Neurological Impairment in Critically Ill Patients on Dialysis: Research Letter for the INCOGNITO-AKI Feasibility Study

BACKGROUND: Acute kidney injury (AKI) resulting in kidney replacement therapy is rising among critically ill adults. Long-term kidney replacement therapy and critical illness are independently linked to acute and prolonged cognitive impairment, and structural brain pathology. Poor regional cerebral oxygenation (rSO(2)) may be a contributing factor. OBJECTIVE: To assess the feasibility of testing the association between intradialytic rSO(2) and acute and long-term neurological outcomes. DESIGN: Longitudinal observational study. SETTING AND PARTICIPANTS: We enrolled patients initiating continuous kidney replacement therapy or intermittent hemodialysis in the Kingston Health Sciences Centre (KHSC) Intensive Care Unit (ICU). MEASUREMENTS AND METHODS: rSO(2) was monitored during the first 72 hours of continuous kidney replacement therapy or throughout each intermittent hemodialysis session. We measured acute neurological impairment by daily delirium screening and long-term neurocognitive outcomes using the Kinarm robot, Repeatable Battery for the Assessment of Neuropsychological Status, and brain magnetic resonance imaging. RESULTS: Of 484 ICU patients, 26 met the screening criteria. Two declined, and 13 met at least one exclusion criteria. Eleven patients were enrolled. Eight died in ICU, one died 2 months after discharge, and one declined follow-up. Data capture rates were high: rSO(2)/vitals (91.3%), and delirium screening and demographics (100%). Longitudinal testing was completed in 50% (1 of 2) of survivors. LIMITATIONS: Enrollment was low due to a variety of factors, limiting our ability to evaluate long-term outcomes. CONCLUSION: rSO(2) and delirium data collection is feasible in critically ill patients undergoing kidney replacement therapy; high mortality limits follow-up.