Elimination of indocyanine green in the perioperative evaluation of donor liver function

Current and Potential Applications for Indocyanine Green in Liver Transplantation

Indocyanine green (ICG) is a fluorescent dye taken up and almost exclusively cleared by the liver. Measurement of its clearance and visualization of its fluorescence make it suitable for a number of potential applications in liver transplantation including assessment of liver function and real-time assessment of arterial, venous, and biliary structures. ICG clearance can be used to assess donor graft quality before procurement and graft metabolic function before transplant using normothermic ex vivo machine perfusion. ICG clearance in the post-liver transplantation period is able to predict recipient outcomes with correlations to early allograft dysfunction and postoperative complications. After absorbing light in the near-infrared spectrum, ICG also emits fluorescence at 835 nm. This allows the assessment of vascular patency after reconstruction and patterns of liver perfusion in real time. ICG perfusion patterns after revascularization are also associated with posttransplant graft function and survival. ICG fluorescence cholangiography is routine in a number of centers and acts as an aid to identifying the optimal point of bile duct division during living donor liver transplantation to optimize safety for both donor and recipient. In summary, ICG is a versatile tool and has a number of useful applications in the liver transplantation journey including assessment of liver function, perfusion assessment, and cholangiography. Further research and clinical trials are required to validate and standardize its routine use in liver transplantation.

Fluorescence angiography-assisted debridement of critically perfused glabrous skin in degloving foot injuries: Two case reports

RATIONALE

Degloving foot injuries are challenging to treat and associated with life-long sequelae for patients. An appropriate debridement of ischemic soft tissues with maximal preservation of glabrous skin is key during the reconstruction of these injuries. Indocyanine green (ICG) fluorescence angiography is an established technique for the intraoperative evaluation of tissue perfusion.

PATIENT CONCERNS

Two patients sustained complex foot injuries in traffic accidents, including multiple fracture dislocations and extensive degloving of the plantar skin.

DIAGNOSIS

Clinical inspection revealed significant degloving of the glabrous skin in both patients.

INTERVENTIONS

After fracture fixation, ICG fluorescence angiography-assisted debridement with immediate latissimus dorsi free flap reconstruction was performed.

OUTCOMES

In both cases, this technique allowed a precise debridement with maximal preservation of the glabrous skin. The healing of the remaining glabrous skin was uneventful and the 6-month follow-up was characterized by stable soft tissues and satisfying ambulation.

LESSONS

ICG fluorescence angiography is a safe, user-friendly, and quick procedure with minimal risks, expanding the armamentarium of the reconstructive surgeon. It is highly useful for the debridement of extensive plantar degloving injuries and may also help to minimize the number of procedures and the risk of infection.

Role of Indocyanine Green in Predicting Post-Transarterial Chemoembolization Liver Failure in Hepatocellular Carcinoma

BACKGROUND/AIM

Post-Transarterial Chemoembolization (TACE) Liver Failure (LF) is common in patients with Hepatocellular Carcinoma (HCC). No definitive objective parameters predict its occurrence. We assessed the role of Indocyanine Green (ICG) in prediction of post-TACE LF.

METHODS

Consecutive HCC patients with Child A/B class, categorized as Barcelona Clinic Liver Cancer (BCLC) staging A/B, were included between August 2012 and July 2014. All underwent ICG dynamics: Plasma Disappearance Rate (PDR) was recorded on the day of TACE. Area Under Receiver Operator Characteristic Curve (AUROC) of ICG-PDR was compared with existing prognostic scores: Model for End Stage Liver Disease (MELD), MELD-Na and Child-Turcotte-Pugh (CTP) using Hanley and McNeil method.

RESULTS

A total of 43 patients, mean age (±sd) 55.1 ± 12.8 years were included; 35 (81.4%) patients were males. Post-TACE LF developed after 17 (28.8%) of 59 procedures. Patients with post-TACE LF had significantly elevated baseline bilirubin (P = 0.006), alkaline phosphatase (P = 0.040) and prolonged international normalized ratio (P = 0.004). The median prognostic scores were higher in patients with post-TACE LF (CTP 7 vs 6; P < 0.001 and MELD 10.5 vs 6.3; P = 0.005). There was no difference in the MELD-Na score. ICG-PDR values were lower in those patients who developed post-TACE LF (7.4%/min vs 10.6%/min; P = 0.008). AUROC for ICG-PDR was 0.72 and a cut-off value <9.25%/min predicted the development of post-TACE LF with a sensitivity, specificity, positive predictive value and negative predictive value of 64.7%, 61.9%, 40.7% and 81.2%, respectively. There were no differences in the AUROC between ICG-PDR and other prognostic markers (Hanley and McNeil, P: 0.244-0.900).

