The study, conducted at five sites, including Pittsburgh, known as the Assisted Prehospital International Resuscitation Research (ASPIRE) Trial, evaluated the safety and efficacy of AutoPulse
The investigators found the results to be surprising since early clinical trials of the device yielded promising results. Researchers recommend additional research to determine if the device can be used more effectively to treat patients who experience out-of-hospital cardiac arrest.
In the JAMA article, the researchers report that the AutoPulse CPR device did not improve survival rates for patients in out-of-hospital cardiac arrest and in some cases, was associated with worse neurological outcomes in survivors. Because of these findings, the trial was terminated early by the study investigators.
"In the course of conducting emergency medicine research, it is just as important to know what doesn't work as what does when treating patients. While the AutoPulse did not improve survival rates in this trial, we will continue to work alongside EMS services to find methods to combat out-of-hospital cardiac arrest, for which survival rates are extremely low," said Vincent N. Mosesso, M.D., associate professor of emergency medicine at the University of Pittsburgh School of Medicine and principal investigator of the Pittsburgh site.
Out-of-hospital cardiac arrest claims hundreds of thousands of lives each year in the United States. Successful resuscitation depends on a coordinated set of actions including early CPR. Prior studies have shown that rescuers often suffer from what is known as CPR fatigue, making proper performance of manual chest compressions for longer than two minutes difficult.
The multi-center randomized trial included 1,071 patients who experienced out-of-hospital cardiac arrest in the United States and Canada. In the first group, 517 patients received manual CPR while 554 patients received CPR with AutoPulse.
The researchers looked at survival rates four hours after the initial 911 call and at hospital discharge. For those who survived, the researchers looked for signs of cognitive impairment.
There was no significant difference in survival rates four hours after the 911 call between the manual CPR group and the AutoPulse CPR group (29.5 percent vs. 28.5 percent). Survival to hospital discharge was lower in the AutoPulse CPR group (5.8 percent vs. 9.9 percent) as was survival with good cognitive function.
In the Pittsburgh study, 162 patients were enrolled during the two-year trial. However, unlike the overall trial results, survival rates four hours after the 911 call was slightly higher in the AutoPulse CPR group than the manual CPR group (21.6 percent vs. 13.7 percent). Survival to hospital discharge also was higher in the AutoPulse CPR group (6.7 percent vs. 1.9 percent).
"The variance in survival data demonstrates that additional studies are needed to determine the best way to use the AutoPulse device and to treat out-of-hospital cardiac arrest in general," said Dr. Mosesso. "The use of this device is one of several factors to consider when treating out-of-hospital cardiac arrest, including how long someone has been in cardiac arrest, whether or not bystander CPR was performed, the timing of defibrillation and the detriments of delays in starting or interrupting chest compressions."
EMS agencies participating in the Pittsburgh study included Baldwin EMS; Eastern Area Prehospital Services; McKeesport Area Rescue Service; Medical Rescue Team South Authority; Northwest EMS; Ross/Westview EMS; and Tri-Community South EMS.
"While results of the study were not what we expected, the participating EMS agencies did an exceptional job following study protocol and provided the essential data from the field," said James P. Husar, E.M.T.-P., Pittsburgh study coordinator.
This research was conducted under the University of Pittsburgh Institutional Review Board protocol of exemption of informed consent to conduct emergency medicine research. Because obtaining consent for clinical research is impossible at the time of cardiac arrest, the researchers proactively notified both civic leaders and the community that consent would be waived.
Other cities participating in the trial included Calgary, Alberta; Columbus, Ohio; Seattle; and Vancouver, British Columbia. This study was supported by Zoll Corporation.
Last reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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