Design of wireless distributed medical care system

Design of wireless distributed medical care system

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Source: Electronic Technology Application Author: Wu Li Zhu Yu Cai Bo

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Multi-parameter monitor is an important equipment in clinical care. It can monitor the physiological parameters of patients, such as ECG, blood pressure, blood oxygen saturation, respiratory rate, pulse rate and temperature. Currently, portable monitors with CRT or LCD display are widely used in China. This instrument can display real-time data and waveforms, and has flexible operations, therefore, it is mainly used to assist doctors in diagnosing and analyzing the patient's condition. However, because of its large size and high power consumption (connected to v ac or built-in battery), it is not easy for patients to carry around, and it is impossible to monitor multiple patients at the same time. The wireless distributed medical care system designed in this paper can make up for the above shortcomings. The system uses three independent OEM modules for Physiological Parameter Measurement. Each module is connected to a control display module with wireless transceiver function to form an independent device, therefore, the power consumption and volume of each module are greatly reduced. The patient can select different modules based on different needs. The LCD display on each module can display the measurement signal in real time. All these modules interact with the host machine through wireless information. The PC can register a unique serial number for each module and access the information of each module, this information is stored, analyzed, displayed, and alarm, which facilitates the expansion of many modules, that is, real-time monitoring of multiple patients.
1. system structure and working principle
The system consists of two parts: hardware and software. The hardware mainly includes a PC and three independent modules, namely the ECG module, the blood oxygen module and the blood pressure module. These three modules are composed of the OEM module and the control display transmission module. The ECG module is mainly used to measure parameters such as ECG, respiratory rate, and temperature. The blood oxygen module is mainly used to measure parameters such as blood oxygen saturation and pulse rate. The blood pressure module is used to measure blood pressure parameters. The software part mainly refers to the central monitoring software of the host computer, including the database part and the user interface. Figure 1 shows the structure of the wireless distributed medical monitoring system.

 

In Figure 1, each OEM module communicates with the PC through the wireless transmission module to exchange information. The data collected by each OEM module is stored after being processed on a PC. You can select any module on the central monitoring software interface to view the collected data or waveforms in real time. The software can automatically analyze the data and send an alarm signal when exceptions are detected.
2 functions and features of each module
2.1 control display transmission module
The control and display transmission module is based on the single-chip microcomputer of atmega161, external WGM-12864 graphics LCD module, buttons and wireless transceiver module of nrf903. The circuit structure 2 is shown in.

 

