The Paradigm Shift from CPR to CCR

Cardiocerebral resuscitation (CCR) is a new approach for resuscitation of patients with cardiac arrest. The CCR method has been shown to dramatically improve survival in the subset of patients most likely to survive: those with witnessed arrest and shockable rhythm on arrival of EMS. It is composed of 3 components: 1) continuous chest compressions for bystander resuscitation; 2) a new emergency medical services (EMS) algorithm; and 3) aggressive post-resuscitation care. The CCR method advocates continuous chest compressions without mouth-to-mouth ventilations for witnessed cardiac arrest. It advocates either prompt or delayed defibrillation, based on the 3-phase time-sensitive model of ventricular fibrillation (VF). For bystanders with access to automated external defibrillators and EMS personnel who arrive during the electrical phase (i.e., the first 4 or 5 min of VF arrest), the delivery of prompt defibrillator shock is recommended. However, EMS personnel most often arrive after the electrical phase—in the circulatory phase of VF arrest. During the circulatory phase of VF arrest, the fibrillating myocardium has used up much of its energy stores, and chest compressions that perfuse the heart are mandatory prior to and immediately after a defibrillator shock. Endotracheal intubation is delayed, excessive ventilations are avoided, and early-administration epinephrine is advocated.

As per WHO census statistics mortality due to cardiac causes has overtaken mortality due to all cancers put together. Sudden cardiac arrest remains a leading cause of death besides loss of years of productive life. Out of 100,000 Indians, approximately 4280 die of SCA.1

The current renaissance in resuscitation science have greatly expanded our understanding of cardiac arrest physiology and have been able to identify multiple potential therapeutic targets, promising improved clinical outcomes from cardiac arrest. However, the existing mechanisms of providing clinical guidance and training in this area are inadequate.

For the past several decades, a set of consensus guidelines have been generated every 5 years under the auspices of the International Liaison Committee on Resuscitation (ILCOR). Within a year, updates are made available to the advanced cardiac life support (ACLS)/basic life support (BLS) curriculum, a process overseen by the American Heart Association (AHA). These courses have served as a standard-of-care for both prehospital and in-patient providers, emphasizing uniformity of content and format to ensure, a predictable knowledge base and skills performance. The increasing velocity and refinement with regard to our understanding of cardiac arrest physiology and therapeutics, may warrant a different approach to training and clinical practice going forward, with the optimal strategy modified for the individual institution or emergency medical services (EMS) agency based on available resources and the patient population served.2 The latest guidelines were published in 2005, which was supplemented frequently. Gordon Ewy and Kern practised a different paradigm of Cardiopulmonary Resuscitation (CPR) called Cardiocerebral resuscitation (CCR) and their recommendations have been approved and added in the guidelines.3 Probably the components of Cardiocerebral resuscitation will be emphasized in the upcoming revised 2010 guidelines recommended in the 2010 ILCOR meet.

In spite the use of updated guideline, survival rates remain disappointingly low in emergency cardiac care that includes CPR. One contributor to poor survival is that CPR has heretofore been advocated for 2 distinctly different pathophysiologic conditions: primary cardiac arrest, in which the arterial blood is almost always fully oxygenated at the time of the cardiac arrest, and cardiac arrest secondary to respiratory failure, in which the initially normal cardiac output in spite of the lack of ventilation leads to severe hypoxemia, hypotension, and secondary cardiac arrest.4 Therefore, different approaches are no doubt necessary.

Cardiocerebral resuscitation (CCR) is a new approach to patients with out-of-hospital cardiac arrest that improves neurologically intact survival rates by 250%–300% over the approach advocated by the 2000 American Heart Association guidelines. Also the EMS systems realize these improvements, without adding a single new gadget or device. The concept of CCR was designed on better understanding of Physiology of VF associated three phase model of SCA and few studies done at different centers which differ from the current ACC-AHA guidelines. The observations of these studies conclude with some very interesting facts. One of the many important concepts to come forward since “Guidelines 2000” were published is the 3-phase, time dependent concept of cardiac arrest due to ventricular fibrillation articulated by Weisfelt and Becker.5
Components of CCR
CCR consists of three major components:

