The goal of cardiopulmonary resuscitation on people with cardiac arrest is to keep them alive--without brain damage. A Japanese study of more than 4000 incidents shows that those who received chest compressions alone did twice as well as those who received both chest compressions and mouth-to-mouth resuscitations. Traditional CPR requires both chest compressions and mouth-to-mouth resuscitation. Lots of bystanders don't perform mouth-to-mouth, for fear of contracting disease or doing it wrong. Dr. Gordon Ewy is Chief Cardiologist at the University of Arizona Medical School.