Plasma disappearance rate of indocyanine green: a tool to evaluate early graft outcome after liver transplantation

A bibliometric analysis of indocyanine green (ICG) in hepatobiliary surgery from 2008 to 2021

Hundreds of scientific documents have reported on the application of indocyanine green (ICG) in hepatobiliary surgery in the past 13 years, but few bibliometric studies have been conducted. This study aimed to identify the situations of authors, countries/regions, institutions, journals, and hot topics in this field. The overall status and prospects of the current research in this field can be elucidated by bibliometric analysis. Publications from 2008 to 2021 were retrieved from the Web of Science (WoS) Core Collection. The search terms included "liver," "hepatic," "gallbladder," "bile duct," "surgery," "hepatectomy," "ICG," "indocyanine green," and related synonyms. The full records of the search results were exported in text, and the cooperation network and hot topics were evaluated and visualized using CiteSpace software. The number of publications increased between 2008 and 2021. A total of 1527 publications were included in the results, and the frequency of citations was 30,742. The largest proportion of the publications emanated from Japan, and the majority of the papers were published by Kokudo. Tian Jie contributed the largest number of papers in China. Research was relatively concentrated among one country/region. The latest hotspots, "preservation" and "resistance", frequently occurred. Cooperation between authors, countries, and institutions needs to be strengthened for high-quality research. Recent studies have focused on hepatectomy, bile duct resection, liver transplantation, and tumors in this field. Future research may focus on other aspects, such as liver preservation and resistance.

Indocyanine green clearance tests to assess liver transplantation outcomes: a systematic review

BACKGROUND

Liver transplantation (LT) is the gold standard for end-stage liver disease, yet postoperative complications challenge patients and physicians. Indocyanine green (ICG) clearance, a quantitative dynamic test of liver function, is a rapid, reproducible, and reliable test of liver function. This study aimed to systematically review and summarize current literature analyzing the association between ICG tests and post-LT outcomes.

METHODS

This systematic review was conducted according to PRISMA guidelines. MEDLINE and Cochrane Library, as main databases, and other sources were searched until August 2022 to identify articles reporting the prognostic value of postoperative ICG tests associated with outcomes of adult LT recipients.Risk of bias of included articles was assessed using Quality In Prognosis Studies tool. Methodological quality varied from low to high across risk of bias domains.

RESULTS

Six studies conducted between 1994 and 2018 in Europe, America, and Asia were included. The study population ranged from 50 to 332 participants. ICG clearance on the first postoperative day was associated with early allograft dysfunction, graft loss, 1-month and 3-month patient survival probability, prolonged ICU, and hospital stay. The dichotomized ICG plasma disappearance rate (PDR) provided a strong association with medium-term and long-term outcomes: PDR less than 10%/min with 1-month mortality or re-transplantation (odds ratio: 7.89, 95% CI 3.59-17.34, P <0.001) and PDR less than 16.0%/min with 3-month patient survival probability (hazard ratio: 13.90, 95% CI 4.67-41.35, P <0.01). The preoperative model for end-stage liver disease and body mass index were independent prognostic factors for early allograft dysfunction, early complications, and prolonged ICU stay; post-LT prothrombin time and INR were independently associated with graft loss and bilirubin with a prolonged hospital stay.

CONCLUSION

This review shows that ICG clearance tests are associated with graft function recovery, suggesting that a potential prognostic role of ICG test, as an aid in predicting the post-LT course, could be considered.

Indocyanine green clearance test as a predictor of linezolid overexposure in septic patients

OBJECTIVES

Hepatic impairment increases the risk of drug overexposure in septic patients. However, there is a lack of effective indicators to predict overexposure risk. The indocyanine green (ICG) clearance test is a helpful method for dynamically assessing hepatic function and perfusion. This study aimed to investigate whether the ICG test could serve as a potential predictor of linezolid trough concentration (Cmin) and to compare its efficacy with that of conventional liver function markers.

METHODS

A total of 35 consecutive septic patients treated with linezolid were grouped into either linezolid Cmin of ≤7 µg/mL or >7 µg/mL. Correlations between linezolid Cmin and ICG-PDR (plasma disappearance rate), ICG-R15 (retention ratio after 15 min) and other traditional indicators were analysed by Spearman's rank test. A multivariable regression model was employed to discern factors contributing independently to overexposure.

RESULTS

Statistical differences were observed between groups for APACHE II score (P = 0.031), SOFA score (P = 0.018), creatinine clearance (CLCr) (P = 0.003), thrombocytes (P = 0.039), lactate (P = 0.003), ICG-PDR (P < 0.001) and ICG-R15 (P < 0.001). Moreover, linezolid Cmin was correlated with ICG-PDR (ρ = -0.628, P < 0.001), ICG-R15 (ρ = 0.676, P < 0.001) and CLCr (ρ = -0.503, P = 0.002). ICG-PDR was identified as an independent predictor of linezolid overexposure, with an optimal cut-off value of 17.70%/min (93.3% sensitivity, 85.0% specificity; P < 0.001).

CONCLUSIONS

This pilot clinical trial represents the first investigation of potential of the ICG test to predict linezolid overexposure in septic patients.

[Indocyanine green in liver transplantation]

The purpose of this study was to evaluate the first own experience of using indocyanine green (ICG) in liver transplantation compared to literature data and to determine its potential for clinical practice. Liver transplantation is an effective option for patients with end-stage disease, but this procedure is associated with many problems such as graft rejection, graft dysfunction, surgical risk and postoperative management. Modern methods for assessing graft function have their limitations, so a more efficient method is needed. According to this review, ICG fluorescence is valuable for effective intraoperative blood flow control, assessment of graft function, intraoperative and postoperative monitoring of clinical status. ICG fluorescence can also predict clinical status of patients at all stages of liver transplantation. Routine ICG fluorescence method is advisable in liver transplantation to improve outcomes and optimize treatment process.

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.

Association between the donor to recipient ICG-PDR variation rate and the functional recovery of the graft after orthotopic liver transplantation: A case series

Background

Despite current advances in liver transplant surgery, post-operative early allograft dysfunction still complicates the patient prognosis and graft survival. The transition from the donor has not been yet fully understood, and no study quantifies if and how the liver function changes through its transfer to the recipient. The indocyanine green dye plasma disappearance rate (ICG-PDR) is a simple validated tool of liver function assessment. The variation rate between the donor and recipient ICG-PDR still needs to be investigated.

