98 - Cold Injuries Flashcards by dvojnd rivera

Y/N: The human capacity for physiologic adaption to cold is minimal

Yes

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The body can maintain a constant temperature of approximately 37C over a range of external temperatures between

15C and 54C

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Core body temperature is prioritized and maintained largely by controlling

Cutaneous blood flow

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Arteriovenous anastomoses are abundant in

Acral areas

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In prolonged cold exposures, the skin experiences a paradoxical cyclic vasodilation known as _____, to protect against skin necrosis from prolonged vasoconstriction

Hunting reaction of Lewis

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(Slow/Fast) freezing results in extracellular formation of ice whereas (slow/fast) freezing tends to produce intracellular ice

Slow

Fast

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In (slow/fast) rewarming, ice crystals become larger and more destructive

Slow

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Other biologic factors influence vasoconstriction and tissue damage besides temperature

Painful stimuli
Mental stress
Arousal stimuli
Deep breaths

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Individual factors predisposing to cold injuries include

Skin conditions with TEWL (eg, atopic dermatitis)
Physical injuries
Leanness
Low physical fitness level
Fatigue
Dehydration
Previous cold injuries
Sickness
Trauma
Poor peripheral circulation
Poor clothing insulation
Old age

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(Under-/Over-)weight persons are more likely to survive prolonged accidental cold exposure

Over-

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Y/N: Habitually cold-exposed skin develops a more efficient system for shunting blood away from the surface

Yes

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Y/N: Individuals who have experienced previous severe cold injury may have a profoundly delayed or absent hunting reaction in the affected limbs, making them more susceptible to recurrent cold injury with pain, hyperesthesia, or paresthesia

Yes

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Skin cold injuries can be divided into _____ cold injuries

Freezing

Nonfreezing

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Freezing cold injuries

Frostbite
Iatrogenic cold injury
Self-inflicted cold injury

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Nonfreezing cold injuries

Vasoconstriction
Hunting reaction
Immersion foot
Pulling-boat hands
Acrocyanosis
Chillblains
Cold urticaria
Cold panniculitis
Erythromelalgia
Raynaud phenomenon
Sclerema neonatorum
Subcutaneous fat necrosis of the newborn
Livido reticularis
Cryoglobulinemia
Cold agglutinins
Cryofibrinogenemia

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Occurs when tissue freezes after exposure to cold air, liquids, or metals

Frostbite

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The clinical presentation of frostbite falls into 3 categories

Frostnip (mild frostbite)
Superficial frostbite
Deep frostbite

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Frostbite:
Involves only the skin and damage is reversible
Sensation of severe cold progressing to numbness followed by pain
No edema or bleb formation

Frostnip

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Only form of frostbite that can be treated safely in the field with first aid measures

Frostnip

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Frostbite:
Involves the skin and immediately subcutaneous tissues
With pain subsiding to feelings of warmth (sign of severe involvement)
Clear blebs form, accompanied by edema and erythema

Superficial frostbite

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Frostbite:
Extends to the deep subcutaneous tissue
Affected skin becomes deceptively pain free, and the discomfort of feeling cold vanishes
Tissue is totally numb
Large blisters form
Leads to formation of hard, black gangrene

Deep frostbite

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Good prognostic signs of frostbite

Large, clear blebs extending to the tips of the digits
Rapid return of sensation
Rapid return of normal (warm) temperature to the injured area
Rapid capillary filling time after pressure blanching
Pink skin after rewarming

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Poor prognostic signs of frostbite

Hard, white, cold, insensitive skin
Cold and cyanotic skin without blebs after rewarming
Dark hemorrhagic blebs
Early evidence of mummification
Constitutional signs of tissue necrosis, such as fever and tachycardia
Cyanotic or dark red skin persisting after pressure
Freeze-thaw-refreeze injury

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Keystone of treatment of frostbite

