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- 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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| 2. |
- Lundgren, Peter, 1977-
(författare)
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Protection and treatment of hypothermia in prehospital trauma care : with emphasis on active warming
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background: In prehospital trauma care active warming is recommended to aid in protection from further cooling. However, scientific evidence of the effectiveness of active warming in a clinical setting is scarce. Also, evaluating the effectiveness of active warming, especially in harsh ambient conditions, by objective measures, is difficult. Objective: To evaluate the effectiveness of field applicabe heat sources (I) and to evaluate active warming intervention in a prehospital clinical setting (II and III). To evaluate reliability and validity of the Cold Discomfort Scale (CDS), a subjective judgement scale for assessment of the thermal state of patients in a cold environment (IV). Methods: In a laboratory trial, non-shivering hypothermic subjects (n=5), were cooled in 8 ºC water followed by spontaneous warming, a charcoal heater, two flexible hot-water bags or two chemical heat pads, all applied to the chest and upper back (I). Oesophageal temperature, skin temperature, heat flux, oxygen consumption, respiratory rate and, heart rate were measured. In two clinical randomized trials, shivering patients during road and air ambulance transport (II) and during field treatment (III) were randomized to either passive warming alone (n=22 and n=9) or to passive warming with the addition of a chemical heat pad (n=26 and n=11). Body core temperature, respiratory rate, heart rate, blood pressure (II) and the patients’ subjective sensation of thermal comfort (II and III) were measured. In a laboratory trial, shivering subjects were exposed to – 20 ºC (n=22). The CDS was evaluated regarding reliability, defined as test-retest stability, and criterion validity, defined as the ability to detect changes in cold discomfort due to changes in cumulative cold stress (IV). Results: In non-shivering hypothermic subjects postcooling afterdrop was significantly less for the chemical heat pads, but not for the hot water bags and the charcoal heater, compared to spontaneous warming (I). Temperature drop during the entire warming phase was significantly less for all the heat sources respectively, compared to spontaneous warming (I). During road and air ambulance transport, ear canal temperature was significantly increased and cold discomfort significantly decreased, both in patients assigned to passive warming only, and in patients assigned to additional active warming (II). During field treatment, cold discomfort was significantly reduced in patients assigned to additional active warming, but remained the same in patients assigned to passive warming only (III). Weighted kappa coefficient, describing test-retest stability, was 0.84 (IV). CDS ratings were significantly increased during each 30 minutes interval (IV). Conclusion: In non-shivering hypothermic subjects, heat sources were effective to attenuate afterdrop, when providing high heat content over a large surface area and effective to continue to increase body core temperature when providing sustained high heat content. In shivering trauma patients, adequate passive warming were sufficient treatment to prevent afterdrop, to slowly increase body core temperature, and to reduce cold discomfort. If inadequate passive warming, additional active warming was required to reduce cold discomfort. The CDS, a subjective judgement scale for assessment of the thermal state of patients in a cold environment seemed to be reliable regarding test-retest stability and valid regarding ability to detect change in cumulative cold stress.
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| 3. |
- Nilsson, Heléne
(författare)
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Demand for Rapid and Accurate Regional Medical Response at Major Incidents
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The ultimate goal in major incidents is to optimize care for the greatest number of patients. This means matching patients with facilities that have the appropriate resources available in sufficient quantities to provide the necessary care. A major incident is a situation where the available resources are inadequate in relation to the urgent need. As health care resources have become increasingly constrained, it is imperative that all resources be optimized from a regional and sometimes a national perspective.In Sweden, the number of major incidents per year is still unknown. In order to implement effective quality control of response to major incidents, specific standards for regional medical response need to be set and agreed on from a national perspective. This will probably also enhance follow-up and comparison of major incidents in the future.The overall aim of this thesis is to improve understanding of the demand for rapid and accurate regional medical response at major incidents. The objectives were to systematically analyse specific decisions within regional medical response and to identify factors that can influence patient outcome in major incidents.This research is based on four studies in which a set of 11 measurable performance indicators for initial regional medical command and control have been used as an evaluation instrument together with a simulation system where the assessment of each patient could be evaluated. The collection of data was made during several disaster management programs but also in real major incidents that occurred in two county councils in Sweden. In one of the studies, the national disaster medical response plan for burns was evaluated.This research shows that measurable performance indicators for regional medical response allow standardized evaluation such that it is possible to find crucial decisions that can be related to patient outcome. The indicators can be applied to major incidents that directly or indirectly involve casualties provided there is sufficient documentation available and thereby could constitute a measurable part of regional and national follow-up of major incidents. Reproducible simulations of mass casualty events that combine process and outcome indicators can create important results on medical surge capability and may serve to support disaster planning.The research also identified that there is a risk for delay in distribution of severely injured when many county councils needs to be involved due to different regional response times to major incidents. Furthermore, the coordination between health care and other authorities concerning ambulance helicopter transport in mass casualty events needs to be further addressed. It is concluded that there is a demand for rapid and accurate response to major incidents that is similar in all county councils. Like all other fields of medicine, these processes need to be quality assured.
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