Active Warming in Prehospital Trauma Care

The Effect of Active Warming in Prehospital Trauma Care During Road and Air Ambulance Transportation - a Clinical Randomized Trial

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.

Study Overview

• Status: Completed
• Conditions: Thermal Comfort; Body Core Temperature
• Intervention / Treatment: Device: Additional active warming

• Study Type: Interventional
• Enrollment (Actual): 48
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Sweden
  • Umeå, Sweden, 901 85
    • Department of Surgery and Perioperative Sciences, Umeå University

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

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.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Passive warming with additional active warming	Device: Additional active warming; Chemical heat pad applied to the upper torso
No Intervention: Passive warming

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Time Frame
Body core temperature	From initial assessment upon arrival of EMS crew until second assessment about 30 minutes later.
Cold discomfort	From initial assessment upon arrival of EMS crew until second assessment about 30 minutes later.

Collaborators and Investigators

• Sponsor: Umeå University
• Collaborators: Ministry of Health and Social Affairs, Sweden
• Investigators: Principal Investigator: Ulf Björnstig, MD, PhD, Umea University

Publications and helpful links

General Publications

• Lundgren P, Henriksson O, Naredi P, Bjornstig U. The effect of active warming in prehospital trauma care during road and air ambulance transportation - a clinical randomized trial. Scand J Trauma Resusc Emerg Med. 2011 Oct 21;19:59. doi: 10.1186/1757-7241-19-59.

Study record dates

Study Major Dates

• Study Start: December 1, 2007
• Primary Completion (Actual): May 1, 2010
• Study Completion (Actual): May 1, 2010

Study Registration Dates

• First Submitted: July 18, 2011
• First Submitted That Met QC Criteria: July 21, 2011
• First Posted (Estimate): July 22, 2011

Study Record Updates

• Last Update Posted (Estimate): July 22, 2011
• Last Update Submitted That Met QC Criteria: July 21, 2011
• Last Verified: July 1, 2011

More Information

Terms related to this study

• Keywords: Hypothermia, body temperature regulation,thermal comfort, active warming, passive warming, prehospital trauma care
• Additional Relevant MeSH Terms: Wounds and Injuries
• Other Study ID Numbers: jpl1