What a Nephrologist Needs to Know About Acute Liver Failure

The Kidney and Extracorporeal Therapies in Acute-on-Chronic Liver Failure: What the Nephrologist Needs to Know

In this review, we discuss the pathophysiology and management of acute kidney injury (AKI) in the setting of acute-on-chronic liver failure (ACLF). ACLF is characterised by the occurrence of acute hepatic and/or extrahepatic organ failure, induced by immune dysregulation and systemic inflammation in patients with chronic liver disease. Kidney involvement is common, with AKI occurring in 30% to > 95% of ACLF patients, depending on the definition used. Since there is a lack of kidney biopsy data in these patients, the underlying pathophysiological basis of AKI remains incompletely understood, and systemic inflammation is believed to be the primary driver of organ injury. The management of AKI has been largely extrapolated from studies in decompensated cirrhosis, and there is little data specifically in the ACLF setting. However, available evidence suggests that structural kidney injury is more common in ACLF than in decompensated CLD, and therefore, AKI in ACLF is less likely to respond to volume repletion and vasopressors. Treatment options remain limited for those who are non-responsive to intravenous fluids and vasopressors. Liver transplantation (LT), with or without kidney transplantation, is the definitive treatment for these patients. At present, extracorporeal therapies such as therapeutic plasma exchange and kidney replacement therapies play a supportive role in ACLF as a bridge to LT; however, the optimal timing and dosing remain unclear. While theoretically, extracorporeal therapies have the potential to reverse or halt progression of organ damage in ACLF, there is limited evidence currently.

Intraoperative kidney replacement therapy in acute liver failure

Paediatric acute liver failure (PALF) is often characterised by its rapidity of onset and potential for significant morbidity and even mortality. Patients often develop multiorgan dysfunction/failure, including severe acute kidney injury (AKI). Whilst the management of PALF focuses on complications of hepatic dysfunction, the associated kidney impairment can significantly affect patient outcomes. Severe AKI requiring continuous kidney replacement therapy (CKRT) is a common complication of both PALF and liver transplantation. In both scenarios, the need for CKRT is a poor prognostic indicator. In adults, AKI has been shown to complicate ALF in 25-50% of cases. In PALF, the incidence of AKI is often higher compared to other critically ill paediatric ICU populations, with reports of up to 40% in some observational studies. Furthermore, those presenting with AKI regularly have a more severe grade of PALF at presentation. Observational studies in the paediatric population corroborate this, though data are not as robust-mainly reflecting single-centre cohorts. Perioperative benefits of CKRT include helping to clear water-soluble toxins such as ammonia, balancing electrolytes, preventing fluid overload, and managing raised intracranial pressure. As liver transplantation often takes 6-10 h, it is proposed that these benefits could be extended to the intraoperative period, avoiding any hiatus. Intraoperative CKRT (IoCKRT) has been shown to be practicable, safe and may help sicker recipients tolerate the operation with outcomes analogous with less ill patients not requiring IoCKRT. Here, we provide a comprehensive guide describing the rationale, practicalities, and current evidence base surrounding IoCKRT during transplantation in the paediatric population.

Acute kidney injury in acute liver failure: A narrative review

Acute kidney injury (AKI) is a frequent complication of acute liver failure (ALF) and it worsens the already worse prognoses of ALF. ALF is an uncommon disease, with varying etiologies and varying definitions in different parts of the world. There is limited literature on the impact of AKI on the outcome of ALF with or without transplantation. The multifaceted etiology of AKI in ALF encompasses factors such as hemodynamic instability, systemic inflammation, sepsis and direct nephrotoxicity. Indications of renal replacement therapy (RRT) for AKI in ALF patients extend beyond the conventional criteria for dialysis and continuous renal replacement therapy (CRRT) may have a role in transplant-free survival or bridge to liver transplantation (LT). LT is a life-saving option for ALF, so despite somewhat lower survival rates of LT in ALF patients with AKI, LT is not usually deferred. In this review, we will discuss the guidelines' recommended definition and classification of AKI in ALF, the impact of AKI in ALF, the pathophysiology of AKI and the role of CRRT and LT in ALF patients with AKI.

Kidney Outcomes Following Utilization of Molecular Adsorbent Recirculating System

Introduction

Molecular adsorbent recirculating system (MARS) is an extracorporeal system combining conventional veno-venous hemodiafiltration and adsorption to provide rescue support in fulminant hepatic failure. Acute kidney injury (AKI) is common in patients with hepatic failure warranting continuous kidney replacement therapy (CKRT). Our primary aim was to characterize a cohort of patients who received MARS therapy and examine kidney events given the current paucity of available data.

Methods

Patients initiating MARS in a tertiary care setting from January 2014 through December 2020 were assessed for treatment indications, transplantation, CKRT, kidney recovery, and death. Data was collected using the REDCAP software.

