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Key Clinical Questions

  • image What are the signs and symptoms of hypothermia?

  • image What are the most common causes of hypothermia?

  • image Does intoxication associated with hypothermia suggest a better or worse prognosis?

  • image What are the dangers associated with hypothermia?

  • image Who is most likely to die from hypothermia?

CASE 94-1

A 54-year-old man was brought to the hospital after being found unresponsive in his apartment. His family noted that he had been recently hospitalized for pneumonia and had been released from the hospital 3 days earlier. The ambient temperature of the apartment was normal per the EMS report.

His temperature was 32°C, his heart rate was 50 beats/min, his respiratory rate was 14 breaths/min, and his blood pressure was 90/60 mm Hg. His head and neck, cardiovascular, and abdominal examinations were normal. His skin was cool but warmer than expected given his core temperature; pulses were present in all extremities. There were decreased breath sounds and egophony in the right lower lobe; the signs of consolidation were confirmed by chest x-ray.

What is the cause of this man’s mental status changes and what is his prognosis?

Vital signs are routinely measured for all hospitalized patients on admission, during nursing shifts and when infusions are being administered. Clinicians should be able to recognize when abnormal temperatures require immediate action to avoid adverse consequences that may be potentially life-threatening.


Core body temperature is tightly regulated between a normal diurnal range of 36.0°C and 37.5°C. Temperatures below 36.0°C are considered abnormal. Patients admitted to the inpatient service frequently have temperature abnormalities on admission or may develop them during the hospital stay. Because of potential life-threatening causes, it is essential to obtain an accurate measurement of core body temperature. Temperature is most accurately measured by the gold standard methods of intravascular, esophageal, or bladder thermistors. Because these are logistically difficult, temperature is most commonly measured by rectal, oral, and tympanic membrane measurements. Axillary measurements routinely underestimate core body temperature and are not recommended. Interpretation of oral measurements requires consideration of influences that affect the results such as eating, drinking, breathing devices, tachypnea, and mouth breathing. Rectal temperatures may be two to three tenths of a degree Celsius higher than actual core body temperature. Infrared cutaneous, aural, and oral thermometers are not reliable in patients with hypothermia. The most accurate aural method is a thermistor probe in direct contact with the tympanic membrane, although the ear canal must be free of cerumen and debris for this to be precise.


Exposure hypothermia is defined as an unintentional fall in core body temperature below 35.0°C from exposure to a cold environment. The most common cause is lack of shelter, warm clothing, or heat during the winter months. When environmental exposure to cold ambient temperatures is not obvious, making the diagnosis can be challenging because the ...

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