Hypothermia and Frostbite

Ovid: 5-Minute Sports Medicine Consult, The

Hypothermia and Frostbite
Rania L. Dempsey
Craig C. Young
  • Frostbite:
    • Severe local cold-related injury resulting in freezing of soft tissue:
      • Superficial: Partial or complete freeze of skin
      • Deep: Involvement of skin and underlying tissue (may include muscles, vessels, nerves, fat, and bone)
  • Hypothermia:
    • Systemic cold injury, classified as:
      • Mild: Core body temperature 32–35°C (90–95°F)
      • Moderate: 30–32°C (86–90°F)
      • Severe: <30°C (86°F)
  • True incidence of hypothermia and frostbite is unknown in athletes:
    • Mild cases of both are likely common in cold environments.
    • Hypothermia reported in up to 69% of athletes in cold water swimming events (1).
  • Annual incidence of hypothermia-related deaths 4 per 1,000,000 general population in the U.S. (2):
    • More common in men (67% of hypothermia deaths) and those aged ≥65 yrs (49% of hypothermia deaths)
Risk Factors
  • Hypothermia:
    • Environmental factors: Cold temperature, wind chill, prolonged exposure, high altitude
    • Wet clothing (increases heat loss 2–5 times) or immersion (increases heat loss 10–25 times)
    • Fatigue
    • Low body fat
    • Alcohol use (inhibits shivering, enhances heat loss through peripheral vasodilation, and may lead to false sense of warmth)
    • Extremes of age (very young or old)
    • Underlying medical disease (eg, sickle cell anemia, peripheral vascular disease, diabetes, seizure disorder, hypothyroidism)
    • Use of neuroleptic drugs
  • Frostbite:
    • Environmental factors:
      • Cold temperature, wind chill, prolonged exposure, high altitude
        • Risk of frostbite is <5% with temperatures >5°F (-15°C), but significant risk of frostbite increases with temperatures ≤18°F (-27°C) (3).
    • Wet clothing (increases heat loss 2–5 times) or immersion (increases heat loss 10–25 times)
    • Prior cold injury
    • Petroleum or oil lubricants
    • Constrictive clothing
    • Smoking
    • Vasospastic disorders, ie, Raynaud's syndrome
General Prevention
Best treatment for hypothermia and frostbite is prevention (3)[C]:
  • Event planning based on the potential temperature ranges
  • Proper clothing, including hats, mittens, and multiple layers, as necessary
  • Avoid alcohol and other mood-altering drugs.
  • Recognize the signs and symptoms of hypothermia that indicate a need to seek shelter (shivering, slurred speech, somnolence)
  • Frostbite:
    • Fluids in body tissues and cellular spaces freeze and crystallize.
    • Cyclic vasodilation and vasoconstriction contribute to hypoxia/ischemia of affected tissue
    • Severe or prolonged exposure can lead to irreversible tissue damage.
  • Hypothermia:
    • Body heat is lost to the environment at a rate that overwhelms normal temperature homeostasis, resulting in decreased core body temperature.
    • With decreasing temperature, heart rate, cardiac output, and cerebral blood flow decrease:
      • May lead to cardiac rhythm disturbance and death
  • Frostbite:
    • Skin may appear erythematous and swollen, or waxy, white, yellow, or blue-purple.
    • Vesicles/blisters may be present.
    • Patients with superficial frostbite complain of numbness and pain in affected area, but in severe/deep frostbite, pain may be absent.
  • Hypothermia:
    • Mild: Patient displays shivering and mild mental status changes, including confusion, amnesia, dysarthria, and ataxia.
    • Moderate: As core temperature declines, patient may develop severely impaired judgment or stupor, loss of deep tendon reflexes, loss of shivering with muscle rigidity, and cardiac arrhythmias.
    • Severe: Patient may have dilated pupils and appear comatose, with nearly undetectable BP and respiration.
  • Duration and severity of cold exposure (prolonged exposure to very cold temperatures increases risk of severe frostbite or hypothermia)
  • Recent alcohol or drug use (impairs judgment and increases susceptibility to cold injury)
  • History of cold water immersion (wet clothing and skin significantly increase continued heat loss)
  • Underlying medical conditions (increases risk of severe frostbite or hypothermia)
  • Pain in affected area suggests superficial vs deep frostbite.
Physical Exam
  • Measure core body temperature:
    • For greatest accuracy, should be taken rectally with a thermometer capable of measuring hypothermic temperatures (4)[A]
  • Assess pulse and cardiac rhythm:
    • Tachycardia may be seen with mild hypothermia.
    • May progress to bradycardia, atrial fibrillation, or ventricular fibrillation with more severe hypothermia
    • In severe hypothermia, may be difficult to manually palpate pulse
  • Assess mental status:
    • Degree of mental status alteration correlates with severity of hypothermia
  • Perform complete neurologic examination:
    • Intact sensation to pinprick indicates a better prognosis for patients with frostbite.
    • Decreased muscle coordination, delayed deep tendon reflexes, and slowed pupillary reflexes suggest more severe hypothermia.
    • Focal neurologic deficit suggests etiology of mental status changes other than hypothermia.
  • Inspect appearance of skin:
    • Cold, yellow-white, or purple skin suggests frostbite.
    • Tissue pliability suggests superficial frostbite; hard tissue without pliability suggests deep frostbite.
Diagnostic Tests & Interpretation
  • EKG: May see tachycardia; bradycardia; atrial fibrillation; ventricular fibrillation; prolonged PR, QRS, and QT intervals, and J waves (positive deflection occurring at junction of QRS complex and ST segment)
  • Electrolytes and basic chemistries: Hypothermic patients are at high risk for acid-base disturbances.
Differential Diagnosis
  • Frostbite:
    • Frostnip: Freezing injury to superficial skin layers
    • Trenchfoot: Swelling, cyanosis, and erythema of extremity without freezing of tissue
    • Chilblains: Local cold-related erythematous skin lesions
  • Hypothermia:
    • Altered mental status from metabolic abnormalities, alcohol/toxic ingestion, or closed head injury


  • 991.0 Frostbite of face
  • 991.3 Frostbite
  • 991.6 Hypothermia

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