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Hypothermia

Written by Ada’s Medical Knowledge Team

Updated on

What is hypothermia?

Hypothermia is when the body’s core temperature drops below 35 degrees Celsius or 95 degrees Fahrenheit. It is a life-threatening condition and if suspected as a diagnosis, medical attention should be sought immediately. People in specific age ranges (very young or elderly) are at increased risk. The causes vary from prolonged outdoor activities in a cold environment, exposure to cold water, insufficient indoor heating, and some medical conditions and medication.

Generally, the lower the body temperature is, the more serious the condition is for the person affected. However, symptoms vary from person to person. They can include shivering, pale skin, confusion, and many more. For a correct diagnosis, the body core temperature must be measured professionally. Laboratory tests are necessary to check for complications. Treatment for hypothermia revolves around warming up the affected person. Steps to keeping the affected person warm before an ambulance arrives include covering them in blankets and blocking them from the wind.

When hypothermia is caused by exposure to cold temperatures, the best approach to avoiding it is to keep warm. To ensure warmth, preparation is required, such as choosing appropriate clothing if the forecast predicts cold weather and having a well-heated and insulated home. [^1], [^2], [^5], [^6], [^7], [^8]

If you think that you might have hypothermia, you can try using Ada to find out more about your symptoms.

If hypothermia is suspected, seek medical attention immediately.

What are the causes of hypothermia?

Hypothermia is caused by the body losing more heat than it is producing. There are four major ways the body can lose heat, which are: [^2]

radiation

  • heat loss in the surrounding atmosphere

conduction

  • heat loss to an object or surface that is cooler than the body

convection

  • heat loss caused by air or wind passing across the skin

evaporation

  • when sweat evaporates on the skin.

In the majority of cases, hypothermia is caused by convective heat loss to cold air or by conductive heat loss to water.

Factors that can cause hypothermia include: [^2], [^6], [^8], [^10], [^11]

Primary Hypothermia hypothermia from environmental exposure

  • prolonged outdoor activities in cold climate
  • not wearing adequate clothing or wearing wet clothing
  • living in a poorly-heated home
  • falling into cold water

people particularly at risk of this:

  • homeless people
  • people under the influence of alcohol or drugs
  • elderly people
  • babies and young children

Secondary Hypothermia hypothermia caused by an underlying condition or medication

medical conditions, such as:

__Good to know: __

Newborn babies have less control over the regulation of heat in their bodies compared to the general population. This is especially true of smaller newborns, such as those born prematurely or who are underweight. Medical professionals will generally take several steps to ensure that a child is kept warm after birth to prevent hypothermia from developing. These steps can include making sure that the birthing room temperature is above 25 degrees Celsius (77 degrees Fahrenheit) and by wrapping babies in warmed blankets immediately after birth. [^3], [^4], [^12]

What are the symptoms of hypothermia?

__Hypothermia can progress through different stages of severity: __[^2]

  • mild hypothermia – core temperature around 32 to 35°C (90 to 95°F)
  • moderate hypothermia – core temperature around 28 to 32°C (82 to 90°F)
  • severe/profound hypothermia – core temperature below 28ºC (82°F).

However, symptoms of hypothermia may vary from person to person and accurate temperature measurements can be challenging. That’s why there is a large overlap between the different stages. In most cases, the symptoms of each particular stage include: [^2], [^5], [^6], [^9]

cold stressed

  • temperature not hypothermic yet
  • shivering
  • no signs of impaired mental or physical functioning

mild hypothermia

  • still conscious but potential signs of confusion
  • shivering
  • not able to care for self

moderate hypothermia

  • decreased consciousness or even unconscious
  • shivering or no shivering

severe/profound hypothermia

  • unconscious
  • no shivering.

Other symptoms that may or may not occur during the conscious stages and can be noticed by witnesses include: [^2], [^5], [^6], [^9]

  • confusion
  • dizziness
  • chills
  • mood change
  • irritability
  • poor judgment
  • lassitude
  • paradoxical undressing
    • taking off clothing despite cold exposure
  • motions, like rocking
  • slurred speech
  • some loss of physical coordination
  • faster or slower heart beat
  • faster or slower breathing
  • loss of bladder control
  • signs of frostbite
    • a pale body that is cold when touched.

