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Study of Mechanical Chest Compression Device Ends

Notice of public disclosure for emergency medicine research

DALLAS, November 12, 2005 — A multi-center study testing and comparing the effectiveness of a mechanical chest compression device versus manual chest compressions for out-of-hospital sudden cardiac arrest has been terminated after analysis of preliminary data suggested that some patients treated with the mechanical device may fare worse than those receiving manual chest compressions. Results of this study are being presented today at the American Heart Association Resuscitation Science Symposium in Dallas.

The study, called the AutoPulse™ Assisted Prehospital International Resuscitation Trial (ASPIRE), was coordinated by the University of Washington, with participating centers at the University of Calgary, University of British Columbia, Ohio State University and the University of Pittsburgh School of Medicine.

The 111 eligible patients who were enrolled in the Pittsburgh region, however, fared better with the mechanical chest compressions versus manual chest compressions.

Beginning in September 2004, emergency medical service personnel performed either manual cardiopulmonary resuscitation (CPR) or used the FDA-approved AutoPulse CPR assist device to deliver chest compressions to adults during cardiac arrest outside of hospital settings. Patients had a 50/50 chance of being treated with manual CPR or the AutoPulse. The study had planned to enroll 1800 patients and monitor the survival of both patient groups for four hours, starting from the time of the 9-1-1 call. Patients who survived to be discharged from the hospital were followed for three months.

However, an independent data board that monitored the overall safety and efficacy of the study recommended suspending patient enrollment in all sites after a preliminary analysis of outcomes suggested a potential negative effect in the patients treated with the AutoPulse. After further analysis of the 1,071 enrolled subjects, the ASPIRE investigators terminated the study early.

Overall, the study analysis showed minimal difference between the two groups of patients and their four-hour survival rates following the 9-1-1 call; after four hours, 24.7 percent of patients treated with manual CPR survived while 26.4 percent of patients treated with AutoPulse CPR survived. However, 9.9 percent of the manual CPR patients survived to hospital discharge compared to 5.9 percent of the AutoPulse-treated patients.

Pittsburgh patients, however, fared better. After four hours, 13.7 percent of patients treated with manual CPR survived for four hours following the 9-1-1 call while 21.6 percent of patients treated with AutoPulse survived. Of the Pittsburgh enrollees, 1.9 percent of the manual CPR patients survived to hospital discharge compared to 6.7 percent of the AutoPulse-treated patients.

Thus far, investigators have been unable to determine the reason for these outcomes, but AutoPulse maker ZOLL Circulation, which sponsored the study, continues to evaluate the data for possible explanation.

“The overall results of this first multi-center study of the AutoPulse device were unexpected and disappointing. However, we remain optimistic that with further modifications of the device and how it is used, it may prove to be an effective treatment for sudden cardiac arrest, which is a leading cause of death in the United States with a mortality rate of more than 90 percent,” said Vincent N. Mosesso, M.D., associate professor of emergency medicine at the University of Pittsburgh, medical director of UPMC Prehospital Care and principal investigator of the Pittsburgh study site.

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