COLD INJURY

Types of Cold Injury• Nonfreezing (see back up slides for details)

– Chilblains– Trench foot

• Freezing– Frostbite

• Hypothermia• Cold injury occurs on a spectrum

Frostbite• Injury resulting from freezing and ice crystal formation in skin/underlying tissues• Superficial, injury contained within skin layers:

– Skin is red, progressing to pale-white and firm to the touch– Cold sensation, tingling, itching, burning or numbness– Superficial blisters with clear/milky fluid, surrounded by redness and swelling

can develop post rewarming• Deep, may extend to muscles/bone:

– Skin is white-yellow and waxy in appearance & hard to the touch – Decreased sensation, affected body part feels clumsy or absent – Swelling, deep blisters contain bloody fluid and skin turning purplish-blue will

develop post rewarming • Patients with frostbite will experience severe pain on rewarming

Frostbite Decision Making• If within 2 hours of definitive medical care, evacuate and delay rewarming

– Injury may thaw spontaneously – do not deliberately keep frozen• If more than 2 hours from a hospital, rewarm if refreezing can be prevented

– Thawed tissue that refreezes almost always dies!

Passive Frostbite Rewarming• Active, rapid rewarming w/warm water immersion is the preferred method

– See back up slides for details• If active rewarming is not possible and thawing is required

– Move patient to warm shelter such as a tent or cabin– Warm affected tissues with skin to skin body heat such as placing hand into

armpit or foot against caregiver’s abdomen

First Aid for Frostbite• Remove wet, constrictive clothing and jewelry• Handle frostbitten tissue gently and protect it from injury• Do not allow use of frozen or thawed tissue unless mandatory for individual or

group safety• Apply clean, dry padding between fingers/toes/around frozen tissue• If available, apply topical aloe vera to thawed tissue before applying dressings• Use ibuprofen for pain control• Elevate thawed extremities to reduce subsequent swelling

Cautions for Frostbite• Do not rub the frozen part or apply ice or snow• Do not attempt to keep tissue frozen to prevent spontaneous thawing• Do not attempt to thaw in cold water• Do not attempt to thaw w/direct heat sources such as stoves/fires• Do not allow patient to use alcohol/tobacco• Do not break blisters in the field• Never attempt rewarming if refreezing is likely – it is better to walk out on

frozen feet than to have them refreeze– But do not allow walking on frostbitten feet unless required for individual or

group safety• Previous frostbite injury usually results in increased sensitivity to cold, requiring

additional care in maintain warmth and minimize cold exposure

Prevention of Frostbite• Maintain good physical fitness• Dress in layered clothing and properly fitting shoes; cover all exposed skin• Wear mittens instead of gloves in severe cold• Keep feet and hands dry• Consider use of small chemical heat packs• Maintain proper hydration and nutrition• Avoid alcohol and tobacco• Terminate exposure/seek shelter if weather worsens• Check your teammates face’s for signs of frostbite (white patches)• Repeatable inquire on the status of your teammates feet and hands

Hypothermia• Decrease in the body’s core temperature below 95⁰F (35⁰C)

Body Temperature Regulation • Conduction: heat is transferred to cooler objects

– Limit direct body contact with cold objects; use insulation• Convection: body heats air around it

– Warm air is moved away by wind– Maintain barrier against wind and get out of elements

• Radiation: body gives and receives heat– Dark clothes accept more heat from sunlight

• Evaporation: sweating results in heat loss– Layer clothes to prevent overheating and sweating

Basic Treatment for all Stages of Hypothermia• Prevent further heat loss

– Insulate person from the ground– Protect from the wind– Replace wet clothes with dry ones– Cover person with vapor barrier such as tarp– Move person to warm environment

Stages of Hypothermia• Mild: Patient alert and shivering• Moderate: Patient drowsy, not shivering• Severe: Patient unconscious• Profound: Patient not breathing

Critical Distinction!Alert & Shivering = Mild

Not shivering = Moderate or Worse

Mild Hypothermia Treatment• Mild hypothermia, patient is alert & shivering• Shivering is a very effective method of generating body heat• Patients can be rewarmed with dry insulation as long as they are shivering• Light exercise is helpful for mild hypothermia• If alert and able to drink, provide fluids containing sugars to fuel shivering

Moderate to Severe Hypothermia Treatment• Moderate: Patient drowsy, not shivering• Severe: Patient unconscious• Treat patient very gently, vigorous stimulation or changes in position (supine

to sitting/standing) may cause cardiac arrest • Do not attempt to increase heat production through exercise• Do not allow patient to drink fluids unless able to hold container• The non-shivering hypothermia patient needs external heat to rewarm• Small chemical hot packs & skin-to-skin contact with a warm body in sleeping

bag are generally insufficient for rewarming hypothermia patients, but can be helpful to prevent additional heat loss

• Larger heat sources such as hydration bladder filled w/hot water, wrapped w/cloth to prevent burns, can be useful when placed with person in sleeping bag

Constructing a Hypothermia Wrap1. Place tarp on ground to act as vapor barrier2. Place sleeping pad on tarp as insulation from ground

3. Place sleeping bag atop sleeping pad4. Place patient into sleeping bag5. Fold corner of tarp across feet

6. Fold one side of the tarp around the patient

7. Fold other side of the tarp around the patient

Prevention of Hypothermia• Wear proper clothing to keep warm and dry• Layer clothing to prevent overheating and sweating• Stay out of the wind • Terminate exposure: keep warm and dry, seek shelter• Hydrate properly and maintain nutrition• Avoid alcohol and drugs in wilderness

