Indocyanine green kinetics to assess liver function: Ready for a clinical dynamic assessment in major liver surgery?

Table 1 Quantitative indocyanine green kinetics variables (modified from Vos et al[6], 2014)

Variable	Denomination	Unit	Formula for calculation	Normal value
ICGPDR	ICG plasma disappearance rate	% per minute	Backward extrapolation of k, curve fitted as: CICG (t) = C0× e-k × t	> 18%-24% per minute
ICGR15	ICG retention ratio after 15 min	%	(CICG(15)/CICG(0)) × 100	< 10%
ICGt/2	ICG half life	min	(In2 × VD) CIICG	3-5
ClICG	ICG clearance	mL/min per kilogram	K × VD	6-12

e: Euler’s number (approximately 2.718); k: Fractional ICG concentration change per minute; V_D: ICG volume of distribution; t: Time; C_ICG (t): ICG concentration at time point t (min); Cl_ICG: ICG clearance (mL/min per kilogram); ICG: Indocyanine green.