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Active Warming in Prehospital Trauma Care

This study has been completed.
Ministry of Health and Social Affairs, Sweden
Information provided by:
Umeå University Identifier:
First received: July 18, 2011
Last updated: July 21, 2011
Last verified: July 2011

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.

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.

Mean core temperatures increased from 35.1°C (95% CI; 34.7-35.5 °C) to 36.0°C (95% CI; 35.7-36.3 °C) (p<0.05) in patients assigned to passive warming only (n=22) and from 35.6°C (95% CI; 35.2-36.0 °C) to 36.4°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).

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 reduce the cold induced stress response.

Condition Intervention
Body Core Temperature
Thermal Comfort
Device: Additional active warming

Study Type: Interventional
Study Design: Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Open Label
Primary Purpose: Prevention
Official Title: The Effect of Active Warming in Prehospital Trauma Care During Road and Air Ambulance Transportation - a Clinical Randomized Trial

Resource links provided by NLM:

Further study details as provided by Umeå University:

Primary Outcome Measures:
  • Body core temperature [ Time Frame: From initial assessment upon arrival of EMS crew until second assessment about 30 minutes later. ]
  • Cold discomfort [ Time Frame: From initial assessment upon arrival of EMS crew until second assessment about 30 minutes later. ]

Enrollment: 48
Study Start Date: December 2007
Study Completion Date: May 2010
Primary Completion Date: May 2010 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Active Comparator: Passive warming with additional active warming Device: Additional active warming
Chemical heat pad applied to the upper torso
No Intervention: Passive warming


Ages Eligible for Study:   18 Years and older   (Adult, Senior)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No

Inclusion Criteria:

  • Subjects were sequential trauma patients, age ≥ 18 years, who had sustained an injury outdoors and were transported by one of the participating EMS units.

Exclusion Criteria:

  • Patients were excluded if initial level of consciousness was affected, (Glasgow Coma Scale < 15), if they required prehospital CPR or if duration of transportation was expected to be shorter than 10 minutes.
  • As the aim of the study was to investigate the effect of active warming intervention in cold stressed patients, those patients who had already received active warming or had been taken indoors for more than 10 minutes before EMS unit arrival or had an initial cold discomfort rating ≤ 2 were also excluded.
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Please refer to this study by its identifier: NCT01400152

Department of Surgery and Perioperative Sciences, Umeå University
Umeå, Sweden, 901 85
Sponsors and Collaborators
Umeå University
Ministry of Health and Social Affairs, Sweden
Principal Investigator: Ulf Björnstig, MD, PhD Umeå University
  More Information

Publications automatically indexed to this study by Identifier (NCT Number):
Responsible Party: Ulf Björnstig, Umeå University Identifier: NCT01400152     History of Changes
Other Study ID Numbers: jpl1
Study First Received: July 18, 2011
Last Updated: July 21, 2011

Keywords provided by Umeå University:
Hypothermia, body temperature regulation,thermal comfort, active warming, passive warming, prehospital trauma care processed this record on May 25, 2017