What are the stages of hypothermia. How does body temperature affect hypothermia symptoms. What are the common misconceptions about heat loss in hypothermia. How can you recognize and prevent hypothermia in various situations.

Understanding Hypothermia: When Body Temperature Drops Too Low

Hypothermia is a potentially life-threatening condition that occurs when the body’s core temperature falls below 35°C (95°F). This dangerous drop in temperature can happen in various environments, not just in extremely cold weather. The human body constantly strives to maintain a core temperature of around 37°C (98.6°F), but when heat loss exceeds heat generation, hypothermia can set in.

Contrary to popular belief, you don’t need to be exposed to sub-zero temperatures to risk hypothermia. Any environment where the temperature is lower than your body temperature can potentially lead to heat loss. This makes understanding the symptoms and causes of hypothermia crucial for everyone, regardless of climate or season.

The Four Ways Your Body Loses Heat: Understanding the Mechanisms

To comprehend how hypothermia occurs, it’s essential to understand the four primary ways the human body loses heat:

1. Conduction: This involves direct heat transfer from the body to a cooler object. For example, lying on a cold surface can quickly draw heat away from your body.
2. Convection: Air or liquid flow across the skin can rapidly draw off heat. Wind chill is a prime example of convective heat loss.
3. Radiation: The body naturally emits electromagnetic waves, distributing heat into the surrounding environment. Exposed skin in cold air can lead to significant heat loss through radiation.
4. Evaporation: When fluid on the skin turns to vapor, it draws heat away from the body. This is why wet or sweaty skin in cold conditions can be particularly dangerous.

Understanding these mechanisms can help you recognize situations where you might be at risk of hypothermia and take appropriate precautions.

The Body’s Natural Defenses Against Cold: Behavioral and Physiological Responses

When exposed to cold, the human body employs two types of responses to maintain its core temperature:

Behavioral Responses

• Seeking shelter or warmth
• Increasing physical activity to generate heat
• Putting on additional layers of clothing

Physiological Responses

• Shivering to generate heat through muscle activity
• Vasoconstriction, which redirects blood flow to vital organs
• Increased metabolism to produce more heat
• Piloerection (goosebumps) to create an insulating layer of air near the skin

When these natural defenses fail to maintain body temperature, hypothermia can develop.

Stages of Hypothermia: Recognizing the Signs and Symptoms

Hypothermia progresses through three distinct stages, each with its own set of symptoms. Recognizing these stages is crucial for timely intervention and treatment.

Mild Hypothermia (35°C to 32°C / 95°F to 89.6°F)

• Pale, cool skin due to vasoconstriction
• Numbness in extremities
• Sluggish responses and drowsiness
• Shivering
• Increased heart rate and breathing

Moderate Hypothermia (32°C to 28°C / 89.6°F to 82.4°F)

• Decreasing level of consciousness
• Urine incontinence
• Cessation of shivering
• Slowed heart rate, breathing rate, and low blood pressure

Severe Hypothermia (below 28°C / 82.4°F)

• Unconsciousness and unresponsiveness
• Slow, irregular heartbeat
• No pupillary response to light
• Rigid muscles
• Barely detectable pulse and respiratory effort

As body temperature continues to drop, the risk of cardiac arrest and death increases significantly. Prompt medical attention is crucial in cases of moderate to severe hypothermia.

Debunking Common Hypothermia Myths: Head Heat Loss and More

One persistent myth about hypothermia is that we lose more heat through our heads than any other part of the body. This misconception has led to the common advice of always wearing a hat in cold weather. However, the truth is more nuanced.

Heat loss occurs through any area of exposed skin, not just the head. An adult’s head typically accounts for about 10% of their total body surface area. If an equal area of skin elsewhere on the body were exposed, such as the abdomen, it would lose heat at a similar rate.

The reason we often feel cold when our heads are exposed is that the rest of our body is usually covered, making the head feel comparatively colder. Additionally, the scalp has a rich blood supply, which can contribute to noticeable heat loss when exposed.

Why the Head Covering Advice Is Still Relevant for Children

While the myth about head heat loss isn’t entirely accurate for adults, the advice to keep children’s heads covered in cold weather remains valid. This is due to the different body proportions in children, especially infants.

• At birth, a baby’s head makes up over 20% of their total surface area
• Children have a larger head-to-body ratio compared to adults
• Infants and young children have less effective thermoregulation

These factors combined make children more susceptible to heat loss through their heads, putting them at a higher risk of hypothermia if left uncovered in cold conditions.

Medical Conditions and Hypothermia: Understanding the Hidden Risks

While environmental factors are often the primary cause of hypothermia, certain medical conditions can increase the risk or even directly lead to a dangerous drop in body temperature. Understanding these conditions is crucial for prevention and early intervention.

Stroke and Immobility

A stroke can leave a person immobile and unable to seek warmth or generate heat through movement. This immobility, especially if the person is in a cool environment, can quickly lead to hypothermia.

Diabetes and Hypoglycemia

People with diabetes experiencing a hypoglycemic episode may become disoriented or lose consciousness. If this occurs in a cold environment, they may be unable to protect themselves from heat loss, increasing their risk of hypothermia.

Other Medical Conditions Associated with Hypothermia Risk

• Hypothyroidism: Reduced thyroid function can lower the body’s metabolic rate, decreasing heat production
• Malnutrition: Lack of proper nutrition can impair the body’s ability to regulate temperature
• Severe burns: Damage to large areas of skin can impair the body’s ability to regulate temperature
• Spinal cord injuries: Can affect the body’s ability to regulate temperature below the level of injury
• Certain medications: Some drugs can affect the body’s ability to regulate temperature or increase susceptibility to cold

For individuals with these conditions, extra precautions may be necessary to prevent hypothermia, even in environments that might not seem dangerously cold to others.

