ATP 4-02.11 Reference

HYPOTHERMIA PREVENTION & MANAGEMENT

Source: ATP 4-02.11, Chapter 8 — Hypothermia Control, 23 March 2026

Key Points

  • Hypothermia is the "H" in MARCH-PAWS
  • Hypothermia begins when core temp drops below 97°F
  • Mild: 93–96°F | Moderate: 89–93°F | Severe: <89°F
  • The Lethal Triad: hypothermia + acidosis + coagulopathy
  • Massive bleeding can cause hypothermia — cold prevents clotting = more bleeding
  • Diagnose core temp rectally with low-range thermometer only
  • Prevent hypothermia even in warm weather for casualties in shock
  • Remove wet clothing; use HPMK or any available insulation

Common Mistakes

  • Ignoring hypothermia risk in warm/mild weather for bleeding casualties
  • Leaving wet clothing on casualty
  • Not insulating beneath the casualty (heat loss to ground is significant)
  • Applying direct heat sources (hot packs directly on skin can burn)

The Lethal Triad

Three conditions that compound each other and dramatically increase mortality:

  • Hypothermia — impairs clotting, leads to coagulopathy
  • Acidosis — low pH from poor perfusion, lactic acid buildup
  • Coagulopathy — inability to form blood clots, worsening hemorrhage

Each component worsens the others. Breaking the cycle early (especially hypothermia) is critical to survival.

Critical Principle

Massive bleeding can cause hypothermia, which in turn can cause more bleeding because cold temperatures prevent blood from clotting properly. This is a problem even in warm weather for casualties in shock who cannot generate enough body heat. It is crucial to stop this cycle to save the person's life. (ATP 4-02.11, para 8-5)

Hypothermia Stages

Stage Core Temperature Signs and Symptoms
Mild 93–96°F (34–36°C) Shivering, cold and pale skin, numbness or tingling in extremities, confusion beginning
Moderate 89–93°F (32–34°C) Shivering decreases or stops, worsening confusion, slurred speech, slow breathing and drowsiness, weak pulse, low blood pressure, poor body movement control
Severe <89°F (<32°C) No shivering, unconsciousness, very weak or absent pulse, very slow/absent respiration, pupils dilated, may appear dead

General Signs of Hypothermia

  • Vigorous shivering (typically present in early stages)
  • Shivering may decrease or cease as core temperature continues to fall
  • Conscious but usually apathetic or lethargic
  • Confusion, sleepiness, slurred speech or mumbling
  • Slow breathing and drowsiness
  • Weak pulse; low or unattainable blood pressure
  • Change in behavior with or without poor control over body movements and slow reactions

Field Hypothermia Prevention and Treatment

The primary field intervention is preventing further heat loss. Active rewarming is generally beyond the scope of field care, but aggressive insulation and removal of wet clothing are critical. (ATP 4-02.11, para 8-9)

  1. 1

    Move the casualty out of the elements — wind, rain, and cold ground accelerate heat loss. Get to cover if tactically feasible.

  2. 2

    Remove wet clothing — Wet clothing conducts heat away from the body up to 25 times faster than dry clothing. Cut away if needed; preserve tactical gear/weapons.

  3. 3

    Insulate from below — Place casualty on a litter, sleeping pad, poncho, or any insulating material off the ground. Significant heat is lost to the ground through conduction.

  4. 4

    Apply Hypothermia Prevention and Management Kit (HPMK) — if available. Wrap the casualty in the vapor barrier and reflective blanket. Cover the head.

  5. 5

    If HPMK unavailable: Use sleeping bags, ponchos, space blankets, extra BDUs, or any available material. Cover the head — significant heat is lost through the head.

  6. 6

    Document — Record hypothermia prevention measures taken on DD Form 1380. Alert receiving medical personnel of suspected hypothermia.

Warming Guidelines

  • For mild hypothermia: Remove wet clothing, insulate, and provide warm (not hot) beverages if conscious and able to swallow
  • For moderate/severe hypothermia: Insulate aggressively; do NOT rub extremities (can cause dangerous cardiac arrhythmias); handle gently; MEDEVAC priority
  • Apply chemical heat packs to armpits, groin, and sides of neck (NOT directly to skin); wrap in cloth first
  • Do NOT give alcohol — it dilates blood vessels and accelerates heat loss

ATP 4-02.11 Source

Chapter 8: Hypothermia Control — Army Techniques Publication 4-02.11, Casualty Response, Tactical Combat Casualty Care, and First Aid. Headquarters, Department of the Army, 23 March 2026.

See It in Practice — ESB Tasks

These ESB Medical Lane tasks apply this doctrine directly:

M6: Spinal Injury & Shock
Shock Recognition Secondary Injury Assessment