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Protection Against Cold in Prehospital Care—Thermal Insulation Properties of Blankets and Rescue Bags in Different Wind Conditions

Published online by Cambridge University Press:  28 June 2012

Otto Henriksson ,
J. Peter Lundgren ,
Kalev Kuklane ,
Ingvar Holmér  and
Ulf Bjornstig
Otto Henriksson*
Affiliation:
Division of Surgery, Department of Surgery and Perioperative Sciences, Umea University, Sweden
J. Peter Lundgren
Affiliation:
Division of Surgery, Department of Surgery and Perioperative Sciences, Umea University, Sweden
Kalev Kuklane
Affiliation:
Thermal Environment Laboratory, Department of Design Sciences, Faculty of Engineering, Lund University, Sweden
Ingvar Holmér
Affiliation:
Thermal Environment Laboratory, Department of Design Sciences, Faculty of Engineering, Lund University, Sweden
Ulf Bjornstig
Affiliation:
Thermal Environment Laboratory, Department of Design Sciences, Faculty of Engineering, Lund University, Sweden
*
Division of Surgery, Department of Surgery and Perioperative Sciences, Umea University, SE-90185, Umea, Sweden, E-mail: otto.henriksson@hotmail.com
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Abstract

Introduction:

In a cold, wet, or windy environment, cold exposure can be considerable for an injured or ill person. The subsequent autonomous stress response initially will increase circulatory and respiratory demands, and as body core temperature declines, the patient's condition might deteriorate. Therefore, the application of adequate insulation to reduce cold exposure and prevent body core cooling is an important part of prehospital primary care, but recommendations for what should be used in the field mostly depend on tradition and experience, not on scientific evidence.

Objective:

The objective of this study was to evaluate the thermal insulation properties in different wind conditions of 12 different blankets and rescue bags commonly used by prehospital rescue and ambulance services.

Methods:

The thermal manikin and the selected insulation ensembles were setup inside a climatic chamber in accordance to the modified European Standard for assessing requirements of sleeping bags. Fans were adjusted to provide low (< 0.5 m/s), moderate (2–3 m/s) and high (8–9 m/s) wind condi-tions. During steady state thermal transfer, the total resultant insulation value, Itr (m2 °C/Wclo; where °C = degrees Celcius, and W = watts), was calculated from ambient air temperature (°C), manikin surface temperature (°C), and heat flux (W/m2).

Results:

In the low wind condition, thermal insulation of the evaluated ensembles correlated to thickness of the ensembles, ranging from 2.0 to 6.0 clo (1 clo = 0.155 m2 °C/W), except for the reflective metallic foil blankets that had higher values than expected. In moderate and high wind conditions, thermal insulation was best preserved for ensembles that were windproof and resistant to the compressive effect of the wind, with insulation reductions down to about 60–80% of the original insulation capacity, whereas wind permeable and/or lighter materials were reduced down to about 30–50% of original insulation capacity.

Conclusions:

The evaluated insulation ensembles might all be used for prehospital protection against cold, either as single blankets or in multiple layer combinations, depending on ambient temperatures. However, with extended outdoor, on-scene durations, such as during prolonged extrications or in mul-tiple casualty situations, the results of this study emphasize the importance of using a windproof and compression resistant outer ensemble to maintain adequate insulation capacity.

Keywords

body temperature regulationcoldemergency medical serviceshypothermiathermal insulationthermal manikinwind
Type
Original Research
Information
Prehospital and Disaster Medicine , Volume 24 , Issue 5 , October 2009 , pp. 408 - 415
Copyright
Copyright © World Association for Disaster and Emergency Medicine 2009

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