If further care is required, different techniques may be used to rewarm the body based on the severity of the hypothermia:
Passive External Rewarming
Passive external rewarming (PER) is typically used to treat mild hypothermia. It simply involves placing the individual in an appropriately warm environment, covered in insulation, and gradually raising the core body temperature a few degrees every hour.
Active Core Rewarming
PER cannot be used if a person’s temperature drops below 86 degrees. It is at this stage that spontaneous shivering will stop and the body will no longer be able to increase the temperature on its own. By that point, the heart will be unstable and the use of external heat will only increase the risk of arrhythmia.
There are several ways this can be done:
- Feeding warm, humidified air into the lung with an oxygen mask or breathing tube
- Administering warm fluids intravenously (into a vein)
- Irrigating the abdomen (peritoneal cavity) or the space around the lungs (pleura) with warm salt water every 20 to 30 minutes
- Administering warm fluids into the bladder with a Foley catheter
- Rewarming the blood with a hemodialysis machine or a heart bypass machine
- Using diathermy, a technique in which low-frequency microwave radiation can deliver heat to deeper tissues
Generally speaking, someone with hypothermia is released home after treatment is complete if his or her body temperature was above 89.9 degrees at the time of diagnosis.
If body temperature was ever below 89.9 degrees, hospitalization and monitoring for no less than 24 hours, until vital functions are stabilized, is required.