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

Primary Nonfunction of the Liver Allograft

Severe allograft dysfunction, as opposed to the expected immediate function, following liver transplantation is a major complication, and the clinical manifestations of such that lead to either immediate retransplant or death are the catastrophic end of the spectrum. Primary nonfunction (PNF) has declined in incidence over the years, yet the impact on patient and healthcare teams, and the burden on the organ pool in case of the need for retransplant should not be underestimated. There is no universal test to define the diagnosis of PNF, and current criteria are based on various biochemical parameters surrogate of liver function; moreover, a disparity remains within different healthcare systems on selecting candidates eligible for urgent retransplantation. The impact on PNF from traditionally accepted risk factors has changed somewhat, mainly driven by the rising demand for organs, combined with the concerted approach by clinicians on the in-depth understanding of PNF, optimal graft recipient selection, mitigation of the clinical environment in which a marginal graft is reperfused, and postoperative management. Regardless of the mode, available data suggest machine perfusion strategies help reduce the incidence further but do not completely avert the risk of PNF. The mainstay of management relies on identifying severe allograft dysfunction at a very early stage and aggressive management, while excluding other identifiable causes that mimic severe organ dysfunction. This approach may help salvage some grafts by preventing total graft failure and also maintaining a patient in an optimal physiological state if retransplantation is considered the ultimate patient salvage strategy.

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.

Non-invasive tests for the prediction of primary hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common malignancies in the world and it is one of the main complications of cirrhosis and portal hypertension. Even in the presence of a well-established follow-up protocol for cirrhotic patients, to date poor data are available on predictive markers for primary HCC occurrence in the setting of compensated advanced chronic liver disease patients (cACLD). The gold standard method to evaluate the prognosis of patients with cACLD, beyond liver fibrosis assessed with histology, is the measurement of the hepatic venous pressure gradient (HVPG). An HVPG ≥10 mmHg has been related to an increased risk of HCC in cACLD patients. However, these methods are burdened by additional costs and risks for patients and are mostly available only in referral centers. In the last decade increasing research has focused on the evaluation of several, simple, non-invasive tests (NITs) as predictors of HCC development. We reviewed the currently available literature on biochemical and ultrasound-based scores developed for the non-invasive evaluation of liver fibrosis and portal hypertension in predicting primary HCC. We found that the most reliable methods to assess HCC risk were the liver stiffness measurement, the aspartate aminotransferase to platelet ratio index score and the fibrosis-4 index. Other promising NITs need further investigations and validation for different liver disease aetiologies.

Indocyanine green dye clearance test: early graft (dys)-function and long-term mortality after liver transplant. Should we continue to use it? An observational study

Early allograft dysfunction (EAD) can be a serious complication in the immediate postoperative period following liver transplantation. Our aim was to study the prognostic role of the indocyanine green plasma disappearance rate (ICG-PDR) in predicting early and late EAD and mortality at 3 and 12 months and 5 years after liver transplantation. ICG-PDR values were also assessed for association with the Donor Risk Index (DRI). 220 patients underwent orthotopic liver transplantation. In 77 patients, ICG-PDR was assessed on the 1st post-operative (PO) day. ICG, a water-soluble dye almost entirely excreted into the bile, was measured by spectrophotometry to evaluate graft (dys)-function. DRI was calculated in all patients. The primary study outcomes were the presence (or absence) of EAD after transplant and the results of mortality risk factor analysis. EAD occurred in 18 patients. 1st PO day ICG-PDR was significantly associated with EAD (p < 0.005). A threshold ICG-PDR value < 16%/min on the 1st PO day was also associated with patient probability to survive at 3 and 12 months and 5 years. The sensitivity and specificity of the AUC was good in predicting EAD, being 83% and 56%, respectively, for a 1st PO day ICG-PDR cut-off value < 16%/min. In this study, ICG-PDR on the 1st PO day following OLT can reliably predict EAD and survival at 3 and 12 months and 5 years. ICG-PDR should, therefore, be routinely performed on the 1st PO day following OLTx in all patients in light of its important prognostic role.

