CN206659797U - CPR aids in Main Control Tank - Google Patents

Abstract

It the utility model is related to medical treatment auxiliary product technical field, Main Control Tank is aided in more particularly, to CPR, the Main Control Tank (2) has hardware Acquisition Circuit (21), signal software processor (22), SIM900A modules (23), OLED LCDs (24) and power unit (25), wherein, shown after the signal analysis and processing that signal software processor gathers to hardware Acquisition Circuit (21) in OLED LCDs (24), synchronous signal software processor also connects SIM900A modules (23) by serial communication interface, the host computer (3) of SIM900A modules (23) wireless connection android system.Relative to prior art, the utility model can provide accurate instruct to the external chest compression of CPR, there are other functions such as rescue flow is shown, GPS location dials 120 ambulance calls, ecg wave form monitoring, the monitoring of blood oxygen waveform, pulses measure, Android product introductions simultaneously, comprehensive monitoring patient health status, so as to greatly improve salvage success rate.

Description

Cardiopulmonary resuscitation auxiliary main control box

technical field

The utility model relates to the technical field of medical auxiliary products, in particular to a cardiopulmonary resuscitation auxiliary main control box.

Background technique

CPR (cardiopulmonary resuscitation) is a necessary technique in the field of emergency medical services, and the life and death of the rescued person (patient) depends on the appropriateness of this technique. When CPR is to be performed, the rescuer compresses the sternum on the upper side of the chest, which replaces the patient's heart, causing oxygenated blood to circulate throughout the living body.

Chest compressions are a key step and a central part of early cardiopulmonary resuscitation for victims of cardiac arrest. Whether a patient can receive timely and effective chest compressions after cardiac arrest has an important impact on the success rate of the patient's treatment. However, according to a large number of clinical medical studies at home and abroad, the effectiveness of chest compressions by most ambulance personnel is not ideal. The compression time is too long, the physical exertion causes the compression to be too shallow, and the compression effect cannot be achieved, or the force is too strong and the compression is too deep. Fracture or even punctured pleura complicated by pneumothorax. Therefore, it is necessary to know the patient's physical condition in time and provide accurate guidance for chest compressions during chest compressions, and can accurately provide devices for positioning to nearby hospitals.

Utility model content

The purpose of the utility model is to provide an auxiliary main control box for cardiopulmonary resuscitation, which can provide accurate guidance for chest compressions for cardiopulmonary resuscitation, and can accurately provide positioning to nearby hospitals to improve the effectiveness of rescue.

In order to achieve the above object, the utility model adopts the following technical solutions:

Cardiopulmonary resuscitation auxiliary main control box, the main control box has a hardware acquisition circuit, a signal software processor, a SIM900A module, an OLED liquid crystal display and a power supply part, wherein the signal software processor analyzes and processes the signal collected by the hardware acquisition circuit on the OLED The LCD screen displays, and at the same time, the signal software processor is also connected to the SIM900A module through the serial port communication interface, and the SIM900A module is wirelessly connected to the upper computer of the Android system.

The hardware acquisition circuit includes a signal preamplification circuit and a high-low pass filter circuit to complete the extraction, filtering and amplification of ECG, blood oxygen and pulse signals.

The signal software processor is a single-chip microcomputer based on the STM32 chip.

The main control box is also attached with a TFT-LCD liquid crystal display module for displaying the first aid process so as to guide the use of the pressing pad. The TFT-LCD liquid crystal display module is controlled by the FSMC module of the signal software processor.

The TFT-LCD liquid crystal display module uses an SD card to store the first aid process, and accesses it through SPI mode or SDIO mode.

The common mode rejection ratio of the signal preamplification circuit is above 80dB.

Compared with the prior art, the utility model can provide accurate guidance for chest compressions of cardiopulmonary resuscitation, and at the same time has rescue process display, GPS positioning to dial 120 emergency calls, ECG waveform monitoring, blood oxygen waveform monitoring, pulse measurement, Android product introduction and other functions to comprehensively monitor the patient's health status, thereby greatly improving the success rate of rescue.

