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Protection against Cold in Prehospital Care: Evaporative Heat Loss Reduction by Wet Clothing Removal or the Addition of a Vapor Barrier—A Thermal Manikin Study

Published online by Cambridge University Press:  23 March 2012

Otto Henriksson ,
Peter Lundgren ,
Kalev Kuklane ,
Ingvar Holmér ,
Peter Naredi  and
Ulf Bjornstig
Otto Henriksson*
Affiliation:
Division of Surgery, Department of Surgery and Perioperative Sciences, Umea University, Umea, Sweden
Peter Lundgren
Affiliation:
Division of Surgery, Department of Surgery and Perioperative Sciences, Umea University, Umea, Sweden
Kalev Kuklane
Affiliation:
Thermal Environment Laboratory, Department of Design Sciences, Faculty of Engineering, Lund University, Lund, Sweden
Ingvar Holmér
Affiliation:
Thermal Environment Laboratory, Department of Design Sciences, Faculty of Engineering, Lund University, Lund, Sweden
Peter Naredi
Affiliation:
Division of Surgery, Department of Surgery and Perioperative Sciences, Umea University, Umea, Sweden
Ulf Bjornstig
Affiliation:
Division of Surgery, Department of Surgery and Perioperative Sciences, Umea University, Umea, Sweden
*
Correspondence: Otto Henriksson, MD Division of Surgery Department of Surgery and Perioperative Sciences Umea UniversitySE-901 85 Umea, Sweden E-mail: [email protected]
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Abstract

Introduction: In the prehospital care of a cold and wet person, early application of adequate insulation is of utmost importance to reduce cold stress, limit body core cooling, and prevent deterioration of the patient’s condition. Most prehospital guidelines on protection against cold recommend the removal of wet clothing prior to insulation, and some also recommend the use of a waterproof vapor barrier to reduce evaporative heat loss. However, there is little scientific evidence of the effectiveness of these measures.

Objective: Using a thermal manikin with wet clothing, this study was conducted to determine the effect of wet clothing removal or the addition of a vapor barrier on thermal insulation and evaporative heat loss using different amounts of insulation in both warm and cold ambient conditions.

Methods: A thermal manikin dressed in wet clothing was set up in accordance with the European Standard for assessing requirements of sleeping bags, modified for wet heat loss determination, and the climatic chamber was set to -15 degrees Celsius (°C) for cold conditions and +10°C for warm conditions. Three different insulation ensembles, one, two or seven woollen blankets, were chosen to provide different levels of insulation. Five different test conditions were evaluated for all three levels of insulation ensembles: (1) dry underwear; (2) dry underwear with a vapor barrier; (3) wet underwear; (4) wet underwear with a vapor barrier; and (5) no underwear. Dry and wet heat loss and thermal resistance were determined from continuous monitoring of ambient air temperature, manikin surface temperature, heat flux and evaporative mass loss rate.

Results: Independent of insulation thickness or ambient temperature, the removal of wet clothing or the addition of a vapor barrier resulted in a reduction in total heat loss of 19-42%. The absolute heat loss reduction was greater, however, and thus clinically more important in cold environments when little insulation is available. A similar reduction in total heat loss was also achieved by increasing the insulation from one to two blankets or from two to seven blankets.

Conclusion: Wet clothing removal or the addition of a vapor barrier effectively reduced evaporative heat loss and might thus be of great importance in prehospital rescue scenarios in cold environments with limited insulation available, such as in mass-casualty situations or during protracted evacuations in harsh conditions.

Keywords

Emergency Medical Servicesheat losshypothermiathermal insulationthermal manikin
Type
Original Research
Information
Prehospital and Disaster Medicine , Volume 27 , Issue 1 , February 2012 , pp. 53 - 58
Copyright
Copyright Henriksson © World Association for Disaster and Emergency Medicine 2012

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