A portable ventilator suitable for cardiopulmonary resuscitation and its control method

Abstract

The present invention provides a portable ventilator suitable for cardiopulmonary resuscitation and a control method thereof. The present invention can automatically identify the number of chest compressions during CPR based on reverse airflow, and simultaneously judge the compression period and relaxation period. It has automatic 30:2 ventilation suitable for non-intubated patients and a variable volume ventilation mode suitable for patients with advanced airway establishment. It can improve first aid efficiency while avoiding barotrauma, is more suitable for first aid during CPR, and accurately controls the flow rate.

Description

Technical Field

[0001] The invention belongs to the technical field of ventilator control and relates to a portable ventilator suitable for cardiopulmonary resuscitation and a control method thereof. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] Cardiac arrest (CA) refers to the sudden cessation of cardiac ejection, the disappearance of arterial pulsation and heart sounds, and severe ischemia and hypoxia in vital organs, leading to the end of life. CA is a major cause of death, and the survival rate is further reduced in out-of-hospital cardiac arrest (OHCA).

[0004] Cardiopulmonary resuscitation (CPR) is an important means of treating cardiac arrest and generally consists of electric defibrillation, cardiopulmonary resuscitation, and respiratory ventilation. In OHCA, non-invasive ventilation and a 30:2 ventilation mode are used to ensure adequate perfusion for patients without an advanced airway. However, 30:2 ventilation requires rescuers to count compressions and turn on the ventilator after 30 chest compressions or use an emergency air bag for two ventilations. After endotracheal intubation and establishment of an advanced airway, the CPR process will use uninterrupted compressions and continuous ventilation at a ventilation rate of 10 times / minute. The advanced airway mode ensures that the patient can obtain an adequate oxygen supply during CPR.

[0005] However, according to the inventor's understanding, existing ventilators are unable to perform 30:2 ventilation and advanced airway ventilation well, mainly manifested in: for 30:2 ventilation, existing ventilators cannot actively identify the occurrence of compression events, cannot automatically capture the number of compressions, and cannot actively complete ventilation tasks, and the ventilation process requires manual operation; for advanced airway modes, modern ventilators use pressure support ventilation, volume control ventilation or continuous positive pressure ventilation mode to provide continuous positive pressure ventilation, but the inspiratory period of positive pressure ventilation and the compression period of chest compression overlap, causing the patient's airway pressure to surge and the risk of barotrauma to increase. Summary of the Invention

[0006] In order to solve the above problems, the present invention proposes a portable ventilator suitable for cardiopulmonary resuscitation and a control method thereof. The present invention can automatically identify the number of chest compressions during CPR based on reverse airflow, and at the same time judge the compression period and relaxation period. It has automatic 30:2 ventilation suitable for non-intubated patients and a variable volume ventilation mode suitable for patients with advanced airway establishment. It can improve the efficiency of first aid and avoid barotrauma at the same time. It is more suitable for first aid during CPR and can accurately control the flow rate.

[0007] According to some embodiments, the present invention adopts the following technical solutions:

[0008] A portable ventilator suitable for cardiopulmonary resuscitation, comprising a blower, an air-oxygen mixer, a pipeline, a controller and a flow sensor, wherein:

[0009] The air inlet of the blower is connected to the air-oxygen mixer, and the outlet is connected to one end of the oxygen sensor;

[0010] The other end of the oxygen sensor is connected to the gas inlet of the flow sensor to monitor the flow rate. The outlet of the flow sensor is connected to a pipeline, and a control switch is provided on the pipeline for closing the pipeline;

[0011] The pipeline is also provided with a pressure sensor to monitor the gas pressure in the pipeline;

[0012] The controller communicates with the flow sensor and the pressure sensor, and is used to perform feedback control on the blower based on the monitoring data of the sensors to ensure the provision of gas at a constant flow rate.

[0013] As an optional embodiment, one end of the air-oxygen mixer is connected to the atmosphere, and the other end is connected to a proportional solenoid valve, and the inlet of the proportional solenoid valve is connected to an oxygen source.

[0014] As an optional implementation, a power supply module is further included to provide voltage for other modules.

[0015] As an optional embodiment, the controller is configured to compare the actual flow rate obtained by the flow sensor with the preset flow rate, and adjust the flow rate of the ventilator based on the comparison difference to generate the PWM value required by the blower.