Description of drawings

Accompanying drawing 1 is the structural representation of one embodiment of the utility model;

Accompanying drawing 2 is the circuit diagram of the signal software processor based on the STM32 chip of the main control box;

Accompanying drawing 3 is main control box signal pre-amplification circuit diagram;

Accompanying drawing 4 is the high-pass filter circuit diagram of the main control box;

Accompanying drawing 5 is main control box low-pass filter circuit diagram;

Accompanying drawing 6 is the picture decoding flowchart of the main control box.

detailed description

The conception, specific structure and technical effects of the present utility model will be further described below in conjunction with the accompanying drawings, so as to fully understand the purpose, characteristics and effects of the present utility model.

Referring to Figures 1 to 6, which are structural schematic diagrams of preferred embodiments of the present invention, the utility model relates to a cardiopulmonary resuscitation auxiliary main control box, and the main control box 2 has a hardware acquisition circuit 21, a signal software processor 22, and a SIM900A module 23 , OLED liquid crystal display 24 and power supply part 25 . In this embodiment, the signal software processor 22 is a single-chip microcomputer based on the STM32 chip. The signal software processor 22 analyzes and processes the signal collected by the hardware acquisition circuit 21 and displays it on the OLED liquid crystal display screen 24. At the same time, the signal software processor is also connected to the SIM900A module 23 through the serial port communication interface, and the SIM900A module 23 is wirelessly connected to the host computer 3 of the Android system After receiving the location information on the main control box 2, the upper computer 3 of the Android system performs positioning and searches for nearby products.

The main control box 2 completes the extraction, filtering and amplification of ECG, blood oxygen and pulse signals, and performs analog to digital conversion of signals, digital filtering processing of signals, signal analysis and waveform display on the LCD screen. Furthermore, the hardware acquisition circuit 21 in the main control box 2 includes a signal preamplification circuit 211 and a high-low pass filter circuit 212 to complete the extraction, filtering and amplification of ECG, blood oxygen and pulse signals. The common mode rejection ratio of the signal preamplification circuit 211 is above 80dB. The main control box 2 is also provided with a TFT-LCD liquid crystal display module 26 for first aid process display to guide the use of the pressing pad. The TFT-LCD liquid crystal display module 26 is controlled by the FSMC module based on the signal software processor 22 of the STM32 chip. . The TFT-LCD liquid crystal display module 26 uses an SD card to store the first aid process, and accesses it through SPI mode or SDIO mode. The utility model concrete work is as follows:

As shown in Figures 1 and 2, the signal software processor 22 uses the STM32F1 chip of the Cortex-M3 core, and the operating frequency is 8MHZ. The chip has an ARM 32-bit Cortex-M3 CPU, 128k flash on the chip, 20kRAM, and a 12-bit precision chip. The internal ADC converter, as well as peripherals such as I2C interface, can complete signal acquisition and data filtering operations on a simple circuit. The output signal of the electrocardiogram electrode sheet is conditioned and collected by the AD converter of the STM32 microcontroller. The sampling of the analog signal uses the ADC1 channel, the time interval between two samplings is 14 clock cycles, and the conversion accuracy is 12bit. The trigger clock of the ADC is configured as TIM2 output, and the data transmission from the peripheral to the memory is carried out through DMA, and the DMA ping-pong structure is used for Data storage and processing.

The display process uses TFT-LCD liquid crystal, and the FSMC module of STM32 is used to control the liquid crystal. FSMC is a flexible static memory controller, which can interface with synchronous or asynchronous memory and 16bit PC memory card. Its major feature is the programmable timing of accessing external devices: programmable waiting period, programmable bus recovery period, output Enable and write enable delays are programmable, independent of read and write timing and protocol. In this way, the liquid crystal can be used as an external storage device, and the read and write and control signal timings are configured, and the read and write access to the liquid crystal can be realized as long as the pointer is specified. In this way, firstly, it simplifies the operation of the LCD, and the operation can be completed only by specifying the pointer for reading and writing data. Second, it improves the access speed, and avoids the phenomenon of "pull the screen" caused by using the port to simulate the timing to access the LCD.

