Early diagnosis of primary nonfunction and indication for reoperation after liver transplantation

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.

L-Alanyl-Glutamine Attenuates Oxidative Stress in Liver Transplantation Patients

BACKGROUND

Ischemia/reperfusion injury during liver transplantation can cause severe damage to the graft. The objective of this randomized, double-blind study was to evaluate the possible protective effects of L-alanyl-glutamine on the liver graft.

METHODS

The sample included 33 patients from a liver transplantation service in Northeastern Brazil. Before cold ischemia, the patients received 50 g of L-alanyl-glutamine (treatment group) or saline (control group) through the portal vein. The graft was biopsied at the time of recovery, at the beginning of warm ischemia, and at the end of transplantation to determine malondialdehyde (MDA), heat-shock protein (Hsp)70, nuclear factor kappa-beta (NFkB), superoxide dismutase (SOD), and reduced glutathione (GSH) levels.

RESULTS

The blood parameters were similar in the two groups. In the treatment group, MDA did not increase at the beginning of cold ischemia and decreased at the end of transplantation. This phenomenon was not observed in the control group. GSH, SOD, Hsp70, and NFkB levels were similar in the two groups.

CONCLUSIONS

Our findings suggest that preconditioning with L-alanyl-glutamine attenuates the effects of ischemia/reperfusion-related oxidative stress and reduces lipid peroxidation in the grafts of liver transplantation patients.

Functional Liver Recovery After Bariatric Surgery--a Prospective Cohort Study with the LiMAx Test

BACKGROUND

Bariatric surgery provides long-term weight loss and improvement of obesity-associated diseases such as nonalcoholic steatohepatitis (NASH). Histologic improvement of NASH has been reported in some studies after bariatric surgery. This study was designed to assess the liver function in obese patients as well as its recovery after bariatric surgery with a noninvasive test method.

METHODS

In a prospective cohort study from October 2011 to May 2014, morbidly obese individuals receiving bariatric surgery were investigated for functional liver recovery (n = 34). Liver function was determined by the LiMAx test (enzymatic capacity of cytochrome P450 1A2) preoperatively, 6 and 12 months postoperatively. Liver biopsy specimens were obtained from 18 participants and classified according to the nonalcoholic fatty liver disease (NAFLD) activity score (NAS).

RESULTS

The mean age of participants was 44 years, and the mean body mass index (BMI) was 52 kg/m(2). The mean percent excess BMI loss (%EBMIL) was 53 % after 6 months and 68 % after 1 year. Mean liver function capacity increased significantly from 255 μg/kg/h preoperative to 324 μg/kg/h after 6 months and 342 μg/kg/h after 12 months. A negative correlation was observed between %EBMIL and alteration of liver function capacity in the first 6 months. Finally, the median NAS showed a negative correlation with liver function capacity.

CONCLUSIONS

Bariatric surgery leads to a significant functional recovery of the liver. An initial marked weight loss may negatively influence functional liver recovery.

(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.

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.

Low serum factor V level: early predictor of allograft failure and death following liver transplantation

PURPOSE

According to the current criteria, the diagnosis of early allograft dysfunction usually cannot be established before the end of the first week after liver transplantation. Thus, early predictive tests for detecting allograft dysfunction are still warranted to prevent allograft failure. This study was undertaken to assess the role of low serum factor V activity as an early prognostic factor (postoperative day 2) after liver transplantation.

METHODS

A retrospective review of all consecutive adult patients who underwent first orthotopic whole-graft liver transplant at our institution between March 2002 and June 2011 was undertaken. Primary endpoint was graft failure within 90 days after transplantation.

