the connection points of the trachea, bronchi, and alveoli to represent the driving pressure P of human spontaneous breathing. musAmong them, airway pressure is equivalent to voltage, flow rate is equivalent to current, airway resistance is equivalent to resistance, and airway compliance is equivalent to capacitance; the driving force enables spontaneous breathing, that is, pressure is generated by the respiratory muscles (respiratory muscle pressure, P). mus The mathematical model driving the entire respiratory system generates respiratory waveforms. The driving force component also considers the pressure within the chest wall and pleural cavity (intrapleural pressure, P). pl The chest wall can be considered an elastic structure, and its pressure-volume characteristic curve is assumed to be linear, represented by a linear capacitor in the equivalent circuit model. Since the viscous resistance of the chest wall has a negligible impact on the overall respiratory system resistance under physiological and pathological conditions, its effect on blood flow is ignored. Driving force P mus Linked to the compliance of the chest wall acting on the pleural cavity, it increases the intrapleural pressure P. pl It shifts to the three cavities affected by the pleural cavity: the trachea, bronchi, and alveoli.

[0058] Specifically, the mathematical model of the respiratory system includes: alveolar linear resistance R A alveolar linear capacitance C A bronchial linear resistance R b 1. Bronchial linear capacitance C b tracheal linear resistance R t tracheal linear capacitance C t Throat linear resistance R l Throat linear capacitance C l Linear capacitance of the chest wall C CW and driving force voltage source P mus The specific connection method is as follows: alveolar linear resistance R A One end and alveolar linear capacitance C A One end is connected in series, alveolar linear resistance R A The other end and the linear resistance R of the bronchus b One end is connected in series. The linear capacitance of the bronchus, C. b One end is connected to the alveolar linear resistor R A and bronchial linear resistance R b Connection point, bronchial linear capacitance C b The other end is connected to the other end of the alveolar linear capacitance. The tracheal linear resistance R... t One end and the linear resistance R of the bronchus b The other end is connected in series, and the tracheal linear capacitor C t One end is connected to the linear resistor R in the trachea. t and bronchial linear resistance R b The connection point, the linear capacitance C of the trachea t The other end is connected to the junction of the alveolar linear capacitance and the bronchial linear capacitance. The laryngeal linear resistance R... lOne end is connected to the linear resistor R in the trachea. t At the other end, the throat linear capacitance C l One end is connected to the throat linear resistor R l And the linear resistance R of the trachea t The connection point, the throat linear capacitance C l The other end is connected to the ground terminal. Throat linear resistance R l The other end is open, representing the opening of the airway. Chest wall linear capacitance C CW One end is connected to the tracheal linear capacitor C t 1. Bronchial linear capacitance C b and alveolar linear capacitance C A The connection point, the linear capacitance C of the chest wall CW The other end is connected to the driving force voltage source P. mus Positive port, driving force voltage source P mus The negative port is grounded.

[0059] S2. Establish a coupled model of the mathematical model of the ventilator and the mathematical model of the human respiratory system: mechanical ventilation model;

[0060] See Figure 3 The laryngeal airway opening of the respiratory system model is connected to the ventilator model. The mathematical model of the ventilator uses a voltage source to represent the pressure source P that delivers air into the patient's airway when the medical ventilator is working. vent The resistance and elasticity of the ventilator's air delivery tubing will be represented by resistance and capacitance. The specific connection method is as follows: ventilator tubing linear resistance R... tube One end is connected to the throat linear resistor R described in S1. l The other end is open circuit, and the linear resistance R of the ventilator tubing tube The other end is connected to the pressure source voltage source P. vent Positive port, pressure source voltage source P vent The negative port is grounded. The linear capacitance C of the ventilator tubing. tube One end is connected to the linear resistor R in the ventilator tubing tube and throat linear resistance R l The connection point, the linear capacitance C of the ventilator tubing tube The other end is grounded.

[0061] The system equations of motion for the mechanical ventilation model are expressed as follows:

[0062]

[0063] In the formula P mus Striving for independent breathing, P vent V is the inspiratory pressure output by the ventilator. T Here, F represents tidal volume, F represents inspiratory flow rate, and C represents respiratory system compliance. R is the respiratory system resistance, R = R l +R t +R b +R A .

