FrostBite & Cold Injury seminar

Question 1

What is cold injury?

Answer 1

Spectrum of injury secondary to heat loss

NONfreezing

• Frost-nip
  
  • reversible superficial freezing; reversible pallor with resultant erythema and pain w rewarming
• Trench foot
  
  • acute prolonged exposure to direct wetness (1-10C); resultant cold sensitivty, blistering, hyperhidrosis
• Chilbain
  
  • chronic prolonged exposure to cool humid air (1-10C); resultant red painful patches, =>chronic vasculitis

FREEZING

• Frostbite: ice crytal formation in tissue

Question 2

What are risk factors for frostbite

Answer 2

• Altered LOC
• military
• homeless
• intoxication
• elderly
• comorbidity - atherosclerosis, PVD, smoking
• improper clothing
• outdoor activity/employment

Question 3

What is the etiology of frostbite?

Answer 3

environmental

• temperature : degree and length of exposure
• conductive heat loss (metal/liquid nitrogen, wet clothes
• convective heat loss (high wind)
• decreased tissue oxygenation (high altitude)

host

• compromised circulation (PVD, tight clothes)
• previous Frostbite
• africains

Question 4

Describe the pathophysiology of frostbite

Answer 4

3 paths

4 phases

MANSONS DOUBLE VASCULAR LESION = direct injury w crystal intra/extracellular + indirect vasopasm/rbc sludge

PATHWAYS

• cellular death
• dermal ischemia
• inflammatory mediators released

PHASES

• Cooling & Freezing
  
  • ​Usual response to cold -> perpheral vasoconstriction to maintain core T ->skin temp drop ->ICE CRYSTAL FORMATION ->skin ischemia
  • DIRECT cellular injury
    
    • ​Intracellular: freezing causes PM lipoprotein disruption->cell death
    • Extracellular: increased ISFosmolarity->cell dehydration
  • INDIRECT
    
    • ​vasospasm and RBC sludge ->ischemia
• Rewarming & Thawing
  
  • ​Crystals melt
  • Edema & reperfusion injury (ROS, TXA2, vasoconstriciton and plat agrgegation)
• Progressive injury
  
  • PG accumulate in blisters
    
    • ​PGE2alpha + TXA2 - vasocontrict + plat agg
    • = increased depth and SA
• Resolution
  
  • ​complete, incomplete or no spontaneous healing

Question 5

How do you classify frostbite injury

Answer 5

• 1st degree = partial thickness freezing
  
  • ​Sx: throbbing, aching pain - TRANSIENT
  • Sn: erythema, edema. desqaumation may occur
• 2nd degree = Full thickness freezing
  
  • ​Sx: Numb
  • Sn: clear blisters, erythema with marked edema, usually develop wihtin 8hrs
• 3rd degree = FT with Subcutaneous freezing
  
  • ​Sx: thrombbing aching shooting pain
  • Sn: blueish violet discoloration, hemorrhagic blisters, block of wood appearance
• 4th degree = FT with Sq and tendon/muscle/bone
  
  • ​Sx: numb, +/- jt pain
  • Sn: mottled, deep red/cyanotic then black areas, no edema

Question 6

How do you manage frostbite?

Answer 6

• Hx: environmental etiologies, duration, comorbidities
• PE: 6-24hrs for clear blisters- wiat 48hrs before classifying

TREATMENT

• IN field - NO rewarmign unless can be competed - trasnfer
• In ER
  
  • ABCs
  • rapid rewarm - 40-42C bath 20-40mins with AROM joints
  • analgesia, tetanus, elevation
  • escharotomy
• Acute
  
  • Debride clear blisters (contrain TXA2)
  • Aloe vera q6h (antiPG, stops thromboxane synthase)
    
    • *preserves subdermal plexus
  • NSAIDS 12mg/kg q6h (antiPG)
    
    • COX inh - reduced PGE2 production
  • Wound care dialy - flamazine BID
  • Analgesia
  • antibiotics if indicated
  • thrombolysis - if risk lifealtering amputation and no CI to TpA
• Late
  
  • allow tissue to mummify, eschar to separate
  • dressing daily
  • debride 1-3mths
  • Only timeto amputation early ->frank infection

Question 7

What are complications of frostbite

Answer 7

• amputation
• Skin and NV
  
  • hyperhidrosis
  • altered pigment
  • cold sensitivity
  • chronic pain
• Muscle/bone
  
  • HO
  • intrinsic muscle atrophy
  • stiffness

Question 8

What is hypothermia

Answer 8

Core temperature <35C

Mild: 32-35

Moderate 32-28

Severe <28

* lifethreatening hypothermia is below 32

Question 9

What is the etiology of hypothermia

Answer 9

Loss of heat

• environmental
• iatrogenic (CV pump/shunt)
• skin disorder (psoriasis, burns, exfoliative dermatitis)
• vasodilation (Etoh,drugs)

Reduced heat production

• malnutrition
• endocrine (hypoT,P,adrenal)

Reduced perfusion control

• DM
• SCI
• CVA/SAH

Other

• sepsis, pancratitis, uremia

Question 10

How do you manage hypothermia

Answer 10

• Hx: environment, comorbidities, confusion
• PE
  
  • CNS: confusion->coma
  • CV: Afiv/Vfib/asystole/bradycardia
  • PVS: constricted ->central volume overload ->cold diuresis ->hypovolemia->RTdysfx->more diuresis
  • Resp: hyperventilation->meduallry depression->resp depression, noncardiogenic pulm edema
  • MSK: paresis
  • Hematologic: Hb curve shift left - less offloading at tissue, DIC, MetACid + Resp Alk
• Treatment
• A- airway Cspine
• B- breathing - vent (PEEP for noncardiogenic pulm edema)
• C- chest compression + volume expansion (PRIOR to rewarm)
• D- Defib only once
• E - Rewarming
  
  • PASSIVE - remove wet clothes, blankets
  • ACTIVE
    
    • External: heat lamp on core, heating pads, water bath 42-45
    • Internal: 45C iv fluid, vent hum air 47C, Lavage gastric NG/colonic/rectal, foley/peritoneal/pleural, Ecmo
• If mild (32-35) -> passive and active external
• if moderate (32-28) ->passive+active external COre only
• if severe - active internal directly
  
  • iv lfuids
  • vent warm air
  • NG
  • foley
  • ECMO
  • pleural/peritonela lavage
• continue until >35