98 - Cold Injuries Flashcards
Y/N: The human capacity for physiologic adaption to cold is minimal
Yes
The body can maintain a constant temperature of approximately 37C over a range of external temperatures between
15C and 54C
Core body temperature is prioritized and maintained largely by controlling
Cutaneous blood flow
Arteriovenous anastomoses are abundant in
Acral areas
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
(Slow/Fast) freezing results in extracellular formation of ice whereas (slow/fast) freezing tends to produce intracellular ice
Slow
Fast
In (slow/fast) rewarming, ice crystals become larger and more destructive
Slow
Other biologic factors influence vasoconstriction and tissue damage besides temperature
Painful stimuli
Mental stress
Arousal stimuli
Deep breaths
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
(Under-/Over-)weight persons are more likely to survive prolonged accidental cold exposure
Over-
Y/N: Habitually cold-exposed skin develops a more efficient system for shunting blood away from the surface
Yes
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
Skin cold injuries can be divided into _____ cold injuries
Freezing
Nonfreezing
Freezing cold injuries
Frostbite
Iatrogenic cold injury
Self-inflicted cold injury
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
Occurs when tissue freezes after exposure to cold air, liquids, or metals
Frostbite
The clinical presentation of frostbite falls into 3 categories
Frostnip (mild frostbite)
Superficial frostbite
Deep frostbite
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
Only form of frostbite that can be treated safely in the field with first aid measures
Frostnip
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
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
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
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
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
