February 3, 2005
Vol. 24 No. 9

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    Device aids researchers in measuring medical personnel’s CPR application

    By John Easton
    Medical Center Public Affairs

    New technology has allowed researchers at the University to measure, for the first time, how closely well-trained hospital staff comply with established guidelines for cardio-pulmonary resuscitation. The results reveal room for improvement.

    In the Wednesday, Jan. 19 issue of the Journal of the American Medical Association, the researchers show that, even in a hospital setting, chest compressions during CPR often are performed too slowly, are too shallow and too frequently interrupted, and ventilation rates usually are too high. A second study assessing out-of-hospital CPR by paramedics and nurse anesthetists in three European cities found even greater deviation from the guidelines, suggesting that the problem is endemic.

    “CPR has been around for 50 years, but until now, we haven’t had a precise, reliable way to assess how well it’s being done,” said study author Lance Becker, Professor of Emergency Medicine and Director of the Emergency Resuscitation Research Center at the University. “Now we find that it’s not being done very well.”

    The two JAMA studies “document a major problem in the treatment of cardiac arrest,” notes an editorial that accompanies the papers, adding that “this conclusion is not surprising.”

    “You can’t fix what you can’t measure,” Becker said. “Performing CPR was like driving a car without a speedometer, based more on feel than on feedback. Now, with a device that tells us how fast we are going, we think we can rein in the speeders and speed up those who fall behind.”

    The key to this study was an investigational monitor/defibrillator device that records the rate and depth of chest compressions, the rate and volume of ventilations, and the presence or absence of a pulse. It also notes when no compressions are being performed and calculates total “no-flow” time, as well as the fraction of time during a cardiac arrest when there is no blood flow.

    In this study, the cardiac arrest response team at the University Hospitals used the device to measure the quality of CPR during the first five minutes of each resuscitation attempt on 67 patients who suffered a cardiac arrest at the Hospitals between Dec. 11, 2002, and April 5, 2004. The results, which were broken down into 30-second segments, were compared to guidelines the American Heart Association developed.

    The guidelines recommend 100 chest compressions per minute to a depth of at least 38 millimeters (about 1.5 inches). They call for a ventilation rate of 12 to 16 breaths a minute, and they advise keeping the no-flow fraction—the fraction of time in cardiac arrest without chest compressions—under 0.17 (about 10 seconds out of every minute.)

    In 28 percent of the cases, chest compression rates fell below 90 per minute. Thirty-seven percent of the chest compressions were too shallow. Ventilation rates were usually too high; in 61 percent of the 30-second segments, ventilation rates were over 20 per minute. In 40 percent of cases, the no-flow fraction rose above 0.20.

    Multisite studies by the same team, although preliminary, have found similar rates in other hospital settings and among paramedics in the field.

    The device that uncovered the problem, however, may help solve it. A follow-up study already is underway at the University Hospitals, in which a second-generation device not only measures compliance, but also provides immediate feedback, prompting the resuscitation team to adjust compression speed or depth and ventilation rate.

    “This immediate feedback,” Becker said, “may help us improve the quality of CPR and potentially increase survival rates.”

    “Unfortunately, we cannot yet say how much of a difference that will make,” he added. “The official guidelines define what we consider optimal, but this was the first effort to study compliance with those guidelines in a real-life setting, and no one has ever demonstrated a difference caused by deviation from the guidelines.”

    This pilot study was too small to show a detectable difference in results between optimal and flawed CPR. Survival rates were just as good for patients receiving imperfect CPR as for those where performance exactly matched the guidelines.

    But CPR does make a difference, as it “buys you time,” explained Benjamin Abella, Assistant Professor in Medicine and lead author of the study. “It protects your heart and brain until we can get your heart pumping again.”

    The study authors have used their data to launch an effort to increase the quality of CPR delivered at the hospital. They aim to combine additional training for CPR teams with widespread use of the measurement device, which provides text and spoken prompts for the user on how to improve performance during the process.

    “Learning how to measure quickly and accurately showed us that we had a problem,” said Becker. “But it also provides us with at least part of the solution, a real-time critique that can catch and correct common mistakes before they do any harm. This should help tighten up one link of the chain.”

    The consistency of poor CPR performance also suggests the need to revise the guidelines, Arthur Sanders and Gordon Ewy of the University of Arizona College of Medicine argue in their editorial.

    The guidelines “are too complex,” they wrote, and need to be simplified “so that all patients who sustain cardiac arrest can receive optimal treatment.”