National and reporting differences of pre-hospital factors in extracorporeal cardiopulmonary resuscitation studies

Extracorporeal cardiopulmonary resuscitation is the rapid deployment of extracorporeal life support during cardiac arrest and has emerged as a rescue therapy for refractory cardiac arrest. Systemic circulation and oxygenation are temporarily restored, such that medical efforts can be focussed on the diagnosis and treatment of the underlying cause of the arrest. Observational research has shown this may improve survival with good neurological outcome. Crucial in resuscitation is the interval between arrest and return of circulation. Four factors are of influence during this phase: 1) witnessed arrest, 2) no-flow duration, 3) bystander basic life support, and 4) low-flow duration. The purpose of this review is to describe the current level of evidence for these factors in conventional and extracorporeal cardiopulmonary resuscitation for out-of-hospital cardiac arrest. Underreporting and national variability of the pre-hospital links in the chain-of-survival is prevalent. Consistent reporting is essential for new trials to enable comparison and generalisation to other regions