[European Resuscitation Council guidelines for resuscitation 2010].

All rescuers trained or not, should provide chest compressions to victims of cardiac arrest. The aim should be to push to a depth of at least 5 cm at a rate of at least 100 compressions per minute, to allow full chest recoil, and to minimise interruptions in chest compressions. Trained rescuers should also provide ventilations with a compression-ventilation ratio of 30:2.

[European Resuscitation Council guidelines for cardiopulmonary resuscitation in 2005].

ADULT BASIC LIFE SUPPORT: The ratio of compressions to ventilations is 30:2 for all adult victims of cardiac arrest. AUTOMATED EXTERNAL DEFIBRILLATION: A single defibrillatory shock is delivered, immediately followed by two minutes of uninterrupted CPR. ADULT ADVANCED LIFE SUPPORT: In out-of-hospital cardiac arrest attended, but unwitnessed, by healthcare professionals equipped with manual defibrillators, give CPR for 2 minutes before defibrillation.