“Cooling down”: therapeutic hypothermia for cardiac arrest patients

It has been recommended by the American Heart Association (AHA) since 2003. It was incorporated in the guidelines in 2005 Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Yet, this clinical practice, which can save lives, are seldom used in hospitals and clinics.

The technique is called therapeutic hypothermia and is recommended for use in cardiac arrest survivors who are unconscious or in comma.

How does therapeutic cooling work?

Here is how “chilling out” works:

The patient’s body temperature is cooled down so that internal body temperature remains between 32° and 34°C (89.6° and 93.2°F) and the patient is monitored that the temperature remains stable for at least 12 to 24 hours. In doing so, damage is minimized and survival and neurological outcomes improved.

Is it effective?

A study by Australian researchers in 2002 showed that therapeutic hypothermia improved outcomes in patients with coma after resuscitation from cardiac arrest. 49% of patients who underwent hypothermia were discharged to go home to a rehab facility. Only 26% of those maintained at normal temperature were discharged. Other studies suggest similar results.

So why is therapeutic cooling not so popular in clinical practice?

Researchers at University of Pennsylvania School of Medicine, Philadelphia thought it might be due to the fact that therapy is not cost effective. Thus, they conducted a study to evaluate the cost-efficiency of this method. They balanced the cost to provide therapeutic hypothermia, which included treatment, posthospital discharge care, additional nursing care required during cooling treatment, and the extra time spent in the intensive care unit versus the efficacy and costs of no cooling therapy. Their analysis indicates that the therapy is effective in the long run. Specifically,

• Patients who underwent therapeutic hypothermia gained more quality-adjusted life years than those treated with conventional therapies.
• Cost effectiveness of hypothermia remained less than $100 000 per quality-adjusted life-year in 91% of the situations analyzed vs. conventional therapies.

According to study author Dr. Raina Merchant

“The cost of therapeutic hypothermia compares favorably with other medical treatments that are commonly used, such as kidney dialysis, estimated at $55 000 per quality-adjusted life-year, and public access defibrillation, at $44 000 per quality-adjusted life-year. Even when we controlled for care outside of the hospital, the cost of the therapy was still within the accepted range of cost-effectiveness.”

In some American cities, therapeutic cooling is becoming part of emergency procedures. Ambulances in New York City deliver cardiac arrest patients only to hospitals with cooling facilities. This is a bit controversial because smaller hospitals which don’t have and can’t afford cooling facilities may be at a disadvantage.

Dr. Merchant hopes that therapeutic hypothermia will soon become the standard of care everywhere.

“The American Heart Association recommends this therapy with very good data to show that it saves lives. People are able to return back home and to their regular jobs in many cases, without the permanent brain damage that would often ensue after a cardiac arrest. It’s not uncommon for studies to come out saying that something is effective, but hurdles remain in trying to figure out how to implement the therapy. Cost is often a part of that discussion, so we wanted to show that cost should not be an obstacle to cooling, a therapy we already know is effective.”

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