Interventions that aim to reduce body temperature to between 35 ºC and 37.5 ºC in patients who have had a traumatic brain injury within the last week

Traumatic brain injury (an injury to the brain that occurs as a result of a direct impact, such as may occur after a road traffic accident or a fall) is a major cause of death and long-term disability worldwide. There is some evidence from animal experiments that reducing body temperature after brain injury may improve outcomes. There is also some evidence in humans to suggest that people with a normal body temperature after traumatic brain injury may have a better outcome than those with a higher temperature. 

The authors of this Cochrane review looked for evidence that reducing body temperature to between 35 ºC and 37.5 ºC would benefit patients in the week after traumatic brain injury. We looked for studies on the use of physical or drug-induced cooling on patients with a traumatic brain injury. Physical cooling techniques include cooling blankets, use of ice, fans or other devices. Chemical cooling techniques include drugs used to reduce fever, like paracetamol (acetaminophen).

We did not find any randomised controlled trials or controlled clinical trials that we could include in this review. Such studies represent the best form of evidence to determine whether a particular therapy works, because they limit the errors that may affect the interpretation of a study. Given the lack of eligible studies, the only finding we can present is that there is no satisfactory research carried out in relation to the specific question of the risks and benefits of cooling to between 35-37.5°C for patients with TBI. There is another Cochrane review (Hypothermia for traumatic head injury) about cooling below 35°C which includes a number of studies.

Authors' conclusions: 

In order to further explore the preliminary findings provided by animal models and observational clinical studies that suggests there may be a beneficial effect of modest cooling for TBI, randomised trials designed to explore the effect of these interventions on patient-centred outcomes are needed.

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Background: 

Animal models of traumatic brain injury suggest that induced normothermia (36.5 or 37 ºC), compared to induced hyperthermia (39 ºC), improves histopathological and neurobehavioural outcomes. Observational clinical studies of patients with TBI suggest an association between raised body temperature and unfavourable outcome, although this relationship is inconsistent.

Objectives: 

To assess the effects of modest cooling therapies (defined as any drug or physical therapy aimed at maintaining body temperature between 35 ºC and 37.5 ºC) when applied to patients in the first week after traumatic brain injury.

Search strategy: 

The most recent search was run on 23rd September 2013. We searched the Cochrane Injuries Group's Specialised Register, The Cochrane Library (CENTRAL), MEDLINE (OvidSP), Embase (OvidSP), ISI WOS: SCI-EXPANDED (1970) & CPCI-S (1990), PubMed and trials registries together with reference checking.

Selection criteria: 

All completed randomised, controlled and placebo-controlled trials published or unpublished, where modest cooling therapies were applied in the first week after traumatic brain injury.

Data collection and analysis: 

Two authors independently applied the selection criteria to relevant trials.

Main results: 

We were unable to find any randomised controlled trials of modest cooling therapies after traumatic brain injury.

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