From the Guidelines
Hypothermia is caused by prolonged exposure to cold temperatures or cold environments where the body loses heat faster than it can produce it, with the primary causes including exposure to cold weather conditions, immersion in cold water, and certain medical conditions that affect temperature regulation, as stated in the 2024 American Heart Association and American Red Cross guidelines for first aid 1. The primary causes of hypothermia include:
- Exposure to cold weather conditions without adequate protective clothing
- Immersion in cold water
- Living in cold homes without proper heating
- Certain medical conditions that affect temperature regulation, such as hypothyroidism, severe trauma, sepsis, and certain medications (including sedatives, opioids, and some psychiatric drugs) Age extremes (very young and elderly) increase vulnerability due to less efficient thermoregulation, as noted in the 2024 guidelines 1. Medical conditions like hypothyroidism, severe trauma, sepsis, and certain medications can impair the body's ability to regulate temperature, while alcohol and drug use worsen hypothermia risk by causing blood vessels to dilate, creating a false sense of warmth while actually accelerating heat loss, as discussed in the Critical Care journal 1. Hypothermia develops when core body temperature drops below 95°F (35°C), leading to progressive dysfunction of the nervous system, cardiovascular system, and eventually all body systems if not treated promptly, as stated in the 2024 guidelines 1. The risk factors for hypothermia in trauma patients include the severity of injury, wet clothing, low transport unit temperature, use of anesthesia, and prolonged surgery, as noted in the Critical Care journal 1. The most effective way to prevent hypothermia is to address the underlying causes and risk factors, and to implement rewarming therapy as early as possible, using passive and active warming strategies, as recommended in the 2024 guidelines 1 and the Critical Care journal 1.
From the Research
Hypothermia Causes
Hypothermia can be caused by various factors, including:
- Accidental exposure to cold temperatures 2
- Therapeutic hypothermia, which is a medical treatment used to lower the body temperature to help reduce the risk of brain damage after a cardiac arrest 3, 4
- Severe hypothermia, which can occur when the body's core temperature drops below 30°C, can cause ventricular fibrillation or asystole 5, 2
Effects of Hypothermia on the Heart
Hypothermia can have several effects on the heart, including:
- Prolongation of the QT interval, which can increase the risk of arrhythmias 2
- Changes in cardiac electrophysiology, which can lead to ventricular fibrillation or asystole 5, 2
- Increased vasopressor requirements, which can be necessary to maintain adequate organ perfusion 4, 6
Treatment of Hypothermia
Treatment of hypothermia typically involves rewarming the body to a normal temperature, and may also include the use of vasopressors or anti-arrhythmic medications to manage cardiac complications 4, 5, 6
- The use of therapeutic hypothermia has been shown to improve outcomes after cardiac arrest, but may also increase the risk of certain complications, such as bleeding or infection 3, 4
- The optimal "dose" of therapeutic hypothermia, in terms of the duration and depth of cooling, is still a topic of debate 6