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Hospitals Turn Down Patients' Temperatures to Warm Up Survival in Cardiac Arrest

Monday November 3, 2008
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New Jersey hospitals are cooling down patients to increase survival rates from sudden cardiac arrest. An estimated 300,000 Americans die from sudden cardiac arrest each year — more than from car crashes, firearms, house fires, AIDS, and breast, prostate, and colorectal cancer combined (www.takeheartamerica.org/).

One strategy to increase survival is to cool down the patient using therapeutic hypothermia, also known as TH. The American Heart Association endorsed therapeutic hypothermia in 2003, yet adoption has lagged. But that's not true in New Jersey.

"We've treated 40 patients with the technique since January 2006," says Mary Stauss, RN, MSN, APN, a clinical nurse specialist at Cooper University Hospital in Camden, N.J. At this time, Stauss says that it's too early to release the results of whether the procedure has improved survival rates.

This temperature management system includes hydrogel pads, which are placed on the patient's chest, back, and legs. An automated heat-exchange system helps to keep the temperature at the desired level. Water is pulled through the device under negative pressure, which ensures the patient is kept dry, even if a pad is accidentally punctured.
Temperature Not Rising

A common method to lower temperature is surface cooling with an external device. "The system lets us concentrate on the patient, not the machine," says Kristen deGrandpré, RN, MSN, CCRN-CMC, clinical nurse specialist, Gagnon Cardiovascular Institute in Morristown, N.J. The hospital has treated 10 patients since January 2008.

Cooling starts as soon as the patient survives a cardiac arrest and meets certain criteria, whether it's in the ED, cath lab, or ICU. Timing is essential. TH should begin as soon as possible (but usually not after 6 hours) in a patient who has return of spontaneous circulation within approximately 50 minutes of cardiac arrest, but remains comatose and has a systolic BP of at least 90mm Hg without significant vasopressor support.

"Once the patient is identified [as eligible for TH], it takes only 30 to 35 minutes to have everything in place," says deGrandpré. In most hospitals, the ED physician can make the decision to start TH, weighing the benefits and dangers of treatment. Exclusion criteria include major head trauma, cardiogenic shock, active bleeding or coagulopathy, arrests that are not primarily cardiac in origin, or a major operative procedure within 14 days preceding the arrest.

During TH, patients experience mild cooling, that is, from 33C to 36C (91.4F to 96.8F). "We cool for 24 hours, then rewarm," says deGrandpré. At Cooper University Hospital, patients are cooled to 91.4F to 93.3F for 24 hours once the target temperature is attained. Some hospitals time the 24 hours from the start of cooling, while others time it from when the target temperature is reached.

Protocols around the country typically recommend that during rewarming, a patient's temperature should increase no more than 0.5C to 1C per hour to a target of around 36C to 36.5C.

(Left) Kristen deGrandpre, RN, clinical nurse specialist, Gagnon Cardiovascular Institute in Morristown, prepares a patient for TH.
Monitor, Monitor, Monitor

Most TH protocols call for inserting a Foley catheter with temperature-monitoring capability, although Stauss cautions that these require 10mL of urine per hour to be accurate. Another method of monitoring temperature is through a pulmonary artery catheter.

Patients who must be intubated and on mechanical ventilation receive sedation. Paralytics are usually reserved to treat shivering. "Cooling often results in significant diuresis. Urine output must be measured every hour and replaced with normal saline," says Stauss.

Potential complications include bleeding, pneumonia, skin breakdown, and electrolyte imbalance. Patients are at risk of hypokalemia during cooling and hyperkalemia during rewarming.

According to deGrandpré, process changes have included not heating the oxygen delivered to the patient, expediting the release of drugs from pharmacy, and not extubating patients until rewarming is complete. It's time-intensive, says deGrandpré. "A 12-hour shift can feel like it's 12 minutes."

Prep Time and Super-Users

Preparing to implement TH requires multidisciplinary cooperation, says Donna Ramsey, RN, CEN, ED nurse manager, Hackensack University Medical Center. The hospital is getting ready to begin TH after frequent meetings to develop a protocol. "We collected data from hospitals throughout the country that have already successfully implemented this process to see what works best clinically," says Ramsey.

Hackensack's multidisciplinary team includes pharmacists, critical care APNs, clinical nurse educators from the ED and ICU, the physician chairman of the ED, and critical care physicians.

Of course, education is essential before the start of a TH program, but follow-up education is important too. "This isn't a common procedure," says Stauss. "Super-users" in the ED, CCU, and cath lab at Gagnon understand TH and work with staff who have less experience. "Our nursing staff is really excited about it," deGrandpré says. "We do reminders and updates after each case as well."

Families need to understand what the treatment entails. "Open visiting is allowed and a nurse or social worker is always available to the family, because this is a new patient treatment that seems out of the ordinary," says deGrandpré. She recommends honest communication with the family about the hospital's experience with TH, including the number of cases and the outcomes. "Therapeutic hypothermia gives them something to hang onto, to give them hope," she adds.

Future of TH

Clinicians' understanding of TH is at the tip of the iceberg. "There is so much we don't know about how patients respond," says Stauss. "A 62-year-old man with a lot of problems might do better than a 32-year-old patient." This difficulty in predicting response is due to the many variables of sudden cardiac arrest, such as the length of time the patient is "down" before help arrives, the initial rhythm, the cause of the arrest, and the quality of CPR the person received. Given the positive results of TH, it's likely the quest for more information will continue.

"It takes all of your nursing brainpower and emotional strength to cope with it [TH] and support others through the process," says deGrandpré. "But it gives patients more opportunity to do better. That makes it worth all the time and effort."

Cynthia Saver, RN, MS, is president of CLS Development, Inc. To comment, e-mail editorNJ@nursingspectrum.com.
The Case for Cool

How might TH work? Reperfusion triggers inflammatory mediators that cause a variety of complications and perfusion abnormalities. Hypothermia suppresses this inflammatory response and has led to reduced morbidity and mortality among adults who were resuscitated from sudden cardiac arrest and among newborns with hypoxic-ischemic encephalopathy.