PCL1- Management of Accidental Systemic Hypothermia

Passive and Active External Rewarming Methods

-Patients with mild hypothermia (rectal temperature > 33 °C) who have been otherwise healthy usually respond well to passive and active external warming.
-Passive external rewarming involves removal of cold wet clothing and covering the patient with blankets to prevent further heat loss.
-The patient will rewarm due to the body's internal heat production through shivering and increased metabolism. -
-Active external rewarming is highly effective and safe for mild hypothermia. This is a noninvasive method of applying external heat to the patient's skin. Examples include warm bedding, heated blankets, heat packs, and immersion into a 40 °C bath. -Warm bath immersion limits the ability to monitor the patient or treat other coexisting conditions.
-Afterdrop can be lessened by active external rewarming of the trunk but not the extremities and by avoiding any muscle movement by the patient.



Active Internal (Core) Rewarming Methods

-Active internal core rewarming methods are required for patients with core temperatures of < 33 °C.
-Patients with milder degrees of hypothermia may also benefit from these methods. -Warm humidified oxygen (43–46 °C) is an easy, safe, and highly effective method. -Warmed intravenous saline infusions (43 °C) should be used instead of lactated Ringer solution.
-Volume resuscitation is needed to prevent shock as vasodilation occurs during rewarming.
-Other methods (including warm solution lavage of the stomach, colon, thoracic cavity, peritoneum, or bladder; extracorporeal blood rewarming by cardiopulmonary, arteriovenous femorofemoral, or venovenous bypass; and hemodialysis) are based on the availability of equipment and skilled personnel.
-Endovascular warming devices are a less invasive alternative than extracorporeal methods but are not widely available in hospitals.


-For patients with core temperature < 30 °C, treatment includes active rewarming, cardiopulmonary resuscitation (CPR), one shock attempt for dysrhythmia, and withholding of intravenous medications.
-Once the core temperature reaches 30 °C, cardiac medications can be given but at longer than standard intervals because metabolism is slowed and there is a risk of toxic accumulation as circulation is restored.
-Defibrillation may be performed as needed. Resuscitative efforts should be continued until the patient's core temperature increases to at least 32 °C.

SOURCE: Nemer J. , Current Medical Treatment and Diagnosis, Chapter 37: Disorders Related to Enironmental Factors