Restoration of Blood Volume Following Standard Sublethal Hemorrhage

Abstract

The restoration of a normal circulating blood volume is the central problem in recovery from shock or hemorrhage. It has long been recognized that accessory factors may significantly affect the ability of the organism to restore a reduced blood volume; in many cases these factors may precipitate irreversible circulatory failure. The majority of experimental studies on shock and hemorrhage have utilized technics which produce death in untreated animals. Since the primary agent (hemorrhage, trauma, burning, or scalding) is sufficient in itself to produce death, the operation of accessory factors is difficult to evaluate. For this reason, we have adopted a standard hemorrhage of one-fourth the blood volume as the test procedure; recovery invariably occurs and restoration of blood volume follows a fairly uniform time course. The quantitative effect of accessory factors, whether favorable or unfavorable, may be estimated from alterations in the time curve of blood volume restoration. Experimental. Normal, unanesthetized adult dogs were used. Blood volume was calculated from simultaneous values for plasma volume and hematocrit cell volume (due to uncertainty concerning the reliability of cell volume determinations in shock and hemorrhage, the results are expressed directly in terms of plasma volume). Plasma volume was determined by the dye dilution method and hematocrit cell volume by centrifugation in Wintrobe tubes (1 hour at 3000 r.p.m.). Each animal was standardized in the following manner. The normal dye disappearance curve was established from duplicate tests 1 week apart. The standard plasma volume recovery curve was constructed from the average of 2 or more experiments in which plasma volume was determined prior to, and at intervals for 4 hours following a standard hemorrhage. Post-hemorrhage plasma volume values were calculated by reference of the determined dye concentration values to the normal dye disappearance curve.