SD card has the advantages of large storage capacity, low cost, and fast read and write speed, and is gradually becoming the mainstream of storage devices. There are two access modes: SPI mode and SDIO mode. STM32 has interfaces for both modes.

As shown in Figure 6, the first aid process is vividly expressed in the form of a hand-drawn drawing, which is stored in the SD card. When starting up, it first detects the font library, checks whether the SD card exists, reads the picture, decodes it, uses FSMC to access the LCD screen and displayed on the LCD screen.

The SIM900A module 23 is connected with the signal software processor 22 based on the STM32 chip through a serial port. As the core control system, the signal software processor 22 uses the function of SIM900A to send short messages. TRXD and SRXD are the data communication ports of SIM900A. The AT commands and data we send by default are all through these two ports. In addition, STXD and SRXD have done compatibility processing, and support LVTTL level (ie 3.3V/5V) microcontroller system, you can directly connect STXD and SRXD to the corresponding pins of the microcontroller system to achieve communication. This embodiment adopts the UART serial port communication method, so it is necessary to connect the ports STXD, SRXD and the IO ports PA10 (USR0_RX) and PA9 (USR0_TX) of the MCU respectively to realize communication with SIM900A (baud rate is 115200); the module is powered by 5V, Common ground with the second signal software processor 22 .

The ECG signal is a direct signal, the source is the heart, and it is an approximately periodic signal with strong mutations. It is a very typical biomedical signal with obvious time-frequency characteristics and time-scale characteristics. We use electrode sheets to extract the ECG signal. After testing, we know that in the time domain, due to the existence of interference factors, the ECG signal always fluctuates within a certain range, and the amplitude of the signal is very small, generally only 0.05-5mV , with an average value of 1 μV, which is easily overwhelmed by the influence of myoelectric interference caused by skin potential or baseline drift caused by polarization voltage, which brings difficulties to the detection of signals.

In the frequency domain, the frequency of the human ECG signal is relatively low, and the DC component accounts for a high proportion of the ECG signal. After filtering the DC component, the frequency is mainly concentrated in 0.05-100Hz, and most of the energy is concentrated in 0.05-40Hz. Within the range, it can also be seen from the power spectrum that during the QRS period where most of the energy of the ECG signal is concentrated, the peak frequency of this period is generally between 10-20Hz. The detection of the QRS waveform becomes easily identifiable as it is very evident throughout the ECG map.

The hardware acquisition circuit 21 is divided into components such as a power supply circuit, a signal preamplification circuit 211 , and a high-low pass filter circuit 212 . Among them, the power supply part adopts a 3.7V lithium battery + LDO low-dropout linear regulator output voltage for the analog part circuit and the digital part circuit. The signal pre-amplification circuit 211 mainly acquires the raw data of the electrode sheet and performs 1000 times amplification processing. The high- and low-pass filter circuit 212 is equipped with high-pass and low-pass filters to filter out part of the baseline drift, suppress myoelectric interference, filter out power frequency interference, and then inject the output level into the AD analog channel of the main control circuit. The signal software processor 22 based on the STM32 chip includes 12bit ADC and DMA transmission, and is responsible for digitizing the analog signal and displaying the ECG waveform on the OLED liquid crystal display 24 .

