Cold Injuries

Question 1

Two common cold injuries & susceptible populations

Answer 1

• Hypothermia & Frostbite
• Populations - winter athletes, moutaineers, elderly, homeless, & employed in cold

Question 2

Causes of frostbite

Answer 2

• Environmental exposure to cold
• Direct exposure to freezing materials…ice packs
• Inhalation of hydrocarbons (upper airway)

Question 3

Frostnip definition

Immersion Foot (“Trench Foot) definition

Answer 3

• Frost = cold induced, local paresthesia that burns/tingles, resolve w/ rewarming
• Immersion = injury to symp. nerves & vasculature, feet erythmatous, numb/pain, covered w/ hemorrhagic bullae

Question 4

What disease progression is this?

Answer 4

Immersion foot/Trench foot

Question 5

Perio definition and lesion descriptions

Answer 5

• Def = acute or repetitive exposure to damp cold above freezing point
• Edematous, red/purple, & may be pruritic and/or painful

Question 6

Frostbite def & what occurs when ice crystals form in tissues?

Answer 6

• Def = tissue cooling w/ vasoconstriction & ischemia
• Abnormal electrolytes; cell dehyd, lysis, & death

Question 7

What can thawing do to frostbite?

Answer 7

• Initiate inflamm pathway = further tissue ischemia, emboli w/in vessels, & thrombi in larger vessel
• Made worse if the injury re-freezes after initial thaw

Question 8

Common symptoms of frostbite

Answer 8

• Cold, numbness, & clumsiness of area
• skin insensate, white/grayish color, & hard or waxy to touch
• Upon rewarming, bullae usually develop

Question 9

1st degree frostbite features

Answer 9

• superficial
• pallor and anesthesia surrounded by erythema
• no tissue infarction

Question 10

2nd degree frosbite features

Answer 10

• Large blisters w/ clear fluid, surrounded erythema & edema
• Seen 24 hrs after rewarming
• No tissue loss

Question 11

3rd degree frostbite features

Answer 11

• Blisters hemorrhagic & more proximal
• Black eschar 1+ week

Question 12

4th degree frostbit depth & extent damage to tissue

Answer 12

• Extend to muscle & bone
• Complete necrosis

Question 13

Should you rub a frostbit area to warm it?

Answer 13

• No, may cause more tissue damage

Question 14

What is the preferred way to rewarm frostbit tissue?

When can you tell if frostbit tissue is thawed?

Answer 14

• Rewarm by placing feet in water heated 37-39° C
• Airdry tissues
• Complete when tissue is red/purple & soft to touch

Question 15

How to care for frostbite wound?

Answer 15

• Non-stick gauze & use pledgets between digits
• elevate=reduce edema
• Blisters
  
  • non hemorr may be debrided
  • hemmorr may be drained, not debrided
• Give tetanus if due
• Surgery if severe
• Avoid Ab = may cause maceration (use if suspected infection however)

Question 16

Thrombolytic therapy to txt frosbite goal?

Answer 16

• Save tissue from microvascular thrombus
• Use tissue plasminogen activator (tPA), can add heparin joint (not by itself)

Question 17

Do you amputate frostbit tissue right away?

Answer 17

No, complete demarcation of necrosis may take 1-3 months

Only amputate right away if signs of sepsis/gangrene

Question 18

5 Ways body loses heat

Answer 18

1. Radiation
2. Conduction (body to object)
3. Convection
4. Evaporation
5. Respiration

Question 19

Normal core body temp & bodies natural reaction to hypothermia

Answer 19

• 37 C
• Shivering & catecholamine production
• Vasoconstriction vessels in periphery to shunt blood to organs & prevent heat loss

Question 20

Common causes of hypothermia

Answer 20

• Metabolism (hypothyroid/-adrenalism)
• Extreme age
• Drug induced (ethanol/sedatives)
• Environment
• Aggressive fluid resuscitation or heat stroke txt

Question 21

Mild hypothermia: body reaction & signs

Answer 21

• Rxn = HTN, shiver, tachycardia/pnea, vasoconstriction
• Signs = apathy, ataxia, cold diuresis, & impaired judge.

Question 22

Temp ranges for normal, mild, moderate, and severe hypo

Answer 22

• normal = 37° C
• mild = 32.2-35° C
• mod = 28-32.2° C
• severe = <28° C

Question 23

Moderate hypothermia signs

Answer 23

• Decreased HR/RR/BP
• Dilated pupils
• No shivering
• J wave
• Paradoxal undressing

Question 24

What is a J Wave?

Answer 24

• Sign of moderate hypothermia
• positive deflection
• Height of deflection is proportionate to degree of hypothermia

Question 25

Severe hypo symptoms/signs

Answer 25

• Apnea
• Coma
• Nonreactive pupils
• Oliguria (no urine)
• Pulm. edema
• Little/no EEG
• Ventricular dysrythmia

Question 26

Preferred thermometer when measuring hypothermia?

Answer 26

Rectal probe thermometer

Question 27

Definitions of methods of rewarming:

1. Passive external
2. Active external
3. Active Internal (Core) Rewarming

Answer 27

1. mild hypo, remove clothing & cover w/ blankets, patient must have intact thermoreg mech, endocrine f(x), & energy stores
2. mod-sev, heat directly to skin, need intact circ, warm trunk before extremities
3. severe
   
   1. Warm IV-saline w/ dextrose heat to 40-45° C
   2. Extracorporeal blood warming - take out blood, heat, then reintroduce, most effective method

Question 28

Most effective temperature reading in rewarming

Answer 28

Esophageal

Question 29

Risks in active external rewarming

Answer 29

• Afterdrop - cold peripheral blood rapidly returns to heart
• Rewarming acidosis - cold, acidemic blood returns to trunk = drops core temp & pH

Question 30

Lab values to check with hypothermia (2 main)

Answer 30

• Glucose
• EKG