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April 17, 2006 — 编辑小语：心脑复苏术 (CCR) — 运用压胸而无换气法— 改善了院外心脏停止之存活率，此根据Michael J. Kellum医师及其团队发表在4月的美国医学期刊的一篇观察研究；不像传统的心肺复苏术(CPR)是用于心脏和呼吸都停止的时候，CCR运用于目击突如其来的发生心脏停止病患时，心脏停止远比呼吸停止更容易使一个成年人病垮。
动物实验显示，进行CPR之后、决定存活与否的最重要因素是心脏的灌流压，而心脏的灌流压是由连续的压胸达成；而换气却可能造成伤害，因为换气干扰了压胸，降低了静脉血回流心脏，且增加了胸压；威斯康辛州的医务辅助人员使用新的CCR规则，体外电击去颤术前后均进行压胸而不插管或者换气，与使用传统CPR相比，他们提高了300%的存活率。
为了习得此一新规范的更多临床运用，Medscape的Laurie Barclay 访问了此研究的共同作者：Gordon A. Ewy 医师；Gordon A. Ewy医师是土桑市亚利桑那大学心脏救治中心CPR研究小组的创办人暨主任。
Medscape：CCR规范的基本理由为何？
Dr. Ewy：主要的基本理由是CPR 难以发挥功效；院外心脏停止的存活率是极低的，全国平均仅有1%到 3%；尽管定期的更新指导规范，并且尽早电击，存活率仍未改善；数个观察实验一致提供了这个基本理由，让我们思考、得到这个称之为CCR的心脏停止时的新救治法。
病患心脏停止、发生心室纤维颤动(VF)时，尽早电击是重要的，此点广为人知；这也是运用自动体外去颤器(AED)电击去除纤维颤动之原因，当恰当地运用时，在诸如赌场和机场等，显示可以提高存活率。
但VF的早期电生理期仅约5分钟，而紧急救护人员却难以在这段时间内抵达；在这段所谓的心室纤维颤动心脏停止的电生理期之后，病患陷入心室纤维颤动心脏停止的血液动力学期、或称循环期，在此期间，运用AED则难以复苏病患。
在心室纤维颤动心脏停止的循环期，存活的关键因素是藉由压胸迅速重建心脏和脑的灌流压；重建血流可以慢慢地改善心脏停止的不良反应，而使得病患再次对电击产生反应。
我们之所以有兴趣建立新的方法，是因为我们了解到，当有人目击心脏停止案件时、会因为不愿意进行口对口人工呼吸，而不愿为其进行CPR；因此，约八成仅帮忙打119而没有开始为其施以CPR，当救难人员抵达时，为时已晚。
所以，我们的原始问题是，对病患施以压胸是否会比打119后仅在旁观望等候救难人员要更好？1993年时，我们用猪进行研究， 在心室纤维颤动心脏停止的时候，仅用压胸的效果和使用理想的标准之4循环（换气两次后压胸15下）CPR的一样的好，且远比袖手旁观、未进行CPR好；从1993年开始，我们即表示应鼓励大众目击成人心脏停止案件时应对其进行压胸；在1993到1998年间，我们发表了6篇不同的猪只研究，包括一篇是插有气管内管的，均显示单用压胸的效果和理想的标准的CPR一样好，且远比袖手旁观好多了。
在2000年版指导规范出炉后，我们亚利桑那大学心脏救治中心CPR研究小组团队之一，Karl Kern 医师，参加了英国Chamberlain医师及其团队的研究，欲研究如何训练大众、让他们记住并且正确地施作CPR；这个研究的一部分是，他们教导、认证大众操作CPR时录影，他们发现，当进行15下压胸后，平均需要16秒以抬高下巴、靠近鼻子、深呼吸、口对口、吹气和观察胸膛是否进气，之后反覆吹第二口气，然后再继续进行压胸；整个操作CPR过程中，仅有半数时间是在压胸。
