The Big Chill Works

The American Heart Association estimates 265,100 EMS-treated out-of-hospital cardiac arrests occur annually in the U.S.
According to Dr. Raj H. Chandwaney, an intervention cardiologist at the Oklahoman Heart Institute, survival rates range from 1 to 5 percent, only 40 percent of which have good neurologic recovery.
“Brain injury among survivors is a good indicator the patient will die in the six months after discharge,” Chandwaney said.
Determined to improve that prognosis, OHI, EMSA and other area hospitals are implementing a medical protocol to induce hypothermia in comatose survivors, a procedure that more than doubles the chances of meaningful recovery.
The protocol, adapted from one that has been in place at the University of Chicago for several years, instructs physicians to cool qualifying patients to a temperature of 32 degrees Celsius for 24 hours using both intravenous cooling technique (chilled saline) with surface cooling.
“Researchers are uncertain why it works,” Chandwaney said.
There are two probable reasons. Cardiac arrest deprives the brain of oxygen, causing damage. Every 1 C drop in temperature reduces cerebral metabolic rate for oxygen 6 percent.
Lower temperatures may also suppress chemical reactions associated with restoration of blood flow to the brain, such as free radical production, excitatory amino acid release, calcium shifts, mitochondrial damage and apoptosis.
While there isn’t full understanding of why the protocol works, there is plenty of evidence that it does, Chandwaney said.
“Whatever the mechanism is, there are fewer body bags, and that is what is important,” Chandwaney said.
The protocol is so successful, in fact, it is becoming standard of care. The International Liaison Committee On Resuscitation, a panel of experts, published a statement supporting the practice in 2003, and the American Heart Association recommends it.
According to the New York Times, cardiac arrest patients in New York will even be diverted from hospitals that do not have protocols in place.
While its effectiveness is widely accepted, only 25 percent of the hospitals in the United States, and only one in Tulsa, have actually implemented hypothermia protocols.
Chandwaney said some resistance to the procedure stems from the difficulty of early incarnations of induced hypothermia, which involved attendants covering patients with bags of ice.
The ultra low-tech technique, while extremely cheap, presented a slew of problems: The danger of overshooting target temperatures was high due to lack of control, and condensation on the bags created slick floors and the danger of electrocution if defibrillation was needed.
The solution is a device — OHI uses the Gaymar Medi-Therm Hyper/Hypothermia System equipped with Rapr-Round Body Wraps — that uses surface cooling pads and automated monitoring to control body temperature. According to Gaymar, the machine costs under $6,000 in the United States, and the replacement cooling pads cost below $200 per patient. OHI has five machines.
OHI, part of the Hillcrest Medical System, is the only Tulsa hospital that has adopted this protocol, though Saint Francis said it plans to have a protocol in place by the new year, if not sooner. St. John did not respond to calls.
EMTs are buying in as well.
TJ Reginald, Director of Clinical Research and Development, Office of the Medical Director at EMSA, said the service will adopt a protocol to initiate cooling using chilled saline by Jan. 2010, though there are still issues to work out.
EMSA’s largest expense will be the purchase of mobile refrigeration equipment capable of maintaining a fluid temperature of 4 C, which will cost roughly $1,000 per ambulance.
“Some new ambulances will have the refrigeration equipment on them,” he said. “The rest of the older fleet will probably carry a specialized cooling case to accomplish this task.”
Regardless of the difficulty implementing a new protocol, Chandwaney said he believes the procedure will become standard at Tulsa hospitals.
“Hypothermia is a simple therapy that has been proven to improve survival in a patient population that normally has a very poor prognosis,” he said. “I hope to see it become standard of care at all hospitals.” ?



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