Changes in the initial distribution volume of glucose and plasma volume following volume challenge in dogs.

Objective: This study aimed to test the hypothesis that the initial distribution volume of glucose (IDVG) is correlated with plasma volume determined by indocyanine green (ICG) following colloidal fluid challenges. The IDVG was also compared with cardiac output (CO) as measured by the conventional thermodilution method.

Design and setting: The study was prospective and was conducted in the animal laboratory, University of Hirosaki School of Medicine, after approval of the institutional animal experiment committee.

Participants: Thirteen mongrel dogs of either sex, weighing 9.0-14.5 kg, were the subjects of the study.

Interventions: They were anesthetized with pentobarbital and paralyzed with pancuronium. 30 ml x kg(-1) of 3% dextran in lactated Ringer's solution was given twice to induce a hypervolemic state.

Measurements and results: In each stage of the fluid loading, the IDVG, plasma volume and CO were measured simultaneously. The IDVG was measured following an injection of glucose (100 mg x kg(-1)) by repeated determinations of plasma glucose (3-7 min) with a one-compartment model, and plasma volume was assessed similarly following ICG (0.5 mg x kg(-1) injection. A closer correlation was observed between the IDVG and plasma volume (r = 0.79, p < 0.001) than between the IDVG and CO (r = 0.48, p < 0.01).

Conclusion: The IDVG correlates with plasma volume following volume challenge in dogs. CO did not show a consistent change following volume challenge. The IDVG may have the potential as an indicator to presume the fluid volume in the body, even though the IDVG cannot be used directly to estimate plasma volume.