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Mark L Christensen, Grant S Lipman, Dennis A Grahn, Kate M Shea, Joseph Einhorn, H Craig Heller
OBJECTIVE: To compare the effectiveness of arteriovenous anastomosis (AVA) vs heated intravenous fluid (IVF) rewarming in hypothermic subjects. Additionally, we sought to develop a novel method of hypothermia induction. METHODS: Eight subjects underwent 3 cooling trials each to a core temperature of 34.8±0.6 (32.7 to 36.3°C [mean±SD with range]) by 14°C water immersion for 30 minutes, followed by walking on a treadmill for 5 minutes. Core temperatures (Δtes) and rates of cooling (°C/h) were measured...
June 2017: Wilderness & Environmental Medicine
Ken Zafren
Accidental hypothermia is an unintentional drop in core temperature to 35°C or below. Core temperature is best measured by esophageal probe. If core temperature cannot be measured, the degree should be estimated using clinical signs. Treatment is to protect from further heat loss, minimize afterdrop, and prevent cardiovascular collapse during rescue and resuscitation. The patient should be handled gently, kept horizontal, insulated, and actively rewarmed. Active rewarming is also beneficial in mild hypothermia but passive rewarming usually suffices...
May 2017: Emergency Medicine Clinics of North America
Harvey V Lankford
This essay will review historical and medical aspects of cold exposure, hypothermia, and frostbite during the Napoleonic era. The 19th century writings of Dominique Jean Larrey, Pierre Jean Moricheau-Beaupré, and others are used to provide an evocative supporting narrative to illustrate some of the cold illnesses, physiology, and theory of both an earlier era and the present time. Medical care for over a century followed the how but not the why of treating frostbite and hypothermia slowly with snow or cold water rather than heat...
December 2016: Wilderness & Environmental Medicine
John Kenny, SarahJane Cullen, Giles D Warrington
PURPOSE: "Ice-mile" swimming presents significant physiological challenges and potential safety issues, but few data are available. This study examined deep body temperature (BT), respiratory rate (RR), and swim performance in 2 swimmers completing an ice-mile swim of 1 mile (1600 m) in water less than 5°C. METHODS: Two male cold-water-habituated swimmers completed a 1-mile lake swim in 3.9°C water. For comparative purposes, they completed an indoor 1-mile swim in 28...
May 2017: International Journal of Sports Physiology and Performance
Todd E Stewart, Allen C Whitford
BACKGROUND: Exertional heat stroke is a potentially life-threatening disease with varying clinical presentations and severity. Given the severe morbidity that can accompany the disease, the immediate management often begins in the prehospital setting. It is important to have not only a comprehensive understanding of the prehospital cooling methods in addition to hospital management strategies, but an understanding of their potential complications as well. CASE REPORT: A 32-year-old male presented to a San Antonio hospital in March 2014 with progressive confusion, nausea, nonbloody emesis, and ataxia...
November 2015: Journal of Emergency Medicine
Mathias Ströhle, Gabriel Putzer, Emily Procter, Peter Paal
Avalanche victims can become hypothermic within 35 minutes of snow burial. However, reported cooling rates for avalanche victims are highly variable and it is poorly understood how much cooling is influenced by general factors (body composition, clothing, ambient conditions, duration of burial, and metabolism), unknown inter-individual factors or other phenomena (e.g., afterdrop). We report an apparent cooling rate of ∼7°C in ∼60 minutes in a healthy backcountry skier who was rewarmed with forced air and warm fluids and was discharged after 2 weeks without neurological sequelae...
December 2015: High Altitude Medicine & Biology
Kevin C Miller, Erik E Swartz, Blaine C Long
CONTEXT: Current treatment recommendations for American football players with exertional heatstroke are to remove clothing and equipment and immerse the body in cold water. It is unknown if wearing a full American football uniform during cold-water immersion (CWI) impairs rectal temperature (Trec) cooling or exacerbates hypothermic afterdrop. OBJECTIVE: To determine the time to cool Trec from 39.5°C to 38.0°C while participants wore a full American football uniform or control uniform during CWI and to determine the uniform's effect on Trec recovery postimmersion...