Risk factors, surgical complications and graft survival in liver transplant recipients with early allograft dysfunction

BACKGROUND

Early allograft dysfunction (EAD) is a severe complication after liver transplantation. The associated risk factors and complications have re-gained recent interest. This study investigated risk factors, survival and complications associated with EAD in a large liver transplant center in Latin America.

METHODS

Retrospective, unicenter, cohort, based on data from adult patients undergoing first deceased-donor liver transplant from January 2009 to December 2013. EAD was defined by one or more of the following: (i) bilirubin ≥10 mg/dL on postoperative day 7; (ii) international normalized ratio ≥1.6 on postoperative day 7, and (iii) alanine aminotransferase or aspartate aminotransferase >2000 IU/L within the first seven days after transplant.

RESULTS

A total of 602 patients were included; of these 34.2% developed EAD. Donor risk factors were male (P = 0.007), age between 50 and 59 years (P = 0.034), overweight (P = 0.028) or grade I obesity (P = 0.012), sodium >157 mmol/L (P = 0.002) and grade IV ischemia/reperfusion injury (P = 0.002). Cold ischemia time ≥10 h (P = 0.008) and warm ischemia time ≥40 min (P = 0.013) were the surgical factors. Male (P <0.001) was the only recipient protective factor. Compared with the non-EAD group, patients with EAD were submitted to more reoperations (24.3% vs. 13.4%, P = 0.001) and had higher graft loss rates (37.9% vs. 21.2%, P <0.001), with similar patient survival rates (P = 0.238).

CONCLUSIONS

EAD risk factors are related to donor, surgical procedure and recipient. Donor risk factors for EAD were male, age between 50 and 59 years, donor overweight or grade I obesity, sodium >157 mmol/L and grade IV ischemia/reperfusion injury. Cold ischemia time ≥10 h and warm ischemia time ≥40 min were the surgical risk factors. Male was the only recipient protective factor. Patients with EAD had higher reoperations and graft loss rates.

Predictive Value of Indocyanine Green Plasma Disappearance Rate on Liver Function and Complications After Liver Transplantation

BACKGROUND The aim of this study was to investigate the correlation between indocyanine green plasma disappearance rate (ICG-PDR) and allograft function as well as postoperative complications after liver transplantation. MATERIAL AND METHODS In this prospective study, 115 cases of adult liver transplantation performed from 1 June 2016 to 1 December 2016 were enrolled. These 115 patients were divided into a group of PDR <18%/min (50 cases) and a group of PDR ≥18%/min (65 cases). The rates of liver recovery, postoperative complications, and survival were compared between these 2 groups. RESULTS Among the total of 115 patients, 111 patients recovered well and were discharged, whereas 4 patients died during the first month after the operation. Between the 2 groups, significant differences were observed in terms of the model for end-stage liver disease (MELD) score, intraoperative bleeding volume, and the level of hemoglobin (Hb), pre-albumin (PA) and total bilirubin (TB) the first week after the operation. Overall, the incidence of hepatic arterial complications and pneumonia was much higher in the PDR<18%/min group (P<0.05). CONCLUSIONS The early postoperative value of ICG-PDR was closely related to graft function and could act as a good predictor for the incidence of postoperative arterial complications.

Early Measurement of Indocyanine Green Clearance Accurately Predicts Short-Term Outcomes After Liver Transplantation

BACKGROUND

There are no accurate tools to predict short-term mortality or the need for early retransplantation after liver transplantation (LT). A noninvasive measurement of indocyanine green clearance, the plasma disappearance rate (PDR), has been associated with initial graft function.

METHODS

We evaluated the ability of PDR to predict early mortality or retransplantation after LT. In this observational prospective study, 332 LT were analyzed. Donor, recipient, and intraoperative data were investigated. The ensuing score was prospectively evaluated in a validation cohort of 77 patients.

