Errors in estimating plasma volume by back-extrapolation for different clearance rates and different back-extrapolation times. In panel A, the ratio of the estimated PV to the true PV is shown for a range of ICG clearance in the simulations for two different back-extrapolation times (t = 0 and t = 1.08 min). Note that low values of α correspond to low clearance rates and, for values of α >100, there is nearly complete extraction of ICG by the liver. In panel B, the percentage error is the estimated PV is shown as a function of the back-extrapolation time used for simulations performed with clearance parameter α = 29 (for this value of α, the simulated plasma ICG profile is similar to the mean plasma ICG profile observed in the clinical study ). PV, plasma volume; ICG, indocyanine green.