Materials and methods

Single-center retrospective study. ICG-PDR determinations were performed before graft retrieval (T1) and 24 hours after transplant (T2). The ICG-PDR relative variation rate between T1 and T2 was calculated to assess the graft function and suffering/recovering. Matched data were compared with the MEAF model of graft dysfunction.

Objective

To investigate whether the variation rate between the donor ICG-PDR value and the recipient ICG-PDR measurement on first postoperative day (POD₁) can be associated with the MEAF score.

Results

36 ICG-PDR measurements between 18 donors and 18 graft recipients were performed. The mean donor ICG-PDR was 22.64 (SD 6.35), and the mean receiver’s ICG-PDR on 1st POD was 17.68 (SD 6.60), with a mean MEAF value of 4.51 (SD 1.23). Pearson’s test stressed a good, linear inverse correlation between the ICG-PDR relative variation and the MEAF values, correlation coefficient -0.580 (p = 0.012).

Conclusion

The direct correlation between the donor to recipient ICG-PDR variation rate and MEAF was found. Measurements at T1 and T2 showed an up- or downtrend of the graft performance that reflect the MEAF values.

Automatic Liver Viability Scoring with Deep Learning and Hyperspectral Imaging

Hyperspectral imaging (HSI) is a non-invasive imaging modality already applied to evaluate hepatic oxygenation and to discriminate different models of hepatic ischemia. Nevertheless, the ability of HSI to detect and predict the reperfusion damage intraoperatively was not yet assessed. Hypoxia caused by hepatic artery occlusion (HAO) in the liver brings about dreadful vascular complications known as ischemia-reperfusion injury (IRI). Here, we show the evaluation of liver viability in an HAO model with an artificial intelligence-based analysis of HSI. We have combined the potential of HSI to extract quantitative optical tissue properties with a deep learning-based model using convolutional neural networks. The artificial intelligence (AI) score of liver viability showed a significant correlation with capillary lactate from the liver surface (r = −0.78, p = 0.0320) and Suzuki’s score (r = −0.96, p = 0.0012). CD31 immunostaining confirmed the microvascular damage accordingly with the AI score. Our results ultimately show the potential of an HSI-AI-based analysis to predict liver viability, thereby prompting for intraoperative tool development to explore its application in a clinical setting.

Gamma Radiation-Induced Rib Necrosis and Stereotactic Radiosurgery Failure

Stereotactic radiosurgery, or SRS, uses focused beams of gamma radiation targeted to specific areas of the body and has been used for multiple forms of non-small cell lung cancer. In this article, the authors describe two incidental cases of osteonecrosis in patients who had previously undergone stereotactic radiosurgery with recurrence of tumor. While this is a known side effect of traditional radiation therapy, it has not been described in the context of stereotactic radiosurgery. Further, these lesions were immediately deep to a rib, which may have shielded the lesion, and led to SRS failure. Osteonecrosis of the rib is a rare clinical entity but has been found to occur with glucocorticoid use, bisphosphonates, radiation therapy, and radiofrequency ablation. In the authors' review of the literature on SRS for lung cancer and intrathoracic pathology, rib osteonecrosis was not described and has not been mentioned as a possible side effect. Patients who have undergone thoracic stereotactic radiotherapy may develop side effects of traditional radiotherapy. We identified two patients who developed rib osteonecrosis though that has not been previously described as an adverse effect of stereotactic radiotherapy. The patients described in this case did not have any radiographic evidence of disease on imaging, suggesting that further research is warranted on the diagnosis and management of this rare disease entity.

Indocyanine Green Fluorescence Imaging to Predict Graft Survival After Orthotopic Liver Transplantation: A Pilot Study

The incidence of primary nonfunction (PNF) after liver transplantation (LT) remains a major concern with the increasing use of marginal grafts. Indocyanine green (ICG) fluorescence is an imaging technique used in hepatobiliary surgery and LT. Because few early predictors are available, we aimed to quantify in real time the fluorescence of grafts during LT to predict 3-month survival. After graft revascularization, ICG was intravenously injected, and then the fluorescence of the graft was captured with a near infrared camera and postoperatively quantified. A multiparametric modeling of the parenchymal fluorescence intensity (FI) curve was proposed, and a predictive model of graft survival was tested. Between July 2017 and May 2019, 76 LTs were performed, among which 6 recipients underwent retransplantation. No adverse effects of ICG injection were observed. The parameter a₁₅₀ (temporal course of FI) was significantly higher in the re-LT group (0.022 seconds^-1 (0.0011-0.059) versus 0.012 seconds^-1 (0.0001-0.054); P = 0.01). This parameter was the only independent predictive factor of graft survival at 3 months (OR, 2.4; 95% CI, 1.05-5.50; P = 0.04). The best cutoff for the parameter a₁₅₀ (0.0155 seconds^-1 ) predicted the graft survival at 3 months with a sensitivity (Se) of 83.3% and a specificity (Spe) of 78.6% (area under the curve, 0.82; 95% CI, 0.67-0.98; P = 0.01). Quantitative assessment of intraoperative ICG fluorescence on the graft was feasible to predict graft survival at 3 months with a good Se and Spe. Further prospective studies should be undertaken to validate these results over larger cohorts and evaluate the clinical impact of this tool.

Hyperspectral evaluation of hepatic oxygenation in a model of total vs. arterial liver ischaemia

Liver ischaemia reperfusion injury (IRI) is a dreaded pathophysiological complication which may lead to an impaired liver function. The level of oxygen hypoperfusion affects the level of cellular damage during the reperfusion phase. Consequently, intraoperative localisation and quantification of oxygen impairment would help in the early detection of liver ischaemia. To date, there is no real-time, non-invasive, and intraoperative tool which can compute an organ oxygenation map, quantify and discriminate different types of vascular occlusions intraoperatively. Hyperspectral imaging (HSI) is a non-invasive optical methodology which can quantify tissue oxygenation and which has recently been applied to the medical field. A hyperspectral camera detects the relative reflectance of a tissue in the range of 500 to 1000 nm, allowing the quantification of organic compounds such as oxygenated and deoxygenated haemoglobin at different depths. Here, we show the first comparative study of liver oxygenation by means of HSI quantification in a model of total vascular inflow occlusion (VIO) vs. hepatic artery occlusion (HAO), correlating optical properties with capillary lactate and histopathological evaluation. We found that liver HSI could discriminate between VIO and HAO. These results were confirmed via cross-validation of HSI which detected and quantified intestinal congestion in VIO. A significant correlation between the near-infrared spectra and capillary lactate was found (r = − 0.8645, p = 0.0003 VIO, r = − 0.7113, p = 0.0120 HAO). Finally, a statistically significant negative correlation was found between the histology score and the near-infrared parameter index (NIR) (r = − 0.88, p = 0.004). We infer that HSI, by predicting capillary lactates and the histopathological score, would be a suitable non-invasive tool for intraoperative liver perfusion assessment.

