According to the AHA, chest compressions should be started immediately on anyone who is unresponsive and is not breathing normally. Oxygen will be present in the lungs and bloodstream within the first few minutes, so initiating chest compressions first will facilitate distribution of that oxygen into the brain and heart sooner. Previously, starting with "A" (airway) rather than "C" (compressions) caused significant delays of approximately 30 seconds.
"For more than 40 years, CPR training has emphasized the ABCs of CPR, which instructed people to open a victim's airway by tilting their head back, pinching the nose and breathing into the victim's mouth, and only then giving chest compressions," noted Michael R. Sayre, MD, coauthor and chairman of the AHA's Emergency Cardiovascular Care Committee, in an AHA written release. "This approach was causing significant delays in starting chest compressions, which are essential for keeping oxygen-rich blood circulating through the body," he added.
The new guidelines also recommend that during CPR, rescuers increase the speed of chest compressions to a rate of at least 100 times a minute. In addition, compressions should be made more deeply into the chest, to a depth of at least 2 inches in adults and children and 1.5 inches in infants.
Persons performing CPR should also avoid leaning on the chest so that it can return to its starting position, and compression should be continued as long as possible without the use of excessive ventilation.
9-1-1 centers are now directed to deliver instructions assertively so that chest compressions can be started when cardiac arrest is suspected.
The new guidelines also recommend more strongly that dispatchers instruct untrained lay rescuers to provide Hands-Only CPR (chest compression only) for adults who are unresponsive, with no breathing or no normal breathing.
REFERENCE
Emma, H. (2010). 2010 AHA