Vanderbilt LifeFlight moves a cardiac patient from the chopper into the Emergency Department. Photo by Wayne Cowan.
Emergency Responders Launch Protocol in the field
Therapeutic hypothermia to ward off brain damage after sudden heart stoppage is today accepted protocol in Nashville’s major hospitals, as well as among many emergency management responders.
“I see an increased use in the sense that we have protocols and pathways in place that make it easier to launch the hypothermia protocol. People feel comfortable with it, and we’re utilizing it,” said P. Robert Myers, MD, PhD, a cardiologist with Centennial Heart.
Early last decade, the American medical community began warming to the idea of cooling cardiac-arrest patients; and in February 2002, the New England Journal of Medicine published research extolling therapeutic hypothermia’s value. By 2008, cardiologists and emergency room physicians in Nashville hospitals were establishing and instituting protocols to ensure the therapy’s smooth and consistent use when appropriate.
The protocol involves lowering the patient’s body temperature to halt the body’s natural inflammatory response, which can cause the death of brain cells after cardiac arrest. The lowered temperature also slows down damage caused by lack of oxygen and the reestablishment of blood flow to the brain.
Candidates for the therapy are “those who have had a cardiac arrest and have been successfully resuscitated from a cardiovascular standpoint but are comatose after their arrest,” explained Chace T. Carpenter, MD, an intensivist at Baptist Hospital. Intensivists at Baptist are pulmonologists specially trained in critical care who treat seriously ill patients admitted to the intensive care unit.
“It’s not very high-tech, and it’s therefore not really an expensive therapy,” Carpenter said. “It involves giving chilled saline intravenously and using cooling blankets, basically.” Simple ice packs also work. She said the protocol calls for a body temperature ranging from 89.6 to 93.2 degrees F, or about 33 degrees C. “The patients feel pretty cold to the touch when you’re used to a baseline temperature of 98,” she said, adding, “The more quickly they’re cooled, the better.”
Usually after 24 hours, a slow warming process begins, which takes another 18 to 24 hours. Some patients wake up “fairly dramatically,” Carpenter said, while others awaken gradually. She estimates that Baptist has used the therapy 35 to 45 times.
Myers said Centennial has been using therapeutic hypothermia for more than a year. “I even pack people in the cath lab in ice,” he said. “The idea is to get the heart-attack artery open as soon as possible, but we try to initiate the hypothermia protocol as soon as possible, too. The sooner you can get it initiated, the better the chances of recovery.”
Centennial is equipped with a conductive hyper/hypothermia system by Gaymar, which includes a patient body wrap. According to the protocol, staff members monitor levels that may be altered by hypothermia, such as sugars and electrolytes. If needed, shivering is stopped by methods as simple as scheduled Tylenol or magnesium sulfate, or even a neurological paralytic agent should the shivering be severe. “I think the shivering is harder on the people looking at the patients than the patients themselves,” Myers said.
In December 2010, Corey M. Slovis, MD, medical director of the Metro Nashville Fire Department, sent a letter to hospital CEOs in Davidson County informing them that, effective April 1, responders with the Division of Emergency Medical Services “will only transport successfully resuscitated victims of cardiac arrest to those hospitals that commit to functioning as a Cardiac Resuscitation Center.” That means the hospitals must commit to instituting therapeutic hypothermia when appropriate as well as rapid transport to the catheterization laboratory.
Emergency responders also are launching the hypothermia protocol in the field. Sheldon Dreaddy, RN, Vanderbilt LifeFlight flight nurse, said, “If they [patients] meet the inclusion criteria, we’ll do it, but we don’t work independently, per se, of the cardiac team at Vanderbilt.” Those patient criteria include:
- an age of between 18 and 85,
- unresponsive and
- within 60 minutes of the cardiac arrest.
A patient isn’t a candidate if pregnant, in cardiac arrest secondary to sepsis, or suffering active internal bleeding.
“This is not rocket science at all,” Dreaddy said. “The goal is to get the core temp down to 33 degrees, so we’ll place an esophageal temperature probe and pack the groin, axilla and the neck with ice packs.” If LifeFlight lands on the scene, the team uses ice in the blood cooler. The patient may also receive cooled saline in transport. “If they lose their pulse while you are transporting them, you discontinue the cooling and start CPR. That’s important,” he added.
Dreaddy remembered the first LifeFlight use of therapeutic hypothermia in February 2010, when a 54-year-old Lebanon man collapsed in full cardiac arrest. “He was down for a significant time, to the point that I didn’t even think the hypothermia would help him,” Dreaddy recalled. “But a month later, he was in Belize on his anniversary with his wife. He did very well.”