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.

Table 2 Liver damage grading system (Mizuguchi et al[8], 2014, modified)

Parameters	Liver damagegrade A	Liver damagegrade B	Liver damagegrade C
Albumin (g/L)	> 3.5	3.5-3	< 3
Bilirubin (mg/dL)	< 2	2-3	< 3
PT (%)	> 80	50-80	< 50
Ascites	None	Small or controlled	Tense
IGCR15 (%)	< 15	15-40	> 40

PT: Prothrombin activity; ICG_R15: Indocyanine green retention ratio at 15 min.