| 1. |
- Aléx, Jonas, et al.
(författare)
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Being cold when injured in a cold environment : patients' experiences
- 2013
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Ingår i: International Emergency Nursing. - : Elsevier BV. - 1755-599X .- 1878-013X. ; 21:1, s. 42-49
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Tidskriftsartikel (refereegranskat)abstract
- Background: Patients in prehospital care, irrespective of diseases or trauma might experience thermal discomfort because of a cold environment and are at risk for decreasing body temperature which can increase both morbidity and mortality.Objective: To explore patients' experiences of being cold when injured in a cold environment.Method: Twenty persons who had been injured in a cold environment in northern Sweden were interviewed. Active heat supply was given to 13 of them and seven had passive heat supply. The participants were asked to narrate their individual experience of cold and the pre- and post-injury event, until arrival at the emergency department. The interviews were transcribed verbatim, then analyzed with qualitative content analysis.Results: Patients described that they suffered more from the cold than because of the pain from the injury. Patients who received active heat supply experienced it in a positive way. Two categories were formulated: Enduring suffering and Relief of suffering.Conclusion: Thermal discomfort became the largest problem independent of the severity of the injuries. We recommend the use of active heat supply to reduce the negative experiences of thermal discomfort when a person is injured in a cold environment.
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| 2. |
- Henriksson, Otto, 1976-, et al.
(författare)
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Protection against cold in prehospital care : evaporative heat loss reduction by wet clothing removal or the addition of a vapour barrier - a thermal manikin study
- 2012
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Ingår i: Prehospital and Disaster Medicine. - 1049-023X .- 1945-1938. ; 26:6, s. 1-6
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Tidskriftsartikel (refereegranskat)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.
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| 3. |
- Henriksson, Otto, 1976-
(författare)
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Protection against cold in prehospital trauma care
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background: Protection against cold is vitally important in prehospital trauma care to reduce heat loss and prevent body core cooling. Objectives: Evaluate the effect on cold stress and thermoregulation in volunteer subjects byutilising additional insulation on a spineboard (I). Determine thermal insulation properties of blankets and rescue bags in different wind conditions (II). Establish the utility of wet clothing removal or the addition of a vapour barrier by determining the effect on heat loss within different levels of insulation in cold and warm ambient temperatures (III) and evaluating the effect on cold stress and thermoregulation in volunteer subjects (IV). Methods: Aural canal temperature, sensation of shivering and cold discomfort was evaluated in volunteer subjects, immobilised on non-insulated (n=10) or insulated (n=9) spineboards in cold outdoor conditions (I). A thermal manikin was setup inside a climatic chamber and total resultant thermal insulation for the selected ensembles was determined in low, moderate and high wind conditions (II). Dry and wet heat loss and the effect of wet clothing removal or the addition of a vapour barrier was determined with the thermal manikin dressed in either dry, wet or no clothing; with or without a vapour barrier; and with three different levels of insulation in warm and cold ambient conditions (III). The effect on metabolic rate, oesophageal temperature, skin temperature, body heat storage, heart rate, and cold discomfort by wet clothing removal or the addition of a vapour barrier was evaluated in volunteer subjects (n=8), wearing wet clothing in a cold climatic chamber during four different insulation protocols in a cross-over design (IV). Results: Additional insulation on a spine board rendered a significant reduction of estimated shivering but there was no significant difference in aural canal temperature or cold discomfort (I). In low wind conditions, thermal insulation correlated to thickness of the insulation ensemble. In greater air velocities, thermal insulation was better preserved for ensembles that were windproof and resistant to the compressive effect of the wind (II). Wet clothing removal or the use of a vapour barrier reduced total heat loss by about one fourth in the cold environment and about one third in the warm environment (III). In cold stressed wet subjects, with limited insulation applied, wet clothing removal or the addition of a vapour barrier significantly reduced metabolic rate, increased skin rewarming rate, and improved total body heat storage but there was no significant difference in heart rate or oesophageal temperature cooling rate (IV). Similar effects on heat loss and cold stress was also achieved by increasing the insulation. Cold discomfort was significantly reduced with the addition of a vapour barrier and with an increased insulation but not with wet clothing removal. Conclusions: Additional insulation on a spine board might aid in reducing cold stress inprolonged transportations in a cold environment. In extended on scene durations, the use of a windproof and compression resistant outer cover is crucial to maintain adequate thermal insulation. In a sustained cold environment in which sufficient insulation is not available, wet clothing removal or the use of a vapour barrier might be considerably important reducing heat loss and relieving cold stress.
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| 4. |
- Kuklane, Kalev, et al.
(författare)
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Moisture and clothing layers: effect of ambient temperature on heat loss and insulation
- 2010
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Ingår i: 8I3M : Eighth International Meeting for Manikins and Modeling : Victoria, BC, Canada, August 22-26, 2010 - Eighth International Meeting for Manikins and Modeling : Victoria, BC, Canada, August 22-26, 2010.
