What is a critical sign of hypothermia?

Cyanosis of the skin is a critical sign of hypothermia because it indicates a lack of adequate oxygenation in the tissues, which can result from reduced blood flow and oxygen delivery as the body temperature drops. In hypothermia, the body attempts to preserve heat by constricting blood vessels, particularly in the extremities, which can lead to this bluish discoloration of the skin. Hypothermia significantly impacts the body's ability to regulate temperature and maintain normal physiological functions, making recognition of its signs, including cyanosis, crucial for prompt medical intervention.

In contrast, increased body temperature would indicate the opposite state, likely fever or hyperthermia. An elevated heart rate might not necessarily be present in early hypothermia since the body’s metabolism and cardiovascular response can be depressed in severe cases. Intense thirst typically relates to dehydration rather than hypothermia itself. Thus, recognizing cyanosis is vital as a key indicator of worsening hypothermia and the need for immediate care.