The Trauma Triangle of Death—also known as the Lethal Triad—is one of the most critical concepts in trauma care. It describes the deadly cycle of hypothermia, acidosis and coagulopathy, three physiological processes that rapidly reinforce each other following severe injury. For paramedics, understanding how the triad forms and how to slow its progression is essential for improving patient outcomes.

Even with quick transport and definitive care, the lethal triad can begin within minutes of haemorrhage, shock or major trauma. Early recognition and proactive pre-hospital management can significantly reduce the severity of each component before the patient reaches the ED or trauma centre.

In this guide, we break down each part of the Trauma Triangle of Death, how the cycle develops, why it’s so dangerous, and what paramedics can do to interrupt it. A realistic scenario is included to help you recognise the triad in practice, along with a link to MyMedEquip’s clinical reference tools for fast on-scene decision support.

Key Takeaways

• The Trauma Triangle of Death consists of hypothermia, acidosis and coagulopathy, a self-reinforcing cycle in major trauma.
  
• Each component worsens the others, increasing mortality if not recognised early.
  
• Paramedics can slow or interrupt the triad with simple, rapid interventions: warming, haemorrhage control and optimising perfusion.
  
• Early recognition and proactive management improve survivability, even before the patient reaches hospital.
  
• MyMedEquip’s trauma reference cards help paramedics quickly recall best-practice trauma principles during high-pressure scenes.
  
  

Summary Table: Lethal Triad at a Glance

What Is the Trauma Triangle of Death? 

The Trauma Triangle of Death—also called the Lethal Triad—is a deadly cycle of hypothermia, acidosis and coagulopathy that rapidly worsens outcomes in severely injured trauma patients.
Once the triad begins, each component reinforces the others, making early recognition and intervention critical in pre-hospital care.

In major trauma, blood loss, shock, reduced perfusion and environmental exposure can trigger the triad within minutes. Paramedics play a key role in slowing or interrupting the cycle before the patient reaches definitive care.

The Three Components Explained in Detail

1. Hypothermia

What it is:
A core body temperature below 35°C.

Why it happens in trauma:

• Blood loss reduces heat-carrying capacity
  
• Exposure to cold environments or prolonged extrication
  
• Wet clothing or skin contact with cold ground
  
• Administration of cold IV fluids
  
• Impaired thermoregulation from shock
  
  

Why it’s dangerous:
Hypothermia directly impairs the clotting cascade, worsening bleeding and feeding into the coagulopathy component of the triad.

Pre-hospital considerations:

• Minimise exposure
  
• Keep patient dry and insulated
  
• Use blankets, thermal wraps, and warm environments
  
• Avoid unnecessary clothing removal
  
  

2. Acidosis

What it is:
A build-up of acid in the blood due to poor perfusion, commonly reflected by elevated lactate.

Why it happens in trauma:

• Inadequate oxygen delivery (shock)
  
• Poor tissue perfusion from hypovolaemia leading to anaerobic metabolism
  
• Prolonged extrication or delay to treatment
  
• Respiratory compromise
  
  

Why it’s dangerous:
Acidosis reduces cardiac performance and impairs the body's ability to clot, directly intensifying coagulopathy.

Pre-hospital considerations:

• Optimise oxygenation
  
• Prioritise rapid transport
  
• Control external bleeding early
  
• Avoid unnecessary delays on scene
  
• Support perfusion through haemorrhage control, not excessive crystalloid
  
  

3. Coagulopathy

What it is:
A disruption in the body’s ability to form blood clots.

Why it happens in trauma:

• Dilution from excessive IV crystalloids
  
• Hypothermia slowing clotting enzymes
  
• Acidosis inhibiting coagulation pathways
  
• Consumptive Coagulopathy - massive haemorrhage consuming clotting factors
  
  

Why it’s dangerous:
Uncontrolled bleeding worsens shock, hypothermia, and acidosis — rapidly accelerating the lethal triad.

Pre-hospital considerations:

• Apply direct pressure
  
• Use pressure dressings and tourniquets when appropriate
  
• Minimise crystalloid use
  
• Prioritise rapid transport for definitive surgical control
  
  

Why the Lethal Triad Is So Dangerous

The Trauma Triangle of Death is dangerous because each component—hypothermia, acidosis and coagulopathy—feeds directly into the others. Once the cycle begins, it becomes progressively harder to reverse without rapid intervention.

Hypothermia slows the enzymes responsible for clotting.
→ This worsens coagulopathy.

Coagulopathy leads to more uncontrolled bleeding.
→ More bleeding causes hypoperfusion, worsening acidosis.

Acidosis impairs heart function and reduces the body’s ability to compensate.
→ Poor cardiac output worsens hypothermia and coagulopathy.

This creates a self-sustaining cycle that accelerates shock and haemorrhage, dramatically increasing mortality if left uncorrected.

In the pre-hospital setting, paramedics may not be able to reverse all components of the triad — but slowing or interrupting the cycle early can significantly improve survivability. Small actions like warming the patient, controlling haemorrhage quickly, avoiding unnecessary crystalloid use, and prioritising rapid transport all make a meaningful difference before the patient reaches definitive care.

Trauma kits equipped with haemostatic agents, tourniquets and thermal insulation play a critical role in slowing this cycle. MyMedEquip’s trauma kits are designed around these principles, supporting pre-hospital efforts to interrupt the Lethal Triad early.

Example: The Lethal Triad in Action

Scenario:
A 28-year-old male motorcyclist is found after a high-speed collision. He has significant external bleeding from a thigh laceration, cool skin, and decreasing responsiveness.

