Use and validation of selection criteria for liver transplantation in acute liver failure

Acute liver failure in children-Is living donor liver transplantation justified?

OBJECTIVES

Living donor liver transplantation (LDLT) in patients with acute liver failure (ALF) has become an acceptable alternative to transplantation from deceased donors (DDLT). The aim of this study was to analyze outcomes of LDLT in pediatric patients with ALF based on our center's experience.

MATERIAL AND METHODS

We enrolled 63 children (at our institution) with ALF who underwent liver transplantation between 1997 and 2016. Among them 24 (38%) underwent a LDLT and 39 (62%) received a DDLT. Retrospectively analyzed patient clinical data included: time lapse between qualification for transplantation and transplant surgery, graft characteristics, postoperative complications, long-term results post-transplantation, and living donor morbidity. Overall, we have made a comparison of clinical results between LDLT and DDLT groups.

RESULTS

Follow-up periods ranged from 12 to 182 months (median 109 months) for LDLT patients and 12 to 183 months (median 72 months) for DDLT patients. The median waiting time for a transplant was shorter in LDLT group than in DDLT group. There was not a single case of primary non-function (PNF) in the LDLT group and 20 out of 24 patients (83.3%) had good early graft function; 3 patients (12.5%) in the LDLT group died within 2 months of transplantation but there was no late mortality. In comparison, 4 out of 39 patients (10.2%) had PNF in DDLT group while 20 patients (51.2%) had good early graft function; 8 patients (20.5%) died early within 2 months and 2 patients (5.1%) died late after transplantation. The LDLT group had a shorter cold ischemia time (CIT) of 4 hours in comparison to 9.2 hours in the DDLT group (p<0.0001).

CONCLUSIONS

LDLT is a lifesaving procedure for pediatric patients with ALF. Our experience showed that it may be performed with very good results, and with very low morbidity and no mortality among living donors when performed by experienced teams following strict procedures.

Ability of King's College Criteria and Model for End-Stage Liver Disease Scores to Predict Mortality of Patients With Acute Liver Failure: A Meta-analysis

BACKGROUND & AIMS

Several prognostic factors are used to identify patients with acute liver failure (ALF) who require emergency liver transplantation. We performed a meta-analysis to determine the accuracy of King's College criteria (KCC) versus the model for end-stage liver disease (MELD) scores in predicting hospital mortality among patients with ALF.

METHODS

We performed a systematic search of the literature for articles published from 2001 through 2015 that compared the accuracy of the KCC with MELD scores in predicting hospital mortality in patients with ALF. We identified 23 studies (comprising 2153 patients) and assessed the quality of data, and then performed a meta-analysis of pooled sensitivity and specificity values, diagnostic odds ratios (DORs), and summary receiver operating characteristic curves. Subgroups analyzed included study quality, era, location (Europe vs non-Europe), and size; ALF etiology (acetaminophen-associated ALF [AALF] vs nonassociated [NAALF]); and whether or not the study included patients who underwent liver transplantation and if the study center was also a transplant center.

RESULTS

The DOR for the KCC was 5.3 (95% confidence interval [CI], 3.7-7.6; 57% heterogeneity) and the DOR for MELD score was 7.0 (95% CI, 5.1-9.7; 48% heterogeneity), so the MELD score and KCC are comparable in overall accuracy. The summary area under the receiver operating characteristic curve values was 0.76 for the KCC and 0.78 for MELD scores. The KCC identified patients with AALF who died with 58% sensitivity (95% CI, 51%-65%) and 89% specificity (95% CI, 85%-93%), whereas MELD scores identified patients with AALF who died with 80% sensitivity (95% CI, 74%-86%) and 53% specificity (95% CI, 47%-59%). The KCC predicted hospital mortality in patients with NAALF with 58% sensitivity (95% CI, 54%-63%) and 74% specificity (95% CI, 69%-78%), whereas MELD scores predicted hospital mortality in patients with NAALF with 76% sensitivity (95% CI, 72%-80%) and 73% specificity (95% CI, 69%-78%). In patients with AALF, the KCC's DOR was 10.4 (95% CI, 4.9-22.1) and the MELD score's DOR was 6.6 (95% CI, 2.1-20.2). In patients with NAALF, the KCC's DOR was 4.16 (95% CI, 2.34-7.40) and the MELD score's DOR was 8.42 (95% CI, 5.98-11.88).

