ENVIRONMENTAL EMERGENCIESPATHOPHYSIOLOGY
■ ↓Core body temperature →peripheral vasoconstriction (to decrease con-
vection) and ↓HR (to decrease blood flow to periphery) →peripheral
ischemia and cold injury.
Chillblains
Chilblains is mild tissue injury from repetitive exposure to dry cold at non-
freezing temperatures. It characteristically involves the dorsum of hands and
feet, but may also involve face, ears, and thighs.
SYMPTOMS/EXAM
■ Painful/inflamed skin lesions that are pruritic and erythematous.
■ May evolve to plaques, blue nodules, and ulcerations.
TREATMENT
■ Rewarming and symptomatic treatment
Trenchfoot
Trenchfoot occurs with exposure to wet cold at freezing temperatures
(0–10°C) over several hours to days.
SYMPTOMS/EXAM
■ Before rewarming (prehyperemic stage): Feet appear cold, mottled, pale
■ After rewarming (hyperemic stage): Feet are red, painful, and swollen
TREATMENT
■ Carefully wash and dry feet, then wrap with warm clothing.
■ Elevate feet.
■ Nonweight-bearing, until improved
COMPLICATIONS
■ Wet gangrene, if untreated
■ Late sequelae (posthyperemic stage): Cold sensitivity, pain and numbness,
atrophy, weakness
Frostnip
Frostnip is a superficial freezing injury without tissue loss or tissue destruction.
It typically involves exposed surfaces (face, hands).
TABLE 13.7. Mechanisms of Heat Loss/Gain
Conduction Direct physical contact with another surface →heat loss or gain (eg, ice
packs, heating pad)Convection Heat transfer via circulating air or water molecules (eg, wind chill)Radiation Heat transfer by electromagnetic waves (eg, poor insulation in cold
environment)Evaporation Heat transfer as water is vaporized (eg, sweating, breathing)