The “Chain of Survival” is a sequence of time-sensitive actions that, when linked together, maximize the chance of survival and recovery for a person experiencing sudden cardiac arrest (SCA). Its effectiveness relies on the rapid, seamless transition from one step to the next, beginning the moment a person collapses. The model emphasizes that the outcome depends on every step being executed quickly and correctly. The specific links are tailored for different environments, such as out-of-hospital versus in-hospital, to address unique challenges.
The Critical First Links
The out-of-hospital chain focuses heavily on the initial three links, involving the immediate response of bystanders. The first link is the prompt recognition of cardiac arrest and the activation of the emergency response system. Immediate action is paramount because the chance of survival decreases by 7 to 10 percent with every minute that passes without intervention.
The second link requires immediate, high-quality Cardiopulmonary Resuscitation (CPR), emphasizing chest compressions. High-quality CPR ensures a rate between 100 and 120 compressions per minute and a depth of at least two inches for adults, allowing the chest wall to fully recoil. This action circulates oxygenated blood to the brain and heart, sustaining the organs until definitive treatment. CPR alone cannot restart a heart in ventricular fibrillation (VF), the most common initial rhythm in sudden cardiac arrest.
The third link for a shockable rhythm like VF is rapid defibrillation using an Automated External Defibrillator (AED). Defibrillation delivers an electrical shock to interrupt the chaotic electrical activity, allowing the heart’s natural pacemaker to re-establish a normal rhythm. This step is time-sensitive, as the window for successful defibrillation rapidly diminishes, making immediate access to an AED a life-saving measure.
Professional and Hospital Care
The later links transition care from the bystander to trained medical personnel, starting with advanced resuscitation. The fourth link, Advanced Life Support (ALS), is provided by emergency medical services (EMS) and involves interventions beyond basic CPR and defibrillation. These procedures include administering medications (such as epinephrine and antiarrhythmics), securing an advanced airway, and making transport decisions.
The fifth link is integrated post-cardiac arrest care, beginning upon the patient’s arrival at a specialized hospital facility. This phase manages post-cardiac arrest syndrome, which affects multiple organ systems. Key interventions include Targeted Temperature Management (TTM) to minimize brain injury in comatose survivors, controlling the core body temperature between 32°C and 36°C. This care also involves hemodynamic monitoring to maintain optimal blood pressure and organ perfusion. The final link of the chain, recovery, focuses on long-term neurological, physical, and emotional support for the survivor.
The Concept of the Pediatric Chain
The Pediatric Chain of Survival differs from the adult model because pediatric cardiac arrest usually results from progressive respiratory failure or shock, meaning a lack of oxygen is the initial trigger. Unlike adults, who often experience a primary cardiac event, children require a different approach.
The first link in the pediatric sequence is Prevention, which is not a formal link in the adult out-of-hospital chain. This focus addresses common causes of oxygen deprivation in children, such as accidental trauma, drowning, and respiratory illnesses. Since oxygen loss is the primary issue, immediate rescue breathing and ventilation are often prioritized.
The next links involve early, high-quality CPR and the rapid activation of the emergency response system. For a lone rescuer, the sequence often dictates initiating two minutes of CPR first before calling for help, especially if the arrest was unwitnessed. The final links—early advanced resuscitation and integrated post-cardiac arrest care—mirror the adult chain but utilize specialized equipment and drug dosages tailored for the pediatric patient.