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Mydske S, Brattebø G, Østerås Ø, Wiggen Ø, Assmus J, Thomassen Ø. Effect of a vapor barrier in combination with active external rewarming for cold-stressed patients in a prehospital setting: a randomized, crossover field study. Scand J Trauma Resusc Emerg Med 2024; 32:35. [PMID: 38664809 PMCID: PMC11044347 DOI: 10.1186/s13049-024-01204-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Accepted: 04/04/2024] [Indexed: 04/28/2024] Open
Abstract
BACKGROUND Use of a vapor barrier in the prehospital care of cold-stressed or hypothermic patients aims to reduce evaporative heat loss and accelerate rewarming. The application of a vapor barrier is recommended in various guidelines, along with both insulating and wind/waterproof layers and an active external rewarming device; however, evidence of its effect is limited. This study aimed to investigate the effect of using a vapor barrier as the inner layer in the recommended "burrito" model for wrapping hypothermic patients in the field. METHODS In this, randomized, crossover field study, 16 healthy volunteers wearing wet clothing were subjected to a 30-minute cooling period in a snow chamber before being wrapped in a model including an active heating source either with (intervention) or without (control) a vapor barrier. The mean skin temperature, core temperature, and humidity in the model were measured, and the shivering intensity and thermal comfort were assessed using a subjective questionnaire. The mean skin temperature was the primary outcome, whereas humidity and thermal comfort were the secondary outcomes. Primary outcome data were analyzed using analysis of covariance (ANCOVA). RESULTS We found a higher mean skin temperature in the intervention group than in the control group after approximately 25 min (p < 0.05), and this difference persisted for the rest of the 60-minute study period. The largest difference in mean skin temperature was 0.93 °C after 60 min. Humidity levels outside the vapor barrier were significantly higher in the control group than in the intervention group after 5 min. There were no significant differences in subjective comfort. However, there was a consistent trend toward increased comfort in the intervention group compared with the control group. CONCLUSIONS The use of a vapor barrier as the innermost layer in combination with an active external heat source leads to higher mean skin rewarming rates in patients wearing wet clothing who are at risk of accidental hypothermia. TRIAL REGISTRATION ClinicalTrials.gov identifier: NCT05779722.
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Affiliation(s)
- Sigurd Mydske
- Department of Anaesthesia & Intensive Care, Haukeland University Hospital, Bergen, Norway.
- Mountain Medicine Research Group, The Norwegian Air Ambulance Foundation, Bergen, Norway.
- Department of Clinical Medicine, University of Bergen, Bergen, Norway.
| | - Guttorm Brattebø
- Department of Anaesthesia & Intensive Care, Haukeland University Hospital, Bergen, Norway
- Mountain Medicine Research Group, The Norwegian Air Ambulance Foundation, Bergen, Norway
- Department of Clinical Medicine, University of Bergen, Bergen, Norway
- Norwegian National Advisory Unit on Emergency Medical Communication, Haukeland University Hospital, Bergen, Norway
| | - Øyvind Østerås
- Department of Anaesthesia & Intensive Care, Haukeland University Hospital, Bergen, Norway
- Mountain Medicine Research Group, The Norwegian Air Ambulance Foundation, Bergen, Norway
| | - Øystein Wiggen
- Mountain Medicine Research Group, The Norwegian Air Ambulance Foundation, Bergen, Norway
- SINTEF Technology and Society, Preventive Health Research, Trondheim, Norway
| | - Jörg Assmus
- Department of Anaesthesia & Intensive Care, Haukeland University Hospital, Bergen, Norway
- Mountain Medicine Research Group, The Norwegian Air Ambulance Foundation, Bergen, Norway
- Department of Clinical Medicine, University of Bergen, Bergen, Norway
| | - Øyvind Thomassen
- Department of Anaesthesia & Intensive Care, Haukeland University Hospital, Bergen, Norway
- Mountain Medicine Research Group, The Norwegian Air Ambulance Foundation, Bergen, Norway
- Department of Clinical Medicine, University of Bergen, Bergen, Norway