[0064] In the formula, C l Represents laryngeal compliance, C t Represents tracheal compliance, C b Represents bronchial compliance, C A Represents alveolar compliance, C cw Represents chest wall compliance, R l R represents laryngeal resistance. t R represents tracheal resistance. b R represents bronchial resistance. A This represents alveolar resistance. Table 1 provides a detailed list of circuit component assignments for an exemplary use.

[0065] Table 1 shows the detailed circuit component values ​​used in the embodiments.

[0066]

[0067] S3. Based on the coupled model of the established mathematical model of the ventilator and the mathematical model of the human respiratory system: the mechanical ventilation model, list the system of differential equations;

[0068] The definitions of each symbol are as follows:

[0069] R tube : Represents the resistance of the ventilator tubing

[0070] P l : Represents throat pressure

[0071] P aw : Represents the pressure at the ventilator connection point

[0072] P t : Represents tracheal pressure

[0073] P b : Represents bronchial pressure

[0074] P A : Represents alveolar pressure

[0075] P pl : Represents intrapleural pressure

[0076] P mus : Represents respiratory muscle pressure

[0077] P vent : Represents the ventilator output pressure

[0078]

[0079] Among them, P represents the driving pressure source of human spontaneous breathing. mus Let be a piecewise continuous function with respect to the respiratory cycle, whose shape satisfies the trend of decreasing from 0 to the minimum inspiratory pressure during the inspiratory phase and gradually returning to 0 from the minimum inspiratory pressure during the expiratory phase. The specific function is:

[0080]

[0081] Among them, P mus,min T represents the minimum inspiratory pressure, and T represents the respiratory cycle time. I T represents the inhalation time. E τ represents the exhalation time, and τ represents the time constant of the exhalation profile.

[0082] S4, the mechanical ventilation model enables multiple ventilation modes, including capacity control and pressure control;

[0083] The mechanical ventilation model is controlled using proportional-integral-derivative (PID) control as an example. (See [link to relevant documentation]). Figure 4 The main control steps are as follows:

[0084] First, read the preset parameters, including the current time t, the mechanical ventilation control mode, and the mechanical ventilation inspiratory time t. inmech Inhalation target pressure P set Mechanical ventilation duration t totmech Positive end-expiratory pressure (PEEP), inspiratory flow rate (F) set The trigger control airflow velocity is F trigger .

[0085] a. For ventilator triggering, it refers to the expiratory phase, i.e., t inmech <t≤t totmech By detecting the inspiratory flow rate F in the throat aw If F aw <F trigger If F aw ≥F trigger If the exhalation phase is not triggered, then proceed to step b or c, and simultaneously set the current time t to zero. If no exhalation is triggered during the entire exhalation phase, then when t = t totmech When the current time t is set to zero, the trigger will be forced to start the gas release; this is a time-forced trigger.

[0086] b. For pressure control, when 0≤t≤t inmech During the inspiratory phase, the output pressure P of the ventilator is controlled by the proportional-integral-differential mathematical model. vent The airway pressure P in the throat aw Stabilize at the set inhalation pressure value Pset When t inmech <t≤t totmech During the exhalation phase, the output pressure P of the ventilator mathematical model is set. vent It can be zero or a specific positive end-expiratory pressure (PEEP).

[0087] c. For capacity control, when 0 ≤ t ≤ t inmech During the inspiratory phase, the output pressure P of the ventilator is controlled by the proportional-integral-differential mathematical model. vent The inhalation speed F in the throat aw Stabilize at the set inhalation flow rate value F set When t inmech <t≤t totmech During the exhalation phase, the output pressure P of the ventilator mathematical model is set. vent It can be zero or a specific positive end-expiratory pressure (PEEP).

[0088] In this embodiment, the proportional-integral-derivative (PID) control parameters (proportional coefficient Kp, integral coefficient Ki, and derivative coefficient Kd) for pressure control are 0.1, 0, and 0.01, respectively; and the PID control parameters for capacity control are 3.2, 0.01, and 0, respectively.

[0089] S5. Set initial conditions and solve the system of differential equations in the solution interval;

[0090] The fourth- to fifth-order Runge-Kutta method with a fixed step size was used to solve the differential equations. The simulation step size was 0.01 s, and the initial conditions were set as an array of length 6 and values ​​of 0.1. The error tolerance was set to absolute error tolerance with a threshold of 10. -6 .