[0016] As an optional embodiment, the controller is configured to determine whether the reverse airflow is caused by compression through time and flow parameters during cardiopulmonary resuscitation, and count the reverse airflow caused by compression. When an advanced airway is not established, the controller reads the number of compressions and performs ventilation after the compressions are completed.

[0017] As an optional embodiment, the controller is configured to determine the optimal control parameters after establishing an advanced airway, complete the control of the airway flow, judge the compression period and relaxation period of chest compression based on the reverse airflow caused by compression, reduce the fan speed or turn off the fan during the compression period, and increase the fan speed during the relaxation period.

[0018] The above-mentioned ventilator control method comprises the following steps:

[0019] Obtain monitoring data from flow sensors and pressure sensors;

[0020] Compare the actual flow rate obtained by the flow sensor with the preset flow rate, and adjust the flow rate of the ventilator based on the comparison difference to generate the PWM value required by the fan;

[0021] During cardiopulmonary resuscitation, the system uses time and flow parameters to determine whether reverse airflow is caused by compressions, and counts the reverse airflow caused by compressions. If an advanced airway is not established, the system reads the number of compressions and performs ventilation after the compressions are completed.

[0022] After establishing an advanced airway, determine the optimal control parameters to complete the control of airway flow. Judge the compression period and relaxation period of chest compression based on the reverse airflow caused by compression. Reduce the fan speed or turn off the fan during the compression period, and increase the fan speed during the relaxation period.

[0023] As an optional implementation, the specific process of determining whether the reverse airflow is caused by pressing based on time and flow parameters includes:

[0024] The peak pressure read for the first time is taken as the first peak flow value. After the nth compression, the nth peak flow value is obtained, and the rising speed of the nth peak flow value is extracted, where n is greater than 1.

[0025] When the rising speed is less than the first threshold, it is considered that reverse airflow may be caused by pressing, otherwise the nth peak flow value is discarded;

[0026] Extraction time interval T n , judge T n Whether it exceeds the second threshold, at T n When the peak flow rate is less than the second threshold, it is determined to be invalid and not recorded;

[0027] For the nth peak flow rate value that meets the conditions of rising speed and time interval, determine whether it exceeds the third threshold. When it exceeds the third threshold, it is considered as a valid peak flow rate and the number of presses is counted once.

[0028] As an optional implementation, the specific process of determining the optimal control parameters includes iteratively calculating the optimal proportional, integral, and differential coefficients using the AO-PID control algorithm.

[0029] As an optional embodiment, when performing cardiopulmonary resuscitation, the PWM value is readjusted based on the peak flow value of the reverse airflow caused by compression to complete the flow regulation for the compression period and the relaxation period during the cardiopulmonary resuscitation process.

[0030] As an optional implementation, the peak flow value is extracted to determine whether the reverse airflow is caused by pressing. After determining that the reverse airflow is caused by pressing, the flow zero point position after the reverse airflow is caused by pressing is located, and at the same time, it is determined whether the flow acceleration at this position is greater than 0. The ventilator determines that the zero point position is greater than 0 as the inspiratory phase, and the zero point position is less than 0 as the expiratory phase.

[0031] For the inhalation phase, adjust the PWM value to PWM i =K1*PF / F s ;For the exhalation phase, adjust the PWM value to PWM e =K2*PF / F s ; Among them PWM i and PWM e are the PWM values of the fan in the inspiratory and expiratory phases respectively, K1 and K2 are the gain coefficients, PF is the peak flow value of the reverse airflow caused by the compression, and F is the peak flow value of the reverse airflow caused by the compression. s is the target flow value; PWM in the expiratory phase e When the pressure drops below the set threshold, the pipeline is closed.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] The present invention provides a portable emergency ventilator that automatically identifies the number of chest compressions during CPR based on reverse airflow and simultaneously determines the compression period and relaxation period. The ventilator has a simple structure and a compact size; it has automatic 30:2 ventilation for non-intubated patients and a variable volume ventilation mode suitable for patients with advanced airway establishment, which frees up medical staff, improves emergency treatment efficiency, avoids barotrauma, and is more suitable for emergency treatment during CPR; a new brushless DC motor control method is used to ensure precise control of the ventilator's flow rate.

[0034] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0036] Figure 1 This is a diagram of the structure of a portable emergency ventilator;

[0037] Figure 2 A control process diagram for identifying the number of presses;

[0038] Figure 3 This is a flow chart for volume-controlled ventilation control of a new portable emergency ventilator;

[0039] Figure 4 AO-PID algorithm control process diagram;

[0040] Figure 5 This is a process diagram of variable-level flow control.