Adenosine A2a Receptor Stimulation Attenuates Ischemia-Reperfusion Injury and Improves Survival in A Porcine Model of DCD Liver Transplantation

Orthotopic liver transplantation (OLT) using allografts from donation after circulatory death (DCD) is potentially associated with compromised clinical outcomes due to ischemia-reperfusion injury (IRI)-induced organ damage and graft-related complications. The aim of this study was to provide in vivo data on the effects of adenosine A2a receptor stimulation in a clinically relevant large animal model of DCD liver transplantation. Cardiac arrest was induced in German Landrace pigs (n = 10; 20-25 kg). After 30 min of warm ischemia, the donor liver was retrieved following a cold flush with 3 L of histidine-tryptophan-ketoglutarate-HTK solution. Animals of the treatment group (n = 5/group) received a standard dose of the selective adenosine receptor agonist CGS 21680 added to the cold flush. All grafts were stored for 4.5 h at 4 °C in HTK-solution before OLT. Hepatocellular injury, apoptosis, protein kinase A-PKA activity, graft microcirculation, liver function, and animal survival were assessed. Compared to untreated livers, adenosine A2a receptor stimulation resulted in improved tissue microcirculation (103% ± 5% vs. 38% ± 4% compared to baseline; p < 0.05), accelerated functional recovery of the graft (indocyanine green-plasma disappearance rate (ICG-PDR) of 75% ± 18% vs. 40% ± 30% after 3 h), increased PKA activity ratio (56% ± 3% vs. 32% ± 3%; p < 0.001 after 1 h), and consequently reduced tissue necrosis and apoptosis. The potent protective effects were clinically manifested in significantly improved survival in the treatment group after 72 h (100% vs. 40%; p = 0.04). The ex vivo administration of adenosine A2a receptor agonist during the back-table flush mitigates IRI-mediated tissue damage and improves functional graft recovery and survival in a large animal model of DCD liver transplantation.

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.

Serum Factor V Is a Continuous Biomarker of Graft Dysfunction and a Predictor of Graft Loss After Liver Transplantation

BACKGROUND

Factor V has never been compared to a validated early allograft dysfunction (EAD) definition. We aimed to assess factor V as a biomarker of EAD and a predictor of graft loss after liver transplantation (LT).

METHODS

We retrospectively assessed the serum factor V levels on postoperative day 1 after LT. Patients were divided according to their factor V levels into the ≤36.1 U/mL and > 36.1 U/mL groups. The primary outcome was graft loss within 1, 3, and 6 months. The secondary outcome was EAD, as defined by Olthoff et al. Predictors of outcomes were identified by multivariable logistic regression.

RESULTS

Two hundred twenty-seven patients were included in the study: 74 with factor V of 36.1 U/mL or less and 153 with factor V >36.1 U/mL. EAD was diagnosed in 41 (55.4%) of 74 patients with factor V of 36.1 U/mL or less and in 20/153 (13.1%) patients with factor V >36.1 U/mL (P < 0.001). According to the multivariable regression model, factor V was a continuous marker of EAD (odds ratio [OR], 0.96; 95% confidence interval [CI], 0.94-0.98 per U/mL). Among the study groups, the 1-, 3-, and 6-month graft survival rates were 82%, 74%, and 74%, respectively, for patients with factor V of 36.1 U/mL or less and 98%, 95%, and 95%, respectively, for patients with factor V >36.1 U/mL (P = 0.001). Factor V was a continuous predictor for 3- and 6-month graft losses (OR, 0.96; 95% CI, 0.94-0.99 and OR, 0.97; 95% CI, 0.94-0.99 per U/mL), whereas EAD was not significant when adjusted for factor V.

CONCLUSION

Factor V is an early marker for EAD and is a continuous predictor of short-term graft loss after LT.

Plasma Disappearance Rate of Indocyanine Green for Determination of Liver Function in Three Different Models of Shock

The measurement of the liver function via the plasma disappearance rate of indocyanine green (PDR_ICG) is a sensitive bed-side tool in critical care. Yet, recent evidence has questioned the value of this method for hyperdynamic conditions. To evaluate this technique in different hemodynamic settings, we analyzed the PDR_ICG and corresponding pharmacokinetic models after endotoxemia or hemorrhagic shock in rats. Male anesthetized Sprague-Dawley rats underwent hemorrhage (mean arterial pressure 35 ± 5 mmHg, 90 min) and 2 h of reperfusion, or lipopolysaccharide (LPS) induced moderate or severe (1.0 vs. 10 mg/kg) endotoxemia for 6 h (each n = 6). Afterwards, PDR_ICG was measured, and pharmacokinetic models were analyzed using nonlinear mixed effects modeling (NONMEM^®). Hemorrhagic shock resulted in a significant decrease of PDR_ICG, compared with sham controls, and a corresponding attenuation of the calculated ICG clearance in 1- and 2-compartment models, with the same log-likelihood. The induction of severe, but not moderate endotoxemia, led to a significant reduction of PDR_ICG. The calculated ICG blood clearance was reduced in 1-compartment models for both septic conditions. 2-compartment models performed with a significantly better log likelihood, and the calculated clearance of ICG did not correspond well with PDR_ICG in both LPS groups. 3-compartment models did not improve the log likelihood in any experiment. These results demonstrate that PDR_ICG correlates well with ICG clearance in 1- and 2-compartment models after hemorrhage. In endotoxemia, best described by a 2-compartment model, PDR_ICG may not truly reflect the ICG clearance.

