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Hypothermia

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Other Names

  • Hypothermia
  • Cold Injury
  • Accidental hypothermia
  • Primary accidental hypothermia
  • Secondary hypothermia
  • Environmental hypothermia

Background

  • This page refers to hypothermia, a condition defined as core body temperature below 35°C (95°F)
    • Occurs when total body heat loss exceeds physiologic heat production
    • Note this page refers to primary environmental or accidental hypothermia and not secondary hypothermia

History

Epidemiology

  • Prevalence
    • In the united states, responsible for approximately 1500 deaths per year[1]
  • Incidence
    • Ranges from 0.13 to 6.9 cases per 100,000 per year in Europe, New Zealand[2][3]
    • Responsible for 2 deaths per 100,000 per year in Scotland[4]
    • Responsible for 5 deaths per 100,000 per year in Poland[5]
  • Prevalence
    • 50% of deaths occur in patients > 65 years old[6]

Pathophysiology

Differential diagnosis of secondary hypothermia (click to enlarge)[7]
  • General
    • Core temperature drops below 35°C (95°F)
    • Occurs when total body heat loss exceeds physiologic heat production
    • As hypothermia worsens, vitals signs decrease slowly until cardiac arrest occurs
    • Organs affected: heart, brain, kidney, blood coagulation, and, possibly, the immune system
  • Normal temperature regulation
    • Humans are homeothermic, normal temperature is 37 ± 0.5 °C
    • Core temperature is regulated by central and peripheral processes
    • Centrally, the hypothalamus controls temperature
    • Peripherally, vasoconstriction and dilation, shivering, and sweating help

Terminology

  • Thermoregulation impaired by external source
    • Conduction
    • Convection
    • Evaporation
    • Radiation (primary hypothermia)
  • Impaired thermoregulation due to other pathology
    • Due to things like trauma, stroke, shock, etc
    • Termed secondary hypothermia

Natural History

  • Environmental cooling
    • Windy and wet environment will speed cooling
    • Wind chill index: ambient air temperature + wind speed on the skin surface temperature[8]
    • Avalanches: cooling rate of buried victims may reach 9 °C/h
    • Water immersion: at temp of 1–2 °C, can reach 5 °C/10 min[9]
    • Cooling rate in cold water immersion is highly variable and depends on conditions, slower but still significant
    • During avalanche burial, hypercapnia can also lead to rapid cooling (need citation)
  • Cardiac Arrest
    • A person immersed in cold water (<15 °C) can arrest after 30 min[10]
    • In a young healthy individual, cardiac arrest may occur below 30 °C
    • In elderly patients with comorbidities, this can occur when core temperature drops below 32 °C
    • Vital signs can be present with core temperature below 24 °C[11]
    • Lowest documented survival from accidental hypothermia is 13.7 °C (need citation)
    • Note hypothermic cardiac arrest is fundamentally different from normthermic cardiac arrest
  • Following Extrication
    • Cooling continues as warm central blood is redistributed to the cold periphery by a countercurrent heat exchange
    • Cooling may also continue from conduction of heat from the core to cooler surface tissues
    • Shivering may or may not be present. The absence of shivering suggests spontaneous rewarming may not be possible
    • Normal level of consciousness correlates with a low risk of hypothermic cardiac arrest[12]
  • Rescue collapse/ arrest
    • A term applied when cardiocirculatory collapse occurs during extrication or transfer of a hypothermic patient
    • Stated different, this may be a witnessed cardiac arrest[13]
    • Pathophysiology of a "rescue arrest" is not well understood
    • Likely some combination of hypovolemia, cardiac dysrhythmias triggered by interventions, mechanical stimuli such as sudden movement
    • Cardiac arrest may also be caused by afterdrop (further cooling, even after rewarming has started)
    • One study found the core temp in witnessed hypothermic cardiac arrest was 23.9 °C +/- 2.7 °C.
    • Rescue collapse appears to double the risk of death in severely hypothermic patients[14]

Etiology

  • Modern countries
    • Primarily affects people who live, work or recreate outside
  • Less developed country
    • More significant impacts from homelessness, mass accidents, natural disasters

Risk Factors

  • Temperature
    • Risk increases as temperature drops
    • However many cases occur during low/moderate cold stress with prolonged exposure
  • Socioeconomic
    • Homelessness
    • Alcohol or drug use
  • Environmental
    • Cold or temperate, wet climates
    • Mountains
    • Natural Disasters
  • Demographic
    • Children, low BMI adults due to large surface area to weight ratio[15]
    • Geriatric patients living alone with multiple comorbidities[16]
  • Sports
    • Mountaineering
    • Diving

