In multiple trauma patients accidental hypothermia (i.e. core temperature < 35°C) is more frequent in winter but must be expected at all seasons of the year, even in regions with moderate climate [1]. The incidence of multiple trauma patients admitted with accidental hypothermia is underestimated, but may exceed 30% [1]. The low reporting rate of accidental hypothermia is partly owed to the lack of reliable thermometers for cold environment. The low awareness for accidental hypothermia leads to insufficient insulation and rewarming measures in the pre- and in-hospital setting.

Accidental hypothermia in multiple trauma is an independent risk factor for increased mortality. In a state-wide trauma registry in Pennsylvania (n = 38,520) mortality of multiple trauma patients increased exponentially with the degree of accidental hypothermia at hospital admission. With a core temperature < 32°C at hospital admission mortality approached 50% (Figure 1) [2]. Multiple trauma patients are prone to accidental hypothermia because central and peripheral thermoregulation are inhibited. This may be due to haemorrhage (i.e. underperfusion of thermoregulation centres in the hypothalamus) and reduced or abolished shivering. Vasodilation as a result of peripheral hypoxia with concomitant metabolic acidosis or analgosedation (possibly less pronounced with ketamine) [3, 4].

Keeping the traumatized patient normothermic is of utmost importance. Patients should be thoroughly and timely insulated, cold and excessive infusions avoided, considerate analgesia and sedation provided with the understanding that they may accelerate cooling. In a cold environment changing clothes is not required as long as patients are insulated water-vapour-tight to avoid heat loss through evaporation [5, 6]. Implementation of the available knowledge and equipment is recommended [7]. Rewarming should be commenced as soon and as aggressively as possible. Even though in regular ambulances and transport times of < 1 hour prehospital rewarming may not be feasible, further cooling of the warm body core by the cold body shell can be limited. In prolonged transports with the availability of forced warm air or heating body pads rewarming (1–2°C/h) may be achieved [8].