The brain-preserving cooling treatment known as therapeutic hypothermia is rarely being used in patients who suffer cardiac arrest while in the hospital, despite its proven potential to improve survival and neurological function, researchers says.

The researchers, from thePerelman School of Medicineat the University of Pennsylvania in Philadelphia, reported their findings in the June issue ofCritical Care Medicine.

The authors suggest that scarce data about in-hospital cardiac arrest patients and guidelines that only call for health care providers to consider use of therapeutic hypothermia, rather than explicitly recommending it, may explain the study's results.

In a prospective study between 2003 and 2009 of more than 530 hospitals in the United States, the Penn team found that 98 percent of more than 67,000 patients who went into cardiac arrest in the hospital received only conventional post-resuscitation care. That left just 2 percent who received therapeutic hypothermia, which has been credited with saving the lives of a growing number of patients who arrest outside hospitals.

"We know it's being used in patients who went into cardiac arrest in their homes, at work, or anywhere else outside of a hospital, but little was known about how often it's used in patients who arrest in the hospital," says Dr. Mark E. Mikkelsen, assistant professor in the division of pulmonology, critical care, and allergy at Penn Medicine. "We found that even though most hospitals have the capability to treat these patients with therapeutic hypothermia, it's not being used. And even when it was used, in nearly half the cases, the correct target temperature was not being achieved."

He adds, "Several factors could explain this: There is little data, which is often conflicting, to support its use for patients in the hospital, and we have national guidelines that only have clinicians considering its use, which may lead to hesitation and lack of institutional protocol."

Cooling the body down to about 89.6 degrees after cardiac arrest protects it against neurological damage initiated by the lack of blood flow and oxygenation, several studies of out-of-hospital cardiac arrest patients have shown. It has also been shown to improve survival—a welcome development, since cardiac arrest survival statistics remain grim, with less than 10 percent of patients surviving in most cities across the U.S.

More than 300,000 people who go into cardiac arrest out of the hospital die each year nationally; thousands of others are left neurologically devastated.

About 210,000 patients a year go into cardiac arrest while in the hospital—many of those patients may have other conditions that point to a poor prognosis, and a substantial portion may be terminally ill patients who are not candidates for hypothermia.

National recommendations established in 2005 call for out-of-hospital cardiac arrest patients to be treated with hypothermia when they remain comatose after resuscitation. In-hospital recommendations, however, are less direct.

The International Liaison Committee on Resuscitation guidelines suggest providers "consider its use," while the American Heart Association says therapeutic hypothermia "may be considered" for a patient who goes into cardiac arrest caused by non-shockable rhythms.

For the study, the team analyzed treatments of about 67,500 patients at 538 hospitals participating in the American Heart Association's Get With the Guidelines-Resuscitation database from 2003 to 2009. Of those patients, 1,367 patients were given therapeutic hypothermia. The use of therapeutic hypothermia increased slightly, from 0.7 percent in 2003 to 3.3 percent in 2009.

Younger patients and patients who were treated in a non-ICU location and a teaching hospital were more likely to get therapeutic hypothermia.

Even when it was used, however, target temperature (89.6 degrees to 93.2 degrees Fahrenheit ) was not achieved in 44.3 percent of the patients within 24 hours, and 17.6 percent were overcooled.

"These rates are particularly important to examine, given that the incidence of in hospital events appears to be increasing," Mikkelsen says. "I believe there is potential for therapeutic hypothermia to benefit this population, but traction can only be made after clinical trials investigating safety and effectiveness are initiated, which are certainly warranted. Results of those studies could strengthen the case for stronger recommendations and increase use."

The Perelman School of Medicine has been ranked among the top five medical schools in the U.S. for the past 16 years in the U.S. News & World Report's survey of research-oriented medical schools.

The school is consistently among the nation's top recipients of funding from the National Institutes of Health, with $398 million awarded in the 2012 fiscal year.

The University of Pennsylvania Health System's patient care facilities include: The Hospital of the University of Pennsylvania, Penn Presbyterian Medical Center, and Pennsylvania Hospital, which is considered the nation's first hospital, founded in 1751. Penn Medicine also includes additional patient care facilities and services throughout the Philadelphia region.