CONCLUSIONS

Based on a meta-analysis of studies, the KCC more accurately predicts hospital mortality among patients with AALF, whereas MELD scores more accurately predict mortality among patients with NAALF. However, there is significant heterogeneity among studies and neither system is optimal for all patients. Given the importance of specificity in decision making for listing for emergency liver transplantation, MELD scores should not replace the KCC in predicting hospital mortality of patients with AALF, but could have a role for NAALF.

Recellularization of rat liver scaffolds by human liver stem cells

In the present study, rat liver acellular scaffolds were used as biological support to guide the differentiation of human liver stem-like cells (HLSC) to hepatocytes. Once recellularized, the scaffolds were maintained for 21 days in different culture conditions to evaluate hepatocyte differentiation. HLSC lost the embryonic markers (alpha-fetoprotein, nestin, nanog, sox2, Musashi1, Oct 3/4, and pax2), increased the expression of albumin, and acquired the expression of lactate dehydrogenase and three subtypes of cytochrome P450. The presence of urea nitrogen in the culture medium confirmed their metabolic activity. In addition, cells attached to tubular remnant matrix structures expressed cytokeratin 19, CD31, and vimentin. The rat extracellular matrix (ECM) provides not only a favorable environment for differentiation of HLSC in functional hepatocytes (hepatocyte like) but also promoted the generation of some epithelial-like and endothelial-like cells. When fibroblast growth factor-epidermal growth factor or HLSC-derived conditioned medium was added to the perfusate, an improvement of survival rate was observed. The conditioned medium from HLSC potentiated also the metabolic activity of hepatocyte-like cells repopulating the acellular liver. In conclusion, HLSC have the potential, in association with the natural ECM, to generate in vitro a functional "humanized liver-like tissue."

In vitro study of N-acetylcysteine on coagulation factors in plasma samples from healthy subjects

INTRODUCTION

In the treatment of acetaminophen toxicity, clinicians believe that N-acetylcysteine (NAC) artificially elevates prothrombin time (PT). However, the effect of NAC on human blood coagulation remains unverified. In a previous study, we show that NAC had a dose-dependent effect on PT. To our knowledge, there are no studies that specifically examine the mechanism by which NAC affects PT. This study evaluates the effect from a therapeutic NAC dose on the activity of coagulation factors II, VII, IX, and X in human plasma.

METHOD

We obtained blood samples from ten volunteer subjects. After centrifugation of each volunteer's blood sample, the plasma was pipetted and divided into two 1-mL aliquots. We used the first-1 mL sample as a control. The second 1-mL plasma sample had 5 μL of 20 % NAC, added to make a final concentration of 1,000 mg of NAC per L of plasma. This concentration of NAC approximates the plasma levels achieved after a 150-mg/kg dose. We incubated the two samples for each subject (control and 1,000 mg/L) at 37°C for 1 h and measured the activity of coagulation factors II, VII, IX, and X. We compared factor activity using the paired student t test.

RESULTS

Participants included ten healthy subjects; six males, four females, median age 31 years. Mean values of the control samples for factors II, VII, IX, and X were 134 (CI 119-149), 126 (CI 90-163), 137 (CI 117-157), and 170 (CI 144-196) %, respectively. Mean values of the NAC-containing samples for factors II, VII, IX, and X were 90 (CI 79-100), 66 (CI 51-80), 74 (CI 63-85), and 81 (CI 71-90) %, respectively. All samples containing NAC had significantly lower coagulation factor activity level than their controls with a p < 0.001.

DISCUSSION

In a previous study, we were able to demonstrate that NAC had a dose-dependent effect on PT. In this study, we compared activity of factors II, VII, IX, and X at baseline and for samples that received NAC. All factor activity had a significant decrease with the addition of NAC. This fall in factor activity is not explained by the dilution of adding NAC to the test samples.

