The adrenergic, respiratory, and cardiovascular effects of core cooling in humans. Frank, Steven M., Michael S. Higgins, Lee A. Fleisher, James Sitzmann, Hershel Raff, Michael J. Breslow. Assistant Professor, Department of Anesthesiology and Critical Care Medicine, The Johns Hopkins Medical Institutions, Baltimore, Maryland, Assistant Professor, Department of Anesthesiology, Vanderbilt University School of Medicine, Nashville, Tennesse, Professor and Chair, Department of Surgery, Georgetown University, Washington, D.C., Department of Medicine, St. Lukes Medical Center, The Medical College of Wisconsin, Milwaukee, Wisconsin, Department of Anesthesiology and Critical Care Medicine, The Johns Hopkins Medical Institutions, Baltimore, Maryland
APStracts 3:0324R, 1996.
The adrenergic, respiratory, and cardiovascular responses to isolated core cooling were assessed in awake human subjects. Mild core hypothermia was induced by intravenous infusion of 30 ml/kg or 40 ml/kg of cold saline (4 C) on two separate days. A warm intravenous infusion (30 ml/kg, 37 C) was given on a third day as a control treatment. Mean norepinephrine concentration increased 400% and total body oxygen consumption increased 30% when core temperature decreased 0.7 C. Mean norepinephrine concentration increased 700% and total body oxygen consumption increased 112% when core temperature decreased 1.3 C. Core cooling was associated with peripheral vasoconstriction and increased mean arterial blood pressure while heart rate was unchanged. Plasma epinephrine and cortisol concentrations were unchanged during core cooling. There were no changes in any measured parameter with the warm infusion. These findings suggest that mild hypothermia induced by isolated core cooling is associated with an adrenergic response characterized by peripheral sympathetic nervous system activation without a significant adrenocortical or adrenomedullary response. The respiratory and cardiovascular responses to core cooling are characterized by a shivering-induced increase in metabolic rate, norepinephrine-mediated peripheral vasoconstriction, and increased arterial blood pressure. 

Received 29 March 1996; accepted in final form 6 August 1996.
APS Manuscript Number R187-6.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 19 September 1996