Too Much Oxygen May Be Harmful, Not Helpful Following Cardiac Arrest, Cooper Researchers Find

Pivotal Study to be Published in Leading Medical Journal

Compelling new evidence demonstrates that too much oxygen following cardiac arrest may be harmful, not helpful to patients according to researchers at Cooper University Health Care and Cooper Medical School of Rowan University. The results of their multi-center study on this topic, which was funded by a grant from the National Institutes of Health (NIH), will be published in Circulation, the journal of the American Heart Association.

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“Our research set out to answer the often debated question about the optimal level of oxygen concentration for patients once they have been resuscitated from cardiac arrest,” explained Stephen Trzeciak, MD, MPH, the Principal Investigator of the research and Professor of Medicine at Cooper. “There have been conflicting results with historical studies, but our latest research results support the hypothesis that too much oxygen after the patient has been revived can intensify brain damage in these situations.”

“When a patient experiences cardiac arrest, the brain cells are deprived of oxygen, and this can result in permanent brain damage,” said Hope Kilgannon, MD, Emergency Medicine specialist at Cooper, Associate Professor of Emergency Medicine, and co-author of the study. “The brain damage may actually be intensified if too much oxygen is given once blood flow is restored.”

Conventionally, patients are administered 100 percent oxygen during cardiac arrest and resuscitation in attempts to get the heart restarted. However, after the heart is successfully restarted, the optimal level of oxygen that the patient needs has been a source of controversy among physicians.

Cooper’s researchers have been studying this issue for a number of years as part of the NIH-funded research grant. In 2010, the Journal of the American Medical Association (JAMA) published the research team’s results of the first large-scale report of outcomes in humans. The initial study included information from a critical care database of patients at 120 U.S. hospitals, and showed that patients with exposure to excessively high oxygen levels in the blood – a condition referred to as hyperoxia – had the highest mortality rate of all subjects in the study, even compared to those with persistently low oxygen levels.

Cooper University Hospital was the coordinating center for the newest study, conducted in collaboration with Indiana University School of Medicine; University of Mississippi Medical Center; Beth Israel Deaconess Medical Center in Boston; Penn-Presbyterian Medical Center in Philadelphia; and the Hospital of the University of Pennsylvania.

Of 280 adult patients resuscitated from cardiac arrest at these six hospitals across the United States, 105 (38 percent) had exposure to hyperoxia. Seventy percent of the 280 patients died in the hospital or survived to hospital discharge with severe brain injury.  Patients with exposure to hyperoxia were more likely to die or survive with severe brain injury (77 percent vs. 65 percent among patients with and without exposure to hyperoxia respectively).  Additionally, further analysis showed that on average for every one-hour longer duration of hyperoxia exposure there was an additional 3 percent increase in patients’ risk of death or severe brain injury.

“While intuitively it may seem that more oxygen is better, the conclusions of this study support our hypothesis that excessively high oxygen levels after resuscitation from cardiac arrest may actually cause further harm to patients,” said Dr. Trzeciak.  “The next step in this line of research is a clinical trial to determine the best method of reducing supplemental oxygen and preventing hyperoxia exposure, to improve outcomes for victims of cardiac arrest.”



Wendy A. Marano, Public Relations Manager
Cooper University Health Care

Sharon R. Clark, Director, Marketing and PR
Cooper Medical School of Rowan University
Office: 856.361.2825

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