The frequency of the body surface ECG signal is mainly concentrated in 0.05-100Hz, the amplitude is 10μV-4mV, and the typical value is 1mV, which is a weak bipolar signal with low frequency. The ADC input voltage range of STM32 is 0-3.13V, so it is necessary to amplify and level-up the ECG signal. The overall magnification is about 1000 times, and then it is raised by about 1V through the level-up circuit. In ECG measurement, the actual electrodes cannot be completely symmetrical, which will cause baseline drift, as well as ubiquitous power frequency interference (50Hz), myoelectric interference, etc., all of which require the ECG preamplifier must have Very high common-mode rejection ratio. Generally, the common mode rejection ratio is required to be above 80dB. As shown in Figure 3, the present embodiment selects AD8232 as the system preamplifier, which has the characteristics of low noise, low drift, high common-mode rejection ratio, high input impedance, etc., and its gain can reach 1000 times, and the calculation formula is G= 1+50k/Rg. The maximum electrode polarization voltage can reach 300mV. In order to prevent the preamplifier from entering the cut-off or saturation state, its amplification factor must be limited. Here, the gain is 10, and Rg=516kΩ is obtained from G=1+50/Rg. The external resistor Rg is selected as a resistor Precision wirewound resistors with a value of 516kΩ. Since the impedance of the human body and the impedance of the ECG electrode are very large, a first-stage follower is designed as a signal buffer before the preamplification. In order to suppress 5Hz interference better, the electrode on the right leg is connected to the ground terminal of the amplifier through a resistor to reduce the common-mode voltage of the human body.

The frequency band of the ECG signal is mainly concentrated in 0.05-100Hz, so the bandwidth of the band-pass filter is designed to be 0.03-110Hz to filter out the interference signal. The band-pass filter is composed of high- and low-pass filters, as shown in Figures 4 and 5. Based on miniaturization and cost considerations, hardware filtering only uses a first-order high-pass filter and a first-order low-pass filter. Although the right leg drive circuit is designed , but there is still 50Hz interference entering the circuit, and then use the software method to filter out the 50Hz power frequency interference by designing a digital filter. Frequency interference, but it can be filtered out by software design.

The double-pole high-pass filter circuit in Figure 4 is composed of R1, C1, R2, and C2, and its cut-off frequency is Set its cut-off frequency f _H =0.03Hz; the double-pole low-pass filter circuit in Figure 5 is composed of R1, C1, R2, and C2, and its cut-off frequency is Set its cut-off frequency as f _L =110Hz. The main amplifier circuit should be enlarged by about 100 times. From the waveform processed by the ECG acquisition circuit, it can be seen that the ECG waveform collected by the oscilloscope is relatively clean and conforms to the characteristics of the ECG waveform. At the same time, it can be seen that the waveform still has some ripples, that is, 50Hz interference Existence, these interferences can be eliminated by software filtering.

In a pulse oximeter, the oxygen content in human blood is judged by measuring pulse oxygen saturation (SpO ₂ ). The calculation of _SpO2 is based on the measurement of light intensity attenuated by human tissue, which is defined as the concentration of oxygenated hemoglobin in the tissue The ratio of total hemoglobin (oxygenated hemoglobin and deoxygenated hemoglobin, deoxygenated hemoglobin is reduced hemoglobin) concentration

in, CHb represents the concentrations of oxyhemoglobin and reduced _hemoglobin in human tissues, respectively. The nature of body tissue absorbing different amounts of light depending on the oxygen content level of its blood is nonlinear. Using two different wavelengths of light to alternately illuminate the pulse, the following empirical formula can be used to calculate blood oxygen saturation: SpO ₂ =A·Iλ1AC/Iλ1DCIλ2AC/Iλ2DC－B where A and B are empirical constants, IAC is the pulsating component of the transmitted light intensity, IDC is the non-pulsating component of the transmitted light intensity, and λ1 and λ2 are the wavelengths of the incident light.

STM32 connects two dual-wavelength LED lights connected back to back, which are red light with a wavelength of 660nm and infrared light with a wavelength of 940nm. The photodiode generates current from the received light. The current signal is amplified by a transimpedance amplifier and converted into a voltage signal. The signal consists of a large DC part and a small AC part, of which the AC part is a useful signal. Since the useful signal is relatively weak, the AC signal needs to be extracted and amplified by three operational amplifiers. The extracted and amplified signal is collected by the A/D converter included in the STM32 microcontroller, converted into a digital signal, and then processed by the STM32 to obtain a continuous and stable pulse oximeter signal that varies with light intensity.

