Board Review: Hypothermia/Cold Water Submersion

Author: Kevin P. Beres, DO PGY-1
UTHealth Emergency Medicine Resident

Originally Published: Modern Resident, April/May 2015 

Growing up in Wisconsin, one of the beloved New Year’s traditions was the polar bear plunge, which translates to a group of people jumping into the cold lakes on New Year’s Day. This event brings up two important concepts: cold water submersion and accidental hypothermia. Risk factors for accidental hypothermia include alcohol, AMS, behavior, extreme ages and certain comorbidities including peripheral vascular disease, trauma and diabetes mellitus.[1,2]

Cold Water Submersion:
When the body comes into contact with cold water, it leads to activation of the Mammalian diving reflex, resulting in bradycardia, shunting of blood to the CNS system and slow metabolism and may actually prolong survival.[1] This reflex affects children more efficiently than adults. Alcohol has been shown to reduce this reflex.[3]

Chilblains are red and/or blue edematous plaques and papules that appear on the distal extremities that occur secondary to prolonged cold exposure. A variety of sensory symptoms such as itching or burning can accompany the skin changes.[1]

Frostnip is very similar to chilblains; however, instead of a red or blue appearance, it results in a white appearance. Frostnip is caused by exposure to cold/damp conditions and is seen with the beginning stages of Hunter’s Reflex, which is vasoconstriction of the extremities to help maintain core temperature.[1]

In frostbite, cold exposure is so extreme that the tissue actually freezes. Frostbite has two phases, the freezing of the tissue and the reperfusion phase. During the reperfusion phase, fluids — the arachidonic acid cascade, prostaglandin and thromboxanes — all cause changes that can lead to platelet aggregation and more vasoconstriction.[1,4] This can ultimately result in hemorrhagic blisters and dry gangrene. Frostbite is graded just like burns: 1st and 2nd degrees involve the dermis, 3rd degree reaches into the subcutaneous tissue, and 4th degree involves muscle and/or bone. If treating personnel are unfamiliar with the management of frostbite, early transfer to the proper center is critical.[1,2,5]

Hypothermia: [1,2,4,5]

Treatment for Hypothermic Injuries:
Rapid rewarming in warm water (37-39° Celcius) is ideal for the frostbite injuries.[2,4] Whatever you do, do not rewarm if the area has potential to refreeze, as the results can be devastating.[5] Analgesics are necessary, as rewarming is a very painful process.[2,4] Affected areas are tetanus-prone, so vaccination status should be assessed and Tdap should be given if necessary.[1,4] Debridement of blisters should occur only after the final demarcation is present. However, injuries are likely to expand.[2,4] There are limited studies suggesting that TPA may have benefits.[6] The coagulation process can be altered due to loss of enzyme function at lower temperature.[1] For hypothermia alone, several rewarming approaches exist, including passive, active non-invasive and active invasive strategies. Passive rewarming is good for mild hypothermia.[4,5] Shivering is thought to be beneficial as it helps raise the temperature more quickly.[1] Do not place warm saline bags on the body, as this can lead to burns. Active non-invasive techniques include water bath, bair huggers and humidified air.[1,4] Finally, active invasive warming includes lavages and ECMO.[1,4,5,7] The key is to raise temperature above 30° degrees Celsius.[1,4]

1) A 24-year-old male with no PMH jumped into the cold water. His heart rate subsequently slowed due to

A. Partially freezing of the heart
B. Contact of the cold water with his face
C. Prior drug abuse
D. Cushing’s response from cerebral edema
E. Sepsis from exposure to cold

2) After successfully resuscitating a gentleman stranded in a car from mild hyperthermia, you note that his hands have clear blisters and the left index finger is turning purple. Your treatment plan for this patient is:

A. Debridement of clear blisters only, wrap in xeroform gauze and discharge with close follow up
B. Debridement of clear blisters, wrap in xeroform gauze and admit for observation
C. Debridement of clear and hemorrhagic blisters, wrap in xeroform gauze and discharge with follow up
D. Debridement of clear and hemorrhagic blisters, wrap in xeroform gauze and admit for observation
E. Transfer to the nearest burn center

Answers: B and E


  1. Tintinalli JE. Tintinalli’s emergency medicine: A comprehensive study guide. McGraw Hill; 2011: Section 16.
  2. Knoop K. Environmental conditions. In:Atlas of emergency medicine 3rd ed. New York: McGraw Hill; 2010.
  3. Wittmers LE Jr, Pozos RS, Fall G, Beck L. Cardiovascular responses to face immersion (the diving reflex) in human beings after alcohol consumption. Ann Emerg Med. 1987 Sep;16(9):1031-6.
  4. Reichman E. Emergency medicine procedures; 2012: Chapter 189 Hypothermia Patient Management.
  5. Stone GK, Bowers,R. Current diagnosis and treatment. McGraw Hill; 2011:Chapter 46 Disorders Due to Physical and Environmental Agents.
  6. Johnson AR, Jensen HL, Peltier G, DelaCruz E. Efficacy of intravenous tissue plasminogen activator in frostbite patients and presentation of a treatment protocol for frostbite patients. 2011 Dec;4(6):344-8. doi: 10.1177/1938640011422596. Epub 2011 Sep 30.
  7. Turtiainen J, Halonen J, Syväoja S, Hakala T1.Rewarming a patient with accidental hypothermia and cardiac arrest using thoracic lavage.Ann Thorac Surg. 2014 Jun;97(6):2165-6. doi: 10.1016/j.athoracsur.2013.08.028.