RESULTS

Of all 105 patients analyzed in this study, 39 (37.1 %) were female and 66 (62.9 %) were male. Mean age was 52.7 ± 11.7 years, and median follow-up period was 2474 ± 164 days. There were overall 33 (31.4 %) deaths, 13 of those occurring on the first 90 post-transplant days. Multivariate analysis demonstrated that serum factor V lower than 41.5 % and female gender had a negative impact not only on allograft failure/death within 90 days after transplantation (RR = 5.30, CI = 1.40-20.2, p = 0.015 and RR = 5.23, CI = 1.53-21.33, p = 0.008) but also on overall mortality. For prediction of allograft failure/death occurring during the first 3 months, serum factor V level of 41.5 % or lower exhibited a specificity of 87.9 %, a sensitivity of 42.9 %, an accuracy of 81.9 %, a positive predictive value of 35.3 %, and a negative predictive value of 90.9 %.

CONCLUSIONS

Assessment of serum factor V levels on postoperative day 2 might be a promising prognostic tool for early prediction of inferior outcomes after liver transplantation.

A score model for the continuous grading of early allograft dysfunction severity

Early allograft dysfunction (EAD) dramatically influences graft and patient outcomes. A lack of consensus on an EAD definition hinders comparisons of liver transplant outcomes and management of recipients among and within centers. We sought to develop a model for the quantitative assessment of early allograft function [Model for Early Allograft Function Scoring (MEAF)] after transplantation. A retrospective study including 1026 consecutive liver transplants was performed for MEAF score development. Multivariate data analysis was used to select a small number of postoperative variables that adequately describe EAD. Then, the distribution of these variables was mathematically modeled to assign a score for each actual variable value. A model, based on easily obtainable clinical parameters (ie, alanine aminotransferase, international normalized ratio, and bilirubin) and scoring liver function from 0 to 10, was built. The MEAF score showed a significant association with patient and graft survival at 3-, 6- and 12-month follow-ups. Hepatic steatosis and age for donors; cold/warm ischemia times and postreperfusion syndrome for surgery; and intensive care unit and hospital stays, Model for End-Stage Liver Disease and Child-Pugh scores, body mass index, and fresh frozen plasma transfusions for recipients were factors associated significantly with EAD. The model was satisfactorily validated by its application to an independent set of 200 patients who underwent liver transplantation at a different center. In conclusion, a model for the quantitative assessment of EAD severity has been developed and validated for the first time. The MEAF provides a more accurate graft function assessment than current categorical classifications and may help clinicians to make early enough decisions on retransplantation benefits. Furthermore, the MEAF score is a predictor of recipient and graft survival. The standardization of the criteria used to define EAD may allow reliable comparisons of recipients' treatments and transplant outcomes among and within centers.

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.

Prognostic value of enzymatic liver function for the estimation of short-term survival of liver transplant candidates: a prospective study with the LiMAx test

LiMAx has been recently proposed as a new quantitative liver function test. Thus, we aimed to evaluate the diagnostic ability of LiMAx to assess short-term survival in liver transplant candidates and compare its performance to the model for end-stage liver disease (MELD) and indocyanine green plasma disappearance rate (ICG-PDR). Liver function of 167 chronic liver failure patients without hepatocellular carcinoma was prospectively investigated when they were evaluated for liver transplantation. Primary study endpoints were liver-related death within 6 months of follow-up. Within 6 months of follow-up, 18 patients died and 36 underwent liver transplantation. Median LiMAx results on evaluation day were significantly lower in patients who died (99 μg/kg/h vs. 55 μg/kg/h; P = 0.024), while median ICG-PDR results did not differ within both groups (4.4%/min vs. 3.5%/min; P = 0.159). LiMAx showed a higher negative predictive value (NPV: 0.93) as compared with ICG-PDR (NPV: 0.90) and the MELD (NPV: 0.91) in predicting risk of death within 6 months. In conclusion, LiMAx provides good prognostic information of liver transplant candidates. In particular, patients who are not at risk of death can be identified reliably by measuring actual enzymatic liver function capacity.

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.

Effect of delayed CNI-based immunosuppression with Advagraf® on liver function after MELD-based liver transplantation [IMUTECT]

BACKGROUND

MELD-based allocation for liver transplantation follows the "sickest-patient-first" strategy. The latter patients present with both, decreased immune competence and poor kidney function which is further impaired by immunosuppressants.

