The Use of Mobile Phones in Out of Hospital Cardiac Arrest to Increase Bystander CPR

Survival from out-of-hospital cardiac arrest (OHCA) is generally low, about 5-10%, with the exception of a few controlled settings (casinos, airports and some cities). The poor prognosis of OHCA is mainly explained by long time intervals between cardiac arrest, cardiopulmonary resuscitation (CPR) and defibrillation. To increase bystander actions and to decrease time to defibrillation substantial resources have been put into CPR educational campaigns and in recent years into the spread of automated external defibrillators (AEDs) in public venues. Still, the vast majority of the public with CPR training will never use their skills in real life. Mobile phone technology offers the possibility to locate single mobile phone users at any given moment. If designated lay responders immediately can be identified and recruited to the scene of nearby suspected OHCAs bystander CPR, CPR quality and finally survival might be increased.

Mobile phone positioning and dispatching of lay responders:

Tailored mobile phone services that use MPS to locate selected mobile phone users can be developed for different purposes. A computer-based application for mobile phone positioning and dispatch of lay responders is developed for the purpose of this study and is referred to as the Mobile Lifesaver Service (MLS). All participants connected to the MLS are called Mobile Responders (MRs). The MLS acts as an interface between the emergency medical service (EMS) data system and the MPS. The MLS handles the localisation and dispatching of MRs based on the data present in the EMS data system. The location of all incoming calls to all dispatch centres in Sweden is determined automatically.

When the dispatcher receives an emergency call from a witness of a suspected OHCA the dispatcher activates the MLS in parallel with standard EMS. When the MLS is activated it uses the MPS to compare the current geographical position of all MRs connected to the MLS with the position of the incoming emergency call of the suspected cardiac arrest. If one or more MRs is present within a radius of 500 m (optional) from the suspected arrest the MRs receives a cardiac arrest alert with a computer generated phone call and a text message (i.e. SMS = short message system) with information about the place of the suspected cardiac arrest. A map for finding the way to the suspected OHCA is also sent. Additional information can, if needed, be sent to the MRs.

For further details see "Mobile phone technology identifies and recruits trained citizens to perform CPR on out-of-hospital cardiac arrest victims prior to ambulance arrival." Ringh M, Fredman D, Nordberg P, Stark T, Hollenberg J. Resuscitation. 2011 Dec;82(12):1514-8.

Data from earlier non randomized pilot studies in urban Stockholm has shown that CPR was performed by MLS dispatched lifesavers prior to ambulance, firefighters and police in about 20 % of all cases of true OHCAs.

The hypothesis is that bystander CPR in Stockholm County can be increased from 50 % to 62,5% if the MLS is used. An estimated number of 6000 MR needed is based on earlier pilot studies.

The current proportion of bystander CPR is derived from OHCA registry data but is uncertain.

A safety and efficacy analyze will be made at approximately 200 true OHCA cases.

A ethical and safety board and log for adverse events will be set up.

Inclusion criteria

• All suspected OHCAs in Stockholm County
• All EMS treated out of hospital cardiac arrest in Stockholm County were the mobile positioning system is triggered

Exclusion criteria

• Traumatic OHCA
• Children under 8 years of age
• Suicide
• Intoxications
• Obvious signs of death
• Do not resuscitate orders (DNR)