How to define initial poor graft function after liver transplantation? - a new functional definition by the LiMAx test

Defatting of donor transplant livers during normothermic perfusion-a randomised clinical trial: study protocol for the DeFat study

BACKGROUND

Liver disease is the third leading cause of premature death in the UK. Transplantation is the only successful treatment for end-stage liver disease but is limited by a shortage of suitable donor organs. As a result, up to 20% of patients on liver transplant waiting lists die before receiving a transplant. A third of donated livers are not suitable for transplant, often due to steatosis. Hepatic steatosis, which affects 33% of the UK population, is strongly associated with obesity, an increasing problem in the potential donor pool. We have recently tested defatting interventions during normothermic machine perfusion (NMP) in discarded steatotic human livers that were not transplanted. A combination of therapies including forskolin (NKH477) and L-carnitine to defat liver cells and lipoprotein apheresis filtration were investigated. These interventions resulted in functional improvement during perfusion and reduced the intrahepatocellular triglyceride (IHTG) content. We hypothesise that defatting during NMP will allow more steatotic livers to be transplanted with improved outcomes.

METHODS

In the proposed multi-centre clinical trial, we will randomly assign 60 livers from donors with a high-risk of hepatic steatosis to either NMP alone or NMP with defatting interventions. We aim to test the safety and feasibility of the defatting intervention and will explore efficacy by comparing ex-situ and post-reperfusion liver function between the groups. The primary endpoint will be the proportion of livers that achieve predefined functional criteria during perfusion which indicate potential suitability for transplantation. These criteria reflect hepatic metabolism and injury and include lactate clearance, perfusate pH, glucose metabolism, bile composition, vascular flows and transaminase levels. Clinical secondary endpoints will include proportion of livers transplanted in the two arms, graft function; cell-free DNA (cfDNA) at follow-up visits; patient and graft survival; hospital and ITU stay; evidence of ischemia-reperfusion injury (IRI); non-anastomotic biliary strictures and recurrence of steatosis (determined on MRI at 6 months).

DISCUSSION

This study explores ex-situ pharmacological optimisation of steatotic donor livers during NMP. If the intervention proves effective, it will allow the safe transplantation of livers that are currently very likely to be discarded, thereby reducing waiting list deaths.

TRIAL REGISTRATION

ISRCTN ISRCTN14957538. Registered in October 2022.

Immunomodulation by Hemoadsorption—Changes in Hepatic Biotransformation Capacity in Sepsis and Septic Shock: A Prospective Study

Background: Sepsis is often associated with liver dysfunction, which is an indicator of poor outcomes. Specific diagnostic tools that detect hepatic dysfunction in its early stages are scarce. So far, the immune modulatory effects of hemoadsorption with CytoSorb^® on liver function are unclear. Method: We assessed the hepatic function by using the dynamic LiMAx^® test and biochemical parameters in 21 patients with sepsis or septic shock receiving CytoSorb^® in a prospective, observational study. Points of measurement: T₁: diagnosis of sepsis or septic shock; T₂ and T₃: 24 h and 48 h after the start of CytoSorb^®; T₄: 24 h after termination of CytoSorb^®. Results: The hepatic biotransformation capacity measured by LiMAx^® was severely impaired in up to 95 % of patients. Despite a rapid shock reversal under CytoSorb^®, a significant improvement in LiMAx^® values appeared from T₃ to T₄. This decline and recovery of liver function were not reflected by common parameters of hepatic metabolism that remained mostly within the normal range. Conclusions: Hepatic dysfunction can effectively and safely be diagnosed with LiMAx^® in ventilated ICU patients under CytoSorb^®. Various static liver parameters are of limited use since they do not adequately reflect hepatic dysfunction and impaired hepatic metabolism.

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.

Perioperative rifaximin is not associated with enhanced functional and volumetric recovery after major liver resection

The objective of this randomized controlled trial (RCT) was to assess the impact of rifaximin on the course of liver function, liver regeneration and volumetric recovery in patients undergoing major hepatectomy. The ARROW trial was an investigator initiated, single-center, open-label, phase 3 RCT with two parallel treatment groups, conducted at our hepatobiliary center from 03/2016 to 07/2020. Patients undergoing major hepatectomy were eligible and randomly assigned 1:1 to receive oral rifaximin (550 mg twice daily for 7-10 or 14-21 days in case of portal vein embolization preoperatively and 7 days postoperatively) versus no intervention. Primary endpoint was the relative increase in postoperative liver function measured by LiMAx from postoperative day (POD) 4 to 7. Secondary endpoint were the course of liver function and liver volume during the study period as well as postoperative morbidity and mortality. Between 2016 and 2020, 45 patients were randomized and 35 patients (16 individuals in the rifaximin and 19 individuals in the control group) were eligible for per-protocol analysis. The study was prematurely terminated following interim analysis, due to the unlikelihood of reaching a significant primary endpoint. The median relative increase in liver function from POD 4 to POD 7 was 27% in the rifaximin group and 41% in the control group (p = 0.399). Further, no significant difference was found in terms of any other endpoints of functional liver- and volume regeneration or perioperative surgical complications following the application of rifaximin versus no intervention. Perioperative application of rifaximin has no effect on functional or volumetric regeneration after major hepatectomy (NCT02555293; EudraCT 2013-004644-28).

CT-Based Prediction of Liver Function and Post-PVE Hypertrophy Using an Artificial Neural Network

Background: This study aimed to evaluate whether hypertrophy after portal vein embolization (PVE) and maximum liver function capacity (LiMAx) are predictable by an artificial neural network (ANN) model based on computed tomography (CT) texture features. Methods: We report a retrospective analysis on 118 patients undergoing preoperative assessment by CT before and after PVE for subsequent extended liver resection due to a malignant tumor at RWTH Aachen University Hospital. The LiMAx test was carried out in a subgroup of 55 patients prior to PVE. Associations between CT texture features and hypertrophy as well as liver function were assessed by a multilayer perceptron ANN model. Results: Liver volumetry showed a median hypertrophy degree of 33.9% (16.5–60.4%) after PVE. Non-response, defined as a hypertrophy grade lower than 25%, was found in 36.5% (43/118) of the cases. The ANN prediction of the hypertrophy response showed a sensitivity of 95.8%, specificity of 44.4% and overall prediction accuracy of 74.6% (p < 0.001). The observed median LiMAx was 327 (248–433) μg/kg/h and was strongly correlated with the predicted LiMAx (R² = 0.89). Conclusion: Our study shows that an ANN model based on CT texture features is able to predict the maximum liver function capacity and may be useful to assess potential hypertrophy after performing PVE.

Metabonomic Profile of Macrosteatotic Allografts for Orthotopic Liver Transplantation in Patients With Initial Poor Function: Mechanistic Investigation and Prognostic Prediction

BACKGROUND

Our previous study revealled amplified hazardous effects of macrosteatosis (MaS) on graft failure (GF) in recipients with severe liver damage in short post-operative days, with vague mechanism inside.

