This is the VOA Special English Health Report. 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 on the chest. CPR keeps blood and oxygen flowing to the heart and brain. However, a new Japanese study questions the usefulness of mouth-to-mouth breathing. The study was published in the British medical magazine, The Lancet. 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.