[0041] Among them, 1 is a proportional solenoid valve, 2 is a power supply, 3 is a ball valve, 4 is a pressure sensor, 5 is a pipeline, 6 is a flow sensor, 7 is an oxygen sensor, 8 is a microcontroller, 9 is a fan, and 10 is an air-oxygen mixer. DETAILED DESCRIPTION

[0042] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0043] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present invention belongs.

[0044] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0045] like Figure 1 As shown, a portable ventilator suitable for cardiopulmonary resuscitation mainly includes a blower 9, an oxygen sensor 7, an air-oxygen mixer 10, a flow sensor 6, a pipeline 5 and a microcontroller 8. The specific connection relationship and functions of each part are as follows:

[0046] The ventilator's gas power comes from blower 9, which uses a PWM signal for speed regulation to control the outlet flow rate. The blower outlet is connected to an oxygen sensor 7. The air inlet of blower 9 is connected to an air-oxygen mixer 10, which mixes oxygen and air. One end of the air-oxygen mixer 10 is connected to the atmosphere, and the other end is connected to a proportional solenoid valve 1. The proportional solenoid valve inlet is connected to an oxygen source. The other end of the oxygen sensor 7 is connected to the gas inlet of a flow sensor 6, allowing the flow sensor to monitor airway flow in real time. The outlet of the flow sensor 6 is connected to a pipeline 5.

[0047] The pressure sensor 4 is fixed on the pipeline 5 to capture the pressure in the gas circuit in real time.

[0048] Ball valve 3 is connected to the other end of pipe 5 to close the ventilator line. Adding a ball valve to the ventilator line closes the line during compressions to prevent high-pressure injuries, while also preventing the blower from stalling and speeding up the inhalation-expiration switching process.

[0049] The microcontroller 8 is used to receive data from the flow sensor 6 and the pressure sensor 4, and to perform feedback control on the fan to ensure the provision of a constant flow rate.

[0050] The battery module 2 provides the voltage required by the flow sensor 6 and the fan 9, the voltage required by the pressure sensor 4 and the microcontroller 8, and the voltage required by the automatic ball valve, the pressure sensor, and the proportional solenoid valve.

[0051] The voltages of the above devices are not necessarily the same. When the voltages are different, the battery module has multiple corresponding output terminals. The battery module can be made of existing technology or devices, which will not be described in detail here.

[0052] Capturing compression-induced RF automatically achieves 30:2 ventilation. This portable ventilator uses a flow sensor to capture airway flow, determining whether RF is caused by compressions based on time and flow parameters, and counting RF. If an advanced airway is not established, the system automatically reads the number of compressions and automatically initiates ventilation after compressions to achieve a 30:2 ventilation mode.

[0053] During the control process, reverse airflow (RF) caused by compressions is captured to automatically achieve 30:2 ventilation. This portable ventilator uses a flow sensor to capture airway flow, and determines whether RF is caused by compressions based on time and flow parameters, and counts RF. If an advanced airway is not established, the number of compressions is automatically read and ventilation is automatically performed after the compressions are completed, achieving a 30:2 ventilation mode.

[0054] The recognition and counting of RF enables the ventilator to automatically complete 30:2 ventilation. Since compressions cause RF, each RF does not only generate one peak flow. Sometimes a secondary wave will appear after an RF. This algorithm eliminates the interference of the secondary wave on the main wave by the peak flow (Peek flow, PF) size, PF interval time T, and flow increase speed V, and correctly identifies the number of compressions. The compression number recognition scheme is as follows: Figure 2 shown.

[0055] The peak pressure read for the first time is taken as the first PF1 value. After the nth (n>1) press, the system captures the PF n , and extract PF n Ascending speed V n, only V n It is considered to be RF only when it is less than a certain threshold M1, otherwise PF is discarded. n . Then extract the time interval T n , judge T n Whether it exceeds the threshold M2, at T n If it is less than M2, it is considered as invalid PF and will not be recorded. n It is necessary to determine whether it exceeds M3. If it exceeds M3, it is a valid PF and the number of presses is counted by 1. The threshold M1 is set to 1000 ml / s in this embodiment. 2 In this embodiment, threshold M2 is set to 0.3s, and threshold M3 consists of two parts: the average of the previous PFs for less than five compressions and the average of the previous five PFs for more than five compressions. This solution effectively eliminates the complex waves after RF and further accurately obtains the number of compressions.

