A study of the effects of hyperventilation, hypothermia and urea administration on circulation and cerebrospinal fluid pressure in the dog was made using urea in doses of 2 g./kg. and 6 g./kg. Studies were made in 10 dogs at normal body temperatures and after lowering the temperature to 28-30 C. The dose of urea that brought about a significant reduction in cerebrospinal pressure in normothermic dogs lay between 1 g. and 2 g./kg. In a previous study the dose which brought about an equal response in cooled animals lay between 1/3 g. and 1 g./kg. Adverse effects on the cardiovascular indices of ECG, blood pressure or cardiac output were not seen at either normal or lowered body temperature in either study.
(C) 1965 American Society of Anesthesiologists, Inc.