August 2015: Journal of Athletic Training
A D Flouris, B J Friesen, M J Carlson, D J Casa, G P Kenny
Immediate treatment with cold water immersion (CWI) is the gold standard for exertional heatstroke. In the field, however, treatment is often delayed due to delayed paramedic response and/or inaccurate diagnosis. We examined the effect of treatment (reduction of rectal temperature to 37.5 °C) delays of 5, 20, and 40 min on core cooling rates in eight exertionally heat-stressed (40.0 °C rectal temperature) individuals. We found that rectal temperature was elevated above baseline (P < 0.05) at the end of all delay periods (5 min: 40...
June 2015: Scandinavian Journal of Medicine & Science in Sports
Yongsuk Seo, Chul-Ho Kim, Edward J Ryan, John Gunstad, Ellen L Glickman, Matthew D Muller
INTRODUCTION: The physiological effects of immersion hypothermia and afterdrop are well-characterized, but the psychological effects are less clear. The purpose of this study was to quantify changes in cognitive function during and after lower body water immersion. METHODS: On separate mornings, nine young healthy men participated in both neutral (35 +/- 1 degree C) and cold (13 +/- 1 degree C) water immersion. Subjects rested in neutral air for 30 min followed by 60 min water immersion to the iliac crest and 15 min of recovery in neutral air...
September 2013: Aviation, Space, and Environmental Medicine
Tiffany A Esmat, Katherine E Clark, Matthew D Muller, Judith A Juvancic-Heltzel, Ellen L Glickman
OBJECTIVE: Sleep deprivation and cold air exposure are both experienced in occupational and military settings but the combined effects of these 2 stressors is unknown. The purpose of this study was to determine the effects of 53 hours of total sleep deprivation on thermoregulation during the rewarming phase (25°C air) after acute cold air exposure (10°C air). METHODS: Eight young men underwent 2 trials in which they either received 7 hours of sleep at night or were totally sleep deprived...
December 2012: Wilderness & Environmental Medicine
Colin K Grissom, Chris H Harmston, John C McAlpine, Martin I Radwin, Brad Ellington, Ellie L Hirshberg, Andre Crouch
OBJECTIVE: To measure afterdrop and rewarming in subjects placed in a hypothermia wrap immediately after extrication from 60 minutes of snow burial. METHODS: We measured esophageal core body temperature (Tes) in 6 subjects buried in compacted snow (mean density 39%) for up to 60 minutes at an altitude of 2450 m while breathing with an AvaLung (Black Diamond Equipment, Salt Lake City, UT). Mean snow temperature was -3.5 ± 1.0 °C and mean air temperature was 0 ± 2 °C...
September 2010: Wilderness & Environmental Medicine
J Peter Lundgren, Otto Henriksson, Thea Pretorius, Farrell Cahill, Gerald Bristow, Alecs Chochinov, Alexander Pretorius, Ulf Bjornstig, Gordon G Giesbrecht
OBJECTIVE: To compare four field-appropriate torso-warming modalities that do not require alternating-current (AC) electrical power, using a human model of nonshivering hypothermia. METHODS: Five subjects, serving as their own controls, were cooled four times in 8 degrees C water for 10-30 minutes. Shivering was inhibited by buspirone (30 mg) taken orally prior to cooling and intravenous (IV) meperidine (1.25 mg/kg) at the end of immersion. Subjects were hoisted out of the water, dried, and insulated and then underwent 120 minutes of one of the following: spontaneous warming only; a charcoal heater on the chest; two flexible hot-water bags (total 4 liters of water at 55 degrees C, replenished every 20 minutes) applied to the chest and upper back; or two chemical heating pads applied to the chest and upper back...
July 2009: Prehospital Emergency Care
M J Tindall, M A Peletier, N M W Severens, D J Veldman, B A J M de Mol
A mathematical model is presented to understand heat transfer processes during the cooling and re-warming of patients during cardiac surgery. Our compartmental model is able to account for many of the qualitative features observed in the cooling of various regions of the body including the central core containing the majority of organs, the rectal region containing the intestines and the outer peripheral region of skin and muscle. In particular, we focus on the issue of afterdrop: a drop in core temperature following patient re-warming, which can lead to serious post-operative complications...
December 2008: Mathematical Medicine and Biology: a Journal of the IMA
Colin K Grissom, John C McAlpine, Chris H Harmston, Martin I Radwin, Gordon G Giesbrecht, Mary Beth Scholand, J Scott Morgan
INTRODUCTION: Hypercapnia during avalanche burial may increase core temperature cooling rate by decreasing the temperature threshold for shivering or by increasing respiratory heat loss. METHODS: We studied the effect of hypercapnia on rectal core temperature (T(re)) cooling rate, respiratory heat loss, heat production, and the T(re) shivering threshold during snow burial (mean snow temperature -3.2 + 2.7 degrees C) in 11 subjects. In a 60-min hypercapnic burial subjects breathed a 5% carbon dioxide and 21% oxygen inhaled gas mixture and in a separate 60-min normocapnic burial subjects breathed ambient air...
