(August 2010) When you ask Jennifer Colella what it was like to be put in a coma with her body cooled to 33 degrees, she draws a blank. She knows that what she thought was a stomach bug had turned into relentless vomiting, and pain in her rib cage and stomach had caused her to roll up like a ball on the floor. She was flown to Yale-New Haven Hospital in a Life Star helicopter. Then it was as if a thick fog was settling around her, and she called for her children.
Tests showed that her liver was failing. Only a transplant could cure her, but there were no organs available. The clock was ticking. To protect her brain from dangerous swelling, doctors proceeded with therapeutic hypothermia, literally putting her “on ice” for 48 hours while they waited for a donor.
After that, “I was very sick and don’t remember anything else,” she says.
A medical team uses the Arctic Sun Temperature Management System to cool a heart attack patient in a Yale-New Haven Hospital emergency room.
She was still cold when an organ became available for transplant. Colella now holds the distinction of being one of 30 patients Yale Medical Group doctors saved last year with the help of therapeutic hypothermia.
Charles Wira, MD, introduced the technique in Yale-New Haven Hospital’s emergency room, where it is considered routine for selected heart patients. Interventional cardiologist Jeptha Curtis, MD, helped develop the approach at Yale.
The American Heart Association (AHA) issued recommendations for cooling cardiac arrest patients for up to 24 hours as far back as 2005. However, critical care physician Peter Marshall, MD, says only about 10 percent of hospitals offer it even though it is proven effective, more patients recover function than in the past and spend less time in the hospital.
While some hospitals use water blankets, wraps or ice packs, Marshall and his colleagues use the noninvasive Arctic Sun Temperature Management System, which involves putting gel pads on the patient's body to monitor and maintain core temperature in a therapeutic range—between 32 degrees and 38.5 degrees Celsius—manage the temperature more efficiently and provide greater skin protection.
When there is no other solution, Marshall and his colleagues have challenged the AHA's recommended age barriers and saved the lives of patients in their 80s with heart failure and prior strokes, and a 16-year-old boy with congenital arrhythmia. They’ll consider the technique for some pregnant women with input from high risk obstetricians and neonatologists.
While therapeutic hypothermia has become routine for some cardiac patients, Peter Marshall, MD, uses it on liver transplant and stroke patients as well.
For liver patients, the success rate is not as high. However, medical literature is accumulating to suggest the technique can reduce damage and save lives for some liver patients, as well as for patients in the intensive care unit (ICU) suffering from such conditions as ischemic stroke and brain hemorrhages.
“These patients may be cooled for many, many days,” says Marshall. But,“typically the average time in ICU is 48-72 hours before you know they are going to recover.”
Transplant hepatologist Michael L. Schilsky, MD, has used the technique successfully on just a few liver patients to prevent swelling of the brain caused by acute liver failure. “You’re in a battle between recovery of the liver and sustaining that person in a good state without further brain injury until you can transplant them,” he says. “We warm these patients only after recovery or transplant, and we do that at a slow rate so we don’t cause any tissue damage.”
Marshall, right, discusses therapeutic hypothermia cases with cardiologist Joseph Akar in the emergency room. He says teamwork is critical.
It’s critical to have a specially trained “chill team,” with other specialists and nurses monitoring patients continually.
“There could very well be complications,” Marshall says. “There can be problems with magnesium levels, potassium levels, skin complications and kidney injury. It can lower blood pressure, and result in poor clotting. That’s why you have cardiologists to deal with the heart, a neurologist to deal with the brain, and a medical intensivist to deal with all of the other problems.”
It’s important to make sure families know what to expect. “Their loved one is pretty much going to be going into a black box for 24 hours. They will be cooled and put on a ventilator. They may even need to be paralyzed intentionally, because shivering is something that the body does naturally when it gets cold, and shivering speeds up the brain, which is bad for neurological recovery. They’re not going to be able to communicate with their relative, and there is not much we’ll be able to tell about how they’re doing until they come out the other side of it.”
Colella remembers coming out of hypothermia feeling disoriented for about a week. Months later she feels fortunate. She isn’t ready to go back to strenuous activities, but she says she knows that she’s going to be OK.
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When a heart attack patient arrives in the Yale-New Haven Hospital emergency room, the wheels turn quickly. Usually paramedics will call ahead to say their patient may be a candidate for hypothermia because he or she has edema, is not waking up, and is on a breathing machine or defibrillator.
If a hospital cardiologist agrees, a call goes out to one of five core critical care physicians on call 24/7. They are Peter Marshall, MD; Danielle Antin-Ozerkis, MD; Shyoko Honiden, MD; John Raymond McArdle, MD; Mark David Siegel, MD; and Jonathan Siner, MD.
“The doctor on call will give the patient cold saline to start the process—you have four hours to start the process once they get back circulation,” says Marshall. “Then it’s important to keep the temperature to the goal temperature, and not to have fluctuations. We keep them at the goal temperature for 24 hours. Then we warm them up for 24 hours, because warming up too rapidly is also dangerous.”
Cardiologists can take the patient to the catheterization laboratory while they are cold. “Our process doesn’t delay that,” Marshall says.
“There are still unanswered questions about the process,” he says. But for heart attacks, the numbers are impressive: 67 to 71 percent of patients who have an out-of-hospital cardiac arrest die in the hospital, usually of a brain injury; therapeutic hypothermia cuts that death rate by a third.