Chest compressions most important of CPR Cardiopulmonary resuscitation，or CPR，can save the life of someone whose heart has stopped．The condition is called cardiac arrest．The heart stops pumping blood．The person stops breathing．Without lifesaving measures，the brain starts to die within four to six minutes． CPR combines breathing into the Victim’s mouth and repeated presses 0n the chest．_____（1） However，a new Japanese study questions the usefulness of mouth—to—mouth breathing．The study was published in the British medical magazine，The Lancet3．Doctors in Tokyo led the research．It examined more than four thousand people who had suffered cardiac arrest. In all the cases．witnesses saw the event happen． More than one thousand of the victims received some kind of medical assistance from witnesses．Seven hundred and twelve received CPR． Four hundred and thirty—nine received chest presses only．____（2）The researchers say any kind of CPR improved chances of the patient’s survival．But，I they said those people treated with only chest presses suffered less brain damage．Twenty—two percent survived with good brain ability．_____（3） The American Heart Assocication changed its guidelines for CPR chest presses in 2005．______（4）Gordon Ewy is a heart doctor at the University of Arizona College of Medicine in Tucson．He wrote a report that appeared with the study．Doctor Ewy thinks the CPR guidelines should be changed again．He said the heart association should remove rescue breaths from the guidelines．He argues that more witnesses to cardiac arrests would provide treatment if rescue breaths are not a part of CPR．Hesays this would save lives．_______（5） Cardiac arrest kills more than 300，000 people in the United States every year．The American He，art Association says about ninety—five percent 0f victims die before they get to a medical center．