The distribution of body water in the hypothermic dog.
D'Amato, Henry E
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The direct effect of reduction in body temperature on general metabolism in the dog is one of depression. This is a progressive phenomenon, increasing as body temperature falls. However, in the early stages of hypothermia there simultaneously occurs in certain tissues marked increases in activity which are reflex in nature. The overall metabolism, indicated by total oxygen consumption, at any given time in the cooling procedure is therefore determined by the algebraic sum of the effects of direct depression of some cells and of reflex stimulation of other cells by the cold. The ability of the dog to survive severe reduction in temperature appears to be influenced by the anesthetic agent under which cooling procedure is carried out. In general, ether (by inhalation) interferes least with respiratory and cardiovascular function in deep hypothermia. Of the barbiturates, pentobarbital seems to predispose the dog to death at relatively high body temperatures. [TRUNCATED] The following investigations were made in the dog at normal body temperature and in hypothermia: (A) Hematocrit of blood drawn from the carotid artery was determined by centrifugation in Wintrobe tubes at 3000 revolutions per minute. Plasma water content was determined by drying in an oven at 95°C for forty-eight hours. Plasma protein concentration was determined first by the copper sulfate method of Moore and Van Slyke and subsequently by refractometric measurements. (B) Plasma volume was estimated by the dilution method involving T-1824 (Evans Blue). (C) Thiocyanate space was measured by the dilution technique. [TRUNCATED] The following observations were made: (A) Increases in large vessel hematocrit of 18% to 25% of the normal value were observed. A transient decrease in plasma water was observed at a rectal temperature of 28°C, below which normal content was restored. This rectal temperature corresponds to that at which shivering is near maximal in the hypothermic dog. Plasma protein concentration also increased temporarily, the peak increase occurring at any temperature between 33°C and 23°C. The average increase in plasma protein concentration at 28°C agrees quite well with the average increase in plasma solids, computed from the plasma water decrease observed at the same rectal temperature (B) Plasma volume changes ranged from no change to a decrease of 27% of the control volume, the average change being a decrease of 16%. (C) Changes in thiocyanate space ranged from a decrease of 9% to a decrease of 23% of the control space, the average decrease being 17% of the control space. [TRUNCATED]
Thesis (Ph.D.)--Boston University