Chest-Compression-Only CPR Should Be Recommended

Emergency medical services shouldn't advise bystanders to perform CPR with mouth-to-mouth

16 oct 2010-- Chest-compression-only cardiopulmonary resuscitation (CPR) should be recommended by emergency medical services to bystanders caring for individuals experiencing out-of-hospital cardiac arrest rather than standard CPR with mouth-to-mouth, according to research published online Oct. 15 in The Lancet.

Michael Hupfl, M.D., of Medical University of Vienna in Austria, and colleagues systematically reviewed studies in which chest-compression-only bystander CPR was compared with standard bystander CPR for adult patients with out-of-hospital cardiac arrest. The investigators completed a primary meta-analysis in which patients were randomized to receive one of the two CPR techniques, as well as a secondary meta-analysis of observational cohort studies.

In the primary meta-analysis, using pooled data from three randomized trials, the investigators found that chest-compression-only CPR was associated with an improved chance of survival as compared with standard CPR (14 percent versus 12 percent). The data also revealed that the absolute increase in survival was 2.4 percent and the number needed to treat was 41. No difference was found between chest-compression-only CPR and standard CPR in the secondary meta-analysis of seven observational cohort studies.

"Our findings support the idea that emergency medical services dispatch should instruct bystanders to focus on chest-compression-only CPR in adults with out-of-hospital cardiac arrest," the authors write. "However, whether chest-compression-only CPR should be recommended for unassisted lay bystander CPR is unclear."

One author disclosed financial ties to Roche Diagnostics and Gerson Lehrman Group, and another disclosed financial ties to St John's Ambulance Service in Vienna and Novo Nordisk.

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CPR is successful without mouth-to-mouth, but not without oxygen

COLUMBUS, Ohio, 30 nov 2009 – People can survive cardiac arrest if they receive only chest compressions during attempts to revive them – as advised by the current American Heart Association guidelines. But they cannot survive without access to oxygen sometime during the resuscitation effort, research suggests.

Scientists tested different scenarios in an animal study of cardiac arrest. Rats received either 100 percent oxygen, 21 percent oxygen – the equivalent of room air – or no oxygen (100 percent nitrogen) at the same time they received cardiopulmonary resuscitation (CPR).

About 80 percent of the rats survived regardless of the percentage of oxygen they received along with chest compressions. However, in the group receiving no oxygen, only one animal could be resuscitated.

Though these animals received the oxygen via ventilation, people who suffer cardiac arrest in a public setting would more likely obtain some oxygen by gasping during CPR or by receiving some air from a vacuum effect resulting from chest compressions, researchers say.

"The study showed that there is a need for oxygen. How much oxygen is needed remains unknown. There is probably a sweet spot in there somewhere," said Mark Angelos, professor of emergency medicine at Ohio State University and senior author of the study.

"For the first few minutes, it's probably right just to push on the chest. But at some point you probably need to add oxygen, however you can – maybe mouth-to-mouth or with supplemental oxygen. Where that sweet spot is is not yet clear."

The research is published in a recent issue of the journal Resuscitation.

According to the American Heart Association, almost 80 percent of cardiac arrests that take place outside a hospital occur at home and are witnessed by a family member. Yet only 6.4 percent of sudden cardiac arrest victims survive because most witnesses do not know how to perform CPR.

The association is in the midst of a new campaign touting "hands-only" CPR, urging people to call 911 and push "hard and fast" in the center of the chest of a person in cardiac arrest.

Angelos said his research is not intended to counter the current guidelines. Instead, scientists continue to study the intricacies of the resuscitation process in the pursuit of ways to improve the potential for survival after cardiac arrest.

Approximately 30 percent of cardiac arrest patients will survive long enough to be hospitalized. But far fewer are ever discharged from the hospital; most typically die of heart failure or brain damage resulting from an extended loss of oxygen to the brain, said Angelos, also an investigator in Ohio State's Davis Heart and Lung Research Institute.

In the study, Angelos and colleagues imposed six minutes of cardiac arrest on 33 rats before CPR was started. During CPR, animals were ventilated with either 100 percent oxygen or 21 percent oxygen.

A control group of rats received nitrogen, which eliminated oxygen from their lungs. This scenario allowed for lab comparisons, but was not intended to mimic normal conditions because people would likely have some residual oxygen in their lungs and blood even during cardiac arrest.

CPR was continued until the surviving animals experienced what is called the "return of spontaneous circulation," when the heart pumped blood on its own. All animals receiving oxygen returned to spontaneous circulation at approximately the same time, between about 90 seconds and two minutes after CPR began.

All surviving animals continued to receive the same levels of oxygen that they had received during CPR for two minutes after their hearts started working, and then they were all transferred to 100 percent oxygen for an hour.

"That's pretty typical for a hospitalized cardiac arrest victim, to get a high concentration of oxygen early on," Angelos said.