之后在2003年发表的猪只CPR研究，当每两次进行15下压胸时被干扰16秒的话，CPR之后24小时存活率仅13%，而若施予连续的压胸则平均存活率可达70% ；此即我们一再提倡目击成人发生心脏停止案件时施作CPR仅需施以压胸的理由。
以下的观察则是由我们的同僚Valenzuela 医师发表；当紧急救护员依照2000年版指导规范操作CPR时，花在压胸的时间也是仅约一半，因为他们把时间花在依照规范操作的其他如插管和协助换气等事项；因此我们结论、提出建议应修订以压胸取代人工呼吸，以改善冠状动脉灌流。
以下的观察发生于土桑市，紧急救护员接获通报到抵达约需时7.5分钟－已非心室纤维颤动心脏停止的电生理期，而是循环期；因此，遵照规范建议立即的电击、并且连续3次电击是有害的，且在电击过程中一再干扰了压胸的进行。
基于上述及其他的观察，我们认为有比这使用40多年的标准CPR更好的复苏方法，我们称之为心脑复苏术，简称CCR，以强调着重在抢救脑部。
Medscape：您最近发表之人体试验研究发现？
Dr. Ewy：我们教了威斯康辛的Mike Kellum 医师和同事们CCR这个新方法，当他们实施时，救活了过去未曾救活的情况；当Kellum 医师和同事们探讨数据时，他们发现，若以2000年版指导规范操作CPR，神经学正常的存活个案为15%，若施以CCR，神经学正常的存活个案则有48%；存活率增加三倍，看起来好到难以置信，但是，无庸置疑的是CCR比CPR更好。
Medscape：CCR的规范和标准的CPR有何不同?
Dr. Ewy：CCR优于CPR的原因之一，据Weisfeldt以及Becker医师的说法，是CCR明确的涵盖了有时间敏感性的心室纤维颤动之三个时期；最初5分钟最重要的是电击去除纤维颤动现象，通常是使用AED施以电击而达到效果；当5分钟过后，纤维颤动的心脏持续消耗着能量，而渐渐虚弱、即便电击仍无法恢复灌流压；由西雅图Cobb医师及其同事、挪威的Wik医师及其同事进行的人体研究显示，在电击前先进行90秒到3分钟的压胸可以有更好的存活率。
因此，CCR规范在电击前以每分钟100下速率压胸200次，而非直接电击；同样重要的，在电击后、确认心脏节率和脉搏前，先继续压胸200次；如此施作的理由，是在实验室实验中，对心室纤维颤动心脏停止者进行一段时间的压胸后电击，几乎都是去纤维颤动，但去纤维颤动仅能恢复脉搏电位活性而无不足以恢复灌流节律；在实验室实验中，我们着眼于压力波，所以我们建议立即重新开始压胸以对心脏灌注血流，使心脏调节之血压渐渐恢复。
CCR最受争议的一点是排除主动正向压力换气；我们延迟或排除由急救人员插管，这点难以对急救人员启齿，但是排除这项处置后可以获致更长的压胸时间。
但是为什么不让急救人员使用面罩与苏醒器帮助病患呼吸呢？对于放置口咽人工气喉、非再吸入式面罩以及无正压高流量给氧，我们的主要理由如下：有正常的呼吸时，胸腔内压减少，但是正压人工呼吸会增加胸腔内压因而降低静脉血回流，这样的情况会使得脑部以及心肌灌流量减少，因此，压胸而无需施以换气可以帮助心肌和脑部有较佳的灌流压而提高存活率。
另一个重要因素，是我们发现急救人员或者医师面对心脏停止的病患时特别激动，反而因施以人工呼吸却造成病患换气过度－平均每分钟换气37次，很难令这些人施救时减少介入的换气次数，除非叫他们完全不对病患施以换气。
令我们知道脑部血液灌流重要性的另一个观察，是西雅图一段藉由电话线上教导操作CPR时的录音；那位妇女在听从电话中的指示操作CPR一段时间后，拿起电话询问道“为什么每次我压他的胸部他就张开眼睛，每次我停止压胸去吹气他就又继续昏睡？”真是一语惊醒梦中人，这位妇女在10分钟内就领悟到我们花了10年研究的东西；一旦停止压胸去做其他任何事情，包括人工呼吸，都会减低脑部血流、对脑部不好。