Preventing Hypothermia: Strategies for Different Environments

Preventing hypothermia involves understanding the risks in various environments and taking appropriate precautions. Here are some strategies for different scenarios:

Outdoor Activities in Cold Weather

• Dress in layers, with a waterproof outer layer
• Keep extremities covered (hands, feet, head)
• Stay dry and change out of wet clothing immediately
• Avoid overexertion that leads to excessive sweating
• Carry emergency supplies, including extra clothing and high-energy snacks

Water Activities

• Wear appropriate protective gear, such as wetsuits or drysuits
• Know the water temperature and limit exposure time accordingly
• Have a plan for quick exit and warming in case of accidental immersion
• Carry flotation devices to reduce the need for swimming, which accelerates heat loss

Indoor Environments

• Maintain adequate home heating, especially for vulnerable individuals
• Use extra blankets and warm clothing if heating is inadequate
• Check on elderly neighbors or relatives during cold spells
• Be aware of the risks of hypothermia even in seemingly “warm” indoor environments

Special Considerations for At-Risk Groups

• Elderly: Ensure proper home heating and regular check-ins during cold weather
• Infants and young children: Dress in layers and monitor closely in cold environments
• People with certain medical conditions: Work with healthcare providers to develop personalized prevention strategies

By understanding the risks and taking appropriate precautions, most cases of hypothermia can be prevented.

Treatment and First Aid for Hypothermia: What to Do in an Emergency

Recognizing and responding quickly to hypothermia can be life-saving. Here’s what to do if you suspect someone is suffering from hypothermia:

Immediate Actions

1. Call for emergency medical help
2. Move the person to a warm, dry area and remove any wet clothing
3. If outdoors, protect the person from the cold ground and wind
4. Monitor breathing and pulse; be prepared to perform CPR if necessary

Rewarming Techniques

• For mild hypothermia:
  • Provide warm, dry clothing or blankets
  • Offer warm, sweet beverages (avoid alcohol)
  • Use skin-to-skin contact under loose, dry layers of blankets or clothing
• For moderate to severe hypothermia:
  • Handle the person gently and minimize movement to prevent cardiac arrest
  • Apply warm, dry compresses to the center of the body – chest, neck, groin, and head
  • Do not attempt to rewarm the arms and legs, as this can cause shock
  • Do not use direct heat sources like hot water, a heating pad, or heat lamp

What to Avoid

• Don’t give alcohol, which can worsen heat loss
• Avoid rubbing or massaging the person, which can cause cardiac issues
• Don’t place the person in a hot bath, which can lead to shock

Remember, severe hypothermia is a medical emergency requiring professional treatment. These first aid measures are crucial while waiting for emergency services to arrive.

Long-Term Effects of Hypothermia: Understanding the Aftermath

While the immediate dangers of hypothermia are well-known, the potential long-term effects are often overlooked. Surviving a severe hypothermic event can have lasting impacts on an individual’s health and well-being.

Physical Effects

• Organ damage: Prolonged hypothermia can cause damage to the heart, kidneys, and liver
• Neurological issues: Brain damage can occur due to reduced oxygen supply during hypothermia
• Frostbite complications: Severe cold exposure often accompanying hypothermia can lead to tissue damage and potential amputations
• Increased susceptibility to cold: Some individuals may experience long-term changes in their ability to tolerate cold temperatures

Psychological Effects

• Post-traumatic stress disorder (PTSD): Surviving a life-threatening hypothermic event can lead to PTSD
• Anxiety and depression: The experience and recovery process can trigger mental health challenges
• Cognitive changes: In some cases, hypothermia can lead to lasting cognitive impairments

Recovery and Rehabilitation

Recovery from severe hypothermia can be a long process, often requiring:

• Physical therapy to regain strength and mobility
• Occupational therapy to relearn daily living skills
• Psychological counseling to address emotional trauma
• Regular medical check-ups to monitor organ function and overall health

Understanding these potential long-term effects underscores the importance of hypothermia prevention and prompt treatment. It also highlights the need for comprehensive care and support for those who have experienced severe hypothermia.

Hypothermia in Different Climates: Not Just a Cold Weather Problem

While hypothermia is often associated with freezing temperatures and snowy landscapes, it’s a misconception that it only occurs in cold climates. In fact, hypothermia can happen in a variety of environments, including those that might seem relatively warm.

Hypothermia in Temperate Climates

• Water-related risks: Even in mild weather, prolonged exposure to water below body temperature can lead to hypothermia
• Nighttime temperature drops: Cool nights, especially when combined with wind and moisture, can pose a risk
• Indoor environments: Inadequate heating or prolonged exposure to air conditioning can potentially lead to hypothermia in vulnerable individuals

Hypothermia in Tropical Climates

Yes, hypothermia can occur even in tropical regions. Some scenarios include:

• High-altitude areas: Mountainous regions in tropical countries can have cold temperatures
• Water activities: Prolonged time in water, even if it feels warm, can lead to hypothermia
• Air-conditioned environments: Excessive cooling, especially for people unused to it, can potentially cause hypothermia

Special Considerations for Different Climates

• Desert climates: Rapid temperature drops at night can catch people unprepared
• Humid climates: High humidity can make evaporative cooling less effective, masking the feeling of cold
• Coastal areas: The combination of wind and moisture can accelerate heat loss

Understanding that hypothermia is a risk in various climates emphasizes the need for awareness and preparedness regardless of location. It’s crucial to consider factors beyond just air temperature when assessing the risk of hypothermia.

