More effective method needed

A new way to perform cardiopulmonary resuscitation that promises to be more effective than standard CPR because it increases nourishing blood flow through the heart by 25% over the current method has been developed by a biomedical engineer at Purdue University, West Lafayette, Ind.

The technique is needed desperately because conventional CPR has a success rate of five to 10%, depending on how fast rescuers are able to respond and how well the procedure is performed. For every one minute of delay, the resuscitation rate decreases by 10%. "In other words, at 10 minutes, the resuscitation is absolutely ineffective," points out Leslie Geddes, professor emeritus in the Weldon School of Biomedical Engineering.

"Any medical procedure that had that low a success rate would be abandoned right away, but the alternative is not very good, either: Don't do CPR and the person is going to die." Geddes has developed a CPR alternative, called "only rhythmic abdominal compression," or OAC-CPR, which works by pushing on the abdomen instead of the chest.

"There are major problems with standard CPR," Geddes explains. "One is the risk of breaking ribs if you push too hard but, if you don't push hard, you won't save the person. Another problem is the risk of transferring infection with mouth-to-mouth breathing." The new CPR method eliminates both risks.

In standard chest-compression CPR, which has been in practice since the 1960s, the rescuer pushes on the chest and blows into the subject's mouth twice for every 30 chest compressions. However, the risk of infection is so great that many doctors and nurses often refuse to give mouth-to-mouth resuscitation. In one study, 45% of physicians and 80% of nurses said they would refuse to administer mouth-to-mouth resuscitation on a stranger. "This is the real world that nobody knows about, and it's a sobering thought," Geddes states. It is not necessary to perform mouth-to-mouth resuscitation with OAC-CPR.

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The American Heart Association requires that rescuers administering CPR push with enough force to depress the chest 1 1/2 to two inches at a rate of 100 times per minute. "[That] takes 100 to 125 pounds of force," Geddes confirms. "So, you have to push pretty hard and pretty fast, and two people are needed to perform it properly. One blows up the lungs and the other compresses the chest and, when the one who's compressing the chest gets tired, they change positions."

OAC-CPR requires only one rescuer. Instead of two breaths for every 30 chest compressions, the 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 reports. "She made the remarkable observation that, if you pushed on the abdomen after each chest compression, you could double the CPR blood flow. 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 perform "coronary perfusion," or pumping blood through the heart muscle effectively, which is critical for successful resuscitation because the heart muscle is nourished by oxygenated blood. "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 concludes. "This retrograde flow reduces the likelihood of resuscitation."

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