More Energy Better When Multiple Shocks Required to Restart the Heart

    OTTAWA, March 27 /CNW/ - Results published in the March 27 issue of
Circulation suggest that more energy is better when multiple shocks are
required to restart the heart. The study is the first randomized trial ever to
compare fixed and escalating energy levels in defibrillators used for treating
cardiac arrest outside the hospital.

    "We found that in people who received the escalating shock pattern, 36.6
per cent of shocks resulted in a normal heart rhythm compared to 24.7 per cent
of shocks in those who received the fixed shock pattern," said lead author Dr.
Ian Stiell, a Senior Scientist at the Ottawa Health Research Institute,
Professor and Chair of Emergency Medicine at the University of Ottawa, and
Emergency Department Physician at The Ottawa Hospital. "We hope to repeat this
research in a larger group of patients to determine if the escalating energy
pattern also impacts survival and other outcomes," he added.

    The study included 221 patients in cities across Canada treated by
paramedics or other first responders for cardiac arrest due to ventricular
fibrillation, a condition in which the heart "quivers" rather than pumping
blood to the brain and body. Patients received either 150 joules for all
shocks or 200 joules for the first shock, 300 joules for the second, and 360
joules for remaining shocks as required. First responders were not aware of
the energy levels delivered to individual patients. The study was funded by
Physio-Control, based in Redmond, Wash., a wholly owned subsidiary of
Medtronic, Inc.

    Approximately 40,000 Canadians and 335,000 Americans experience sudden
cardiac arrest each year. The vast majority of these cases occur outside the
hospital, and although survival is less than five per cent, this can be
greatly increased by early CPR and defibrillation.

    "This study demonstrates the enduring commitment held by Physio-Control
to partner with leaders in the field to further scientific understanding of
defibrillation and resuscitation," said Paula Lank, vice president of
regulatory and clinical affairs for Physio-Control. "With a scientifically
rigorous design, this study has demonstrated that the full energy biphasic
capability built into all our defibrillators is beneficial to patients."

    About the Ottawa Health Research Institute

    The Ottawa Health Research Institute (OHRI) is the research arm of The
Ottawa Hospital and an affiliated institute of the University of Ottawa. The
OHRI includes more than 1,200 scientists, clinicians, graduate students,
postdoctoral fellows, and staff conducting research to improve the
understanding, prevention, diagnosis, and treatment of human disease. For more
information visit

For further information:

For further information: Ottawa Health Research Institute Media Contact:
Jennifer Paterson, 613-798-5555 x 19691 Communications and Public Relations

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