Acute Kidney Injury (AKI) is a condition that occurs in critically ill patients when renal dysfunction prevents the elimination of waste products from the blood. When this happens, harmful levels of waste may build up, and the blood chemicals may get out of balance. Patients who suffer from AKI undergo hemodialysis, a form of continuous renal replacement therapy (CRRT), that can last up to 72 hours. During this process, the blood is purified through a filter, called the dialysis membrane, whose porous structure allows the removal of waste solutes. To verify the effectiveness of the therapy, the healthcare professionals should perform blood samplings from different sites in the extracorporeal circuit to analyse solute concentrations.