Architecture Proposal for an Automated Biphasic External Defibrillator

摘要

This paper presents a proposal for the electrical architecture of a semiautomated biphasic external defibrillator (AED). This paper shows the functional blocks proposed to integrate a defibrillator and discusses some particular issues. The defibrillator can determine the patient's transthoracic impedance and allows the implementation of an energy correction method that compensates for the transthoracic impedance of the patient, supplying a discharge adjusted to his characteristics. The high voltage block is integrated by three functional units. The first of these determine, based upon the impedance value and the energy selected, the set of voltages required to end the charge of the internal high energy capacitor and to control both phases of the discharge. Besides, it controls the sequence of the process and adds safety to the system. The second functional unit is intended for the generation and monitoring of the voltage on the high energy storage capacitor. Finally, a third unit is used for controlling the discharge path through the patient's thorax switching current with discrete semiconductors. Results testing the high voltage block are presented and discussed. The proposed architecture combines several microcontrollers with special modules for digital signal processing and serial communication between the high voltage block and the rest of the functional blocks, i.e. ECG acquisition module, pulse oximetry, electronic datalogger module, peripheral interfaces (display, buzzer) as well as voice prompts for assisting lay personnel in operating the defibrillator.