Prevention of HYPOthermia in TRAUMa Patients

Trauma patients are often hypothermic (temperature < 35 °C) upon arrival at the hospital. Hypothermia is with hypotension and hypoxia, perfectly known to be directly responsible for complications.

Hypothermia is responsible, with acidosis and coagulopathy, of the " lethal triad" of trauma.

Thus, it is clearly established that hypothermia is directly associated with poor prognostic in trauma patients. In a recent study, mortality rate reached 100% for trauma patients arriving at the hospital with a body temperature below 32°C.

The weather, the severity of the trauma and medical (or paramedical) interventions are responsible for the onset of this hypothermia.

Then, continuous monitoring of the patient's temperature, active protection against hypothermia with a metal blanket, the warming (and measure the temperature of) infusion fluids, the warming (and measure the temperature of) the ambulance should improve patient's outcome. As hypothermia is associated with mortality of trauma patients, the control must lead to reduce mortality.

Randomization Due to the use of a global management strategy with combination of several specific interventions and the need for special equipment (heating devices infusion fluids), randomization will be done by investigator center: interventional center (combining the different interventions) and standard management (without modification, except measurements of the patient's and air temperature at inclusion and on arrival at a receiving center.

In this context, it is also crucial that the weather conditions, the characteristics of trauma and patients were similar in both groups. Also, 12 investigation centers will be classified based on annual local average temperatures.

Main collected data Demographics and morphological traits (age, sex, body weight, and height of the victim), the nature and circumstances of the accident (date, time, place), the victim's presentation on mobile intensive care unit (MICU) arrival (trapped or not, seated or lying down, on the ground, unclothed, wet, or covered by a blanket, environmental conditions, clinical factors, and care provided.

Environmental conditions included air (indoors or outdoors) temperature, and rain at the site of the accident as well as mobile intensive care unit temperature.

Clinical factors included: the site and nature of the lesions (fracture, wound, contusion), heart rate, the Revised Trauma Score (RTS) (Glasgow Coma Score (GCS) + systolic blood pressure + respiratory rate), oxygen saturation or oxygen delivery, and tympanic temperature.

Whenever applicable: vascular filling (infusion fluid temperature and volumes), catecholamine and morphine administration, any other drugs (with doses), orotracheal intubation.

Times from the accident to MICU arrival and from MICU arrival to hospital admission.

Statistical analysis Primary endpoint: rate of patients arriving at the hospital with a temperature <35°C. These data will be analyzed by model of multi-level logistic regression to again consider the cluster design of the study. A secondary analysis will enter the model known a priori factors that may affect hypothermia. The parameters corresponding to the secondary objectives will be entered in a model of logistic regression multivariate thereby specifically test their effect on the criteria studied.

Secondary endpoints: Binary secondary endpoints will be analyzed by model of multi-level logistic regression. Quantitative secondary endpoints will be analyzed by mixed model ANCOVA introducing randomness in the center. The variables may be processed before analysis for non-Gaussian distribution. In case of failure of the normalizing transformation, exact procedure may be used.

Number of patients to include The calculation of the sample size was based on our previous study.* The incidence of hypothermia on arrival at the hospital was 14%. By selecting high-risk patients, the investigators expect an incidence of about 20%. The objective is to achieve a reduction of one third of hypothermia (i.e. from 20 to 13 %). Using a two-tailed test at α risk of 0.05 and 1 - beta 0.8, the calculation of required number of patients is 440 per group. Assuming a moderate inflation factor of about 1.35 related to the cluster randomization (our experience shows that intra-cluster correlation coefficients are low) the total number of patients per group will be 600 patients.

A total of N = 1,200 patients for the study.

Inclusion criteria

• Patient with trauma (> 18 years)
• Pre-hospital management by MICU
• Scheduled transfer to a receiving center by a MICU
• And at least one of the following criteria :

• Ambient temperature on the field < 18°C
• Body temperature <35°C on MICU arrival
• A Glasgow score < 15 on MICU arrival
• Systolic blood pressure < 100 mm Hg on MICU arrival

Exclusion criteria

• Body temperature <31°C or >38°C

• Cardiac arrest before MICU arrival
• Bilateral ear bleeding preventing continuous monitoring of tympanic temperature