CONCLUSION

ICG-PDR performs similar to MELD, MELD-Na and CTP score for predicting development of post-TACE LF.

Reversal of fibrosis in patients with nonalcoholic steatohepatosis after gastric bypass surgery

Background

Roux-en-Y gastric bypass (RYGB) improves the pathophysiology that contributes to obesity-related nonalcoholic steatohepatitis (NASH).

Whether obesity-related fibrosis improves is unclear. We hypothesized that RYGB reverses NASH and fibrosis, and indocyanine green (ICG) clearance provides a sensitive measure for detecting asymptomatic fatty liver disease.

Methods

One hundred six obese adults scheduled for RYGB had preoperative liver function assessed using standard tests and ICG clearance and core liver biopsies obtained during RYGB. Once patients lost 60% of their preoperative weight or weight loss plateaued, liver function was reassessed. Repeat liver biopsies were obtained on patients with NASH at the time of RYGB.

Results

RYGB improved steatosis, lobular inflammation, hepatocyte ballooning and fibrosis. Serum albumin, AST, and ALT decreased the most in patients with NASH and NASH plus fibrosis. Twenty seven (26%) patients had normal baseline liver histology and 45 (43%) had NASH or NASH plus fibrosis. Nine of 13 patients with substantial fatty liver had normalized histology after weight loss, while severity of disease in the rest had stabilized or was reduced. Mean ICG clearance in patients with normal/mild fatty liver disease and those with histological fatty livers did not differ significantly.

Conclusions

RYGB surgery reverses NASH and liver fibrosis. Underlying mechanisms that facilitate improvement remain unclear.

Current use and perspective of indocyanine green clearance in liver diseases

Indocyanine green (ICG) is a water-soluble anionic compound that binds to plasma proteins after intravenous administration. It is selectively taken up at the first pass by hepatocytes and excreted unchanged into the bile. With the development of ICG elimination measurement by spectrophotometry, the ICG retention test has become a safe, rapid, reproducible, inexpensive and noninvasive tool for the assessment of liver function. Clinical evidence suggests that the ICG retention test can enable the establishment of tailored management strategies by providing prognostic information. In particular, this method has been evaluated as a prognostic marker in patients with advanced cirrhosis or awaiting liver transplantation. In addition, it is used as a marker of portal hypertension in cirrhotic patients, as a prognostic factor in intensive care units and for the assessment of liver function in patients undergoing liver surgery. Since recent technology enables ICG-PDR to be measured noninvasively at the bedside, this parameter is an attractive addition to liver function and regional haemodynamic monitoring. However, the current state-of-the-art as concerns this technology remains at a low level of evidence and thorough assessment is required.

Green light for liver function monitoring using indocyanine green? An overview of current clinical applications

The dye indocyanine green is familiar to anaesthetists, and has been studied for more than half a century for cardiovascular and hepatic function monitoring. It is still, however, not yet in routine clinical use in anaesthesia and critical care, at least in Europe. This review is intended to provide a critical analysis of the available evidence concerning the indications for clinical measurement of indocyanine green elimination as a diagnostic and prognostic tool in two areas: its role in peri-operative liver function monitoring during major hepatic resection and liver transplantation; and its role in critically ill patients on the intensive care unit, where it is used for prediction of mortality, and for assessment of the severity of acute liver failure or that of intra-abdominal hypertension. Although numerous studies have demonstrated that indocyanine green elimination measurements in these patient populations can provide diagnostic or prognostic information to the clinician, 'hard' evidence - i.e. high-quality prospective randomised controlled trials - is lacking, and therefore it is not yet time to give a green light for use of indocyanine green in routine clinical practice.

Early postoperative detection of tissue necrosis in amputation stumps with indocyanine green fluorescence angiography

OBJECTIVE

Amputations of the lower extremity due to irreversible ischemic tissue loss are performed as distally as possible. Therefore, oftentimes wound-healing disorders develop, requiring additional surgical treatment.

METHODS

The amputations stumps of 10 patients with irreversible ischemic tissue loss due to arteriosclerosis were investigated within 72 hours postoperatively with indocyanine green (ICG) fluorescence.

RESULTS

For 6 of the investigated stumps, no perfusion deficit could be seen through fluorescence angiography. All stumps displayed primary healing. In the fluorescence angiography of 3 amputations, stump perfusions deficits predicted later tissue necrosis and had to be amputated again in a second operation. One amputation wound showed a small ICG perfusion deficit that represented a blood clot.

CONCLUSION

Indocyanine green fluorescence angiography allows a perfusion analysis of amputation stumps and therefore a prediction of the expected tissue necrosis. This tool may allow reliable prediction of amputation level.