RESULTS

Thirty-three patients reached the main endpoint. By multivariate analysis, the only independent predictors of the endpoint were PDR (odds ratio [OR], 0.85; 95% confidence interval, 0.79-0.92) and international normalized ratio (OR, 1.45; 95% confidence interval, 1.17-1.82). A risk score weighted by the OR was built using cutoff values of 2.2 or greater for international normalized ratio (1 point) and less than 10%/min for PDR (2 points). Four categories (0 to 3) were possible. The risk of early death or retransplantation was associated with the score (0, 4.4%; 1, 6.5%; 2, 12%; and 3, 50%; χ for trend, P < 0.001). The score was also associated with duration of mechanical ventilation and intensive care unit stay. The score had a good diagnostic performance in the validation cohort (sensitivity, 60%; specificity, 95.5%; positive predictive value, 66.7%; negative predictive value, 94.1%).

CONCLUSIONS

A simple score obtained within the first day after LT predicts short-term survival and need for retransplantation and may prove useful when selecting diagnostic and therapeutic strategies.

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.

Postoperative Insulin-Like Growth Factor 1 Levels Reflect the Graft's Function and Predict Survival after Liver Transplantation

Background

The reduction of insulin-like growth factor 1 (IGF-1) plasma levels is associated with the degree of liver dysfunction and mortality in cirrhotic patients. However, little research is available on the recovery of the IGF-1 level and its prognostic role after liver transplantation (LT).

Methods

From April 2010 to May 2011, 31 patients were prospectively enrolled (25/6 M/F; mean age±SEM: 55.2±1.4 years), and IGF-1 serum levels were assessed preoperatively and at 15, 30, 90, 180 and 365 days after transplantation. The influence of the donor and recipient characteristics (age, use of extended criteria donor grafts, D-MELD and incidence of early allograft dysfunction) on hormonal concentration was analyzed. The prognostic role of IGF-1 level on patient survival and its correlation with routine liver function tests were also investigated.

Results

All patients showed low preoperative IGF-1 levels (mean±SEM: 29.5±2.1), and on postoperative day 15, a significant increase in the IGF-1 plasma level was observed (102.7±11.7 ng/ml; p<0.0001). During the first year after LT, the IGF-1 concentration remained significantly lower in recipients transplanted with older donors (>65 years) or extended criteria donor grafts. An inverse correlation between IGF-1 and bilirubin serum levels at day 15 (r = -0.3924, p = 0.0320) and 30 (r = -0.3894, p = 0.0368) was found. After multivariate analysis, early (within 15 days) IGF-1 normalization [Exp(b) = 3.913; p = 0.0484] was the only prognostic factor associated with an increased 3-year survival rate.

Conclusion

IGF-1 postoperative levels are correlated with the graft’s quality and reflect liver function. Early IGF-1 recovery is associated with a higher 3-year survival rate after LT.

The combination of MELD score and ICG liver testing predicts length of stay in the ICU and hospital mortality in liver transplant recipients

BACKGROUND

Early prediction of outcome would be useful for an optimal intensive care management of liver transplant recipients. Indocyanine green clearance can be measured non-invasively by pulse spectrophometry and is closely related to liver function.

METHODS

This study was undertaken to assess the predictive value of a combination of the model of end stage liver disease (MELD) score and early indocyanine plasma disappearance rates (ICG-PDR) for length of stay in the intensive care unit (ICU), length of stay in the hospital and hospital mortality in liver transplant recipients.

RESULTS

Fifty consecutive liver transplant recipients were included in this post Hoc single-center study. ICG-PDR was determined within 6 hours after ICU admission. Endpoints were length of stay in the ICU, length of hospital stay and hospital mortality. The combination of a high MELD score (MELD >25) and a low ICG-PDR clearance (ICG-PDR < 20%/minute) predicts a significant longer stay in the ICU (p = 0.004), a significant longer stay in the hospital (p < 0.001) and a hospital mortality of 40% vs. 0% (p = 0.003).

