John Hatzenbuehler MD FACSM Team Physician Course San Antonio, TX

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1 John Hatzenbuehler MD FACSM Team Physician Course San Antonio, TX

2 Canadian Temperature Conversion chart 50 Fahrenheit (10 C) New Yorkers try to turn on the heat. Canadians plant gardens. 40 Fahrenheit (4.4 C) Californians shiver uncontrollably Canadians Sunbathe. 35 Fahrenheit (1.6 C) Italian Cars won't start Canadians drive with the windows down 32 Fahrenheit (0 C) Distilled water freezes Canadian water gets thicker. 0 Fahrenheit ( C) New York City landlords finally turn on the heat. Canadians have the last cookout of the season Fahrenheit (- 40 C) Hollywood - disintegrates. Canadians rent some videos Fahrenheit (- 51 C) Mt. St. Helen's freezes. Canadian Girl Guides sell cookies door- to- door Fahrenheit (- 73 C) Santa Claus abandons the North Pole Canadians pull down their earflaps. 173 Fahrenheit (- 114 C) Ethyl alcohol freezes. Canadians get frustrated when they can't thaw the keg Fahrenheit (- 273 C) Absolute zero; all atomic motion stops. Canadians start saying "cold, eh? " Fahrenheit (- 295 C) Hell freezes over. The Leafs win the Cup*

3 Objec&ves Describe the physical changes associated with the stages of hypothermia Understand prevention and treatment of cold water immersion Identify frostbite and discuss appropriate treatment recommendations

4 At what temperature are the fastest marathons run? 45 F 50 F 55 F 60 F 45

5 Demographics of Hypothermia 600 deaths/year US 50% age > 65 Majority in an Urban setting Primary v. Secondary may be judgment call Sepsis Hypoglycemia Hypothyroid Addisons Drugs

6 Hypothermia < 35 C core temp Conduction (swimming) Convection( biking) Radiation ( any outdoor activity in Maine) Evaporation ( sweating, triathlon, tough mudders)

7 Physiologic response to cold Behavioral Get out of the cold Put your hat on Peripheral Vasoconstriction Shivering Max at core temp of 35 C Need fuel to shiver 2X+ basal metabolic rate Do hypoglycemics shiver?

8 What do athletes do? Just keep going Go a little faster to warm up. Result : They feel miserable but Finish the race with great stories to tell.

9 When the cold wins: the Downward Spiral Cold Diuresis Dehydration Increase Respiratory rate Dehydration Cold hand and feet Clumsiness, falls Disorientation Bad decisions, paradoxical undressing

Hypothermia Mild: 35-32 C : shivering mumbles, stumbles, fumbles Moderate: 32-28C Shivering stops

10 Hypothermia Mild: C : shivering mumbles, stumbles, fumbles Moderate: 32-28C Shivering stops Bradycardia Unresponsive Spontaneous v- fib Severe: 28C Coma, unable to resuscitate until rewarmed

11 Osborne Wave

12 Stage Mild Zone Core Temperature 36 C 96.8 F Characteristics Increase in metabolic rate, tachycardia, CNS depression Maximum shivering thermogenesis Amnesia, dysarthria, and poor judgment develop; normal blood pressure; maximum respiratory stimulation Ataxia and apathy develop

13 Stage Moderate Zone Core Temperature 32 C 89.6 F Characteristics Stupor; 25% decrease in oxygen consumption Extinguished shivering thermogenesis Atrial fibrillation and other arrhythmias develop; poikilothermia; pulse and cardiac output 2/3 of normal; insulin ineffective Progressive decrease in level of consciousness, pulse and respiration; pupils dilate Decreased ventricular fibrillation threshold; 50% decrease in oxygen consumption and pulse

14 Stage Severe Zone Core Temperature 27 C 80.6 F Characteristics Loss of reflexes and voluntary motion Major acid-base disturbance; no reflexes or response to pain Cerebral blood flow one-third of normal; cardiac output 45% of normal; pulmonary edema may develop No corneal or oculocephalic reflexes Lowest resumption of cardiac electro-mechanical activity,; pulse 20% of normal

15 Stage Profound Zone Core Temperature 19 C 66.2F Flat EEG Asystole Characteristics Lowest infant accidental hypothermia survival Lowest adult accidental hypothermia survival Lowest therapeutic hypothermia survival

16 Immersion Incident

17 A Dunk in the Drink You are an otherwise intelligent person who has gone out alone in your kayak one May morning. You round a point just as a steep wind driven wave hits you broadside and your kayak flips forcing you to wet exit into the bay. You are 100 feet from a rocky shore. What factors determine your survival?

18 Immersion Incident I ain t drowned yet! Air and Water Temperature Your clothing Your body type Wind Velocity/Waves Your PFD Airway freeboard Your state of mind Panic?

19 Water Temperature Thermoneutral F Significant hypothermia risk < 77 F Open water swim not sanctioned < 59F cooling rate deg/min Water Temp deg C

20 Effect of Clothing with Immersion in 7 deg C water Coveralls : 3 C / hour Wet Suit: 1 C / hour Dry Suit: 0.5 C / hour

21 Wind Velocity and Waves Accelerates cooling Cold water leaks in clothing Reduces Airway freeboard Reduces ability to swim Wind chill Is it better to stay in the water or to try and get up on the boat?