[0091] S6. Adjust P in the mechanical ventilation model according to the characteristics of the mechanical ventilation mode and the human-machine asynchrony category. vent Size, time and / or driving pressure P of spontaneous human respiration mus The magnitude and duration of the equations are determined; initial conditions and solution intervals are set to solve the system of differential equations, and human-machine asynchrony waveforms corresponding to the human-machine asynchrony categories are simulated and generated.

[0092] Among them, adjusting P in the mechanical ventilation model vent Size, time and / or driving pressure P of spontaneous human respiration mus The adjustment mechanism for the size and duration of action is designed to meet the characteristics of mechanical ventilation modes and human-machine asynchrony categories, thus fixing the P value in the mechanical ventilation model. vent The magnitude and time are used as preset values ​​to change the driving pressure P of human spontaneous breathing. mus Its size and duration of action allow it to meet the characteristics of mechanical ventilation modes and patient-ventilator asynchrony categories, or to fix the driving pressure P of spontaneous breathing.mus The magnitude and duration of action of P in the mechanical ventilation model are changed. vent The magnitude and time are preset values ​​that are changed to meet the characteristics of mechanical ventilation modes and human-machine asynchrony categories, so as to fix P in the mechanical ventilation model. vent The magnitude and time are preset values ​​(see Table 2) to change the driving pressure P of human spontaneous breathing. mus Using the size and duration of action as examples, generate human-machine asynchronous waveforms;

[0093] Table 2 shows the preset parameter settings in this example.

[0094]

[0095] In this embodiment, the driving pressure P of spontaneous breathing is used to generate the asynchronous waveform of ineffective inspiratory effort between the human and machine. mus Minimum value P musmin The size is set to -2cmH2O, which satisfies The inhalation time for spontaneous human breathing is 1.5 seconds, which meets the T... I =t inmech For the generation of asynchronous waveforms in dual-triggered human-machine interaction, the driving pressure P of spontaneous human breathing... mus Minimum value P musmin The size is set to -7cmH2O, which satisfies The inhalation time for spontaneous human respiration is 3 seconds, which meets the T... I >2t inmech For the generation of asynchronous waveforms between humans and machines with excessively short cycles, the driving pressure P of spontaneous human breathing... mus The minimum value is set to -5cmH2O, which satisfies... The inhalation time for spontaneous human breathing is set to 1 second, which meets the T... I <t inmech For the generation of human-machine asynchronous waveforms with excessively long periods, the driving pressure P of spontaneous human breathing... mus The minimum value is set to -5cmH2O, which satisfies... The inspiratory time for spontaneous human breathing is set to 2 seconds, which meets the T... I >t inmech .

[0096] Figure 5 The waveform diagram of ineffective inspiratory effort and human-machine asynchrony under pressure control, generated in an embodiment of the present invention, is characterized by a downward dip in the pressure (P) waveform and an upward spike in the flow rate (F) waveform between the 5th and 6th seconds. This is consistent with the waveform characteristics of ineffective inspiratory effort and human-machine asynchrony under pressure control in clinical practice.

[0097] Figure 6This is a waveform diagram of ineffective inspiratory effort and human-machine asynchrony under volume control, generated in an embodiment of the present invention. Its main characteristic is that between the 5th and 6th seconds, the pressure (P) waveform shows a downward dip, while the flow rate (F) waveform shows a small upward spike. This is consistent with the waveform characteristics of ineffective inspiratory effort and human-machine asynchrony under volume control in clinical practice.

[0098] Figure 7 This is a waveform diagram of simulated pressure-controlled dual-trigger human-machine asynchrony generated in an embodiment of the present invention. Its main characteristic is that from the 5th second to the 10th second, the pressure (P) and flow (F) waveforms show that a second inhalation is triggered after the completion of one inhalation but before the completion of exhalation. Tidal volume (V) shows a second increase. This is consistent with the waveform characteristics of pressure-controlled dual-trigger human-machine asynchrony in clinical practice.

[0099] Figure 8 This is a waveform diagram of simulated human-machine asynchrony under dual-triggering volume control, generated in an embodiment of the present invention. Its main characteristic is that from the 5th second to the 10th second, the pressure (P) and flow (F) waveforms show that a second inhalation is triggered after the end of one inhalation but before the end of exhalation. Tidal volume (V) increases twice. This is consistent with the waveform characteristics of human-machine asynchrony under dual-triggering volume control in clinical practice.

