Renal tissue gas tensions during hemorrhagic shock

To evaluate the development of renal hypoxia during hemorrhagic shock, fourteen dogs were induced in this study. The animals were divided equally into a group in which mean arterial pressure (MAP) was kept at 50 mmHg (group 1), and into another where MAP was kept at 40 mmHg for 180 min (group 2). Renal tissue gas tensions were determined by a mass spectrometer. In the 50-mmHg group, renal tissue oxygen tension (PrO2) dropped for 15 min following hemorrhage, remained constant for 90 min, then fell further for 150 min before a plateau was established. In the 40-mmHg group, the PrO2 dropped for 90 min before reaching a plateau. The second PrO2 decline occurred at the same level in both the 50-mmHg group and the 40-mmHg group. The point at which the same PrO2 level occurred for each group suggests the cessation of oxygen consumption and the conditions of renal hypoxia. It is assumed that renal hypoxia occurs in 120 min at a MAP of 50-mmHg and in 60 min at a MAP of 40 mmHg.