The American Heart Association rearranged the order of CPR steps from A-B-C which means Airway and Breathing first followed by Chest Compression to a new order, C–A–B.  So why did it change?

Humans can hold their breath a minute or two without having brain damage.  Those in cardiac arrest can go sometimes even longer than 2 minutes without taking a breath.  What is really needed is for their blood to get flowing again.  Delays in blood flow reduces chances of survival.

When rescuers are worried about opening the airway and making an adequate seal, searching for a mask or barrier—the delay can be significant. All that extra time was getting in the way of the real help from chest compression.

Here is what the American Heart Association had to say about the change:         

“By changing the sequence to C-A-B, chest compression will be initiated sooner and ventilation only minimally delayed until completion of the first cycle of chest compressions (30 compression should be accomplished in approximately 18 seconds).”

By starting chest compression first, the patient only has to hold his breath an extra 18 seconds while the blood gets flowing again. That’s a good trade. Moving blood along, even blood with arguably diminishing amounts of oxygen is the most important function of CPR.”

So it is understandable that chest compression come first followed by airway and breathing.  Any extra time getting in the way of real help, chest compressions, risks the patient’s life.