A hypothermia blanket is a medical device used to lower a patient’s internal body temperature. The blanket can be used to lower the temperature of a patient with an elevated body temperature, or it can be used on a patient with a normal temperature to prevent further damage during a medical crisis. Cold water circulates within the sealed blanket to both absorb excess heat and to provide a cooling mechanism for the body. The blankets are used with specific criteria regarding the temperature goal to be reached and how long the patient is to be kept at the target temperature. Hypothermia can be a dangerous medical condition, and these cooling blankets should only be used under medical supervision.
Induced hypothermia — the purposeful lowering of the internal body temperature — is useful in several medical situations. A hypothermia blanket is sometimes used after cardiac arrest when specific criteria regarding the event have been met. The blankets are used in some cases of perinatal hypoxic ischemic encephalopathy, situations where infants risk brain injury due to a lack of oxygen or impaired blood flow. Hypothermia blankets are also used to cool patients suffering from heat stroke, where the internal body temperature rises above 104 degrees Fahrenheit (40 degrees Celsius).
The body’s normal internal temperature is close to 98.6 degrees Fahrenheit (37 degrees Celsius). Therapeutic hypothermia involves lowering the body temperature to between 90 to 93 degrees Fahrenheit (32 to 34 degrees Celsius). A hypothermia blanket keeps the body at the lowered temperature for varying periods of time, depending on the condition being treated. After treatment, the patient is slowly warmed until the internal body temperature reaches the normal range.
The patient can lay on top or underneath the hypothermia blanket. Occasionally, two blankets are used — one on top as well as one beneath. The patient’s temperature is closely monitored during blanket use. The cooling properties of the blanket are sometimes augmented with invasive cooling methods, such as an infusion of cold, lactated Ringer’s solution, or a catheter to circulate cold saline solution.
Despite their name, hypothermia blankets are not used to treat or prevent hypothermia. Blankets designed to combat hypothermia by either preventing the loss of body heat or raising the body’s internal temperature are called hyperthermia blankets. Some manufacturers offer blankets capable of both lowering and raising the body’s temperature. These hyper/hypothermia blankets use water that is either cooled or heated before being circulated through.