An efficient method for measuring plasma volume using indocyanine green dye

Plasma volume (PV) can be an important marker of health status and may affect the interpretation of plasma biomarkers, but is rarely measured due to the complexity and time required. Indocyanine green (ICG) is a water-soluble tricarbocyanine dye with a circulatory half-life of 2–3 min, allowing for quick clearance and repeated use. It is used extensively in medical diagnostic tests including ophthalmologic imaging, liver function, and cardiac output, particularly in critical care. ICG has been validated for measuring PV in humans, however previous work has provided minimal published details or has focused on a single aspect of the method. We aimed to develop a detailed, optimal protocol for the use of ICG to measure PV in women of reproductive age. We combined best practices from other studies and optimized the protocol for efficiency.

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This method reduces the time from blood collection to PV determination to ˜2 h and the amount of plasma required to estimate PV to 2.5 mL (1.5 mL before ICG injection and 1.0 mL post-injection).

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Participant inconvenience is reduced by inserting an intravenous (IV) catheter in only one arm, not both arms.

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Five post-injection plasma samples (2–5 min after ICG bolus) are enough to accurately develop the decay curve for plasma ICG concentration and estimate PV by extrapolation.

C-reactive protein at ICU admission as a marker of early graft dysfunction after liver transplant. A prospective, single-center cohort study

OBJECTIVE

To explore the behavior of C-reactive protein (CRP) after orthotopic liver transplantation (OLT) during the first postoperative days, and its usefulness as a marker of severe early allograft dysfunction (EAD).

DESIGN

A prospective, single-center cohort study was carried out.

SETTING

The Intensive Care Unit (ICU) of a regional hospital with a liver transplant program since 1997.

PATIENTS

The study comprised a total of 183 patients admitted to our ICU immediately after liver transplantation between 2009 and 2015.

VARIABLES OF INTEREST

C-reactive protein levels upon ICU admission and after 24 and 48h, severe EAD and hospital mortality.

RESULTS

The CRP levels after OLT were: upon ICU admission 57.5 (51.6-63.3)mg/L, after 24h 80.1 (72.9-87.3)mg/L and after 48h 69.9 (62.5-77.4)mg/L. Severe EAD patients (14.2%) had higher mortality (23.1 vs 2.5; OR 11.48: 2.98-44.19) and lower CRP upon ICU admission (39.3 [29.8-48.7]mg/L) than the patients without EAD (0.5 [53.9-67.0]; p<0.05] - the best cut-off point being 68mg/L (sensitivity 92.3%; specificity 40.1%; Youden index 0.33). Lower CRP upon ICU admission was correlated to higher mortality (24.5 [9.2-39.7] vs 59.4 [53.4-65.4]; p<0.01, AUC 0.79 [0.65-0.92]).

CONCLUSION

Liver transplant is a strong inflammatory stimulus accompanied by high levels of C-reactive protein. A blunted rise in CRP on the first postoperative day after OLT may be a marker of poor allograft function and is related to hospital mortality.

Minimally invasive method for the point-of-care quantification of lymphatic vessel function

Current clinical methods for the evaluation of lymphatic vessel function, crucial for early diagnosis and evaluation of treatment response of several pathological conditions, in particular of postsurgical lymphedema, are based on complex and mainly qualitative imaging techniques. To address this unmet medical need, we established a simple strategy for the painless and quantitative assessment of cutaneous lymphatic function. We prepared a lymphatic-specific tracer formulation, consisting of the clinically approved near-infrared fluorescent dye, indocyanine green, and the solubilizing surfactant Kolliphor HS15. The tracer was noninvasively delivered to the dermal layer of the skin using MicronJet600 hollow microneedles, and the fluorescence signal decay at the injection site was measured over time using a custom-made, portable detection device. The decay rate of fluorescence signal in the skin was used as a direct measure of lymphatic vessel drainage function. With this method, we could quantify impaired lymphatic clearance in transgenic mice lacking dermal lymphatics and distinguish distinct lymphatic clearance patterns in pigs in different body locations and under manual stimulus. Overall, this method has the potential for becoming a noninvasive and quantitative clinical "office test" for lymphatic function assessment.

Radiation-Induced Liver Disease and Modern Radiotherapy

Modern radiotherapy techniques have enabled high focal doses of radiation to be delivered to patients with primary and secondary malignancies of the liver. The current clinical practice of radiation oncology has benefitted from decades of research that have informed how to achieve excellent local control and survival outcomes with minimal toxicities. Still, one of the most devastating consequences of radiation to the liver remains a challenge: radiation-induced liver disease (RILD). Here, we will review the current understanding of classic and nonclassic RILD from a clinical perspective, the evaluation and management of patients who are at risk of developing RILD, methods to reduce the likelihood of RILD using modern radiation techniques, and the diagnosis and treatment of radiation-related liver toxicities.

Early graft dysfunction after liver transplant: Comparison of different diagnostic criteria in a single-center prospective cohort

OBJECTIVE

Comparison of different diagnostic criteria for early liver allograft dysfunction (EAD) and their capability to predict mortality.

DESIGN

Single-center, prospective, cohort study.

SETTINGS

ICU in a Regional Hospital with a liver transplant program since 1997.

PATIENTS

253 consecutive patients admitted to our ICU immediately after liver transplantation between 2009 and 2015.

VARIABLES OF INTEREST

Differences in the incidence of EAD and its relation with ICU, Hospital and 2-year mortality depending on the definition applied using as comparator the UNOS (United Network for Organ Sharing) primary non-function criterion.

RESULTS

The incidence of early liver allograft dysfunction according to UNOS was 13.8%, to Makowka 6.3%, to Ardite 10.7%, to Nanashima 20.6%, to Dhillon 30.8% and to MEAF 13.4%. Kappa test did not show a good correlation among these criteria. EAD was related with ICU mortality for all diagnostic criteria except Dhillon but only UNOS, Makowka and MEAF were associated with 2-year mortality. Hospital mortality was poorly predicted by all criteria except for the MEAF score.

CONCLUSION

We found a poor agreement between different criteria analyzed for the diagnosis of EAD. In our population, the MEAF score showed the best relationship with short- and long-term mortality.

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.

