Cardiopulmonary resuscitation (CPR) techniques were developed in the 1960s, and with the popularization of CPR knowledge and training in first aid techniques, the success rate of resuscitation has been increasing over the past 40 years. About 50% of cardiac arrests occur outside of the hospital, so out-of-hospital resuscitation is very important and the public should be trained in CPR, and public participation in defibrillation is advocated. About 20-40% of patients who survive resuscitation may have permanent neurological disability. In recent years, special emphasis has been placed on strengthening the prevention and treatment of cerebral ischemia and reperfusion injury during CPR. The survival chain of adults is composed of four “early”, that is, early access to the emergency system, early primary CPR, early defibrillation, and early advanced CPR. Primary cardiopulmonary resuscitation Primary cardiopulmonary resuscitation refers to supporting basic vital activities and rapidly restoring blood and oxygen supply to vital organs. It includes rapid identification and measures to prevent circulatory and respiratory arrest in patients with myocardial infarction and stroke, life-saving breathing for respiratory arrest, life-saving breathing and chest compressions for cardiac and respiratory arrest, defibrillation of patients with ventricular fibrillation and ventricular tachycardia with an automated external defibrillator, and identification and removal of airway obstruction. In recent years, special emphasis has been placed on activating the EMS system at the time of primary CPR. Once an adult patient greater than or equal to 18 years of age with loss of consciousness is encountered, the first step should be to call (phone first) to activate the EMS system. However, adults in respiratory and cardiac arrest due to drowning, trauma and drug overdose should call CPR first and then call (phone fast) as soon as possible. The EMT system allows for more effective treatment of the patient. Opening the airway remains the primary measure of CPR. Foreign bodies in the airway are a rare but preventable cause of cardiac arrest. Once the airway is opened, it should be followed by removal of the airway foreign body. If normal breathing is not found, immediate life-saving breathing should be performed. Mouth-to-mouth or mouth-to-nose breathing can be performed. If there is a life-saving respiratory shield device (spacer device, mask) can be used to mouth to shield device breathing. The conditions are available mask or simple respirator for life-saving breathing. Trained lifeguards can use airway assist devices. Pulse checks have been overemphasized in previous CPR guidelines. The specificity of the pulse test is only 90%. There is a 10% chance that a patient without a pulse will be misclassified as having a pulse, thus delaying treatment. For this reason, lifeguards in the field no longer require pulse checks. The correct approach is to give two life-saving breaths to unconscious, non-breathing patients, then determine the signs of circulation (listen, look, feel for normal breathing or coughing, and quickly check for activity), and if there are no such signs, immediately apply chest compressions. Health care workers still require to check the pulse and circulatory signs, the judgment time is no more than 10 seconds. Chest compressions should pay attention to the correct position and posture of the hand during chest compressions, to use the correct method of compressions, such as the following compressions and relaxation time requirements are the same, 50% each, compression frequency should be 100 times / min, whether single or double resuscitation, compressions and life-saving breathing ratio of 15:2. The sequence of primary cardiopulmonary resuscitation using ABC, but also some countries use CAB, the results of the two are not significantly different. However, there is no direct comparison for humans. If mouth-to-mouth ventilation is not desired or available, guidelines state that CPR with compressions alone can also be performed. Because most nontraumatic cardiac arrests are due to ventricular fibrillation, survival from defibrillation decreases by 7% to 10% per minute of delay. Therefore, defibrillation was included in primary CPR for the first time in the 2000 International CPR Guidelines. Defibrillation by the public can reduce defibrillation time to 3-5 minutes. Public defibrillation is the greatest advance in the treatment of prehospital sudden cardiac death since the invention of cardiopulmonary resuscitation. Personnel who should have primary CPR and automated external defibrillators (AEDs) include police officers, firefighters, security personnel, sports instructors, ski patrolmen, shipping staff, airline personnel, and family members and friends of high-risk patients. AEDs should be placed in airports, airplanes, casinos, public buildings, integrated businesses, shopping malls, golf courses, and other public places. II. Advanced CPR Advanced CPR refers to further life support, which includes continued primary CPR, defibrillation, oxygenation, assisted devices for ventilation and airway support, circulatory assist devices, medication, and post-resuscitation treatment. Rapid defibrillation is a major determinant of survival in patients with ventricular fibrillation. Blind defibrillation” was advocated earlier to buy time, but nowadays all defibrillators are equipped with ECG monitoring devices and blind defibrillation is no longer necessary. The use of electrode plates is recommended to identify the nature of syncope. Automatic external defibrillators automatically analyze arrhythmias and identify ventricular fibrillation, making operation easier. Ventricular fibrillation can start with 200 joules, and if one shock is ineffective, another shock should be delivered within a short period of time (within 3 minutes) with the same energy or increased energy (200-300 joules), and a third shock can be delivered with 360 joules. Monomorphic ventricular tachycardia, with or without a pulse, starts with 100 joules. In 1996, the US FDA approved biphasic defibrillation for AEDs. 150 J of biphasic first defibrillation is equivalent to 200 J of unidirectional