If you think that you might have hypothermia, you can try using Ada to find out more about your symptoms.

If hypothermia is suspected, seek medical attention immediately.

What is the diagnosis of hypothermia?

In order to recognize hypothermia and diagnose it correctly, the following is required: [^2]

  • report or evidence of prolonged exposure to cold temperatures
  • core temperature below 35ºC (95ºF) that is measured with a specific thermometer.

Additionally, other tests will be conducted to rule out complications of hypothermia and to monitor the affected person. Usually, clinicians will go through the following steps: [^1], [^2], [^5], [^6]

__patient history __

  • Is the person conscious or unconscious?
  • Are any witnesses or companions present?
  • How long has the person been exposed to cold?
  • Sufficient clothing?
  • Any alcohol or drug consumption?
  • Any underlying conditions?
  • Any medications?

__physical examination __

  • total-body survey - external appearance: Wet? Neglected? Malnourished?
  • Any signs of trauma?
  • Any signs of frostbite or local cold-related injury?
  • Any signs of hypothermia? (see above)
  • Any signs of underlying conditions?

core temperature test

  • necessary for correct diagnosis
  • requires a special thermometer - Most standard thermometers read only to a minimum of 34°C (93°F) and are therefore of no use.

The thermometer will be inserted either:

  • rectally
  • into the bladder
  • or into the esophagus via the mouth - most accurate method, particularly during rewarming - also method of choice in all severe hypothermia cases.

laboratory testing *crucial to pick up on complications as well as underlying *conditions, such as:

  • blood sugar levels
  • electrolyte levels
  • kidney function
  • blood count
  • clotting function
  • oxygen levels
  • others if certain underlying conditions, alcohol, medication, or drug use is suspected.

Further monitoring

  • electrocardiogram (ECG)
    • Hypothermic people are highly susceptible to heart arrhythmia.
  • chest radiograph
    • can reveal complications due to aspiration or impaired heart functioning.

__Good to know: __

Try to avoid any rough handling of the affected person – a hypothermic person’s heart is very sensitive to movement and can quickly become arrhythmic. [^2], [^5], [^6]

What is the treatment for hypothermia?

If hypothermia is suspected, emergency services should be contacted immediately. Both first-aid treatment and hospital treatment for hypothermia are geared towards warming up the affected person. The subsequent steps are as follows: [^1], [^2], [^5], [^6], [^10], [^14]

first aid

  • most important: call an ambulance immediately!

  • avoid any rough handling or movement of the affected person - excessive motion can cause heart arrhythmia

  • If the person is unconscious and does not breath: - start basic life support right away (provided you have learnt it).

  • If the person is still conscious or unconscious, yet breathing:

    • cover the person’s body in blankets/jackets and wait for the ambulance to arrive
    • if necessary, discourage the person from moving!

initial emergency treatment

  • Medical professionals will: - check the airways, breathing, and circulation - advanced life support is provided if necessary - additional steps may be: - inserting a tube to secure the airways - providing oxygen therapy - placing two venous accesses.

rewarming

  • There are three different kinds of methods depending on the stage of hypothermia: a) passive external rewarming

    • treatment of choice for mild hypothermia
    • wet clothing is removed
    • person is covered with blankets or other types of insulation
    • room temperature should be kept around 28°C (82°F).

    b) active external rewarming

    • Treatment option for moderate to severe hypothermia, includes a combination of:
    • warm blankets
    • heating pads
    • radiant heat
    • warm baths
    • application of warm air directly to the skin.

    c) active internal (core) rewarming - Treatment option for severe hypothermia, usually proceeding in a stepwise approach including: - heated IV infusions - warmed humidified oxygen - instilling warm fluids into the abdominal cavity - drawing blood, rewarming it externally, and then re- infusing it.

  • treatment of heart arrhythmia - It’s crucial there is continuous monitoring of the heart during rewarming until complete recovery.

  • treatment of underlying conditions - Essential if these are the cause

  • treatment of other local injuries - Additionally, the treatment of cold-induced injuries to the skin may be necessary - This includes: - application of the tetanus toxoid - pain medication - rewarming the affected skin areas in a warm water bath.

