Table 3.

Parameters involved in the pharmacodynamics model for 20 years old virtual patient.

Effect	Parameter	Symbol	Value	References	Note
Ventilation rate	First-order equilibrium rate constant	$k_{e,\mathrm{ }rd}$	7 × 10−4 s−1	Yassen et al., 2007	–
	Baseline effect	$E_{rd}^0$	20 L min−1		–
	Maximum effect	$E_{rd}^{\mathit{max}}$	12 × 0.91 L min−1		–
	Half maximal effective concentration	${EC}_{50,\mathrm{ }rd\mathrm{ }}$	1.14 ng ml−1		–
	Hill coefficient	${\gamma }_{rd}$	2.68		–
VAS pain score	First-order equilibrium rate constant	$k_{e,\mathrm{ }\mathit{VAS}}\mathrm{ }$**	2 × 10−3 s−1	Encinas et al., 2013	–
	Baseline effect	$E_{\mathit{VAS}}^0$	7	–	Assumed
	Maximum effect	$E_{\mathit{VAS}}^{\mathit{max}}$	7	–
	Half maximal effective concentration	${EC}_{50,\mathrm{ }\mathit{VAS}}$	1.35 ng ml−1	Sandler et al., 1992	Calculated based on fitting of the information in the literature.
	Hill coefficient	${\gamma }_{\mathit{VAS}}$	2.7

**This value is for analgesic effect.