Rapid rewarming

Rewarming should be performed in a water bath between 37C and 39C until

The most distal parts of the body are flushed

Surgical debridement is often best delayed until _____ after demarcation

1 to 3 months

Sequelae of frostbite

``` Permanent hypersensitivity to cold Hyperhidrosis SCC Epiphyseal plate damage or premature fusion Frostbite arthritis Ossification of one or both ears ```

Iatrogenic cold injury can be caused by

Cryodestruction using liquid nitrogen

Chemicals that are capable of cold-induced skin injury include the _____ in propellants, refrigerants, and liquefied petroleum gases

Fluorinated hydrocarbons

Perioral or perinasal dermatitis with pyoderma

"Huffer's rash"

Salt rapidly (decreases/increases) the freezing point of water

Decreases

Nonfreezing cold injury occurs when tissues are cooled to temperatures between _____ for hours to days

0C and 15C

Nonfreezing cold injury is historically known as

"Trench foot"

Dryness of the skin, particularly on the lower extremities, during wintertime

Winter xerosis

Vasoconstriction can alter both skin temperature and skin color, resulting in a blue to violaceous _____, a bilateral dusky mottled or confluent red to blue discolotation of the hands, feet, nailbeds, and sometimes the face Persistent and accentuated by cold exposure Trophic changes and pain do not occur Pulses are present

Acrocyanosis

Acrocyanosis must be distinguished from _____, which is clearly episodic, often segmental, and painful

Obstructive arterial disease | Raynaud phenomenon

Defined by the presence of hand edema superposed on acrocyanosis

"Puffy hand syndrome"

Tissues are (more/less) sclerotic in acrocyanosis than in Raynaud phenomenon

Less

In cases of acryocyanosis developing for the first time late in life, an underlying _____ should be exluded

Myeloproliferative disorder

Localized inflammatory lesions caused by continued exposure to cool temperatures (above freezing)

Pernio (chillblains)

Y/N: Pernio shows a genetic predisposition

Yes

Pernio has been described most often in

Temperate regions, where winters are commonly cold and damp

Pernio is more common in

Children Women Persons with low body mass index

A papular form of pernio resembling _____ can occur at all times of the year, usually in crops on the sides of the fingers, often superimposed on a backgroud of acrocyanosis

Erythema multiforme

A peculiar clinical presentation of _____ may occur in young women riding horses for several hours daily during winter

Pernio

Lupus pernio is a variant of _____ and is unrelated to cold injuries

Sarcoidosis

Pernio demonstrating a chronic course (continuous for at least 4 weeks and, in some cases, 8 weeks or longer, or episodic in nature), persistence into warm weather months, and in onset in the elderly may be suggestive of

An associated connective tissue disease, hematologic malignancy, or other systemic condition

Erythematous macules and plaques on the dorsum of the hands and fingers of sailors aboard rowboats

Pulling-boat hands

Rare autosomal dominant condition with onset at an early age and persistence throughout life Urticaria develops when the patient is exposed to generalized cooling

Familial cold urticaria

A mutation in the _____ gene, which is responsible for cold-induced autoinflammatory syndrome, has been identified in familial cold urticaria

CIAS1

Cold urticaria may be a sign of _____ that associates urticaria, deafness, and amyloidosis

Muckle-Wells syndrome

Cold urticaria may be a sign of _____ that associates urticaria, deafness, and amyloidosis

Muckle-Wells syndrome

Relies on using 2 different sufficiently cold, microprocessor-controlled heat-transferring metals to generate a precise skin surface temperature to induce lesions

Peltier effect-based temperature challenge

First-line treatment for cold urticaria

Second-generation H1 antihistamines, up to 4 times the standard dose

Related disorder to cold urticaria with erythema and pain but without urticaria

Cold erythema

Rare autosomal dominant disease characterized by childhood onset of nonpruritic, erythematous patches often accompanied by influenza-like symptoms and leukocytosis after generalized exposure to cold Results of the ice cube tests are negative

Familial polymorphous cold eruption

Nonfreezing injury leading to inflammatory reactions in the subcutaneous fat layers More common in children Most commonly affects the cheeks and legs Eating popsicles is a common trigger

Cold panniculitis

_____ have a higher content of saturated fatty acids in adipose tissue, and this may result in solidification at less-cold temperatures

Infants