Groups at Risk for Cold Injury• Infants: do not conserve heat as well as adults• Elderly: lower metabolism produces less heat• Physically unfit or ill: decreased energy stores• Alcohol: dilates blood vessels, which increases heat loss; causes poor judgment• Trauma: decreased physical activity, laying on cold ground, blood loss• Persons improperly dressed, dehydrated or lacking proper food

Dressing for the Cold • No cotton clothing; choose wool or synthetics that wick moisture, dry quickly

and maintain insulating properties when wet• Layer clothes, add layers for increased warmth, remove layers to avoid

sweating• Wear breathable water/wind resistant shell as outer layer• Ensure proper fit of shoes • Wear hat and gloves/mittens; cover all exposed skin using face mask / scarf /

gaiter / goggles

Other Preventive Principles• Appoint group leader or use buddy system to ensure individual safety and

welfare– Check each others faces for signs of frostbite (white patches)– Repeatable inquire on the status of your “buddies” feet and hands

• Avoid the outdoors during extreme weather and terminate exposure/seek shelter if unable to stay warm

• Carry first aid kit, food, water, extra clothes, and means for shelter & fire starting

• Leave trip plan with someone and develop procedures for if/when you become overdue

• Carry means of communication, such as a cell phone or emergency beacon – Keep these devices warm (inside your jacket) and powered down when not

in use

Winter Clothing & Pack Considerations• Pack, 40 – 50 liters / 2,500 – 3,100 cubic inches • Boots, insulated & water proof • GaitersNO COTTON, all items wool or synthetic • Wool socks (I’ve not found a good synthetic option) • Extra socks (optional)• Light / medium weight base layers, top/bottoms – wool is my 1st choice• Extra top base layer (optional - prone to sweating?) • A) Insulated pants - soft shell / Fleece / wool (optional)• B) Hard shell pants - breathable wind/water proof, preferably w/full side zips (optional)

– Use A or B, or A + B • Insulating top layer: Soft shell / Fleece / wool - jacket / sweater • Insulating top layer: Soft shell / Fleece / wool – vest / sweater (optional)• Hard shell jacket w/hood: breathable wind/water proof, preferably w/pit zips• Insulated jacket: down / synthetic / wool – preferably large enough to fit over shell & existing layers

– Down is great IF your confident you can keep it dry!! Best insulator / weight– Synthetic, Primaloft is my 1st choice– Wool, heavy

• 2 Hats: fleece / wool – 1 light weight & 1 heavy weight• Balaclava / face mask / scarf / gaiter: fleece / wool (optional)• Goggles (optional) • 2 pair of gloves: synthetic / wool / fleece with shell• Mittens: synthetic / wool / fleece with shell (optional)

• Snowshoes / skis / micro-spikes • Ski poles (optional)• Food & water for 24 hrs:

– high calorie foods that are not impacted by freezing (trail mix, granola bars, etc.)– thermos w/hot non-caffeinated & sweetened beverage (tea & honey, jell-o, Gatorade, etc…) – Insulated water bottle container

• Map / compass / GPS + extra batteries, Lithium batteries for temps below zero• Whistle• 2 headlamps + extra batteries (extra bulbs if not LCD), Lithium batteries for temps below zero• First aid kit: personal • Trail tape / flagging• Pencil / pen & notebook / paper• Matches / lighter • Fire starting material• Knife • Small folding saw (optional)• Space blanket / light weight tarp / bivy bag• heavy duty trash bag, 1-2• Chemical hot packs: 4-6 • Light weight cord, 20-40 feet • Chemical Light sticks (optional)• Light weight sleeping bag (optional)• Ensolite pad (optional), best if a removable component of your packs suspension system

Winter Clothing & Pack Considerations – continued

Always seek professional medical evaluation and treatment for

hypothermia and other cold injuries!

Questions?

Back up slides follow

• Active Frostbite Rewarming:– Immersion for about 30 minutes in a circulating warm water

bath (104-108⁰F) is ideal if the thawed tissue can be kept in a warm environment afterwards

– Ensure that the water is not too hot before inserting affected tissue – DO NOT allow burns

– Do not towel dry; let tissue dry in warm air– Thawing may cause severe pain, requiring narcotics to control

Nonfreezing Cold Induced Injuries - Chilblains• Localized, inflammatory, bluish red lesions• Develop within several hours of usually brief exposure to cold• Intense itching, burning, or pain; aggravated by heat• Normally resolve within days to three weeks

• Prevention– Minimize any cold exposure if prior history of chilblains

• First Aid– Dry and gently massage affected skin– DO NOT expose to direct heat or hot water to rewarm– Ibuprofen for pain control

Nonfreezing Cold Induced Injuries – Trench Foot• Prolonged exposure to cold, wet

conditions (32 – 59⁰F)• Pale, cold tissue, and numbness• Followed by redness, swelling, and pain

after rewarming• Pain aggravated by heat and dependent

position

• Prevention– Maintain body core temperature and

blood flow to feet by remaining active– Change socks frequently and keep feet dry– Wear proper sized shoes; do not lace

tightly • First Aid

– Rewarm body core, but not affected extremities

– Elevation and ibuprofen for pain control– DO NOT rub affected tissue