Cardiocerebral Resuscitation: A Newsmaker Interview With Gordon A. Ewy, MD

Laurie Barclay, MD

April 17, 2006

April 17, 2006 Editor's Note: Cardiocerebral resuscitation (CCR) — employing chest compressions but no ventilations improves survival of out-of-hospital cardiac arrest, according to the results of an observational study published by Michael J. Kellum, MD, and colleagues in the April issue of the American Journal of Medicine . Unlike traditional cardiopulmonary resuscitation (CPR), which was designed both for cardiac and respiratory arrest, CCR is designed only for unexpected, witnessed, cardiac arrest, which is by far more common than respiratory arrest as a cause of sudden collapse in adults.

Animal experiments showed that the most important factor determining survival after CPR is cardiac perfusion pressure, achieved by continuous chest compressions. Ventilations may actually be harmful because they interrupt chest compressions, decrease venous return to the heart, and increase intrathoracic pressure. When paramedics in Wisconsin employed the new CCR protocol, with chest compressions before and after defibrillation but no intubation or ventilations, they achieved a 300% increase in survival compared with use of traditional CPR.

To learn more about the clinical implications of this new protocol, Medscape's Laurie Barclay interviewed study coauthor Gordon A. Ewy, MD, director and pioneer of the CPR Research Group at the University of Arizona Sarver Heart Center in Tucson.

Medscape: What was the rationale behind the CCR protocol?

Dr. Ewy: The major rationale is that CPR hardly ever works. The survival of out-of-hospital cardiac arrest is dismal, averaging 1% to 3% nationwide. And in spite of periodic updates in guidelines, with the exception of early defibrillation, survival has not improved. Several experimental observations, when correlated, provide the rationale for a new approach to cardiac arrest, which we call CCR.

It is well known that in patients with cardiac arrest secondary to ventricular fibrillation (VF), early defibrillation is the most important intervention. This is why the defibrillation shock from an automated external defibrillator (AED), when promptly applied, has been shown to improve survival in selected locations such as casinos, airports, and the like.

But it turns out that this early "electrical phase" of VF arrest lasts for only about 5 minutes, and emergency medical personnel hardly ever arrive during this time frame. After this so-called electrical phase of VF cardiac arrest, the patient enters the hemodynamic or circulatory phase of VF arrest. And during this phase, applying an AED hardly ever resuscitates the patient.

During the circulatory phase of prolonged cardiac arrest due to VF, the factor critical to survival is the prompt restoration of cardiac and cerebral perfusion pressures by chest compressions. Restoration of blood flow might slowly reverse the adverse effects of cardiac arrest so that the individual will again respond to defibrillation.

Our interest in alternative approaches to the international guidelines began with the realization that most people who witness a cardiac arrest will not initiate bystander CPR because they do not want to do mouth-to-mouth resuscitation. Therefore, about 80% just call 911 and do not begin bystander CPR. By the time the paramedics arrive, it's too late.

So our original question was whether doing chest compressions alone on people who collapse is better than calling 911 and doing nothing until the paramedics arrive. Our swine studies in 1993 showed that during prolonged VF arrest, chest compressions alone are just as good as ideal, standard CPR when we took 4 seconds for the 2 recommended ventilations before each 15 chest compressions, and much better than no bystander CPR. Since 1993 we've been saying that we should encourage the lay public to do chest compressions–alone CPR on adults with witnessed, unexpected collapse. Between 1993 and 1998, we published 6 different swine studies, including one study with the endotracheal tube clamped, all showing that chest-compression alone was equal to ideal standard CPR, and dramatically better than doing nothing.

After the 2000 guidelines came out, Dr. Karl Kern, who is part of our University of Arizona Sarver Heart Center CPR research team, participated in a study with Dr. Chamberlain and colleagues from England to determine how to get lay people to remember and correctly perform CPR after they've been trained. As part of this study, they did videos on certified lay people doing rescue CPR, which showed that after they did 15 chest compressions, it took an average of 16 seconds for them to lift the chin, close the nose, take a breath, make a mouth-to-mouth seal, blow and watch the chest expand, repeat rescue breathing for a second breath and return to chest compressions. So they were pressing on the chest for only half the time that they were doing CPR.