[0100] Figure 9 This is a waveform diagram of human-ventilator asynchrony under pressure-controlled short cycle in an embodiment of the present invention. Its main feature is that from the 2nd to the 4th second, the flow rate (F) waveform shows a small upward spike during exhalation, which is consistent with the waveform characteristics of human-ventilator asynchrony under pressure-controlled short cycle in clinical practice.

[0101] Figure 10 This is a waveform diagram of human-machine asynchrony under excessively long cycle time under pressure control, generated in an embodiment of the present invention. Its main feature is that from the 2nd to the 4th second, the pressure (P) waveform shows a small upward peak at the end of inspiration, and the flow rate (F) waveform shows a rapid drop to zero at the end of inspiration. This is consistent with the waveform characteristics of human-machine asynchrony under excessively long cycle time under pressure control in clinical practice.

[0102] This invention is a method for simulating and generating human-machine asynchrony waveforms based on mathematical modeling. In the embodiments, a respiratory system and ventilator with specific physiological parameters are mathematically modeled and coupled. By setting control parameters and performing simulation calculations, human-machine asynchrony waveforms of ineffective inspiratory effort, double triggering, excessively short cycle, and excessively long cycle can be generated in pressure control mode, and ineffective inspiratory effort and double triggering human-machine asynchrony waveforms in volume control mode. However, this invention is not limited to the simulation and generation of the above-mentioned types of human-machine asynchrony waveforms; it has general applicability to the simulation and generation of other types of human-machine asynchrony waveforms.

[0103] The proposed method for simulating human-ventilator asynchrony waveforms maps the physiological structure of the human respiratory system to an electrical network, employing a structure from the larynx, trachea, bronchi to alveoli, consistent with the actual physiological structure. This allows for a better interpretation of the physiological basis of each simulated waveform. The coupling between the ventilator model and the respiratory system model references the invasive use of real clinical ventilators, and the mechanical ventilation control strategy also references widely used clinical ventilation modes. Through reasonable and effective respiratory system modeling and ventilator control strategies, the effectiveness and interpretability of the model are further improved, addressing the challenge of acquiring labeled human-ventilator asynchrony respiratory waveform data. This provides a new approach and perspective for studying the medical phenomenon of human-ventilator asynchrony.

[0104] In the above embodiments, the present invention has only been described exemplarily. However, those skilled in the art can make various modifications to the present invention without departing from the spirit and scope of the present invention after reading this patent application.

Claims

1. A method for simulating and generating asynchronous waveforms between humans and machines, characterized in that, The method includes: An electrical network model was used to establish a mathematical model of the respiratory system, which was divided into four parts: the larynx, trachea, bronchi, and alveoli. Each part was represented by a linear resistor and a linear capacitor connected in series. A voltage source was added at the connection points of the trachea, bronchi, and alveoli to represent the driving pressure of spontaneous breathing. Among them, airway pressure is equivalent to voltage, flow rate is equivalent to current, airway resistance is equivalent to resistance, and airway compliance is equivalent to capacitance. A mathematical model of the ventilator is established using the electrical network model method. This mathematical model uses a voltage source to represent the pressure of the air delivered into the patient's airway during operation of the medical ventilator. The resistance and elasticity of the ventilator's air delivery tubing will be represented by resistance and capacitance. A mechanical ventilation model is obtained by coupling the ventilator mathematical model and the human respiratory system mathematical model by connecting the pressure output terminal of the ventilator mathematical model to the larynx of the human respiratory system mathematical model. A system of differential equations is established to describe the mechanical ventilation model. Based on the characteristics of the mechanical ventilation mode and the type of human-machine asynchrony, adjustments are made to the mechanical ventilation model. Size, time, and driving pressure of human spontaneous breathing The magnitude and duration of the equations are determined, initial conditions and solution intervals are set, and the system of differential equations is solved to simulate and generate the corresponding human-machine asynchrony waveforms for different categories of human-machine asynchrony.

2. The method according to claim 1, characterized in that, The specific steps for establishing a system of differential equations to describe the mechanical ventilation model are as follows: in, Represents throat compliance. Represents tracheal compliance. Represents bronchial compliance. Represents alveolar compliance. Represents chest wall compliance. Represents ventilator tubing compliance. Represents throat resistance. Represents tracheal resistance. Represents bronchial resistance. Represents alveolar resistance. Represents the resistance of the ventilator tubing. Represents throat pressure. This represents the pressure at the ventilator connection point. Represents tracheal pressure. Represents bronchial pressure. Represents alveolar pressure, Represents intrapleural pressure. Represents respiratory muscle pressure. This represents the output pressure of the ventilator.

