Chain of Survival
 
In 1990, the American Heart Association developed the Chain of Survival. This protocol addresses the fact that most SCA episodes occur outside of a hospital, with death occurring within minutes of onset. For the Chain to be effective, quick execution of each and every link is critical. With each minute that passes, the likelihood of survival decreases 7-10%.
 

Time After the
Onset of Attack
Survival Chances
With every minute
Chances are reduced by 7-10%
Within 4-6 minutes
Brain damage and permanent death start to occur
After 10 minutes
Few attempts at resuscitation succeed

 

To provide the best opportunity for survival, each of these four links must be put into motion within the first few minutes of SCA onset:

  • Early Access to Emergency Care must be provided by calling 911.
  • Early CPR should be started and maintained until emergency medical services (EMS) arrive.
  • Early Defibrillation is the only one that can re-start the heart function of a person with ventricular fibrillation (VF). If an automated external defibrillator (AED) is available, a trained operator should administer defibrillation as quickly as possible until EMS personnel arrive.
  • Early Advanced Care, the final link, can then be administered as needed by EMS personnel.
When each link in the chain works successfully, the chance of surviving SCA increases greatly.
 

Type of Care for SCA Victims after Collapse
Chance of Survival
No care after collapse
0%
No CPR and delayed defibrillation (after 10 minutes)
0-2%
CPR from a non-medical person (such as a bystander or family member) begun within 2 minutes, but delayed defibrillation
2-8%
CPR and defibrillation within 8 minutes
20%
CPR and defibrillation within 4 minutes; paramedic help within 8 minutes
43%

 

Since more than 70% of SCA cases occur at home, and another 10% to 15% occur at work 2 , trained EMS personnel are unlikely to be at the scene at onset. Therefore, trained lay responders with quick access to defibrillation units can be a vital asset when SCA strikes. In certain environments, where the Chain is strong and when defibrillation occurs within the first few minutes of cardiac arrest, survival rates can approach 80% to 100%. 3
 
People who survive sudden cardiac arrest have an excellent prognosis: 83% survive for at least one year, and 57% survive for five years or longer. In fact, when analyzed by age group, survival rates for SCA survivors are comparable to survival rates of people who have never had an event. Clearly, early intervention can offer years of productivity and fulfillment to victims of SCA.
 
 
Early Access
Chain of Survival

The first link in the Chain of Survival is the emergency care call.

When SCA strikes, an immediate 911 call is crucial; a delay of just a few minutes could prove fatal. By quickly recognizing a medical emergency, a bystander can help save a life.

Could you recognize the symptoms of SCA?

  • Unresponsiveness
  • Loss of consciousness
  • Lack of pulse
  • Cessation of breathing

    • SCA is not the same as a heart attack. However, a victim of either condition requires an immediate 911 call.

    Your Part in the 911 Call
    When fielding a 911 call, the emergency medical services (EMS) dispatcher may ask the caller questions such as these (provided by the American Heart Association):

  • "What is your emergency?"
    To answer this question, describe the situation as extensively as possible, with such replies as "A customer had sudden chest pain and has now collapsed." Or "They've lost consciousness and they don't seem to be breathing."

  • "What's happening now?"
    Respond: "My friend is giving CPR. We have an automated external defibrillator (AED)." Or, "We're trying to find a medically trained person to assist us."

  • "Where is the victim located?"
    Respond: "We are at the Evergreen Company, here at 1234 Fifth Avenue NE, in the back hall."

  • "What number are you calling from?"
    Respond: "The number is 978-555-1313."

    • The dispatcher may give directions such as "Stay on the line until I tell you to hang up. Rescuers are being sent to your location. Please meet them and direct them to the scene." Some dispatchers can provide medical care instructions, such as for CPR and the defibrillation process, over the phone.

    A prompt 911 call sets the Chain of Survival in motion, giving the next two links, CPR and early defibrillation, the greatest opportunity for success.

     
    Early CPR
     
    Chain of Survival
    Cardiopulmonary resuscitation (CPR) is the second link in the Chain of Survival; it is the link that can buy life-saving time between the first link (Early Access to Emergency Care) and the third link (Early Defibrillation).
    During SCA, the heart twitches irregularly most often due to ventricular fibrillation (VF) and cannot pump oxygenated blood efficiently to the brain, lungs, and other organs. The victim quickly stops breathing and loses consciousness.
    However, prompt CPR can help sustain life during VF. The mouth-to-mouth breathing and chest compressions help oxygenated blood flow to the person's brain and heart, until defibrillation can attempt to restore normal heart pumping.
     
    Your Part in the CPR Link

    Once an SCA victim collapses and a bystander calls 911, the next step in the Chain is to perform CPR if you are trained, or to find someone who is. Lay people initiate CPR in more than half of SCA cases in which someone has witnessed the incident. 4 It's important, therefore, to increase the number of trained CPR lay people and the number of training programs in your schools and community.
    Although CPR can sustain life for a short time, it must be followed within minutes by the third link, early defibrillation. Only when combined with early defibrillation and early advanced care can CPR significantly increase an SCA victim's chance for long-term survival.

     

     

    Early Defibrillation
    Chain of Survival
    Although it is an important link in the Chain of Survival, CPR alone cannot fully resuscitate a person in SCA. Early defibrillation is the third and perhaps most significant link. Most SCA victims are in ventricular fibrillation (VF), an electrical malfunction of the heart that causes the heart to twitch irregularly. Defibrillation, the delivery of an electrical shock to the heart muscle, can restore normal heart function if it occurs within minutes of SCA onset.
    When CPR and defibrillation are provided within eight minutes of an episode, a person's chance of survival increases to 20%. 1 When these steps are provided within four minutes and a paramedic arrives within eight minutes, the likelihood of survival increases to over 40%. 1
     
    Defibrillation, the Key to Survival
     
    According to the American Heart Association (AHA), in cities where defibrillation is provided within 5-7 minutes, the survival rate from SCA is as high as 49%. 1 The AHA also cites that after automated external defibrillators (AEDs) were placed at Chicago's O'Hare and Midway Airports, 9 out of 14 SCA victims (64%) were revived with an AED and had no permanent neurological damage.
    However, the availability of AEDs in locations such as airports, airplanes, offices, community centers, and other public places is an evolving trend. The process began almost forty years ago, when the time-sensitivity of SCA and the importance of pre-hospital care first captured the attention of Dr. J.Frank Pantridge.

     

     

    Early Advanced Care
    Chain of Survival

    The fourth link in the Chain of Survival is advanced care. Paramedics and other highly trained EMS personnel provide this care, which can include basic life support, defibrillation, administration of cardiac drugs, and the insertion of endotracheal breathing tubes. This type of advanced care can help the heart in VF respond to defibrillation and maintain a normal rhythm after successful defibrillation.

    The trained EMS personnel monitor the patient closely on the way to the hospital, where more definitive diagnostic evaluation can occur.