[Influence of hypotensive anesthesia on the organ blood flow--comparison of trinitroglycerine and nicardipine].

Adult mongrel dogs under anesthesia with 50% N2O + 0.5% halothane were further subjected to hypotensive anesthesia. For hypotensive anesthesia, we used two different drugs: trinitroglycerine (TNG-group) and nicardipine (NIC-group). In each of these groups, we measured respiratory and circulatory parameters and organ blood flow. The parameters of organ blood flow measured were renal cortical blood flow (RCBF), renal medullarly blood flow (RMBF), liver blood flow (LBF) and muscle blood flow (MBF). At the same time, distribution of organ blood flow was also determined. In TNG-group, significant decreases were observed in CI, LV dp/dt max, MPAP and PCWP due to decrease in venous return. In NIC-group, CI and LV dp/dt max increased significantly. No significant changes were seen in PaO2 in both groups. During hypotensive anesthesia organ blood flow decreased in all sites in TNG-group. However, as to blood distribution rate in TNG-group, RCBF and RMBF increased significantly, while a decreasing tendency was seen in MBF. On the other hand, in NIC-group RCBF decreased significantly, while MBF increased significantly. In NIC-group, distribution rate of RCBF, RMBF and LBF decreased significantly, but MBF showed a tendency to increase. From these results, it was indicated that hypotensive anesthesia using NIC may be associated with increased bleeding from the operative field due to increase in MBF.