The optical signal is converted into an electrical signal by a photodiode, and the current signal is very weak and is easily affected by interference and noise, so the first-stage amplification requires a well-designed low-noise preamplifier circuit to amplify the weak current to drive the subsequent circuit Work. This design uses AD795 as the preamplifier. Its main performance is: at 25°C, the low input bias current is up to 1pA, the low power consumption is up to 1.5mA, and the low input voltage noise is 11nV·Hz at 10kHz.

The second stage of amplification mainly adopts differential amplification. In order to further improve the common mode rejection ratio, a two-stage parallel positive and negative amplifier circuit and a first-stage differential amplifier circuit are used. TL082 is selected as the two-stage parallel positive and negative amplifier circuit. Its main performances are: low offset voltage 15mV, low power consumption 3.6mA, low input voltage noise 16nV Hz, wide common mode, especially suitable for synchronous and inverting amplifier circuits, It meets the requirements of the positive and negative amplifier circuit of this design.

The STM32 MCU selected for data acquisition has two built-in advanced 12-bit analog/digital conversion modules (ADC), with the fastest conversion time of 1 μs. This ADC module also has a self-checking function, which can improve conversion accuracy when environmental conditions change. The STM32 single-chip microcomputer has a higher resolution, and the pulse oximeter signal can reach 101-102mV after two-stage amplification, which has met the conditions for STM32 acquisition.

There are three main traditional pulse measurement methods: one is to extract from the ECG signal; the other is to calculate the pulse rate from the fluctuation measured by the pressure sensor when measuring blood pressure; the third is to use the photoelectric volume method. The first two extraction signals will limit the patient's movement, and if used for a long time, it will increase the patient's physical and psychological discomfort. Therefore, this product uses photoplethysmography for pulse measurement. Pulse measurement is performed by using the difference in light transmittance caused by human tissue when the blood vessels are pulsating. Using a sensor composed of a light source and a photoelectric transducer, when the patient's finger touches the light source, the light beam passes through the peripheral blood vessels of the human body. The light transmittance of the beam of light changes, and at this time, the light reflected by the human tissue is received by the photoelectric converter, converted into an electrical signal, and amplified and output. The low-pass filter and the amplifier composed of the operational amplifier MCP6001 amplify the signal by 330 times, and at the same time use the voltage dividing resistor to set the DC bias voltage to 1/2 of the power supply voltage, so that the amplified signal can be well collected by the single-chip AD.

Most of the upper computer 3 of the Android system has a GPS module, through which we can obtain the current location. This function is mainly used to send information with the current location and map when a crisis occurs, which is important for timely rescue.

Main processing:

1. Jump to the intent to open the GPS page

2. Instantiate LocationManager to open GPS

3. The best search conditions

4. Get the last obtained position

5. Request real-time update of Location data

GPS and network usage permissions, SMS usage permissions, etc. are used, and the lack of any of these permissions can cause the lack of a certain function, or even the software cannot run. The upper computer 3 of the Android system comes with product instructions, rescue process introduction and the function of finding nearby products.

The utility model is a cardiopulmonary resuscitation first-aid product placed in public places, which is used for rescuing patients who have drowning, electric shock, suffocation and other emergencies, and helping rescuers who are not professional medical personnel to calmly face emergencies According to the guidance, timely and active cardiopulmonary resuscitation operations are performed on patients, thereby greatly increasing the success rate of rescue, gaining time for rescue, and rescuing patients who are dying.

After testing, the utility model has the following properties:

1. It takes less than 20s from pressing the call for help button to receiving the emergency alarm message;

2. The picture process shows that the time required to scan a picture is less than 3s;

3. The time required for ECG, blood oxygen and pulse collection is less than 15s;

4. The error between the displayed waveform of ECG and blood oxygen and the waveform displayed by the oximeter of the hospital electrocardiogram is within 5%;

5. Pulse calculation error is controlled within 5%.

The picture process of the host computer of the Android system shows that it takes less than 1 second to scan a picture, and the error between the displayed positioning and the actual positioning of nearby products is within 5%.

