Cardiac arrests often occur out of hospital, and as such, the need for early intervention is paramount. Chance of survival can reduce by up to 10% for every minute without CPR and defibrillation. Numerous studies have identified factors vital in a cardiac arrest sufferer’s prognosis, collated as the ‘Chain of Survival’; a four step process with input both before and during EMS care.
Note that the ‘chain’ proceeds past these steps to the transition of care from EMS environment to hospital, but this article will focus on the first four defined steps.
1. Early Recognition
Should someone suffer a cardiac arrest, their first critical influence in their chances of survival is that it is recognised. Ideally, a bystander is present and witnesses the episode, dialling 911 immediately, or even more ideal is that a bystander recognises or is alerted to (such as by the patient) an event which could lead to cardiac arrest (eg. chest pain) and dials 911 earlier.
2. Early CPR
The first minutes – even mere seconds – of a cardiac arrest are critical. CPR should be commenced without delay unless there is valid reason not to such as dangers present. Vital organ perfusion is lost rapidly without adequate circulation and rapidly leads to cellular damage and death. Immediate, effective CPR attempts to provide the heart and blood with adequate pressure to still perfuse the body, and even bring the heart back to an adequate self-functioning state.
3. Early Defibrillation
Though localities around the country, and world, differ in their defibrillation protocols, mounting evidence demonstrates that defibrillation is often most effective when performed early in a cardiac arrest provided the patient is in a shockable rhythm. Defibrillation disrupts abnormal cardiac electrical activity with a large electric shock that may effectively ‘kick-start’ the heart back into normal electrical activity. Typically, earlier defibrillation times correlate with more shockable electrical activity still occurring in the heart. Defibrillation can also occur prior to an EMS unit’s arrival as some public and private locations have automatic external defibrillators on-hand which, when applied to a patient’s body, can advise the bystander/s if a shock should be delivered.
4. Early Advanced Care
Coming back to the first link; ‘Early Recognition’, ideally EMS services have been activated early and reach the scene in a viable timeframe. Though a defibrillator may not have already been utilised, the EMS unit will have one. Additionally, advanced procedures such as advanced airway management, intravenous access, drug administration (such as epinephrine and anti-arrhythmics including amiodarone) and other procedures such as thoracentesis (in the setting of a tension pneumothorax) may be performed. Furthermore, an EMS unit will be able to transport the patient to hospital; their destination should the cardiac arrest be viable, and sometimes location of definitive intervention such as surgery.
These four steps in the Chain of Survival are all crucial components of your care as an EMS provider. The earlier these steps are performed effectively, the higher the chances of survival and possibly even the patient being able to walk out of hospital.