Bilirubin kinetic modeling for quantification of extracorporeal liver support

Abstract

Background/aim: To provide a measure of treatment dose for extracorporeal liver support (ELS).

Methods: The kinetics of conjugated bilirubin were described by a two-compartment model (Vc, Vp) with central elimination (K) and constant generation rate (G). The transfer of solute between compartments was modeled by intercompartmental clearance (Kpc). The central compartment (Vc) was assumed as a constant fraction of total volume (Vc = 0.3*Vt).

Results: Eight patients were studied during 35 treatments lasting 6 h each. The average K, Vt, Kpc, G, and mass of conjugated bilirubin removed were 18.6 +/- 3.9 ml/min, 9.1 +/- 3.8 liters, 103 +/- 108 ml/min, 0.33 +/- 0.15 mg/min, and 641 +/- 275 mg, respectively. The reduction ratio (48 +/- 10%) measured as the change in post- to pre-treatment concentrations underestimated the modeled fraction of bilirubin mass removed (54 +/- 13%) essentially because of significant conjugated bilirubin appearance during treatments.

Conclusions: Kinetic analysis provides an improved measure of treatment dose as generation, distribution, and elimination of conjugated bilirubin are jointly considered.