• Public health

This year is the 50th anniversary of the introduction of modern resuscitation from cardiac arrest, made possible by the combination of closed chest compressions with external defibrillation and effective artificial ventilation.1 Inevitably this was restricted initially to hospitals, but within a few years the need to counter sudden death in the community led to the development of cardiac ambulances. The appreciation that lethal cardiac arrhythmias are not only due to acute myocardial infarction but can also occur unpredictably from a myriad of causes led to more complex responses. In most developed countries we now have public education on the need for rapid access to help, widespread training in cardiopulmonary resuscitation (CPR), means of early defibrillation where relevant and skilled aftercare—the so-called ‘chain of survival’.2 But daunting problems markedly limit success, irrespective of knowledge and training within the community. Even when death strikes suddenly and prematurely, many cases are complicated by severe underlying pathology that is not always amenable to prompt treatment. Even more importantly, only a very few minutes are available for effective resuscitation before apparently irreversible cerebral and cardiac changes make recovery impossible. Survival from out-of-hospital cardiac arrest (OOHCA) is therefore achieved only in a small minority, even of those ‘too young to die’. Investigating the predictors of success can help to prioritise efforts to improve results that are currently so dire. They have also been used as a guide for recognising futility, with the aim of curtailing resuscitation attempts that may have no chance of success.

Many studies have been published on the predictors of …