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Understanding Hypothermia: A Simple Approach

Understanding Hypothermia: A Simple Approach

Understanding Hypothermia: A Simple Approach

Hypothermia, a condition where the body’s core temperature dips below 35°C, poses a significant threat in various pre-hospital healthcare settings for first-responders. From frigid environments to austere settings where thermoregulation can be impaired, first responders and medical professionals must be capable of identifying, preventing, and managing hypothermic patients effectively.

Hypothermia Classifications: Primary vs. Secondary

Hypothermia can be categorized into two key types and it’s important that first-responders have a good baseline understand of the different classifications:


Primary Hypothermia: This is the classic case where a healthy person’s core temperature dips due to environmental factors. Examples include prolonged exposure to cold weather, windy conditions, or immersion in cold water. The body loses heat faster than it can generate it, thus leading to a drop in core temperature.


Secondary Hypothermia: This type arises when an underlying medical condition disrupts the body’s ability to regulate temperature. Common culprits include:

  • Reduced Heat Production: Conditions like sepsis, hypoglycaemia, or certain medications can impair the body’s internal heat-generating mechanisms.
  • Impaired Thermoregulation: Traumatic injuries (Blood loss) or myocardial infarction (heart attack) can disrupt the body’s thermostat, making it difficult to maintain a normal temperature

Pinpointing the exact number of hypothermic cases is challenging. In the United Kingdom, hospital admissions are likely to only capture the most severe instances. Generally speaking, poor urban areas see a higher prevalence of both primary and secondary hypothermia, often linked to environmental exposures, trauma, alcohol, drug use and homelessness. 

Sounds Chilly: But How?

Deep inside your brain sits a tiny control centre called the hypothalamus. It’s like your body’s own “Google Home Device,” working constantly to keep things running smoothly. Your hypothalamus receives messages from millions of nerve cells from your brain and body and reacts to them to keep your body in a stable state (something called homeostasis). One thing the hypothalamus helps manage is your body’s temperature.

Our bodies are just like intricate little moving ‘HIVE’ thermostats, maintaining a constant internal temperature through a mixture of heat production and heat loss. When exposed to primary and/or secondary factors heat loss outpaces production, triggering a series of physiological responses.

  • Shivering: The body’s initial defense mechanism, involving involuntary muscle contractions to generate heat.
  • Vasoconstriction: Blood vessels in the extremities constrict, diverting blood flow towards the core to protect vital organs. This explains the characteristic pale and cold skin in early hypothermia.
  • Metabolic adaptations: The body ramps up metabolic processes to generate heat, often leading to increased hunger and thirst.

Beyond the Shivers: The Signs and Symptoms

Hypothermia’s presentation can be difficult to identify for both first-responders and seasoned healthcare practitioners, particularly in its early stages. A high index of suspicion and awareness of risk factors are crucial for its early recognition. Here are key signs and symptoms to be vigilant for:

  • Shivering: As mentioned earlier, this is the body’s initial attempt to generate heat. However, in severe hypothermia, shivering may cease due to muscle fatigue.
  • Altered mental status: Confusion, slurred speech, and impaired judgment are common, making communication challenging.
  • Slowed vital signs: Decreased heart rate, respiratory rate, and blood pressure occur as the body attempts to conserve energy.
  • Fumbling: Loss of fine motor skills can manifest as difficulty with tasks like buttoning clothing, handwriting or holding a cup.
  • Paradoxical undressing: In rare cases, confused individuals may paradoxically remove clothing, mistaking the sensation of cold for feeling hot.
  • Severe cases: In advanced stages, muscle stiffness, seizures, and ultimately, coma can occur.

Cold: But How Cold?

There are 4 ‘grades’ of hypothermia; Mild, Moderate, Severe and Profound. In the pre-hospital environment, without an appropriate low-reading thermometer, it is often better to determine hypothermia and the severity using simple clinical signs and symptoms: 

Mild Hypothermia (32 – 35°C):

  • Tachycardia: A fast heart (pulse) rate, normally 100 beats per minute or more.
  • Tachypnoea: An increased breathing rate, typically 20 breaths per minute or more.
  • Vigorous Shivering: Uncontrollable shivering (We’ve all been there!)

Moderate Hypothermia (28 – 32°C):

  • Confusion: Impaired judgment, acutely confused.
  • Difficulty Speaking: Difficulty in speech due to fatigue of the muscles. 
  • Reduced Shivering: Reduced ability to globally shiver.
  • Cyanosis: A blue, purple like tinge to the colouration of the skin. Particularly around the mouth and nose.

Severe Hypothermia (24 – 28°C):

  • Reduced Response: Progressive decreased level of consciousness.
  • Absent Shivering: Loss of reflexes and voluntary movement.
  • Drop in Vital Signs: Pulse rate and oxygen consumption decreased, leading to a slow heart rate and breathing rate.

Profound Hypothermia (<24°C):

  • Unresponsive: Absent level of consciousness (Will appear dead).
  • Absent Movement: No reflexes or response to stimuli.
  • Absent Vital Signs: No signs of life, including cardiac and respiratory activity.