[0056] Of course, in other embodiments, the setting values of the above threshold parameters can be adjusted according to specific circumstances.

[0057] During the specific control process, it is also necessary to establish a volume ventilation mode of the portable ventilator that is suitable for CPR.

[0058] Volume control ventilation control process of portable emergency ventilator Figure 3 shown.

[0059] The ventilator's flow rate is read by a flow sensor, which feeds the actual flow rate Fr back to the controller. During normal ventilation, the controller compares the actual flow rate Fr with the preset flow rate Fs to achieve real-time control of the PWM value required by the centrifugal fan, thereby adjusting the ventilator's flow rate in real time. During CPR, the PWM controller uses the PF value of RF as input and readjusts the PWM value to adjust the flow rate during the compression and relaxation phases of the CPR process.

[0060] In this embodiment, the PWM control algorithm is divided into an algorithm for normal ventilation in 30:2 mode, such as Figure 4 As shown, and the variable level adjustment algorithm under advanced airway is established, as shown Figure 5 shown.

[0061] The first PWM algorithm discussed in detail is AO-PID, which is the PWM algorithm under 30:2.

[0062] The controller and the PWM controller together form a microcontroller 8 .

[0063] In this embodiment, the fan 9 adopts a micro DC brushless fan, and the AO-PID control method is used to control it in the 30:2 ventilation to achieve accurate control of the pre-reference flow. The AO-PID control algorithm is to add the AO algorithm to the PID algorithm to optimize the three parameters K of PID. p , K i , K d , where K p , K i , K d are the proportional, integral, and differential coefficients respectively. Figure 4 The flow chart showing the AO-PID algorithm is as follows:

[0064] The AO-PID algorithm randomly initializes a PID parameter matrix X, which is shown in Figure 1.

[0065]

[0066] X ij =rand×(UB j -LB j )+LB j ,i=1,2…m,j=1,2,3 (2)

[0067] The elements in the parameter matrix X are randomly generated by formula (2), where UB j and LB j To obtain the upper and lower limits of the parameters, in this embodiment, K p , K i and K d The upper and lower bounds of . rand is a random number.

[0068] The first iteration is performed by

[0069] X1(t+1)=X best (t)(1-t / T)+(X M (t)-X best (t)) (3) ×rand

[0070]

[0071] Among them, X1(t+1) is the solution of the next iteration of t, X best (t) is the best solution obtained before the iteration, and the point average of the current solution at the t-th iteration is X M (t), rand is a random number, dim is the dimension of the question, which is 3 in this embodiment. N is the total number of randomly generated questions m.

[0072] The second iteration is as follows (5)-(12):

[0073] X2(t+1)=X best (t)M(D)+X R (t)+(yx)×rand (5)

[0074]

[0075]

[0076] y=r×cos(θ) (8)

[0077] x=r×sin(θ) (9)

[0078] r=r1+U+D11 (10)

[0079] θ=-ω×D1+θ1 (11)

[0080]

[0081] The iteration t generated in the second step is formula (5), M(D) is the optimal value coefficient, D is the problem dimension, X R (t) is a random value between 1 and N. s is a fixed constant value with a range of up to 0.01. μ and v are random values between 0 and 1, and σ is a fixed constant value with a range of up to 1.5. x and y are used to describe the shape of the path during the search. r1 is a value between 1 and 20 that is used to fix the number of search cycles. U is a variable multiplied by 0.00565, and D1 is an integer from 1 to the maximum value of the search space variable (dim). ω is a small fixed value multiplied by 0.005.

[0082] The third iteration is shown in formula (13):

[0083] X3(t+1)=(X best (t)-X R (t))×α-rand+((UB-LB)×rand+LB×δ (13)

[0084] α and δ are two tuning parameters that are fixed between 0 and 1, and UB and LB represent the upper bound and lower bound for a given problem.

[0085] The fourth iteration is shown in (14)-(17).

[0086] X4(t+1)=Q f X best (t)-G1X(t)-(G1×X(t)×rand)-G2×M(D)+rand×G(14)

[0087]

[0088] G1=2×rand-1 (16)

[0089]

[0090] The solution of the fourth generated iteration is X4(t+1). The quality function used to balance the search strategy is Q f , T is the total number of iterations, t is the current iteration number. G2 decreases from 2 to 0, and rand ranges from 0 to 1.