Noninvasive monitoring of nanoparticle clearance and aggregation in blood circulation by in vivo flow cytometry

Nanoparticles have been widely used in biomedical research as drug carriers or imaging agents for living animals. Blood circulation is crucial for the delivery of nanoparticles, which enter the bloodstream through injection, inhalation, or dermal exposure. However, the clearance kinetics of nanoparticles in blood circulation has been poorly studied, mainly because of the limitations of conventional detection methods, such as insufficient blood sample volumes or low spatial-temporal resolution. In addition, formation of nanoparticle aggregates is a key determinant for biocompatibility and drug delivery efficiency. Aggregation behavior of nanoparticles in blood is studied using dynamic light scattering in serum or serum protein solutions, which is still very different from in vivo condition. In this work, we monitored the dynamics of nanoparticle concentration and formation of nanoparticle aggregates in the bloodstream in live animals using in vivo flow cytometry (IVFC). The results indicated that nanoparticles in smaller size could stay longer in the bloodstream. Polyethylene glycol (PEG)-modification could prolong circulating time and reduce the formation of aggregates in the blood circulation. Our work shows that IVFC can be a powerful tool for pharmacokinetic studies of nanoparticles and other drug carriers, assessing cell-targeting efficiency, as well as potentially measuring cardiac output and hepatic function in vivo.

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.

ICG Clearance Test and 99mTc-GSA SPECT/CT Fusion Images

Preoperative estimation of future remnant liver function is critical for major hepatic surgery to avoid postoperative morbidity and mortality. Among several liver function tests, the indocyanine green (ICG) clearance test is still the most popular dynamic method. The usefulness of ICG clearance test parameters, such as ICGR15, KICG, or PDRICG, has been reported by many investigators. The transcutaneous non-invasive pulse dye densitometry system has made the ICG clearance test more convenient and attractive, even in Western countries. The concept of future remnant KICG (rem KICG), which combines the functional aspect and the volumetric factor of the future remnant liver, seems ideal for determining the maximum extent of major hepatic resection that will not cause postoperative liver failure. For damaged livers with functional heterogeneity among the hepatic segments, fusion images combining technetium-99m-diethylenetriaminepentaacetic acid-galactosyl human serum albumin single photon emission computed tomography (99mTc-GSA SPECT) and X-ray CT are helpful to precisely estimate the functional reserve of the future remnant liver. Another technique for image-based liver function estimation, gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid(Gd-EOB)-enhanced magnetic resonance imaging, may be an ideal candidate for the preoperative determination of future remnant liver function. Using these methods effectively, morbidity and mortality after major hepatic resection could be reduced.

Donor Indocyanine Green Clearance Test Predicts Graft Quality and Early Graft Prognosis After Liver Transplantation

BACKGROUND

Transplantation centers have given much attention to donor availability. However, no reliable quantitative methods have been employed to accurately assess graft quality before transplantation. Here, we report that the indocyanine green (ICG) clearance test is a valuable index for liver grafts.

METHODS

We performed the ICG clearance test on 90 brain-dead donors within 6 h before organ procurement between March 2015 and November 2016. We also analyzed the relationship between graft liver function and early graft survival after liver transplantation (LT).

RESULTS

Our results suggest that the ICG retention rate at 15 min (ICGR15) of donors before procurement was independently associated with 3-month graft survival after LT. The best donor ICGR15 cutoff value was 11.0%/min, and we observed a significant increase in 3-month graft failure among patients with a donor ICGR15 above this value. On the other hand, a donor ICGR15 value of ≤ 11.0%/min could be used as an early assessment index of graft quality because it provides additional information to the transplant surgeon or organ procurement organization members who must maintain or improve organ function to adapt the LT.

CONCLUSION

An ICG clearance test before liver procurement might be an effective quantitative method to predict graft availability and improve early graft prognosis after LT.

Assessment of liver perfusion and function by indocyanine green in the perioperative setting and in critically ill patients

Indocyanine green (ICG) is a water-soluble dye that is bound to plasma proteins when administered intravenously and nearly completely eliminated from the blood by the liver. ICG elimination depends on hepatic blood flow, hepatocellular function and biliary excretion. ICG elimination is considered as a useful dynamic test describing liver function and perfusion in the perioperative setting, i.e., in liver surgery and transplantation, as well as in critically ill patients. ICG plasma disappearance rate (ICG-PDR) which can be measured today by transcutaneous systems at the bedside is a valuable method for dynamic assessment of liver function and perfusion, and is regarded as a valuable prognostic tool in predicting survival of critically ill patients, presenting with sepsis, ARDS or acute liver failure.

The combination of indocyanine green clearance test and model for end-stage liver disease score predicts early graft outcome after liver transplantation

Early allograft dysfunction (EAD) and early postoperative complications are two important clinical endpoints when evaluating clinical outcomes of liver transplantation (LT). We developed and validated two ICGR15-MELD models in 87 liver transplant recipients for predicting EAD and early postoperative complications after LT by incorporating the quantitative liver function tests (ICGR15) into the MELD score. Eighty seven consecutive patients who underwent LT were collected and divided into a training cohort (n = 61) and an internal validation cohort (n = 26). For predicting EAD after LT, the area under curve (AUC) for ICGR15-MELD score was 0.876, with a sensitivity of 92.0% and a specificity of 75.0%, which is better than MELD score or ICGR15 alone. The recipients with a ICGR15-MELD score ≥0.243 have a higher incidence of EAD than those with a ICGR15-MELD score <0.243 (P <0.001). For predicting early postoperative complications, the AUC of ICGR15-MELD score was 0.832, with a sensitivity of 90.9% and a specificity of 71.0%. Those recipients with an ICGR15-MELD score ≥0.098 have a higher incidence of early postoperative complications than those with an ICGR15-MELD score <0.098 (P < 0.001). Finally, application of the two ICGR15-MELD models in the validation cohort still gave good accuracy (AUC, 0.835 and 0.826, respectively) in predicting EAD and early postoperative complications after LT. The combination of quantitative liver function tests (ICGR15) and the preoperative MELD score is a reliable and effective predictor of EAD and early postoperative complications after LT, which is better than MELD score or ICGR15 alone.

