The effect of active warming in prehospital trauma care during road and air ambulance transportation : a clinical randomized trial

摘要

Background: Prevention and treatment of hypothermia by active warming in prehospital trauma care is recommended but scientifical evidence of its effectiveness in a clinical setting is scarce. The objective of this study was to evaluate the effect of additional active warming during road or air ambulance transportation of trauma patients. Methods: Patients were assigned to either passive warming with blankets or passive warming with blankets with the addition of an active warming intervention using a large chemical heat pad applied to the upper torso. Ear canal temperature, subjective sensation of cold discomfort and vital signs were monitored. Results: Mean core temperatures increased from35.1°C(95% CI; 34.7–35.5 °C) to36.0°C(95% CI; 35.7–36.3 °C) (p<0.05) in patients assigned to passive warming only (n=22) and from35.6°C(95% CI; 35.2–36.0 °C) to36.4°C(95% CI; 36.1–36.7°C) (p<0.05) in patients assigned to additional active warming (n=26) with no significant differences between the groups. Cold discomfort decreased in 2/3 of patients assigned to passive warming only and in all patients assigned to additional active warming, the difference in cold discomfort change being statistically significant (p<0.05). Patients assigned to additional active warming also presented a statistically significant decrease in heart rate and respiratory frequency (p<0.05). Conclusions: In mildly hypothermic trauma patients, with preserved shivering capacity, adequate passive warming is an effective treatment to establish a slow rewarming rate and to reduce cold discomfort during prehospital transportation. However, the addition of active warming using a chemical heat pad applied to the torso will significantly improve thermal comfort even further and might also reduce the cold induced stress response.