CONCLUSION

We are able to demonstrate a significant decrease in the activity of coagulation factors II, VII, IX, and X with the addition of NAC. This may be the mechanism by which PT increased in our previous study.

Understanding lactic acidosis in paracetamol (acetaminophen) poisoning

Paracetamol (acetaminophen) is one of the most commonly taken drugs in overdose in many areas of the world, and the most common cause of acute liver failure in both the UK and USA. Paracetamol poisoning can result in lactic acidosis in two different scenarios. First, early in the course of poisoning and before the onset of hepatotoxicity in patients with massive ingestion; a lactic acidosis is usually associated with coma. Experimental evidence from studies in whole animals, perfused liver slices and cell cultures has shown that the toxic metabolite of paracetamol, N-acetyl-p-benzo-quinone imine, inhibits electron transfer in the mitochondrial respiratory chain and thus inhibits aerobic respiration. This occurs only at very high concentrations of paracetamol, and precedes cellular injury by several hours. The second scenario in which lactic acidosis can occur is later in the course of paracetamol poisoning as a consequence of established liver failure. In these patients lactate is elevated primarily because of reduced hepatic clearance, but in shocked patients there may also be a contribution of peripheral anaerobic respiration because of tissue hypoperfusion. In patients admitted to a liver unit with paracetamol hepatotoxicity, the post-resuscitation arterial lactate concentration has been shown to be a strong predictor of mortality, and is included in the modified King's College criteria for consideration of liver transplantation. We would therefore recommend that post-resuscitation lactate is measured in all patients with a severe paracetamol overdose resulting in either reduced conscious level or hepatic failure.

Comparison of the applicability of two prognostic scoring systems in patients with fulminant hepatic failure

BACKGROUND

Distinguishing those patients with fulminant hepatic failure (FHF) and who require transplantation from those FHF patients who will survive with receiving only intensive medical care remains problematic, and this distinction is important because of the chronic shortage of donor livers.

METHODS

To assess the applicability of two prognostic scoring systems, referred to as the London and Clichy criteria, we compared using both systems, at the time of admission, for 43 FHF patients (15 M/28 F; age: 3716 yrs). Acetaminophen (ACM) was the etiology for 16 patients, while the remaining 27 had other etiologies. All the patients received intensive care, and 18 (8 ACM/10 non-ACM) had investigational BAL support.

RESULTS

For the ACM toxicity, neither the London nor the Clichy criteria exhibited acceptable sensitivity (71 vs 86%, respectively), specificity (78 vs 56%, respectively), a positive predictive value (71 vs 60%, respectively), a negative predictive value (78 vs 83%, respectively) or predictive accuracy (75 vs 69%, respectively) to predict patient survival without transplantation. In contrast, applying the London and Clichy criteria to the FHF patients with non-ACM etiologies showed a sensitivity of 96 vs 80%, respectively, a specificity of 100 vs 100%, respectively, a positive predictive value of 100 vs 100%, respectively a negative predictive value of 67 vs 29%, respectively and a predictive accuracy of 96% vs 82%, respectively.

CONCLUSIONS

Overall, the London criteria more accurately predicted the need for transplantation, and neither the London criteria nor the Clichy prognostic criteria accurately predicted the outcome of those patients who suffered with FHF due to ACM. BAL support may have contributed to the survival of the patients with ACM toxicity and who didn't undergo transplantation, and this survival exceeded the predictions of both prognostic systems. Additional multicenter studies should be conducted to refine these prognostic scoring systems, and this will help physicians rapidly identify those FHF patients who can survive without undergoing liver transplantation.

