Detection of histamine-induced capillary protein leakage and hypovolaemia by determination of indocyanine green and glucose dilution method in dogs

Abstract

Objective: The plasma volume of histamine-induced protein capillary leakage may be over-estimated when this is determined using the indocyanine green (ICG) dilution method (Vd-ICG), since this dye binds to plasma proteins. The initial distribution volume of glucose (IDVG) has been shown to indicate the central extracellular fluid volume including plasma. Accordingly, the overestimation would be detected by a higher Vd-ICG/IDVG ratio. Our study was intended to examine whether the simultaneous measurement of these two variables can evaluate histamine-induced protein leakage and associated hypovolaemia. Design: Prospective animal study. Setting: Institutional animal research laboratory. Subjects: Twenty-four anaesthetized and ventilated mongrel dogs. Interventions: Anaesthetized animals were mechanically ventilated and received infusions of normal saline (n = 8), histamine 50 and μg/kg per h (n = 8), or histamine 100 μg/kg per h. The Vd-ICG and IDVG were calculated using a one-compartment model by simultaneous administration of ICG 0.5 mg/kg, and glucose 100 mg/kg followed by serial arterial blood sampling. Measurements and results: In both histamine groups, a significant elevation of haematocrit and a decrease of plasma albumin concentration were found (p < 0.05). Although the IDVG decreased following histamine administration (p < 0.05), the Vd-ICG remained unchanged. The Vd-ICG/IDVG ratio increased in a dose-dependent manner after histamine administration (p < 0.05), but remained unchanged following normal saline administration. Conclusion: The results suggest that the Vd-ICG/IDVG ratio and the IDVG are useful in evaluating the magnitude of the leakage and hypovolaemia.