AIM

We aimed to uncover the molecular mechanism of donor MaS on GF, and construct the predictive model to monitor post-transplant prognosis based on "omics" perspective.

METHODS

Ultra-performance liquid chromatography coupled to mass spectrometry metabolomic analysis was performed in allograft tissues from 82 patients with initial poor function (IPF) from multi-liver transplant (LT) centers. Pathway analysis was performed by on-line toolkit Metaboanalyst (v 3.0). Predictive model was constructed based on combinative metabonomic and clinical data extracted by stepwised cox proportional analysis.

RESULTS

Principle component analysis (PCA) analysis revealled stratification on metabolic feature in organs classified by MaS status. Differential metabolits both associated with MaS and GF were significantly enriched on pathway of glycerophospholipid metabolism (P < 0.05). Phosphatidylcholine (PC) and phosphatidylethanolamine (PE) involved in glycerophospholipid metabolism was significantly decreased in cases with MaS donors and GF (P < 0.05). Better prediction was observed on graft survival by combinative model (area under the curve = 0.91) and confirmed by internal validation.

CONCLUSION

Metabonomic features of allografts can be clearly distinguished by MaS status in patients with IPF. Dysfunction on glycerophospholipid metabolism was culprit to link donor MaS and final GF. Decrement on PC and PE exerted the fatal effects of MaS on organ failure. Metabonomic data might help for monitoring long-term graft survival after LT.

Assessing Non-Invasive Liver Function in Patients with Intestinal Failure Receiving Total Parenteral Nutrition-Results from the Prospective PNLiver Trial

Liver abnormalities in intestinal failure (IF) patients receiving parenteral nutrition (PN) can progress undetected by standard laboratory tests to intestinal failure associated liver disease (IFALD). The aim of this longitudinal study is to evaluate the ability of non-invasive liver function tests to assess liver function following the initiation of PN. Twenty adult patients with IF were prospectively included at PN initiation and received scheduled follow-up assessments after 6, 12, and 24 months between 2014 and 2019. Each visit included liver assessment (LiMAx [Liver Maximum Capacity] test, ICG [indocyanine green] test, FibroScan), laboratory tests (standard laboratory test, NAFLD [non-alcoholic fatty liver disease] score, FIB–4 [fibrosis-4] score), nutritional status (bioelectrical impedance analysis, indirect calorimetry), and quality of life assessment. The patients were categorized post-hoc based on their continuous need for PN into a reduced parenteral nutrition (RPN) group and a stable parenteral nutrition (SPN) group. While the SPN group (n = 9) had significantly shorter small bowel length and poorer nutritional status at baseline compared to the RPN group (n = 11), no difference in liver function was observed between the distinct groups. Over time, liver function determined by LiMAx did continuously decrease from baseline to 24 months in the SPN group but remained stable in the RPN group. This decrease in liver function assessed with LiMAx in the SPN group preceded deterioration of all other investigated liver function tests during the study period. Our results suggest that the liver function over time is primarily determined by the degree of intestinal failure. Furthermore, the LiMAx test appeared more sensitive in detecting early changes in liver function in comparison to other liver function tests.

Hepatic flow is an intraoperative predictor of early allograft dysfunction in whole-graft deceased donor liver transplantation: An observational cohort study

BACKGROUND

Early allograft dysfunction (EAD) after liver transplantation (LT) is an important cause of morbidity and mortality. To ensure adequate graft function, a critical hepatocellular mass is required in addition to an appropriate blood supply. We hypothesized that intraoperative measurement of portal venous and hepatic arterial flow may serve as a predictor in the diagnosis of EAD.

AIM

To study whether hepatic flow is an independent predictor of EAD following LT.

METHODS

This is an observational cohort study in a single institution. Hepatic arterial blood flow and portal venous blood flow were measured intraoperatively by transit flow. EAD was defined using the Olthoff criteria. Univariate and multivariate analyses were used to determine the intraoperative predictors of EAD. Survival analysis and prognostic factor analysis were performed using the Kaplan-Meier and Cox regression models.

RESULTS

A total of 195 liver transplant procedures were performed between January 2008 and December 2014 in 188 patients. A total of 54 (27.7%) patients developed EAD. The median follow-up was 39 mo. Portal venous flow, hepatic arterial flow (HAF) and total hepatic arterial flow were associated with EAD in both the univariate and multivariate analyses. HAF is an independent prognostic factor for 30-d patient mortality.

CONCLUSION

Intraoperative measurement of blood flow after reperfusion appears to be a predictor of EAD; Moreover, HAF should be considered a predictor of 30-d patient mortality.

Monitoring Liver Function of Patients Undergoing Transarterial Chemoembolization (TACE) by a 13C Breath Test (LiMAx)

PURPOSE

Transarterial chemoembolization (TACE) is associated with the risk of deteriorating liver function, especially in patients with preexisting liver damage. Current liver function tests may fail to accurately predict the functional liver reserve. Aim of this study was to investigate whether changes of liver function caused by TACE are associated with detectable changes of LiMAx values.

METHODS AND MATERIALS

Forty patients with primary or secondary liver cancer underwent TACE and LiMAx test on the day before, the day after, and 4 weeks after TACE. LiMAx results were evaluated, referenced to liver volume (CT/MR volumetry), correlated with the respective TACE volume (subsegmental vs. segmental vs. lobar), established liver function tests, and Child-Pugh and ALBI scores.

RESULTS

The individual LiMAx values were significantly reduced by 10% (p = 0.01) on the day after TACE and fully recovered to baseline 1 month after treatment. Similar changes were observed regarding levels of bilirubin, transaminases, albumin, INR, and creatinine. LiMAx did not correlate significantly with the treated liver volume, but did correlate with the baseline liver volume (< 1200 ml vs. > 1200 ml; p < 0.01). No significant changes were observed in the Child-Pugh score or ALBI score.

CONCLUSION

LiMAx is capable of detecting changes in liver function, even modulations caused by superselective TACE procedures. Accordingly, it could be used as a tool for patient selection and monitoring of transarterial therapy. In comparison, Child-Pugh and ALBI scores did not reflect any of these changes. Some biochemical parameters also changed significantly after TACE, but they tend to be less specific in providing sufficient information on actual cellular dysfunction.

Prospective Assessment of Liver Function by an Enzymatic Liver Function Test to Estimate Short-Term Survival in Patients with Liver Cirrhosis

BACKGROUND

MELD attempts to objectively predict the risk of mortality of patients with liver cirrhosis and is commonly used to prioritize organ allocation. Despite the usefulness of the MELD, updated metrics could further improve the accuracy of estimates of survival.

AIMS

To assess and compare the prognostic ability of an enzymatic ¹³C-based liver function test (LiMAx) and distinct markers of liver function to predict 3-month mortality of patients with chronic liver failure.

METHODS

We prospectively investigated liver function of 268 chronic liver failure patients without hepatocellular carcinoma. Primary study endpoint was liver-related death within 3 months of follow-up. Prognostic values were calculated using Cox proportional hazards and logistic regression analysis.

