FIFTEEN IS NO LONGER the magic number when it comes to performing cardiopulmonary resuscitation (CPR) on adults, according to the American Heart Association (AHA), which released the 2005 AHA Guidelines for CPR and Emergency Cardiovascular Care in late November. To achieve the best compression rate and decrease the frequency of compression interruptions, the AHA's new guidelines instruct practitioners to adopt a universal compression-ventilation ratio of 30:2 for all one-rescuer or two-rescuer CPR for adults. Experts believe this new ratio will simplify one- or two-rescuer CPR training for adults, in addition to lay rescuer resuscitation. Practitioners should use the 15:2 compression-ventilation ratio for two-rescuer CPR used for infants and pre-pubescent children.

With sudden cardiac arrest (SCA) killing approximately 250,000 people outside of the hospital each year, the AHA saw fit to refine the guidelines through the most comprehensive investigation of CPR practices to date. Researchers found that in some cases, those administering CPR didn't deliver the correct number or depth of chest compressions, administered too much ventilation (usually to intubated victims), and frequently interrupted compressions. This reduced cardiac output, coronary and cerebral blood flow, and the prospect for successful resuscitation. Consequently, the authors of the guideline changed the recommendation from a compression-ventilation ratio of 15:2 to 30:2 for adults until an advanced airway is in place, and 15:2 for two-rescuer CPR administered to infants or children.

CPR or AED?

According to the AHA, the survival rate of 6% or less for those who experience out-of-hospital cardiac arrest causes a difficulty in creating clinical trials that can demonstrate long-term outcomes. When a victim experiences ventricular fibrillation (VF) SCA, should practitioners administer CPR first, or should they use an automatic external defibrillator (AED)? According to the new guideline, for some patients, pump first and shock later. EMS rescuers may perform CPR for about 2 minutes before using the AED for treating out-of-hospital VF or pulseless ventricular tachycardia (VT), when EMS responders didn't personally witness the arrest or when the call-to-arrival time is greater than 4 to 5 minutes.

New for 2006 is a recommendation for rescuers to resume CPR (starting with chest compressions) right after delivering a single shock. Rescuers should perform uninterrupted compressions (without stopping to check circulation) until about 2 minutes of CPR is complete. This new one-shock strategy brings with it the challenge of defining the optimal amount of energy needed for that first shock in adults. Experts state that an initial shock of 150 to 200 joules is appropriate with a biphasic truncated exponential waveform, and a 120 joules initial shock is approved with a rectilinear biphasic waveform. For EMS responders and other providers still using monophasic defibrillators, experts recommend a 360 joules shock for the initial and subsequent shocks. Those responding to child victims should take care to use an initial dose of 2 joules/kg, and 2 to 4 joules/kg for subsequent monophasic or biphasic shocks.

After the shock

The guideline's researchers found no evidence that routine administration of antiarrhythmic drugs at the time of cardiac arrest improved chances of survival. Consequently, the new guidelines instruct rescuers to resume CPR (beginning with compressions) immediately after a shock, without stopping to check rhythms. Practitioners can administer antiarrhythmias or vasopressors during CPR or right after a rhythm check. Rescuers shouldn't stop chest compressions to check rhythm after administering a shock until they've performed about 2 minutes of CPR.

The bottom line of the 2005 AHA Guidelines for CPR and ECC: Push fast and hard, minimize chest compression interruptions, allow full-chest recoil, and defibrillate promptly when it's appropriate.

Source: Reprinted from For new CPR guidelines, think 30, Nursing2006 Critical Care, NT Taylor, January 2006.

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