Limitations of use of the noninvasive clearance of indocyanine green as a prognostic indicator of graft function in liver transplantation

Abstract

Aim: To assess the prognostic value of noninvasive indocyanine green (ICG) clearance (ICG-pulse-densitometric method [PDR]) for the outcome of liver grafts after transplantation.

Methods: ICG-PDR, hepatic artery resistance index, cardiac output, transaminases, prothrombin time, bilirubin, albumin, hematocrit at 48 to 72 hours after transplantation were analyzed with reference to outcome among 59 liver graft recipients.

Results: Two grafts were lost at 10 and 88 days during the initial hospitalization. These two patients only differed from the other recipients in the need for packing (1/2 versus 3/57) and degree of hypoproteinemia (46 ± 0 versus 51 ± 7.8 g/L), whereas they had similar ICG-PDR values (16.7%/min and 21.8%/min versus 17.3%/min ± 7.2%/min). Seven patients showed an ICG-PDR ≤ 8.8%/min, a previously identified cutoff for early postoperative complications. These patients versus the other 52 significantly differed in prothrombin index (47.9% ± 15.9% versus 64.3% ± 11.7%, P = .001) and bilirubin (8.3 ± 3.2 versus 3.3 ± 2.9 mg/dL, P = .0001). Early postoperative complications--primary graft nonfunction, hepatic artery thrombosis, or septic shock--responsible for an ICG-PDR ≤ 8.8%/min were observed in 2/7 patients. Interestingly, six cases developed an early (range: 3-15 days) rejection episode. In all the cases rejection suspected by analytical abnormalities was confirmed by liver biopsy. Among the overall series of patients, ICG-PDR significantly correlated with serum albumin (r = 0.345; P = .007), bilirubin (r = -0.514; P = .0001), and hematocrit (r = 0.462; P = .0001) but not with transaminases, prothrombin index, cardiac output, or hepatic artery resistance index. Actuarial 72-month probability of graft survival was 75%. Overall, 14 grafts were lost over a median follow-up of 78 months (range 1-99 m). There were no significant differences among early ICG-PDR values among grafts lost vs retained upon follow-up.

Conclusion: ICG-PDR measured once early after liver transplantation did not offer relevant information to predict individual patient outcomes in the immediate postoperative phase. This lack of prognostic value may have been due to the multiple confounding factors involved in ICG metabolism after liver transplantation.