Cold times in critical care
Cold is not only a winter topic. Cold is also applied medicine: Moderate to deep hypothermia made cardiac surgery possible and mild therapeutic hypothermia improves survival after out-of-hospital cardiac arrest. By Holger Zorn.
Jean-Dominique Larrey, Napoleon's lightning fast and skilful surgeon, inventor of the “flying ambulances”, had much to do in the Prussia-Poland campaign of the years 1806-07. It is reported that he could disarticulate legs from the hip joint in less than four minutes. But despite all his skill, some patients passed away easily, especially those who were able to get a place at the campfire. Freshly operated soldiers survived better if they had to sleep away from the fire in the snow, Larrey noted in a “Memorandum on the dry gangrene caused by cold”, and also that patients who underwent such an operation had as less pain the colder it was. Despite some anecdotal reports, that was the first systematic analysis of the effect of cold in medicine, published in Larrey’s Mémoires de médecine et de chirurgie militaire.
Ice Age in cardiac surgery
A hundred years later, William Gordon Bigelow was born in Brandon, Manitoba province, Canada - where winters may as hard as in East Prussia at Napoleon’s time. He became a physician as Larrey, and military surgeon too. After World War II he returned from Normandy to Toronto General Hospital and conducted pioneering research in hypothermia, hibernation, and cardiac pacemaker technology. Thinking of hypothermia as a means of anaesthesia, he laid the foundation for cardiac surgery. Today's patients are anesthetized with modern drugs and not placed in ice buckets to perform a surgical procedure, but only fifty years ago a cardiac Operating Room looked like that.
“We save the heart but we lose the brain”
This sentence, pointed out by the famous American surgeon Gerald Buckberg, was a hard reproach but unfortunately true. Driven by ILCOR, ERC and national councils, the technique of mild therapeutic hypothermia has been widely accepted and adapted - and has become more invasive. Our own program, started at Martin Luther University Hospital in Halle (Saale), Germany, in 2006, used an invasive cooling catheter, inserted into the femoral vein and advanced into the vena cava inferior. In 17 cases, 8 female and 9 male patients with an age of 37-84 years and with different causes of cardiac arrest, mild hypothermia was induced. The body temperature was lowered down to 33°C in the first two hours and was maintained at this level for about 20 hours. At the beginning, the lactate level is mostly raised, and its normalization at a normal value around 2 mmol/l is a good sign of metabolic recovery, thus a trigger to stop the perfusion. When the catheter removed, the body will be rewarmed passively in about 4-5 hours. We found this technique safe and effective. There are advantages especially for the cardiac unstable patient. 
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