MEASUREMENTS OF EXTRACELLULAR FLUID VOLUME IN HIGHLY PERFUSED ORGANS AND LUNG WATER IN HYPOVOLEMIC AND HYPERVOLEMIC DOGS

The purpose of this study was to identify whether the central extracel lular fluid volume status following hypo- and hypervolaemia can be mea sured by the initial distribution volume of glucose or by the extravas cular lung water. These two estimates were compared with the initial d istribution volume of sucrose which has been used as an indicator for the measurement of the extracellular fluid volume. The above three est imates were determined by the administration of glucose, chilled salin e and sucrose solutions, before and after haemorrhage (30 mt kg(-1)), and subsequent fluid load (lactated Ringer's solution 90 mt kg(-1)). T he distribution volumes of glucose and sucrose decreased after haemorr hage and increased after fluid load compared with normovolaemic values , and a linear correlation was obtained between these two distribution volumes (r=0.93, P<0.001, n=36). However, the extravascular lung wate r remained statistically unchanged throughout the procedure, despite a weak linear correlation with the sucrose distribution volume (r=0.38, n=33, P<0.05). These results indicate that the initial distribution v olume of glucose is more useful as an indicator of the central extrace llular fluid volume status than the extravascular lung water.