CONCLUSION

The combination of MELD scores and a singular ICG-PDR measurement in the early postoperative phase is an accurate predictor for outcome in liver transplant recipients. This easy-to-assess tool might be valuable for an optimal intensive care management of those patients.

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.

Primary graft dysfunction after liver transplantation

BACKGROUND

Primary graft dysfunction (PGD) causes complications in liver transplantation, which result in poor prognosis. Recipients who develop PGD usually experience a longer intensive care unit and hospital stay and have higher mortality and graft loss rates compared with those without graft dysfunction. However, because of the lack of universally accepted definition, early diagnosis of graft dysfunction is difficult. Additionally, numerous factors affect the allograft function after transplantation, making the prediction of PGD more difficult. The present review was to analyze the literature available on PGD and to propose a definition.

DATA SOURCE

A search of PubMed (up to the end of 2012) for English-language articles relevant to PGD was performed to clarify the characteristics, risk factors, and possible treatments or interventions for PGD.

RESULTS

There is no pathological diagnostic standard; many documented definitions of PGD are different. Many factors, such as donor status, procurement and transplant process and recipient illness may affect the function of graft, and ischemia-reperfusion injury is considered the direct cause. Potential managements which are helpful to improve graft function were investigated. Some of them are promising.

CONCLUSIONS

Our analyses suggested that the definition of PGD should include one or more of the following variables: (1) bilirubin ≥ 10 mg/dL on postoperative day 7; (2) international normalized ratio ≥ 1.6 on postoperative day 7; and (3) alanine aminotransferase or aspartate aminotransferase >2000 IU/L within 7 postoperative days. Reducing risk factors may decrease the incidence of PGD. A majority of the recipients could recover from PGD; however, when the graft progresses into primary non-function, the patients need to be treated with re-transplantation.

Early diagnosis of sepsis-related hepatic dysfunction and its prognostic impact on survival: a prospective study with the LiMAx test

INTRODUCTION

Liver dysfunction can derive from severe sepsis and might be associated with poor prognosis. However, diagnosis of septic liver dysfunction is challenging due to a lack of appropriate tests. Measurement of maximal liver function capacity (LiMAx test) has been successfully evaluated as a new diagnostic test in liver resection and transplantation. The aim of this study was to evaluate the LiMAx test during sepsis in comparison to biochemical tests and the indocyanin green test (ICG-PDR).

METHODS

We prospectively investigated 28 patients (8 female and 20 male, age range 35 to 80 years) suffering from sepsis on a surgical ICU. All patients received routine resuscitation from septic shock (surgery, fluids, catecholamines, antibiotic drugs). The first LiMAx test and ICG-PDR were carried out within the first 24 hours after onset of septic symptoms, followed by day 2, 5 and 10. Other biochemical parameters and scores determining the severity of illness were measured daily. Clinical outcome parameters were examined after 90 days or at the end of treatment. The population was divided into 2 groups (group A: non-survivors or ICU length of stay (ICU-LOS) >30 days versus group B: survivors and ICU-LOS <30 days) for analysis.

RESULTS

Epidemiological baseline characteristics of both groups were similar. Group A patients had significant lower LiMAx and ICG-PDR values than patients in group B. Determination of ICG-PDR by finger probe failed in 14.3% of tests due to insufficient peripheral pulses. Respiratory, renal and hepatic dysfunction (LiMAx and ICG-PDR) were associated with prolonged ICU-LOS. Only LiMAx <100 μg/kg/h and respiratory dysfunction were associated with increased mortality. For LiMAx <100 μg/kg/h receiver operating characteristic-analysis revealed a 100% sensitivity and 77% specificity for death.

CONCLUSIONS

Sepsis-related hepatic dysfunction can be diagnosed early and effectively by the LiMAx test. The extent of LiMAx impairment is predictive for patient morbidity and mortality. The sensitivity and specificity of the LiMAx test was superior to that of ICG-PDR regarding the prediction of mortality.