RESULTS

The Cox proportional hazard model indicated that LiMAx (p < 0.001) and serum creatinine values (p < 0.001) were the significant parameters independently associated with the risk of liver failure-related death. Logistic regression analysis revealed LiMAx and serum creatinine to be independent predictors of mortality. Areas under the receiver-operating characteristic curves for MELD (0.86 [0.80-0.92]) and for a combined score of LiMAx and serum creatinine (0.83 [0.76-0.90]) were comparable.

CONCLUSIONS

Apart from serum creatinine levels, enzymatic liver function measured by LiMAx was found to be an independent predictor of short-term mortality risk in patients with liver cirrhosis. A risk score combining both determinants allows reliable prediction of short-term prognosis considering actual organ function. Trial Registration Number (German Clinical Trials Register) # DRKS00000614.

Graft Dysfunction and Management in Liver Transplantation

Graft dysfunction of the liver allograft manifests across a spectrum in both timing posttransplantation and clinical presentation. This can range from mild transient abnormalities of liver tests to acute liver failure potentially leading to graft failure. The causes of graft dysfunction can be divided into those resulting in early and late graft dysfunction. Although nonspecific, liver biochemistry abnormalities are still the mainstay investigation used in monitoring for dysfunction. This article provides a summary of the main causes and management strategies for liver graft dysfunction in the early through late posttransplant stages.

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.

Rotational thromboelastometry (ROTEM) 24 hours post liver transplantation predicts early allograft dysfunction

Early allograft dysfunction (EAD) represents one of the most common and serious complications after liver transplantation (LT).

Methods

One hundred sixty-four patients who underwent LT were prospectively included in the present study. Patient demographics, intraoperative blood loss and transfusion were recorded at the time of LT. Lactate levels were recorded during surgery and daily for the first 3 postoperative days. Standard and derived rotational thromboelastometry (ROTEM) parameters were recorded 24 hours after LT. EAD was diagnosed according to Nanashima criteria and post anaesthesia care unit length of stay was recorded.

Results

Forty-seven patients (28.6%) developed EAD. Intraoperative blood loss (p = 0.01), packed red blood cells (p = 0.04) and fresh frozen plasma (p = 0.01) transfusion represented intraoperative risk factors for EAD. Lactate levels were significantly higher in patients with EAD at all time points. Patients with EAD demonstrated an increased clot formation time and decreased maximum clot firmness in both intrinsically (p < 0.01) and extrinsically (p < 0.01) activated assay, a decreased thrombin potential index (p < 0.01), area under the curve (p < 0.01) and clot elasticity (p < 0.01) on ROTEM assay.

Conclusion

Our results show that both standard and derived ROTEM parameters may indicate early signs of graft failure and can aid in the diagnosis of EAD.

Evaluation of two-point Dixon water-fat separation for liver specific contrast-enhanced assessment of liver maximum capacity

Gadoxetic acid-enhanced magnetic resonance imaging has become a useful tool for quantitative evaluation of liver capacity. We report on the importance of intrahepatic fat on gadoxetic acid-supported T1 mapping for estimation of liver maximum capacity, assessed by the realtime ¹³C-methacetin breathing test (¹³C-MBT). For T1 relaxometry, we used a respective T1-weighted sequence with two-point Dixon water-fat separation and various flip angles. Both T1 maps of the in-phase component without fat separation (T1_in) and T1 maps merely based on the water component (T1_W) were generated, and respective reduction rates of the T1 relaxation time (rrT1) were evaluated. A steady considerable decline in rrT1 with progressive reduction of liver function could be observed for both T1_in and T1_W (p < 0.001). When patients were subdivided into 3 different categories of ¹³C-MBT readouts, the groups could be significantly differentiated by their rrT1_in and rrT1_W values (p < 0.005). In a simple correlation model of ¹³C-MBT values with T1_inpost (r = 0.556; p < 0.001), T1_Wpost (r = 0.557; p < 0.001), rrT1_in (r = 0.711; p < 0.001) and rrT1_W (r = 0.751; p < 0.001), a log-linear correlation has been shown. Liver maximum capacity measured with ¹³C-MBT can be determined more precisely from gadoxetic acid-supported T1 mapping when intrahepatic fat is taken into account. Here, T1_W maps are shown to be significantly superior to T1_in maps without separation of fat.

Liver maximum capacity (LiMAx) test as a helpful prognostic tool in acute liver failure with sepsis: a case report

Background

Acute liver failure (ALF) is a life-threatening entity particularly when infectious complications worsen the clinical course. Urgent liver transplantation (LT) is frequently the only curative treatment. However, in some cases, recovery is observed under conservative treatment. Therefore, prognostic tools for estimating course of the disease are of great clinical interest. Since laboratory parameters sometimes lack sensitivity and specificity, enzymatic liver function measured by liver maximum capacity (LiMAx) test may offer novel and valuable additional information in this setting.

Case presentation

We here report the case of a formerly healthy 20-year old male caucasian patient who was admitted to our clinic for ALF of unknown origin in December 2017. Laboratory parameters confirmed the diagnosis with an initial MELD score of 28 points. Likewise, enzymatic liver function was significantly impaired with a value of 147 [> 315] μg/h/kg. Clinical and biochemical analyses for viral-, autoimmune-, or drug-induced hepatitis were negative. Liver synthesis parameters further deteriorated reaching a MELD score of 40 points whilst clinical course was complicated by septic pneumonia leading to severe hepatic encephalopathy grade III-IV, finally resulting in mechanical ventilation of the patient. Interestingly, although clinical course and laboratory data suggested poor outcome, serial LiMAx test revealed improvement of the enzymatic liver function at this time point increasing to 169 μg/h/kg. Clinical condition and laboratory data slowly improved likewise, however with significant time delay of 11 days. Finally, the patient could be dismissed from our clinic after 37 days.

Conclusion

Estimating prognosis in patients with ALF is challenging by use of the established scores. In our case, improvement of enzymatic liver function measured by the LiMAx test was the first parameter predicting beneficial outcome in a patient with ALF complicated by sepsis.

Randomized clinical trial comparing liver resection with and without perioperative assessment of liver function

Background

Liver function tests may help to predict outcomes after liver surgery. The aim of this study was to evaluate the clinical impact on postoperative outcome and patient management of perioperative liver function testing using the LiMAx^® test.

Methods

A multicentre RCT was conducted in six academic liver centres. Patients with intrahepatic tumours scheduled for open liver resection of at least one segment were eligible. Patients were randomized to undergo additional perioperative liver function tests (LiMAx^® group) or standard care (control group). Patients in the intervention arm received two perioperative LiMAx^® tests, one before the operation for surgical planning and another after surgery for postoperative management. The primary endpoint was the proportion of patients transferred directly to a general ward. Secondary endpoints were severe complications, length of hospital stay (LOS) and length of intermediate care/ICU (LOI) stay.

