REAL-TIME OPTICAL MEASUREMENT OF CARDIORENAL TOXIN URIC ACID DURING HEMODIALYSIS

Objectives: Chronic kidney disease (CKD) patients are at higher cardiovascular risk than the general population. Vascular calcification (VC), one of the cardiovascular complications, is mediated by oxidative stress, inflammation, and accumulation of uremic toxins during CKD. Uric acid (UA) is a cardiorenal toxin that accumulates in the case of CKD. Therefore, effective removal of UA is crucial. The primary therapy for replacing kidney function and removing toxins from end-stage CKD patients is hemodialysis. Effective removal of toxins can be estimated by blood or dialysate lab analysis or optical monitoring. In this study, the authors tested a miniaturized optical sensor for monitoring UA levels and removal. Methods: Twenty-two patients were included, and concentration, removal ratio, and total removed amount of uric acid were observed during 88 hemodialysis sessions in Tallinn, Estonia. Four treatments for each patient were performed with different dialysis settings with two different dialysis modalities (HD and HDF) and various blood and dialysate flows and types of dialyzers according to predefined treatment settings. Optical multi-component monitor (MCM) sensor (Optofluid Technologies OÜ, Tallinn, Estonia), developed in the frame of European Commission project 767572 "Online Dialysis Sensor Phase2 (OLDIAS2), was connected with the dialysate outlet drain for uric acid measurements. As a reference, spent dialysate samples were collected and analyzed in the clinical chemistry laboratory. Results: The results (Mean±SD, Lab vs. Sensor) of the uric acid concentration 57.20±34.05 vs. 57.22±33.09 µmol/L, reduction ratio 68.72±10.91 vs. 67.89±12.48 %, and total removed amount 7.00±2.10 vs. 7.33±2.29 mmol did not differ significantly from the values obtained from the clinical laboratory (p