No prospective, controlled studies comparing the various rewarming modalities have been done in humans. Therefore, firm guidelines for therapy cannot be given.
Patients with mild hypothermia, who are still in the "excitation" stage, generally improve spontaneously, as long as endogenous heat production mechanisms are functional. In addition, at temperatures above 30°C (86°F), the incidence of dysrhythmias is low, and rapid rewarming is rarely necessary.
By far the most important consideration is the patient's cardiovascular status; a secondary consideration is the presenting temperature. Some feel that patients with a stable cardiac rhythm (including sinus bradycardia and atrial fibrillation) and stable vital signs do not need rapid rewarming, even if the temperature is very low. They recommend passive rewarming and noninvasive internal modalities (e.g., warm moist oxygen and warm intravenous fluids) in this setting. Others argue that profoundly hypothermic patients, even if currently "stable," are at risk of developing life-threatening dysrhythmias. They recommend rapid rewarming until the temperature has reached 30 to 32°C (86-89.6°F) to minimize the time period during which dysrhythmias may develop. The relative merits of each approach have not been studied.
Patients with cardiovascular insufficiency or instability, including persistent hypotension and life-threatening dysrhythmias, need to be rewarmed rapidly. The best method remains to be definitively determined. Extracorporeal techniques offer many advantages but are often unavailable. If extracorporeal rewarming is not available, multiple other rewarming modalities can be used simultaneously.
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This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.