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.