Hypothermia – Better Health Channel

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Summary

Read the full fact sheet

• Hypothermia occurs when the body’s temperature falls below 35 °C.
• Hypothermia can occur in any situation where the body is losing more heat to the environment than it is generating.
• Severe hypothermia is life-threatening without prompt medical attention.

What is hypothermia?

Hypothermia occurs when the body’s temperature falls below 35 °C.

The human body has a number of systems that maintain a constant core temperature of around 37 °C. A person doesn’t have to be in sub zero temperatures to risk hypothermia – it only requires the environmental temperature to be less than the body temperature and a person will ’donate’ heat to the atmosphere.

If the heat generated by the body (people are constantly generating heat through metabolic processes and muscle movements) is less than that lost to the environment, then their temperature will begin to fall.

The 4 ways that the human body loses heat include:

• Conduction – by direct transfer from the body to an object that is cooler than the body (for example, lying on a cold surface will pass body warmth to the surface away from the body).
• Convection – air or liquid flow across the skin drawing off heat (for example, wind will increase heat loss, as will water that is cooler than body temperature).
• Radiation – electromagnetic waves distribute heat into the ambient environment (for example, exposed skin will allow heat to be drawn off if the air temperature is less than the body – the exposed head of a person is a strong source of heat loss, particularly in children).
• Evaporation – fluid on the skin turns to vapour, drawing off heat (moist skin will lose heat more rapidly, such as in someone who is wet, clammy or has exposed moist skin, such as burns).

Sometimes, medical conditions can lead to hypothermia. For example, someone experiencing a stroke or a person with diabetes having a hypoglycaemic episode may end up lying immobile for a period of time, unable to protect themselves from hypothermia.

The natural response to becoming cold is two-fold, including:

• Behavioural – the person will try and move around to generate heat, and seek shelter from further heat loss.
• Physiological – the body shunts blood to the core to keep it warm, hair stands on end to trap a layer of warm air around us (goose bumps), we shiver to make more heat and our body releases hormones to speed up our metabolism to create more heat.

If these measures don’t work, hypothermia will result.

Symptoms of hypothermia

Hypothermia can be distinguished into 3 stages – mild, moderate or severe. The signs and symptoms of hypothermia can be approximately grouped with the temperature ranges of the different stages:

For mild hypothermia (35 to 32^oC), signs and symptoms include:

• pale and cool to touch as blood vessels constrict in the skin
• numbness in the extremities
• sluggish responses, drowsiness or lethargic
• shivering
• increased heart rate and breathing.

For moderate hypothermia (32 to 28^oC), signs and symptoms include:

• decreasing conscious state
• urine incontinence as a result of an increased workload on the kidneys related to blood being shunted to the major organs
• no longer shivering
• slowed heart rate, breathing rate and low blood pressure.

For severe hypothermia (below 28^oC), signs and symptoms include:

• unconscious and no longer responding
• the heart beats more slowly and may become irregular before ultimately stopping if the person gets too cold
• no response to light in the pupil of the eye
• rigid muscles – the person might feel like they are in rigor mortis
• pulses and respiratory effort may be present but hard to detect.

Myth about hypothermia

One hypothermia myth is that you lose more heat through your head than any other part of your body. This is not true. Heat loss occurs through any area of skin exposed to the environment. An adult head is approximately 10% of the surface area of their whole body.

Most of the time, the rest of our bodies are covered, with the possible exception of our hands (which together only make up about 4% of our surface area), so we feel cold, because our head is cold compared to the rest of our insulated body.

If a person had to expose another part of their body – for example, their abdomen, which also makes up about 10% of an average adult body – then they would lose as much heat through that as their exposed head.

Parents are often advised to keep children’s heads covered to stop them getting cold, but this isn’t to do with any special heat-losing properties of the head. It has more to do with the relative size of the head to the body. At birth, a baby’s head makes up over 20% of their total surface area, so exposing that skin leads to increased heat loss, putting them at risk of hypothermia much quicker than an adult, if they were to both have their heads uncovered.

Risk factors for hypothermia

Factors that may increase a person’s susceptibility to hypothermia include:

• Children – small children are at risk of hypothermia because they are unable to protect themselves in varied environmental conditions. They also have a faster rate of heat loss than adults, generally speaking. Due to their large head relative to their body, covering their heads will prevent significant heat loss.
• Old age – in the elderly, the ability to notice changes in temperature is impaired due to the loss of nerve endings to the skin. They also have less fat, which has an insulating function, and a lower metabolic rate, and so generate less heat themselves. Social factors also play a part, as the elderly are more likely to be reluctant to use heating for economic reasons, and they may be socially isolated so can be alone for long periods of time with no one noticing as they deteriorate.
• Dementia or immobilising illness – anybody who is unable to look after themselves independently, either physically or cognitively, is at risk of hypothermia. People with dementia can be particularly at risk if they wander off in cold conditions without having protected themselves with appropriate clothing first.
• Alcohol and other drugs – alcohol makes people feel cosy because it relaxes the blood vessels, allowing more blood to flow near the skin, providing a flushed appearance and a warm sensation. This also puts people who are drunk at significant risk of hypothermia if they are outside in cold weather, as this increases the rate of heat loss. It also slows down the metabolism, so slows down internal heat generation. Alcohol also impairs judgement, so the person is less likely to recognise the environment and their own physical condition, and less likely to take protective measures against heat loss. This is also a concern with any other mind-altering substance.
• Water immersion – people who spend any time immersed in water that is colder than body temperature will suffer significant heat loss. The other person at risk is anyone who may have been in wet clothes for a prolonged period of time, either due to incontinence or sweating.

