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21st June 2024

Hypothermia in trauma: Navigating the Lethal Triad

The Lethal Triad describes a combination of physiological conditions that can occur in trauma patients. Referred to as “the triad” due to the cycle that is created. Each condition exacerbates the others, making it extremely challenging to treat, but vital to address quickly.

This trio consists of hypothermia, acidosis, and coagulopathy. At THERMARMOUR, we are specifically familiar with the role of hypothermia in trauma patients and understand the importance of early intervention.

We explain everything you need to know about the lethal triad, from what it is, to management strategies.


The role of trauma

lethal triad

Understanding trauma and its effects is key in navigating the Lethal Triad. From the International Journal of Orthopaedic and Trauma Nursing:

“Musculoskeletal injury brings with it a pattern of physical trauma that can result in death in the hours, days, and months that follow. It is important that orthopaedic trauma practitioners have the knowledge and skills to provide care for the injured patient that takes into account the physiological impact of trauma so that they can deliver best evidence-based care for their patients.” [1]

As of 2020, trauma was one of the biggest causes of death and disability in the UK, with the most commonly sustained injuries being through road traffic accidents, crime, and falls. [2]

From this data, we can see a significant need to stay up to date with the latest knowledge and treatments regarding traumatic injuries, understanding the Lethal Triad being a part of this.


What conditions make up the Lethal Triad?

In trauma situations, there are a wide variety of conditions and complications that can occur in a patient, depending on the severity of the incident.

The “Lethal Triad” is one of these complications, and unfortunately, it can be life-threatening. Three conditions make up this triad, these are:



Hypothermia commonly occurs in trauma patients; it happens when the core temperature drops below 36C. This can be due to blood loss, haemorrhage, environment, injury, or shock. A traumatic injury can disrupt the body’s normal temperature mechanisms, making it harder to maintain normothermia. [4]

The impairment of metabolic functions and things such as blood loss can further increase the risk of hypothermia developing. Not only can the trauma increase this risk, but the environment plays a significant factor.

If an injury occurs in cold and extreme weather, without adequate access to shelter and warm clothing or coverings, the risk of developing hypothermia increases even further.



This condition arises when the body accumulates too much acid. One common cause of this is the impaired oxygen delivery to the tissues, combined with the inadequate removal of carbon dioxide from the body.

Complications such as acute blood loss, vasoconstriction in response to hypothermia, and overall decreased cardiac output can damage the oxygen delivery to the tissues. [3]. Resulting in the tissue oxygen demand exceeding the oxygen that the body is able to deliver in these circumstances.



This refers to the inability of the body to clot properly, which can be worsened by hypothermia and acidosis. Clotting is necessary to control bleeding. Without effective clotting, a trauma patient can experience a loss of blood volume, and further complications.

According to the Journal of Emergency Medical Services, “coagulopathy in trauma is a common occurrence, present in nearly one in four severely injured patients arriving at the ED.” [3]  Uncontrolled bleeding can quickly become life-threatening, and this can be further exacerbated by the other two components of the Lethal Triad.


How do these conditions affect one another?

The Lethal Triad increases the difficulty in treating trauma patients due to the cyclical nature of each condition, and the way they interact with one another. Let’s take a look at an example of this:

With a traumatic injury, there may be a haemorrhage or bleeding, which requires our clotting formation process to be working efficiently. However, with the involvement of hypothermia, this becomes difficult.

Lower core temperature delays clot formation, impairs platelet function, and can enhance fibrinolysis. This counteracts the efforts of the body to stabilize bleeding. In general, lower temperatures negatively affect the body’s metabolic processes.

The self-perpetuating cycle of the Lethal Triad may look something like:

Hypothermia induces Coagulopathy: The lower core temperature present in hypothermia patients impairs their clotting mechanisms, causing increased bleeding.

Bleeding worsens Hypothermia: Continued blood loss can reduce the body’s ability to maintain heat, dropping the core temperature even further. When already hypothermic, this presents a serious risk to the patient if treatment is not immediate.

Acidosis aggravates both conditions: Acidosis can worsen these conditions by impairing cellular metabolism.

As Acidosis can compromise the clotting process, more blood can be lost from the patient, which in turn, worsens hypothermia. Then, as hypothermia worsens, it continues to impact the body’s clotting mechanisms, and the cycle continues until treated appropriately. [5]


Management strategies

Each patient, and situation is unique, and their treatment should reflect this. One thing that can be agreed upon is that urgency in treatment, and an understanding of the complications of trauma are key to the patient’s outcome.

An article in the Journal of Emergency Medicine [3] highlights some ways for emergency service providers to tackle the Lethal Triad. Some of these include:

  1. The triad begins and ends with bleeding, so find the bleeding and stop it. Hold pressure, use combat gauze, apply a tourniquet, bind the pelvis, etc.
  2. Do not stop your search for bleeding with the first source you find, as others may exist.
  3. Always assume your patient’s temperature is dropping right before your eyes, because it is, and much faster than you’d expect.
  4. Patients can and will become hypothermic in conditions you consider warm. Prioritize limiting a patient’s exposure to the environment, especially during prolonged extrication.
  5. Turn up the heat in your ambulance. If you aren’t sweating, it’s certainly not warm enough. (Ideally, 27 degrees C.)
  6. Promptly remove wet or bloody clothes and replace with a warm blanket. Shivering wastes valuable cellular energy and oxygen in an attempt to stay warm while producing more lactate, contributing to acidosis.

You can read the full list of steps here.


Emergency hypothermia products

Hypothermia is a major contributor to morbidity and mortality within trauma patients or those stuck in cold conditions.

THERMARMOUR can help by alleviating this heat loss and allow the patient to begin to return to a normothermic state without introducing an active heat source. Emergency blankets and Emergency ponchos are recommended to be carried by first responders, paramedics and search & rescue teams.

They are simple to use, take up little storage space, and begin working from the moment they are applied to the patient. THERMARMOUR emergency products are standalone, meaning they require no additional heat sources to work. This makes them particularly efficient for emergency situations.

lethal triad
THERMARMOUR Emergency Blanket

Compressed packaging for ease of storage

Can be cut to size as needed

X-ray compatible and latex free

No heat source required

Standalone, patient specific

Soft fleece lining inside



THERMARMOUR Emergency Poncho

Shower proof with high visibility levels

Non-conductive and radiolucent

Compressed packaging for ease of storage

No heat source required

Can be cut to size as needed

Soft fleece lining inside


Get in touch

If you have any questions about our range of emergency products, you can contact us, or follow us on social media. Ordering THERMARMOUR products is easy, simply shop our products online and benefit from fast UK mainland delivery. For larger orders, get in touch our friendly team to discuss your specific requirements.






Categories: Emergency, Interesting info

Tags: hypothermia, injury, the lethal triad, trauma

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