[0091] After controlling the flow of the normal ventilation ventilator, in order to cope with the special flow and pressure changes during the CPR process of establishing the advanced airway mode, the ventilator needs to use RF to identify the relaxation and compression periods during the compression process, increase the speed of the fan during the relaxation period, and reduce the speed or turn off the fan during the compression period. Figure 5 After ventilation begins, the ventilator extracts the peak PF to determine whether RF is generated. After determining that it is RF, it locates the flow zero point after RF and determines whether the flow acceleration V at that position is greater than 0. If V is greater than 0, the ventilator determines that it is the inspiratory phase. If V is less than 0, the ventilator determines that it is the expiratory phase. For the inspiratory phase, the ventilator adjusts the PWM value to PWM. i =K1*PF / F s ; For the expiratory phase ventilator, adjust the PWM value to PWM e =K2*PF / F s PWM i and PWM e are the fan PWM values for the inspiratory and expiratory phases respectively. K1 and K2 are gain coefficients, PF is the value of the RF, and under normal ventilation conditions, F s is the target flow value. PWM in the expiratory phase e When the pressure is less than the threshold value K3, the ventilator uses a ball valve to close the ventilator airway to prevent stalling, thereby blocking ventilation and reducing the patient's airway pressure to avoid barotrauma.

[0092] like Figure 5 As shown in the figure, the peak flow rate PF is used to determine the occurrence of reverse airflow RF and locate the flow zero point. At the zero point, the flow acceleration V is used to determine the PWM value of the compression and relaxation periods. If the PWM value is too small, the ventilator airway is closed by closing the ball valve, preventing the fan from stalling and accelerating the ventilator response.

[0093] It will be understood by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Thus, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0094] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowcharts and / or block diagrams, as well as combinations of processes and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowcharts and / or block diagrams. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0095] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0096] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0097] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

[0098] Although the above describes the specific embodiments of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without any creative work are still within the scope of protection of the present invention.

Claims

1. A portable ventilator suitable for cardiopulmonary resuscitation, characterized in that: It includes a fan, an air-oxygen mixer, pipes, a controller and a flow sensor, including: The air inlet of the blower is connected to the air-oxygen mixer, and the outlet is connected to one end of the oxygen sensor; The other end of the oxygen sensor is connected to the gas inlet of the flow sensor to monitor the flow rate. The outlet of the flow sensor is connected to a pipeline, and a control switch is provided on the pipeline for closing the pipeline; The pipeline is also provided with a pressure sensor to monitor the gas pressure in the pipeline; The controller communicates with the flow sensor and the pressure sensor, and is used to perform feedback control on the blower based on the monitoring data of the sensors to ensure the provision of a constant flow of gas; The controller is configured to determine whether reverse airflow is caused by compressions based on time and flow parameters during cardiopulmonary resuscitation, count the reverse airflow caused by compressions, read the number of compressions when an advanced airway is not established, and perform ventilation after compressions are completed; The specific process of determining whether reverse airflow is caused by compression using time and flow parameters includes: The peak pressure read for the first time is taken as the first peak flow value. After the nth compression, the nth peak flow value is obtained, and the rising speed of the nth peak flow value is extracted, where n is greater than 1. When the rising speed is less than the first threshold, it is considered that reverse airflow may be caused by pressing, otherwise the nth peak flow value is discarded; Extraction time interval T n , judge T n Whether it exceeds the second threshold, at T n When the peak flow rate is less than the second threshold, it is determined to be invalid and not recorded; For the nth peak flow rate value that meets the conditions of rising speed and time interval, determine whether it exceeds a third threshold value. If it exceeds the third threshold value, it is considered as a valid peak flow rate and the number of presses is counted. The controller is configured to determine optimal control parameters after establishing an advanced airway, complete airway flow control, determine the compression period and relaxation period of chest compression based on reverse airflow caused by compression, reduce or turn off the fan speed during the compression period, and increase the fan speed during the relaxation period; The specific process of determining the optimal control parameters includes using the AO-PID control algorithm to iteratively calculate the optimal proportional, integral, and differential coefficients.

2. A portable ventilator suitable for cardiopulmonary resuscitation as claimed in claim 1, characterized in that: One end of the air-oxygen mixer is connected to the atmosphere, and the other end is connected to a proportional solenoid valve, and an inlet of the proportional solenoid valve is connected to an oxygen source.

3. A portable ventilator suitable for cardiopulmonary resuscitation as claimed in claim 1, characterized in that: The controller is configured to compare the actual flow rate obtained by the flow sensor with the preset flow rate, and adjust the flow rate of the ventilator based on the comparison difference to generate the PWM value required by the fan.

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