Hepatocyte Concentrations of Indocyanine Green Reflect Transfer Rates Across Membrane Transporters

Perioperative imaging with indocyanine green (ICG) is developing to increase safety in dissecting anatomical structures during hepatobiliary surgery. Images obtained with the fluorescence camera rely on concentrations measured in liver regions of interest. However, how ICG sinusoidal uptake and hepatocyte elimination rates generate ICG hepatocyte concentrations is largely unknown. To investigate such issue and better understand the role of membrane transporters in generating ICG hepatocyte concentrations, we perfused ICG in livers isolated from normal livers. Whether the well-known transporter inhibitor rifampicin modifies hepatocyte ICG concentrations was also studied. The dye has a very high and constant extraction ratio (96%) into hepatocytes. This persistent high extraction ratio generates a huge uphill concentration gradient across the sinusoidal membrane: from 5 μM (sinusoids) to 1600 μM (liver). When inside hepatocytes, ICG has low hepatocyte elimination (7 nmol/min.) and liver concentrations do not decrease much over time. Moreover, the tiny hepatocyte ICG efflux is mainly due to ICG return back to sinusoids (90%). Rifampicin slightly inhibits ICG uptake into hepatocytes and when inside hepatocytes blocks ICG efflux into bile canaliculi. In contrast, it increases ICG efflux back to sinusoids with significant decrease in ICG liver concentrations. Imaging with ICG in the perioperative period reflects the high hepatocyte concentrations and relies on the high extraction ratio across hepatocyte sinusoidal membrane. Although ICG concentrations are low in bile ducts, they are adequate for a good visualization and avoid bile duct injury.

Predictive factors of short term outcome after liver transplantation: A review

Liver transplantation represents a fundamental therapeutic solution to end-stage liver disease. The need for liver allografts has extended the set of criteria for organ acceptability, increasing the risk of adverse outcomes. Little is known about the early postoperative parameters that can be used as valid predictive indices for early graft function, retransplantation or surgical reintervention, secondary complications, long intensive care unit stay or death. In this review, we present state-of-the-art knowledge regarding the early post-transplantation tests and scores that can be applied during the first postoperative week to predict liver allograft function and patient outcome, thereby guiding the therapeutic and surgical decisions of the medical staff. Post-transplant clinical and biochemical assessment of patients through laboratory tests (platelet count, transaminase and bilirubin levels, INR, factor V, lactates, and Insulin Growth Factor 1) and scores (model for end-stage liver disease, acute physiology and chronic health evaluation, sequential organ failure assessment and model of early allograft function) have been reported to have good performance, but they only allow late evaluation of patient status and graft function, requiring days to be quantified. The indocyanine green plasma disappearance rate has long been used as a liver function assessment technique and has produced interesting, although not univocal, results when performed between the 1^th and the 5^th day after transplantation. The liver maximal function capacity test is a promising method of metabolic liver activity assessment, but its use is limited by economic cost and extrahepatic factors. To date, a consensual definition of early allograft dysfunction and the integration and validation of the above-mentioned techniques, through the development of numerically consistent multicentric prospective randomised trials, are necessary. The medical and surgical management of transplanted patients could be greatly improved by using clinically reliable tools to predict early graft function.

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.

Intraoperative simulation of remnant liver function during anatomic liver resection with indocyanine green clearance (LiMON) measurements

OBJECTIVE

Post-hepatectomy liver failure (PHLF) is the major cause of death following liver resection. The aim of this study was to evaluate the feasibility of an intraoperative simulation of post-resection liver function.

METHODS

Intraoperative liver function was measured by indocyanine green (ICG) clearance using the LiMON technology. In 20 patients undergoing anatomic liver resection, ICG plasma disappearance rate (PDR (%/min) and ICG retention at 15 min (R15 ) (%) were measured immediately after the induction of anaesthesia (t0 ), after selective arterial and portovenous inflow trial clamping (TC) of the resected liver segments (t1 ), after the completion of resection (t2 ) and before the closure of the abdominal cavity (t3 ).

RESULTS

The median baseline (t0 ) PDR was 16.5%/min. Trial clamping of the inflow (t1 ) resulted in a significant reduction in PDR to 10.5%/min. Results under TC were similar to those obtained after resection (t2 ) (median PDR: 10.5%/min). Linear regression modelling showed that post-resection liver volume could be accurately predicted by TC of liver inflow (P < 0.0001), but not by determining the resected liver volume. Simulated post-resection liver function under TC correlated well with PHLF and length of hospital stay.

CONCLUSIONS

Intraoperative ICG clearance measurements allow real-time monitoring of intraoperative liver function during surgery. Trial clamping of arterial and portovenous inflow accurately predicts immediate post-resection liver function. The intraoperative measurement of liver function and simulation of post-resection liver function may help to avoid PHLF.

Assessment of Liver Remnant Using ICG Clearance Intraoperatively during Vascular Exclusion: Early Experience with the ALIIVE Technique

Background. The most significant risk following major hepatectomy is postoperative liver insufficiency. Current preoperative assessment of the future liver remnant relies upon assumptions which may not be valid in the setting of advanced resection strategies. This paper reports the feasibility of the ALIIVE technique which assesses the liver remnant with ICG clearance intraoperatively during vascular exclusion. Methods. 10 patients undergoing planned major liver resection (hemihepatectomy or greater) were recruited. Routine preoperative assessment included CT and standardized volumetry. ICG clearance was measured noninvasively using a finger spectrophotometer at various time points including following parenchymal transection during inflow and outflow occlusion before vascular division, the ALIIVE step. Results. There were one case of mortality and three cases of posthepatectomy liver failure. The patient who died had the lowest ALIIVE ICG clearance (7.1%/min versus 14.4 ± 4.9). Routine preoperative CT and standardized volumetry did not predict outcome. Discussion/Conclusion. The novel ALIIVE technique is feasible and assesses actual future liver remnant function before the point of no return during major hepatectomy. This technique may be useful as a check step to offer a margin of safety to prevent posthepatectomy liver failure and death. Further confirmatory studies are required to determine a safety cutoff level.

Noninvasive assessment of liver function

PURPOSE OF REVIEW

It is our opinion that there is an unmet need in hepatology for a minimally or noninvasive test of liver function and physiology. Quantitative liver function tests define the severity and prognosis of liver disease by measuring the clearance of substrates whose uptake or metabolism is dependent upon liver perfusion or hepatocyte function. Substrates with high-affinity hepatic transporters exhibit high 'first-pass' hepatic extraction and their clearance measures hepatic perfusion. In contrast, substrates metabolized by the liver have low first-pass extraction and their clearance measures specific drug metabolizing pathways.

RECENT FINDINGS

We highlight one quantitative liver function test, the dual cholate test, and introduce the concept of a disease severity index linked to clinical outcome that quantifies the simultaneous processes of hepatocyte uptake, clearance from the systemic circulation, clearance from the portal circulation, and portal-systemic shunting.

SUMMARY

It is our opinion that dual cholate is a relevant test for defining disease severity, monitoring the natural course of disease progression, and quantifying the response to therapy.

