Effect of blood returning from the extracorporeal circuit after HD on cerebral and hepatic oxygenation

Introduction: Large extracorporeal blood volume causes intradialytic hemodynamic instability. However, the impact of blood returning from the extracorporeal circuit on systemic tissue oxygenation after hemodialysis (HD) remains inadequately studied. Methods: This single-center prospective observational study included 33 patients who underwent HD and clinical data from 81 HD sessions. Post-HD, blood is pumped at a rate of 120 mL/min for 3 min as the extracorporeal circuit is rinsed. Cerebral and hepatic regional oxygenation saturation (rSO 2 ) levels were monitored from the end of HD to 5 min post-HD. Results: There were significant increases in cerebral and hepatic rSO 2 levels at 5 min post-HD compared with those post-HD (cerebral rSO 2 ; 52.6 ± 7.3 vs 54.2 ± 7.1, hepatic rSO 2 ; 63.0% ± 10.9% vs 68.8% ± 10.3%, p < 0.001, respectively). %Changes in hepatic rSO 2 at 5 min post-HD were significantly greater than those in cerebral rSO 2 (3.4% ± 5.7% vs 9.9% ± 6.7%, p < 0.001) and were independently and significantly associated with ultrafiltration rate (standardized coefficient: 0.217), mean blood pressure post-HD (−0.374), and oxygen saturation post-HD (0.258). Conclusions: We demonstrated that the impact of blood returning post-HD on changes in tissue oxygenation may have been greater in the liver than in the brain.