Experimental design and conduct
Trauma, NRS, muscle tremors
COLD
Each study (A and B) was designed in a crossover fashion with a washout period of at least 24 h between the two interventions. Volunteers received both warming methods (interventions) each. The order of the warming methods was randomised by letting the participants drawing lots.Only some of the volunteers where the same in study A and study B.In order to simulate the environmental situation of a traffic accident in a standardised way, a driver’s seat of a passenger car was placed in a 7500 m² cold store at a stable ambient temperature of 3 °C ± 1 °C. The volunteers were placed in the driver’s seat of a passenger car dressed for the test period in a T-shirt, shorts, underwear, stockings and shoes. They were asked to move as little as possible during the experiment.Monitoring was applied before the start of the experiments: ECG, oscillometric blood pressure measurement and peripheral oxygen saturation. Additionally, core body temperature was measured by means of a tympanic contact temperature probe (Tympanic Temperature Probe with Foam, Disposable, 400 Series, GE Healthcare GmbH, Solingen, Germany). This measuring probe was placed in the right auditory canal and pushed forward until the volunteers noticed contact with the eardrum. The ear canal was then covered with cotton wool and a bandage was applied around the head to secure it.These parameters were then continuously monitored and documented using a Propaq EL 104 E monitor (Welch Allyn Limited, Navan, Ireland). In addition, skin temperature was determined every 3 min using the KIRAY 300 infrared thermometer (ELECTRO-MATION GmbH, Hamburg, Germany) at the following skin sites:
Upper arm (medial outside right).Chest (medial approximately 5 cm above the mammillary line).Thigh (medial outer right).Calf (medial right).Occurring muscle tremors were recorded according to the Bedside Shivering Assessment Scale (BSA) (Table 
Bedside shivering assessment scale [Furthermore, the subjective cold perception was determined by means of a numerical rating scale (NRS). To this end, volunteers were asked to describe their respective cold perception on a numeric scale from 0 (pleasant feeling of warmth) to 10 (maximum feeling of cold).In addition, the volunteers were asked about their subjective evaluation of the heating method. The following answers were available for selection:The heating method:Did not have any effect at allWarmed only slightlyWarmed moderatelyWarmed considerablyFor the experiment itself, volunteers were placed on the car seat and the first measurement was started at time 0 min. The experimental set-up was intended to reflect the typical time course of prehospital care. With an average duration of the prehospital time between accident and hospital admission for severely injured patients of roughly 60 min (Trauma Register of the DGU Annual Report 2021, 