Friday, September 7, 2007

New CPR Technique Advocated: An Abdominal Approach

Filed under: Anesthesiology , Critical Care , Emergency Medicine , Medicine

A new method of administering cardiopulmonary resuscitation is being proposed by a Purdue professor of biomedicine. The new technique focuses on applying pressure to the abdomen rather than the chest, and according to the research, the study "provided 25 percent more blood flow through the heart muscle without retrograde flow in the coronary arteries," all while reducing the chances of damage to the rib cage.

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 [Leslie Geddes, the Showalter Distinguished Professor Emeritus in Purdue's Weldon School of Biomedical Engineering --ed].

"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.

Purdue Press Release: New CPR promises better results by compressing abdomen, not chest...

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