Clinical Evaluation of Effectiveness of the "Therm'Up" Heating Device

Hypothermia is defi ned as a core temperature below 35°C. Accidental hypothermia occurs when the human body loses more heat than it produces, resulting in a drop in body temperature.

Core body temperature is the standard physiological parameter for diagnosing and classifying the severity of hypothermia. Mild accidental hypothermia is defi ned as a core body temperature between 32 and 35°C, moderate hypothermia as a core temperature between 28 and 32°C, and severe hypothermia as a core temperature \<28°C.

Trauma patients are at high risk of accidental hypothermia (body temperature ≤ 35°C). Hypothermia has signifi cant consequences on human physiology, including the cardiac, pulmonary, neurological, and hemostatic systems.

Hypothermia is of particular concern in trauma patients because it is associated with increased morbidity and mortality. In addition, hypothermia can infl uence blood coagulation by reducing platelet aggregation and increasing fi brinolysis. Three closely related elements: metabolic acidosis, coagulopathy, and hypothermia constitute the "lethal triad" of trauma. The presence of one or more of these elements during the management of a severely traumatized patient increases the risk of early mortality.

The occurrence of shivering in a patient is also an indicator of hypothermia. Shivering can increase oxygen consumption of muscle cells by up to 400%. The goal of prehospital care is to prevent the onset of shivering, making the use of passive warming measures crucial.

In a systematic review, the prevalence of hypothermia in trauma victims on arrival at hospital was found to be high, at 14%.

An observational study conducted by the SMUR (Mobile Emergency and Resuscitation Services) team of eight French hospitals between January 1, 2004 and November 10, 2007, measured the body temperature of 448 patients upon arrival at the hospital. Hypothermia (body temperature ≤ 35°C) was present in 64 of these 448 patients (14%). Optimal patient care can help limit heat loss or hypothermia. It is important to note that the prolonged time required to recover patients after a road accident increases the risk of lasting hypothermia. This hypothermia, linked to the accident, is associated with an increased mortality rate in severely injured patients, which underlines the importance of prehospital efforts to prevent hypothermia.

Prevention of hypothermia in trauma patients in the prehospital care setting is of critical importance. Various devices have been designed to reduce heat loss and/or actively warm patients in a prehospital environment.

Warming strategies are not ideally suited to pre-hospital care due to the complexity of their implementation and their inadequacy to the conditions encountered. Active external systems generate heat transferred to the patient, while passive systems isolate the patient by preventing the dispersion of body heat.

In most cases, passive warming methods are used, such as the use of insulating survival blankets, which still allow the patient to be insulated from the cold. The insulating survival blanket is used in emergency situations to cover a victim and prevent hypothermia. It is an essential product in the event of illness or accident (trauma, fall, etc.), or in the event of a sudden change in temperature, to maintain the victim's body temperature, protect them from the cold and wind and prevent hypothermia. These so-called "isothermal" blankets allow the body temperature to be maintained at around 37°C.

Active external warming is only possible with chemical, electrical methods or warm air blankets, but these are diffi cult to access before arrival at the hospital due to their high cost, their signifi cant environmental impact (single use) and their unsuitability for outdoor use. However, only proactive and early administration of heat can effectively combat hypothermia and its consequences. The use of a heated blanket or better still, a warm air mattress, is much more effective and allows to gain 1 to 2 °C of core temperature per hour. In out-of-hospital and mountain rescue environments, measuring core temperature can guide transport and treatment decisions, although obtaining an accurate value can be difficult.

Developing alternatives to current devices would reduce health risks and allow targeted intervention to control core temperature, thereby preventing or reducing the harmful consequences of hypothermia. This type of innovation would also have the potential to reduce the risks and limitations associated with existing technical procedures. Hence the objective of this clinical investigation to assess the non-inferiority of a new Therm'Up device compared to the survival blanket to prevent hypothermia in trauma patients in prehospital care.