Results

Some 148 patients were randomized. Thirty‐six of 58 patients (62 per cent) in the LiMAx^® group were transferred directly to a general ward, compared with one of 60 (2 per cent) in the control group (P < 0·001). The rate of severe complications was significantly lower in the LiMAx^® group (14 per cent versus 28 per cent in the control group; P = 0·022). LOS and LOI were significantly shorter in the LiMAx^® group (LOS: 10·6 versus 13·3 days respectively, P = 0·012; LOI: 0·8 versus 3·0 days, P < 0·001).

Conclusion

Perioperative use of the LiMAx^® test improves postoperative management and reduces the incidence of severe complications after liver surgery. Registration number: NCT01785082 ( https://clinicaltrials.gov).

Hepatobiliary MRI: Signal intensity based assessment of liver function correlated to 13C-Methacetin breath test

Gadoxetic acid (Gd-EOB-DTPA) is a paramagnetic MRI contrast agent with raising popularity and has been used for evaluation of imaging-based liver function in recent years. In order to verify whether liver function as determined by real-time breath analysis using the intravenous administration of ¹³C-methacetin can be estimated quantitatively from Gd-EOB-DTPA-enhanced MRI using signal intensity (SI) values. 110 patients underwent Gd-EOB-DTPA-enhanced 3-T MRI and, for the evaluation of liver function, a ¹³C-methacetin breath test (¹³C-MBT). SI values from before (SI_pre) and 20 min after (SI_post) contrast media injection were acquired by T1-weighted volume-interpolated breath-hold examination (VIBE) sequences with fat suppression. The relative enhancement (RE) between the plain and contrast-enhanced SI values was calculated and evaluated in a correlation analysis of ¹³C-MBT values to SI_post and RE to obtain a SI-based estimation of ¹³C-MBT values. The simple regression model showed a log-linear correlation of ¹³C-MBT values with SI_post and RE (p < 0.001). Stratified by 3 different categories of ¹³C-MBT readouts, there was a constant significant decrease in both SI_post (p ≤ 0.002) and RE (p ≤ 0.033) with increasing liver disease progression as assessed by the ¹³C-MBT. Liver function as determined using real-time ¹³C-methacetin breath analysis can be estimated quantitatively from Gd-EOB-DTPA-enhanced MRI using SI-based indices.

Gd-EOB-DTPA-enhanced T1 relaxometry for assessment of liver function determined by real-time 13C-methacetin breath test

OBJECTIVES

To determine whether liver function as determined by intravenous administration of ¹³C-methacetin and continuous real-time breath analysis can be estimated quantitatively from gadoxetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance (MR) relaxometry.

METHODS

Sixty-six patients underwent a ¹³C-methacetin breath test (¹³C-MBT) for evaluation of liver function and Gd-EOB-DTPA-enhanced T1-relaxometry at 3 T. A transverse 3D VIBE sequence with an inline T1 calculation based on variable flip angles was acquired prior to (T1 pre) and 20 min post-Gd-EOB-DTPA (T1 post) administration. The reduction rate of T1 relaxation time (rrT1) and T1 relaxation velocity index (∆R1) between pre- and post-contrast images was evaluated. ¹³C-MBT values were correlated with T1_post, ∆R1 and rrT1, providing an MRI-based estimated ¹³C-MBT value. The interobserver reliability was assessed by determining the intraclass correlation coefficient (ICC).

RESULTS

Stratified by three different categories of ¹³C-MBT readouts, there was a constant increase of T1 post with increasing progression of diminished liver function (p ≤ 0.030) and a constant significant decrease of ∆R1 (p ≤ 0.025) and rrT1 (p < 0.018) with progression of liver damage as assessed by ¹³C-methacetin breath analysis. ICC for all T1 relaxation values and indices was excellent (> 0.88). A simple regression model showed a log-linear correlation of ¹³C-MBT values with T1_post (r = 0.57; p < 0.001), ∆R1 (r = 0.59; p < 0.001) and rrT1 (r = 0.70; p < 0.001).

CONCLUSION

Liver function as determined using real-time ¹³C-methacetin breath analysis can be estimated quantitatively from Gd-EOB-DTPA-enhanced MR relaxometry.

KEY POINTS

• Gd-EOB-DTPA-enhanced T1 relaxometry quantifies liver function • Gd-EOB-DTPA-enhanced MR relaxometry may provide parameters for assessing liver function before surgery • Gd-EOB-DTPA-enhanced MR relaxometry may be useful for monitoring liver disease progression • Gd-EOB-DTPA-enhanced MR relaxometry has the potential to become a novel liver function index.

From "Gut Feeling" to Objectivity: Machine Preservation of the Liver as a Tool to Assess Organ Viability

Purpose of Review

The purpose of this review was to summarise how machine perfusion could contribute to viability assessment of donor livers.

Recent Findings

In both hypothermic and normothermic machine perfusion, perfusate transaminase measurement has allowed pretransplant assessment of hepatocellular damage. Hypothermic perfusion permits transplantation of marginal grafts but as yet has not permitted formal viability assessment. Livers undergoing normothermic perfusion have been investigated using parameters similar to those used to evaluate the liver in vivo. Lactate clearance, glucose evolution and pH regulation during normothermic perfusion seem promising measures of viability. In addition, bile chemistry might inform on cholangiocyte viability and the likelihood of post-transplant cholangiopathy.

Summary

While the use of machine perfusion technology has the potential to reduce and even remove uncertainty regarding liver graft viability, analysis of large datasets, such as those derived from large multicenter trials of machine perfusion, are needed to provide sufficient information to enable viability parameters to be defined and validated .

Impact of liver volume and liver function on posthepatectomy liver failure after portal vein embolization- A multivariable cohort analysis

BACKGROUND

Liver failure remains a life-threatening complication after liver resection, and is difficult to predict preoperatively. This retrospective cohort study evaluated different preoperative factors in regard to their impact on posthepatectomy liver failure (PHLF) after extended liver resection and previous portal vein embolization (PVE).

METHODS

Patient characteristics, liver function and liver volumes of patients undergoing PVE and subsequent liver resection were analyzed. Liver function was determined by the LiMAx test (enzymatic capacity of cytochrome P450 1A2). Factors associated with the primary end point PHLF (according to ISGLS definition) were identified through multivariable analysis. Secondary end points were 30-day mortality and morbidity.

RESULTS

95 patients received PVE, of which 64 patients underwent major liver resection. PHLF occurred in 7 patients (11%). Calculated postoperative liver function was significantly lower in patients with PHLF than in patients without PHLF (67 vs. 109 μg/kg/h; p = 0.01). Other factors associated with PHLF by univariable analysis were age, future liver remnant, MELD score, ASA score, renal insufficiency and heart insufficiency. By multivariable analysis, future liver remnant was the only factor significantly associated with PHLF (p = 0.03). Mortality and morbidity rates were 4.7% and 29.7% respectively.

CONCLUSION

Future liver remnant is the only preoperative factor with a significant impact on PHLF. Assessment of preoperative liver function may additionally help identify patients at risk for PHLF.

