Evaluation of Cerebral Oxygenation in Patients Undergoing Long-Term Hemodialysis

Abstract

Background/Aims: Patients undergoing hemodialysis (HD) have higher occurrence rates of cerebral diseases, including uremic encephalopathy, cognitive impairment, dementia, and cerebrovascular disease, than the general population. During HD, ultrafiltration is performed to maintain an adequate fluid condition and is associated with subsequent blood volume (BV) reduction. We aimed to (1) monitor changes in cerebral oxygenation and BV reduction during HD, and (2) clarify the mechanism that influences cerebral oxygenation in HD patients. Methods: Eighteen HD patients and 12 healthy controls were recruited. Regional saturation of oxygen (rSO₂) was continuously monitored in the frontal cortex using INVOS 5100C before, during, and after HD, and in healthy controls. Relative change in BV (%ΔBV) was simultaneously monitored during HD using a BV monitor. Results: Before HD, patients had significantly lower rSO₂ values than controls (56.1 ± 1.4 vs. 70.4 ± 2.5%, p < 0.001). Although %ΔBV significantly decreased from 20 min to the end of HD (20 min: -3.3 ± 0.3%, p < 0.05; end of HD: -12.0 ± 1.0%, p < 0.01), changes in rSO₂ values during HD were not significant. No relationship existed between rSO₂ values and blood pressure levels, hemoglobin levels, oxygen pressure, HCO₃^-, oxygen saturation, and arterial O₂ content before and after HD. Furthermore, changes in rSO₂ were not correlated with changes in these parameters. Conclusion: rSO₂ values before HD were significantly lower in HD patients than in healthy controls. rSO₂ values were maintained during HD and were not influenced by BV reduction.