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

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.

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 (rSO₂) levels were monitored from the end of HD to 5 min post-HD.

There were significant increases in cerebral and hepatic rSO₂ levels at 5 min post-HD compared with those post-HD (cerebral rSO₂; 52.6 ± 7.3 vs 54.2 ± 7.1, hepatic rSO₂; 63.0% ± 10.9% vs 68.8% ± 10.3%, p < 0.001, respectively). %Changes in hepatic rSO₂ at 5 min post-HD were significantly greater than those in cerebral rSO₂ (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).

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.