[Monitoring of liver function in the critically ill]

Liver failure and hepatic dysfunction represent diagnostic and therapeutic challenges for the intensivist. Besides acute liver failure, hypoxic hepatitis, sepsis and (secondary) sclerosing cholangitis may lead to massive liver dysfunction with subsequent multiorgan dysfunction syndrome that limits survival. Among classical laboratory parameters (so-called static liver parameters) liver function tests may help with the diagnosis to allow early treatment or prevention of liver dysfunction. The aim of this article is to present the current aspects of liver function monitoring and to provide guidelines to the intensivist for diagnosing liver dysfunction in the intensive care setting.

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.

Biomarkers to assess graft quality during conventional and machine preservation in liver transplantation

A global rising organ shortage necessitates the use of extended criteria donors (ECD) for liver transplantation (LT). However, poor preservation and extensive ischemic injury of ECD grafts have been recognized as important factors associated with primary non-function, early allograft dysfunction, and biliary complications after LT. In order to prevent for these ischemia-related complications, machine perfusion (MP) has gained interest as a technique to optimize preservation of grafts and to provide the opportunity to assess graft quality by screening for extensive ischemic injury. For this purpose, however, objective surrogate biomarkers are required which can be easily determined at time of graft preservation and the various techniques of MP. This review provides an overview and evaluation of biomarkers that have been investigated for the assessment of graft quality and viability testing during different types of MP. Moreover, studies regarding conventional graft preservation by static cold storage (SCS) were screened to identify biomarkers that correlated with either allograft dysfunction or biliary complications after LT and which could potentially be applied as predictive markers during MP. The pros and cons of the different biomaterials that are available for biomarker research during graft preservation are discussed, accompanied with suggestions for future research. Though many studies are currently still in the experimental setting or of low evidence level due to small cohort sizes, the biomarkers presented in this review provide a useful handle to monitor recovery of ECD grafts during clinical MP in the near future.

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.

How do transplant surgeons accomplish optimal portal venous flow during living-donor liver transplantation? Noninvasive measurement of indocyanine green elimination rate

BACKGROUND

Balancing donor safety and graft volume is difficult. We previously reported that intentional modulation of portal venous pressure (PVP) during living-donor liver transplantation (LDLT) is crucial to overcoming problems with small-for-size grafts; however, detailed studies of portal venous flow (PVF) and a reliable parameter are still required.

PATIENTS AND METHODS

The elimination rate (k) of indocyanine green (ICG) was measured in 49 adult LDLT recipients. PVP was controlled during LDLT, with a target of <20 mm Hg. ICG reflects hepatocyte volume and effective PVF. The kICG value is divided by the graft weight to calculate PVF. Recipients were divided into 2 groups: those with severe and/or fatal complications within 1 month after LDLT and those without.

RESULTS

Survival rates and postoperative profiles were significantly different between the 2 groups. Univariate analysis showed significant differences in ABO blood group, final PVP, final kICG, and the final kICG/graft weight value; however, multivariate analysis showed that only the kICG/graft weight value was significant. The cutoff level for the final kICG/graft weight value for predicting successful LDLT was 3.1175 × 10(-4)/g.

CONCLUSION

Accurate evaluation and monitoring of optimal PVF during LDLT should overcome the use of small-for-size grafts and improve donor safety and recipient outcomes.

How to assess liver function?

PURPOSE OF REVIEW

The liver comprises a multitude of parenchymal and nonparenchymal cells with diverse metabolic, hemodynamic and immune functions. Available monitoring options consist of 'static' laboratory parameters, quantitative tests of liver function based on clearance, elimination or metabolite formation and scores, most notably the 'model for end-stage liver disease'. This review aims at balancing conventional markers against 'dynamic' tests in the critically ill.

RECENT FINDINGS

There is emerging evidence that conventional laboratory markers, most notably bilirubin, and the composite model for end-stage liver disease are superior to assess cirrhosis and their acute decompensation, while dynamic tests provide information in the absence of preexisting liver disease. Bilirubin and plasma disappearance rate of indocyanine green reflecting static and dynamic indicators of excretory dysfunction prognosticate unfavorable outcome, both, in the absence and presence of chronic liver disease better than other functions or indicators of injury. Although dye excretion is superior to conventional static parameters in the critically ill, it still underestimates impaired canalicular transport, an increasingly recognized facet of excretory dysfunction.

SUMMARY

Progress has been made in the last year to weigh static and dynamic tests to monitor parenchymal liver functions, whereas biomarkers to assess nonparenchymal functions remain largely obscure.

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

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.

How transplant surgeons can overcome the inevitable insufficiency of allograft size during adult living-donor liver transplantation: strategy for donor safety with a smaller-size graft and excellent recipient results

Small-for-size grafts are an issue in liver transplantation. Portal venous pressure (PVP) was monitored and intentionally controlled during living-donor liver transplantation (LDLT) in 155 adult recipients. The indocyanine green elimination rate (kICG) was simultaneously measured in 16 recipients and divided by the graft weight (g) to reflect portal venous flow (PVF). The target PVP was <20 mmHg. Patients were divided by the final PVP (mmHg): Group A, PVP < 12; Group B, 12 ≤ PVP < 15; Group C, 15 ≤ PVP < 20; and Group D, PVP ≥ 20. With intentional PVP control, we performed splenectomy and collateral ligation in 80 cases, splenectomy in 39 cases, and splenectomy, collateral ligation, and additional creation in five cases. Thirty-one cases received no modulation. Groups A and B showed good LDLT results, while Groups C and D did not. Final PVP was the most important factor for the LDLT results, and the PVP cutoffs for good outcomes and clinical courses were both 15.5 mmHg. The respective kICG/graft weight cutoffs were 3.5580 × 10(-4) /g and 4.0015 × 10(-4) /g. Intentional PVP modulation at <15 mmHg is a sure surgical strategy for small-for-size grafts, to establish greater donor safety with good LDLT results. The kICG/graft weight value may have potential as a parameter for optimal PVF and a predictor for LDLT results.

Rapid measurement of indocyanine green retention by pulse spectrophotometry: a validation study in 70 patients with Child-Pugh A cirrhosis before hepatectomy for hepatocellular carcinoma

BACKGROUND

The indocyanine green (ICG) retention test is the most popular liver function test for selecting patients for major hepatectomy. Traditionally, it is done using spectrophotometry with serial blood sampling. The newly-developed pulse spectrophotometry is a faster alternative, but its accuracy on Child-Pugh A cirrhotic patients undergoing hepatectomy for hepatocellular carcinoma has not been well documented. This study aimed to assess the accuracy of the LiMON(®), one of the pulse spectrophotometry systems, in measuring preoperative ICG retention in these patients and to devise an easy formula for conversion of the results so that they can be compared with classical literature records where ICG retention was measured by the traditional method.

