Severe (profound) hypothermia (less than 28ºC)

Features of severe (profound) hypothermia (less than 28ºC) include:

• cessation of shivering (in most people)
• loss of consciousness (in most people)
• loss of ability to spontaneously rewarm if the person is removed from the cold environment
• the body adopts the ambient temperature (poikilothermia)
• fixed dilated pupils (ie the patient looks dead)
• reflexes may or may not be present
• cardiac arrhythmia (slow atrial fibrillation progressing to ventricular fibrillation or asystole); risk of spontaneous ventricular fibrillation or asystole is high and exacerbated by movement, so very gentle handling is recommended.

Vital signs can still be detected at core body temperatures of 24ºC; see Rescue and initial resuscitation in hypothermia for advice on clinical assessment required before starting cardiopulmonary resuscitation.