Low Graft Attenuation at Unenhanced CT: Association with 1-Month Mortality or Graft Failure after Liver Transplantation

Purpose To investigate whether low graft attenuation at unenhanced computed tomography (CT) is associated with 1-month mortality or graft failure after liver transplant and determine its diagnostic performance. Materials and Methods Included were 663 recipients who underwent CT imaging within 7 days after liver transplant between December 2014 and August 2016. Initial poor function (IPF) was diagnosed by using a combination of laboratory values within 7 days after liver transplant and subdivided patients into primary and secondary IPF. At 1 month after the operation, mortality and graft failure or survival in recipients was categorized. Two radiologists who were blinded to clinical data retrospectively and independently evaluated graft attenuation on unenhanced CT images (high or isoattenuation, graft attenuation greater than or equal to that of spleen; low, graft attenuation less than that of spleen). The interobserver agreement was evaluated by using intraclass correlation coefficient and κ statics. Incidence of low graft attenuation between recipients with IPF and those with normal function was compared by using χ² test. The relationship between graft attenuation and outcome in primary and secondary IPF was evaluated by using log-rank test. Results Of 663 recipients, 114 had IPF (80 primary; 34 secondary). After 1 month, 11 had graft failure or died, whereas 652 survived. Low graft attenuation was more common in patients with IPF than in normal-function patients (P < .001). In the primary group (those without identifiable cause), 15 patients had low graft attenuation, which led to mortality or graft failure within 1 month in seven of those patients. No recipient with high or isoattenuation had 1-month mortality or graft failure (P < .001). The secondary group (those with identifiable cause) showed no significant association between graft attenuation and 1-month mortality and graft failure (P = .181). Values of low graft attenuation for 1-month mortality and graft failure in primary IPF were positive predictive value, 46.7%; negative predictive value, 100%; sensitivity, 100%; specificity, 89.0%; and accuracy, 90.0%. There was excellent interobserver agreement in the assessment of graft attenuation (intraclass correlation coefficient, 0.957; κ = 1.00). Conclusion Low graft attenuation can be associated with 1-month mortality or graft failure in liver graft recipients with primary IPF. ^© RSNA, 2017.

Clinical significance of lactate clearance for the development of early allograft dysfunction and short-term prognosis in deceased donor liver transplantation

This retrospective study evaluated lactate clearance (LC), measured at 6, 12, 18, and 24 hours after reperfusion, as a predictor of early allograft dysfunction (EAD) and short-term outcomes in patients receiving deceased donor liver transplantation. Of 181 transplant recipients, 44 (24.3%) developed EAD and had lower LCs than those who did not develop EAD. A receiver operating characteristic analysis showed that LC determined at 6 hours showed the highest area under curve value of 0.828 (95% confidence interval [CI]: 0.755-0.990) for predicting the development of EAD at a cutoff value of 25.8% with 76.7% sensitivity and 77.9% specificity. LC values that fell below the cutoff values were significantly associated with EAD in a multivariate analysis, with values at 6 hours having the highest adjusted odds ratio (11.891, 95% CI: 4.469-31.639). In-hospital and 6 month mortalities were higher in patients with LC values below the cutoffs compared with those above the cutoff values at each time point. Thus, LC calculated shortly after reperfusion of an allograft is significantly discriminative for the development of EAD and is associated with short-term prognosis after deceased donor liver transplantation.

Risk Factors for Post-Transplant Death in Donation after Circulatory Death Liver Transplantation

PURPOSE

In spite of the increasing success of liver transplantation, there remains inevitable risk of postoperative complications, re-operations, and even death. Risk factors that correlate with post-transplant death have not been fully identified.

MATERIALS AND METHODS

We performed a retrospective analysis of 65 adults that received donation after circulatory death liver transplantation. Binary logistic regression and Cox's proportional hazards regression were employed to identify risk factors that associate with postoperative death and the length of survival period.

RESULTS

Twenty-two recipients (33.8%) deceased during 392.3 ± 45.6 days. The higher preoperative Child-Pugh score (p = .007), prolonged postoperative ICU stay (p = .02), and more postoperative complications (p = .0005) were observed in deceased patients. Advanced pathological staging (p = .02) with more common nerve invasion (p = .03), lymph node invasion (p = .02), and para-tumor satellite lesion (p = .01) were found in deceased group. The higher pre-transplant Child-Pugh score was a risk factor for post-transplant death (OR = 4.38, p = .011), and was correlated with reduced post-transplant survival period (OR = 0.35, p = .009). Nerve invasion was also a risk factor for post-transplant death (OR = 13.85, p = .014), although it failed to affect survival period.

CONCLUSIONS

Our study emphasizes the impact of recipient's pre-transplant liver function as well as pre-transplant nerve invasion by recipient's liver cancer cells on postoperative outcome and survival period in patients receiving liver transplantation.

Primary non-function is frequently associated with fatty liver allografts and high mortality after re-transplantation

BACKGROUND & AIMS

The shortage of liver donations demands the use of suboptimal grafts with steatosis being a frequent finding. Although ≤30% macrovesicular steatosis is considered to be safe the risk for primary non-function (PNF) and outcome after re-transplantation (re-OLT) is unknown.

METHODS

Among 1205 orthotopic liver transplantations performed at our institution the frequency, survival and reason of re-OLT were evaluated. PNF (group A) cases and those with initial transplant function but subsequent need for re-OLT (group B) were analysed. Histopathology and clinical judgement determined the cause of PNF and included an assessment of hepatic steatosis. Additionally, survival of fatty liver allografts (group C) not requiring re-OLT was considered in Kaplan-Meier and multivariate regression analysis.

RESULTS

A total of 77 high urgency re-OLTs were identified and included 39 PNF cases. Nearly 70% of PNF cases were due to primary fatty liver allografts. The 3-month in-hospital mortality for PNF cases after re-OLT was 46% and the mean survival after re-OLT was 0.5 years as compared to 5.2 and 5.1 years for group B, C, respectively, (P<.008). In multivariate Cox regression analysis only hepatic steatosis was associated with an inferior survival (HR 4.272, P=.002). The MELD score, donor BMI, age, cold ischaemic time, ICU stay, serum sodium and transaminases did not influence overall survival.

CONCLUSIONS

Our study highlights fatty liver allografts to be a major cause for PNF with excessive mortality after re-transplantation. The findings demand the development of new methods to predict risk for PNF of fatty liver allografts.