METHODS

We measured the liver function of 70 Child-Pugh A cirrhotic patients before hepatectomy for hepatocellular carcinoma from September 2008 to January 2009. ICG retention at 15 minutes measured by traditional spectrophotometry (ICGR15) was compared with ICG retention at 15 minutes measured by the LiMON (ICGR15(L)).

RESULTS

The median ICGR15 was 14.7% (5.6%-32%) and the median ICGR15(L) was 10.4% (1.2%-28%). The mean difference between them was -4.3606. There was a strong correlation between ICGR15 and ICGR15(L) (correlation coefficient, 0.844; 95% confidence interval, 0.762-0.899). The following formula was devised: ICGR15=1.16XICGR15(L)+2.73.

CONCLUSIONS

The LiMON provides a fast and repeatable way to measure ICG retention at 15 minutes, but with constant underestimation of the real value. Therefore, when comparing results obtained by traditional spectrophotometry and the LiMON, adjustment of results from the latter is necessary, and this can be done with a simple mathematical calculation using the above formula.

Liver injury due to chemotherapy-induced sinusoidal obstruction syndrome is associated with sinusoidal capillarization

BACKGROUND

Indocyanine green (ICG) retention is a validated test of hepatic function in patients with chronic liver disease. The underlying mechanism for the impairment of ICG retention in patients undergoing chemotherapy for colorectal liver metastases (CLM) remains unclear. We sought to elucidate the mechanism for impairment of ICG retention in patients with CLM.

METHODS

Clinicopathologic data of 98 patients with CLM undergoing hepatectomy were analyzed. The archived nontumoral liver parenchyma bearing no CLM were immunostained with CD34 antibody to determine the sinusoidal capillarization.

RESULTS

Of 98 patients, 80 received preoperative chemotherapy. Sinusoidal obstruction syndrome (SOS) occurred in 39 patients (39.8%). The development of SOS in patients receiving oxaliplatin-based chemotherapy was significantly higher compared to those receiving non-oxaliplatin-based chemotherapy (P=0.003). SOS was independently associated with abnormal ICG retention rate at 15 minutes (ICG-R15) (odds ratio 3.45, 95% confidence interval 1.31-9.04, P=0.012) and CD 34 overexpression (odds ratio 18.76, 95% confidence interval 4.58-76.81, P<0.001). ICG-R15 correlated with CD34 expression within the nontumoral liver parenchyma (r=0.707, P<0.001) and severity of SOS (r=0.423, P<0.001). CD34 positive areas were likely situated at the peripheral area of SOS, and both SOS score and number of cycles of oxaliplatin-based chemotherapy significantly correlated with CD34 expression (r=0.629, P<0.001 and r=0.522, P<0.001, respectively).

CONCLUSIONS

These results suggest that the deterioration of hepatic functional reserve due to SOS is associated with sinusoidal capillarization, indicated by CD34 overexpression within nontumoral liver parenchyma adjacent to SOS.

Non-invasive ICG-clearance: a useful tool for the management of hepatic artery thrombosis following liver transplantation

BACKGROUND

The clinical presentation of hepatic artery thrombosis (HAT) post-liver transplantation (LT) varies considerably. Doppler ultrasonography (Doppler US) is the first line investigation, with a diagnostic sensitivity for HAT as high as 92%. Because indocyanine green (ICG) elimination from the blood depends among other factors on the hepatic blood flow, we hypothesized that plasma disappearance rate of indocyanine green (PDR-ICG) can be influenced by the flow in the hepatic artery. Thus, we evaluated the role of PDR-ICG measurement in HAT diagnosis in post-LT patients.

PATIENTS AND METHODS

Fourteen liver transplant patients with no visible flow in the hepatic artery (Doppler US) were identified. Of the 14, seven patients had HAT confirmed by CT-angiography. The PDR-ICG measurement, an investigation routinely used in our center, was performed in all 14 patients.

RESULTS

The PDR-ICG in patients with HAT was significantly lower than in patients without HAT (5.8 ± 4.3 vs. 23.8 ± 7.4%/min, p= 0.0009). In patients with HAT, after the revascularization, the PDR-ICG value increased (5.8 ± 4.3 vs. 15.6 ± 3.5%/min, p = 0.006).

CONCLUSION

The ICG elimination may be an adjunct diagnostic tool in the management of patients with suspected HAT following LT.

Noninvasive indocyanine green plasma disappearance rate predicts early complications, graft failure or death after liver transplantation

BACKGROUND

Early detection of graft malfunction or postoperative complications is essential to save patients and organs after orthotopic liver transplantation (OLT). Predictive tests for graft dysfunction are needed to enable earlier implementation of organ-saving interventions following transplantation. This study was undertaken to assess the value of indocyanine green plasma disappearance rates (ICG-PDRs) for predicting postoperative complications, graft dysfunction, and patient survival following OLT.

METHODS

Eighty-six patients undergoing OLT were included in this single-centre trial. ICG-PDR was assessed daily for the first 7 days following OLT. Endpoints were graft loss or death within 30 days and postoperative complications, graft loss, or death within 30 days.

RESULTS

Postoperative complications of 31 patients included deaths (12 patients) or graft losses. ICG-PDR was significantly different in patients whose endpoints were graft loss or death beginning from day 3 and in those whose endpoints were graft-loss, death, or postoperative complications beginning from day 4 after OLT. For day 7 measurements, receiver operating characteristic curve analysis revealed an ICG-PDR cut-off for predicting death or graft loss of 9.6% per min (a sensitivity of 75.0%, a specificity of 72.6%, positive predictive value 0.35, negative predictive value 0.94). For prediction of graft loss, death, or postoperative complications, the ICG-PDR cut-off was 12.3% per min (a sensitivity of 68.9%, a specificity of 66.7%, positive predictive value 0.57, negative predictive value 0.77).

CONCLUSIONS

ICG-PDR measurements on postoperative day 7 are predictive of early patient outcomes following OLT. The added value over that of routinely determined laboratory parameters is low.