| Abstract | The purpose of this study was to experimentally compare the hemodynamic variables, plasma colloidal and crystalloidal osmotic pressure (Pcop and Posm), and circulating blood volume (CBV), under normovolemic hemodilution in isoflurane-anesthetized dogs. We divided anesthetized dogs into two groups:a HES 70 group (hydroxyethyl starch, MW=70kDa, 6% in saline), and a HES 200 groups (hydroxyethyl starch, MW=200kDa, 6% in saline). Hemodilution was produced by exchanging blood (25ml/kg) with isovolemic artificial colloid of either HES 70 or HES 200. Measurements and sampling were taken before hemodilution, at the end of hemodilution, and 30, 60, 120, 180, 240, and 300 min after hemodilution. CBV was measured by pulse-dye densitometry (PDD) method. A significant increase in mean pulmonary arterial pressure (mPAP), cardiac index (CI), left ventricular stroke work index (LVSWI), and maximum rate of left ventricular pressure change (LV dp/dt max), and a significant decrease in systemic vascular resistance (SVR) values occurred after hemodilution in both groups. However, mAP, mPAP, pulmonary artery wedge pressure (PAWP) and LV dp/dt max values in group HES 70 decreased significantly over time compared with the pre-hemodilution condition. On the other hand, mPAP, CI, LVAWI and LV dp/dt max values in group HES 200 increased significantly. After hemodilution, CBV and Pcop increased significantly compared with the pre-hemodilution condition in both groups. In group HES 70, CBV and Pcop decreased from the pre-hemodilution condition over time, but not in group HES 200. Moreover, CBV and Pcop in group HES 200 significantly greater than those in group HES 70. On the other hand, Posm did not change significantly during any of the experimental periods compared to the pre-hemodilution condition in both groups. These results suggest that HES 200 may be more effective than HES 70 for the normovolemic hemodilution. This is due to an improvement and a maintainance in hemodynamic variables, CBV and Pcop. |
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