Differential Diagnosis

Clinical Features

  • History
    • History of cold exposure
    • Symptoms can vary wildly depending on duration of exposure, core temperature
    • Range from shivering to cardiac arrest (see classification)
  • Physical Exam
    • Patients with mild symptoms may be shivering, be cold peripherally
    • Sicker patients may be altered, bradycardic
    • As core temperature drops, vital signs become unstable and cardiac arrest can occur
    • Vital signs tend to decrease linearly with core temperature[17]
    • Presence or absence of shivering can not be used to diagnose hypothermia
    • Level of consciousness is the best way to measure severity in the absence of a core temperature
  • Special Tests

Evaluation

Example of epitympanic thermomemter. A thermoster based device is designed for outdoor use.[18]
  • Diagnosis is primarily clinical
    • Out of hospital diagnosis can be challenging
    • Core temperature can help guide management decisions
    • If thermometer not available, treat based on clinical presentation and suspicion of hypothermia
    • Imaging is not generally needed

Temperature Measurement

  • General Points
    • Out of hospital
      • Can touch patients chest and use the revised Swiss system if no thermometer
      • Thermistor based epitympanic probe in non-intubated patients
      • Esophageal probe or deep nasopharyngeal probe if intubated
    • In hospital
      • Urinary bladder temperature is widely used and accepted
    • Infrared epitympanic devices useful for screening, not for monitoring
  • Optimal thermometer
    • Minimally invasive, easy to use, hygienic, independent of environmental conditions, measures core temperature with high accuracy, and has a short response time
    • No such device exists
  • Not practical, influence by environmental conditions
    • Skin
    • Temporal artery
    • Oral
    • Axillary temperatures
    • Infrared tympanic
  • Thermistor based epitympanic temperature measurement[19]
    • Device intended for outdoor use, well insulated
  • Nonvascular central thermometers
    • Designed to correlate with pulmonary artery catheter measurement (most accurate method of core temp measurement)
    • Includes esophageal, urinary bladder, rectal, and nasopharyngeal thermometers
    • Can lag behind true core temp, have thermal inertia due to surrounding tissue and bodily contents[20]
    • Esophageal or epitympanic give the best estimate of true brain temperature
  • Future technology
    • Not yet ready for clinical use
    • Includes microwave and zero-heat-flux thermometers

Classification

Classical Staging of Accidental Hypothermia

Stage Core Findings Estimated Core Temperature °C (°F)
Hypothermia I (mild) Conscious, shivering, social withdrawal, minor behavior changes[21] 32°C to 35°C (89.6°F-95°F)
Hypothermia II (moderate) Impaired consciousness; may or may not be shivering, pupils dilate, cardiac arrythmias can occur 28°C to 32°C (82.4°F-89.6°F)
Hypothermia III (severe) Unconscious*; vital signs present, severe bradycardia, ventricular fibrillation, loss of DTR, loss of volitional motion <28°C (86°F)
Hypothermia IV (severe) Cardiac arrest, Apparent death, vital signs absent <24°C (75°F)**
  • **Cardiac arrest can occur at earlier or later stages of hypothermia. Some patients may have vital signs with core temperatures < 24 °C.

Management

Principles of Pre-hospital Management (Revised Swiss System)

Stage I Stage II Stage III Stage IV
Clinical findings** Alert Verbal Painful or Unconscious, vital signs present Unconscious, vital signs absent
Risk of cardiac arrest Low Moderate High Hypothermic Cardiac Arrest
Oxygen administration Y Y Y Y
Carbohydrates Warm sweet tea, sweet bars Glucose IV/IO Glucose IV/IO N/A
Active movement Y N N N
Passive rewarming Y Y Y Y
Active rewarming Consider Y Y Y
Cautious mobilization/ horizontal transport N Y Y N
Defibrillation pads N Y Y Y
Intubation N N Consider Y
CPR N N N Y
Defibrillation N N N Y
Drugs (ACLS) N N N Y
Hospitalization with ECMO N N Y Y
  • **In the revised Swiss system, “Alert” corresponds to a GCS score of 15. “Verbal” corresponds to GCS scores of 9–14, including confused patients. “Painful” and “Unconscious” correspond to GCS scores < 9.

