Figure 8.

A Conventional breath test: Relation between the true value of the liver function parameter FHMC and the characteristic parameter DOB_max of DOB curves. DOB curves were simulated at various degrees of liver impairment by reducing the value of the model parameter k_L in steps of 10%. For each degree of liver function impairment, we used the 25 different parameters pairs k_+C, k_−C for systemic CO₂/bicarbonate kinetics obtained in the 25 investigated subjects. Note that for the liver-healthy ‘generic’ patient ( = 100% metabolization capacity) the variance of DOB_max is 8.1 thus being 25% of the mean (36.7). B 2DOB breath test: Relation between true and estimated values of the liver function parameter FHMC. Estimation of FHMC values was performed by fitting the compartment model to the 2-phasic DOB curve resulting from injection of ¹³C- bicarbonate followed by injection of ¹³C-methacetin (see Fig. 6).