The Atmel-based 8-bit low-power CMOS Proteus microcontroller, developed by ATMEL, features 1 MIPS/MHz performance, 16 K flash, 512-byte EEPROM, and 1 K-byte memory, 35 General I/O Ports, 32 general-purpose registers, three timers, internal and external interrupt sources, two programmable UART ports, SPI ports, and three power-saving modes that can be selected through software.
The WGM-12864B module is a monochrome graphics dot matrix LCD module, the number of dot matrix is 64 × 128. The 8-bit data line is connected to the PA port of the atmega161, and the control line is connected to the high 6-bit PC port. d/I indicates whether the signal on the Data Bus is a dot matrix number or a control command word, r/W indicates that the current operation is a read or write operation, e indicates the enable control side, RST indicates the reset side, and CS1 and CS2 indicates the Left and Right lattice area selection side. PC1, PC2, PB1, and pb0 are the function Selection keys. Together with the LCD, a menu-based interactive interface can be formed to control the corresponding OEM module. In working mode, the LCD displays the relevant data information obtained from the OEM module.
The NRF903 module is a wireless transceiver module. NRF903 is a single-chip wireless transceiver chip launched by NORDIC. It adopts Bluetooth core technology design, A 32-pin chip includes three-Segment High-frequency transmitting, high-frequency receiving, PLL synthesis, I/Q modulation, I/Q demodulation, multi-channel switching, and asynchronous communication interfaces, its programming interfaces include CFG_CLK (configure register clock), CFG_DATA (configure register data), CS (configure register chip selection), and the SPI ports PB7 (SCK) and PB5 (MOSI) of Atmega161 respectively) and PB4 (SS) connections. You can program parameters such as the operating frequency, channel, output power, and output clock frequency. Set CS to a high level. The 14-bit control word from the microcontroller writes the logical value on the CFG_DATA end to the configuration register on the rising edge of the clock signal in each CFG_CLK programming mode, and the programming information is loaded, the parameter settings are complete. STBY and PWR_DWN are connected to the PD6 and PD5 of Atmega161 respectively, and can be set to standby or power-down mode. The DATA interface DATA is connected to a UART1 port of Atmega161 to receive and send DATA. The TXEN script is connected to PD7 to control data sending and receiving.
2.2 ecg oem module
The ecg oem module adopts the BT007 seven-channel electrocardiographic board of Beijing chuangtong yuan Electronic Instrument Co., Ltd. BT007 can automatically measure human body parameters such as ECG wave, respiration wave, heart rate, respiration rate, and temperature. It has the following features: synchronizing seven-channel heartwave and four-level programmable gain, three-Level filtering (diagnosis, monitoring, and operation), qibo pulse suppression, lead shedding alarm, and heart rate range: 20 ~ 250BPM, antifibrillation and electrical knife interference, impedance respiration, respiratory rate range 5 ~ 99BPM; dual temperature measurement, measurement range: 0 ~ 50 °C, display accuracy 0.1 °C, measurement accuracy 0.2 °C. The communication interface with the user is UART serial communication. There are two internal communication protocols: Synchronous three-channel ECG protocol and synchronous seven-channel ECG protocol, which can be selected by jumper. The characteristics of the synchronous three-channel ECG protocol are as follows: 19200 baud rate, 8-bit data, 1 start bit, 1 stop bit, and no parity bit. the characteristics of the synchronous seven-channel ECG protocol are as follows: 28800 baud rate, 8-bit data, 1 start bit, 1 stop bit, no parity bit. The MCU can send control words to the module to control the ECG gain and filtering methods. The data transmitted by the ECG board to the MCU is grouped by one byte data header plus several bytes of data, send messages in groups. The data header is 251 ~ 254, the Data byte is 0 ~ 250. MCU can classify, store, analyze, display, and transmit the data to PC in real time.
2.3 blood oxygen OEM module
The blood oxygen OEM module adopts the digisat pulse oxygen module of Beijing miniso electronic instrument Co., Ltd. This module communicates with MCU through the UART port of TTL level. It provides the following data: arterial oxygen saturation, pulse rate, volume scan chart, bar chart, signal strength and status information. Its communication protocol is compatible with the BCI communication protocol. The Data Transmission baud rate is 4800bps, and the transmission format is: 8-Bit Data + parity bit + 1 stop bit. Each second, 60 data packets are sent to the MCU, each of which is 5 bytes.
2.4 blood pressure OEM module
The blood pressure OEM module adopts the btn602 non-invasive blood pressure measurement module of Beijing miniso electronic instrument Co., Ltd. This module also communicates with MCU through the UART port of the TTL level. After receiving external commands, the system returns the system status and corresponding data. The data format is: start bit + 8-Bit Data bit + 1-bit stop bit, no parity bit, the baud rate is 4800bps.
3. Software System Design-central monitoring software
The software is designed in the VC language. On the premise of combining the previous management systems of the same hospital, the new and old systems are organically integrated in accordance with the principles of unified standards, fully ensuring the independent reliability of the original system, the software structure is modularized and reconstructed. The system requires the Administrator to manually enter the patient information in the computer system and save the key information to the central database server. Then, the Administrator sorts, counts, and classifies the key data in the database. Copy the data to the monitoring center database of each department by category. When the monitoring requirement is enabled, the patient is monitored and recorded. The alarm level of patient monitoring data can be adjusted according to the monitoring needs. During the query, key data and images can be displayed separately, the queried key data can be annotated, images can be annotated, and key data and image files can be printed and output in batches. The software system structure is shown in figure 3.

 

The security control of the system mainly includes three aspects: database security, image file security, and user permission security. SQL Server, a database server established on the NT Server, requires authentication when logging on to the user and database operator. Only accounts and passwords of database users can be used for database management and maintenance. Users have different levels of permissions on different tables. The file server uses port control to control access, ensuring the security of the file server.
The system software collects data from low-end modules through the wireless transceiver module and polling. If the system times out when querying patient information, it skips the module query and enters the query of other modules, the software records the number of failed queries. When the number of failed queries exceeds a certain threshold, the system sends an alarm.
References
1 Li chaoqing. MCU & DSP peripheral digital IC Technical Manual [M]. Beijing: Beijing University of Aeronautics and Astronautics Press, 2003
2. Li xiaojiji. SQL Server 2000 Management and Application System [M]. Beijing: People's post and telecommunications Press, 2002
3 Principle and Application of the High-speed embedded single-chip microcomputer (revised version) [M]. Beijing: Beijing University of Aeronautics and Astronautics Press, 2002