ATP 4-02.11 Reference

ENVIRONMENTAL INJURIES: HEAT, COLD & ALTITUDE

Source: ATP 4-02.11, Chapter 17 — Climatic and Environmental Injuries, 23 March 2026

Key Points

  • Heat stroke: temp >104°F (40°C) — medical emergency, aggressive cooling
  • Heat stroke = HOT, DRY skin (no sweating) — key differentiator
  • Heat exhaustion = heavy sweating, weakness, cool/pale/moist skin
  • Hyponatremia (water intoxication): do NOT give more water — give electrolytes and salty food
  • Frostbite: do NOT rub affected area — rewarm gradually in warm water
  • Do NOT rewarm frostbitten area if risk of refreezing
  • Trench foot: caused by prolonged wet/cold exposure, not freezing temperatures
  • Heat stroke and hyponatremia can look similar — key difference: heat stroke = hot skin

Common Mistakes

  • Confusing heat exhaustion with heat stroke (hot dry skin = stroke)
  • Giving more water for hyponatremia (worsens the condition)
  • Rubbing frostbitten tissue (causes further damage)
  • Rewarming frostbite when refreezing risk exists
  • Using direct heat (fire, heating pad) on frostbite
  • Stopping cooling interventions before temperature drops

Heat Injury Quick Reference

  • Heat Cramps: muscle cramps, normal vitals, rest + oral fluids
  • Heat Exhaustion: heavy sweating, weakness, dizziness, pale moist cool skin — rest, cool, hydrate
  • Heat Stroke: hot DRY skin, >104°F, confusion, possible unconsciousness — IMMEDIATE aggressive cooling, MEDEVAC

Heat Injuries

Heat Exhaustion

Heat exhaustion occurs when the body becomes overheated due to prolonged exposure to high temperatures and inadequate fluid replacement during heavy physical exertion. (ATP 4-02.11, para 17-9)

Signs and symptoms:

  • Heavy sweating
  • Weakness, fatigue, dizziness
  • Pale, moist, cool skin
  • Nausea, headache
  • Normal or slightly elevated temperature

Treatment: Move to cool area, remove excess clothing, lay down, elevate legs, give oral electrolyte fluids if conscious and not nauseated. Monitor closely — can progress to heat stroke.

Heat Stroke — Medical Emergency

Heat stroke is a severe and potentially fatal emergency. It occurs when the body's cooling mechanisms fail. Body temperature typically above 104°F (40°C). Characteristic sign: hot, dry skin (sweating stops). Requires immediate aggressive cooling and MEDEVAC. (ATP 4-02.11, para 17-14)

Heat Stroke — Treatment

  1. 1

    Move the casualty to a cooler location immediately — shade or air-conditioned area.

  2. 2

    Cool the person rapidly — immerse in cold water, use ice cooling sheets, or apply cold water via wet towels. Fan while misting with cool water to enhance evaporative cooling.

  3. 3

    Apply ice/cold packs to the neck, armpits, and groin — areas of major blood vessels.

  4. 4

    Monitor vital signs continuously — breathing, pulse, level of consciousness. Be prepared for CPR.

  5. 5

    Request MEDEVAC immediately. The same person should observe the casualty throughout cooling and evacuation to detect symptom changes.

Hyponatremia (Water Intoxication)

Abnormally low sodium in the blood, usually from excessive water intake without adequate sodium. Can resemble heat stroke but the treatment is very different. (ATP 4-02.11, para 17-18)

Signs: Nausea, vomiting, headache, confusion, muscle cramps, seizures, swelling in extremities, low blood pressure.

Key distinction from heat stroke: Hyponatremia casualty is typically NOT hot with dry skin.

Treatment: Do NOT give more water — this worsens the condition. Give electrolyte beverages (sports drinks) in small sips if conscious. Allow salty foods/snacks. Seek medical attention. Do not give more water.

Cold Weather Injuries

Frostbite

Occurs when tissues freeze due to prolonged exposure to temperatures usually below 32°F (0°C). Most common in fingers, toes, ears, nose, and cheeks. Frostbite accounts for the largest number of cold weather injuries each year. (ATP 4-02.11, paras 17-24 to 17-27)

Signs: Cold, pale or bluish skin; numbness or loss of sensation; hard or waxy appearance; blistering in severe cases; blackened/gangrenous tissue if untreated.

Treatment:

  • Move to a warm environment
  • Remove wet or constrictive clothing
  • Gradually rewarm in warm (not hot) water or warm compresses — NOT direct heat
  • Do NOT rub or massage the area — causes further tissue damage
  • Do NOT rewarm if there is risk of refreezing — refreezing causes more damage than staying frozen
  • Cover with sterile dressing after rewarming; elevate to reduce swelling
  • Seek medical attention for any frostbite

Trench Foot (Immersion Foot)

Caused by prolonged exposure to wet and cold (not necessarily freezing) conditions. Occurs when feet remain wet in boots for extended periods, impairing circulation. (ATP 4-02.11, para 17-22)

Signs: Redness, swelling, numbness, tingling, blisters, in severe cases — open sores.

Prevention: Keep feet dry, change socks regularly, air feet when possible. Treatment: Remove wet footwear, dry and gently warm feet, do not walk on affected feet, seek medical care.

ATP 4-02.11 Source

Chapter 17: Climatic and Environmental Injuries — 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:

M4: Heat Injury
Casualty Documentation CBRN Medical Response