Acute Liver Failure

Acute liver failure (ALF) is an uncommon medical emergency whose rapid progression and high mortality demand early diagnosis and expert management, including immediate transfer of any potential case to facilities for intensive care and orthotopic liver transplantation (OLT). All patients with ALF must be screened aggressively for acetaminophen toxicity (history, serum levels, "hyperacute" presentation with renal failure), for other drugs, and viral hepatitis; rare causes of ALF should also be considered. After an acetaminophen overdose, N-acetylcysteine must be given as early as possible, preferably in the emergency room, but any patient with ALF should promptly receive N-acetylcysteine if there is suspicion of acetaminophen toxicity irrespective of the time of ingestion. Supportive care for all patients with ALF includes adequate enteral nutrition, aggressive screening and treatment of infection, prophylactic broad-spectrum antibiotics, and antifungal agents. Sedation with propofol is given for severe agitation or mechanical ventilation. With advanced coma grades, intensive care is needed with hemodynamic monitoring, ventilatory support, continuous renal replacement for renal failure, and intracranial pressure monitoring. Intracranial hypertension is treated with mannitol and/or acute short-term hyperventilation, but if the patient is refractory to treatment, mild-moderate hypothermia is achieved by a cooling blanket that is continued throughout OLT. Barbiturate coma is only used in refractory cases as the last treatment modality. Seizures are aggressively treated with phenytoin, with additional diazepam as needed. Candidacy and activation for OLT should be completed as early as possible in the course of ALF, especially in "hyperacute" cases such as acetaminophen toxicity. The final decision to proceed with OLT is made when a donor organ becomes available. King's College Hospital criteria for OLT are still the best prognostic assessment for fatal outcome in ALF, but the criteria fail to identify some patients who will die.

Recombinant activated factor VII (rFVIIa) as a hemostatic agent in liver disease: a break from convention in need of controlled trials

The management of coagulopathy in patients with acute and chronic liver disease has undergone little change in many years despite advances in our understanding of the pathogenesis of this problem. In general, deficiency of clotting factors as a result of poor hepatic synthetic function accounts for most of the coagulopathy. However, other processes such as disseminated intravascular coagulation (DIC), hyperfibrinolysis, dysfibrinogenemia, hemolysis, and a decrease in number or function of platelets may be present and thus add to the complexity of the problem. Coexisting portal hypertension and the associated risks of volume expansion, renal failure, and endothelial dysfunction add even more difficulty to the management of these patients. The clinician's despair is only exacerbated by uncertainty regarding the significance of laboratory indices of coagulation and the lack of agreement between health care providers regarding how to use these indices. Simple, conventional interventions such as vitamin K or plasma administration often produce only limited amelioration, and the latter carries the potential disadvantage of volume overexpansion as well as the risk of infection and transfusion reactions. Into this complex and uncertain clinical situation has arrived the antihemophilic agent recombinant activated factor VII (rFVIIa). Its development has led to a fundamental re-evaluation of the classic understanding of the normal clotting cascade. Moreover, use of this product in liver disease patients is increasing despite the lack of definitive studies or literature to guide therapy. Herein we review the mechanism of action of this agent, report the clinical applications in patients with liver disease, address the limitations and risks associated with the drug, and discuss the issue of its cost-effectiveness.

Recombinant activated factor VII for coagulopathy in fulminant hepatic failure compared with conventional therapy

Severe coagulopathy in fulminant hepatic failure (FHF) is difficult to correct by conventional means. Recombinant activated factor VII (rFVIIa) is an antihemophilic factor that has shown promise in treating coagulopathy in liver disease. Our aim is to review our experience with rFVIIa in treating the coagulopathy of FHF and compare these results with those of conventional therapy. Fifteen patients with FHF who met King's College criteria for orthotopic liver transplantation were studied. All were ascertained from our liver disease registry. Eight consecutive patients were administered fresh frozen plasma (FFP) alone, whereas seven consecutive patients were administered FFP and rFVIIa (40 microg/kg intravenous bolus). The two groups, with similar demographic characteristics, were compared in terms of measured parameters of coagulopathy (prothrombin time and international normalized ratio), amount of plasma infused, development of anasarca, ability to undergo intracranial pressure (ICP) transducer placement, bleeding complications, ability to undergo transplantation, and survival. All patients administered rFVIIa (after a single dose) versus none administered FFP alone had temporary (2- to 6-hour) correction of coagulopathy (P <.0002). All patients administered rFVIIa versus 38% administered FFP alone were able to have an ICP transducer placed (P =.03). The rFVIIa group had less anasarca (P =.04). An equal number of patients underwent transplantation from each group, but overall survival was slightly better in the rFVIIa group (P =.04). Five of seven patients in the rFVIIa group were administered one or more subsequent doses of rFVIIa after placement of the ICP monitor (two patients, for additional procedures; three patients, prophylactically in the first 24 hours after ICP transducer placement) at the discretion of the attending physicians. We conclude that rFVIIa is effective in transiently correcting laboratory parameters of coagulopathy in patients with FHF. It facilitates the performance of invasive procedures and is associated with less frequent anasarca compared with conventional therapy. Our preliminary experience supports the need for further studies to define the optimal dosing, safety, and efficacy of rFVIIa in patients with FHF.