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Konferensbidrag (refereegranskat)abstract
- During the latest years the research on the effects of moisture on clothing system has been boosted. New information has revealed phenomena, e.g. “heat pipe” effect with its condensation-evaporation cycle(s) that has not been considered earlier in prediction of physiological reactions or evaluating clothing properties. Considering the material properties, e.g. the evaporative resistance measurements, the tests at homogenous conditions with registration of mass loss would be probably the correct approach. On the other hand, until there is no clear picture where condensation occurs, role of wicking and the probability of re-evaporation in multilayer clothing at different environmental conditions measuring the real heat losses in order to evaluate human thermal responses in realistic test conditions is important. An example of such need is the selection of proper means for protection against cold in prehospital care at accident sites. In this study thermal manikin was tested with wet underwear and wrapped in 1, 2 or 7 layers of woollen rescue blankets at -15 and +10 °C. This paper discusses the issues related to possibility to improve predictions for the cases when other situations, materials or exposure temperatures are involved. A method to quantify “heat pipe” effect was proposed, and for control the calculation of dry insulation from wet tests was applied. The measured apparent insulation, i.e. insulation based on total heat loss in wet conditions, was higher at -15 °C than at + 10 °C. That could be related to higher condensation rate in materials or suppressed evaporation. However, the measured weight loss rate (higher at 15 °C) and accumulation in layers (lower at 15 °C) did not support this conclusion. Effect could partly be related to the lower water pressure gradient between wet clothing at manikin surface and ambient air at +10 (2.5 kPa) than -15 °C (3.0 kPa). In the case of 7 layers the highest accumulation occurred in the layers near body and in the outermost layer while only minimal accumulation of moisture was observed in the middle layers. The total accumulation was divided into ratios for each layer, and expected condensation heat to environment was based on insulation (7 layers, 1/7 of the first and 7/7 of the outer layer leaves the system). When this correction was applied to “heat pipe” effect then the corrected heat loss did lead to insulation values similar to dry tests. The method worked also for 1 and 2 layer systems with highest difference for 1 layer system. The method could be tested more accurately on a sweating cylinder/torso, where layers may be separated in order to avoid wicking or vice versa set to allow it. Using different number of layers, layer thickness and less hygroscopic materials than wool may improve estimation of the “heat pipe” effects.
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| 5. |
- Lundgren, Peter, et al.
(författare)
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The effect of active warming in prehospital trauma care during road and air ambulance transportation : a clinical randomized trial
- 2011
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Ingår i: Scandinavian Journal of Trauma, Resuscitation and Emergency Medicine. - : BioMed Central. - 1757-7241. ; 19:59
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Tidskriftsartikel (refereegranskat)abstract
- Background: 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. Methods: 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. Results: Mean core temperatures increased from35.1°C(95% CI; 34.7–35.5 °C) to36.0°C(95% CI; 35.7–36.3 °C) (p<0.05) in patients assigned to passive warming only (n=22) and from35.6°C(95% CI; 35.2–36.0 °C) to36.4°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). Conclusions: 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 might also reduce the cold induced stress response.
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| 6. |
- Lundgren, Peter, 1977-, et al.
(författare)
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Validity and reliability of the Cold Discomfort Scale : a subjective judgement scale for the assessment of patient thermal state in a cold environment.
- 2014
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Ingår i: Journal of clinical monitoring and computing. - : Springer Science and Business Media LLC. - 1387-1307 .- 1573-2614. ; 28:3, s. 287-291
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Tidskriftsartikel (refereegranskat)abstract
- Complementary measures for the assessment of patient thermoregulatory state, such as subjective judgement scales, might be of considerable importance in field rescue scenarios where objective measures such as body core temperature, skin temperature, and oxygen consumption are difficult to obtain. The objective of this study was to evaluate, in healthy subjects, the reliability of the Cold Discomfort Scale (CDS), a subjective judgement scale for the assessment of patient thermal state in cold environments, defined as test-retest stability, and criterion validity, defined as the ability to detect a difference in cumulative cold stress over time. Twenty-two healthy subjects performed two consecutive trials (test-retest). Dressed in light clothing, the subjects remained in a climatic chamber set to -20 °C for 60 min. CDS ratings were obtained every 5 min. Reliability was analysed by test-retest stability using weighted kappa coefficient that was 0.84 including all the 5-min interval measurements. When analysed separately at each 5-min interval the weighted kappa coefficients were was 0.48-0.86. Criterion validity was analysed by comparing median CDS ratings of a moving time interval. The comparison revealed that CDS ratings were significantly increased for every interval of 10, 15, and 30 min (p < 0.001) but not for every interval of 5 min. In conclusion, in a prehospital scenario, subjective judgement scales might be a valuable measure for the assessment of patient thermal state. The results of this study indicated that, in concious patients, the CDS may be both reliable and valid for such purpose.
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