Keeping It Cool

In Vienna, a New Technique Increases Survival Rates of Cardiac Arrest Victims

Wiener Rettung

The Wiener Rettung is the first ambulance service in the world to implement this non-invasive life-saving technology | Photo: EMCOOLS

It’s a simple concept, and literally, very cool. Since September 2006, the Vienna Ambulance Service (Wiener Rettung) has used latex mats, filled with graphite and water, to cool the body temperature of cardiac arrest victims, raising their survival chances after resuscitation by 30 percent, as well as reducing the likelihood of severe impairment.

The Wiener Rettung is the first ambulance system in the world to implement this non-invasive technology, becoming a model for other nations.

At a major international conference here on Mar. 16, specialists from 14 European countries met at the Vienna’ General Hospital (AKH) to discuss implementation and support the application this month for major funding through the EU’s Seventh Framework Programme for research and technological development.

Cardiac arrest is the cessation of blood circulation in the body. As a result, no oxygen reaches the organs. Brain damage can begin after only 3 minutes, and after 10 minutes, the chances of survival are less than 10 percent. Doctors and paramedics resuscitate the patient with chest compressions, ventilation, and defibrillation. Then, cooling mats placed over the patient’s body, lower the body temperature to 33 degrees Celsius — “therapeutic mild hypothermia,” they call it.

Prof. Dr. med. Fritz Sterz, from the University Clinic for Emergency Medicine at Vienna General Hospital (AKH), initiated the practice. He was a pupil of the late Peter Safar, who some call the “Father of Resuscitation,” who was the first one to show conclusively that mouth-to-mouth resuscitation works. Around 1991, Safar conducted further studies, simulating cardiac arrest in dogs, and then cooling them with ice cubes around their heads. The dogs came out healthy, their cognitive functioning intact.

It was during the many animal experiments that he and his team, including Prof. Sterz, hit on the effects of cooling. The experimental results were not, however, always uniform, so Safar and his team investigated the reason, and found that minor temperature variances were affecting the outcome. They then spent the next three years looking at why and how cooling worked.

Although there is still some mystery surrounding the reasons for the effectiveness of cooling, the main concepts are understood. After resuscitation, a large amount of damage occurs to cells because of chemical reactions when oxygen is delivered to them quickly. If you cool the cells post-resuscitation, these reactions happen more slowly, and the cells are therefore protected. The more damaged cells that exist, the greater the risk is for death or severe neurological defects.

Inspired by Safar’s study, Prof. Sterz began his own. “We did a lot of experiments that showed it was beneficial. I thought, why not try it now on humans?”

The first in-hospital cooling in Vienna was performed around 1995. In those early trials, patients were cooled with large ventilators and ice cubes, as no special equipment was available at the time. No harm done to the patients, and with continued favorable outcomes, the European Commission funded further studies. In 2000, Prof. Sterz published a compelling report with his colleagues Dr. Michael Holzer and Dr. Wilhelm Behringer in the New England Journal of Medicine, making cooling standard practice.

According to Dr. Thomas Pellis, a physician from Italy, “Dr. Sterz’s work has already revolutionized cardiopulmonary resuscitation and post-resuscitation care.”

Buoyed by doctors in Australia and Scandinavia who have tried cooling in ambulances and confirmed his results, Prof. Sterz took the next step, searching for ways to implement cooling in ambulances beyond the “poor man’s methods”— cold fluid injections and ice cubes – that are not always effective. Rudolf Faworka, an inventor in Vienna, created an alternative: cooling pads that could hold a cold temperature sixty times better than frozen water, and could cool the patient 4∞C per hour. These pads are the fastest method currently available. Even if a faster system existed, quicker cooling could be dangerous, because there is the potential to surpass the target temperature.

In the early stages of use, separate pads were designed for different parts of the body, but proved cumbersome. Now, the six big pads and four small ones can be used interchangeably. The daily experiences of the several Vienna Rescue squads involved in their development will influence how they may evolve for the future.