Severe hypothermia is life-threatening

Mild hypothermia (32 to 35°C body temperature) is usually easy to treat. However, the risk of death increases as the core body temperature drops below 32°C.

If core body temperature is lower than 28°C, the condition is life-threatening without immediate medical attention. Under this temperature, a person will be very cold to touch, unresponsive, rigid, not breathing, have no pulse, and their pupils will be fixed (they will not respond to light changes). They will appear to be dead, but they may not be.

First aid for severe hypothermia

First aid steps for severe hypothermia include:

• In an emergency, call triple zero (000).
• While waiting for help to arrive, monitor the person’s breathing. If they have severe hypothermia, their breathing may become dangerously slow or shallow, or they may cease breathing.
• Begin cardiopulmonary resuscitation (CPR) immediately if the person shows no signs of life – if they are not breathing normally, are unconscious or unresponsive, or not moving.

Never assume a person is dead. A person with severe hypothermia may only take one breath per minute, with a heart rate of less than 20 beats per minute. Always assume they are alive.

First aid for all cases of hypothermia

The first aid tips that apply to all stages of hypothermia include:

• The first step in all cases of hypothermia is to prevent any further heat loss. This is done by removing the 4 ways that heat loss occurs, including:
  • Conduction – remove the person from a cold surface if possible. Ideally, place them onto a warm surface, or at least a dry one that will prevent further heat loss.
  • Convection – remove the person from a windy or wet environment. Covering with blankets is good, but the aim must be to get them to shelter.
  • Radiation – cover as much of the person as possible to avoid radiant heat loss. Particularly cover the head of a younger child.
  • Evaporation – wet and sweaty people will suffer evaporative heat loss. Dry skin where possible and remove wet clothing as soon as practicable.
• Don’t massage or rub the person – and do not allow them to help you. Keep them still because, particularly below 32^oC, they risk a cardiac arrest.
• Move the person out of the cold – if this is not possible, protect them from wind, cover their head and insulate their body from the cold ground. If the person is moderately or severely hypothermic, move them as gently as possible. Below approximately 30^oC the heart is very vulnerable and there are case studies of simple movements like rolling the person over prompting a cardiac arrest.
• Remove wet clothing – replace with a dry covering, preferably warm. Cover the person’s head.
• Try to warm the person – do not use hot water immersion. Make sure that the person is dry. Insulate them from the environment to retain whatever heat they are producing. Use whatever heat source is available – heaters, hot water bottles, heat packs, an electric blanket – to begin slowly warming the person. The heat source should not be too hot or too close to the person. A slow and gradual warming is ideal and whatever heat source is used only has to be warmer than the person to be donating heat. When applying heat close to the skin – such as with hot water bottles or heat packs – be careful not to make them too hot, as the person may have impaired sensation to their skin and is at risk of suffering burns. If using multiple small sources of heat, such as heat packs, preferentially pack them around the torso, into armpits and the groin to focus warming on the central area. Share body heat – to warm the person’s body, remove your clothing and lie next to the person, making skin-to-skin contact. Then cover both bodies with a blanket or get into a sleeping bag if possible.
• Don’t give alcohol – it lowers the body’s ability to retain heat. If the person is alert and is able to swallow, have them drink warm, non-alcoholic beverages. Do not offer liquids if they are vomiting.
• Do not leave the person alone – stay with them at all times.
• Continually monitor breathing – if the person’s breathing stops, start cardiopulmonary resuscitation (CPR) immediately if you are trained. If unsure, dial triple zero (000). The operators will advise you what to do. Continue CPR until the person starts breathing on their own or until medical help arrives.
• Don’t assume the person is dead – CPR can be lifesaving for a person with severe hypothermia who may appear to be dead. They may not be breathing, have no pulse, be cold to touch, have fixed pupils and be rigid, but they may still be alive.

Preventing hypothermia when outdoors

Exposure to cold weather, even for a short time, can be dangerous if you are not prepared. Shivering and feeling cold or numb are warning signs that the body is losing too much heat.

Simple ways to prevent hypothermia include:

• Avoid prolonged exposure to cold weather.
• Be alert to weather conditions that may increase the risk of hypothermia and act accordingly. For example, seek shelter during a snowstorm.
• If driving through a cold weather environment, particularly if there is a risk of ice or snow on the road increasing the chances of a crash, do not rely on the vehicle heater to stay warm while driving. Dress for the weather outside the car and leave the heater turned down so that in the event that you are incapacitated by an accident or snowstorm, you have a better chance of avoiding hypothermia.
• Wear several layers of clothing to trap body heat, rather than just one bulky layer. Natural fibres like wool are better at holding heat.
• Use a weatherproof outer layer to stay dry.
• Use gloves, scarves and socks, with spares to replace when wet.
• Wear insulated boots.
• Wear warm headgear.
• Make sure your clothes and boots aren’t too tight. If your blood circulation is restricted, you are more prone to hypothermia.
• Drink plenty of fluids.
• Eat regularly.
• Take regular breaks to reduce the risk of physical fatigue.
• Keep your eye on exact body temperature by taking a clinical thermometer in your first aid kit.
• Change out of wet clothes straight away.
• Avoid alcohol, cigarettes and caffeine.
• Make sure your kit includes a good supply of waterproof matches.

