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Community Study on Victims of Cardiac Arrest Completed

Study examined treatments by paramedics and EMTs at the scene of a person's collapse

Giving cardiac arrest patients at least 30 seconds of CPR before assessing the need to use an electrical shock to restart their hearts is just as effective as performing 3 minutes of CPR before the assessment, a recently completed study found.

The study, known as the Resuscitation Outcomes Consortium Prehospital Resuscitation using an IMpedance valve and Early versus Delayed analysis (ROC PRIMED), looked at the amount of time CPR is administered before assessing whether an electrical shock is required to restart the heart of someone with cardiac arrest outside the hospital. Smaller studies have shown that a sustained amount of CPR before shocking the heart may lead to increased blood flow and improved outcomes. In the past, the standard treatment had been to immediately shock the heart.

"We went into this study knowing that CPR before defibrillation was important but not how much CPR was needed," said Mohamud Daya, M.D., lead investigator of the study and Associate Professor of Emergency Medicine in the Oregon Health & Science University School of Medicine. "The study looked at least 30 seconds of CPR versus 3 minutes of CPR and the preliminary study data showed that both strategies were equally effective."

This study also examined the benefits of using an impedance threshold device (ITD) to resuscitate cardiac arrest patients. This small, plastic device, about the size of a fist, fits onto the facemask or breathing tube used during CPR. Subjects eligible for the ITD part of the study randomly received either standard CPR with the actual device or CPR with a device that looks identical to the ITD, but does nothing. Neither the paramedics nor the study investigators knew which device patients received.  Researchers believed the ITD might provide increased blood flow back to the heart during the chest release phase of CPR, allowing more blood to circulate during the chest compression phase.  The preliminary results indicate similar survival rates between both groups of patients, suggesting that standard CPR is as effective as CPR with an ITD. These findings are important for decision makers responsible for making informed choices about health care resource utilization in the EMS setting.

Cardiovascular disease is the most common cause of death in the United States and Canada. More than 350,000 people die every year from cardiac arrest in North America. About half of these people have shown no prior symptoms of heart disease, and only 5-10 percent will survive. "Overall survival in this study was higher than expected even though the study did not find that any of the interventions tested was better than another" said Dr. Terri Schmidt, one of the study investigators.

"Sudden cardiac arrest remains a major public health problem in the United States," Daya said. "It's important we continue to rigorously investigate methods for saving the lives of cardiac arrest patients. We have contributed to the science underlying cardiac resuscitation in an important and very meaningful way by participating in one of the largest randomized controlled trials ever conducted in the pre-hospital setting."

The ROC PRIMED study excluded anyone with a known preference for refusing lifesaving treatment, as stated on a Physicians Orders for Life Sustaining Treatment (POLST) form or other advance directives, women with an obvious pregnancy or people under arrest at the time of the cardiac arrest. The study only enrolled people ages 18 and older.

The ROC PRIMED study is one of a series of federally funded studies known as the Resuscitation Outcomes Consortium (ROC). Portland was designated a ROC community by the National Institutes of Health in 2004. The consortium comprises 10 regional medical centers across the United States and Canada that seek to find promising scientific and clinical advances to improve survival from cardiac arrest and severe trauma. These studies enroll patients in the emergency setting without their consent under the FDA's exception from informed consent rules.  Before each study was initiated, there was an extended period of public notification and consultation.  Community members were also provided with a way to "opt-out" of studies like this one, by requesting and wearing a "no study" bracelet (similar to medical alert bracelet) that EMS providers were trained to look for and honor.

EMS agencies across North America use slightly varying methods to treat patients. ROC investigators would like to determine the best methods for treating victims of cardiac arrest and severe trauma. The best way to do this is to get the treatment to victims as quickly as possible, which means at the site of the incident. The ROC consortium allows studies to be conducted simultaneously in multiple locations, both urban and rural, thus taking less time to complete, and allowing results to more quickly guide future practice.

The National Heart and Lung Blood Institute is the lead federal sponsor of the ROC studies. Additional funding is provided by the NIH's National Institute of Neurological Disorders and Stroke, the Institute of Circulatory and Respiratory Health of the Canadian Institutes of Health Research, US Army Medical Research & Materiel Command, American Heart Association, Defense Research and Development Canada, and the Heart and Stroke Foundation of Canada. For more information about the ROC PRIMED study or other studies within the Department of Emergency Medicine at OHSU, the community can visit

About OHSU

Oregon Health & Science University is the state's only health and research university, and Oregon's only academic health center. OHSU is Portland's largest employer and the fourth largest in Oregon (excluding government). OHSU's size contributes to its ability to provide many services and community support activities not found anywhere else in the state. It serves patients from every corner of the state, and is a conduit for learning for more than 3,400 students and trainees. OHSU is the source of more than 200 community outreach programs that bring health and education services to every county in the state.

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