Induced Hypothermia Part IV

Read below for more information on induced hypothermia for cardiac arrest.

Most recent studies:

Background: Several investigators have emphasized the positive effect of hypothermia therapy on patients who have suffered from cardiac arrest. Salvaging patients from circulatory collapse is a pivotal task, but it is unclear whether additional hypothermia can practically contribute to an improvement in the neurological outcome. Methods and Results: Since December 2005, our hospital has been using hypothermia therapy. Forty-six comatose patients after recovery of spontaneous circulation were consecutively enrolled in the present study. Twenty-five of the enrolled patients received hypothermia therapy and 21 did not because they were treated prior to 2005. The time from collapse to spontaneous circulation (P=0.09), the rates of performance of bystander CPR (P=0.370) and presence of a witnessed collapse (P=0.067) were not significantly different between the recovery group (n=28) and the non-recovery group (n=18). The additional hypothermia therapy was an independent predictor of neurological recovery (P=0.005, OR 6.5, 95%CI 1.74-24.27). The recovery rate was significantly higher in patients who received hypothermia therapy (80%) compared to those who did not (38%). Conclusions: Hypothermia therapy is very useful for treating patients who have had an out-of-hospital cardiac arrest; it should be induced rapidly and smoothly.

BACKGROUND: ILCOR recommend the use of therapeutic hypothermia (32-34 degrees C) for 12-24 h in unconscious adult patients with spontaneous circulation after cardiac arrest with a VF rhythm. Among various methods of inducing hypothermia, the rapid infusion of ice-cold intravenous fluid has been used. METHODS: To investigate the time required to cool intravenous fluids in a domestic refrigerator and freezer, bags of compound sodium lactate were placed on the upper shelf of a refrigerator. Continuous temperature measurement was performed for 2 h for 10 500 ml and 10 1000 ml bags. The procedure was then repeated in the freezer. RESULTS: The mean time for 500 ml bags to cool to 4 degrees C or below was 90 minutes or more in a refrigerator and 60-90 minutes in the freezer. 1000 ml bags are cooled to 4 degrees C or below within 120 minutes in the freezer, but it takes longer in a refrigerator. CONCLUSION: As induced hypothermia should be started as soon as possible in eligible patients, crystalloids should be stored in a refrigerator.

An interesting story about a different in hospital cooling method:

[Sarasota Memorial Healthcare System]
Below is a story which involves a new and innovative technology to help prevent brain damage in cardiac arrest patients.

On a recent evening at his Sarasota home, Jim Owens went to bed as usual. During the night, he suffered sudden cardiac arrest. The 63-year-old man's heart had stopped beating effectively, unable to pump oxygenated blood to the brain. His wife called 911, and paramedics rushed Mr. Owens to Sarasota Memorial Hospital. He was resuscitated, but had slipped into a coma, at risk for serious brain damage.

In Sarasota Memorial's Intensive Care Unit, physicians and nurses employed state-of-the-art cooling technology to chill his body quickly yet precisely to 93 degrees, protecting his brain function and helping to heal damaged tissue. Sarasota Memorial currently is the only hospital in the county using this new cooling catheter.

Owens was rewarmed and woke up about 18 hours later. After thorough evaluation, it was clear he had suffered no neurological damage. Physicians soon implanted a pacemaker and defibrillator to restore his cardiac function.

While Owens, a retired sales marketing executive with Procter & Gamble, has little memory of his high-tech treatment at Sarasota Memorial, he is happy to have fully recovered from his cardiac arrest and resume his normal activities -- particularly those requiring a great deal of mental acuity.

“I knew I would be fine when I came home from the hospital, and within a short time, I was answering final Jeopardy questions correctly,” he said.

Cardiac arrest causes about 350,000 deaths in the United States, with the vast majority of victims dying before they ever get to the hospital. It occurs suddenly and brain death can occur in four to six minutes. Even after successful resuscitation, the brain can be damaged from chemical reactions that occur when the blood starts to flow again.

Recent landmark studies show that reducing the body’s temperature below normal can prevent brain damage and save lives. In fact, the American Heart Association recently recommended that medical personnel cool cardiac arrest patients. Several studies also stress the importance of avoiding fever, which can be common, difficult to control and responsible for additional brain damage in cardiac arrest victims.

“Research consistently shows that therapeutic hypothermia can lessen or prevent neurological damage from cardiac arrest and subsequent oxygen loss to the brain,” said Mauricio Concha, MD, medical director of the Acute Stroke Program at Sarasota Memorial. “The catheter technology gives us a vital tool to aid brain healing and enhance patients’ recovery.”

Induced hypothermia has been used to treat cardiac bypass patients, but only recently has the therapy been employed for cardiac arrest.

Here’s how the cooling catheter technology works:

First, a temperature probe catheter is inserted into the bladder of the patient to monitor body temperature. The catheter is connected via a thin cable to the Alsius CoolGard 3000® temperature control system. Next, a heat exchange catheter, a long, thin, soft tube with three balloons, is inserted through a vein at the top of the leg and guided over a wire to its resting place below the heart. Cooling saline runs from the CoolGard 3000 system through tubing into the catheter, down through the balloons. The fluid is then re-circulated back to the system in a closed-loop. Blood is cooled as it passes by the balloons. No fluid is infused into the patient, nor is blood circulated outside of the body. In addition to allowing staff to cool the body more precisely than previous methods, reducing the brain's need for oxygen, the catheter also gives better control over the warming process, permitting physicians to bring patients’ temperatures back up a fraction of a degree at a time.

“The intravascular cooling catheter has been an effective means of inducing hypothermia in patients resuscitated after cardiac arrest, and is an example of the kind of state-of-the-art technology that has made Sarasota Memorial a nationally ranked provider of top-quality care,” said Kenneth Hurwitz, MD, medical director of Critical Care Services at Sarasota Memorial.

Previously, staff would have used chilled blankets and ice packs, a cumbersome, less exact method to lower body temperature.

The catheter technology was purchased with a generous donation from Louis and Gloria Flanzer.
JEMS Webcast - Brent Myers, the medical director for Wake EMS, delivers an excellent presentation.

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