Prehospital

Example of a commercial hypothermia bag
  • Primary objectives
    • Early recognition is critical
    • Remove from cold environment
    • Prevent/ slow further heat loss
    • Initiate rewarming as soon as possible
    • Note: core temperature can decrease during medical care, exposure, analgesia, anesthesia, infusion of fluids[22]
  • Critical actions
    • Rewarming often not feasible due limited equipment, short transport times
    • Emphasis on preventing further heat loss
    • Essential measures: extricate from cold, limit heat loss, rapid transportation
  • Mild hypothermia (stage I)
    • Typically fully alert, making diagnosis straight forward
    • Can often be managed on site without transport
    • Passive rewarming by removing from cold, increase insulation, warm drinks, active movements
  • Moderate or severe hypothermia (stage II, III)
    • Prevent further heat loss
      • Require active rewarming. The entire body should be insulated.
      • If horizontal, place on a stretcher with insulation from the ground
      • Wet clothing should be removed in a protected environment, dry clothing or layers applied
      • Chemical or electrical heat packs should be placed on trunk (avoid directly on the skin, prevent burns)
      • Vapour barrier should be added, can be packed with dry clothing or blankets
    • If supine, leave supine for at least 30 minutes before allowing to walk
      • Allows for shivering, calorie consumption
      • Walking can increase heat production, also increases after drop
    • Rewarming out of hospital is challenging
      • Attempts to rewarm should not delay transport
      • Apply oxygen, place on monitor, apply defibrillation pads
      • Obtaining IV access can be difficult due to vasoconstriction, consider IO as needed
      • Warm IV fluids (38 to 42 C) should be given in boluses, guided by vital signs
    • Most dysrhythmias will improve with rewarming
      • This includes supraventricular rhythms such as atrial fibrillation
    • Avoid endotracheal intubation unless necessary
      • Defer until the patient is in a warm environment if possible
      • Most drugs are not effective in hypothermia, tubes are less pliable, IV lines can freeze
      • Rigidity, trismus can make intubation difficult
      • End tidal CO2 is not reliable in hypothermia[23]
  • Hypothermia without vital signs (stage IV)
    • Diagnosis is hypothermic cardiac arrest
      • Note that this can be difficult to assess in an unconsious, hypothermic patient
      • Vital signs can be minimal, difficult to detect or palpate
      • Recommend spending 60 seconds looking for vital signs before beginning CPR/ ACLS
      • Can augment exam with electrocardiogram, ultrasound and capnography to identify presence of vital signs
    • Cardiopulmonary Resuscitation
      • CPR is performed the same as a euthermic patient
      • Can attempt up to 3 shocks for ventricular fibrillation with core temperature <30 °C
      • If 3 unsuccessful, refrain from further shocks until core temperature above 30 °C
      • Epinephrine, amiodarone are not indicated for temperature <30 °C
      • The administration interval for epinephrine is 6 to 10 minutes (instead of 3 to 5)
      • Once normothermia is achieved, standard ACLS protocols should be followed
    • Prehospital triage
      • Do not start CPR if valid DNR, clear signs of irreversible death (livor mortis), danger or exhaustion to resucers, avalanche burial more than 60 minutes with asystole, completely obstructed airway
      • Hypothermic rigidity (pseudo rigor mortis) is not a reliable sign of death[24]
      • The following are not contraindications to rewarming a hypothermic patient in cardiac arrest: asystole, unwitnessed CA, low core temperature, long no-flow or low-flow time, fixed, dilated pupils, hypocapnia (ETCO2 <10 mmHg), old age, or trauma (even major trauma
    • Patient referral and transport
      • The patient should be transferred to an ECMO center for the following: cardiac arrest, core temperature < 30 C, systolic blood pressure < 90 mmHg, or ventricular dysrhythmia
      • Consider stopping at a non ACLS hospital for hospital triage
      • HOPE score can estimate survival probability: https://hypothermiascore.org/
      • Perform continuous CPR if possible during transport
Table of rewarming techniques for hypothermia (click to enlarge)[25]