Thus, the technical solution of the utility model has the following effects:

a. Rescue process display, the rescue process is played on the LCD screen in the form of hand-painted pictures and animations, which is concise and intuitive, and comes with voice reminders, which can effectively guide non-professional medical personnel to rescuers positively and correctly;

b. It can monitor the patient's ECG and display the ECG signal in the form of a waveform. During cardiopulmonary resuscitation, if each compression is effective, the carotid artery will pulsate once, and the ECG waveform will have a peak. If the pulsation stops after the compression is stopped, it proves that compressions are still needed. If the pulsation continues, it means that the spontaneous heartbeat has recovered and can be stopped. press. The display of the ECG waveform can provide a visual indication of the results of cardiopulmonary resuscitation;

c. It can monitor the patient's blood oxygen and display the blood oxygen signal in waveform form in real time. By comparing the waveform of the normal blood oxygen signal on the large screen on the main control board, it can be judged whether the blood oxygen of the patient is normal;

d. It can monitor the patient's pulse and display the pulse signal in digital form in real time. Whether the patient's pulse is normal can be judged by comparing the waveform of the normal pulse signal on the large screen on the main control board. The product is placed in a public place, and other people who do not need rescue and are prone to dizziness can also use it to monitor physiological indicators and prevent related diseases;

e. When someone needs to be rescued, the rescuer presses the button on the lower left of the main control box to locate the alarm 120, and the patient's location information will be automatically sent to the nearest hospital to notify the hospital for timely rescue.

Other humanized designs:

a. Use 0.96-inch OLED12864 to display heart rate, blood oxygen waveform, pulse value, pixel self-luminous display, low power consumption and clear display;

b. APP product use introduction and process introduction;

c. Positioning, looking for nearby products.

Of course, the utility model has been described in detail above in conjunction with the embodiment, only to illustrate the technical concept and characteristics of the utility model, and its purpose is to let people familiar with this technology understand the content of the utility model and implement it. Equivalent changes or modifications made by the spirit of the present utility model shall be covered within the protection scope of the present utility model.

Claims (6)

1. Cardiopulmonary resuscitation assists master control case, its characterized in that: the main control box (2) is provided with a hardware acquisition circuit (21), a signal software processor (22), an SIM900A module (23), an OLED liquid crystal display screen (24) and a power supply part (25), wherein the signal software processor analyzes and processes signals acquired by the hardware acquisition circuit (21) and displays the signals on the OLED liquid crystal display screen (24), meanwhile, the signal software processor is connected with the SIM900A module (23) through a serial port communication interface, and the SIM900A module (23) is wirelessly connected with an upper computer (3) of an Android system.

2. The cardiopulmonary resuscitation assistance master control box of claim 1, wherein: the hardware acquisition circuit (21) comprises a signal preamplification circuit (211) and a high-low pass filter circuit (212) to complete extraction, filtering and amplification of electrocardio, blood oxygen and pulse signals.

3. The cardiopulmonary resuscitation assistance master control box of claim 1, wherein: the signal software processor (22) is a single chip microcomputer constructed based on an STM32 chip.

4. The cardiopulmonary resuscitation assistance master control box of claim 1, wherein: the main control box (2) is also attached with a TFT-LCD liquid crystal display module (26) for displaying emergency procedures so as to guide the use of the pressing pad, and the TFT-LCD liquid crystal display module (26) is controlled by an FSMC module of the signal software processor (22).

5. The cardiopulmonary resuscitation assistance master control box of claim 4, wherein: the TFT-LCD liquid crystal display module (26) adopts an SD card to store an emergency procedure and accesses through an SPI mode or an SDIO mode.

6. The cardiopulmonary resuscitation assistance master control box of claim 2, wherein: the common mode rejection ratio of the signal preamplification circuit (211) is more than 80 dB.