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Comparison of three different prehospital wrapping methods for preventing hypothermia--a crossover study in humans.

Thomassen Ø, Færevik H, Østerås Ø, Sunde GA, Zakariassen E, Sandsund M, Heltne JK, Brattebø G - Scand J Trauma Resusc Emerg Med (2011)

Bottom Line: Skin temperature was significantly higher 15 minutes after wrapping using Hibler's method compared with wrapping with ambulance blankets / quilts or bubble wrap.The subjects reported more shivering, they felt colder, were more uncomfortable, and had an increased heat production when using bubble wrap compared with the other two methods.Bubble wrap was the least effective insulating method, and seemed to require significantly higher heat production to compensate for increased heat loss.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Anaesthesia & Intensive Care, Haukeland University Hospital, Bergen, Norway. oyvind.thomassen2@helse-bergen.no

ABSTRACT

Background: Accidental hypothermia increases mortality and morbidity in trauma patients. Various methods for insulating and wrapping hypothermic patients are used worldwide. The aim of this study was to compare the thermal insulating effects and comfort of bubble wrap, ambulance blankets / quilts, and Hibler's method, a low-cost method combining a plastic outer layer with an insulating layer.

Methods: Eight volunteers were dressed in moistened clothing, exposed to a cold and windy environment then wrapped using one of the three different insulation methods in random order on three different days. They were rested quietly on their back for 60 minutes in a cold climatic chamber. Skin temperature, rectal temperature, oxygen consumption were measured, and metabolic heat production was calculated. A questionnaire was used for a subjective evaluation of comfort, thermal sensation, and shivering.

Results: Skin temperature was significantly higher 15 minutes after wrapping using Hibler's method compared with wrapping with ambulance blankets / quilts or bubble wrap. There were no differences in core temperature between the three insulating methods. The subjects reported more shivering, they felt colder, were more uncomfortable, and had an increased heat production when using bubble wrap compared with the other two methods. Hibler's method was the volunteers preferred method for preventing hypothermia. Bubble wrap was the least effective insulating method, and seemed to require significantly higher heat production to compensate for increased heat loss.

Conclusions: This study demonstrated that a combination of vapour tight layer and an additional dry insulating layer (Hibler's method) is the most efficient wrapping method to prevent heat loss, as shown by increased skin temperatures, lower metabolic rate and better thermal comfort. This should then be the method of choice when wrapping a wet patient at risk of developing hypothermia in prehospital environments.

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Wrapping methods. The three different methods of wrapping the subjects
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Figure 1: Wrapping methods. The three different methods of wrapping the subjects

Mentions: The thermal properties of different ensembles are determined by their ability to reduce heat exchange through dry and evaporative resistance. Under dry conditions, the insulating capacity is proportional to the thickness of the insulation, while the evaporative resistance becomes more important under wet conditions e.g when patients are wearing wet clothing. The dry insulation values of a range of different insulation materials and methods have been determined by thermal manikins [13], but the effect of wet clothing will significantly increase the evaporative heat loss. To our knowledge, no previous studies have verified the impact of different thermal insulation and evaporative resistance on thermoregulation and body core temperature in humans. Hence, the aim of this study was to compare the thermal insulating effects and comfort of BW and ABQ. We also wanted to compare these results with the so-called Hibler's method (HM), which is a low-cost method combining plastic with an insulation layer (Figure 1). We hypothesised that a combination of a vapour thight layer and a dry insulating layer (HM) is the most efficient in preventing hypothermia when subjects are wearing wet clothing. To evaluate this we measured body temperatures, shivering response and thermal comfort in healthy subjects wearing wet clothing when exposed to a cold anc windy environment.


Comparison of three different prehospital wrapping methods for preventing hypothermia--a crossover study in humans.

Thomassen Ø, Færevik H, Østerås Ø, Sunde GA, Zakariassen E, Sandsund M, Heltne JK, Brattebø G - Scand J Trauma Resusc Emerg Med (2011)

Wrapping methods. The three different methods of wrapping the subjects
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3142217&req=5

Figure 1: Wrapping methods. The three different methods of wrapping the subjects
Mentions: The thermal properties of different ensembles are determined by their ability to reduce heat exchange through dry and evaporative resistance. Under dry conditions, the insulating capacity is proportional to the thickness of the insulation, while the evaporative resistance becomes more important under wet conditions e.g when patients are wearing wet clothing. The dry insulation values of a range of different insulation materials and methods have been determined by thermal manikins [13], but the effect of wet clothing will significantly increase the evaporative heat loss. To our knowledge, no previous studies have verified the impact of different thermal insulation and evaporative resistance on thermoregulation and body core temperature in humans. Hence, the aim of this study was to compare the thermal insulating effects and comfort of BW and ABQ. We also wanted to compare these results with the so-called Hibler's method (HM), which is a low-cost method combining plastic with an insulation layer (Figure 1). We hypothesised that a combination of a vapour thight layer and a dry insulating layer (HM) is the most efficient in preventing hypothermia when subjects are wearing wet clothing. To evaluate this we measured body temperatures, shivering response and thermal comfort in healthy subjects wearing wet clothing when exposed to a cold anc windy environment.

Bottom Line: Skin temperature was significantly higher 15 minutes after wrapping using Hibler's method compared with wrapping with ambulance blankets / quilts or bubble wrap.The subjects reported more shivering, they felt colder, were more uncomfortable, and had an increased heat production when using bubble wrap compared with the other two methods.Bubble wrap was the least effective insulating method, and seemed to require significantly higher heat production to compensate for increased heat loss.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Anaesthesia & Intensive Care, Haukeland University Hospital, Bergen, Norway. oyvind.thomassen2@helse-bergen.no

ABSTRACT

Background: Accidental hypothermia increases mortality and morbidity in trauma patients. Various methods for insulating and wrapping hypothermic patients are used worldwide. The aim of this study was to compare the thermal insulating effects and comfort of bubble wrap, ambulance blankets / quilts, and Hibler's method, a low-cost method combining a plastic outer layer with an insulating layer.

Methods: Eight volunteers were dressed in moistened clothing, exposed to a cold and windy environment then wrapped using one of the three different insulation methods in random order on three different days. They were rested quietly on their back for 60 minutes in a cold climatic chamber. Skin temperature, rectal temperature, oxygen consumption were measured, and metabolic heat production was calculated. A questionnaire was used for a subjective evaluation of comfort, thermal sensation, and shivering.

Results: Skin temperature was significantly higher 15 minutes after wrapping using Hibler's method compared with wrapping with ambulance blankets / quilts or bubble wrap. There were no differences in core temperature between the three insulating methods. The subjects reported more shivering, they felt colder, were more uncomfortable, and had an increased heat production when using bubble wrap compared with the other two methods. Hibler's method was the volunteers preferred method for preventing hypothermia. Bubble wrap was the least effective insulating method, and seemed to require significantly higher heat production to compensate for increased heat loss.

Conclusions: This study demonstrated that a combination of vapour tight layer and an additional dry insulating layer (Hibler's method) is the most efficient wrapping method to prevent heat loss, as shown by increased skin temperatures, lower metabolic rate and better thermal comfort. This should then be the method of choice when wrapping a wet patient at risk of developing hypothermia in prehospital environments.

Show MeSH
Related in: MedlinePlus