defibrillation. There is no consensus on the amount of power for biphasic wave defibrillation, which can be used with or without an increase in power. In cardiopulmonary emergencies, oxygen should be administered immediately as an aid, and 100% oxygen should be inhaled. Aids to ventilation include masks, balloon-valve devices (simple ventilators), automatic delivery ventilators, oxygen-driven-manual ventilators, and airway support devices (oropharyngeal and nasopharyngeal airways and tracheal intubation). Adjuncts to manual circulation include intermittent abdominal compression CPR, high frequency CPR (chest compressions at a frequency greater than 100 compressions/min), compressions with active chest expansion CPR, CPR undershirt, mechanical CPR, simultaneous ventilation compressions, phasic chest and abdominal compressions with chest expansion, open heart compressions, and cardiopulmonary diversion. These alternative techniques require additional personnel, training, and equipment compared to regular CPR. By implementing these techniques, antegrade blood flow can be increased by 20 to 100% in CPR (but still well below normal cardiac output). Currently, these techniques are still limited to in-hospital applications and are less effective when applied late in resuscitation or after failed advanced CPR. There is no data to show that these techniques are better than ordinary CPR in pre-hospital primary CPR. Third, the advanced CPR drug therapy 1, the route of drug administration can choose intravenous, endotracheal and intracardiac. Peripheral vein is only available in anterior elbow vein or external jugular vein. When peripheral vein is administered, the peak drug is lower than central vein and the circulation time is longer. In order to make the drug reach the central circulation as soon as possible, the following methods can be used: projectile rapid push, flush with 20 ml of fluid and elevate that side of the limb for 10-20 seconds or intubate to the central circulation for direct drug administration. The central vein can be chosen from the internal jugular vein, subclavian vein, and femoral vein. The internal jugular and subclavian veins, which are closest to the central circulation, have more complications and require the cessation of CPR. The femoral vein is easy to puncture and has fewer complications, but is farther from the central circulation and requires insertion of a long catheter. Endotracheal administration has limitations such as few drug types administered and the inability to administer drugs repeatedly. Intracardiac injection can only be used when intravenous and endotracheal routes are not available. 2.Anti-arrhythmic For tachyarrhythmias with hemodynamic instability, electrical resuscitation should be considered first. In hemodynamically stable cases, drugs should be selected on the basis of further identification of their nature. Wide QRS tachycardia that is hemodynamically stable should be diagnosed as clearly as possible based on history, 12-lead ECG, and esophageal ECG. Procaine amide or amiodarone may be used empirically when a clear diagnosis is not possible, and only amiodarone may be used when there is cardiac impairment. Ventricular tachycardia that is hemodynamically stable can be started with intravenous procaine amide, sotalol, amiodarone, or beta blockers. Lidocaine is relatively ineffective in terminating ventricular tachycardia. Amiodarone is preferred in cardiac insufficiency, and electrical resuscitation can also be used directly. Polymorphic ventricular tachycardia is often hemodynamically unstable and can degenerate into ventricular fibrillation. In hemodynamically stable patients, the presence of QT interval prolongation should be further identified. For tip-twisting ventricular tachycardia due to prolonged QT interval, drugs that cause QT prolongation should be stopped and electrolyte disturbances should be corrected. Intravenous magnesium, temporary pacing, isoprenaline, b-blockers (as an adjunct to temporary pacing), and lidocaine may also be used. Ventricular tachycardia without QT interval prolongation is treated etiologically first, and b-blockers or lidocaine may be used if ischemia is present. In other cases, intravenous amiodarone, lidocaine, procainamide, sotalol, or b-blockers may be used. Ventricular fibrillation/pulseless ventricular tachycardia should be defibrillated first 3 times, and those who cannot be converted or cannot maintain stable perfusion should be defibrillated once more after improving ventilation by applying respiratory assistance facilities such as tracheal intubation and applying measures such as epinephrine and pressin. If still unsuccessful, the effect of electrical defibrillation can be improved with antiarrhythmic drugs, with amiodarone preferred and lidocaine and magnesium also being used. Ventricular fibrillation or pulseless ventricular tachycardia with unsuccessful defibrillation has been shown to improve the outcome of electrical defibrillation with amiodarone as the first choice after epinephrine. Amiodarone has been shown to restore voluntary circulation and improve hospital survival. A randomized comparison of amiodarone with lidocaine showed that amiodarone had a higher success rate of resuscitation. Randomized comparison of lidocaine versus epinephrine showed a higher incidence of arrest in the lidocaine group, with no difference in restoration of voluntary circulation between the two. Prophylactic application of lidocaine in patients with acute myocardial infarction increased mortality rather than benefit. Therefore, the 2004 AHA/ACC guidelines for acute myocardial infarction no longer recommend the use of lidocaine in ventricular fibrillation resuscitation. Immediate electrical cardioversion is also indicated in hemodynamically unstable rapid atrial fibrillation or atrial flutter, regardless of duration. Rapid atrial fibrillation or atrial flutter that is hemodynamically stable can be controlled with drugs to control the ventricular rate. For normal cardiac function, b-blockers, calcium antagonists, or digoxin may be used. Intravenous amiodarone may be considered when conventional ventricular rate control measures are ineffective or contraindicated.