The device, which resembles an eight-inch wide seat belt, is buckled around the chest, tightened and motorized. Once switched on, it contracts against the chest, stimulating blood flow.
Researchers who tested the device on 20 pigs in cardiac arrest found that it restored blood flow four times better than manual compressions and returned the hearts to pre-arrest condition. Results of the study, supported by Revivant Corp., are to be presented Nov. 19 at the American Heart Association's 75th annual Scientific Sessions in Chicago.
"The key to restoring viability is to wash out the waste and move oxygenated blood to the vital organs," says Henry R. Halperin, M.D., lead author of the study and professor of medicine and biomedical engineering at Hopkins. "The belt can compress a greater area of the chest than manual compressions, so it restores more blood flow than manual CPR. Wherever a health care professional would do manual CPR, a device like this could be better for the patient."
Researchers induced ventricular fibrillation, an electrical abnormality in the heart that precedes cardiac arrest, in the pigs. They then performed both manual cardiopulmonary resuscitation and CPR using the belt device, in random order, and measured blood pressure and flow before and after injecting the pigs with epinephrine, a hormone that constricts small blood vessels.
About 350,000 people each year suffer sudden cardiac arrest, 95 percent of whom die; most require defibrillation. Defibrillators are most effective if used within the first two minutes of arrest, Halperin says, but most attacks occur at home. It can take an average of six to eight minutes for paramedics to arrive, he says, and defibrillation is often unsuccessful at that time. At that point, generating more blood flow is the key to survival.
The device tested was Revivant's Autopulse. The study group is planning a clinical trial to evaluate the device's performance on humans. Other authors were Menekhem Zviman and Jennifer Johnson of Hopkins; Norman Paradis of the University of Colorado Health Science Center; Joseph P. Ornato of Virginia Commonwealth University Health System; and Karl B. Kern of the University of Arizona.
Halperin is a paid consultant of Revivant, holds stock in the company and is a member of the organization's scientific advisory board. These relationships are managed by The Johns Hopkins University in accordance with its conflict-of-interest policies.
Abstract #115668: Halperin, H.R. et al, "Improved Hemodynamics with a Novel Chest Compression Device in a Porcine Model of Cardiac Arrest"
Photos available at: http://www.hopkinsmedicine.org/press/2002/November/021114_AHA.htm
Related Web sites:
Johns Hopkins - Division of Cardiology http://www.hopkinsmedicine.org/cardiology/index.htm
American Heart Association http://www.americanheart.org
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