On Monday, October 18, the American Heart Association (AHA) released new guidelines for performing cardiopulmonary resuscitation, better known as CPR. The new guidelines call for rescuers to begin with hard, fast chest compressions, then open the airway and begin mouth-to-mouth breathing.
Up until now, CPR was taught using the mnemonic “ABC,” for “airway, breathing, circulation/compressions.” The new guidelines reverse the process, telling rescuers to proceed in the order “C-A-B” – that is, to start chest compressions immediately after calling 9-1-1, then address “airway” and “breathing. Once rescuers introduce mouth-to-mouth breathing into the sequence, they should perform 30 compressions then 2 breaths for all victims of sudden cardiac arrest (except newly born infants). These guidelines apply to both lay rescuers and health-care providers.
Chest compressions need to be of high quality, said the AHA, and rescuers should use the following techniques:
- Push fast: Compressions should be delivered at a rate of at least 100/min (previous guidelines said “approximately” 100/min)
- Push hard: The chest should be compressed at least 2 inches (5 cm) in adults and at least one third of the chest in infants and children (approximately 1.5 inches [4 cm] in infants and 2 inches [5 cm] in children).
- Let go: The chest should be allowed to recoil completely after each compression
- Keep pushing: Interruptions in chest compressions should be minimized
- Breathe lightly: Avoiding excessive ventilation
The new sequence is based on a growing body of evidence that suggests chest compressions are the most important factor in improving survival rates from cardiac arrest. In 2008, the AHA revised its guidelines for lay rescuers, saying that bystanders who did not want to perform mouth-to-mouth or who were not trained to do so could perform chest compressions only (abbreviated “CO-CPR”). CO-CPR might even be preferable, said Bentley Bobrow, MD, of the Arizona Department of Health Services in Phoenix. Bobrow led a team of researchers in a five-year observational study of more than 4,000 out-of-hospital cardiac arrest cases. Their results, published October 6 in the Journal of the American Medical Association, showed that people were 60 percent more likely to survive when bystanders used the simpler CO-CPR method and didn't stop to deliver rescue breaths.
While the new AHA guidelines stop short of CO-CPR, they are founded on the importance of continued, high-quality chest compressions. The new guidelines were developed because people are most likely to survive cardiac arrest when someone sees the person go into cardiac arrest and acts immediately. In most cases, electrical activity is still present in the heart immediately after cardiac arrest, although the pulse has stopped. These patients often can be successfully revived with chest compressions and delivery of an electric shock to the heart muscle, called defibrillation. However, in the old A-B-C sequence, chest compressions were delayed while airway and breathing were addressed. The change in the sequence to C-A-B, the AHA noted, means chest compressions will begin sooner, with only a small delay in beginning rescue breathing (ie, the time required to deliver the first cycle of 30 chest compressions, or approximately 18 seconds).
The AHA said they hoped the change would encourage bystanders to begin CPR, because they wouldn't have to begin with the most difficult steps – opening the airway and breathing. Sudden cardiac arrest occurs when the heart suddenly stops beating, often a heart attack, as a result of electrocution or near-drowning, or trauma. But overall, survival rates from out-of-hospital cardiac arrest are very low. Of the 300,000 people who experience out-of-hospital cardiac arrest each year in the United States, less than 8 percent survive. Survival rates from out-of-hospital cardiac arrest vary widely across the United States, from 3 to 15 percent.
The AHA also revised its “Adult Chain of Survival,” adding a fifth step to the previous sequence: of early recognition and activation of the emergency response system, early CPR, early AED, and early advanced care. The fifth step, “Post-Cardiac Arrest Care,” emphasizes the importance of skilled and integrated care after cardiac arrest.