我最常被问的问题是，血氧程度呢？我的答案是，一旦有了足够的连续的压胸，病患通常会有喘息，而这种临终呼吸提供了合理的血氧程度；缺乏喘息时，血液气体值很糟－但猜猜看怎么了，病患存活；因此医疗和急救人员着迷于人工呼吸以求好的血液气体值，而非着眼于神经学正常存活才是最终的重要目标，这是复苏科学进步的一大阻碍。
Medscape：为何CPR施作不佳？
Dr. Ewy：CPR的谬误在其设计运用于两种完全不同的病态生理学情况：呼吸停止和心脏停止；对其中一种有利的、对另外一种未必如此；这样的规范是认为一般大众不会分辨呼吸停止和心脏停止，我认为他们可以。
试想你把一个人从游泳池拉起来、或者某些人因药物过量停止呼吸，这些情况是呼吸停止；但是目击突如其来的成人昏倒，几乎都是心脏停止；对于心脏停止者最重要的，是持续压胸以求脑部血液灌流，保持脑部以及心脏活着，直到可以施予电击；若有人可以在发作5分钟内使用AED，那很好，但是有两个主要的问题：首先是急救人员通常无法在VF的早期电生理期到达；其次是一般大众不会使用AED；在亚利桑那，注册有超过2500具AED，但据我们所知，仅有10具由一般大众操作。
Medscape：哪种情况是不可以使用CCR的?
Dr. Ewy：对于呼吸停止，你需要的是对他进行人工呼吸；新的CPR指导规范是依照按压胸部30次伴随2次人工呼吸，但是最大的问题是一般大众不愿意口对口施作，所以他们仅仅打119，当等到急救人员抵达时，病患已经死亡。
Medscape：CCR有任何不好的效果吗？
Dr. Ewy：用在目击突如其来的的成人昏倒时，据我所知是没有的。
Medscape：在推广此规范前，有哪些进一步的研究或者教育训练？
Dr. Ewy：我想CCR应广为用于目击突如其来的的成人昏倒，事实上，我想它应该在2003年我们开始这样做的时候就应该被接受。
至于教学，我们应该强调CPR应被保留于运用在呼吸停止；至于目击突如其来的成人昏倒，我们教育一般大众以下3点：首先拨打119，接着开始压胸－即施作CCR，若旁边有其他人，则每人按压100下后互替，因为压胸会很辛苦；最后，若旁边有AED，依照操作说明使用；我相信这种方法可以显著地提高旁观者进行CPR的机率，而因此明显改善存活的机会。
对于急救人员，我想我们必须进行更多研究以决定何时才是绝对必须进行辅助呼吸，我们目前正对此研究中。
Medscape：如果此规范广为使用，您认为对公众健康有何帮助？
Dr. Ewy：美国、加拿大、欧洲最主要的致死原因是突发的心脏停止，CCR显然优于CPR，若CCR广为接受，对公众健康将有显著的正面意义；我们现在已经有了人类试验的数据，且支持我们在动物实验所得的研究发现；我们最近所发表之在人类运用的观察显示，对于有目击的院外心脏停止病患，可以改善300%的神经学正常存活率，且在急救人员抵达时有足堪电击的心脏节律；这研究或许好到难以置信，但是即便仅仅改善10%的存活率，对全球而言仍是一大利多，我深信只要我们遵照CCR指导规范，存活率一定可以比过去40年来好上许多。
Cardiocerebral Resuscitation: A Newsmaker Interview With Gordon A. Ewy, MD
By Laurie Barclay, MD
Medscape Medical News
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 progress in 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 if we 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