Use a buddy system

When participating in any outdoor activity that has the potential risk of hypothermia, such as bushwalking or mountaineering, use the ‘buddy system’ and check each other for warning signs. You may not be able to recognise your own symptoms of hypothermia due to mental confusion. First aid training is strongly advised.

Hypothermia at home

Hypothermia can occur in the home. The elderly and some people with medical conditions are more susceptible to hypothermia. The risk can be reduced by:

• making sure there is adequate heat in the home
• seeking assistance from government agencies for help with heating, food and clothing if necessary
• having regular medical check-ups.

Where to get help

• In an emergency, always call triple zero (000)
• Your GP (doctor)
• Hospital emergency department

• HypothermiaExternal Link, St John Ambulance Australia.

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Reviewed on: 25-10-2022

Hypothermia – Better Health Channel

Actions for this page

Summary

Read the full fact sheet

• Hypothermia occurs when the body’s temperature falls below 35 °C.
• Hypothermia can occur in any situation where the body is losing more heat to the environment than it is generating.
• Severe hypothermia is life-threatening without prompt medical attention.

What is hypothermia?

Hypothermia occurs when the body’s temperature falls below 35 °C.

The human body has a number of systems that maintain a constant core temperature of around 37 °C. A person doesn’t have to be in sub zero temperatures to risk hypothermia – it only requires the environmental temperature to be less than the body temperature and a person will ’donate’ heat to the atmosphere.

If the heat generated by the body (people are constantly generating heat through metabolic processes and muscle movements) is less than that lost to the environment, then their temperature will begin to fall.

The 4 ways that the human body loses heat include:

• Conduction – by direct transfer from the body to an object that is cooler than the body (for example, lying on a cold surface will pass body warmth to the surface away from the body).
• Convection – air or liquid flow across the skin drawing off heat (for example, wind will increase heat loss, as will water that is cooler than body temperature).
• Radiation – electromagnetic waves distribute heat into the ambient environment (for example, exposed skin will allow heat to be drawn off if the air temperature is less than the body – the exposed head of a person is a strong source of heat loss, particularly in children).
• Evaporation – fluid on the skin turns to vapour, drawing off heat (moist skin will lose heat more rapidly, such as in someone who is wet, clammy or has exposed moist skin, such as burns).

Sometimes, medical conditions can lead to hypothermia. For example, someone experiencing a stroke or a person with diabetes having a hypoglycaemic episode may end up lying immobile for a period of time, unable to protect themselves from hypothermia.

The natural response to becoming cold is two-fold, including:

• Behavioural – the person will try and move around to generate heat, and seek shelter from further heat loss.
• Physiological – the body shunts blood to the core to keep it warm, hair stands on end to trap a layer of warm air around us (goose bumps), we shiver to make more heat and our body releases hormones to speed up our metabolism to create more heat.

If these measures don’t work, hypothermia will result.

Symptoms of hypothermia

Hypothermia can be distinguished into 3 stages – mild, moderate or severe. The signs and symptoms of hypothermia can be approximately grouped with the temperature ranges of the different stages:

For mild hypothermia (35 to 32^oC), signs and symptoms include:

• pale and cool to touch as blood vessels constrict in the skin
• numbness in the extremities
• sluggish responses, drowsiness or lethargic
• shivering
• increased heart rate and breathing.

For moderate hypothermia (32 to 28^oC), signs and symptoms include:

• decreasing conscious state
• urine incontinence as a result of an increased workload on the kidneys related to blood being shunted to the major organs
• no longer shivering
• slowed heart rate, breathing rate and low blood pressure.

For severe hypothermia (below 28^oC), signs and symptoms include:

• unconscious and no longer responding
• the heart beats more slowly and may become irregular before ultimately stopping if the person gets too cold
• no response to light in the pupil of the eye
• rigid muscles – the person might feel like they are in rigor mortis
• pulses and respiratory effort may be present but hard to detect.

Myth about hypothermia

One hypothermia myth is that you lose more heat through your head than any other part of your body. This is not true. Heat loss occurs through any area of skin exposed to the environment. An adult head is approximately 10% of the surface area of their whole body.

Most of the time, the rest of our bodies are covered, with the possible exception of our hands (which together only make up about 4% of our surface area), so we feel cold, because our head is cold compared to the rest of our insulated body.

If a person had to expose another part of their body – for example, their abdomen, which also makes up about 10% of an average adult body – then they would lose as much heat through that as their exposed head.

Parents are often advised to keep children’s heads covered to stop them getting cold, but this isn’t to do with any special heat-losing properties of the head. It has more to do with the relative size of the head to the body. At birth, a baby’s head makes up over 20% of their total surface area, so exposing that skin leads to increased heat loss, putting them at risk of hypothermia much quicker than an adult, if they were to both have their heads uncovered.

Risk factors for hypothermia

Factors that may increase a person’s susceptibility to hypothermia include:

• Children – small children are at risk of hypothermia because they are unable to protect themselves in varied environmental conditions. They also have a faster rate of heat loss than adults, generally speaking. Due to their large head relative to their body, covering their heads will prevent significant heat loss.
• Old age – in the elderly, the ability to notice changes in temperature is impaired due to the loss of nerve endings to the skin. They also have less fat, which has an insulating function, and a lower metabolic rate, and so generate less heat themselves. Social factors also play a part, as the elderly are more likely to be reluctant to use heating for economic reasons, and they may be socially isolated so can be alone for long periods of time with no one noticing as they deteriorate.
• Dementia or immobilising illness – anybody who is unable to look after themselves independently, either physically or cognitively, is at risk of hypothermia. People with dementia can be particularly at risk if they wander off in cold conditions without having protected themselves with appropriate clothing first.
• Alcohol and other drugs – alcohol makes people feel cosy because it relaxes the blood vessels, allowing more blood to flow near the skin, providing a flushed appearance and a warm sensation. This also puts people who are drunk at significant risk of hypothermia if they are outside in cold weather, as this increases the rate of heat loss. It also slows down the metabolism, so slows down internal heat generation. Alcohol also impairs judgement, so the person is less likely to recognise the environment and their own physical condition, and less likely to take protective measures against heat loss. This is also a concern with any other mind-altering substance.
• Water immersion – people who spend any time immersed in water that is colder than body temperature will suffer significant heat loss. The other person at risk is anyone who may have been in wet clothes for a prolonged period of time, either due to incontinence or sweating.