Hospital

  • General
    • Treatment depends on circulatory status, stage of hypothermia, available resources
  • Types of rewarming (see table)
    • Passive: increases core temperature without exogenous heat
    • Active: exogenous heat is delivered
    • Active rewarming can be external or internal
    • Most patients require passive and active external rewarming
    • Hemodynamic instability and cardiac arrest are indications for active internal rewarming
  • Mild hypothermia (stage I)
    • Passive rewarming, active external rewarming
    • Can consider minimally invasive internal rewarming such as warm oral fluids
    • Shivering, active movement will speed rewarming
    • Temperature goal: normothermia with a core temperature about 37 °C
  • Moderate/ severe hypothermia (stage II, III)
    • Includes patients at risk of cardiac arrest
    • Active rewarming is necessary
    • External is often effective, if it is not, internal rewarming should be initiated
    • Signs of failure of external rewarming: core temperature unchanged or decreasing, elevated lactate, worsening mental status, decreased blood pressure, ventricular dysrhthmias
    • Active internal methods to consider include catheters and continuous renal replacement therapy (CRRT)
  • Cardiac arrest (Stage IV)
    • These patients are pulseless, require active CPR
    • Extracorporeal life support (ECLS) are the preferred method of rewarming, includes cardiopulmonary bypass and Extracorporeal Membrane Oxygenation (ECMO)[26]
    • If not available, additional other forms of active, internal rewarming should be employed during resuscitation including:
      • Bladder Lavage
      • Gastric Lavage
      • Thoracic Lavage
      • Peritoneal Lavage
      • Move the patient to a warm room
    • Continuous Renal Replacement Therapy and Hemodialysis should be reserved for patients with a pulse
    • Target rewarming rate is <5 °C/h[27]
      • However, a slower rate of rewarming (approximately 2 °C/h) may be associated with improved survival with good neurologic outcome[28]
    • Etracorporeal Membrane Oxygenation (ECMO)
      • Preferred method, can be maintained post-ROSC
      • Helps manage other common complications including ARDS (adult respiratory disress syndrome)
    • Volume replacement
      • IV fluids should be warmed to 40 °C to avoid cooling, however not effective in rewarming
      • Patients may require generous IV fluid resuscitation due to hypothermia induced plasma shifts and cold-induced diuresis
    • HOPE score can be used to predict outcomes[29]
    • Termination of CPR
      • Consider if potassium > 12 or persistent asystole with temperature > 32 °C

Prevention

  • General
    • Important to understand weather conditions, air temperatures, wind chill, water temperatures, and the planned exercise
    • Need to determine if it is safe to continue with planned event
    • Event coordinators and medical directors should consider having an ambient and wind-chill temperature guideline
  • Temperature thresholds
    • Many governing bodies cancel events or modify training for temperatures below −20°C (–4°F)[30]
    • No practice or training at ambient temperatures of −23°C (–10°F) or wind chill of −40°C (–40°F)
    • For swimming, USA triathalon recommends shortening swims for temperatures of 53°F to 56°F (11.7°C-13.3°C), cancelling events for water temperatures of less than 53°F (11.7°C)[31]
  • Clothing layers
    • Proper clothing layering, ability to respond to changing weather conditions
    • Athletes should individualize layering based on past cold weather experiences and training
    • Innermost layer should wick sweat away from the body to reduce cold injury risk
      • Should transfer the water/sweat to outer layers of clothing
      • Note wool can retain heat even when wet
      • Good base layers include polypropylene, polyester, and synthetic wool
      • Avoid cotton, which traps moisture
    • Middle layers are for insulation
      • Often made from fleece or wool
    • Outer layer should allow moisture transfer, ventilation, protection against wind and rain
      • Should be worn as needed, especially in wet conditions to maintain dry internal layers
    • Hats, balaclavas should be worn to protect heat loss from the head
    • Mittens protect the hands better than gloves
  • Clohing factors
    • Waterproof cothing
      • Often advertised as "breathable"
      • Exercise sweat rates may exceed the breathability of these materials
      • Assume the more waterproof clothing is, the less it will breath
    • Fitt
      • Clothing should be well fitting, not too tight or too loose
      • If it is too tight, it can constrict peripheral blood flow and increase risk
      • If more than one pair of socks is worn, increase shoe size
    • Chemical warmers
      • Can be used to maintain peripheral warmth
    • Avoid skin protecting emollients which increase the risk of frostbite[32]
    • Avoid vasoconstricting substances (alcohol, caffeine, medications)
  • Caloric intake
    • Shivering, heavy clothing and increased workload can increase energy expenditure by up to 40%
    • Increased calories must be obtained through frequent snacks
    • Carbohydrate rich foods are recommended
    • Maintain good hydration
  • Training
    • Important to train for cold weather exercise
    • Collapse from fatigue or exhaustion greatly increases risk of hypothermia, frost bite
  • Recognition
    • Important for individuals and team to recognize early signs and symptoms of frostbite and hypothermia
    • This can prevent worsening of the conditions and corrective actions by the individual
    • Frequent cold checks with a buddy are recommended

