"which describes the blood flow from chest compressions compared to normal cardiac output"

Chest compression can save the lives of patient in cardiac arrest as it generate a small but critical amount of blood flow to the heart and brain. It provides oxygen quickly to the brain, heart, lungs and other organs until normal function of the heart and lung restored. When the patient is unresponsive without definite pulse or normal breathing then the responder should assume that the patient is in cardiac arrest. CPR or chest compression is used to keep oxygen circulating around the body until a defibrillator can be used or until the ambulance arrives. Moreover, defibrillator is a device used to help blood flow in order to help the patient survive or recover from cardiac arrest. This procedure can momentarily stops the heart and the chaotic rhythm and often allows the normal heart rhythm to resume. However, chest compression be given when the patient has no pulse while CPR is performed when the patient is unresponsive, not breathing and has no pulse.

your answer is "the 1950's"