Pulse dye densitometry and indocyanine green plasma disappearance in ASA physical status I-II patients

BACKGROUND

Indocyanine green plasma disappearance rate (ICG-PDR) is used to evaluate hepatic function. Although hepatic failure is generally said to occur with an ICG-PDR <18%/min, ICG disappearance rate is poorly defined in the healthy population, and a clear cutoff value of ICG-PDR that discriminates between normal hepatic function and hepatic failure has not yet been described. We therefore defined the ICG disappearance rate in an otherwise healthy patient population. In addition, we evaluated the noninvasive measurement of ICG-PDR (transcutaneously by pulse dye densitometry [PDD] at the finger and the nose) and compared these with the simultaneously performed invasive measurements of ICG-PDR (in arterial blood).

METHODS

In patients without signs of liver disease, scheduled for elective nonhepatic surgery, 10 mg ICG was administered IV and ICG-PDR measured by PDD (DDG-2001, Nihon Kohden, Tokyo, Japan). In a subset of patients, arterial blood samples were gathered to compare PDD with invasive ICG measurements. Methods were compared using Bland-Altman analysis. The results of our study and reported studies on discriminative use of ICG-PDR in assessing liver failure were used to construct receiver operating characteristic curves.

RESULTS

Forty-one patients were studied: 33 using the finger probe and 8 using the nose probe. The mean +/- SD noninvasive ICG-PDR in this patient population is 23.1% +/- 7.9%/min (n = 41) with a range of 9.7% to 43.2%/min. Bias (+/-2 sd, limits of agreement) for ICG-PDR measured by PDD compared with those measured in arterial blood were 1.6%/min (-5.2% to 8.3%/min) for the finger probe and -6.0%/min (-15.5% to 3.4%/min) for the nose probe.

CONCLUSION

ICG-PDR values in a population without liver failure ranged well below 18%/min, cited as the cutoff value for hepatic failure. This cutoff value needs reconsideration. In addition, we conclude that the ICG concentration is adequately determined noninvasively by PDD.

Non-isotopic tyrosine kinetics using an alanyl-tyrosine dipeptide to assess graft function in liver transplant recipients - a pilot study

BACKGROUND

Although accurate assessment of liver function in liver transplant recipients is of crucial importance for optimal timing of the procedure and for determining graft viability, none of the many available methods has proven reliable in the clinical routine. Thus, a novel non-isotopic assay of tyrosine kinetics using the tyrosine-containing dipeptide L-alanyl-L-tyrosine (Ala-Tyr) was tested for its clinical feasibility in patients undergoing orthotopic liver transplantation (OLT).

METHODS

Plasma levels of tyrosine and clearance of tyrosine released after infusion of the dipetide Ala-Tyr were assessed before and one day after OLT in 10 liver transplant recipients with normal graft function, also in three organ donors and in three recipients showing poor graft function. Standard laboratory parameters (e.g. aminotransferases) and the plasma disappearance rate of indocyanine green were also measured.

RESULTS

Following uneventful OLT, tyrosine plasma levels (before 127 +/- 15 micromol/vs. post-OLT 52 +/- 6 micromol/l, P < 0.05) and kinetics (tyrosine clearance: before 206 +/- 77 ml/min vs. post-OLT 371 +/- 109 ml/min, P < 0.05) were normalized. In cases of severe graft dysfunction, tyrosine kinetics (tyrosine clearance: 238 +/- 61 ml/min) resembled the situation in end-stage liver disease, whereas no such correlation was seen with conventional markers of liver function. Organ preservation had only a minor impact on tyrosine kinetics (n.s.).

CONCLUSION

OLT rapidly normalizes both the plasma levels and the kinetics of tyrosine. Graft failure is associated with an immediate rise in plasma tyrosine levels and a delay in tyrosine elimination. Our results show that tyrosine clearance using the dipetide Ala-Tyr is a suitable non-isotopic, non-invasive indicator of graft viability in the early postoperative course following OLT.

Predicting immunosuppressant dosing in the early postoperative period with noninvasive indocyanine green elimination following orthotopic liver transplantation

