Study finds little benefit in CPR device

September 2, 2011
Study finds little benefit in CPR device
By John Fauber | McClatchy-Tribune News Service

MILWAUKEE — A large clinical trial led by researchers at the Medical College of Wisconsin of a CPR device to treat cardiac arrest failed to show a survival benefit, but the study's lead author said he believes combining the device with another CPR device eventually will save lives.

The newest development involves a study published in Thursday's issue of the New England Journal of Medicine.

The study involved about 9,000 cardiac arrest patients in the U.S and Canada who received either an airway device known as the ResQPOD or a sham device that looks like the ResQPOD, but provides only standard resuscitation.

The ResQPOD is a one-way valve attached to a face mask or an endotracheal tube and is used with a ventilation bag. It essentially blocks air from entering the lungs during the decompression phase of CPR, thereby creating a vacuum in the lungs. That creates suction, which draws more deoxygenated blood back from the veins of the arms and legs, which, in turn, allows for more blood flow going out, especially to the brain.

Early research suggested it improved survival in cardiac arrest, which causes 330,000 deaths a year when occurring outside of a hospital.

However, the new study found no significant survival benefit. About 6 percent of patients in both arms of the study survived to be discharged from a hospital with satisfactory ability to function in daily activities.

Lead author Tom Aufderheide, a professor of emergency medicine with Medical College, said he was disappointed with the results.

However, he said he believes the device saves lives when it is used immediately. He said Froedtert Hospital, where he practices, continue to use the device.

Other doctors said they believe the trial failed to show a benefit because it was designed in a way that resulted in delays in using the device once CPR had started.

The delays in adding the device to CPR amounted to several minutes in some cases, said Marvin Wayne, medical program director for Emergency Medical Services in Bellingham/Whatcom County, Wash.

"Quality CPR has to start now, not in five minutes or 15 minutes," said Wayne, an associate clinical professor with the University of Washington who was not involved in the latest study.

Wayne and Aufderheide said they believed that substantial improvements in survival can be obtained when the device is used with another CPR device, known as the ResQPump.

The ResQPump enhances chest compression and decompression by use of a suction cup with handles that is placed over the chest. Lifting up on the handles enhances suction in the chest, pulling more blood back to the heart, allowing more oxygenated blood to be pumped out to the body and brain.

The ResQPOD already is approved for use in the U.S. The ResQPump is not.

In January in The Lancet, a separate study that combined the two devices showed a 50 percent survival improvement when paramedics used the combined devices compared with standard CPR.

Nine percent of those treated with the combined devices were discharged from the hospital with favorable neurological function, compared with 6 percent of those receiving standard CPR. Favorable was defined as being able to live independently.

The Lancet study involved a total of 46 emergency medical service agencies serving 2 million to 3 million people in the U.S.

Aufderheide said use of the combined devices could save about 8,000 to 10,000 lives a year over standard CPR.

However, it could be another year before the ResQPump is approved for use in the U.S. by the Food and Drug Administration, said Keith Lurie, chief medical officer for Advanced Circulatory Systems of Roseville, Minn., which makes both devices.

He said the company submitted the approval request to the FDA in June and it generally takes a year to 18 months.

In the meantime, communities can do a better job of improving survival by focusing on what already is available, including chest compression, defibrillation and the best care once a person arrives at the hospital, said Michael Sayre, an associate professor of emergency medicine at Ohio State University and spokesman for the American Heart Association.

Sayre noted that survival can vary between 3 percent in some communities to as much as 15 percent.

"There are no magic bullets," he said.

The New England Journal of Medicine study was funded by the National Institutes of Health, the U.S. Army, Canadian health agencies and the Heart Association.

In a related matter, a separate group of researchers said 1,150 deaths from cardiac arrest over a 15-year period were linked to the failure of automated external defibrillators.

Forty-five percent of failures occurred while attempting to charge and deliver the shock to the person in cardiac arrest. Problems with pads, connectors and battery power accounted for the other failures.

The odds of surviving cardiac arrest drop by up to 10 percent for each minute of delay in defibrillation.

"AEDs are like any other piece of medical equipment; they can experience unexpected failures," lead author Lawrence DeLuca, of the University of Arizona Department of Emergency Medicine in Tucson, said in a statement.

The study was published in the Annals of Emergency Medicine.

John Fauber writes for the Milwaukee Journal Sentinel.

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