Get Warm: Preventive Measures.

Prevention is the cornerstone of managing hypothermia. Here are key strategies first-responders and healthcare professionals can implement:

Environmental control: Maintain a warm ambient temperature in treatment areas and ensure patients wear appropriate clothing for the expected conditions. Wet clothing should be removed promptly and replaced with dry, insulating layers.

Hydration: Dehydration can further exacerbate hypothermia so it’s important to remain hydrated. Currently there’s poor evidence to support the benefits of warm drinks in hypothermic patients. (Although, it might definitely make you better!).

Monitoring: Regularly monitor core temperature and vital-signs. Early detection allows for timely intervention.

Addressing underlying conditions: Promptly treat any underlying medical conditions that may contribute to hypothermia. Such as blood loss in trauma (and medical) patients.

Too Late – Too Cold: What Next?

When hypothermia is suspected, immediate action is paramount. We have something called ‘SHIVER’ – A mnemonic to aid first-responders on a step-wise methodical approach to managing patients with hypothermia.

S: Stop further heat loss:
Remove and replace any wet clothing and make sure their head is covered. If the casualty is outside, try to get them indoors. If there are no buildings available, try your best to shelter them from the elements such as the wind and rain.

H: Handle (Move) with care:
Moving hypothermic patients with a core body temperature of between 30-24°C can cause sudden cardiac arrest, especially if the patient is severely hypothermic and has risk factors for imminent cardiac arrest.

I: Insulate from the ground:
Lay the Patient on a ground layer or dry, insulating material such as pine branches. Cover the patient with dry layers, or warm them in a sleeping bag or a hypothermia survival blanket. Putting blankets on top of hypothermic patients won’t help if they’re cold at the bottom.

V: Vital Signs:
Regularly monitor the patient’s breathing rate, level of response, and temperature. In the most severe cases of hypothermia, vital signs such as breathing rate and pulse rate can be extremely difficult to assess. It’s recommended that pulse rate and breathing rate should be calculated over a 60 second period for more accuracy.

E: Ensure Helps Is Alerted:
It goes without saying that hypothermic patients in a pre-hospital setting probably need interventions at hospital. Call 999 or 112 for emergency help early. 112 will work across Europe; outside of Europe, use the local emergency numbers. Try not to leave the patient alone if possible unless you are in a remote area and cannot call for emergency help.

R: Rewarm slowly:
Do not place any direct heat such as hot water bottles on the patient as they may cause burns. Furthermore, do not place the patient directly in front of any heat sources such as heaters and fires. Hypothermic patients should be warmed gradually.

Hello, can you hear me? No response:

If there’s no signs of life, then the patient is in cardiac arrest. Evidence suggests that early intervention for hypothermic arrests can have a relatively positive outcome. Here’s some important factors to remember when it comes to hypothermic resuscitation:

  • Hypothermia may cause chest wall stiffness with ventilations and compressions also being more difficult to achieve.
  • ALS (Advanced Life Support) drugs are less likely to be effective at low body temperatures: (One for Healthcare Professionals) do not give ALS drugs if the core temperature is below 30°C.
  • Defibrillation is less likely to be effective at low body temps: if VF persists after 3 shocks, delay further defibrillation until the core temperature is above 30°C.
  • Hypothermia is protective and good outcomes have resulted from prolonged resuscitation of hypothermic patients. There are a few cases of hypothermic cardiac arrest patients recovering after very long resuscitation attempts. (4-6 hours in some cases).  

What Are You Packing: Kit Essentials:

By understanding the mechanisms of hypothermia, recognizing its subtle and sometimes deceptive presentation, and implementing effective preventive and treatment strategies, first-responders can play a vital role in safeguarding patients from this potentially life-threatening condition. So what equipment should you carry for managing hypothermia?

Here are some recommendations: 

Blizzard Compact Trauma Blanket: made from ultra-light 2-layer reflexcell™ the blizzard 2 layer compact trauma blanket is lightweight, compact and ideal for carrying in your rucksack, in the car or on the go. The blizzard 2 layer compact trauma blanket has unrivalled thermal qualities and is an effective tool for the prevention and treatment of hypothermia provided warmth of up to 5 tog.

Blizzard EMS Trauma Blanket:  The blizzard ems trauma blanket is a full length, lightweight, 2-layer blanket. It uses the unique reflexcell technology to protect patients from hypothermia.

Blizzard Beanie Hat: The blizzard beanie hat is a high performing insulating hat (tog 7.5), which is windproof and waterproof. It can be used alone or under other headwear for extra insulation.

REAL.MEAL bars: Real.Meal bars are the world’s most comprehensive and nutritionally-complete meal replacement bar offering over 600 calories per 150g bar. Cold patients use up significant amounts of energy. These bars replace it. Plus, they taste amazing.

Hypothermia Control Kit: Save time hunting around, check out our world’s first all-in-one hypothermia control kit for pre-hospital care. Respond quickly, effectively manage hypothermia with our innovative hypothermia control kit. A pre-packed solution containing everything you need to prevent and manage hypothermia.

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