Chain of Survival
The term Chain of Survival provides a helpful metaphor for the Emergency Cardiovascular Care systems concept elements. When the Chain of Survival was first created, it included early recognition, early access, CPR, ventricular fibrillation and ventricular tachycardia defibrillation, and advanced cardiac life support.
This concept was later adopted by the American Heart Association and other health organizations like International Liaison Committee on Resuscitation. Afterward, the Chain of Survival was reevaluated to emphasize the importance of early recognition and response. As aftercare options expanded to include mild therapeutic hypothermia and other treatments, post-cardiac arrest care was added to the Chain of Survival.
Today's latest version includes the recovery link, which emphasizes out-of-hospital cardiac arrest patients and their caregivers' physical, social, and emotional needs after survivors leave the hospital.
Out-of-Hospital Chain of Survival Steps
The Chain of Survival refers to the crucial actions required to treat medical emergencies such as heart attack, out-of-hospital cardiac arrest, stroke, and choking or foreign body airway obstruction. The links in the American Heart Association Chain of Survival are:
- Immediate recognition of out-of-hospital cardiac arrest event and activation of the emergency medical response system
- Early, high-quality CPR
- Rapid defibrillation
- Effective, advanced life support
- Integrated post-cardiac arrest care.
The goal of an out-of-hospital cardiac arrest event is to restore a healthy heart rhythm and good neurological outcome. Bystanders can help save a cardiac arrest victim's life and improve patient outcomes by addressing the first three links in the AHA Chain of Survival. Action steps that bystanders can follow are explained below.
Prevention for Pediatric Patient
Prevention has become very effective in hospitals. Therefore, the American Heart Association recommends mirroring that works in adult care. For pediatrics, prevention measures include safety initiatives. These address specific issues that affect children—for example, bicycle helmet laws and SIDS prevention. The goal is to increase bystander rescuer capacity. As a result, we can decrease emergency response times for children ahead of any actual emergency.
Immediate Recognition and Emergency Response Activation
The Chain of Survival is based on a significant fact: Every minute a person does not receive care after a sudden cardiac arrest event, their chance of surviving decreases. Therefore, lay rescuers and emergency medical services must aim to have the fastest possible response. If you are on the scene, you must recognize the cardiac arrest as it occurs and ask another bystander to call 911 before taking any other rescue steps.
Unfortunately, many persons experiencing symptoms that may lead to out-of-hospital cardiac arrest ignore these warning symptoms or, recognizing these warning symptoms correctly, fail to activate the EMS system, preferring to contact relatives instead.
Early, High-Quality CPR
The immediate initiation of bystander CPR can quadruple the chances of survival from an out-of-hospital cardiac arrest event. If untrained, a bystander can perform Hands-only CPR or chest compressions-only CPR.
One of the most commonly held misconceptions about CPR is the idea that there must be at least two breaths between each compression. More than two breaths aren't much help. Therefore, it's much more important that public access defibrillation must be used as soon as possible.
Rescuers should start CPR immediately, with an emphasis on chest compression. Compressing the chest must be performed fast and hard enough.
According to the American Heart Association, the primary components of high-quality CPR are:
- The adequate chest compression depth for adults and children is 2-2.4, and 1.5 for infants.
- The optimal chest compression rate is 100-120 compressions per minute.
- Minimizing interruptions in CPR. If you're slowing down, switch with a fresh rescuer.
- Allowing full chest recoil between compressions
- Avoiding excessive ventilation (rescue breathing)
Early, rapid defibrillation is a critical link in the out-of-hospital chain of survival. It involves applying an automated external defibrillator (AED) to a person who is not breathing normally and whose heart rhythm is irregular. Public access defibrillation is used to restore normal heart rhythm and blood flow. If the heart stops beating, the AED delivers a powerful electric current through the chest wall to start the heart beating again, increasing the chances of survival. Defibrillation within 3–5 mins of collapse can produce a survival rate as high as 50–70%. So if public access defibrillation is available, rescuers must use it as soon as possible.
Advanced Life Support by Healthcare Providers
By this phase, medical professionals have taken over medical care, and advanced care will be provided. Advanced Life Support is a set of life-saving protocols and skills that extend Basic Life Support to further support circulation, airway, and adequate ventilation. Paramedics staff and other healthcare professionals are considered Advanced Life Support trained, including advanced scene management and medical care.
A medical professional must evaluate the cardiac patient for any potential cardiac problems like coronary artery diseases, which must be treated immediately. Therefore, the activation of emergency services comes before anything else.
Post-Cardiac Arrest Care
Cardiac arrest survivors often face physical, cognitive, and psychological challenges after they're discharged from the hospital. They may require ongoing therapies and interventions. Therefore, aftercare is still a crucial component of the chain of survival to ensure a lasting recovery.
Referral to appropriate counseling or other support services, including primary care, should be assessed. Health professionals may also find some circumstances distressing, and their employing organizations should have proper support systems when required.
According to the American Heart Association for Emergency Cardiovascular Care, accurate neurological prognostication in brain-injured cardiac arrest survivors is critical. This ensures that patient with significant potential for recovery is not destined for certain poor outcomes due to care withdrawal. This added step asks care teams to plan to investigate both the causes and the secondary effects of the out-of-hospital cardiac arrest event and ensure treatment continues.
The American Heart Association is committed to supporting research to update both in and out-of-hospital rescue guidelines. This means that the chain will likely improve in the next few years. The current basic life support guidelines still provide a strong outline for thinking about care and remind us that having knowledgeable certified rescuers is supremely important.
What's the role of a bystander in the Chain?
The first three steps of the Chain must often be performed by bystanders, whether they know the cardiac arrest patient. Therefore, it's vital to that you recognize when cardiac arrest occurs and activate the Emergency Medical Services by calling 911.
But performing Cardiopulmonary Resuscitation and public access defibrillation as soon as possible is key to improving outcomes. According to 2014 statistics, about 45% of out-of-hospital cardiac arrest survivors received CPR from bystanders.
Why did the American Heart Association's Chain of Survival change?
The American Heart Association reports that sudden cardiac arrest survival improved around 2012. However, there haven't been substantive survival increases since. Recently, the American Heart Association determined that aftercare received after hospital discharge was missing in surviving sudden cardiac arrest. As a result, recovery in the Chain of Survival was added to the adult and pediatric in-hospital and out-of-hospital chains of survival. Additionally, almost 500 other recommendations were made to increase the cardiac arrest survival rates.
There is no earlier method to reliably identify patients in whom a poor neurological outcome is inevitable, so the American Heart Association's current guidelines for adults also recommend against the withdrawal of life support for at least 72 hours after resuscitation and rewarming from any induced hypothermia.
These changes accompany other notable researched-based changes. For example, the ABC/CAB swap several years ago. Until 2015, the American Heart Association and other health organizations reviewed and updated guidance for CPR every five years.
Successful resuscitation requires quick and coordinated action by trained rescuers, each performing an important role. The chain of survival is an internationally recognized approach to resuscitation and summarizes the essential interventions to improve patient outcomes during medical emergencies. The chain of survival applies to all OHCAs in adults, children, and infants. Early recognition of OHCA, immediate CPR, and early defibrillation remain the key to improving outcomes. The evidence for high-quality post-resuscitation care continues to evolve to improve results further.