Cold Weather Survival (Notes)

RADIATION I R waves radiate from body due to temp. gradient. [Heat flows hot to cold] Key factors: Surface Area + Gradient

Direct contact between objects. Key Factor: Density [Water conducts 25x faster than air] Ground Steel CONDUCTION

CONVECTION Conduction to a moving substance molecules heat up and move away. New cold molecules move in. Key Factors: Density [Water vs. air] speed of movement. [Ex. Wind chill.]

EVAPORATION Perspiration/Respiration air heated and moisturized to breath. Insensible Perspiration: Sweat to keep humidity at 70% next to skin. Key Factor: Liquid decreases, Increases Susceptible to hypothermia.

~ Insulation [Layering and type] RESPONSE TO COLD Heat Retention ~ Size Shape ~ Insulation [Layering and type] ~ Fat ~ Shell/Core of body Cold Challenges ~ Temperature ~ Wetness ~ Wind ~ Density [H20] Heat Production ~ Exercise – Fitness – Fuel Stores – Fluid – Food ~ Shivering

How Your Body Regulates Core Temperature Vasodilation - increases surface blood flow, increases heat loss=cooling 2. Vasoconstriction - decreases blood flow to periphery, decreases heat loss.

How Your Body Regulates Core Temperature (Continued…) 3. Sweating = cooling 4.Shivering - generates heat through increase in chemical reactions required for muscle activity. Visible shivering can maximally increase surface heat production by 500%. However, this is limited to a few hours because of depletion of muscle glucose and the onset of fatigue.

How Your Body Regulates Core Temperature (Continued…) 5. Increasing/Decreasing Activity will cause corresponding increases in heat production and decreases in heat production. 6. Behavioral Responses - putting on or taking off layers of clothing will result in heat regulation

CORE BODY TEMP 98.6 degrees F ~ Above 105 deg. F enzymes denature. ~ Below 98.6 deg. F chemical Rxn slow. ~ Core= Internal organs esp. Heart, lungs, and brain. ~ Periphery= Appendages, skin, and muscle. * Core is essential to overall metabolic rate. CORE BODY TEMP

Metabolism increases = Heat generated increases Metabolism increases = Heat generated increases. Exercise increases metabolism to get energy to move muscles. Cold core temp slows chem. Rxns. Of metabolism. Impairs body’s ability to generate heat.

Brain directs metabolism. Heart/Lungs deliver 02 for met. and brain. H20 + Sugar + 02  Co2 + Energy Brain directs metabolism. Heart/Lungs deliver 02 for met. and brain.

Hypothermia Decrease in core temp. that impairs normal muscle and brain function. Hypo.= Decrease in core body temp. that causes problems w/muscle and brain function.

Conditions Leading To Hypothermia Cold Wind Wet fatigue food intake dehydration alcohol

STAGES OF HYPOTHERMIA STAGE CORE TEMP SIGNS MILD 95-99 FEEL COLD, GOOSE BUMPS, SHIVERING, HANDS NUMB, DEXTERITY LOSS MODERATE 95-93 90-93 INTENSE SHIVERING, LOSE COORDINATION, SLURRED SPEECH, DAZED, STUMBLES SEVERE 90-86 86-82 STOPS SHIVERING,SKIN BLUE,CANT WALK,CONFUSED, NO PULSE IN WRIST, MUSCLE RIGIDITY, SEMI-CONCIOUS, LOW PULSE & RESP. RATE DEATH SLOW, ERATIC BREATHING, CARDIAC FAILURE

At 90 degrees F, body starts to shut down all peripheral blood flow and decreases breathing and heart rate.

Hypothermia Assessment ~ Can stop shivering = Mild ~ Can’t count 100 – 1 by 9s = Moderate ~ Fails drunk tests = Moderate ~ No radial pulse = Severe ~ Stop shivering = Severe ~ Curled in fetal ball, pull out arm if it curls back up = Alive

Treatment Reduce Heat Loss ~ Clothing ~ Dry ~ Shelter 2. Food and H20 ~ Carbos = Fast -->

Protein = Increase in heat/g Fat = More cal/g *Warm liquids *No alcohol, caffeine, tobacco. External Heat Source Neck, armpits, and groin.

Vasoconstriction Hand/foot at 59 degrees F. Max. Construction At 50 degrees F periods of blood flow to increase heat in hand, 5-10 min. cycle. Acclimatization = Strong response with short interval.

Cause: Freezing of all skin layers muscle and/or bone. Frost Bite Symptoms: White wooden skin. All layers of skin hard Numbness Cause: Freezing of all skin layers muscle and/or bone.

Tissue Freezing Ice crystals form in cells. Fluid flows into cells. Cells break due to tearing by crystals or “pop” when too much H20 enters. **Do not rub frozen tissue** (Increase breakage by crystals.) 

Cell death  Tissue death. Tissue freezes at 28 degrees F. Areas with high surface area to volume ratios most susceptible ears, nose, fingers, and toes.

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Treatment Re-warm in 105-110 degrees F water. Circulate water and maintain temp by adding H20. Wrap in sterile gauze. Don’t use re-warmed part. **Do not let refreeze!!**

Cause: Frozen top layers of skin. Frost Nip Symptoms: White Waxy skin. Top layer hard and rubbery. Deeper tissue still soft. Numbness Blisters may occur = Popped cells. Cause: Frozen top layers of skin.

Re-warm with warm air or place against warm body part. Treatment Re-warm with warm air or place against warm body part. Do not rub!

Frozen Cornea Rapid re-warming w/compress or warm hand over closed eye. Patch for 24-48 hours.

Eyelashes Frozen Together Warm with hand. Snow Blindness Sunburn of eye. 8-12 hrs. later eyes dry irritated light hurts, swelling eyelids.

C. O. L. D. Keep it Clean Avoid Overheating Wear it Loose and in Layers Keep it Dry

Dressing For Cold Layers 1st Layer 2nd Layer 3rd Layer Must move moisture away – underwear. Insulating layer. Moves moisture out, traps warm in Completes moisture transfer. Wicking Warming or Insulation Weather