Reading aloud Anyone who survives a cardiac arrest often retains severe brain damage. Now intensive care physicians protect the sensitive nerve cells with cold.

A beautiful summer's day in the city - in the park walkers stroll, the shopping streets overflow. Suddenly, a person in the crowd tips over: Horst P. (name changed by the editors), who actually wanted to get a birthday present for his wife. From one second to the next, his heart has failed, after 58 years of impeccable work. A bystander revives Horst P. again: He massages his heart and breathes air into his mouth. An emergency ambulance is also fast on site. With blue light and sirens howling Horst P. comes unconscious to the intensive care unit of the university hospital. There he is bedded on an air cushion mattress, from which cold air swirls under and over the body. Slowly his body temperature drops - 24 hours. Days later, Horst P. awakens from the coma. After eight weeks, he can leave the hospital. Only a slight speech disorder still reminds of the minutes when his brain was oxygen free.

Horst P. was lucky. He has survived the sudden death of the heart - this is the case only in 15 percent of the 80, 000 Germans a year who suffer a cardiac arrest outside the hospital. Many of the survivors remain paralyzed, unable to speak or have lost their memory. Because only five minutes without blood supply are enough to destroy nerve cells once and for all. The brain of Horst P. has hardly suffered any damage because the cold protected it. He was treated in a hospital participating in a large European study of cardiac arrest survivors. She tested the concept of "hypothermia": as soon as possible after the cardiac arrest, the physicians involved lower the body temperature of their patients to 33 degrees - with cool air flowing from a special mattress. Only 24 hours later, the patients may be warmed up to the normal "operating temperature" of 37 degrees. The study group recently presented their findings in the journal New England Journal of Medicine. With hypothermia, the doctors could not only increase the number of survivors. Those who were able to leave the hospital also retained significantly fewer neurological disorders: 55 percent of hypothermic patients could be discharged home or to a rehabilitation facility with a "favorable neurological outcome." A concurrently published study from Australia showed equally encouraging results at 49 percent. In the comparison group without cooling, it was only 36 or 26 percent. The Australians used more spartan cooling methods than the Europeans: They simply washed their patients off cold and packed them with ice packs. Physicians first noticed that cold can protect the nerve cells in the case of injured children who had broken in on a frozen lake while playing. Even those who were only pulled out of the icy water after half an hour or more often survived without any after-effects. Nevertheless, hypothermia has so far played a major role in emergency medicine: "The brain is too often forgotten, " criticized Matthias Fischer, intensive care physician at the University Hospital Bonn. The current revival practice focuses on the heart and circulation. Especially the nerve cells are particularly sensitive in the first 24 hours after a successful resuscitation: The lack of oxygen during cardiac arrest has brought their energy balance to a standstill. When enough oxygen is available again, free radicals are formed, which attack the already damaged cell membranes. Also, calcium and the messenger glutamate, which play an important role in the cooperation of neurons, are produced in excess and lead to uncontrolled discharges. All this strains the cells, many die off - forever, because once perished neurons can hardly be replaced, unlike the cells of most other body tissues. "Cold works more effectively against these processes than any known drug, " comments Fischer, who was involved in the European study. Other people who are in a coma - for example, after a stroke or a traffic accident with craniocerebral trauma - could benefit from hypothermia. The cold lowers the excessive pressure in the cranial cavity resulting from a cerebral infarction or mechanical injury. However, there are still no broad-based studies. However, the two studies could be groundbreaking for cardiac arrest management. Within the next two years, cooling is most likely included in the guidelines of the International Liaison Committee on Resuscitation (ILCOR), an association of the largest emergency medical societies. But it can take years until it becomes routine everywhere in Germany. The simpler the cooling methods, the sooner they could prevail, says Fischer: "It would be a step forward if the ambulance in the emergency vehicle left the window open, so that the patient cools by the draft."

Evelyn Hauenstein

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