Regional and systemic hemodynamics during hemodilution with isovolemic hydroxyethyl starch solution alone and in combination with sodium nitroprusside- or isoflurane-induced controlled hypotension in isoflurane-anesthetized dogs

Objective: The aim of the present study was to assess systemic and splanchn ic hemodynamics during isovolemic hemodilution and during controlled hypote nsion induced by sodium nitroprusside (SNP) or isoflurane (ISO) in ISO-anes thetized dogs. Methods: Hemodilution was performed by exchanging blood (20 mL/kg) with iso volemic hydroxyethyl starch solution (6% in saline, molecular weight 70 kd) , Hypotension was induced for 90 minutes, with a mean arterial pressure of 70 mm Hg. Results: Hemodilution combined with SNP-induced hypotension produced an inc reased cardiac index (CI) and a maximal left ventricular pressure change (L V dp/dt(max)) compared with prehemodilution values. ISO-induced hypotension produced a decreased CI, During the hypotensive period, CI and LV dp/dt(ma x) in the SNP group were significantly greater than in the LSO group. In th e SNP group, the changes from prehemodilution values in renal cortical and medullary blood flow (RCBF and RMBF) were not significant during conditions of hemodilution and induced hypotension, but Liver and pancreatic blood fl ow (LBF and PBF) were significantly decreased (P < 0.05). However, blood Ho w through all splanchnic organs decreased significantly in the ISO group (P < 0.05). In the hypotensive state, LBF, RCBF, and RMBF were significantly greater in the SNP group than in the ISO group (P < 0.05). Conclusions: Results of the present paper suggest that with respect to spla nchnic hemodynamic variables, SNP is preferable to ISO as a hypotensive age nt during hemodilution.