Continuous chest compressions (CCC) without mouth-to-mouth ventilation for all bystanders of witnessed cardiac arrests and for first responders.
A new advanced cardiac life support algorithm that delays endotracheal intubation, emphasizes minimal interruptions of chest compressions, deemphasizes positive-pressure ventilations, prioritizes defibrillation according to the three-phase time-sensitive model of ventricular fibrillation, and encourages early administration of epinephrine. Cardiocerebral resuscitation is also for basic EMTs—who should deliver continuous chest compressions at a rate of 100 per minute. Invasive airway insertion is delayed, and positive-pressure ventilations are not utilized during the initial minutes of resuscitation. Epinephrine, when appropriate, is administered via IV or IO ASAP when paramedics arrive.
The newest component of cardiocerebral resuscitation is advocating the establishment of cardiac arrest centers that can provide optimal care that includes urgent cardiac catheterization, controlled mild therapeutic hypothermia and standardized supportive care for patients in coma after resuscitation from cardiac arrest (Table 1).3,6

According to this model, optimal treatment of cardiac arrest is phase-specific and includes: i) the electrical phase, which extends from the time of cardiac arrest to approximately 4 minutes following the arrest; (ii) the circulatory phase, from approximately 4 to approximately 10 minutes after cardiac arrest; and (iii) the metabolic phase, extending beyond approximately 10 minutes after cardiac arrest. Importantly, in this model the term phase is designated for the maximally effective and most critical initial therapy for that period. However, the time boundaries between phases are approximate and not precisely defined in the current literature.5

Early defibrillation is ILCOR class I recommendation. A good example of early defibrillation is ICD within 15-20 sec and the conversion rate is far superior. Studies using automated external defibrillators (AEDs) to achieve rapid defibrillation (i.e., within 4 minutes of cardiac arrest) have demonstrated improved survival in a variety of settings and situations. The effectiveness of early defibrillation is well established and can result in survival rates of up to 50%, during electrical phase.5

The most important lifesaving therapy in this phase may be to first provide oxygen delivery (chest compression/ventilation under current guidelines), followed by defibrillation (i.e., delaying defibrillation by 1-3 minutes). According to a study, after 5 minutes of cardiac arrest, immediate defibrillation resulted in 30% successful defibrillation (3/10) and 0% return of spontaneous circulation (ROSC) (0/10), whereas 1 minute of CPR plus epinephrine before defibrillation resulted in 70% successful defibrillation (7/10) and 40% ROSC (4/10). Outcomes appear to be improved when defibrillation is briefly delayed in favor of providing some limited circulation of blood with partial restoration of substrates including oxygen, or washout of deleterious metabolic factors that have accumulated during ischemia. This change in therapy could affect a large number of cardiac arrest cases because only a minority of patients are currently attended by rescuers within 4 minutes of arrest (i.e., in the electrical phase), and far greater numbers of patients are treated during the circulatory phase.5

The effectiveness of both immediate defibrillation and CPR followed by defibrillation decreases rapidly and survival rates appear poor. During the metabolic phase (after approximately 10 minutes of arrest), tissue injury from global ischemic events and from reperfusion can result in circulating metabolic factors that cause additional injury beyond the effects of local or focal ischemia. However, the best cellular protection (decreasing cell death by 73%) occurred when cooling was performed prior to reperfusion, even if reperfusion with oxygenated media plus substrate was delayed for 10 minutes to allow time for cooling (i.e., cooling first, then reperfusion). A possible protective mechanism may involve hypothermia-mediated attenuation of the rapid oxidant burst observed with reperfusion. This challenges the current practice of immediate reperfusion for all ischemic conditions.5

