Hypothermia is defined as the condition in which the core body temperature is 35°C (95°F) or below, as measured by a rectal thermometer probe placed at least 6 inches into the rectum. Hypothermia can be viewed as a decrease in core temperature that renders a patient unable to generate sufficient heat production to return to homeostasis or normal body functions.

Hypothermia can occur in many different situations, resulting from cold ambient air, cold-water immersion or cold-water submersion as well as a normal consequence of a patient’s systematic disorders, including hypothyroidism, hypoadrenalism, trauma, etc.


The clinical management of hypothermia is based on the following three ranges of rectal body temperature[1].

  • Mild hypothermia: above 35°C to below 32°C (95 to 89.6°F).
  • Moderate hypothermia: 32°C to 28°C (89.6 to 82.4°F).
  • Severer hypothermia: below 28°C (below 82.4°F).
  • Profound hypothermia: below 20°C (below 68°F) – apparent death/cardiac arrest.

Hypothermia patients should be kept in a horizontal position when possible, and certainly during initial care, to avoid aggravating hypotension and afterdrop. It is recommended to assess for breathing and a pulse first, and then follow the approach shown in Figure 1. Life Support Guidelines for Treatment of Hypothermia[2].

Passive rewarming is adequate for patients with mild hypothermia. However, it is highlighted in the guidelines that patients with moderate to severe hypothermia need active rewarming that is generally limited to procedures performed in an ED, operating room, or critical care unit. Passive rewarming procedures alone for these patients are totally inadequate to increase core temperature in the prehospital setting. Therefore, if possible, active rewarming procedures with warm, humidified oxygen and warm IV fluid infusion should be initiated during transport in a way that will prevent further heat loss.

It is important to notice, though, that when it comes to treating a critically injured trauma patient, blood or IV fluid that is infused to the patient should be warmed up to prevent hypothermia regardless the core temperature of the patient.



[1] Presented by the Wilderness Medical Society

[2] Modified from Figure. 19-10, PHTLS: Prehospital Trauma Life Support, 9th edition.

Source: National Association of Emergency Medical Technicians (U.S.) & American College of Surgeons. (2020). PHTLS: Prehospital trauma life support.