Annals of emergency medicine
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Randomized Controlled Trial Comparative Study
Core temperature cooling in healthy volunteers after rapid intravenous infusion of cold and room temperature saline solution.
Studies have suggested that inducing mild hypothermia improves neurologic outcomes after traumatic brain injury, major stroke, traumatic hemorrhage, and cardiac arrest. Although infusion of cold normal saline solution is a simple and inexpensive method for initiating hypothermia, human cold-defense mechanisms potentially make this route stressful or ineffective. We hypothesize that rapid infusion of 30 mL/kg of cold (4 degrees C, 39.2 degrees F) 0.9% saline solution during 30 minutes to healthy subjects (aged 27 [standard deviation (SD) 4] years) will reduce core body temperature to the therapeutic range of 33 degrees C to 35 degrees C (91.4 degrees F to 95 degrees F). ⋯ In this pilot study of healthy volunteers, rapid administration of cold saline solution to awake normothermic volunteers resulted in 1 degrees C (1.8 degrees F) cooling but did not induce a therapeutic plane of hypothermia. This change in core temperature was not accompanied by significant changes in skin temperature. These data suggest that a reduction in core temperature of about 1 degrees C (1.8 degrees F) can be achieved in healthy humans before a thermoregulatory response is triggered and that rapid infusion of cold intravenous fluids is insufficient by itself to overcome this response. The clinically relevant control arm of room temperature saline solution also resulted in mild core cooling.