What is the medical principle on which the electric shock is based and what does it do

Some studies have shown that the vast majority of cardiac arrests are caused by ventricular fibrillation, 75% occur out of hospital, 20% have no aura, and the likelihood of successful resuscitation decreases by 7% to 10% for every minute that defibrillation is delayed. Defibrillation waveforms include both monophasic and biphasic waveforms, and energy requirements vary between waveforms. Adults with ventricular fibrillation and pulseless ventricular tachycardia should be defibrillated once with 360 joules of energy from a unidirectional wave defibrillator and 120 to 200 joules from a biphasic wave defibrillator. If unfamiliar with defibrillators, 200 joules is recommended as defibrillation energy. Biphasic waveform defibrillation: Early clinical trials have shown that ventricular fibrillation occurring in the prehospital period can be effectively terminated using 150 to 200 J. Low-energy biphasic waves are effective and terminate ventricular fibrillation similarly or more effectively than high-energy monophasic waveform defibrillation. In children, 2 J/kg for the first time and 4 J/kg thereafter. After defibrillation, it generally takes 20 to 30 s to return to normal sinus rhythm, so CPR should be continued immediately after the shock until a carotid artery beat can be palpated. Continuous CPR, correction of hypoxia and acidosis, and intravenous epinephrine (which can be used continuously) can improve the success rate of defibrillation.

The operation steps of defibrillation are: ① electrode plate coated with conductive paste or padded with saline gauze; ② turn on the power to determine the non-synchronous phase discharge, ventricular fibrillation without anesthesia; ③ select the energy level and charging; ④ correctly place the electrode plate according to the requirements, one placed on the right edge of the sternum, between the second and third ribs (the bottom of the heart), and the other one placed in the left anterior axillary line, between the fifth and sixth ribs (the apical part of the heart) (Figure 6); ⑤ by once again After checking the monitored heart rhythm and making it clear that all personnel had not touched the patient (or the bed), the discharge button was pressed; ⑥ Cardiac monitoring and recording was performed immediately after the electric shock.

At present, there are computerized voice prompts to guide the operation of the automatic external defibrillator (automatic external defibrillator, AED), which greatly facilitates the operation of non-professional first aid medical personnel, and buys valuable time for resuscitation. the AED makes the resuscitation success rate increase by 2-3 times, and non-professional rescuers can learn it in 30 minutes. AEDs are indicated for unresponsive, nonrespiratory and noncirculatory signs (including supraventricular tachycardia, ventricular tachycardia and ventricular fibrillation). Public-activated defibrillation (PAD), which requires trained first responders (police, firefighters, etc.) to administer shock defibrillation to a patient in cardiac arrest within 5 minutes using the nearest pre-prepared AED, results in a significant increase in prehospital emergency survival (49%)