Homeostatic responses to alterations of blood volume in puppies. I. Hemorrhage

Abstract

of the plasma volume with lowering of the hematocrit. The red cell deficit is replaced later, since stimulation of new red cell production begins well after the whole blood volume has been restored by increase in plasma volume. These responses can be measured in the adult. and an understanding of them provides a rational basis for the diagnosis and treatment of blood loss. In order to assess the magnitude of blood loss and replacement reqlliremchnts in the infant, it has been necessary to rely on uncontrolled clinical observations alone or to extrapolate from experimental data obtained in adult subiects. It is obviously not safe to assume that physiologic responses in the infant and in the adult differ only in magnitlldti or that they are qualitatively unaffected by the processes of maturation. .4s with manv phvsiologic mechanisms which concern the young surgical patient. 110 csp&im&tal c~valuntions of the response to hr,morrhage in the yomng ha1.c been reported in the literature. This report concerns such an evaluation in puppies, The pl~ppy has been srleckd as the experimental animal becauscb abundant hemorrhage data have already been obtained in this and other laboratories “.a in cAzperimc,nts \\-ith the adult dog and are available for comparison . and bc~ause controlled experimental data are not readily obtainable in the hllman infant. T’xperiments in the dog and in man have shoL1.n thcb expansion of the plasma to occur continuously o\‘er a 36 to 18 hour period.:‘,” Diffcrencr~s iri rate, and magnitude of the process in man and in the dog hn\~a heen reported,