Linezolid in liver failure: exploring the value of the maximal liver function capacity (LiMAx) test in a pharmacokinetic pilot study

Patients in the intensive care unit frequently require antibiotic treatment. Liver impairment poses substantial challenges for dose selection in these patients. The aim of the present pilot study was to assess the novel maximal liver function capacity (LiMAx test) in comparison with conventional liver function markers as covariates of drug clearance in liver failure using linezolid as a model drug. A total of 28 patients with different degrees of liver failure were recruited. LiMAx test as well as plasma, dialysate and urine sampling were performed under linezolid steady-state therapy (600 mg twice daily). NONMEM^® was used for a pharmacometric analysis in which the different clearance routes of linezolid were elucidated. Linezolid pharmacokinetics was highly variable in patients with liver failure. The LiMAx score displayed the strongest association with non-renal clearance (CL_non-renal) [ = 4.46∙(body weight/57.9) ^0.75∙(LiMAx/221.5)^0.388 L/h], which reduced interindividual variability in CL_non-renal from 46.6% to 33.6%, thereby being superior to other common markers of liver function (international normalised ratio, gamma-glutaryl transferase, bilirubin, thrombocytes, alanine aminotransferase, aspartate aminotransferase). For LiMAx < 100 µg/kg/h, 64% of linezolid trough concentrations were above the recommended trough concentration of 8 mg/L, indicating the necessity of therapeutic drug monitoring in these patients. This is the first pilot application of the LiMAx test in a pharmacokinetic (PK) study demonstrating its potential to explain PK variability in linezolid clearance. Further studies with a larger patient collective and further drugs are highly warranted to guide dosing in patients with severe liver impairment.

Potential Roles for C1 Inhibitor in Transplantation

Complement is a major contributor to inflammation and graft injury. This system is especially important in ischemia-reperfusion injury/delayed graft function as well as in acute and chronic antibody-mediated rejection (AMR). The latter is increasingly recognized as a major cause of late graft loss, for which we have few effective therapies. C1 inhibitor (C1-INH) regulates several pathways which contribute to both acute and chronic graft injuries. However, C1-INH spares the alternative pathway and the membrane attack complex (C5–9) so innate antibacterial defenses remain intact. Plasma-derived C1-INH has been used to treat hereditary angioedema for more than 30 years with excellent safety. Studies with C1-INH in transplant recipients are limited, but have not revealed any unique toxicity or serious adverse events attributed to the protein. Extensive data from animal and ex vivo models suggest that C1-INH ameliorates ischemia-reperfusion injury. Initial clinical studies suggest this effect may allow transplantation of donor organs which are now discarded because the risk of primary graft dysfunction is considered too great. Although the incidence of severe early AMR is declining, accumulating evidence strongly suggests that complement is an important mediator of chronic AMR, a major cause of late graft loss. Thus, C1-INH may also be helpful in preserving function of established grafts. Early clinical studies in transplantation suggest significant beneficial effects of C1-INH with minimal toxicity. Recent results encourage continued investigation of this already-available therapeutic agent.

Correlation between plasma endothelin-1 levels and severity of septic liver failure quantified by maximal liver function capacity (LiMAx test). A prospective study

Aim

To investigate the relationship between the degree of liver dysfunction, quantified by maximal liver function capacity (LiMAx test) and endothelin-1, TNF-α and IL-6 in septic surgical patients.

Methods

28 septic patients (8 female, 20 male, age range 35–80y) were prospectively investigated on a surgical intensive care unit. Liver function, defined by LiMAx test, and measurements of plasma levels of endothelin-1, TNF-α and IL-6 were carried out within the first 24 hours after onset of septic symptoms, followed by day 2, 5 and 10. Patients were divided into 2 groups (group A: LiMAx ≥100 μg/kg/h, moderate liver dysfunction; group B: LiMAx <100 μg/kg/h, severe liver dysfunction) for analysis and investigated regarding the correlation between endothelin-1 and the severity of liver failure, quantified by LiMAx test.

Results

Group B showed significant higher results for endothelin-1 than patients in group A (P = 0.01, d5; 0.02, d10). For TNF-α, group B revealed higher results than group A, with a significant difference on day 10 (P = 0.005). IL-6 showed a non-significant trend to higher results in group B. The Spearman's rank correlation coefficient revealed a significant correlation between LiMAx and endothelin-1 (-0.434; P <0.001), TNF-α (-0.515; P <0.001) and IL-6 (-0.590; P <0.001).

Conclusions

Sepsis-related hepatic dysfunction is associated with elevated plasma levels of endothelin-1, TNF-α and IL-6. Low LiMAx results combined with increased endothelin-1 and TNF-α and a favourable correlation between LiMAx and cytokine values support the findings of a crucial role of Endothelin-1 and TNF-α in development of septic liver failure.

The impact of directly acting antivirals on the enzymatic liver function of liver transplant recipients with recurrent hepatitis C

BACKGROUND

The new directly acting antivirals (DAAs) enable all-oral interferon-free treatment of chronic hepatitis C virus (HCV) infection. We here investigated the effect of DAAs on the enzymatic liver function of liver transplant recipients with recurrent hepatitis C.

METHODS

Twenty-one patients with elevated liver enzymes or advanced fibrosis/compensated cirrhosis caused by recurrent HCV were treated with sofosbuvir either in combination with simeprevir, or in combination with ribavirin or daclatasvir with or without ribavirin for 12 weeks. Biochemical parameters, tacrolimus trough levels, and the maximal liver function capacity (LiMAx) were measured monthly during the treatment and 12 weeks after the end of treatment.

RESULTS

All patients achieved sustained virological response 12 weeks after the end of the treatment. The transaminases and cholestasis parameters normalized until week 8 of treatment. The mean LiMAx (normal ranges >315 μg/kg/h) increased from 344±142 μg/kg/h before treatment to 458±170 μg/kg/h (P<.0001) at the 12-week follow-up. In parallel, the tacrolimus trough level to dose ratio decreased from 4.68 down to 2.72 (P=.0004).

CONCLUSION

Antiviral treatment with DAAs enabled sustained elimination of recurrent HCV in liver transplant recipients and was associated with a significant improvement of the enzymatic liver function.

Primary graft dysfunction of the liver: definitions, diagnostic criteria and risk factors

Primary graft dysfunction is a multifactorial syndrome with great impact on liver transplantation outcomes. This review article was based on studies published between January 1980 and June 2015 and retrieved from PubMed database using the following search terms: "primary graft dysfunction", "early allograft dysfunction", "primary non-function" and "liver transplantation". Graft dysfunction describes different grades of graft ischemia-reperfusion injury and can manifest as early allograft dysfunction or primary graft non-function, its most severe form. Donor-, surgery- and recipient-related factors have been associated with this syndrome. Primary graft dysfunction definition, diagnostic criteria and risk factors differ between studies. RESUMO A disfunção primária do enxerto hepático é uma síndrome multifatorial com grande impacto no resultado do transplante de fígado. Foi realizada uma ampla revisão da literatura, consultando a base de dados PubMed, em busca de estudos publicados entre janeiro de 1980 e junho de 2015. Os termos descritivos utilizados foram: "primary graft dysfunction", "early allograft dysfunction", "primary non-function" e "liver transplantation". A disfunção traduz graus diferentes da lesão de isquemia e reperfusão do órgão, e pode se manifestar como disfunção precoce ou, na forma mais grave, pelo não funcionamento primário do enxerto. Fatores relacionados ao doador, ao transplante e ao receptor contribuem para essa síndrome. Existem definições diferentes na literatura quanto ao diagnóstico e aos fatores de risco associados à disfunção primária.

