基于STM32的自动体外除颤器系统设计与实现

发布时间：2018-10-11 15:32

【摘要】：据统计,我国每年约有50万以上的人猝死于突发性心脏骤停(SCA),医学研究证明,病人若在发生突发性心脏骤停的最初几分钟内接受到电除颤抢救后,存活的机率将大大提高。由于病人发病的不确定性以及所处的场合,所以需要一种便携式,并便于非医护人员操作的除颤器来完成急救工作。自动体外除颤器(Automated External Defibrillator,简称AED)是一种现场急救电除颤设备,可以现场实时采样监测病人的心电,对心电进行实时分析,给出是否需要为病人给予电除颤指示。这种除颤设备缩短了抢救患者的宝贵时间,提高了抢救成功率。本文的主要工作是自动体外除颤器系统的设计与实现,分为以下几点：首先,根据除颤器基本原理,设计了自动体外除颤器系统的整体结构方案,依据该方案,简单描述了系统所要实现各个模块电路的功能需求,并分析了它们之间的关系。从四个方面因素综合考虑,对系统最核心的部分处理器—STM32F429BIT6给出了选择原由。其次,根据系统对各个模块电路的功能需求,分析其电路原理,依次完成了：微控制器最小系统电路、高压充电电路、除颤放电电路、心电信号采集电路、经胸阻抗检测电路、人机交互模块电路、WIFI无线模块接入电路的设计及实现。再次,研究了根据除颤能量计算高压储能电容充电电压的算法、心室纤颤的检测算法。对经胸阻抗检测电路建立等效模型,使用算法解决了AD5933测量小阻抗时精确度低的问题。定时调整除颤放电回路中的内部电阻,克服了除颤电流按指数形式快速下降的问题。完成了系统整体运行,高压充电、双相波除颤放电、经胸阻抗检测等算法的设计流程和软件编程。最后,设计PCB制板图,完成了系统软硬件调试、测试；给出了详细的调试流程,以及系统中关键部分高压充电测试、除颤放电过程测试的详细说明；提出了一种使用示波器测量双相波除颤放电能量的方法。测试结果表明：系统的高压充电电压误差小于3%,除颤双相波电流平稳变化,无尖峰脉冲,除颤能量误差控制在14%以内,满足设计要求。下一步系统需通过动物和临床试验的验证,便可实际应用。
[Abstract]:According to statistics, more than 500000 people in China die of sudden cardiac arrest (SCA),) every year. Medical research shows that if patients receive electrical defibrillation in the first few minutes of sudden cardiac arrest, the probability of survival will be greatly increased. Due to the uncertainty of the patient's onset and the situation, a portable defibrillator is needed to complete the first aid. Automatic external defibrillator (Automated External Defibrillator,) is a kind of field emergency defibrillation device. It can be used to monitor the ECG of patients in real time, analyze the ECG in real time, and give whether it is necessary to give the defibrillation indication for the patients. This defibrillation device shortens the precious time of rescuing patients and improves the success rate. The main work of this paper is the design and implementation of the automatic external defibrillator system, which is divided into the following points: firstly, according to the basic principle of the defibrillator, the whole structure scheme of the automatic external defibrillator system is designed. The functional requirements of each module circuit are briefly described, and the relationship between them is analyzed. Considering the four factors, the selection of STM32F429BIT6, the core processor of the system, is given. Secondly, according to the functional requirements of each module circuit of the system, the principle of the circuit is analyzed, and the minimum system circuit of the microcontroller, the high voltage charging circuit, the defibrillation discharge circuit, the ECG signal acquisition circuit and the transthoracic impedance detection circuit are completed in turn. The design and implementation of man-machine interaction module circuit and WIFI wireless module access circuit. Thirdly, the algorithm of calculating the charging voltage of high voltage energy storage capacitor and the detection algorithm of ventricular fibrillation are studied based on defibrillation energy. The equivalent model of the transthoracic impedance detection circuit is established, and the problem of low accuracy in AD5933 measurement of small impedance is solved by using the algorithm. The internal resistance in the defibrillation discharge loop is adjusted periodically to overcome the problem that the defibrillation current decreases exponentially. The whole operation of the system, high voltage charging, duplex wave defibrillation discharge, transthoracic impedance detection and other algorithm design flow and software programming are completed. Finally, the PCB system board diagram is designed, the system hardware and software debugging and testing are completed, and the detailed debugging flow, the key parts of the system high voltage charging test and defibrillation discharge process testing are described in detail. A method for measuring the energy of dual phase wave defibrillation discharge using oscilloscope is presented. The test results show that the voltage error of the system is less than 3, the defibrillation biphase wave current changes smoothly, there is no spike pulse, and the defibrillation energy error is controlled within 14%, which meets the design requirements. The next step of the system needs to be verified by animal and clinical trials, so it can be applied in practice.
【学位授予单位】：西安邮电大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TH772

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