Acid-base and electrolyte status during normovolemic hemodilution with succinylated gelatin or HES-containing volume replacement solutions in rats.

Background: In the past, several studies have compared different colloidal replacement solutions, whereby the focus was usually on the respective colloid. We therefore systematically studied the influence of the carrier solution's composition of five approved colloidal volume replacement solutions (Gelafundin, Gelafusal, Geloplasma, Voluven and Volulyte) on acid-base as well as electrolyte status during and following acute severe normovolemic hemodilution. The solutions differed in the colloid used (succinylated gelatin vs. HES) and in the presence and concentration of metabolizable anions as well as in their electrolyte composition.

Methods: Anesthetized Wistar rats were subjected to a stepwise normovolemic hemodilution with one of the solutions until a final hematocrit of 10%. Subsequent to dilution (162 min), animals were observed for an additional period (150 min). During dilution and observation time blood gas analyses were performed eight times in total. Additionally, in the Voluven and Volulyte groups as well as in 6 Gelafundin animals, electrolyte concentrations, glucose, pH and succinylated gelatin were measured in urine and histopathological evaluation of the kidney was performed.

Results: All animals survived without any indications of injury. Although the employed solutions differed in their respective composition, comparable results in all plasma acid-base and electrolyte parameters studied were obtained. Plasma pH increased from approximately 7.28 to 7.39, the plasma K(+) concentration decreased from circa 5.20 mM to 4.80-3.90 mM and the plasma Cl(-) concentration rose from approximately 105 mM to 111-120 mM. Urinary analysis revealed increased excretion of K(+), H(+) and Cl(-).

Conclusions: The present data suggest that the carrier solution's composition with regard to metabolizable anions as well as K(+), Ca(2+) only has a minor impact on acid-base and electrolyte status after application of succinylated gelatin or HES-containing colloidal volume replacement solutions.