Severe hypothermia is life-threatening

Mild hypothermia (32 to 35°C body temperature) is usually easy to treat. However, the risk of death increases as the core body temperature drops below 32°C.

If core body temperature is lower than 28°C, the condition is life-threatening without immediate medical attention. Under this temperature, a person will be very cold to touch, unresponsive, rigid, not breathing, have no pulse, and their pupils will be fixed (they will not respond to light changes). They will appear to be dead, but they may not be.

First aid for severe hypothermia

First aid steps for severe hypothermia include:

• In an emergency, call triple zero (000).
• While waiting for help to arrive, monitor the person’s breathing. If they have severe hypothermia, their breathing may become dangerously slow or shallow, or they may cease breathing.
• Begin cardiopulmonary resuscitation (CPR) immediately if the person shows no signs of life – if they are not breathing normally, are unconscious or unresponsive, or not moving.

Never assume a person is dead. A person with severe hypothermia may only take one breath per minute, with a heart rate of less than 20 beats per minute. Always assume they are alive.

First aid for all cases of hypothermia

The first aid tips that apply to all stages of hypothermia include:

• The first step in all cases of hypothermia is to prevent any further heat loss. This is done by removing the 4 ways that heat loss occurs, including:
  • Conduction – remove the person from a cold surface if possible. Ideally, place them onto a warm surface, or at least a dry one that will prevent further heat loss.
  • Convection – remove the person from a windy or wet environment. Covering with blankets is good, but the aim must be to get them to shelter.
  • Radiation – cover as much of the person as possible to avoid radiant heat loss. Particularly cover the head of a younger child.
  • Evaporation – wet and sweaty people will suffer evaporative heat loss. Dry skin where possible and remove wet clothing as soon as practicable.
• Don’t massage or rub the person – and do not allow them to help you. Keep them still because, particularly below 32^oC, they risk a cardiac arrest.
• Move the person out of the cold – if this is not possible, protect them from wind, cover their head and insulate their body from the cold ground. If the person is moderately or severely hypothermic, move them as gently as possible. Below approximately 30^oC the heart is very vulnerable and there are case studies of simple movements like rolling the person over prompting a cardiac arrest.
• Remove wet clothing – replace with a dry covering, preferably warm. Cover the person’s head.
• Try to warm the person – do not use hot water immersion. Make sure that the person is dry. Insulate them from the environment to retain whatever heat they are producing. Use whatever heat source is available – heaters, hot water bottles, heat packs, an electric blanket – to begin slowly warming the person. The heat source should not be too hot or too close to the person. A slow and gradual warming is ideal and whatever heat source is used only has to be warmer than the person to be donating heat. When applying heat close to the skin – such as with hot water bottles or heat packs – be careful not to make them too hot, as the person may have impaired sensation to their skin and is at risk of suffering burns. If using multiple small sources of heat, such as heat packs, preferentially pack them around the torso, into armpits and the groin to focus warming on the central area. Share body heat – to warm the person’s body, remove your clothing and lie next to the person, making skin-to-skin contact. Then cover both bodies with a blanket or get into a sleeping bag if possible.
• Don’t give alcohol – it lowers the body’s ability to retain heat. If the person is alert and is able to swallow, have them drink warm, non-alcoholic beverages. Do not offer liquids if they are vomiting.
• Do not leave the person alone – stay with them at all times.
• Continually monitor breathing – if the person’s breathing stops, start cardiopulmonary resuscitation (CPR) immediately if you are trained. If unsure, dial triple zero (000). The operators will advise you what to do. Continue CPR until the person starts breathing on their own or until medical help arrives.
• Don’t assume the person is dead – CPR can be lifesaving for a person with severe hypothermia who may appear to be dead. They may not be breathing, have no pulse, be cold to touch, have fixed pupils and be rigid, but they may still be alive.

Preventing hypothermia when outdoors

Exposure to cold weather, even for a short time, can be dangerous if you are not prepared. Shivering and feeling cold or numb are warning signs that the body is losing too much heat.

Simple ways to prevent hypothermia include:

• Avoid prolonged exposure to cold weather.
• Be alert to weather conditions that may increase the risk of hypothermia and act accordingly. For example, seek shelter during a snowstorm.
• If driving through a cold weather environment, particularly if there is a risk of ice or snow on the road increasing the chances of a crash, do not rely on the vehicle heater to stay warm while driving. Dress for the weather outside the car and leave the heater turned down so that in the event that you are incapacitated by an accident or snowstorm, you have a better chance of avoiding hypothermia.
• Wear several layers of clothing to trap body heat, rather than just one bulky layer. Natural fibres like wool are better at holding heat.
• Use a weatherproof outer layer to stay dry.
• Use gloves, scarves and socks, with spares to replace when wet.
• Wear insulated boots.
• Wear warm headgear.
• Make sure your clothes and boots aren’t too tight. If your blood circulation is restricted, you are more prone to hypothermia.
• Drink plenty of fluids.
• Eat regularly.
• Take regular breaks to reduce the risk of physical fatigue.
• Keep your eye on exact body temperature by taking a clinical thermometer in your first aid kit.
• Change out of wet clothes straight away.
• Avoid alcohol, cigarettes and caffeine.
• Make sure your kit includes a good supply of waterproof matches.

