Hypothermia after traumatic brain injury. Report of the Neuroonaesthesia Working Group of the German Society of Anaesthesiology and Intensive Care Medicine

The benefit of therapeutic hypothermia after traumatic brain injury in adult patients remains a controversial issue in the literature. Nevertheless, there is widespread use of cooling after head trauma. In published clinical trials, hypothermia is used for the prevention of secondary brain injury or the reduction of intracranial hypertension which cannot be controlled otherwise. In approximately half of these studies, hypothermia resulted in a better outcome. The US multicenter trial published in 2001 did not show any improvement in the outcome for patients with severe head injury after hypothermic treatment with a core temperature of 33 degreesC for 48 hours in comparison to normothermic patients. However, due to certain features in this study, the information it provides is limited. Several meta-analyses from the years 2001, 2002 and 2003 did not show any effect of mild to moderate short-term hypothermia. Two meta-analyses published in 2003 explored the effects of depth and duration of hypothermia as well as the effect of rewarming. In the case of hypothermia lasting at least 24 hours, the risk of death was reduced by 19% and with a duration of at least 48 hours there was a 30% reduction in the risk of death. Additionally, hypothermia lasting at least 48 hours decreased the risk of a poor neurologic outcome by 35%. The combination of a target temperature range of 32-33 degreesC, hypothermia lasting at least 24 hours, and rewarming within 24 hours also reduced the risk of a poor neurologic outcome. An overview of the studies currently available does not permit the definition either of standards or of therapeutic guidelines for the routine use of hypothermia after traumatic brain injury. If hypothermia is applied as a preventive measure, treatment should be based on the criteria associated with therapeutic benefit in the meta-analyses.