The Evolution of Cardiopulmonary resuscitation: Unraveling the Shift from A-B-C to C-A-B

For seasoned CPR practitioners, the perplexing shift from A-B-C to C-A-B might have raised questions about the rationale behind this rearrangement. What prompted the change in the sequence of cardiopulmonary resuscitation steps, prioritizing chest compressions before airway and breathing?

Back in 2010, the American Heart Association (AHA) released new guidelines for CPR, altering the conventional order of steps. Previously, A-B-C was the norm, advocating airway and breathing as the initial actions, followed by chest compressions. The paradigm shift introduced C-A-B, emphasizing chest compressions as the primary step, followed by airway and breathing.

The Vital Significance of Blood Flow

Comparable to how one can hold their breath for a brief period without experiencing brain damage, individuals in cardiac arrest can endure a momentary lack of breath without severe consequences. The critical requirement is to restore blood circulation promptly.

Any disruption in blood flow significantly reduces the chances of survival. Prioritizing rescue breathing often led to delays in initiating chest compressions. Even if giving breaths first held substantial importance (which it does not), the resultant delays were never intended.

Eliminating Time Lags of cardiopulmonary resuscitation

Rescuers often faced concerns while trying to open the airway and form an effective seal. Factors like the discomfort factor and the hassle of retrieving a CPR mask from a purse or briefcase added to the delay. All this extra time hindered the essential task at hand: performing chest compressions.

The AHA clarified this alteration in the following manner:

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

With chest compressions as the first step, patients only have to hold their breath for an additional 18 seconds while blood circulation is reinstated. It's a worthy trade-off.

Promoting blood circulation, even when the blood might have limited oxygen content, stands as the most crucial function of CPR. The 2010 AHA Guidelines for CPR truly elevated chest compressions to the forefront.

The Essentials of Chest Compressions For adult patients, chest compressions should reach a depth of at least two inches and be administered at a rate between 100-120 per minute.

Delivering chest compressions too slowly fails to generate adequate blood pressure to reach the brain efficiently. On the other hand, compressions that are too rapid risk insufficient blood return to the chest before the next cycle.

Ever since the 2010 AHA Guidelines for CPR were released, scientific evidence has consistently supported chest compressions as a substitute for rescue breathing. Hands-only CPR, once considered a last resort for untrained rescuers, has now become the standard of care.

Even some professional rescuers have opted to exclude rescue breathing from CPR. When artificial breathing is provided, advanced procedures are less favored, with a preference for simpler ventilation techniques.

NCLEX: National Council Licensure Examination, OIIQ: Ordre des infirmières et infirmiers du Québec, OIIAQ: Ordre des infirmières et infirmiers auxiliaires du Québec