Sudden cardiac arrest may be treated via attempts at resuscitation. This is usually carried out based upon basic life support, advanced cardiac life support (ACLS), pediatric advanced life support (PALS), or neonatal resuscitation program (NRP) guidelines. CPR training on a mannequin Cardiopulmonary resuscitation Early cardiopulmonary resuscitation (CPR) is essential to surviving cardiac arrest with good neurological function. It is recommended that it be started as soon as possible with minimal interruptions once begun. The components of CPR that make the greatest difference in survival are chest compressions and defibrillating shockable rhythms. After defibrillation, chest compressions should be continued for two minutes before a rhythm check is again done. This is based on a compression rate of 100-120 compressions per minute, a compression depth of 5–6 centimeters into the chest, full chest recoil, and a ventilation rate of 10 breath ventilations per minute. Correctly performed bystander CPR has been shown to increase survival; however, it is performed in less than 30% of out of hospital arrests . If high-quality CPR has not resulted in return of spontaneous circulation and the person's heart rhythm is in asystole, discontinuing CPR and pronouncing the person's death is reasonable after 20 minutes. Exceptions to this include certain cases with hypothermia or who have drowned. Some of these cases should have longer and more sustained CPR until they are nearly normothermic. Longer durations of CPR may be reasonable in those who have cardiac arrest while in hospital. Bystander CPR, by the lay public, before the arrival of EMS also improves outcomes. Either a bag valve mask or an advanced airway may be used to help with breathing particularly since vomiting and regurgitation are common, particularly in out-of-hospital cardiac arrest (OHCA). If this occurs, then modification to existing oropharyngeal suction may be required, such as the use of Suction Assisted Laryngoscopy Airway Decontamination. High levels of oxygen are generally given during CPR. Tracheal intubation has not been found to improve survival rates or neurological outcome in cardiac arrest and in the prehospital environment may worsen it. Endotracheal tube and supraglottic airways appear equally useful. When done by EMS 30 compressions followed by two breaths appear better than continuous chest compressions and breaths being given while compressions are ongoing. For bystanders, CPR which involves only chest compressions results in better outcomes as compared to standard CPR for those who have gone into cardiac arrest due to heart issues. Mouth-to-mouth as a means of providing respirations to the patient has been phased out due to the risk of contracting infectious diseases from the patient. Mechanical chest compressions (as performed by a machine) are no better than chest compressions performed by hand. It is unclear if a few minutes of CPR before defibrillation results in different outcomes than immediate defibrillation. If cardiac arrest occurs after 20 weeks of pregnancy someone should pull or push the uterus to the left during CPR. If a pulse has not returned by four minutes emergency Cesarean section is recommended. Defibrillation An automated external defibrillator stored in a visible orange mural support Defibrillation is indicated if an electric-shockable heart rhythm is present. The two shockable rhythms are ventricular fibrillation and pulseless ventricular tachycardia. In children 2 to 4 J/Kg is recommended. The defibrillation is made by an automated external defibrillator (AED), a portable machine that can be used even by any user because it produces voice instructions that guide the process, automatically checks the victim's condition, and applies the correct electric shocks. Some defibrillators even provide feedback on the quality of CPR compressions, encouraging the lay rescuer to press the person's chest hard enough to circulate blood. In addition, there is increasing use of public access defibrillation. This involves placing an automated external defibrillator in public places, and training staff in these areas how to use them. This allows defibrillation to take place prior to the arrival of emergency services and has been shown to lead to increased chances of survival. It has been shown that those who have arrests in remote locations have worse outcomes following cardiac arrest. Medications Lipid emulsion as used in cardiac arrest due to local anesthetic agents , medications other than epinephrine (adrenaline), while included in guidelines, have not been shown to improve survival to hospital discharge following out-of-hospital cardiac arrest. This includes the use of atropine, lidocaine, and amiodarone. Epinephrine in adults, as of 2019, appears to improve survival but does not appear to improve neurologically normal survival. It is generally recommended