Abstract
Cold and heat injuries are environmental injuries that require acute recognition and appropriate care. The chapter will outline details of both injuries, including diagnosis and management.
Keywords
chilblains, cold injuries, cold-induced bronchoconstriction, cold-induced urticaria, frostbite, frostnip, heat cramps, heat edema, heat exhaustion, heat injuries, heat rash, heat stroke, heat syncope, hypothermia, trench foot
Cold Injuries
1
What causes injuries from cold exposure?
Injuries from cold exposure are due to low air temperatures, water immersion, rain, and wind, which all affect a body’s ability to maintain normothermic temperature. They are divided into low core temperature (hypothermia), freezing (frostbite), and nonfreezing (chilblains, trench foot) injuries.
2
How do you prevent cold injuries?
C – Keep area clean and covered (cover head and neck as they are areas of high heat loss)
O – Avoid overheating (remove layers as necessary)
L – Wear loose clothing and in layers (wicking fabric such as wool with wind-blocking garment)
D – Keep skin dry to prevent heat loss from moisture (waterproof outer layer)
3
What are the common symptoms and signs of cold exposure injuries?
See Table 36.1 .
| Early | Late |
|---|---|
| Shivering | “Stumbles, grumbles, mumbles” |
| Numbness | Decreased or no shivering |
| Pain, burning | Sluggish, poor judgment, confusion |
| Erythema, edema, blistering | Frozen tissue (stiff to touch) |
| Fatigue | Shallow breathing |
4
Who is at high risk?
Individuals younger than 2 years of age or older than 60 years are at highest risk. Elderly persons are especially prone due to age-related decrease in sympathetic nervous system–mediated vasoconstriction, reduced function of sweat glands, and comorbidities. Younger individuals have larger surface area/mass ratios and exhibit greater heat loss. Homelessness and sports activity in inclement environments pose the greatest risk. Specific risk factors include intoxicants (alcohol), psychiatric illness, wet clothing, bare skin, malnutrition, dehydration, fatigue, and sleep deprivation.
5
What temperatures do cold injuries occur at?
Hypothermia is defined as body temperature less than 95°F (35°C) rectally and occurs when heat loss exceeds heat production. Hypothermia can occur at higher temperatures, especially when clothing is wet. Most cold exposure injuries can occur within minutes, depending on the temperature, wind, duration, evaporation, and direct exposure. The Wind-Chill Equivalent Index (WCEI) can be used to assess heat loss from exposed skin.
6
How should you assess and begin management for hypothermia?
If there is concern for hypothermia, begin by removing all wet clothing. Assess mental status, airway, and breathing. If patient is breathing, provide oxygen, obtain vital signs, and place an intravenous (IV) line if able. An accurate core temperature is crucial and ideally is obtained rectally with a thermometer scaled for hypothermia. The core temperature guides treatment, classified as mild, moderate, or severe ( Table 36.2 ). If there is no concern for hypothermia based on core temperature and observation, assess exposed areas and treat.
| Hypothermia | Temperature (Rectal) | Symptoms | Management |
|---|---|---|---|
| Mild | 32°C–35°C (89.6°F–95°F) | Shivering, muscle spasms, lethargy, slurred speech, pallor, low pulse, usually normal blood pressure |
|
| Moderate | 28°C–32°C (82.4°F–89.6°F) | +/- shivering, cyanosis, disorientation, decreased motor skills, muscle stiffness, decreased respiration, low or irregular pulse, low blood pressure |
|
| Severe | <28°C (82.4°F) | Loss of consciousness, rigidity, pulse not palpable, depressed respirations, dilated pupils, pulmonary edema, arrhythmias |
|
7
What is the difference between frostnip and frostbite?
Frostnip is the formation of superficial ice crystals (affects the epidermis only) and causes no tissue damage. Mild frostbite penetrates the dermis, and deep frostbite affects all layers of the skin (permanent damage may occur). Frostbite is due to a localized tissue response whereby electrolyte shifts lead to water crystallization in temperatures below 32°F (0°C), leading to tissue damage. These injuries occur in minutes to hours and typically affect the face, ears, fingers, and toes.
8
What are the major considerations in frostbite injury?
Remove wet, constrictive clothing and assess for hypothermia. If there is a concern for tissue refreezing, do not attempt initial thawing as tissue necrosis may occur (extended freeze preferred to refreeze). Provide adequate anesthesia. Do not massage open blisters or expose area to open heat (stoves, flame, steam, heat packs). Consider transfer for emergency care, especially when affected area is large. The injured body part should be protected with a bulky splint for transport. See Fig. 36.1 .
9
What causes chilblain and trench foot injuries?
Chilblains and trench foot are both nonfreezing injuries ( Table 36.3 ). Prolonged water exposure or sweating from wet-cold conditions (rain, snow, immersion) causes an exaggerated inflammatory response. This causes increased vascular permeability and fluid leakage. Feet (wet socks, footwear) and hands are commonly affected. Wet and constrictive clothing should be removed. Avoid weight-bearing, friction, lotions, or exposing area to extreme heat.
| Chilblain (Pernio) | Trench foot (Immersion Foot) | |
|---|---|---|
| Etiology |
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| Presentation |
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| Management |
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