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.

Conditioning With Sevoflurane in Liver Transplantation: Results of a Multicenter Randomized Controlled Trial

BACKGROUND

During times of organ scarcity and extended use of liver grafts, protective strategies in transplantation are gaining importance. We demonstrated in the past that volatile anesthetics such as sevoflurane attenuate ischemia-reperfusion injury during liver resection. In this randomized study, we examined if volatile anesthetics have an effect on acute graft injury and clinical outcomes after liver transplantation.

METHODS

Cadaveric liver transplant recipients were enrolled from January 2009 to September 2012 at 3 University Centers (Zurich/Sao Paulo/Ghent). Recipients were randomly assigned to propofol (control group) or sevoflurane anesthesia. Postoperative peak of aspartate transaminase was defined as primary endpoint, secondary endpoints were early allograft dysfunction, in-hospital complications, intensive care unit, and hospital stay.

RESULTS

Ninety-eight recipients were randomized to propofol (n = 48) or sevoflurane (n = 50). Median peak aspartate transaminase after transplantation was 925 (interquartile range, 512-3274) in the propofol and 1097 (interquartile range, 540-2633) in the sevoflurane group. In the propofol arm, 11 patients (23%) experienced early allograft dysfunction, 7 (14%) in the sevoflurane one (odds ratio, 0.64 (0.20 to 2.02, P = 0.45). There were 4 mortalities (8.3%) in the propofol and 2 (4.0%) in the sevoflurane group. Overall and major complication rates were not different. An effect on clinical outcomes was observed favoring the sevoflurane group (less severe complications), but without significance.

CONCLUSIONS

This first multicenter trial comparing propofol with sevoflurane anesthesia in liver transplantation shows no difference in biochemical markers of acute organ injury and clinical outcomes between the 2 regimens. Sevoflurane has no significant added beneficial effect on ischemia-reperfusion injury compared to propofol.

(13) C Breath Tests Are Feasible in Patients With Extracorporeal Membrane Oxygenation Devices

Temporary extracorporeal membrane oxygenation (ECMO) has been established as an essential part of therapy in patients with pulmonary or cardiac failure. As physiological gaseous exchange is artificially altered in this patient group, it is debatable whether a (13) C-breath test can be carried out. In this proof of technical feasibility report, we assess the viability of the (13) C-breath test LiMAx (maximum liver function capacity) in patients on ECMO therapy. All breath probes for the test device were obtained directly via the membrane oxygenator. Data of four patients receiving liver function assessment with the (13) C-breath test LiMAx while having ECMO therapy were analyzed. All results were compared with validated scenarios of the testing procedures. The LiMAx test could successfully be carried out in every case without changing ECMO settings. Clinical course of the patients ranging from multiorgan failure to no sign of liver insufficiency was in accordance with the results of the LiMAx liver function test. The (13) C-breath test is technically feasible in the context of ECMO. Further evaluation of (13) C-breath test in general would be worthwhile. The LiMAx test as a (13) C-breath test accessing liver function might be of particular predictive interest if patients with ECMO therapy develop multiorgan failure.

Risk factors of metabolic disorders after liver transplantation: an analysis of data from fasted patients

BACKGROUND

Metabolic disorders are common complications after orthotopic liver transplantation (OLT) and may lead to increased morbidity and mortality.

METHODS

Fasting glucose and lipid metabolism, and body weight of 81 patients undergoing primary OLT were prospectively analyzed. Patients were investigated preoperatively, on postoperative days 1, 3, 5, 10, 14, 28 as well as 6 months and 1 year after OLT. Data of nonfasted patients were excluded from the analysis. Standardized definitions and classifications for diabetes mellitus (DM), body mass index (BMI), and dyslipidemia were used.

RESULTS

Prevalence of new-onset diabetes after transplantation was 9.3%, and obesity was its only independent risk factor (odds ratio [OR], 16.5). Preoperative impaired glucose homeostasis (OR, 10.8) and initial poor graft function (OR, 6.89) were independent risk factors for postoperative DM. Maximum prevalence of hypertriglyceridemia and hypercholesterolemia was found on postoperative day 10 and 6 months post-OLT, respectively. Risk factors for hypercholesterolemia at 1 year were patient age (OR, 1.17) and postoperative renal dysfunction (OR, 16.33). Higher preoperative BMI was a risk factor for postoperative hypertriglyceridemia (OR, 1.17). Overall body weight and BMI significantly decreased over 1 year (P < 0.05). Prevalence of obesity was 22.2% before and 20.9% after OLT.

CONCLUSION

For the first time, initial poor graft function was identified as a risk factor for post-OLT DM. By ruling out any exogenous factors influencing metabolism, we believe we were able to show the true prevalence of metabolic disorders and therefore provided a valuable contribution to the identification of potential risk factors.

Noninvasive diagnosis of chemotherapy induced liver injury by LiMAx test--two case reports and a review of the literature

Background

Chemotherapy-induced liver injury is a well-known phenomenon after neoadjuvant therapy of liver metastasis and contributes to postoperative morbidity and mortality. Still there is no suitable test available to reliably determine functional impairment and hepatic regeneration after chemotherapy.

Case presentation

We report two cases of caucasian patients who underwent repeated liver function assessments using LiMAx (maximum liver function capacity), Indocyanine plasma disappearance rate and biochemical liver function parameters in the course of adjuvant oxaliplatin-based chemotherapy.

Both patients yielded a decrease from their initial liver function determined by LiMAx. Liver regeneration assessed functional recovery within 4 weeks in case of mild functional impairment after cessation of chemotherapy or within 8 weeks in case of major functional deterioration. Indocyanine plasma disappearance rate and biochemical parameters remained stable or without a clear trend in case of minor functional impairment. This is the first report using a dynamic liver function test to evaluate the impact and recovery from chemotherapy associated liver injury.

Conclusions

The LiMAx test might be a sensitive tool to diagnose mild functional impairment after chemotherapy when standard liver function tests have remained within normal ranges and might be capable to assess the course of regeneration after chemotherapy. This could be useful to optimize individual chemotherapy-free interval before liver surgery can be carried out safely.

Portal vein embolization with plug/coils improves hepatectomy outcome

BACKGROUND

Portal vein embolization (PVE) has become the standard of care before extended hepatectomy. Various PVE methods using different embolization materials have been described. In this study, we compared PVE with polyvinyl alcohol particles alone (PVA only) versus PVA with plug or coils (PVA + plug/coils).

MATERIALS AND METHODS

Patients undergoing PVE before hepatectomy were included. PVA alone was used until December 2013, thereafter plug or coils were placed in addition. The volume of left lateral liver lobe (LLL), clinical parameters, and liver function tests were measured before PVE and resection.

