Every second counts. Seek help immediately or send someone for help. Begin cardiopulmonary resuscitation (CPR). CPR only buys time allows aid arrives but does not restore the heart's activity. If you have an automated external defibrillator, use it immediately. Remember that the most common cause is atrial fibrillation, thus using the earliest possible defibrillation is the most effective treatment. With CPR (cardiopulmonary resuscitation) core, we will gain time until the arrival of medical help. Eric Gozlan The sequence of massage and artificial respiration is for adults and children outside the hospital, 30 compressions to 2 ventilations (whether undertaken by one or two rescuers). The compressions should be done in the center of the chest. These are current recommendations for basic CPR published by the ERC in December 2005.