A new method for performing cardiopulmonary resuscitation, or CPR, may significantly increase the chances of surviving a cardiac arrest, according to the first large study of the technique in hospitalized patients.
The technique alternates compressions of the chest with compressions of the abdomen to maintain blood flow to the heart and brain. Standard CPR uses compressions of the chest only. Both methods also employ mechanically assisted breathing or mouth-to-mouth breathing.
Researchers at St. Joseph's Hospital and Medical Center in Paterson, N. J., found that 25% of the patients treated with the new CPR technique left the hospital alive, compared to 7% of those treated with the standard technique. The study, involving 135 resuscitation attempts in 103 patients, is being reported today in the Journal of the American Medical Assn.
Dr. Jeffrey B. Sack, the principal author of the study, said he was encouraged by the results but would not recommend a change in CPR procedures based on the results of one study.
"In general, the outcomes (of CPR) are poor," said Sack, who is now a cardiology fellow at UCLA Medical Center. "If we can come up with improved methods that increase the chances of surviving cardiac arrest, we can potentially save many more people."
The New Jersey study is continuing and will be expanded to include other hospitals, Sack said. The research team now has data on about 230 resuscitation attempts in about 200 patients with similar results.
Cardiopulmonary arrest means that the heart stops beating and breathing ceases. The most common reasons are blocked arteries and damage to heart tissue from heart attacks or other problems.
When the heart stops beating, blood flow to the heart and brain must be maintained or irreversible damage and death will occur within minutes. CPR is an interim measure that buys time until electrical shocks or medications can be used to jump-start the heart.
"Basic CPR as we practice it is pretty inefficient," said Dr. Michael Callaham, director of the division of emergency medicine at UC San Francisco. "The amount of blood flow through the heart is a couple percent of normal (during CPR). . . . If this is true, this would be the first significant advance in CPR since it was introduced."
Dr. Richard Cummins of the University of Washington Medical Center in Seattle called the results "encouraging." But Cummins, who is national chairman of the advanced cardiac life support committee of the American Heart Assn., said that it remains to be seen whether the abdominal-compression technique is practical and sufficiently easy to learn for widespread use.
There are also possible complications of the technique, such as the vomiting of stomach contents into the lungs and damage to the liver and spleen. No complications directly related to the procedure were found in the New Jersey study.
In addition, the patients in the New Jersey study are not typical of most patients who suffer cardiac arrest. Most had CPR and other life-support techniques started almost immediately--within 75 seconds of the time their heart stopped beating.
Moreover, all the patients had breathing tubes placed in their tracheae to improve ventilation. When people suffer cardiac arrests outside the hospital, rescuers initially use mouth-to-mouth breathing, which may not be as effective as a breathing tube.
The technique under study is known as "interposed abdominal counterpulsation." It is based on the theory that pressure on the abdominal aorta, the main artery carrying blood to the body, can increase the blood flow resulting from compression of the chest.
The method is similar in principle to a surgical procedure used to help treat some heart surgery patients or those with severe heart attacks, Sack said. This procedure involves the insertion of a balloon pump into the aorta, which automatically inflates after the heartbeat and helps the circulation of blood.
One of the advantages of the new technique is that it does not require any equipment, Sack said.
The New Jersey study was conducted with one person compressing the chest, another compressing the abdomen, and another supplying oxygen to the patient through a tube inserted into the trachea. The abdominal compression rate was equal to the chest compression rate of 80 to 100 per minute.
Sack said the new technique can also be performed by one person and that he and others have done it in this fashion. The person would use one hand to compress to the chest and the other to compress the abdomen. Mouth-to-mouth breathing would be interspersed after a number of chest and abdomen compressions.
Cummins and Callaham, however, said the technique is too complex for one person to perform. They said it would require two or three persons. "It is not that easy. I've done it," Callaham said. "I was surprised how much force it took. . . . It is wishful thinking to think that this can be easily implemented in the majority of circumstances outside of the hospital."
The abdominal compression technique was first tested on dogs in the early 1970s. A 1985 study, conducted in patients who had out-of-hospital cardiac arrests, showed no benefit over standard CPR but was not considered conclusive.
Each year, about 15 million people are trained in basic CPR techniques, Cummins said. The American Heart Assn., the American Red Cross, and other organizations have emphasized teaching people how to recognize the symptoms of heart attacks and how to perform CPR.
Heart disease is the leading cause of death in the United States. Each year, about 1.5 million Americans suffer a heart attack and 500,000 die.
A new technique is being tested to improve the chances of surviving a cardiac arrest. Researchers, however, stress that it is experimental and is not recommended as an alternative to standard cardiopulmonary resuscitation, or CPR.
AB Standard CPR
In standard CPR, compressions of the chest keep blood flowing to the heart and brain until the heartbeat can be jump-started with an electrical shock or medications. When CPR is performed outside the hospital, mouth-to-mouth breathing is used unless trained personnel are available to insert a breathing tube.
ABC The New Technique
In the new method, illustrated here, compressions of the chest are alternated with compressions of the abdomen. The patients in the study all had breathing tubes inserted into their tracheas so that oxygen could be delivered to their lungs.
SOURCE: Journal of the American Medical Assn.