Cerebral Perfusion During Inpatient Hemodialysis

Background: Hemodialysis (HD) has been associated with reductions in cerebral blood flow, with higher risks occurring at higher rates of fluid removal and greater reductions in blood pressure. In the setting of acute illness, patients may be particularly susceptible to HD-related hypoperfusion due to impaired cerebral autoregulation. We sought to examine if changes in regional cerebral oxygenation (rCO) are associated with ultrafiltration and blood pressure during inpatient HD. Methods: In a study of patients receiving inpatient HD for either end-stage kidney disease (ESKD) or acute kidney injury (AKI) at an academic university hospital between February 2024-April 2025. Patients were excluded if they had a recent COVID-19 infection, active delirium, or recent stroke. Throughout HD, participants had continuous cerebral oximetry monitoring using a near infrared spectroscopy probe placed across the prefrontal cortex (Artinis PortaLite MKII®) and central hematocrit and oxygen monitoring with dialysis monitors (CritLine-IV®). A subset of patients had cognitive testing (psychomotor vigilance test and trail making test) at the start, middle, and end of HD. Mixed effects models were used to examine the relationships between rCO, ultrafiltration, and blood pressure. Results: We analyzed data from 109 HD sessions across 93 participants (66.7% with ESKD and 33.3% with AKI), with mean(SD) age 60.8±13.5 years, 61.3% were men, 52% had diabetes, 43% had heart failure, and 9% had a history of stroke (with no residual deficit). Compared to the start of HD, the average reduction in rCO was 5.1±5.4%, and 15% of HD sessions had reductions in rCO≥10%. During HD, drops in rCO were correlated with the drops in systolic blood pressure (r=0.24, p<0.001) and mean arterial blood pressure (r=0.19, p<0.001). Each 0.1 ml/kg/h higher ultrafiltration rate was associated with a 3.0% reduction in rCO (95% CI: 0.7, 5.9) even with adjustment for AKI vs. ESKD, age, sex, and history of cardiovascular disease. Among 10 participants who had cognitive tests during HD, participants with reductions in rCO>5% (study mean) had worse performance on cognitive tests (3/4 participants) while those with rCO≤5% had similar or improved performance (6/6 participants). Conclusion: Intradialytic changes in cerebral perfusion could be a significant contributor to cognitive decline in patients receiving HD that warrants further investigation. Funding: NIDDK Support