Use a buddy system

When participating in any outdoor activity that has the potential risk of hypothermia, such as bushwalking or mountaineering, use the ‘buddy system’ and check each other for warning signs. You may not be able to recognise your own symptoms of hypothermia due to mental confusion. First aid training is strongly advised.

Hypothermia at home

Hypothermia can occur in the home. The elderly and some people with medical conditions are more susceptible to hypothermia. The risk can be reduced by:

• making sure there is adequate heat in the home
• seeking assistance from government agencies for help with heating, food and clothing if necessary
• having regular medical check-ups.

Where to get help

• In an emergency, always call triple zero (000)
• Your GP (doctor)
• Hospital emergency department

• HypothermiaExternal Link, St John Ambulance Australia.

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Reviewed on: 25-10-2022

What is hypothermia? Symptoms and first aid for hypothermia and frostbite

• Blog
• Hypothermia – symptoms, first aid for hypothermia and frostbite

Contents

• Symptoms of hypothermia
• 1. Mild
• 2. Moderate
• 3. Severe
• First aid for hypothermia 9 0005
• First aid for hypothermia
• First aid for frostbite
• Prevention of hypothermia
• 1. Passive protection against cold
• 2. Active heat replenishment.

Hypothermia is a critical hypothermia of the body, when the body temperature drops to 35 ° C and below. Severe hypothermia leads to cardiac arrest and death. Hypothermia occurs imperceptibly, with a decrease in body temperature by 1-2 degrees, even during movement and physical work. Below we will consider how to detect it in time and provide assistance.

Symptoms of hypothermia

The main cause of hypothermia is the loss of heat in the cold through the skin and breathing. The protective program turns on – the mechanism of thermoregulation. The body saves important organs by sacrificing skin, fingers and toes, nose – without this, a person can survive.

Hypothermia is divided into three stages:

1.

Mild

The temperature drops to the first critical level of 35-34 °C. Trembling appears – the release of heat through muscle activity. Vessels narrow – the skin turns pale. At this stage, it is easy to get frostbite. The metabolism slows down, so a person feels lethargy, apathy, and critical thinking suffers. Symptoms of mild hypothermia include memory problems, the person does not remember where or where they are going. If hypothermia begins in nature at this point, it is easy to lose sight of your bearings. Hunger and fatigue exacerbate the symptoms.

2. Moderate

Body temperature drops to 30°C. The pulse is weak – the heart slows down to keep warm and protect the brain. The skin becomes cold, bloodless – a characteristic marble shade. The limbs are hard to bend. Metabolism and chemical reactions in the nervous system are disturbed. Disturbances of consciousness progress – severe drowsiness, speech disorders, hallucinations sometimes begin.

3. Severe

Low temperature, up to 27 °C and below. The person loses consciousness, the limbs become stiff, severe frostbite. The pulse practically disappears – you can feel it on the carotid artery. Breathing problems begin – rare and intermittent. At this stage, the pupils do not react to light, the heart may stop.

The first companion of hypothermia is frostbite of the extremities. There is a spasm of capillaries, the tissues do not receive enough oxygen and nutrition. The process occurs at different stages of supercooling. Negative consequences increase:

• hunger and overwork;
• immobile or uncomfortable position;
• tight footwear;
• wet clothes;
• immunosuppressed;
• vascular disease;
• mechanical damage;
• blood loss;
• alcohol intoxication.

Hypothermia First Aid

If the casualty shows signs of hypothermia, the goal of first aid is to stop heat loss. At all stages of hypothermia or frostbite, a hot bath or shower is prohibited. The patient should not be brought into a hot room, rubbed with snow and given alcohol.

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First aid for hypothermia

Conditions are created so that the body can warm up – they pull the victim out of the water or snow, leave a cold room or open area.

1. Warm the patient.
2. Remove wet clothing, pay special attention to shoes.
3. Cover with a warm blanket, put a heating pad, warm with your body or arrange another source of heat.
4. If possible, organize a warm bath or shower. Raise the temperature of the water gradually, at first barely warm. So that a sharp increase in blood circulation does not destroy the vessels. The water is gradually brought to 40 °C. It is necessary to take a bath until the body temperature rises to the stage of mild hypothermia – 34 ° C
5. In case of severe hypothermia, first aid is not enough. You need to call a doctor or take the victim to the hospital.

Frostbite First Aid

1. It is necessary to remove the patient from the frost, gradually warm the frostbitten area, rub it with your hand until it turns red. This is done carefully, increasing pressure gradually so as not to damage the vessels. After giving the patient a warm, not hot drink.
2. When sensation returns to the limbs, the victim feels pain in the affected area, it is necessary to prepare an anesthetic in advance.
3. Next, the limb is wrapped in a warm cloth and fixed in a sling to reduce swelling. With severe frostbite, the patient is taken to the hospital. Before this, the patient is carefully insulated.
4. Do not put frostbitten hands on the battery, other hot surfaces, rub with snow, grease.

Prevention of hypothermia

Protective measures are divided into two stages:

1. Passive protection against cold – removes moisture from the skin.

The best option is thermal underwear.

