A modeling study of bilirubin kinetics during Molecular Adsorbent Recirculating System sessions

This work presents a quantitative description, by means of a mathematical model, of bilirubin removal during Molecular Adsorbent Recirculating System sessions. The model includes four compartments: two for the patient, and two for the albumin circuit. Equations in each compartment express mass preservation, mass exchange between compartments, and bilirubin-albumin binding kinetics. Model development and validation are based on in vivo data of bilirubin concentration acquired in eight sessions at different times during the session. The accuracy of the model in reproducing real data is high (error in blood = -0.3 +/- 0.93 mg/dL), if three parameters, representing the depurative efficacy of the system (the dialysance of the blood filter and the initial and final clearance of the depurative elements in the albumin circuit), are estimated on each single session. However, model accuracy is only slightly deteriorated (error in blood = -0.4 +/- 0.99 mg/dL) if a single set of parameters (fixing the three parameters at their mean values) is adopted. These results suggest that the model may be used a priori (i.e., using a single set of parameters) to achieve a satisfactory prediction of the overall bilirubin removal, as well as a posteriori for the estimation of device parameters. The latter use may allow the investigation of the dependence of these parameters on the operative and clinical conditions, in the effort to arrive at a rationalization and optimization of the treatment.