METHODS/DESIGN

In this prospective observational study, 50 patients with de novo low-dose standard Advagraf®-based immunosuppression consisting of Advagraf®, Mycophenolat-mofetil and Corticosteroids after liver transplantation will be evaluated. Advagraf® trough levels of 7-10 μg/l will be reached at the end of the first postoperative week. Immunostatus, infectious complications, graft and kidney function are compared between patients with a pretransplant calculated MELD-score of ≤20 and >20. Each group comprises of 25 consecutive patients. Prior to liver transplantation and on the postoperative days 1, 3 and 7, the patients' graft function (LiMAx test) will be evaluated. On the postoperative days 3, 5 and 7 the patients' immune status will be evaluated by the measurement of their monocytic HLA-DR status.Infectious complications (CMV-reactivation, wound infection, urinary tract infection, and pneumonia), graft- and kidney function will be analysed on day 0, within the first week, and 1, 3, 6, 9 and 12 months after liver transplantation.

DISCUSSION

This study was designed to assess the effect of a standard low-dose Calcineurin inhibitor-based immunosuppression regime with Advagraf® on the rate of infectious complications, graft and renal function after liver transplantation.

TRIAL REGISTRATION

The trial is registered at "Clinical Trials" (http://www.clinicaltrials.gov), NCT01781195.

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.

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.

A rapid and accurate new bedside test to assess maximal liver function: a case report

Background

In liver surgery, appropriate preoperative evaluation and preparation of the patient is of cardinal importance. The up-to-date, preoperative prediction of residual liver function has thus far been limited. As post-hepatectomy liver failure is a major cause of mortality, a new and simple bedside test (LiMAx) has been developed to predict postoperative liver function in conjunction with preoperative volumetric analysis of the liver.

Case presentation

A 45-year-old patient presented with a cecal carcinoma and a large synchronous liver metastasis for major liver surgery. Liver function was determined by the LiMAx-test for the enzymatic capacity of cytochrome P450 1A2, which is ubiquitously and solely active in the liver. A solution of 2 mg/kg body weight ¹³C-labeled methacetin was injected as a bolus into an intravenous catheter and, thereafter, was metabolized into acetaminophen and ¹³CO2 and pulmonarily exhaled. The analysis of the ¹³CO2/¹²CO2 ratio was performed using online breath sampling over a period of maximally 60 minutes. Based on this test, a value of more than 315 μg/kg/h represents normal liver function. A laparoscopic right hemihepatectomy was planned during virtual resection with a residual liver volume of 48% and a preoperative anticipated residual LiMAx of 301 μg/kg/h. After successful resection, the initial postoperative LiMAx value was 316 μg/kg/h, indicating good liver function and a correct prediction of the outcome.

Conclusion

In the presented patient, residual liver function could be accurately predicted preoperatively using a combination of the new LiMax test with CT-volumetry. This test might significantly improve preoperative evaluation and postoperative outcomes in liver surgery.

Function and volume recovery after partial hepatectomy: influence of preoperative liver function, residual liver volume, and obesity

BACKGROUND

The regenerative capacity of the liver is an essential pre-condition for the successful application of partial hepatectomy. However, the actual kinetics of functional recovery remains unspecified and no adequate tool for its clinical monitoring has yet been available.

METHODS

Eighty-five patients receiving major hepatectomy were investigated from the preoperative evaluation until 12 weeks after surgery. Liver function was determined by the LiMAx test for the enzymatic capacity of cytochrome P450 1A2. Liver volume was determined by volumetric analysis of repeated computer tomography scans. Functional and volume recovery were compared during follow-up.

RESULTS

Major hepatectomy decreased liver function capacity to 35.7 ± 13.8% of preoperative function. It was shown that functional recovery already reaches 77.2 ± 33.5% of preoperative values within 10 days. The actual kinetics were dependent from the type and extent of hepatectomy. Complete functional restoration was achieved within 12 weeks, while liver volume still remained at 73.2 ± 14.8% of preoperative. A constant but interindividually variable correlation between function and volume was observed at all points in time.