Rehab and Return to Play

Rehabilitation

  • Needs to be updated

Return to Play/ Work

  • Needs to be updated

Complications and Prognosis

Prognosis

Complications

See Also

References

  1. ↑ Baumgartner, E.A.; Belson, M.; Rubin, C.; Patel, M. Hypothermia and other cold-related morbidity emergency department visits: United States, 1995–2004. Wilderness Environ. Med. 2008, 19, 233–237.
  2. ↑ Herity, B.; Daly, L.; Bourke, G.J.; Horgan, J.M. Hypothermia and mortality and morbidity. An epidemiological analysis. J. Epidemiol. Commun. Health 1991, 45, 19–23.
  3. ↑ Taylor, N.A.; Griffiths, R.F.; Cotter, J.D. Epidemiology of hypothermia: Fatalities and hospitalisations in New Zealand. Aust. N. Z. J. Med. 1994, 24, 705–710.
  4. ↑ Hislop, L.J.; Wyatt, J.P.; McNaughton, G.W.; Ireland, A.J.; Rainer, T.H.; Olverman, G.; Laughton, L.M. Urban hypothermia in the west of Scotland. West of Scotland Accident and Emergency Trainees Research Group. BMJ 1995, 311, 725.
  5. ↑ Kosinski, S.; Darocha, T.; Galazkowski, R.; Drwila, R. Accidental hypothermia in Poland—Estimation of prevalence, diagnostic methods and treatment. Scand. J. Trauma Resusc. Emerg. Med. 2015, 23, 13.
  6. ↑ Centers for Disease Control and Prevention: Hypothermia-related deaths—United States, 2003 2004. MMWR Morb Mortal Wkly Rep 54: 173, 2005
  7. ↑ Paal, P.; Gordon, L.; Strapazzon, G.; Brodmann Maeder, M.; Putzer, G.; Walpoth, B.; Wanscher, M.; Brown, D.; Holzer, M.; Broessner, G.; et al. Accidental hypothermia-an update: The content of this review is endorsed by the International Commission for Mountain Emergency Medicine (ICAR MEDCOM). Scand. J. Trauma Resusc. Emerg. Med. 2016, 24, 111.
  8. ↑ Lankford, H.V.; Fox, L.R. TheWind-Chill Index. Wilderness Environ. Med. 2021, 32, 392–399.
  9. ↑ Proulx, C.I.; Ducharme, M.B.; Kenny, G.P. Effect of water temperature on cooling efficiency during hyperthermia in humans. J. Appl. Physiol. 2003, 94, 1317–1323.
  10. ↑ Tipton, M.J.; Collier, N.; Massey, H.; Corbett, J.; Harper, M. Cold water immersion: Kill or cure? Exp. Physiol. 2017, 102, 1335–1355.
  11. ↑ Pasquier, M.; Zurron, N.; Weith, B.; Turini, P.; Dami, F.; Carron, P.N.; Paal, P. Deep accidental hypothermia with core temperature below 24 degrees c presenting with vital signs. High Alt. Med. Biol. 2014, 15, 58–6
  12. ↑ Musi, M.E.; Sheets, A.; Zafren, K.; Brugger, H.; Paal, P.; Holzl, N.; Pasquier, M. Clinical staging of accidental hypothermia: The Revised Swiss System: Recommendation of the International Commission for Mountain Emergency Medicine (ICAR MedCom). Resuscitation 2021, 162, 182–187.
  13. ↑ Frei, C.; Darocha, T.; Debaty, G.; Dami, F.; Blancher, M.; Carron, P.N.; Oddo, M.; Pasquier, M. Clinical characteristics and outcomes of witnessed hypothermic cardiac arrest: A systematic review on rescue collapse. Resuscitation 2019, 137, 41–48
  14. ↑ Podsiadlo, P.; Smolen, A.; Kosinski, S.; Hymczak, H.;Waligorski, S.;Witt-Majchrzak, A.; Drobinski, D.; Nowak, E.; Barteczko- Grajek, B.; Toczek, K.; et al. Impact of rescue collapse on mortality rate in severe accidental hypothermia: A matched-pair analysis. Resuscitation 2021, 164, 108–113.
  15. ↑ Singer, D. Pediatric Hypothermia: An Ambiguous Issue. Int. J. Environ. Res. Public Health, 2021, in press.
  16. ↑ Danzl, D.F.; Pozos, R.S. Accidental hypothermia. N. Engl. J. Med. 1994, 331, 1756–1760.
  17. ↑ Pasquier, M.; Cools, E.; Zafren, K.; Carron, P.N.; Frochaux, V.; Rousson, V. Vital Signs in Accidental Hypothermia. High Alt. Med. Biol. 2021, 22, 142–147.
