Low molecular weight hydroxyethyl starch 6% compared to albumin 4% during intentional hemodilution

Intentional normovolemic hemodilution was chosen as the model to compare a 6% low molecular weight hydroxyethyl starch (LMW HES) to 4% albumin. The study ran over the plasma exchange period for 24 h. Nine patients, scheduled for abdominal aortic surgery, were included in each group. After basal measurements, blood was withdrawn and simultaneously replaced by either 4% albumin (Group 1) or 6% LMW HES (Group 2) to achieve a final hematocrit of approximately 30%. Hemodynamic blood oxygen gas and hormonal plasma levels were determined before hemodilution then at 30 min, 1, 2, 3, and 24 h after the end of hemodilution. Basal value for total blood volume was 4377 +/- 162 ml in group 1 and 4138 +/- 315 ml in group 2. As in both groups the decrease in blood cell volume was exactly compensated by the increase in plasma volume, no significant change in total blood volume (respectively 4432 +/- 159 and 4305 +/- 267 ml) was observed. Throughout the study, in both groups, no significant change in mean arterial and right atrial pressures was observed. In group 2 (LMW HES), a significant increase of pulmonary capillary wedge pressure was noted 120 min after hemodilution. After hemodilution, despite a significant decrease in arterial oxygen O2 content, systemic oxygen transport did not significantly vary until 24 h in relation to the increased cardiac index. An increase in O2 extraction was observed after the exchange but no further increase was observed until the 24 h. No significant changes either in global O2 consumption or in lactate concentration were detected.(ABSTRACT TRUNCATED AT 250 WORDS)