The Scandinavian AED and Mobile Bystander Activation Trial (SAMBA)

Sudden cardiac death is a major health problem in the western world. In Europe alone nearly 300 000 patients are affected annually. The majority of victims suffering from an Out-of-Hospital Cardiac Arrest (OHCA have an initial cardiac rhythm that can be treated by means of defibrillation. In most emergency medical systems (EMS) time to defibrillation is too long and survival averages 10 %.However, when laymen operated Automated External Defibrillators (AEDs) are used within the first minutes, 7 out of 10 may survive. The aim of "The Scandinavian AED and Mobile Bystander Activation" (SAMBA) trial is to evaluate if a Mobile Phone Positioning system and a smartphone application will increase the proportions of patients with an attached Automated External Defibrillator (AED) before arrival of the Emergence Medical System (EMS). Mobile phone technology and a smartphone application will be used identify and recruit nearby CPR-trained lay people and automated external defibrillators (AEDs) to patients suffering out-of-hospital cardiac arrest (OHCA). The system is currently running in Stockholm Sweden and in the Gothenburg region.

Early defibrillation in out-of-hospital cardiac arrest is associated with high survival rates. If the operator at the dispatch center suspects an out-of-hospital cardiac arrest he or she will activate the mobile positioning system (MPS) wich is integrated in the operators computer environment. After activation, the system will locate all CPR-trained volunteers nearby the suspected OHCA. By computer based 1:1 randomization lay volunteers will be alerted and dispatched in 50 % of all suspected OHCAs in where the system is triggered by the dispatchers. In the intervention group, the activation of the system is supposed to result in lay volunteers to be alerted and directed to fetch the nearest AED and commence early defibrillation. Dependent on geographical and logistical circumstances, at a minimum one lay volunteer or more will be alerted to provide bystander CPR only. In the control group the MPS will be activated and lay responders will be dispatched to suspected OHCA to perform CPR only. In both groups the ordinary EMS services are dispatched in a regular fashion.

In the intervention group mobile lifesavers will be directed to fetch the nearest AED and then attach it to the victim of OHCA. At least 1 volunteer will be directed to start CPR only

All adverse events reported at a prehospital stage will be collected and presented as minor or major events related to lay persons participating as mobile phone dispatched rescuers events related to patients. Minor events are negative safety events with the potential to harm the lay rescuer or patient such as technical malfunction or dispatcher related communication failure. Major events are negative events that actually harms the lay rescuer or OHCA patient due to system malfunction, such as unsafe scene or violation of integrity.

Additional (total) effect of mobile phone dispatched lay volunteers in both study groups (observational)

Proportion of AED attachment prior to the EMS by mobile phone dispatched lay volunteers. Both study groups combined.

Additional (total) effect of mobile phone dispatched lay volunteers in both study groups (observational)

Inclusion Criteria: All EMS-treated OHCAs within the Stockholm County, Copenhagen and VGR area and in whom the mobile positioning system is activated at the emergency dispatch center Exclusion Criteria: Crew witnessed OHCAs Patients <8 years of age OHCAs due to trauma, intoxication, or suicide OHCAs not treated by the EMS due to ethical reasons or obvious signs of death. No OHCA cases