  18. ↑ Lapostolle, Frédéric, et al. "Hypothermia in trauma victims at first arrival of ambulance personnel: an observational study with assessment of risk factors." Scandinavian journal of trauma, resuscitation and emergency medicine 25.1 (2017): 1-6.
  19. ↑ Walpoth, B.H.; Galdikas, J.; Leupi, F.; Muehlemann, W.; Schlaepfer, P.; Althaus, U. Assessment of hypothermia with a new “tympanic” thermometer. J. Clin. Monit. 1994, 10, 91–96.
  20. ↑ Stone, J.G.; Young,W.L.; Smith, C.R.; Solomon, R.A.;Wald, A.; Ostapkovich, N.; Shrebnick, D.B. Do standard monitoring sites reflect true brain temperature when profound hypothermia is rapidly induced and reversed? Anesthesiology 1995, 82, 344–351.
  21. ↑ McMahon JA, Howe A. Cold weather issues in sideline and event management. Curr Sports Med Rep. 2012;11:135-141.
  22. ↑ Rauch, S.; Miller, C.; Brauer, A.;Wallner, B.; Bock, M.; Paal, P. Perioperative Hypothermia—A Narrative Review. Int. J. Environ. Res. Public Health 2021, 18, 8749.
  23. ↑ Darocha, T.; Kosinski, S.; Jarosz, A.; Podsiadlo, P.; Zietkiewicz, M.; Sanak, T.; Galazkowski, R.; Piatek, J.; Konstanty-Kalandyk, J.; Drwila, R. Should capnography be used as a guide for choosing a ventilation strategy in circulatory shock caused by severe hypothermia? Observational case-series study. Scand. J. Trauma Resusc. Emerg. Med. 2017, 25, 15.
  24. ↑ Pasquier, M.; Zurron, N.; Weith, B.; Turini, P.; Dami, F.; Carron, P.N.; Paal, P. Deep accidental hypothermia with core temperature below 24 degrees c presenting with vital signs. High Alt. Med. Biol. 2014, 15, 58–63.
  25. ↑ Paal, Peter, et al. "Accidental hypothermia: 2021 update." International journal of environmental research and public health 19.1 (2022): 501.
  26. ↑ Swol, J.; Darocha, T.; Paal, P.; Brugger, H.; Podsiadlo, P.; Kosinski, S.; Puslecki, M.; Ligowski, M.; Pasquier, M. Extracorporeal Life Support in Accidental Hypothermia with Cardiac Arrest-A Narrative Review. ASAIO J. 2021.
  27. ↑ Kornberger, E.; Schwarz, B.; Lindner, K.H.; Mair, P. Forced air surface rewarming in patients with severe accidental hypothermia. Resuscitation 1999, 41, 105–111.
  28. ↑ Darocha, T.; Podsiadlo, P.; Polak, M.; Hymczak, H.; Krzych, L.; Skalski, J.; Witt-Majchrzak, A.; Nowak, E.; Toczek, K.; Waligorski, S.; et al. Prognostic Factors for Nonasphyxia-Related Cardiac Arrest Patients Undergoing Extracorporeal—HELP Registry Study. J. Cardiothorac. Vasc. Anesth. 2020, 34, 365–371.
  29. ↑ Pasquier, M.; Rousson, V.; Darocha, T.; Bouzat, P.; Kosinski, S.; Sawamoto, K.; Champigneulle, B.;Wiberg, S.;Wanscher, M.C.J.; Brodmann Maeder, M.; et al. Hypothermia outcome prediction after extracorporeal life support for hypothermic cardiac arrest patients: An external validation of the HOPE score. Resuscitation 2019, 139, 321–328.
  30. ↑ International Ski Federation (FIS). The International Ski Competition Rules (ICR). http://www.fis-ski.com/mm/Document/documentlibrary/Cross-Country/02/95/69/ICRCross-Country2013_clean_English.pdf.
  31. ↑ USA Triathlon race director toolbox: water temperature recommendations chart. http://www.usatriathlon.org/audience/race-directors/race-director-toolbox.aspx. Accessed September 7, 2015.
  32. ↑ Lehmuskallio E. Cold protecting ointments and frostbite: a questionnaire study of 830 conscripts in Finland. Acta Derm Venereol. 1999;79:67-70.
Created by:
John Kiel on 30 June 2019 22:53:47
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Last edited:
25 July 2022 20:49:58
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