Abstract
This investigation evaluated the systemic hemodynamics and splanchnic blood flow as compared with amrinone or sodium nitroprusside (SNP) during isovolemic hemodilution in anesthetized dogs. Twenty adult male mongrel dogs weighing from 12 to 21 kg were used in this investigation. We divided the animals randomly into 2 groups : an amrinone (A) group, and an SNP (S) group. The animals were anesthetized with a 1MAC isoflurane concentration in 60% nitrous oxide. Splanchnic blood flow was determined by the hydrogen gas clearance method. A laparotomy was performed so the hydrogen gas clearance electrodes could be inserted into the liver ( LBF), renal cortex (RCBF), renal medulla (RMBF) and pancreas (PBF) . Subsequentry, hemodilution was carried out by exchanging blood (20 ml/kg) with isovolemic hydroxyethyl starch (6% in saline, MW=200 kDa) . Either intravenous infusion of amrinone or SNP to decrease the mean arterial pressure (mAP) to 85% (HP-1) and 70% (HP-2) of the baseline values performed a hypotension in the hemodiluted animals. In both groups, the cardiac index (CI) increased significantly during the hypotensive period compared with baseline values. In the A group, the maximum rates of change of left ventricular pressure (LV dp/dt max) increased during both HP-1 and HP-2. In the S group, LV dp/dt max increased significantly during HP-1, but not during HP-2. In both groups, RCBF increased during HP-1; moreover, RMBF increased during both HP-1 and HP-2. In both groups, LBF and PBF did not differ as compared with the baseline values. These results indicate that amrinone can be a useful hypotensive agent during isovolemic hemodilution.
