The most important update in the 2010 edition of the International Guidelines for Cardiopulmonary Resuscitation is to change the order of ABC to CBA, with A for open airway, B for artificial respiration, and C for chest cardiac compressions. Most prehospital respiratory cardiac arrests are cardiogenic respiratory cardiac arrests with adequate oxygen in the body, and even some patients with respiratory cardiac arrests may experience large gasping behaviors before the respiratory cardiac arrest, providing some oxygen, so the order of CPR was changed to CBA.