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Hagen LT, Brattebø G, Dipl-Math JA, Wiggen Ø, Østerås Ø, Mydske S, Thomassen Ø. Effect of wet clothing removal on skin temperature in subjects exposed to cold and wrapped in a vapor barrier: a human, randomized, crossover field study. BMC Emerg Med 2024; 24:18. [PMID: 38273259 PMCID: PMC10809790 DOI: 10.1186/s12873-024-00937-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Accepted: 01/17/2024] [Indexed: 01/27/2024] Open
Abstract
BACKGROUND Prehospital care for cold-stressed and hypothermic patients focuses on effective insulation and rewarming. When encountering patients wearing wet clothing, rescuers can either remove the wet clothing before isolating the patient or isolate the patient using a vapor barrier. Wet clothing removal increases skin exposure but avoids the need to heat the wet clothing during rewarming. Leaving wet clothing on will avoid skin exposure but is likely to increase heat loss during rewarming. This study aimed to evaluate the effect of wet clothing removal compared to containing the moisture using a vapor barrier on skin temperature in a prehospital setting. METHODS This randomized crossover experimental field study was conducted in a snow cave in Hemsedal, Norway. After an initial cooling phase of 30 min while wearing wet clothes, the participants were subjected to one of two rewarming scenarios: (1) wet clothing removal and wrapping in a vapor barrier, insulating blankets, and windproof outer shell (dry group) or (2) wrapping in a vapor barrier, insulating blankets, and windproof outer shell (wet group). The mean skin temperature was the primary outcome whereas subjective scores for both thermal comfort and degree of shivering were secondary outcomes. Primary outcome data were analyzed using the analysis of covariance (ANCOVA). RESULTS After an initial decrease in temperature during the exposure phase, the dry group had a higher mean skin temperature compared to the wet group after only 2 min. The skin-rewarming rate was highest in the initial rewarming stages for both groups, but increased in the dry group as compared to the wet group in the first 10 min. Return to baseline temperature occurred significantly faster in the dry group (mean 12.5 min [dry] vs. 28.1 min [wet]). No intergroup differences in the subjective thermal comfort or shivering were observed. CONCLUSION Removal of wet clothing in combination with a vapor barrier increases skin rewarming rate compared to encasing the wet clothing in a vapor barrier, in mild cold and environments without wind. TRIAL REGISTRATION ClinicalTrials.gov ID NCT05996757, retrospectively registered 18/08/2023.
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Affiliation(s)
- Linn Therese Hagen
- Department of Anaesthesia and Intensive Care, Haukeland University Hospital, P.O. Box 1400, Bergen, 5021, Norway.
- Faculty of health sciences, University of Stavanger, Stavanger, Norway.
- Mountain Medicine Research Group, The Norwegian Air Ambulance Foundation, Bergen, Norway.
| | - Guttorm Brattebø
- Department of Anaesthesia and Intensive Care, Haukeland University Hospital, P.O. Box 1400, Bergen, 5021, Norway
- Mountain Medicine Research Group, The Norwegian Air Ambulance Foundation, Bergen, Norway
- Department of Clinical Medicine, University of Bergen, Bergen, Norway
| | - Jörg Assmus Dipl-Math
- Mountain Medicine Research Group, The Norwegian Air Ambulance Foundation, Bergen, Norway
- Centre for Clinical Research, Haukeland University Hospital, Bergen, Norway
| | - Øystein Wiggen
- SINTEF Technology and Society, Preventive Health Research, Trondheim, Norway
| | - Øyvind Østerås
- Department of Anaesthesia and Intensive Care, Haukeland University Hospital, P.O. Box 1400, Bergen, 5021, Norway
- Department of Clinical Medicine, University of Bergen, Bergen, Norway
| | - Sigurd Mydske
- Department of Anaesthesia and Intensive Care, Haukeland University Hospital, P.O. Box 1400, Bergen, 5021, Norway
- Mountain Medicine Research Group, The Norwegian Air Ambulance Foundation, Bergen, Norway
- Department of Clinical Medicine, University of Bergen, Bergen, Norway
| | - Øyvind Thomassen
- Department of Anaesthesia and Intensive Care, Haukeland University Hospital, P.O. Box 1400, Bergen, 5021, Norway
- Mountain Medicine Research Group, The Norwegian Air Ambulance Foundation, Bergen, Norway
- Department of Clinical Medicine, University of Bergen, Bergen, Norway
