Strengths, weaknesses and limitations of the study
shock, cardiovascular diseases, ’, traumatic brain injury, analgesia/anaesthesia, injuries, heat loss
HEAT, SHOCK, FIRE, CARDIOVASCULAR DISEASES
Conducting randomised trials in prehospital emergency medicine is difficult and often limited by patients’ inability to give consent and high dynamics. Therefore, retrospective studies are often used. An alternative can be simulations under standardised conditions, as in the present case. The studies described here are randomised, experimental, prospective studies with healthy volunteers. In the present studies, all procedures of the experiments were standardised and strictly adhered to. Due to the crossover design of the two studies, a high statistical comparability could be achieved with a relatively small number of volunteers.Another strength of the studies is the simultaneous assessment of objective parameters such as the change in total body heat and subjective assessments of the awake subjects. However, such a study design with volunteers requires that the subjects could not be blinded. Moreover, only the potential effects of the warming methods can be presented without showing that this is also feasible and will take place in reality. Furthermore, laboratory conditions differ from the real conditions at an accident site, as there environmental conditions such as wind strength, humidity, weather conditions such as rain or snow are not standardised. The clothing chosen for the test persons also was less insulating than that worn by entrapped victims in winter. However, this clothing was deliberately chosen in order to achieve the highest possible heat loss in the volunteers. This might also reflect reality to the same degree because the clothing can be destroyed in the course of traffic accidents, is removed by the rescue service personnel for medical treatment before the fire service arrives, or because of the heater in the car passengers will wear only thin clothes.Another limitation of the study is that the floodlight may often not be directed directly to the entrapped victim as in our volunteer study, thus the poor effect in this study is overestimated compared to real life settings. Furthermore, it is possible, that existing cardiovascular diseases of our volunteers may have had the same influence on the results of the study. We excluded persons with cardiovascular medications to reduce this possible influence. In addition, by choosing a cross over design of the warming methods the potential influence if cardiovascular diseases on our results were further reduced.Another possible limitation of the study is that we did not exclude underweight volunteers with a body mass index below 18.5 kg/m². In fact, we had only one volunteer with a body mass index below 18.5 kg/m². This may have biased our results. However, in using a crossover design between the study arms, the influence should be small.Pathophysiological consequences on the patient’s heat balance due to severe injuries, shock, traumatic brain injury and the invasive measures required for medical care (analgesia/anaesthesia [