Scientists Will Test Extreme Hypothermia on Pittsburgh Trauma Patients

Nov. 16, 2011— -- It worked on "Star Trek." Now, researchers are putting a type of suspended animation to the test, investigating whether putting trauma patients into a deep chill might help save their lives.

To test this idea, doctors at the University of Pittsburgh Medical Center will use an experimental technique on Pittsburgh residents who wind up in the trauma center.

The idea is that wounded patients who are bleeding to death can be saved by lowering their body temperature to about 50 degrees. By inducing hypothermia in these patients, doctors hope to buy time to repair their wounds.

Dr. Samuel Tisherman, a critical care specialist at the University of Pittsburgh Medical Center and the lead researcher of the study, said he hopes the procedure also will give trauma patients a chance to survive without extensive brain damage.

"If a patient is losing a lot of blood and the brain doesn't have oxygen, you can start to see damage after about four or five minutes," Tisherman said. "If you can cool the brain down fast enough, you could buy 20 minutes, 40 minutes, maybe up to an hour."

Gunshot or stab wounds often cause so much bleeding that patients' hearts stop beating, bringing them into cardiac arrest. Giving CPR to jumpstart the heart doesn't help because there is not enough blood for the heart to circulate to revive patients.

Operating to repair these wounds is difficult, since the excessive bleeding keeps trauma surgeons from clearly seeing what they're doing. These patients' chances of survival hover at just 7 percent.

Using extreme hypothermia, doctors would try to slow down a patient's bleeding and put the body's blood-dependent systems on ice. The deep-chilling process would begin by injecting an ice-cold solution into trauma patients in cardiac arrest.

After about 15 minutes, the patient should be chilled to about 50 degrees, and surgeons can get to work repairing bleeding tissues, ideally taking no more than an hour to finish. Then patients would be gradually warmed back up again to a normal body temperature.

Tisherman calls the process Emergency Preservation and Resuscitation -- EPR instead of CPR. The project is receiving funding from the Department of Defense.

Using hypothermia to stop bleeding seems counterintuitive, since even mild cooling lowers the blood's ability to clot.

"This approach is 180 degrees opposite to what trauma and emergency physicians normally do," said Dr. Michael West, professor of surgery at the University of California, San Francisco. "However, in this study the heart has already stopped and once the patient is cooled they can safely proceed with identification of bleeding source without cardiac function."

The idea of chilling patients isn't new. Doctors have used hypothermia to treat patients in cardiac arrest since the 1960s. Studies have shown that the technique is highly effective, reducing brain damage by about 50 percent and cutting death rates by 25 percent.

A number of U.S. cities, such as New York, Miami, and Seattle, even require ambulances to take patients in cardiac arrest to hospitals that can induce hypothermia.

But cardiac patients are usually cooled to around 91 degrees, far warmer than the temperatures Tisherman and his colleagues will use.

"The colder you can make someone, the longer you have that they're preserved and you might be able to resuscitate them," Tisherman said. Going any colder than 50 degrees, however, could create more problems.

Tisherman and his colleagues said they have tested this deep-chilling method on pigs and dogs, with considerable success. Now, they'll have to see if it works on human trauma patients. To do that, they'll start trying it out early next year on the residents of Pittsburgh who come to the hospital with traumatic injuries, a fact that raises a number of thorny ethical issues.

Patients who are bleeding to death are in no state to give the informed consent usually required in clinical trials that test new treatments. There isn't even time to get the consent from a family member. But new treatments designed for patients in such a state can never be used if they aren't tested first.

"The only way you learn about promising techniques and whether they will work or not is by trying them out," said Rosamond Rhodes, director of bioethics education at the Mount Sinai School of Medicine.

Rhodes said government regulators say new treatments can be tested without informed consent if studies meet three requirements: the condition being treated is life-threatening, the patient would benefit considerably from treatment, and getting the patient's informed consent is impossible. The extreme hypothermia study meets those criteria, Rhodes said.

On Tuesday, Tisherman and his colleagues started a campaign to educate Pittsburgh residents about the deep-chilling process. The University of Pittsburgh put ads on city buses, created a website, and posted a video on YouTube, giving residents more information about the treatment. They will also hold town hall meetings in early December, where patients who are concerned about the risks of the procedure can opt out.

Children, pregnant women, and people over age 65 who wind up in the trauma unit will be automatically ineligible for deep chilling. So will patients who have blunt trauma from falls or car accidents. But other residents who want to opt out will be given a bracelet to wear as an indication to trauma nurses and doctors not to start the chilling process.

Tisherman said the University of Pittsburgh trauma team will use deep-chilling procedure on only about 10 patients initially.

If the treatment works, emergency physicians say it will be a big step forward in treating trauma patients.

"If you have massive trauma and cardiac arrest, your chances of survival are extremely low," said Dr. Arie Blitz, director of cardiac transplant surgery at University Hospitals in Cleveland. "Any efforts to improve these outcomes would be a great contribution to both civilian and wartime traumatic scenarios."

Dr. Art Caplan, a bioethicist at the University of Pennsylvania, said the new procedure is promising and should be tested, but it raises a number of inescapable ethical issues, including the possibility of neurological damage.

"Yes, we saved their life, but you could leave some damaged, some severely disabled," Caplan said. "Who's going to pay the cost of caring for such people?"

Blitz noted that any patient who goes into cardiac arrest runs the risk of winding up with brain damage.

"You have to remember the situation. These trauma patients have a 93 percent chance of dying. Despite all the advances in trauma care, we've never been able to improve that," Blitz said. "I think the risks are very worth it."