Liver transplantation for fulminant hepatitis at Stanford University

BACKGROUND

To review the clinical characteristics and outcomes of 26 patients evaluated for liver transplantation for fulminant hepatic failure at Stanford University and Lucile Packard Children's Hospital in an attempt to identify risk factors and prognostic predictors of survival.

METHODS

A retrospective review of the records of 26 consecutive patients who were evaluated for possible liver transplantation for acute liver failure from May 1, 1995, to January 1, 2000. Pretransplant patient demographics and clinical characteristics were collected, and the data were analyzed by univariate and multivariate analysis.

RESULTS

Clinical assessment of encephalopathy did not predict outcome. Patients with abnormal computed tomography (CT) of the brain had a twofold increase in mortality compared with those patients with normal studies (p = 0.03). Patients requiring mechanical ventilation and continuous venovenous hemofiltration (CVVH) also had a poor prognosis.

CONCLUSION

Predictors of poor outcome after fulminant hepatic failure include abnormal CT scan, mechanical ventilation, and requirement for hemofiltration.

Blood lactate as an early predictor of outcome in paracetamol-induced acute liver failure: a cohort study

BACKGROUND

Although the King's College Hospital (KCH) selection criteria for emergency liver transplantation in paracetamol-induced acute liver failure are widely used, strategies to improve sensitivity and facilitate earlier transplantation are required. We investigated the use of arterial blood lactate measurement for the identification of transplantation candidates.

METHODS

In a single-centre study, we measured arterial blood lactate early (median 4 h) and after fluid resuscitation (median 12 h) in patients admitted to a tertiary-referral intensive-care unit. Threshold values that best identified individuals likely to die without transplantation were derived in a retrospective initial sample of 103 patients with paracetamol-induced acute liver failure and applied to a prospective validation sample of 107 patients. Predictive value and speed of identification were compared with those of KCH criteria.

FINDINGS

In the initial sample, median lactate was significantly higher in non-surviving patients than in survivors both in the early samples (8.5 [range 1.7--21.0] vs 1.4 [0.53--7.9] mmol/L, p<0.0001) and after fluid resuscitation (5.5 [1.3--18.6] vs 1.3 [0.26--3.2], p<0.0001). Applied to the validation sample, a threshold value of 3.5 mmol/L early after admission had sensitivity 67%, specificity 95%, positive likelihood ratio 13, and negative likelihood ratio 0.35; the corresponding values for a threshold of 3.0 mmol/L after fluid resuscitation were 76%, 97%, 30, and 0.24. Combined early and postresuscitation lactate concentrations had similar predictive ability to KCH criteria but identified non-surviving patients earlier (4 [3--13] vs 10 [3.5--19.5] h, p=0.01). Addition of postresuscitation lactate concentration to KCH criteria increased sensitivity from 76% to 91% and lowered negative likelihood ratio from 0.25 to 0.10.

INTERPRETATION

Arterial blood lactate measurement rapidly and accurately identifies patients who will die from paracetamol-induced acute liver failure. Its use could improve the speed and accuracy of selection of appropriate candidates for transplantation.