CONCLUSION

Partial hepatectomy leads to fast and complete functional recovery, while volume recovery is delayed and remains often incomplete. The functional recovery is mainly influenced by the preoperative liver function, the residual liver volume, and by obesity.

Urinary ammonia excretion increases acutely during living donor liver transplantation

INTRODUCTION

Arterial ammonia concentrations increase acutely during the anhepatic phase of a liver transplantation (LTx) and return to baseline within 1 h after reperfusion of a functioning liver graft. So far, this return to baseline has solely been attributed to hepatic ammonia clearance. No data exist on the potential contribution of altered renal ammonia handling to peritransplantation ammonia homoeostasis.

AIM

The present study investigated the consequences of a hepatectomy and subsequent implantation of a partial liver graft on arterial ammonia concentrations and urinary ammonia excretion during a living donor liver transplantation (LDLTx).

METHODS

Patients with end-stage liver disease undergoing LDLTx were selected. Samples of arterial blood and urine were taken before, during and 2 h after the anhepatic phase. Differences were tested using Wilcoxon's test. Results are given as median and range.

RESULTS

Eleven adult patients undergoing an LDLTx were included. Before hepatectomy, arterial ammonia concentrations were 89 μM (40-156 μM), increasing to 146 μM (102-229 μM) (P<0.001) during the anhepatic phase and returning to 79 μM (46-111 μM) (P<0.01) after reperfusion. Urinary ammonia excretion was initially 1.06 mmol/h (0.02-6.00 mmol/h), increasing to 3.81 mmol/h (0.32-12.55 mmol/h) (P=0.004) during the anhepatic phase and further increasing to 4.00 mmol/h (0.79-9.51 mmol/h) (P=0.013) after reperfusion.

CONCLUSION

The kidney significantly increased urinary ammonia excretion during the anhepatic phase, which was sustained after reperfusion, contributing to the rapid decrease of ammonia concentrations. Accordingly, the plasma ammonia concentrations measured directly after LTx cannot simply be used as a read-out of initial liver graft function.

Long-term survival after 67 hours of anhepatic state due to primary liver allograft nonfunction

Primary liver allograft nonfunction immediately after transplantation poses a life-threatening situation for the recipient. Emergency retransplantation may not be immediately possible due to organ unavailability. Total hepatectomy with temporary portacaval shunt has been described as a bridge to retransplantation when the presence of the graft appears to be harming the recipient. Case reports of retransplantation after total hepatectomy with anhepatic times greater than 48 hours routinely describe poor outcomes. We present a case with excellent patient outcome after 95 hours of clinical anhepatic state, including 67 hours of anatomical anhepatic time, because of primary liver allograft nonfunction. This case report documents the longest anhepatic time with subsequent successful transplant to date.

Initial liver graft function is a reliable predictor of tacrolimus trough levels during the first post-transplant week

The narrow therapeutic range of tacrolimus requires careful management after liver transplantation (LT). The aim of this study was to investigate the influence of graft function on tacrolimus trough levels during the first post-transplant week. Ninety-three patients receiving deceased-donor LT were observed in a prospective observational study. Graft function was determined by the new LiMAx test (maximal liver function capacity). Significant correlations between LiMAx readouts and consecutive tacrolimus levels, up to r = -0.529 (p < 0.0001), were determined throughout the observed period of time. Patients with initially poor graft function revealed higher trough levels (n = 24; 20.1 ± 11.6ng/mL) in comparison with fair (n = 40; 13.7 ± 7.8 ng/mL) and good function (n = 29; 9.5 ± 4.4ng/mL; p < 0.0001) already at the second post-transplant day. Toxic levels could be predicted with an area under receiver operating characteristic analysis AUROC=0.751 (p = 0.001) with high sensitivity and specificity. Insufficient levels could be predicted with AUROC=0.800 (p = 0.003). In conclusion, initial graft function is a major factor influencing the pharmacokinetics of tacrolimus and can be validly determined by the LiMAx test. Thus, recipients with poor functioning grafts are prone of developing toxic levels within the first week after LT, whereas patients with good functioning grafts frequently develop insufficient levels with the current immunosuppressive protocols.