Cardiopulmonary resuscitation is often done improperly by rescuers who give too few chest compressions and the wrong amount of ventilation.
Those are the findings of two new studies that are among the first to precisely measure the performance of CPR in real-life situations, both inside and outside the hospital.
CPR has been around for about 50 years, and CPR guidelines are frequently revised. But until now, there has not been a reliable, objective way to measure how well it is being performed, said Lance B. Becker, M.D., a coauthor of the in-hospital study and a professor of emergency medicine and director of the Emergency Resuscitation Research Center at the University of Chicago.
“Now we find that CPR is not being done very well,” he said.
The two studies' investigators used a new monitor/defibrillator device that can count how often compressions are given and how much pressure is exerted with each compression. The device, developed by a Norwegian company, also records the rate of volume of ventilations.
In the in-hospital study, Dr. Becker and his colleagues examined the use of the device in 67 cardiac arrest cases. All the rescuers had received proper training in CPR. Guidelines call for 100 compressions per minute and 12-16 ventilations per minute, but in 28% of the cases, the average compression rate was less than 90 compressions per minute during the first 5 minutes of resuscitation. In 61% of the 30-second segments studied, the ventilation rate was more than 20 ventilations per minute. Moreover, 37% of the compressions were too shallow (JAMA 2005;293:305-10).
The out-of-hospital study looked at use of the device in 176 patients who went into cardiac arrest in three European cities and were attended by paramedics or by a nurse anesthetist.
The researchers found that 48% of the times that the rescuers were performing resuscitation, they were not actually giving compressions. When they did perform compressions during the CPR episode, they gave compressions at a rate of 121 per minute—close to the study's target values of 100-120 compressions per minute. But the average number of compressions delivered in a minute was only 64. Rescuers gave an average of 11 ventilations per minute (JAMA 2005;293:299-304).
Neither study was able to look precisely at whether poor performance of the CPR affected patient survival, because neither had enough patients to make that determination. However, in the study performed by Dr. Becker and his colleagues, the investigators did note that patients who had longer intervals without chest compression had worse resuscitation results.
Speaking at the 2004 American College of Emergency Physicians Scientific Assembly, Dr. Becker noted that he and his colleagues have performed another study, of 100 patients, in which the compression rate was counted and recorded by a trained nurse at the scene. In that study, he said, those patients who received 80-100 compressions a minute were significantly more likely to survive than those who did not.
The results of the in-hospital and out-of-hospital CPR studies are not surprising, noted an editorial that accompanied the studies (JAMA 2005;293:363-5). Prior studies have shown low chest compression rates and high ventilations rates, and they have also shown that CPR training is poorly retained, said Arthur B. Sanders, M.D., in the editorial.
The studies suggest that CPR and advanced cardiac life support (ACLS) training need to be simplified to stress managing cardiac arrest and to emphasize compression over breathing, said Dr. Sanders of the department of emergency medicine at the University of Arizona, Tucson.
ACLS training has become more and more complicated over time so that it now includes instruction on stroke and shock and even managing electrolyte imbalances and asthma, he said.
Both the American Heart Association and the International Liaison Committee on Resuscitation are due to update their CPR and emergency cardiovascular care guidelines in the coming year, Dr. Sanders noted. He called on the groups to simplify their guidelines, and to “return to the core mission” in ACLS training.
“It is time to simplify the CPR guidelines and educational programs so that all patients who sustain cardiac arrest can receive optimal treatment,” Dr. Sanders said.
Dr. Becker said the device used in his study could also be a major aid in improving resuscitation efforts because it can tell someone administering CPR when they need to speed up their compressions and when they need to slow down their breathing.
Dr. Becker disclosed financial relationships with a series of companies involved in developing the device and is a paid consultant to two of them.