Comparison of invasive and noninvasive measurement of plasma disappearance rate of indocyanine green in patients undergoing liver transplantation: a prospective investigator-blinded study.

Plasma disappearance rate of indocyanine green (PDRICG) has been proposed for assessment of liver function in liver transplants donors and recipients, in patients with chronic liver failure, and as a prognostic factor in critically ill patients. The assessment of PDRICG using a newly developed noninvasive digital pulse densitometry method was simultaneously compared to invasive aortic fiber-optic method in patients undergoing orthotopic liver transplantation (OLT). Fourteen consecutive liver transplant candidates (11 male, 3 female) were prospectively enrolled into the study. A 4F aortic catheter with an integrated fiber-optic device and a thermistor was inserted via a femoral artery sheath for invasive aortic (INV) PDRICG assessment in all patients. The fiber-optic device was connected to a computer system (COLD-Z021, PULSION Medical Systems, Munich, Germany). A finger-piece sensor was used for non-invasive (NINV) pulse-densitometric PDRICG assessment. For the PDRICG assessment.5 mg/kg of ICG in cooled saline (10-15 mL) was injected through a central venous catheter. The assessments of PDRICG were performed after induction of anesthesia, after clamping of the hepatic artery, after clamping of the inferior vena cava, after reperfusion of the graft, and on the first postoperative day. During the PDRICG measurements, the investigators were blinded for the results of the noninvasive monitoring. Seventy-one pairs of measurements were performed successfully. PDRICG ranged from 0%/min to 43.8 %/min (11.6%/min +/- 9.6 %/min, mean +/- SD) for invasive and from 2.6%/min to 36.1 %/min (10%/min +/- 7.6 %/min, mean +/- SD) for noninvasive assessment method. The linear regression analysis yielded the equation: PDRICG(NINV) = 1.493 +/- 0.735 x PDRICG(INV), with a correlation coefficient of r = 0.93 (P <.0001). The analysis according to Bland and Altman showed a good agreement between the PDRICG(NINV) and PDRICG(INV) with a mean bias 1.5 +/- 3.8 for all measurements. In conclusion, according to these results, the noninvasive transcutaneous pulse-densitometric method correlates well with the invasive aortic fiber-optic method and thus can be used in patients undergoing liver transplantation.