One rat unexpectedly survived CPR without any oxygen, but died within 72 hours. Among the rats receiving oxygen during CPR, nine of 11 (82 percent) of the rats in the 21-percent oxygen group survived CPR, and 10 of 12 (83 percent) of the rats receiving 100 percent oxygen survived. At the 72-hour mark, those figures had dropped: 77 percent of the room-air rats were still alive, and 80 percent of 100-percent oxygen rats were still living.

Neurological tests showed that five of seven (71 percent) of the room-air rats and three of eight (38 percent) of the rats on 100-percent oxygen during CPR returned to normal brain function at 72 hours. The researchers considered these findings secondary to the initial finding that oxygen was required for success during the initial resuscitation process, Angelos noted.

"In a public setting, presumably we don't have any options. We see that ventilating with room air is just as good as supplemental oxygen," he said. "However, we also know now that too little or the absence of any ventilation might be harmful, at least over time, due to the lack of oxygen."

Generally, Angelos noted, the concern has been too much ventilation, which lessens the effectiveness of CPR.

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This work was supported by the American Heart Association, Great Rivers Affiliate.

Angelos conducted the research with Steven Yeh, Rebekah Cawley and Sverre Aune of Ohio State's Department of Emergency Medicine; Yeh and Aune also are researchers in the Davis Heart and Lung Research Institute and Ohio State's Biophysics Graduate Program.

More Chest Compressions in CPR May Improve Survival

Researchers urge changes to resuscitation practices to maximize chest compression in CPR

16 sept 2009-- The more that emergency personnel perform chest compression during cardiopulmonary resuscitation (CPR) of a patient in cardiac arrest, the greater the odds of patient survival, according to a study published online Sept. 14 in Circulation.

Jim Christenson, M.D., of the University of British Columbia in Vancouver, Canada, and colleagues studied a cohort of 506 patients who suffered out-of-hospital cardiac arrest due to ventricular fibrillation or ventricular tachycardia and did not undergo defibrillation before electronically-monitored CPR was performed. The researchers assessed the relationship between the fraction of time spent on chest compression (CCF) and patient survival to hospital discharge.

Generally, the researchers found that the adjusted odds ratio for survival increased with increased CCF. For 0 to 20 percent CCF, (reference); for 21 to 40 percent CCF, odds ratio, 2.27; for 41 to 60 percent CCF, odds ratio, 2.39; for 61 to 80 percent CCF, odds ratio, 3.01; and for 81 to 100 percent CCF, odds ratio, 2.33. The researchers attributed the drop in odds ratio in the highest CCF category to a plateau effect above 80 percent CCF or a patient group in which there was less likelihood of survival and more extreme resuscitation efforts.

"These data strongly support the contention that more time spent performing chest compressions in the early phase of resuscitation substantially affects survival to hospital discharge. Implementation of strategies to alter resuscitation practices to maximize chest compression fraction are likely to result in a real and sustainable increase in survival from cardiac arrest," the authors write.

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Hospital Resuscitation Hasn't Improved Survival in Elderly

Fewer than one in five patients survive to hospital discharge; survival is even lower in certain groups

05 july 2009 -- Among elderly patients who undergo in-hospital cardiopulmonary resuscitation, overall survival rates have not improved since the early 1990s, and survival is especially low in men and minorities, according to a study published in the July 2 issue of the New England Journal of Medicine.

William J. Ehlenbach, M.D., of the University of Washington in Seattle, and colleagues analyzed 1992 to 2005 fee-for-service Medicare data and identified 433,985 patients who underwent in-hospital cardiopulmonary resuscitation, only 18.3 percent of whom survived to discharge.

Although the survival rate did not significantly change during the study period, the researchers observed an increase in the proportion of patients who underwent in-hospital cardiopulmonary resuscitation before death. They also found that older age, male sex, chronic disease burden, admission from a skilled nursing facility, and African-American or other non-Caucasian race were associated with poorer survival. Compared to similar Caucasian patients, African-Americans had 23.6 percent lower adjusted odds of survival, a finding partly explained by hospital effects.

"This study provides information useful to older patients and their clinicians in their decision about whether to choose to be resuscitated, since the proportion of elderly patients who choose resuscitation is directly related to the probability of survival that is presented to these patients," the authors conclude. "Our findings also provide a stimulus to understand the association between race and survival, with the goals of not only eliminating racial disparities in the quality of medical care but also understanding factors associated with the incidence of cardiopulmonary resuscitation."

