What main symptom distinguishes Severe from Moderate Hypothermia?

The main symptom that distinguishes severe hypothermia from moderate hypothermia is amnesia. In moderate hypothermia, patients may still be aware of their surroundings and can exhibit some level of confusion or altered mental status, but they will generally retain some memory and cognitive function. As hypothermia progresses to a severe state, the body's core temperature drops significantly, leading to more profound effects on the central nervous system. This often results in more serious cognitive dysfunction, manifesting as amnesia or unresponsiveness, whereby the individual may not recall events leading up to their hypothermic state or may not respond to stimuli appropriately.

Other symptoms, such as shivering, are typically present in the earlier stages of hypothermia but tend to diminish as the body continues to cool significantly, particularly in severe cases. Cyanosis may be a noted condition associated with poor perfusion and oxygenation at severe hypothermia stages, but it does not specifically distinguish between moderate and severe hypothermia like amnesia does. Thus, the presence of amnesia becomes a clear marker indicating the progression to severe hypothermia.