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Researchers at the Faculty of Medicine - University of Freiburg have developed a therapeutic approach that allows people to be resuscitated much more successfully than before after a cardiac arrest - often without neurological complications / Study in Nature Reviews Neuroscience summarizes decisive factors / New "heart-lung machine" enables clinical implementation

Around 50,000 people suffer a sudden cardiac arrest in Germany every year. If it happens outside a hospital, the chances of survival are only ten percent. In addition, survivors often suffer from severe permanent neurological damage. On July 21, 2021 , researchers from the Faculty of Medicine - University of Freiburg, together with German and US colleagues, published a review article in the journal Nature Reviews Neuroscience in which they describe the most important therapeutic factors for successful resuscitation. The scientists refer to the therapy concept based on this as CARL (Controlled Automated Reperfusion of the whoLe Body). In recent years, the physicians and cardiotechnicians in Freiburg have also developed a special mobile heart-lung machine for resuscitation that makes CARL therapy possible for the first time. In one of the first missions, a person successfully survived a cardiac arrest after around 120 minutes of resuscitation. The person concerned suffered no brain damage.

"After decades of research, we were able to develop a new treatment method in Freiburg to reduce the damage that would otherwise occur after cardiac arrest and resuscitation. Our findings and the device we have developed could be of great importance for emergency medicine," says Prof. Dr. Friedhelm Beyersdorf, Medical Director of the Department of Cardiovascular Surgery at the Medical Center - University of Freiburg. "This CARL method incorporates the latest basic research and state-of-the-art cardiac surgery techniques. Thanks to our own innovative medical technology developments, we now have the opportunity to apply this new treatment principle both inside and outside the clinic. This offers the prospect of people surviving much longer and better after a cardiac arrest than previously assumed," says Beyersdorf.

Success factors for resuscitation

As a result of a cardiac arrest, the blood vessels in the brain swell and are therefore less permeable for gas exchange. "High, pulse-like blood pressure during controlled whole-body reperfusion (CARL therapy) is the quickest way to restore blood flow to the brain," says Beyersdorf. The oxygen level must be low and must only be increased slowly, otherwise free radicals will form in the tissue. These very aggressive molecules can then attack the mitochondria, among other things, which act as the power plants of the cells. A reduced concentration of calcium in the blood also helps to protect the mitochondria. "It is very important to lower the patient's body temperature as quickly as possible in order to slow down metabolic processes," explains the Freiburg heart surgeon, who published the study together with colleagues from Yale University, USA, and the Max Planck Institute for Metabolic Research.

CARL - For the first time, resuscitation therapy is possible in all its complexity

Some of the aspects were known in principle, but not in such detail. In addition, the many aspects of therapy were not technically feasible until now. This is why scientists at the Medical Center - University of Freiburg founded the startup Resuscitec a few years ago and developed a device that specifically meets the complex requirements of resuscitation: the CARL system.

"To our knowledge, CARL is the first device that has been specially developed for resuscitation and can take over the patient's entire cardiopulmonary function. Above all, however, it is the only device in the world that makes it possible to treat the damage caused by cardiac arrest and the associated lack of oxygen. This is possible because we can immediately measure and control all the important parameters, such as blood values, that are necessary for successful resuscitation," says Prof. Dr. Christoph Benk, Head of Cardiotechnology at the Department of Cardiovascular Surgery at the Medical Center - University of Freiburg. A unique double pump control system enables the necessary high pulsatile blood flow and achieves a high blood pressure. The oxygen level can be precisely controlled and the patient's body can be cooled down quickly and safely using a mobile cooling unit. "The size and weight of the device is designed so that it fits in the ambulance and can be carried directly to the patient," explains Benk.

First CARL missions give great hope

In an initial pilot study, CARL therapy saved many of those affected. At 50 to 120 minutes, the resuscitation time was very long. "In one 43-year-old patient, resuscitation was successful after 70 minutes. The patient made a full recovery and is back to work as a teacher," said Prof. Dr. Georg Trummer, Head of Intensive Care Medicine at the Department of Cardiovascular Surgery at the Medical Center - University of Freiburg. In another case, a patient suffered a cardiac arrest at home and was brought to the Medical Center - University of Freiburg by helicopter after first aid resuscitation. "Here, the patient was immediately connected to the CARL device and - after 120 minutes - successfully resuscitated," says Trummer. The patient suffered no brain damage and was able to return to her job. A study is now planned at three European universities as part of the European Commission's Horizon 2020 program to confirm these initial promising results.

Conflicts of interest

Prof. Dr. Friedhelm Beyersdorf, Prof. Dr. Christoph Benk and Prof. Dr. Georg Trummer are involved in the company Resuscitec.

Original title of the study: Brain vulnerability and viability after ischemia
DOI: 10.1038/s41583-021-00488-y
Link to the study: www.nature.com/articles/s41583-021-00488-y

Further information:

• Published case study https://pubmed.ncbi.nlm.nih.gov/28693585/
• Video: Prof. Dr. Friedhelm Beyersdorf summarizes the publication
• Video: Prof. Dr. Georg Trummer reports on the clinical application of CARL therapy
• Video: Prof. Dr. Christoph Benk presents technical aspects of the CARL system

Source videos: Medical Center - University of Freiburg

Contact:
Prof. Dr. Friedhelm Beyersdorf
Medical Director
Department of Cardiovascular Surgery
University Heart Center Freiburg - Bad Krozingen
Uniklinik Freiburg
Phone: 0761 270-28180
friedhelm.beyersdorf@uniklinik-freiburg.de