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New CPR promises better results by compressing abdomen, not Chest

Leslie Geddes, the Showalter Distinguished Professor Emeritus in Purdue's Weldon School of Biomedical Engineering, demonstrates a new technique for performing cardiopulmonary resuscitation. The method promises to be more effective than...
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WEST LAFAYETTE, Ind. - A biomedical engineer at Purdue University has developed a new method to perform cardiopulmonary resuscitation that promises to be more effective than standard CPR because it increases nourishing blood flow through the heart by 25 percent over the current method.
A new technique is desperately needed because conventional CPR has a success rate of 5 percent to 10 percent, depending on how fast rescuers are able to respond and how well the procedure is performed. For every one minute of delay, the resuscitation rate decreases by 10 percent.
"In other words, at 10 minutes, the resuscitation is absolutely ineffective," said Leslie Geddes, Showalter Distinguished Professor Emeritus in Purdue's Weldon School of Biomedical Engineering. "Any medical procedure that had that low a success rate would be abandoned right away. But the alternative is not very good, either: Don't do CPR and the person is going to die."
Geddes has developed the first new CPR alternative, called "only rhythmic abdominal compression," or OAC-CPR, which works by pushing on the abdomen instead of the chest.
"There are major problems with standard CPR," Geddes said. "One is the risk of breaking ribs if you push too hard, but if you don't push hard you won't save the person. Another problem is the risk of transferring infection with mouth-to-mouth breathing."
The new CPR method eliminates both risks, Geddes said.
Findings will be detailed in a research paper appearing this month in the American Journal of Emergency Medicine, published by Elsevier Inc. The paper was authored by Geddes and his Purdue colleagues Ann E. Rundell, assistant professor of biomedical engineering, biomedical engineering doctoral student Aaron Lottes, and basic medical sciences graduate students Andre Kemeny and Michael Otlewski.
In standard chest-compression CPR, which has been in practice since the 1960s, the rescuer pushes on the chest and blows into the subject's mouth twice for every 30 chest compressions. However, the risk of infection is so grave that many doctors and nurses often refuse to administer mouth-to-mouth resuscitation. In one 1993 study of 433 doctors and 152 nurses, 45 percent of doctors and 80 percent of nurses said they would refuse to administer mouth-to-mouth resuscitation on a stranger.
"This is the real world that nobody knows about, and it's a sobering thought," Geddes said.
OAC-CPR eliminates the need to perform mouth-to-mouth resuscitation.
The American Heart Association requires that rescuers administering CPR push with enough force to depress the chest 1 and a half to 2 inches at a rate of 100 times per minute.
"To depress the chest 1.5 to 2 inches takes 100 to 125 pounds of force," Geddes said. "So you have to push pretty hard and pretty fast, and two people are needed to perform it properly. One blows up the lungs and the other compresses the chest. And when the one who's compressing the chest gets tired, they change positions."
OAC-CPR requires only one rescuer.
Instead of two breaths for every 30 chest compressions, the new procedure provides a breath for every abdominal compression because pushing on the abdomen depresses the diaphragm toward the head, expelling air from the lungs. The release of force causes inhalation.
Researchers have known since the 1980s that pushing on the abdomen circulates blood through the heart. The idea was originated by Purdue nursing doctoral student Sandra Ralston, Geddes said.
"She made the remarkable observation that if you pushed on the abdomen after each chest compression you could double the CPR blood flow," he said. "So I started thinking, what would happen if you just pushed on the abdomen and eliminated chest compression entirely""
The procedure provides a new way to effectively perform "coronary perfusion," or pumping blood through the heart muscle, which is critical for successful resuscitation because the heart muscle is nourished by oxygenated blood, Geddes said.
"Unfortunately, in standard chest-compression CPR, blood sometimes flows in the wrong direction, which means the coronary blood flow goes backward, bringing de-oxygenated blood back into the heart muscle," Geddes said. "This retrograde flow reduces the likelihood of resuscitation."
Findings showed that OAC-CPR eliminates this backward flow.
The Purdue researchers compared coronary artery blood flow during standard chest-compression CPR with the flow resulting from only abdominal compression CPR. Findings showed that using the new method and pushing with the same force recommended for standard CPR provided 25 percent more blood flow through the heart muscle without retrograde flow in the coronary arteries.
The researchers followed the standard recommended by the American Heart Association, pushing with 100 pounds of pressure 100 times per minute.
"With OAC-CPR, you really don't have to press as hard or as often, but we followed the American Heart Association standard to avoid possible criticism from people who could have said we didn't observe the standard," Geddes said.
Another benefit of OAC-CPR is that it eliminates rib fractures, which are commonly caused by compressing the chest. Rib fractures cause the chest to recoil more slowly, but effective CPR requires that rescuers wait until the chest recoils fully before compressing.
Geddes created a wooden "pressure applicator" that resembles a scaled-down version of a baseball home plate. It is contoured so that it can be used to compress the abdomen without pushing on the ribs. However, a rescuer could push with the hands to perform the procedure if no applicator were available.
Abdominal organs contain about 25 percent of the total blood volume in the body.
"You can squeeze all of that into the central circulation when you press on the abdomen," Geddes said.
Whether the procedure gains widespread acceptance depends on whether other researchers can duplicate the results.
"In research, you publish data and then the scientific community looks at the data and tries to duplicate it to verify that it works," said Geddes, who was awarded the National Medal of Technology from President George W. Bush in a White House ceremony on July 27. It is the nation's highest honor for technological innovation.