CPR is as easy as C-A-B

CPR is as easy as C-A-B
CPR is as easy as C-A-B

Change from “A-B-C” to “C-A-B.” A major change in basic life support is a step away from the traditional approach of airway-breathing-chest compressions (taught with the mnemonic “A-B-C”) to first establishing good chest compressions (“C-A-B”). There are several reasons for this change.

  • Most survivors of adult cardiac arrest have an initial rhythm of ventricular fibrillation (VF) or pulseless ventricular tachycardia (VT), and these patients are best treated initially with chest compressions and early defibrillation rather than airway management.

  • Airway management, whether mouth-to-mouth breathing, bagging, or endotracheal intubation, often results in a delay of initiation of good chest compressions. Airway management is no longer recommended until after the first cycle of chest compressions — 30 compressions in 18 seconds. The 30 compressions are now recommended to precede the 2 ventilations, which previous guidelines had recommended at the start of resuscitation.

  • Only a minority of cardiac arrest victims receive bystander CPR. It is believed that a significant obstacle to bystanders performing CPR is their fear of doing mouth-to-mouth breathing. By changing the initial focus of resuscitation to chest compressions rather than airway maneuvers, it is thought that more patients will receive important bystander intervention, even if it is limited to chest compressions.

Basic life support. The traditional recommendation of “look, listen, and feel” has been removed from the basic life support algorithm because the steps tended to be time-consuming and were not consistently useful. Other recommendations:

  • Hands-only CPR (compressions only — no ventilations) is recommended for the untrained lay rescuers to obviate their fears of mouth-to-mouth ventilations and to prevent delays/interruptions in compressions.

  • Pulse checks by lay rescuers should not be attempted because of the frequency of false-positive findings. Instead, it is recommended that lay rescuers should just assume that an adult who suddenly collapses, is unresponsive and not breathing normally (eg, gasping) has had a cardiac arrest, activate the emergency response system, and begin compressions.

  • Pulse checks by healthcare providers have been de-emphasized in importance. These pulse checks are often inaccurate and produce prolonged interruptions in compressions. If pulse checks are performed, healthcare providers should take no longer than 10 seconds to determine if pulses are present. If no pulse is found within 10 seconds, compressions should resume immediately.

  • The use of end-tidal CO2 (ETCO2) monitoring is a valuable adjunct for healthcare professionals. When patients have no spontaneous circulation, the ETCO2 is generally ≤ 10 mm Hg. However, when spontaneous circulation returns, ETCO2 levels are expected to abruptly increase to at least 35-40 mm Hg. By monitoring these levels, interruptions in compressions for pulse checks become unnecessary.

CPR devices. Several devices have been studied in recent years, including the impedance threshold device and load-distributing band CPR. No improvements in survival to hospital discharge or neurologic outcomes have been proven with any of these devices when compared with standard, conventional CPR.

Electrical therapies

  • Patients with VF or pulseless VT should receive chest compressions until a defi