Can hypothermia be prevented?

The best way to avoid primary hypothermia is to keep as warm as possible. Most of the time, this comes down to preparation and being wary of cold environments.

Ways to protect yourself from the cold include: [^15], [^16], [^17], [^18]

Outside:

  • wear appropriate clothing, such as waterproof clothing if there is forecasted rain and wear multiple layers if it is cold
  • wear a hat, scarf, and gloves/mittens
  • avoid spending prolonged periods outside alone
  • go inside for breaks wherever possible
  • consume heated beverages and warm food.

Inside cold houses:

  • dress warmly inside on cold days, such as wearing socks and slippers
  • keep warm when sleeping
  • consume heated beverages and warm food
  • check on elderly friends regularly
  • try to ensure the house is warmed
  • shut off rooms that will not be used in the house.

Can hypothermia be prevented?

Prognosis for people with mild hypothermia is generally good if they obtain the right treatment. For more severe stages, the evidence is limited and conflicting regarding prognosis. [^2]

Generally, it can be said that prognosis is better: [^2], [^5], [^6]

  • the shorter hypothermia lasts
  • the milder the stage of hypothermia is
  • the earlier adequate treatment is obtained
  • circulation remains intact and no complications occur
  • there are no additional underlying conditions.

What are the complications of hypothermia?

Since hypothermia is a life-threatening condition, the list of potential complications is long. The most important ones include: [^5], [^6]

  • heart arrhythmias
  • low blood sugar levels
  • derailment of electrolyte levels
  • acute kidney failure
  • gastrointestinal disorders - paralysis of the gastrointestinal tract - ulcers of the mucosa - impairment of the liver - inflammation of the pancreas
  • tendency to bleed uncontrollably caused by impaired blood clotting
  • local injuries to the skin - blistering - necrosis
  • loss of bladder function.

If you think that you might have hypothermia, you can try using Ada to find out more about your symptoms.

If hypothermia is suspected, seek medical attention immediately.

[^1] AMBOSS. “Hypothermia and frostbite.” Accessed October 16, 2019. [^2] UpToDate. "Accidental hypothermia in adults." Accessed October 16, 2019. [^3] UpToDate. "Hypothermia in children: Clinical manifestations and diagnosis." Accessed October 16, 2019. [^4] UpToDate. "Hypothermia in children: Management." Accessed October 16, 2019. [^5] BMJ Best Practice. “Hypothermia." Accessed October 15, 2019. [^6] Medscape. “Hypothermia.” Accessed October 15, 2019. [^7] Medline Plus. “Hypothermia.” Accessed October 16, 2019. [^8] Centers for Disease Control and Prevention. "Winter Weather Frequently Asked Questions.” Accessed October 16, 2019. [^9] The National Institute for Occupational Safety and Health (NIOSH). "Cold Stress - Cold Related Illnesses.” Accessed October 16, 2019. [^10] RCEM Learning. “Hypothermia: management.” Accessed October 16, 2019. [^11] Drinkaware.co.uk. “Alcohol and cold weather.” Accessed October 16, 2019. [^12)] British Journal of Midwifery. “Hypothermia in the Newborn: An exploration of its cause, effect and prevention.” Accessed October 16, 2019. [^13] Singapore Medical Journal. “Therapeutic temperature management (TTM): post-resuscitation care for adult cardiac arrest, with recommendations from the National TTM Workgroup.” Accessed October 16, 2019. [^14] Wilderness Medical Society Practice Guidelines. “Wilderness Medical Society Practice Guidelines for the Out-of-Hospital Evaluation and Treatment of Accidental Hypothermia: 2014 Update.” Accessed October 16, 2019. [^15] Medline Plus. "How to prevent frostbite and hypothermia.” Accessed October 16, 2019. [^16] United States Department of Labor. "Tips to protect workers in cold environments.” Accessed October 16, 2019. [^17] National Institute on Aging. “Cold Weather Safety for Older Adults.” Accessed October 16, 2019. [^18] Minnesota Sea Grant. “Hypothermia Prevention: Survival in Cold Water.” Accessed October 16, 2019.

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