Cerebral Perfusion in Hemodialysis Patients: A Feasibility Study

Background: Patients on hemodialysis (HD) are known to exhibit low values of regional cerebral oxygenation (rSO2) and impaired cognitive functioning. The etiology of both is currently unknown. Objective: To determine the feasibility of serially monitoring rSO2 in patients initiating HD. In addition, we sought to investigate how rSO2 is related to hemodynamic and dialysis parameters. Design: Prospective observational study. Setting: Single-center tertiary academic teaching hospital in Ontario, Canada. Participants: Six patients initiating HD were enrolled in the study. Methods: Feasibility was defined as successful study enrollment (>1 patient/month), successful consent rate (>70%), high data capture rates (>90%), and assessment tolerability. Regional cerebral oxygenation monitoring was performed 1 time/wk for the first year of dialysis. A neuropsychological battery was performed 3 times during the study: before dialysis initiation, 3 months, and 1 year after dialysis initiation. The neuropsychological battery included a traditional screening tool: the Repeatable Battery for the Assessment of Neuropsychological Status, and a robot-based assessment: Kinarm. Results: Our overall consent rate was 33%, and our enrollment rate was 0.4 patients/mo. In total 243 rSO2 sessions were recorded, with a data capture rate of 91.4% (222/243) across the 6 patients. Throughout the study, no adverse interactions were reported. Correlations between rSO2 with hemodynamic and dialysis parameters showed individual patient variability. However, at the individual level, all patients demonstrated positive correlations between mean arterial pressure and rSO2. Patients who had more than 3 liters of fluid showed significant negative correlations with rSO2. Less cognitive impairment was detected after initiating dialysis. Limitation: This small cohort limits conclusions that can be made between rSO2 and hemodynamic and dialysis parameters. Conclusions: Prospectively monitoring rSO2 in patients was unfeasible in a single dialysis unit, due to low consent and enrollment rates. However, rSO2 monitoring may provide unique insights into the effects of HD on cerebral oxygenation that should be further investigated.