[Exact measurement of the volume effect of 6% hydoxyethyl starch 130/0.4 (Voluven) during acute preoperative normovolemic hemodilution]

Abstract

Background: What is the effect of preoperative acute normovolemic hemodilution (ANH) with 6% hydroxyethyl starch (HES) 130/0.4 (Voluven) on blood volume?

Methods: In 10 patients undergoing radical hysterectomy, ANH was performed to a hematocrit of 21% using 6% HES 130/0.4 (Voluven) whereby a replacement of blood with 115% of colloid was planned. Plasma volume (indocyanine green dilution technique) and hematocrit were determined before, 30 and 60 min after ANH. Red cell volume (labelling erythrocytes with fluorescein) was determined before and 30 min after ANH.

Results: After removal of 1,431+/-388 ml of blood and simultaneous replacement with 1,686+/-437 ml of colloid, blood volumes were 218+/-174 ml higher than before (at 105+/-4%). The volume effect was 98+/-12%, 30 min after ANH. Even 60 min after ANH, mean blood volumes were with 4,228+/-986 ml slightly higher than before ANH (102+/-5%). The hematocrit decreased disproportionally in relation to the residual intravascular volume. Consequently, estimating the volume effect from the changes in hematocrit led to an overestimation (about +30%).

Conclusion: Double label measurements of blood volume demonstrated that the volume effect of 6% HES 130/0.4 (Voluven) is about 100% in the course of ANH. The reason for the disproportionally large decrease in hematocrits could be the mobilization of a fraction of the plasma volume which was retained within the endothelial glycocalyx.