22 Dddddon t Ppppppanic!! Swimming Asynchrony HELP/Huddle Positions

23 The 1:10:1 rule of cold water immersion 1 minute to collect yourself and to steady your breathing 10 minutes to swim 1 hour while you are still awake

24 Field Notes Prevention Clothing check No open water swim with water temp < 59 F No cross country ski race <4F Early recognition: Watch for the umbles Have adequate monitors No hidden areas

25 Management of Hypothermia Handle gently Risk of v- fib Keep supine if water immersion Water squeeze External warm packs/ hypothermia wraps are safe Stabilize temperature If frostbite and hypothermia Hypothermia first

26 The Cold and Dead Controversy Dead and Cold exists Other lethal injuries Inability to ventilate or compress chest Frozen blood Serum K > 10 Temp < 12 C ph < 6.5

27 Who Gets Frostbite?

28 n Winter Hikers

29 Urban Homeless

30 Cold Weather Workers

31 The Impaired and Unprepared Altered Mental Status Dementia Psychiatric Illness Alcohol Diabetes Neuropathies Vehicle Breakdown

32 Athletes

33 Adapta&on by training in the cold Cold recovery test How fast your hand rewarms after 10 minutes in 10 C water. Significant improvement after 15 months of cold weather training. n Hand cold recovery response before and after 15 months of military training in a cold climate Bransrom et al; Av. Space, Env Med Sept 08.

Cultural Adapta&on: Clothing 3 Layers Inner: wick

Windbarrier and wick Focus on keeping the core warm

Gloves No Tight Boots/Shoes Protective layer of warm

34 Cultural Adapta&on: Clothing 3 Layers Inner: wick away moisture Middle: Insulator and wicking Outer: Windbarrier and wick Focus on keeping the core warm Head, Trunk Allow unimpeded circulation Mittens v. Gloves No Tight Boots/Shoes Protective layer of warm air Allow moisture to pass outward Allow for warmth when wet

35 Frostbite True tissue freezing 25 F at tissue level Lowered freezing point Salt, protein Heat loss sufficient to permit ice formation in tissues Ice crystals kill cells

36 What is the most common cause of frostbite seen in a clinic seu&ng?

37 Ice Pack Injuries

38 Classifica&on of Frostbite Injuries Frostnip: Superficial (no tissue loss) Severe or deep (with tissue loss) Some indication after rewarming May take weeks to determine

39 What Determines the Severity of the Injury? Extent and duration of freezing injury Direct contact with thermal conductors* Windchill index Hypothermia Bare skin Thaw/refreeze *You can get Frostbite if the ambient temp is above freezing

40 Prognos&c Signs Favorable Normal sensation, color, warmth Edema formation within 3 hours Early formation of clear blebs to digit tips Unfavorable No edema formation Late formation of small, dark blebs

42 2 nd Degree after rewarming

43 n Field n E.D. n Rewarmed n 90 days

45 Pre- hospital Care Supportive care for trauma. Dehydration Treat hypothermia first!!! Avoid heat loss If extremity frozen and rescue near keep frozen unless warm- water thaw available with no danger of refreezing If already thawed avoid refreezing Oxygen if available

Treatment: Rewarm Rapidly Water temp 42 C Circulating Bath 20 30 Minutes

46 Treatment: Rewarm Rapidly Water temp 42 C Circulating Bath Minutes Feel for skin pliability/ red purple color prolonged heating no added benefit.

47 tpa and Frostbite n Initial appearance

48 Angiograms pre and post tpa n Left pre n Right pre n Left post n Right post

49 n Vapor barrier boots/ rubber gloves Immersion Injuries (NFCI) degrees 12 hours to 2 days Long term pain sequelae

50 Frostbite preven&on spor&ng events. Schedule winter events mid day Consider reschedule if ambient < - 20 C (4 F). (Warmer if Windy) Frostbite incidence <5% at 5 degrees F Communicate proper clothing, hydration and nutrition to athletes. Rewarming stations Avoid shower or shave until after event. Avoid lotions on exposed skin Avoid unsupervised areas of the event No Smoking, no caffeine?

51 Pulmonary Cold induced Bronchospasm Dry airways with osmosis induced edema Up to 40% Olympic athletes Worse at indoor venues Difficult to prevent Treat with: Albuterol Ipatropium Inhaled Steroids

52 Other Cold Injuries Acquired Cold Urticaria Also familial type Rare anaphylaxis Ice cube test Potential serious reaction in cold water

53 Summary Hypothermia <35 C Cold immersion bad. Preparation, anticipation, prevention Frostbite more common that you may suspect Circulation baths ideal Avoid re- frezzing Consider frostbite prevention strategies

54 Thank you

Cold Weather Emergencies

Cold Weather Emergencies Introduction Medical emergencies can result from exposure to heat or cold. Certain populations are at higher risk for heat and cold emergencies. Children Older people People with