Therapeutic hypothermia
From a mild hypothermia is called in medicine with a sub- cooling ( hypothermia) of the human body at 32 ° C or higher. The heart rate slows down at 32-34 ° C, the so-called QRS complexes in the electrocardiogram are wider, the potassium level in the blood decreases, the urine production increases and the blood sugar level may rise. In addition, a reversible dilation of the pupils may occur; wide light fixed pupils must therefore not be signs of a serious brain injury in a supercooled patients. If from the core body temperature below 32 ° C so threatening life-threatening complications such as cardiac arrhythmias, metabolic disorders, and cardiac arrest.
A cooling at much lower temperatures is called the depth of hypothermia.
Medical Application
Unconscious patients who were successfully resuscitated after cardiac arrest due to ventricular fibrillation, should be cooled after the ILCOR recommendation of 8 July 2003 for 12-24 hours at 32-34 ° C body core temperature. After the 24 hours they are slow, with a maximum of 0.25-0.5 ° C per hour, to be reheated. Here, the metabolism and oxygen consumption of the tissue decrease, and it will prevent a hypoxic tissue damage, especially of the brain. Possibly the low temperature also reduces the concentration of free oxygen radicals, which would otherwise cause further transitions in the sub- cell already damaged tissues. However, a new study from the U.S. shows a lack of effectiveness of this measure, in that it leads through the cooling increased side effects such as re- cardiac arrest and pulmonary edema.
Another field of application is in the care of newborns with asphyxia during birth. Through the therapeutic hypothermia not only the mortality of children can be reduced, but also the neurological outcome can be improved.
In patients with polytrauma, traumatic brain injury or massive blood loss which mild hypothermia is controversial because the complications, particularly susceptibility to infection and wound healing problems, usually predominate.
Patients with increased intracranial pressure or show acute myocardial infarction (AMI ) a better, patients after stroke even a significantly better outcome when they are treated with mild therapeutic hypothermia.
Cooling techniques
Superficial cooling
A superficial cooling with cooling blankets, cooling tents, cold wash or ice packs has disadvantages: all of these methods are only limited controllable. Especially when reheating there can be significant problems. The targeted reheating in 0.1 ° C to 0.5 ° C increments (see guidelines ) is not to control. In obese patients reaching the target temperature for the MTH is hard to create.
Gel Pads: A very good cooling is achievable. Upon heating, and also in the normothermic phase with modern gel pads, it is difficult to keep the guidelines of the ILCOR and ERC as missing automatic control targeted fever management more difficult. Pads are an alternative is in the initial cooling, but the skin must be continuously monitored under the gel pads.