From the Guidelines
Hypothermia is defined as a core body temperature below 35°C, with stages ranging from mild to severe, and is a medical emergency requiring immediate attention. According to the 2024 American Heart Association and American Red Cross guidelines for first aid 1, hypothermia signs, symptoms, and potential rewarming strategies are categorized into different levels, including cold stress, mild hypothermia, moderate hypothermia, severe hypothermia, and profound hypothermia. The guidelines emphasize that hypothermia occurs when the core body temperature drops below the normal temperature range near 37°C, and individuals may be "cold" or "cold stressed" with temperatures of 35°C to 37°C 1.
Stages of Hypothermia
The stages of hypothermia are characterized by:
- Cold stress: 35-37°C, alert, possibly shivering, and can be treated with passive rewarming methods such as removing from cold environment and protecting from further heat loss 1
- Mild hypothermia: 32-35°C, altered level of responsiveness, shivering, and may require passive and active rewarming methods in tandem 1
- Moderate hypothermia: 28-32°C, decreased level of responsiveness, with or without shivering, and is a medical emergency requiring all available passive and active rewarming methods 1
- Severe hypothermia: <28°C, unresponsive, may appear lifeless, and requires immediate medical attention 1
- Profound hypothermia: <24°C, cessation of shivering, slow heart rate and breathing, and is at high risk for irregular heart rhythm and cardiac arrest 1
Treatment and Prevention
Treatment involves careful rewarming through passive methods like dry clothing and blankets for mild cases, or active methods like heated blankets and warm IV fluids for moderate to severe cases 1. It is essential to recognize the signs and symptoms of hypothermia, especially in vulnerable populations like the elderly, very young children, and those with certain medical conditions that impair temperature regulation, and to provide immediate attention to prevent further heat loss and promote rewarming 1.
From the Research
Definition of Hypothermia
- Hypothermia is defined as a core body temperature less than 35 degrees C (95 degrees F) 2
- It results from prolonged exposure to a cold environment, drugs, and underlying pathologic conditions 2
- Hypothermia is associated with marked depression of cerebral blood flow and oxygen requirement, reduced cardiac output, and decreased arterial pressure 2
Key Characteristics
- Severely hypothermic patients, especially those suffering cardiac arrest, require highly specialized treatment 3
- Pathophysiologic changes occur in the cardiovascular system leading to dysrhythmias, decreased cardiac output, decreased central nervous system electrical activity, cold diuresis, and noncardiogenic pulmonary edema 3
- Cardiac arrest, multiple organ dysfunction, and refractory vasoplegia are indicative of profound hypothermia 3