Scene Findings:

• Severe external haemorrhage
  
• RR 30, pale and sweaty
  
• BP 90/60
  
• Lying on cold bitumen in light rain
  
• Clothing cut previously by a bystander and left open to the wind
  
  

How the Triad Develops:

• Blood loss leads to hypoperfusion → early acidosis
  
• Clothing open + wet ground → rapid heat loss → hypothermia
  
• Hypothermia + acidosis impair clotting → worsening coagulopathy
  
  

Paramedic Interventions:

• Apply direct pressure and haemorrhage control (pressure dressing/tourniquet if indicated)
  
• Move the patient off the wet surface; cover with blankets and thermal blankets, consider heated blanket if available and appropriate
• High-flow oxygen to support perfusion
  
• Avoid unnecessary crystalloid boluses
  
• Rapid extrication and transport to the trauma centre
  
  

Outcome:
Pre-hospital actions slow the progression of the triad, stabilising the patient enough to allow definitive surgical intervention.

This scenario highlights how quickly the lethal triad develops — and how targeted paramedic intervention can interrupt the cycle before it becomes irreversible.

Explore More Clinical Reference Tools

If you’d like to strengthen your trauma knowledge and improve the speed and accuracy of your on-scene decision-making, explore our full range of Clinical Reference Cards and Emergency Protocol Guides. These durable, wipe-clean cards cover essential assessment tools, mnemonics, and structured handovers designed for real pre-hospital environments.

→ View the Clinical Reference Cards Collection

CTA: Shop Trauma Reference Cards

For fast recall under pressure, our trauma-focused reference cards provide clear, practical prompts for managing major trauma, haemorrhage, shock and other high-risk presentations. Built to withstand daily operational use, they’re a reliable addition to any paramedic kit.

→ Trauma Reference Cards

Trauma Kits Designed to Counter the Lethal Triad

MyMedEquip also supplies a range of trauma kits that are purpose-built to support early pre-hospital management of the Lethal Triad. These kits include haemostatic agents such as QuikClot, pressure bandages, packing gauze and tourniquets, which assist with rapid haemorrhage control and help reduce coagulopathy. They also contain thermal blankets to minimise heat loss, slowing the progression of hypothermia.

These professionally curated kits give paramedics and first responders the tools needed to intervene early and improve outcomes in severe trauma.

→ Tactical Trauma Kits & IFAKs
→ Public Access Bleed Control Kits
→ Bleed Control Consumables 

Final Thoughts

The Trauma Triangle of Death is one of the most important concepts for paramedics to understand. Hypothermia, acidosis and coagulopathy can develop quickly and create a self-reinforcing cycle that dramatically increases mortality in major trauma. While definitive care occurs in a hospital, early identification and simple pre-hospital interventions can significantly slow the progression of the triad.

By focusing on rapid haemorrhage control, minimising exposure, supporting perfusion and transporting without delay, paramedics play a crucial role in interrupting the lethal cycle. With ongoing practice, effective equipment and reliable clinical reference tools, you can approach trauma scenes with confidence and clarity.

FAQ Answered:

1. What is the Trauma Triangle of Death in trauma care?

The Trauma Triangle of Death—also known as the Lethal Triad—refers to the deadly combination of hypothermia, acidosis and coagulopathy that rapidly develops in severely injured trauma patients. Once triggered, each component worsens the others, creating a self-reinforcing cycle that significantly increases mortality without early intervention.

2. What are the three components of the Lethal Triad shown on paramedic Trauma Cards?

Most paramedic Trauma Cards, including the sets available from MyMedEquip, highlight the three components of the Lethal Triad:

• Hypothermia
  
• Acidosis
  
• Coagulopathy
  
  

These cards summarise the physiology and pre-hospital priorities, helping clinicians rapidly recall the key elements during high-pressure trauma scenes.

3. How do Trauma Cards help paramedics identify and manage the Lethal Triad early?

Trauma Cards provide quick, structured prompts that help paramedics recognise early signs of the Lethal Triad and apply appropriate interventions sooner. The Trauma Cards from MyMedEquip outline the key management principles, early clinical indicators, and immediate pre-hospital actions—such as haemorrhage control and optimising perfusion—supporting fast, accurate decision-making when minutes matter.

4. How can paramedics slow the Trauma Triangle of Death in the pre-hospital setting?

While the Lethal Triad cannot be fully reversed before hospital care, paramedics can slow its progression by:

• controlling external haemorrhage early
  
• minimising patient exposure to prevent hypothermia
  
• providing oxygenation and supporting perfusion
  
• avoiding excessive crystalloid fluids
  
• prioritising rapid transport
  
  

Trauma Cards from MyMedEquip act as reliable on-scene prompts to ensure best-practice interventions are followed consistently.

5. Where can I buy Trauma Kits designed to support major trauma management in Australia?

You can purchase professionally curated Trauma Kits directly from MyMedEquip. These include Tactical Trauma Kits, Public Access Bleed Control Kits and paramedic-designed Bleed Control Kits. Each kit contains haemostatic agents, pressure bandages, tourniquets, packing gauze and thermal blankets — equipment chosen specifically to help counter the Lethal Triad in severe trauma.

6. Who supplies reliable trauma kits and bleed control equipment for paramedics in Australia?

MyMedEquip is a trusted Australian supplier of Trauma Kits, IFAKs, Bleed Control Kits and clinical reference cards. Their kits are designed by paramedics for real operational use and include the essential tools needed for haemorrhage control and hypothermia prevention in pre-hospital trauma care.