Cold-Related Illness. Matthew Gammons, MD Killington Medical Clinic Vermont Orthopaedic Clinic

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1 Cold-Related Illness Matthew Gammons, MD Killington Medical Clinic Vermont Orthopaedic Clinic

2 Hypothermia Frost nip Frostbite Chillbains Trench foot Cold-Related Illness

3 Who gets it? How common? Outdoor events Skiing, snowboarding, mountaineering, open water swimming Any athlete participating in cool/cold temperatures is at risk High rates of hypothermia in open water swims Reported in up to 80% of participants

4 Heat loss Evaporation Convection Conduction Radiation Respiration

5 Heat Loss Evaporation Occurs when water is transformed into vapor Occurs with skin perspiration and respiratory tract Activity increases evaporative losses Radiation Direct emission of heat Largest source of heat loss Clothing does not affect significantly

6 Convection Heat Loss Transfer of body heat to cold air or water in contact with the body surface Increased by wind or motion of water and by increased temperature differences Windproof clothing and insulation can decrease loss Conduction Direct contact transfer of heat from the body to a colder surface Water and wet clothing are good conductors

7 Wind chill Wind combined with cold that causes a lower relative temperature Significantly increases heat loss Most significant in the first 20 m.p.h.

8 Thermoregulation Body is better at dissipation of heat than retention Body temperature needs to be maintained between 95 F ( 34 C) and 105 (40.5 ) Shunting of peripheral blood flow to the core is the first adaptation to cold Hypothalamus signals shivering and thermogenesis Increased thyroxine, epinephrine and norepinephrine Relatively ineffective

9 Cold causes Muscle Physiology Nerve conduction to slow Muscle contraction to slow Decreases tissue elasticity Decreases power output

10 Accidental Hypothermia Unintentional decline in core body temperature Mild C (90-95 F) Moderate C (82-90 F) Severe C (82-90 F)

11 Mild Hypothermia Signs and Symptoms Confusion Slurred speech Impaired judgment Amnesia Tachycardia Tachypnea Increased shivering Treatment Prevent further heat loss Blankets Remove wet clothing Encourage warm foods and liquids Passive rewarming is generally adequate

12 Moderate Hypothermia Signs and Symptoms Lethargy Hallucinations Progressive bradycardia Hypoventilation J waves- on ECG a deflection occurring between the QRS complex and the onset of the ST Decreased shivering Treatment Patient unable to warm themselves Prevent further heat loss Blankets Remove wet clothing Active external rewarming Active internal rewarming

13 Moderate/Severe Hypothermia Warning! These patients should be handled with caution as movement can induce ventricular fibrillation

14 Severe Hypothermia Signs and Symptoms Coma Loss of ocular reflex Decrease BP and output Ventribular fibrillation Asystole Patient appears dead Treatment Transport CPR if no pulse or breathing Hold for any pulse CPR may cause arrythymia Do not shock until warm Core temp above 30 C (86 F) Active external rewarming Active internal rewarming

15 Active External Rewarming Forced hot air Hot packs/water bottles Warming blankets Heat lamps Immersion of extremities in warm water Theoretical concern of shock from whole body immersion Body to body contact Relatively ineffective when compared to internal 1.5 C per hour Less risk of rewarming complications Aftershock (rewarming shock)

16 Active Internal Rewarming Warm humidified oxygen Raises core temp 1-2 C per hour Warm IV fluids Relatively ineffective but may help with relative hypotension Extracorporeal blood rewarming Gold standard 1-2 C every 3-5 min Most effective More invasive Risk of rewarming complications Aftershock (rewarming shock)

17 Rewarming shock No strong evidence Peripheral warmth decreases vasodilitation Blood flows to cooler extremity causing decrease rather than increase in core temp In combination with dehydration, cold diuresis may lead to hypotension and hypoperfusion

18 Freezing injuries Frostbite Cold injury caused by freezing of tissue Tissue ischemia Release of inflammatory mediators Results in healing or necrosis Commonly affects in hands, feet, nose ears. Mild forms relatively common in cold weather athletes

19 Frostbite Initial appearance is similar Firm, pale, cold, numb tissue Classification becomes apparent with rewarming Superficial ( 1 st and 2 nd degree) Only skin Generally heals without tissue loss Deep ( 3 rd and 4 th degree) Skin and subcutaneous tissue Associated with permanent tissue loss

20 Frostbite- rewarming/classification Superficial Hyperemia Increased sensation Throbbing Edema Clear blisters Deep Mild/Moderate Deep Hemorrhagic blisters Eschars post blister 1-2 weeks Severe Deep No blisters Minimal edema Skin purple to black Mummification and autoamputation occur 3-6 weeks

21 Frostbite Treatment Rewarm tissue only if it will remain warm Rapid rewarming in warm water C ( ) Until thawing is complete ( min) No rubbing as this may increase tissue damage Oral non-steroidal anti-inflammatories may limit tissue damage Some promote aspirin use for both pain and healing

22 Frostbite Treatment Use of antibiotics (severe) in frostbite is controversial and not likely necessary Vasodilators (iloprost,) viscosity decreasers (pentoxifylline) and intravascular thrombolysis have shown promise in decreasing tissue damage in severe cases Some recommend draining clear blisters other recommend leaving blisters intact Hemmorraghic blister should generally not be drained Early surgical debridement is not indicated

23 Non freezing injuries Frostnip Prefreezing tissue injury due to local vasoconstriction Skin appears white or pale Easily thawed followed by pain, redness, swelling Skin may peel later Generally full recovery but indicated inadequate protection Chillblains ( pernio ) cold sores Local tissue injury with erythema, cyanosis, nodules, plaques and ulcers Believed to be related to non-freezing vasconstriction in at risk individuals Generally recovery and treated similar to frostnip

24 Non freezing injuries Trench foot aka immersion foot Soft tissue, muscle, nerve and vessel injury Non-freezing injury caused by repetative vasoconstriction Prolong exposure Can occur in as little as 12 hours. More commonly 3-4 days Treatment Clean and dry extremity NSAIDS Protect from cold and wet May lead to permanent cold sensitivity

25 Prevention Key to all cold injuries Proper clothing Avoid tight clothing Layers Inner breathable layer Middle moderate layer Insulating layer Outer layer Water and windproof Awareness of conditions Windchill Weather report Expected conditions Monitor for signs of cold-related illness Ointment and Emollients May increase risk Low level insulation Decreased perception