Monitoring urine oxygen tension during acute change in cardiac output in dogs.

To evaluate whether renal blood flow (RBF) can be monitored during acute change in cardiac index, ureter urine oxygen tension (PuO2) and bladder urine oxygen tension (PbO2) were measured in six mongrel dogs. PuO2, cardiac index, and RBF increased after dobutamine infusion and decreased after propranolol infusion. PuO2 had an excellent correlation with RBF (r = 0.94) and a fair correlation with cardiac index (r = 0.50) and mean blood pressure (r = 0.56); RBF had a fair correlation with mean blood pressure (r = 0.52, P < 0.05) but was not related to cardiac index. With multiple-regression analysis, PuO2 was found to be the significant factor related to RBF. PbO2 had a good correlation with PuO2 (r = 0.94) at control levels. Furthermore, when two dogs were added to evaluate relationships among PbO2, PuO2, and RBF, PbO2 had an excellent correlation with PuO2 (r = 0.92) and RBF (r = 0.91). These data indicate that PuO2 is a more sensitive predictor of RBF than cardiac index and mean blood pressure and that PbO2 can be a noninvasive indicator reflecting RBF during acute circulatory change in dogs.