3. The method according to claim 1, characterized in that, The driving pressure representing human spontaneous breathing It is set as a piecewise continuous function with respect to the respiratory cycle, the function shape satisfying the trend of decreasing from 0 to the minimum inspiratory pressure value during the inspiration phase and gradually returning to 0 from the minimum inspiratory pressure value during the expiration phase; the specific function is expressed as: in, Indicates the minimum inhalation pressure. Indicates the respiratory cycle time. Indicates the inhalation time. Indicates the exhalation time. This represents the time constant of the expiratory profile.

4. The method according to claim 1, characterized in that, This represents the pressure source that delivers air into the patient's airway when the medical ventilator is working. The generation control adopts proportional-integral-derivative control.

5. The method according to claim 1, characterized in that, The system equation of motion for the mechanical ventilation model is: In the formula The driving pressure for the body's autonomous respiration. The pressure at which air is delivered into the patient's airway when the ventilator is working. Tidal volume, The intake airflow rate, For respiratory system compliance, , For respiratory system resistance, ; In the formula, Represents throat compliance. Represents tracheal compliance. Represents bronchial compliance. Represents alveolar compliance. Represents chest wall compliance. Represents throat resistance. Represents tracheal resistance. Represents bronchial resistance. This represents alveolar resistance.

6. The method according to claim 1, characterized in that, The method for solving the differential equation system is the fourth- to fifth-order Runge-Kutta method with a fixed step size of 0.01s.

7. The method according to claim 1, characterized in that, The mechanical ventilation modes include volume control and pressure control. In volume control mode, the categories of human-machine asynchrony include: ineffective inspiratory effort and double triggering. In pressure control mode, the categories of human-machine asynchrony include: ineffective inspiratory effort, double triggering, too short a cycle, and too long a cycle.

8. The method according to claim 7, characterized in that, The mechanical ventilation model is adjusted according to the characteristics of mechanical ventilation modes and human-machine asynchrony categories. Size, time, and driving pressure of human spontaneous breathing The size and duration of action are as follows: In volume control mode or pressure control mode, when the human-machine asynchrony is classified as ineffective inspiratory effort, the driving pressure of spontaneous breathing is... The minimum value needs to satisfy The inhalation time of spontaneous human breathing meets the requirements. ; In either volume control or pressure control mode, when the human-machine asynchrony category is dual-triggered, the driving pressure for spontaneous breathing is... The minimum value needs to satisfy The inhalation time of spontaneous human breathing meets the requirements. ; In pressure control mode, the human-machine asynchrony category is when the cycle is too short, affecting the driving pressure of spontaneous breathing. The minimum value needs to satisfy The inhalation time of spontaneous human breathing meets the requirements. ; In pressure control mode, the human-machine asynchrony category is when the cycle is too long, affecting the driving pressure of the human body's spontaneous breathing. The minimum value needs to satisfy The inhalation time of spontaneous human breathing meets the requirements. ; in, Tidal volume, For respiratory system compliance, For respiratory system resistance, To trigger control of the airflow rate, Indicates the inhalation time. This refers to the inspiratory time during mechanical ventilation.

9. The method according to claim 7, characterized in that, In pressure control mode, when During the inspiratory phase, the output pressure of the ventilator is controlled by the proportional-integral-differential mathematical model. This will reduce airway pressure in the throat. Stabilize at the set inhalation pressure value ;when During the exhalation phase, set the output pressure of the ventilator mathematical model. It is zero or a specific positive end-expiratory pressure; where, This refers to the inspiratory time during mechanical ventilation. This refers to the duration of mechanical ventilation. In capacity control mode, when During the inspiratory phase, the output pressure of the ventilator is controlled by the proportional-integral-differential mathematical model. Increase the inhalation speed in the throat Stabilize at the set inhalation flow rate value ;when During the exhalation phase, set the output pressure of the ventilator mathematical model. Zero or a specific positive end-expiratory pressure; Among them, by detecting the inspiratory flow rate in the larynx If mechanical ventilation control is triggered at time t during the expiratory phase, If mechanical ventilation is not triggered during the entire expiratory phase, mechanical ventilation will be forcibly triggered on the next breath.

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