2. Active heat recovery.

Food will help replenish heat in the body, it is better to choose high-calorie portions, have a hearty lunch before going out. Thermos with warm drink will not let you freeze. You don’t feel thirsty in the cold, so it’s easier to get dehydrated than in the heat, and the lack of water in the body increases the symptoms of hypothermia.

An external heat source is the easiest way to keep warm. When walking around the city, you need to pause and go into the premises. A suitable option is thermochemical and electric heating pads.

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symptoms and causes, stages. How to treat?

1. Causes of Hypothermia

2. Temperature control processes

3. Symptoms and stages of hypothermia

4. Diagnosis of hypothermia

5. First aid

Image by prostooleh on Freepik

Temperature is an important health indicator. Critical hypothermia of the body with a decrease in temperature below 35 ° C is called hypothermia. Typical symptoms are tremors, confusion, changes in breathing and pulse rate, blue lips, fingers and toes.

Causes of hypothermia

Hypothermia as a process of heat transfer disorders occurs when the body loses more heat than it produces. The rate of metabolism and adaptive response is regulated by hormones produced in the adrenal and thyroid glands.

There are two mechanisms of body heat production: obligatory and additional. Mandatory occurs against the background of the physiological processes of the body. The generated heat is enough to maintain a normal temperature, provided that the body is in comfortable temperature conditions from +18°С to +22°С. An additional one is activated when the ambient temperature is outside the comfort range. It consists of two types of thermogenesis:

• Non-contractile. The human body contains brown fat, which feeds on blood. It also contains mitochondria, tiny energy cells. Due to their internal combustion, many calories are burned and heat is released. This process is known as thermogenesis. Babies have the most brown fat. This is necessary to create a natural protection against the cold. Adults also have it, but in a much smaller ratio. Brown fat is located between the shoulder blades, on the neck, in the region of the kidneys.

• Contractile. Trembling (tremor) in the body occurs due to muscle tone, this is an uncontrolled process and the body’s defense against hypothermia.

Temperature control processes

The ability to maintain a constant body temperature around 37°C is called thermoregulation. The control center is located in the hypothalamus. The so-called target temperature value is also set here. Each part of the body is equipped with a temperature “sensor” (receptor) that signals temperature fluctuations.

From the point of view of creating comfortable temperature conditions, the vital organs occupy a dominant place, and the skin and limbs – according to the residual principle. Under conditions of moderate hypothermia, to reduce heat loss over a large area, heat is spent primarily on internal organs. The skin temperature may differ from the internal temperature, the fluctuation is up to 9 ° C.

The temperature range perceived by the body as pleasant does not require large expenditures for thermoregulation and can only be maintained at a constant level due to blood circulation in the skin. This state is called the temperature of indifference. It is 28-30 ° C, provided that the calculated values ​​​​are taken for a person without clothes at rest and with average air humidity. For a dressed person, this parameter drops to 22 ° C.

Body temperature is an individual parameter. In children, it is always slightly increased due to activity and intensive metabolism. In the elderly, the temperature may be below normal – 34-35 degrees Celsius, which is due to the speed of chemical reactions.

There are peripheral and central temperatures. Peripheral (surface) – the temperature of the skin. Measured on the forehead and in the armpits. Central – fixes the temperature of internal organs and large vessels, keeps at the level of 36.1-38.2 degrees Celsius. Areas for measurement – rectum, mouth, esophagus, nasopharynx, bladder.

Symptoms and stages of hypothermia

The state of hypothermia slows down all physiological functions, including the cardiovascular and respiratory systems, nerve conduction velocity, mental acuity, neuromuscular reaction time, and metabolic rate. Thermoregulation stops at a temperature just below 30 0C, then the body is completely dependent on external heat sources.

At first, severe shivering occurs, which subsides at temperatures below 310C, which contributes to an even faster drop in body temperature. The dysfunction of the central nervous system progresses as the body temperature decreases, the person ceases to feel cold. Lethargy, drowsiness, clumsiness are replaced by confusion, irritability, sometimes hallucinations and, finally, coma. Breathing and heartbeat slow down, and eventually stop altogether.

There are three stages of hypothermia:

• Stage 1 – “light hypothermia.” The temperature is 32-36 ° C, the body tries to maintain a constant internal temperature, releasing heat due to muscle tremors. At the same time, vasoconstriction occurs on the periphery, which reduces heat dissipation in the extremities.

• Stage 2 – “moderate hypothermia”. When the temperature drops to 28-32 ° C, there is an increasing loss of consciousness and a transition from a sleepy state to a soporous or coma state. It flows smoothly. Protective reflexes are reduced, and the release of heat stops. The Glasgow Coma Scale is recommended for an accurate assessment of a person’s condition.

• 3rd stage – “severe hypothermia.” If the temperature drops below 28 °C, complete loss of consciousness occurs. The pulse decreases, blood pressure drops, asystole, rigid pupils, muscle paralysis occur.

Hypothermia diagnosis

• Measurement of internal body temperature. If victims are unconscious, body temperature (in the rectum or in the oral cavity) may indicate a phase of hypothermia.

• Observation of the state of consciousness. Extreme fatigue, severe drowsiness, increasing confusion, decreased and uncoordinated muscle activity indicate hypothermia.

• Electrocardiogram. Shows abnormal heart rhythms.

• Blood gas analysis. The oxygen content and the pH value (ionic balance) indicate the current metabolic status of the organism.

First aid

If a person has symptoms of hypothermia, especially confusion, problems with thinking, an ambulance should be called immediately. If the person is unconscious, check the airway. If necessary, give artificial respiration, the method is also recommended if the victim takes less than 6 breaths per minute.