The measurement of the liver function via the plasma disappearance rate of indocyanine
green (PDRICG) is a sensitive bed-side tool in critical care. Yet, recent evidence has questioned the value
of this method for hyperdynamic conditions. To evaluate this technique in different hemodynamic
settings, we analyzed the PDRICG and corresponding pharmacokinetic models after endotoxemia or
hemorrhagic shock in rats. Male anesthetized Sprague-Dawley rats underwent hemorrhage (mean
arterial pressure 35 ± 5 mmHg, 90 min) and 2 h of reperfusion, or lipopolysaccharide (LPS) induced
moderate or severe (1.0 vs. 10 mg/kg) endotoxemia for 6 h (each n = 6). Afterwards, PDRICG was
measured, and pharmacokinetic models were analyzed using nonlinear mixed effects modeling
(NONMEM®). Hemorrhagic shock resulted in a significant decrease of PDRICG, compared with sham
controls, and a corresponding attenuation of the calculated ICG clearance in 1- and 2-compartment
models, with the same log-likelihood. The induction of severe, but not moderate endotoxemia, led to
a significant reduction of PDRICG. The calculated ICG blood clearance was reduced in 1-compartment
models for both septic conditions. 2-compartment models performed with a significantly better log
likelihood, and the calculated clearance of ICG did not correspond well with PDRICG in both LPS
groups. 3-compartment models did not improve the log likelihood in any experiment. These results
demonstrate that PDRICG correlates well with ICG clearance in 1- and 2-compartment models after
hemorrhage. In endotoxemia, best described by a 2-compartment model, PDRICG may not truly
reflect the ICG clearance
