Chilling the body may help cardiac arrest patients
BY CYNTHIA BILLHARTZ GREGORIAN
Willie H. Taylor was driving his truck on Dec. 4, when he went into cardiac arrest, lost consciousness and careened into a house.
With cardiac arrest, the heart stops beating abruptly for various reasons, depriving the brain and other organs of oxygen.
Most people die or end up in a vegetative state.
But a month later, Taylor, 64, of St. Louis, walked out of St. Louis University Medical Center, good as he was on Dec. 3.
From what he can tell, he owes his recovery in large part to therapeutic hypothermia, a procedure that chilled his body like he'd taken a prolonged dunk in the Arctic Ocean.
"They (doctors) had told my kids that I might be brain dead or not able to walk," Taylor said. "But none of that came true. I got up and walked out of there with all my faculties."
Several area hospitals, including SLU, Barnes-Jewish Hospital and St. John's Mercy Medical Center, perform therapeutic hypothermia on cardiac arrest patients in an effort to prevent brain damage that results from oxygen deprivation.
"Every winter, out in the country, kids fall through the ice, and there's always the one story about the miraculous save and how the kid is rewarmed," said Dr. Michael J. Lim, director of cardiology at St. Louis University. "And even though he was under water for a long period of time with no oxygen, he'd be fine."
Those stories, Lim said, probably spurred the idea for therapeutic hypothermia on cardiac arrest patients.
"One of the reasons they think it works is that the cold water cooled the whole body to a point where damage to organs, especially the brain, didn't happen at the same rate as when the body is at normal temperatures," said Lim. The colder temperatures seem to slow cellular metabolism.
The therapy can be done two ways: by inserting a catheter with cold fluids circulating through it into the heart, or by covering the patient's body with large pads that have cold water circulating through tubes in them.
Taylor underwent the later.
According to Lim, they cool the patients' bodies to 88 or 89 degrees over two or three hours and keep it there for a period of 24 to 36 hours. They also medically induce a coma to prevent shivering.
Once they've determined the underlying cause of the cardiac arrest and feel assured that the heart will beat normally, they discontinue the therapeutic hypothermia, allowing the body to rewarm itself over about three days, though it has taken as long as seven.
The cooling therapy does not increase the chances of surviving cardiac arrest significantly. Instead it increases the chances of those who do survive to avoid severe brain damage.
"The worst case scenario is we find the reason for the cardiac arrest, treat it and stabilize the patient and they don't wake up because they don't get brain function back," Lim said. "But this improves the chance of brain recovery significantly."
A 2002 study by Australian researchers published in "Circulation: Cardiovascular Quality and Outcomes" looked at 77 cardiac arrest patients who were randomly assigned to either get the cooling therapy or not get it. Of the 43 patients who did get the cooling therapy, 21 (or 49 percent) were sent home or to a rehabilitation facility, compared to nine (or 26 percent) of the 34 patients who did not receive the therapy.
Not long after, the American Heart Association recommended that doctors administer hypothermia therapy to patients who experience cardiac arrest that's caused by ventricular fibrillation outside the hospital.
Doctors at Barnes-Jewish also perform the procedure using the catheterization method.
They use a specially designed catheter that's inserted through the femoral vein into the inferior vena cava which carries de-oyxgenated blood to the right atrium of the heart. Blood is cooled as it circulates through the body.
It's active cooling that cools the patient very quickly and precisely, said Dr. Richard G. Bach, director of the cardiac intensive care unit at Barnes-Jewish. And though it's resource-intensive, he and other experts are compelled by data that it's strongly beneficial in a very dismal situation.
"The mortality rate is extremely high (with cardiac arrest), and those who survive or often irreversibly damaged," Bach said. "They're often left in a vegetative state.
This intervention improves their chances at a meaningful life by protecting and preserving brain tissue from lack of oxygen."
Experts are looking at other ways the therapy can be used, for instance in heart attacks, traumatic brain injuries and strokes, Bach said. And they may one day equip ambulances with the technology so the process of cooling patients with no heart beat can start even sooner.
Willie H. Taylor has no idea what caused his cardiac arrest. If doctors told him, he doesn't remember.
"They told me the fire department got there (to the site of the accident) and nothing was working," he said. "My heart wasn't beating, and I didn't have a pulse. They brought me back but my heart stopped again at the hospital."
What he does know is that he was in a coma for 16 days, and that his daughter had recorded his grandchildren's voices on a recorder,
"She played it over and over: 'Wake up, Papa. Wake up, Papa,' and then I woke up," he said. "I felt like I hadn't been through nothing."
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