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Mydske S, Haukeland IC, Godø AH, Grytaas MA, Vold JH, Hartwig A. En kvinne i 20-årene med paranoide vrangforestillinger. Tidsskriftet 2022; 142:22-0243. [DOI: 10.4045/tidsskr.22.0243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Wik L, Brattebø G, Østerås Ø, Assmus J, Irusta U, Aramendi E, Mydske S, Skaalhegg T, Christjar Skaiaa S, Thomassen Ø. Physiological effects of providing supplemental air for avalanche victims. A randomised trial. Resuscitation 2022; 172:38-46. [DOI: 10.1016/j.resuscitation.2022.01.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Revised: 12/23/2021] [Accepted: 01/11/2022] [Indexed: 11/28/2022]
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Mydske S, Thomassen Ø. Correction to: Is prehospital use of active external warming dangerous for patients with accidental hypothermia: a systematic review. Scand J Trauma Resusc Emerg Med 2020; 28:105. [PMID: 33106177 PMCID: PMC7586664 DOI: 10.1186/s13049-020-00802-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Affiliation(s)
- Sigurd Mydske
- Department of Anaesthesia and Intensive Care, Haukeland University Hospital, Bergen, Norway. .,Mountain Medicine Research Group, University of Bergen, Bergen, Norway.
| | - Øyvind Thomassen
- Department of Anaesthesia and Intensive Care, Haukeland University Hospital, Bergen, Norway.,Mountain Medicine Research Group, University of Bergen, Bergen, Norway.,Department of Research and Development, Norwegian Air Ambulance Foundation, Oslo, Norway
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Mydske S, Thomassen Ø. Is prehospital use of active external warming dangerous for patients with accidental hypothermia: a systematic review. Scand J Trauma Resusc Emerg Med 2020; 28:77. [PMID: 32778153 PMCID: PMC7419182 DOI: 10.1186/s13049-020-00773-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Accepted: 07/29/2020] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND Optimal prehospital management and treatment of patients with accidental hypothermia is a matter of frequent debate, with controversies usually revolving around the subject of rewarming. The rule of thumb in primary emergency care and first aid for patients with accidental hypothermia has traditionally been to be refrain from prehospital active rewarming and to focus on preventing further heat loss. The potential danger of active external rewarming in a prehospital setting has previously been generally accepted among the emergency medicine community based on a fear of potential complications, such as "afterdrop", "rewarming syndrome", and "circum-rescue collapse". This has led to a reluctancy from health care providers to provide patients with active external rewarming outside the hospital. Different theories and hypotheses exist for these physiological phenomena, but the scientific evidence is limited. The research question is whether the prehospital use of active external rewarming is dangerous for patients with accidental hypothermia. This systematic review intends to describe the acute unfavourable adverse effects of active external rewarming on patients with accidental hypothermia. METHODS A literature search of the Cochrane Library, MEDLINE, EMBASE, the Cumulative Index to Nursing and Allied Health Literature (CINAHL], and SveMed+ was carried out, and all articles were screened for eligibility. All article formats were included. RESULTS Two thousand three hundred two articles were screened, and eight articles met our search criteria. Three articles were case reports or case series, one was a prospective study, two were retrospective studies, one article was a literature review, and one article was a war report from the Napoleonic Wars. CONCLUSIONS One of the main findings in this article was the poor scientific quality and the low number of articles meeting our inclusion criteria. When conducting this review, we found no scientific evidence of acceptable quality to prove that the use of active external rewarming is dangerous for patients with accidental hypothermia in a prehospital setting. We found several articles claiming that active external rewarming is dangerous, but most of them do not cite references or provide evidence.
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Affiliation(s)
- Sigurd Mydske
- Department of Anaesthesia and Intensive Care, Haukeland University Hospital, Bergen, Norway.
- Mountain Medicine Research Group, University of Bergen, Bergen, Norway.
| | - Øyvind Thomassen
- Department of Anaesthesia and Intensive Care, Haukeland University Hospital, Bergen, Norway
- Mountain Medicine Research Group, University of Bergen, Bergen, Norway
- Department of Research and Development, Norwegian Air Ambulance Foundation, Oslo, Norway
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