RESULTS

A total of 43 patients were recruited into the PVA only group and 42 were recruited into the PVA + plug/coils group. There were no major differences between groups except significantly higher total bilirubin level before PVE in the PVA only group, which improved before hepatectomy. Mean LLL volume increased by 25.7% after PVE in the PVA only group and by 44% in the PVA + plug/coils group (P < 0.001). Recanalization was significantly less common in the PVA + plug/coils group. In multivariate regression, initial LLL volume and use of plug or coils were the only parameters influencing LLL volume increase. The postoperative liver failure rate was significantly reduced in PVA + plug/coils group (P = <0.001).

CONCLUSIONS

PVE using PVA particles together with plug or coils is a safe and efficient method to increase future liver remnant volume. The additional central embolization with plug or coils led to an increased hypertrophy, due to lower recanalization rates, and subsequently decreased incidence of postoperative liver failure. No additional procedure-specific complications were observed in this series.

Enzymatic liver function capacity correlates with disease severity of patients with liver cirrhosis: a study with the LiMAx test

BACKGROUND

Assessment and quantification of actual liver function is crucial in patients with chronic liver disease to monitor disease progression and predict individual prognosis. Mathematical models, such as model for end-stage liver disease, are used for risk stratification of patients with chronic liver disease but do not include parameters that reflect the actual functional state of the liver.

AIM

We aimed to evaluate the potential of a (13)C-based liver function test as a stratification tool by comparison with other liver function tests and clinical parameters in a large sample of healthy controls and cirrhotic patients.

METHODS

We applied maximum liver function capacity (LiMAx) to evaluate actual liver function in 347 patients with cirrhosis and in 86 controls.

RESULTS

LiMAx showed strong negative correlation with Child-Pugh Score (r = -0.707; p < 0.001), MELD (r = -0.686; p < 0.001) and liver function tests. LiMAx was lower in patients with liver cirrhosis compared to healthy controls [99 (57-160) µg/kg/h vs. 412 (365-479) µg/kg/h, p < 0.001] and differed among Child-Pugh classes [a: 181 (144-227) µg/kg/h, b: 96 (62-132) µg/kg/h and c: 52 (37-81) µg/kg/h; p < 0.001]. When stratified patients according to disease severity, LiMAx results were not different between cirrhotic patients and cirrhotic patients with transjugular intrahepatic portosystemic shunt.

CONCLUSIONS

LiMAx appears to provide reliable information on remnant enzymatic liver function in chronic liver disease and allows graduation of disease severity.

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.

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.

A proposal to grade the severity of early allograft dysfunction after liver transplantation

Objective:

To propose a grading system for early hepatic graft dysfunction.

Methods:

A retrospective study from a single transplant center. Recipients of liver transplants from deceased donors, transplanted under the MELD system were included. Early graft dysfunction was defined by Olthoff criteria. Multiple cut-off points of post-transplant laboratory tests were used to create a grading system for early graft dysfunction. The primary outcome was 6-months grafts survival.

Results:

The peak of aminotransferases during the first postoperative week correlated with graft loss. The recipients were divided into mild (aminotransferase peak >2,000IU/mL, but <3,000IU/mL); moderate (aminotransferase peak >3,000IU/mL); and severe (aminotransferase peak >3,000IU/mL + International Normalized Ratio ≥1.6 and/or bilirubin ≥ 10mg/dL in the 7^th postoperative day) early allograft dysfunction. Moderate and severe early dysfunctions were independent risk factors for graft loss. Patients with mild early dysfunction presented with graft and patient survival comparable to those without graft dysfunction. However, those with moderate early graft dysfunction showed worse graft survival than those who had no graft dysfunction. Patients with severe early dysfunction had graft and patient survival rates worse than those of any other groups.

Conclusion:

Early graft dysfunction can be graded by a simple and reliable criteria based on the peak of aminotransferases during the first postoperative week. The severity of the early graft dysfunction is an independent risk factor for allograft loss. Patients with moderate early dysfunction showed worsening of graft survival. Recipients with severe dysfunction had a significantly worse prognosis for graft and patient survival.

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.

Assessment of hepatic detoxification activity: proposal of an improved variant of the (13)c-methacetin breath test

Breath tests based on the administration of a (13)C-labeled drug and subsequent monitoring of (13)CO2 in the breath (quantified as DOB - delta over baseline) liberated from the drug during hepatic CPY-dependent detoxification are important tools in liver function diagnostics. The capability of such breath tests to reliably indicate hepatic CYP performance is limited by the fact that (13)CO2 is not exclusively exhaled but also exchanged with other compartments of the body. In order to assess this bias caused by variations of individual systemic CO2 kinetics we administered intravenously the test drug (13)C-methacetin to 25 clinically liver-healthy individuals and monitored progress curves of DOB and the plasma concentration of (13)C-methacetin. Applying compartment modelling we estimated for each individual a set of kinetic parameters characterizing the time-dependent exchange of the drug and of CO2 with the liver and non-hepatic body compartments. This analysis revealed that individual variations in the kinetics of CO2 may account for up to 30% deviation of DOB curve parameters from their mean at otherwise identical (13)C-methacetin metabolization rates. In order to correct for this bias we introduced a novel detoxification score which ideally should be assessed from the DOB curve of a 2-step test ("2DOB") which is initialized with the injection of a standard dose of (13)C-labeled bicarbonate (in order to provide information on the actual CO2 status of the individual) followed by injection of the (13)C-labeled test drug (the common procedure). Computer simulations suggest that the predictive power of the proposed 2DOB breath test to reliably quantity the CYP-specific hepatic detoxification activity should be significantly higher compared to the conventional breath test.

Predicting early allograft failure and mortality after liver transplantation: the role of the postoperative model for end-stage liver disease score

Early allograft dysfunction (EAD) is a serious complication after liver transplantation (LT). There is no uniform definition of EAD, and most definitions are based on arbitrary laboratory values. The aim of this study was to devise a definition of EAD that maximizes the predictive power for early death and graft failure. In this single-center, retrospective study, the ability of the international normalized ratio (INR), total bilirubin, aspartate aminotransferase (AST), physiological Model for End-Stage Liver Disease (MELD) score, and serum albumin levels within 7 days after LT to predict 90-day mortality or graft loss was compared with 2 previously used definitions of EAD: (1) peak total bilirubin level >10 mg/dL on days 2 to 7 and (2) either a total bilirubin level >10 mg/dL or an INR >1.6 on day 7 or an AST or alanine aminotransferase level >2000 IU/L within the first 7 days. Of 572 enrolled LT patients 38 died or required retransplantation within 90 days. Peak INR, total bilirubin level, AST levels, and MELD scores were predictors of 90-day graft failure. MELD score on postoperative day 5 was the best predictor with an area under the curve of the receiver operating characteristic curve of 0.812 (95% CI: 0.739-0.886, P < 0.001). The best cutoff of MELD score on day 5 for predicting 90-day mortality or graft loss was 18.9. A MELD score >18.9 on postoperative day 5 was a better predictor than any other laboratory value or definition of EAD. This study has demonstrated that the MELD score can be a useful tool not only for pretransplant graft allocation but also for postoperative risk stratification.