In a subsequent swine CPR study published in 2003, we showed that when chest compressions are interrupted for 16 seconds between each 15 chest compressions, 24-hour survival after CPR was only 13% compared to an average of 70% in our swine given continuous chest-compression CPR. This is one reason why we have advocated and continue to advocate chest compression–only bystander "CPR" for witnessed sudden collapse in an adult.

The next observation was published by our colleague Dr. Valenzuela. When paramedics perform CPR following the 2000 guidelines, they spend only half the time on chest compressions because of the time they spend on other guideline-advocated activities, including intubation and ventilation. We therefore concluded that the recommended alternating chest compressions with breathing should be revised to improve coronary perfusion.

The next observation was that in Tucson, the emergency medical personnel arrived at an average of 7 and a half minutes [after collapse] — not in the electrical phase of VF arrest, but in the circulatory phase. Thus, following the guidelines which advocated immediate defibrillation and 3 series of defibrillation was deleterious, as chest compressions were interrupted for inordinate periods of time while the AED analyzed, shocked, and analyzed.

Because of these and other observations, we concluded that there is a better way to do resuscitation than the standard CPR advocated for the last 40 years. We called the new method cardiocerebral resuscitation, or CCR, to emphasize the importance of saving the brain.

Medscape: What were the findings of your recently published study in humans?

Dr. Ewy: We taught Dr. Mike Kellum and associates in Wisconsin the new method of CCR. When they implemented it, the paramedics would comment that they were having "saves" that they would never have had before. When Dr. Kellum and associates looked at the data, they found that neurologically normal survival improved from 15% with standard 2000 guidelines CPR to 48% with CCR. This 300% increase in survival in this study is almost too good to believe, but there is no doubt in our minds that CCR is definitely better than CPR.

Medscape: How does this protocol differ from standard CPR?

Dr. Ewy: One of the reasons that the CCR protocol is better than the standard CPR protocol is because it recognizes the 3-phase, time-sensitive model of VF articulated by Drs. Weisfeldt and Becker. The most important intervention in the first 5 minutes is defibrillation, which is why implanted cardioverter defibrillators and AEDs are effective. After the first 5 minutes, the fibrillating heart continues to use up its energy stores, becomes weaker, and cannot generate a perfusion pressure even if defibrillated. Studies in humans by Dr. Cobb and associates from Seattle, and Dr. Wik and associates from Norway showed that if one does chest compressions for 90 seconds to 3 minutes before defibrillation, survival is better.

Therefore, rather than immediate defibrillation, the CCR protocol incorporates 200 compressions at 100/minute before defibrillation. Equally important, it also incorporates 200 chest compressions immediately after the defibrillation, prior to rhythm analysis and pulse check. The reason for this is that in our experimental laboratory, after prolonged chest compressions for VF arrest, the shock almost always defibrillates, but defibrillates the rhythm to pulseless electrical activity and not to a perfusing rhythm. In our experimental laboratory, we are looking at the pressure waves, so we immediately restart chest compressions to perfuse the heart, and the cardiac-generated blood pressure gradually returns.

The most controversial aspect of CCR is the elimination of active positive pressure ventilations. We first delayed or eliminated intubation by the paramedics.This is a hard sell to paramedics. But this eliminated one intervention that resulted in a prolonged interruption of chest compressions.

But why not let the paramedics or emergency medical service personnel ventilate with bag-valve-mask ventilation? The rationale for our approach of placing an oropharyngeal airway, a nonrebreather mask, and high-flow oxygen without positive pressure is as follows. With normal breathing, intrathoracic pressure decreases, but positive pressure ventilating increases intrathoracic pressure and thereby decreases venous return. The result is decreased cerebral and myocardial perfusion. Thus, chest compression without ventilation results in better myocardial and cerebral perfusion pressures and increases survival.

Another important factor is that we and others have shown that physicians and paramedics are so excited during a cardiac arrest that they overventilate — an average of 37 ventilations/minute. It is very difficult to get these individuals to ventilate less, unless you do not have them ventilate at all.

