Does indocyanine green accurately measure plasma volume independently of its disappearance rate from plasma in critically ill patients?

Abstract

To determine whether plasma volume determined by the indocyanine green (ICG) dilution method (PV-ICG) is equally accurate independently of its disappearance rate from plasma in the critically ill. Retrospective clinical investigation. Intensive care unit of a university teaching hospital. 192 adult patients were initially enrolled. The PV-ICG and the initial distribution volume of glucose (IDVG) were calculated utilizing a one-compartment model by simultaneous administration of ICG 25 mg and glucose 5 g on the first day of measurement in each patient. Twenty-one patients were excluded from the study because of a higher PV-ICG/IDVG ratio (> 0.45) indicating apparent overestimation of the PV-ICG associated with the generalized protein capillary leakage. The remaining 171 patients were divided into four groups according to the magnitude of their disappearance rate of ICG from plasma (Ke-ICG). Convergence was assumed consistently in each ICG or glucose decay curve, even in the lower Ke-ICG less than 0.10/min. The relationship between the two volumes was not statistically different among groups. The results suggest that the measurement of the PV-ICG can be equally accurate independently of its disappearance rate from plasma unless there is generalized protein capillary leakage.