Unexpected cardiac arrest remains a major problem worldwide; in Europe 375,000 people have sudden cardiac arrest yearly. It accounts for nearly 15% of all deaths in industrial countries.
The incidence of cardiac events increases with age and is more common in men. Nearly 90% of cases are related to ischemia when blood flow to the heart is impaired.
Other less frequent cardiac causes are cardiac rhythm disturbances, and congestive heart failure. Moreover, there are non-cardiac causes of cardiac arrest such as traumatism, major bleeding, intoxication, drowning…
Risk factors are similar of those related to coronary artery disease including smoking, obesity, sedentary lifestyle, diabetes and family history.
Witnessed cardiac arrest and the duration of the ‘no flow period’ (duration without any cerebral perfusion), the presence of a shockable rhythm (ventricular fibrillation) as initial arrhythmia and bystander cardiopulmonary resuscitation are major predictors of immediate survival described in the literature.
Reducing the no flow period is crucial and has a direct impact on survival; it can double or triple the survival rate.
Reducing the no flow period is crucial and has a direct impact on survival; it can double or triple the survival rate. Unfortunately in most countries only 20% of patients benefit from bystander cardiopulmonary resuscitation (CPR).
In a recent Scandinavian trial (The TTM study), they observed the efficacy of the national policy to learn CPR to the population and described a 73% of bystander CPR. This high percentage of resuscitation by witnesses was associated to 50% of survival, one of the highest described for out of hospital cardiac arrest.
Developments in the field
The chain of survival was recently prolonged with the adjunction of post cardiac arrest care especially the temperature management and percutaneous coronary intervention to restore coronary circulation.
The benefit of a strict management of temperature was well demonstrated in terms of neurological outcome but the best temperature target is always a matter of debate in the medical community.
Another recent development is the use of extracorporeal support during CPR. This specific intervention resulting in a short-term replacement of the heart to perfuse the organs, especially the brain, was actually reserved to hospitals with a high level of expertise, but remains an interesting development.
One of the main challenges in the future is probably the improvement of the early management of the cardiac arrest patient. Increasing the bystander CPR rate is the crucial first step of the management.
The result of all the advanced support from the advanced life support to the extracorporeal support depends on this very short period which changes ‘no flow’ to ‘low flow’ and changes fundamentally the neurologic prognosis of the patient.
You can read more from research published in Critical Care.