Validity of Blood Volume Determinations in Hemorrhagic Shock in Rats

Abstract

For the purpose of blood volume determination the mixing time and disappearance rate of R131IHSA and 51Cr-labelled erythrocytes was measured in rats under normal conditions and in hemorrhagic shock. Using a reservoir technique the mean arterial blood pressure of rats was reduced to 30 mm Hg over a period of 240 min (stage 1), 270 min (stage 2), and 300 min (stage 3). After this time the equilibration pattern and the blood volume were found to be markedly changed. The mixing time of both tracers was prolonged up to 6-fold in shock stage 1 and to 30-fold in shock stage 3. Whereas the disappearance rate of R131IHSA increased from 7 to 18%/h. Blood volume values measured with R131IHSA were always found to be higher than values determined with