“This is a development we would like to distribute throughout Vienna, and maybe the world,” said Prof. Sterz.

So far the pads have produced favorable results, but there are still problems with product development. Prof. Sterz identified the biggest challenge as the transition to a more professional pad-production, to avoid problems such as faulty temperature monitors or leaks.

“It works, but in medicine it has to work perfectly,” emphasized Prof. Sterz. The pad problems are not in themselves harmful to the patient, and they still perform their major job: cooling. Prof. Sterz likens the product troubles to driving a car on a rainy day. “If the windshield wipers are not working, you cannot see anything, but you can still drive the car. But then there is the potential for an accident if you are not very careful.”

He is optimistic about developing the product in Vienna, as the physicians and paramedics want it to work, and are devoted to its usage. Hofrat Dr. Alfred Kaff, head of the Vienna ambulance service, seems pleased with his employees’ work with cooling. “There are many very engaged doctors and teams with this ambulance service that perform their work diligently,” he said.

Other questions are still up in the air, not concerning development, but implementation. Prof. Sterz wants to conduct a European study to provide answers to as yet unanswered questions –  how cool should patients be kept? What’s the best method for cooling? How fast should it be done, and when?

At the Mar. 16 conference, the visiting specialists assembled at the AKH for the inaugural “investigators meeting” to discuss the content and coordination of Sterz’s cooling study. According to Dr. Pellis, the mood at the meeting was dynamic. “I have never seen so many leading experts in one room debating for the sake of science. I learned much more than at any other medical conference I have ever been to.”

Dr. Pawel Krawczyk was equally enthusiastic: “People only know about published data, but such an informal meeting may become a very effective way to exchange and develop new ideas.”

Even though the outcome could be groundbreaking, challenges remain. Coordinating ambulance procedures in the eighteen test countries will not be easy. In Bonn, the emergency service used frozen foods to cool a patient in a supermarket. In Italy, Dr. Pellis’ patients were uncovered and ambulance windows opened to let the cold air in; The only emergency medical system in Italy that even has a protocol for pre-hospital cooling,  resort to very “simple methods,” Dr. Pellis said, and he considers the techniques used in Vienna much more straightforward to implement. “So far, Vienna is for most centers, and certainly for us, a model and leading authority in cooling,” he remarked.

Even with successful results, the work has just begun. Prof. Sterz still needs funding. His research is important – 700,000 people have cardiac arrests annually in Europe – but, pitted against research areas like genetics or infectious diseases, which traditionally receive most funding, obtaining the €10 million available through the EU’s Seventh Framework Programme for research and technological development is not easy.

The committee in charge is looking for something very specific, so Prof. Sterz identified the major problem right now as trying to fit his study to their guidelines. He has until Apr. 19 to submit a proposal.

“Unfortunately there is too little lobbying for cardiac arrest patients, so our topic is not of major interest to the commission,” said Sterz. “Everyone should call their program delegates and tell them that cardiac arrest is also a problem.”

Concerned about the lack of support for emergency medicine, Prof. Sterz believes that an important way to create interest is to introduce these topics to schools as a part of the curriculum. He has already taught hundreds of children in Vienna, and developed an educational DVD.

“You have to learn history, German, and how to dissect insects, why not learn how to save lives?” he asked assertively.

Even in the midst of the cooling studies, Prof. Sterz emphasized that people should not forget about mouth-to-mouth resuscitation, chest compressions, and defibrillation.

“Cooling doesn’t do everything. Although important, it’s only one part of the whole chain. Defibrillation is especially important,” he said. With the wide availability of automated external defibrillators (AED) leading the layperson through every step, it is easy to save a life. “You see fire extinguishers everywhere, but not AED’s. Why is a fire extinguisher so much more important than an AED, even if it’s so easy to use?”

Although no method can work perfectly in every emergency, the application of cooling pads after successful resuscitation has had a remarkable record – results that can make the difference between life and death and give cardiac arrest survivors the chance once again to lead active, normal lives.

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