Regional System to Cool, Warm Cardiac Arrest Patients Saves Brain Function
‘… if you have a cardiac arrest 200 miles away or on our doorstep, the quality of the outcomes is identical’ - What is
cardiac arrest? - see below news story
July 12, 2011 - A broad, regional system to lower the temperature of resuscitated cardiac arrest patients at a
centrally-located hospital improved outcomes, according to a study in Circulation: Journal of the American Heart Association. Cooling
treatment, or therapeutic hypothermia, is effective yet underused, researchers said.
A network of first responders, EMS departments and more than 30 independent hospitals within 200 miles of Minneapolis,
Minn., and Abbott Northwestern Hospital collaborated to implement the protocol.
“We’ve shown that a fully integrated system of care, from EMS through hospital discharge, can provide this essential
therapy to victims of out-of-hospital cardiac arrest across a broad geographic region,” said Michael Mooney, M.D., the study’s lead author and
director of the therapeutic hypothermia program at Minneapolis Heart Institute, where the protocol was developed.
Researchers tracked 140 patients who suffered out-of-hospital cardiac arrest between February 2006 and August 2009.
Although their heartbeat and circulation were restored within an hour of collapse, they remained unresponsive.
Ice packs were used to begin the cooling process, which started during initial EMS transport to the hospital and in the
emergency departments of the network hospitals. One hundred forty patients were admitted to Abbott Northwestern Hospitals for therapeutic
hypothermia and re-warming — 107 of those were transferred from other hospitals.
Over three to four hours, the patients’ core body temperature was lowered to about 92 degrees Fahrenheit and maintained
at that temperature for about 24 hours. Over the next eight hours, physicians gradually re-warmed them to a normal temperature.
Researchers found that:
>> Among the 56 percent of patients who survived to hospital discharge, 92 percent had positive neurological
scores, indicating no severe disability. Prior to the protocol, about 77 percent of similar patients had positive neurologic scores.
>> The risk of death rose 20 percent for each hour of delay between the return of spontaneous circulation and
>> Survival rates were comparable between patients who were transferred for care within the network and those who
“What our data show is if you have a cardiac arrest 200 miles away or on our doorstep, the quality of the outcomes is
identical,” Mooney said.
About 300,000 out-of-hospital cardiac arrests occur in the United States each year and most are fatal, according to the
American Heart Association.
If a cardiac arrest patient survives the initial loss of oxygen from their arrest, they then face the destruction that
unfolds after their blood flow is rapidly restored, which is devastating and often fatal.
Therapeutic hypothermia blunts the damage that can occur in the 16-hour window after bloodflow is restored. The American
Heart Association and other experts recommend therapeutic hypothermia, but U.S. cardiologists have been slow to use it.
The efficiencies of the area’s existing network, transfer agreements and working relationships between the EMS
departments, network hospitals and the central hospital helped Mooney and his colleagues implement the protocol.
About half of all patients received therapeutic hypothermia while also being treated for a severe form of heart attack
(ST-elevation myocardial infarction) in the catheterization lab, said Barbara Unger, R.N., co-author of the study and director of
cardiovascular emergency program development for the Minneapolis Heart Institute.
The average age of patients in the study was 62 and 77 percent were men. Older patients fared slightly worse
neurologically, the study found.
Co-authors are: Lori L. Boland, M.P.H.; M. Nicholas Burke, M.D.; Kalie Y. Kebed, B.S.; Kevin J. Graham, M.D.; Timothy D.
Henry, M.D.; William T. Katsiyiannis, M.D.; Paul A. Satterlee, M.D.; Sue Sendelbach, Ph.D., R.N., C.C.N.S.; James S. Hodges, Ph.D.; and
William M. Parham, M.D. Author disclosures are on the manuscript.
The Minneapolis Heart Institute Foundation funded the study.
What is cardiac arrest?
Cardiac arrest is the abrupt loss of heart function in a person who may or may not have diagnosed heart disease. The time and mode of death
are unexpected. It occurs instantly or shortly after symptoms appear.
Each year about 295,000 emergency medical services-treated out-of-hospital cardiac arrests occur in the United States.
Is a heart attack the same as cardiac arrest?
No. The term "heart attack" is often mistakenly used to describe sudden cardiac arrest. While a heart attack may cause cardiac arrest and
sudden death, the terms don't mean the same thing.
Heart attacks are caused by a blockage that stops blood flow to the heart. A heart attack
(or myocardial infarction) refers to death of heart muscle tissue due to the loss of blood supply, not necessarily resulting in the death of
the heart attack victim.
Cardiac arrest is caused when the heart's electrical system malfunctions. In cardiac arrest death results when the heart suddenly stops
working properly. This is caused by abnormal, or irregular, heart rhythms (called
The most common arrhythmia in cardiac arrest is
ventricular fibrillation. This is when the heart's lower chambers suddenly start beating chaotically and don't pump blood. Death occurs
within minutes after the heart stops.
Cardiac arrest may be reversed if CPR (cardiopulmonary resuscitation) is performed and a defibrillator
is used to shock the heart and restore a normal heart rhythm within a few minutes.