August 2008: Aviation, Space, and Environmental Medicine
Natascha M W Severens, Wouter D van Marken Lichtenbelt, Gerard M J van Leeuwen, Arjan J H Frijns, Anton A van Steenhoven, Bas A J M de Mol, Harry B van Wezel, Dirk J Veldman
OBJECTIVES: After cardiopulmonary bypass, patients often show redistribution hypothermia, also called afterdrop. Forced-air blankets help to reduce afterdrop. This study explores the effect of forced-air blankets on temperature distribution and peripheral perfusion. The blood perfusion data is used to explain the observed temperature effects and the reduction of the afterdrop. METHODS: Fifteen patients were enrolled in a randomised study. In the test group (n=8), forced-air warmers were used...
December 2007: European Journal of Cardio-thoracic Surgery
N M W Severens, W D van Marken Lichtenbelt, A J H Frijns, A A Van Steenhoven, B A J M de Mol, D I Sessler
A core temperature drop after cardiac surgery slows down the patient's recuperation process. In order to minimize the amount of the so-called afterdrop, more knowledge is needed about the impaired thermoregulatory system during anesthesia and the effect of different protocols on temperature distribution. Therefore, a computer model has been developed that describes heat transfer during cardiac surgery. The model consists of three parts: (1) a passive part, which gives a simplified description of the human geometry and the passive heat transfer processes, (2) an active part that takes into account the thermoregulatory system as a function of the amount of anesthesia and (3) submodels, through which it is possible to adjust the boundary conditions...
September 7, 2007: Physics in Medicine and Biology
Michele V Hultzer, Xiaojiang Xu, Claudia Marrao, Gerald Bristow, Alex Chochinov, Gordon G Giesbrecht
OBJECTIVE: To compare 5 active torso-warming modalities in a human model of severe hypothermia with shivering heat production inhibited by intravenous meperidine. METHODS: Six subjects were cooled on 6 different occasions each, in 8 degrees C water, for 30 minutes or to a core temperature of 35 degrees C. Spontaneous warming was the first torso-warming modality to be tested for every subject, and results served both as a comparative control and for determination of the meperidine dose for subsequent trials...
November 2005: CJEM
Heather E Wright, Stephen S Cheung
INTRODUCTION: Rewarming from hypothermia in a field setting is a challenge due to the typical lack of significant power or heat source, making the targeted application of available heat critical. The highly vascular area of the head and neck may allow heat to be rapidly transferred to the core via blood circulation. At the same time, the warming of only a small skin surface may minimize the rapid rise in skin temperature proposed to attenuate shivering and endogenous heat production. Therefore, we investigated the efficacy of targeting the head and neck for rewarming from mild hypothermia...
April 2006: Aviation, Space, and Environmental Medicine
Gordon G Giesbrecht, John S Hayward
A case description is presented of a 9-member rowing team whose scull swamped on a small lake in Victoria, Canada, because of a sudden winter storm, which immersed them in 4 degrees C water for 50 minutes until a small rescue boat found them in darkness. Another 13 minutes of cold exposure in 6.7 degrees C air occurred during boat transport to waiting ambulance paramedics. Two rowers died, one from severe hypothermia and the other from drowning as a consequence of cold incapacitation and hypothermia. The 2 coldest rowers, who were transported 8 km to a major hospital, arrived with rectal temperatures of 23...
2006: Wilderness & Environmental Medicine
Won Gon Kim, Ji Hyuck Yang
In an attempt to find an adequate end-point rewarming temperature after hypothermic cardiopulmonary bypass (CPB), 50 pediatric patients who underwent cardiac surgery were randomly assigned for the end-point rectal rewarming temperature at either 35.5 (Group 1) or 37.0 degrees C (Group 2). The patients' rectal temperature, with heart rate and blood pressure, was measured 0.5, 1.0, 4.0, 8.0, and 16.0 h after the arrival in the intensive care unit. For all patients, nonpulsatile perfusion with a roller pump and a membrane or bubble oxygenator was used for oxygenation...
November 2005: Artificial Organs
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