Another observation that taught us the importance of cerebral perfusion was listening to a recording of a lay rescuer in Seattle doing dispatch-directed CPR. After a while, the woman returned to the phone and asked, "Why is it that every time I press on his chest he opens his eyes, and every time I stop to breathe for him he goes back to sleep?" Out of the mouths of babes! That woman learned in 10 minutes what it took us 10 years to find out. Whenever you stop chest compression to do anything, including breathing, it is bad for the brain as it reduces blood flow to the brain.

The question that I am most often asked is what happens to the blood oxygenation? My answer is that if one does adequate continuous chest compressions, the individual often gasps and this agonal type breating provides reasonable oxygenation. In the absence of gasping, the blood gases are very bad — but guess what, the individual survives. Thus, the medical and paramedical obsession with blood gases and thus ventilation, and not looking at neurologically normal survival as the most important end point, has been one of the major impediments to progressin resuscitation science.

Medscape: Why doesn't CPR work well?

Dr. Ewy: The fallacy of CPR is that it was designed for 2 totally different pathophysiological situations: respiratory arrest and cardiovascular arrest. What is beneficial for one may not be for the other. The reason for a single approach is that it was, and to many still is, thought that the lay public cannot tell the difference between a respiratory arrest and a cardiac arrest. I think they can.

If you pull someone out of a swimming pool, or if they stop breathing after a drug overdose, that's a respiratory arrest. But an unexpected, witnessed collapse in an adult is almost always cardiac arrest. The most important intervention for cardiac arrest is continuous chest compressions to perfuse the brain, to keep the brain and heart alive until you can shock it. If one can use the AED in the first 5 minutes, that's fine, but there are 2 major problems: the first is that the paramedics usually do not arrive in the electrical phase of VF, and the second is that the lay public does not use the AED. In Arizona, over 2,500 AEDs are registered, and we have knowledge of only 10 being used by the lay public.

Medscape: Are there situations in which the CCR protocol should not be used?

Dr. Ewy: For respiratory arrest, you need to breathe for the person. The new CPR guidelines should be followed: 2 breaths alternating with 30 compressions. But the major problem is that most lay people won't do mouth-to-mouth, so they just call 911, and by the time the paramedics get there, the person is dead.

Medscape: Are there any negative effects of CCR?

Dr. Ewy: Not that I know of, if it is used on adult subjects with witnessed, unexpected collapse.

Medscape: What additional research, education, and training needs to be done before this protocol is widely adopted?

Dr. Ewy: I think CCR should be widely adopted right now for unexpected, witnessed collapse in adults. In fact, I think it should have been adopted in 2003, when we did.

As for teaching, we should emphasize that CPR should be reserved for respiratory arrest. But for witnessed, unexpected collapse in an adult, we teach laypeople a 3-step protocol: first, call 911; second, start chest compression–only CCR. If another person is available, each do 100 compressions and trade off, as continuous chest compressions is hard work. Third, if there is an AED around, put it on and follow the directions. I think this approach should markedly increase the prevalence of bystander CPR, and bystander CPR significantly improves the chance of survival.

For paramedics, I think we need to do more research to determine when assisted ventilation is absolutely necessary. We are doing such studies now.

Medscape: If the protocol is widely implemented, what effect do you believe it will have on public health?

Dr. Ewy: The most common cause of death in the United States, Canada, and Europe is sudden cardiac arrest. CCR is significantly better than CPR, and if it's widely adopted, it will have a significant positive effect on public health. We now have data in humans to support what we've found in our animal experiments. Our recently published observations in humans showed a 300% improvement in neurologically normal survival in patients with witnessed out-of-hospital cardiac arrest and a shockable rhythm when the paramedics arrived. This study is almost too good to believe, but ifwe can improve survival even by 10%, there will be a huge benefit worldwide. I know if we follow these CCR guidelines, survival is going to be a lot better than it has been for the last 40 years.

Am J Med . 2006;119:335-340

Reviewed by Gary D. Vogin, MD


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