Twenty adult patients undergoing orthotopic liver transplantation (OLT) were enrolled in this study, with the noninvasive indocyanine green plasma disappearance rate (ICG-PDR) measured both during and after OLT to assess the relationship between ICG-PDR and the ability of patients to achieve therapeutic postoperative tacrolimus immunosuppressant blood levels. Liver function was determined at both 2 and 18 hours post reperfusion with the ICG-PDR k value (1/min). Postoperative standard serum measures of liver function as well as liver biopsies were also collected and analyzed. The median ICG-PDR k value for the study group at 2 hours post reperfusion was 0.20 (0.16, 0.27), whereas at 18 hours post reperfusion, it was 0.22 (0.18, 0.35). The median change in the k value between the two ICG-PDR measurements was 0.05 (-0.02, 0.07) with P = 0.02. There was an interaction between the postoperative day 1 (18 hours post reperfusion) ICG-PDR k value and the linear increase in the tacrolimus blood level, such that the greater the k value was, the more gradual the observed rise was in tacrolimus over time [that is, the longer it took to achieve a therapeutic blood level (>12 ng/mL), P = 0.003]. Of the 16 patients that received tacrolimus, comparable dosing on a per kilogram body weight basis was observed. Also, no significant association between ICG-PDR k values and postoperative liver biopsy results was seen. This study demonstrates that the ICG-PDR measurement is a modality with the potential to assist in achieving adequate blood levels of tacrolimus following OLT.

Early detection of graft failure using the blood metabolic profile of a liver recipient

In this case report we describe the blood metabolic profile ("metabolomics") by nuclear magnetic resonance (NMR) spectroscopy and principle component analysis (PCA) from a patient who underwent two consecutive liver transplantations. The first graft from a living-related donor failed and was followed by a second successful transplant from a deceased donor. Using quantitative high-resolution H-NMR spectroscopy, 48 endogenous metabolites were analyzed in whole blood samples at baseline and different time points after each transplantation. From 48 analyzed metabolites, six metabolites were identified by PCA as metabolic markers consistent with a non-functional liver after first transplantation. Importantly, this distinctive metabolic profile was present as early as two hours after first transplant surgery when no other variable or conventional laboratory tests indicated poor graft function. This article reports the potential usefulness of quantitative H-NMR based metabolomics to diagnose early graft dysfunction in liver transplantation.

Early detection of graft failure using the blood metabolic profile of a liver recipient

In this case report we describe the blood metabolic profile ("metabolomics") by nuclear magnetic resonance (NMR) spectroscopy and principle component analysis (PCA) from a patient who underwent two consecutive liver transplantations. The first graft from a living-related donor failed and was followed by a second successful transplant from a deceased donor. Using quantitative high-resolution H-NMR spectroscopy, 48 endogenous metabolites were analyzed in whole blood samples at baseline and different time points after each transplantation. From 48 analyzed metabolites, six metabolites were identified by PCA as metabolic markers consistent with a non-functional liver after first transplantation. Importantly, this distinctive metabolic profile was present as early as two hours after first transplant surgery when no other variable or conventional laboratory tests indicated poor graft function. This article reports the potential usefulness of quantitative H-NMR based metabolomics to diagnose early graft dysfunction in liver transplantation.

Evaluation of skin perfusion by use of indocyanine green video angiography: Rational design and planning of trauma surgery

BACKGROUND

A very important aspect in the treatment of traumatic injuries is to determine the extent of skin involvement. Traditionally, this has involved clinical examinations, a more or less subjective technique. Therefore, various techniques, supplementing the clinical diagnosis, have been suggested, but none has yet achieved widespread clinical acceptance. Experiments have shown that the blood flow in injured tissue indicates the extent of tissue damage.

METHODS

The clinical and scientific impact of Indocyanine green (ICG) video angiographies was tested in 40 patients. All kinds of depth and all kinds of causes of injury were included and analyzed.

RESULTS

In all cases, it was possible to perform the ICG video angiography. Qualitative and quantitative measurements and observations correlated well with the extent and depth of the skin lesion, which was determined clinically (pre- and intraoperative assessment) and histologically (biopsies).

CONCLUSION

Based on our experiences, we think that the ICG video angiography seems to be a very sensible and user-friendly device to detect the vascular patency of the skin. Our results indicate that laser induced ICG fluorescence angiography is a practical, accurate, and effective adjunct to clinical methods for evaluating skin perfusion and thereby, helpful to design and plan surgery.

Accuracy of indocyanine green pulse spectrophotometry clearance test for liver function prediction in transplanted patients

AIM: To investigate whether the non-invasive real-time Indocynine green (ICG) clearance is a sensitive index of liver viability in patients before, during, and after liver transplantation.

METHODS: Thirteen patients were studied, two before, three during, and eight following liver transplantation, with two patients suffering acute rejection. The conventional invasive ICG clearance test and ICG pulse spectrophotometry non-invasive real-time ICG clearance test were performed simultaneously. Using linear regression analysis we tested the correlation between these two methods. The transplantation condition of these patients and serum total bilirubin (T. Bil), alanine aminotransferase (ALT), and platelet count were also evaluated.

RESULTS: The correlation between these two methods was excellent (r² = 0.977).

CONCLUSION: ICG pulse spectrophotometry clearance is a quick, non-invasive, and reliable liver function test in transplantation patients.