every five minutes. Epinephrine acts on the alpha-1 receptor, which in turn increases the blood flow that supplies the heart. This would assist with providing more oxygen to the heart. Based on 2019 guidelines, 1mg of epinephrine may be administered to patients every 3-5 minutes, but doses higher than 1mg epinephrine are not recommended for routine use in cardiac arrest. If the patient has a non-shockable rhythm, the epinephrine should be administered as soon as possible. For a shockable rhythm, epinephrine should only be administered after initial defibrillation attempts have failed. Vasopressin overall does not improve or worsen outcomes compared to epinephrine. The combination of epinephrine, vasopressin, and methylprednisolone appears to improve outcomes. Some of the lack of long-term benefit may be related to delays in epinephrine use. While evidence does not support its use in children, guidelines state its use is reasonable. Lidocaine and amiodarone are also deemed reasonable in children with cardiac arrest who have a shockable rhythm. The general use of sodium bicarbonate or calcium is not recommended. The use of calcium in children has been associated with poor neurological function as well as decreased survival. Correct dosing of medications in children is dependent on weight. To minimize time spent calculating medication doses, the use of a Broselow tape is recommended. The 2010 guidelines from the American Heart Association no longer contain the recommendation for using atropine in pulseless electrical activity and asystole for want of evidence for its use. Neither lidocaine nor amiodarone, in those who continue in ventricular tachycardia or ventricular fibrillation despite defibrillation, improves survival to hospital discharge but both equally improve survival to hospital admission. Thrombolytics when used generally may cause harm but may be of benefit in those with a confirmed pulmonary embolism as the cause of arrest. Evidence for use of naloxone in those with cardiac arrest due to opioids is unclear but it may still be used. In those with cardiac arrest due to local anesthetic, lipid emulsion may be used. Targeted temperature management Current international guidelines suggest cooling adults after cardiac arrest using targeted temperature management (TTM), which was previously known as therapeutic hypothermia. People are typically cooled for a 24-hour period, with a target temperature of . There are a number of methods used to lower the body temperature, such as applying ice packs or cold-water circulating pads directly to the body, or infusing cold saline. This is followed by gradual rewarming over the next 12 to 24 hrs. Effectiveness of TTM after out-of-hospital cardiac arrest is an area of ongoing study. Pre-hospital TTM after out-of-hospital cardiac arrest has been shown to increase the risk of adverse outcomes. The rates of re-arrest may be higher in people who were treated with pre-hospital TTM, however, more research is needed on the effectiveness and risks of TTM. TTM in post-arrest care has not been found to improve mortality or neurological outcomes. Moreover, TTM may have adverse neurological effects in people who survive post cardiac arrest. Do not resuscitate Some people choose to avoid aggressive measures at the end of life. A do not resuscitate order (DNR) in the form of an advance health care directive makes it clear that in the event of cardiac arrest, the person does not wish to receive cardiopulmonary resuscitation. Other directives may be made to stipulate the desire for intubation in the event of respiratory failure or, if comfort measures are all that are desired, by stipulating that healthcare providers should "allow natural death". Chain of survival Several organizations promote the idea of a chain of survival. The chain consists of the following "links": * Early recognition If possible, recognition of illness before the person develops a cardiac arrest will allow the rescuer to prevent its occurrence. Early recognition that a cardiac arrest has occurred is key to survival for every minute a patient stays in cardiac arrest, their chances of survival drop by roughly 10%. * Early CPR improves the flow of blood and of oxygen to vital organs, an essential component of treating a cardiac arrest. In particular, by keeping the brain supplied with oxygenated blood, chances of neurological damage are decreased. * Early defibrillation is effective for the management of ventricular fibrillation and pulseless ventricular tachycardia * Early advanced care * Early post-resuscitation care which may include percutaneous coronary intervention If one or more links in the chain are missing or delayed, then the chances of survival drop significantly. These protocols are often initiated by a code blue, which usually denotes impending or acute onset of cardiac arrest or
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