It is not worthy, that AHA recently advocated "hands-only" or "compression-only" CPR for bystanders of witnessed arrests. These have been advocated since years. However, in our opinion the AHA recommendations go far enough, as they state that trained individuals should still utilize the 30:2 compression-to-ventilation ratio if ventilations with minimal interruptions of chest compressions can be performed.6,7
While ventilations are probably necessary in unwitnessed cardiac arrests, patients with witnessed arrests do not initially need assisted ventilation because their arterial oxygen content is sufficient for several minutes of chest compression-only CPR. In subjects who gasp, the arterial oxygen content remains adequate for up to 15 minutes with chest compressions only. Because the perfusion of the brain and heart are so marginal during resuscitation efforts, interrupting or delaying chest compressions for ventilation or other interventions, except for defibrillation, is deleterious.
If there is more than one person on scene, should one of the rescuers do assisted ventilations while the other does CCC? Surprisingly, the answer is no. With normal ventilation, breathing results in a negative pressure inside the chest that not only causes air to enter the lungs, but enhances blood return to the heart as well. This negative intrathoracic pressure also improves cerebral blood flow. On the other hand, when one ventilates a patient with cardiac arrest, one is increasing the pressure inside the chest, decreasing blood return to the chest and decreasing blood flow to the brain.
This is in stark contrast to respiratory arrests, such as drowning, where continued normal cardiac output in the face of inadequate oxygen results in rapid depletion of arterial oxygen content, leading to hypotension and, finally, secondary cardiac arrest. Here ventilatory support is clearly needed, and until better information is available, the AHA's 30:2 ratio is recommended.
One reason the guidelines have not, until now, advocated different approaches to cardiac and respiratory arrests was the assumption that lay individuals could not relate the difference between them. It is important, in training of the public, to emphasize that any person who collapses suddenly, is not responsive and is not breathing normally is indeed a cardiac arrest victim. Be sure to emphasize that there are two types of abnormal breathing: gasping (snoring or agonal respirations), and not breathing at all. Many subjects with witnessed arrests will continue to gasp and provide physiologic ventilation—that is, ventilation with decreased intrathoracic pressures—so that assisted positive-pressure ventilation is not necessary. Or, if allowed, they will begin gasping with CCC CPR (Table 2).4

The cardiocerebral resuscitation protocol8 (Figure 1) is reserved for cases in which an out-of-hospital arrest is presumed to be cardiac in origin—i.e., individuals with sudden, unexpected collapses with absent or abnormal breathing. In all other situations, AHA guidelines for ACLS are used.6,7
EMS should give 200 uninterrupted chest compressions (100 per minute) before each rhythm analysis and single shock, if indicated, followed immediately by another 200 chest compressions and repeat rhythm analysis. Patients are not moved from the scene until three cycles of 200 compressions/rhythm analysis. In most cases they are not transported until they are resuscitated or pronounced dead.7
Initial airway management is delayed until a second rescuer is available and is initially limited to placement of an oral-pharyngeal airway and administration of oxygen by non-rebreather mask. Insertion of an invasive airway and assisted ventilation are not performed until either return of spontaneous circulation or after three cycles of chest compressions, analysis and, when needed, shock. Most who have return of spontaneous circulation (ROSC) are intubated prior to transportation.
When positive-pressure ventilations are delivered, it was initially recommended that they be limited to a rate of 8–10 per minute. There is good evidence that this should be as few as six.
The technique of chest compressions is ideally performed with a metronome attached to the defibrillator to emphasize the importance of a rate of 100 per minute. Full chest recoil after each compression is essential.
If only one responder is on scene, the defibrillator or AED pads are applied before chest compressions are initiated in an effort to minimize the pause between stopping compressions and the defibrillation shock. For CCR, AEDs or their voice instructions need to be reprogrammed.

The latest recommendation in CCR is to advocate establishment of specialized post resuscitation care center where facilities of mild therapeutic hypothermia and specialized care for resuscitated but comatose patients or further management of patients revived of SCA can be done.6

As per the latest AHA recommendations, unconscious adult patients with return of spontaneous circulation (ROSC) should be cooled to 32 c to 34 c for 12 to 24 hours when the initial rhythm is VF (class IIa).

Similar therapy may be beneficial for patients with non-VF arrest out of hospital or for in hospital arrest (Class IIb).

Most clinical studies of cooling have used external cooling techniques (e.g. cooling blanket and frequent application of ice bags) that may require a number of hours to attain target temperature. Most recent studies suggest that internal cooling techniques (e.g. Cold saline, endovascular cooling catheter) can also be used to induce hypothermia. These patients should receive oxygen for first 48 hours whether conscious or comatose. Further, for optimal results with CCR, besides use of therapeutic hypothermia, emergent cardiac catheterization and PCI when appropriate must be included.

These recommendations can benefit patients of SCA. SCA due to ventricular arrhythmias can be delt by a bystander as well as an EMS. Bystander CCR should be instituted at the earliest within 5 minutes of SCA. Successful resuscitation rate can be achieved with minimal interruption of chest compression even by an EMS team. Avoiding early endotracheal intubation, chest compression before and after the shock and early intravenous access are small but very important modifications for EMS CPR. Third and final part of cardiocerebral resuscitation is by and large neglected portion but emphasis has been given to post resuscitation care, including hypothermia, emergent cardiac catheterization and PCI besides establishment of specialized centers. These recommendations are only partly approved as guidelines by AHA. Latest guidelines are expected in 2010 following ILCOR recommendations.