Results

A total of 49 patients (67% female; 75% White) received MARS therapy with 29 patients (59%) requiring concomitant CKRT. Hepatic encephalopathy (HE) was the most common indication for MARS initiation (55%). In-hospital mortality was 41% (12/29) among patients who received CKRT versus 10% (2/20) among those not requiring CKRT (relative risk [RR] 4.15, 95% confidence interval [CI] 1.04 to 16.52, P = 0.044); this persisted following adjustment for prespecified patient characteristics (all RR ≥ 3.76, all P ≤ 0.060). One-year mortality post-MARS initiation was high overall but highest among the CKRT group (59% [17/29] vs. 25% [5/20] unadjusted RR 2.92, 95% CI 1.08 to 7.94, P = 0.035). Liver transplant after MARS occurred in 41% of patients (20/49). After CKRT, 39% of patients (9/29) recovered kidney function prior to hospital discharge.

Conclusions

Patients requiring MARS frequently have AKI warranting the use of concomitant CKRT, which is associated with a high rate of in-hospital and 1-year mortality.

Acute kidney injury in the critical care setting

Acute kidney injury is a sudden reduction in renal function which impairs the kidneys' ability to maintain fluid, electrolyte and acid-base balance. The syndrome often develops secondary to severe illness and is associated with a significant increase in morbidity and mortality rate in critically ill patients. This article gives an overview of the pathophysiology and aetiology of acute kidney injury, as well as the associated complications and clinical diagnostic signs. The authors also describe some common causes of the syndrome in critically ill patients, specifically sepsis, liver failure and cardiac failure, and discuss patient management in the critical care setting, with a focus on haemodynamic support and continuous renal replacement therapy.

Multiple organ involvement and ICU considerations for the care of acute liver failure (ALF) and acute on chronic liver failure (ACLF) in children

Liver disease results in approximately 15,000 pediatric hospitalizations per year in the United States and is a significant burden to child health. Major etiologies of liver failure and indications for transplantation in children include: biliary atresia, metabolic/genetic conditions, toxins, infections, tumors, and immune-mediated liver/biliary injury. Children requiring transplantation are placed on the United Network of Organ Sharing waitlist including those with acute liver failure (ALF) and acute on chronic liver failure (ACLF). ALF is a clinical syndrome in which a previously healthy child develops rapid-onset hepatic dysfunction, and becomes critically ill with multiple organ dysfunction within days. ACLF, by contrast, is generally described as an acute decompensation of pre-existing chronic liver disease (CLD) brought on by a precipitating event, with higher risk of mortality. Children with ALF and ACLF receive multidisciplinary care in pediatric intensive care units (ICUs) due to multiple organ system involvement and high risk of decompensation in these patients. The care of these patients requires a holistic approach that addresses the complex interplay between hepatic and extra-hepatic organ systems. This review will define and describe ALF and ACLF in the pediatric population, and outline the effects of ALF and ACLF on individual organ systems with diagnostic and management considerations in the ICU while awaiting liver transplantation.

4-methylpyrazole protects against acetaminophen-induced acute kidney injury

Acetaminophen (APAP) hepatotoxicity is the most common cause of acute liver failure in the United States, and while a significant percentage of APAP overdose patients develop kidney injury, molecular mechanisms involved in APAP-induced nephrotoxicity are relatively unknown. We have shown that 4-methylpyrazole (4MP, Fomepizole) protects against APAP-induced liver injury by inhibiting reactive metabolite formation through Cyp2E1, and analysis of data from APAP overdose patients indicated that kidney dysfunction strongly correlated with severe liver injury. Since Cyp2E1 is also expressed in the kidney, this study explored protection by 4MP against APAP-induced nephrotoxicity. Male C57BL/6 J mice were treated with either 300 or 600 mg/kg APAP with or without 4MP for 2, 6 or 24 h, followed by measurement of APAP metabolism and tissue injury. Interestingly, levels of APAP and its non-oxidative metabolites were significantly higher in kidneys when compared to the liver. APAP-protein adducts were present in both tissues within 2 h, but were absent in kidney mitochondria, unlike in the liver. While GSH depletion was seen in both tissues, activation of c-jun N-terminal kinase and its translocation to the mitochondria, which is a critical feature of APAP-induced liver injury, was not detected in the kidney. Treatment with 4MP attenuated APAP oxidative metabolite generation, GSH depletion as well as kidney injury indicating its potential use in protection against APAP-induced nephrotoxicity. In conclusion, since reactive metabolite formation seems to be common in both liver and kidney, 4MP mediated inhibition of Cyp2E1 protects against APAP-induced nephrotoxicity. However, downstream mechanisms of APAP-induced nephrotoxicity seem distinct from the liver.

Acute Kidney Damage: Definition, Classification and Optimal Time of Hemodialysis

Acute damage to the kidney is a serious complication in patients in intensive care units. The causes of acute kidney damage in these patients may be prerenal, renal and postrenal. Sepsis is the most common cause of the development of acute kidney damage in intensive care units. For the definition and classification of acute kidney damage in clinical practice, the RIFLE, AKIN and KDIGO classifications are used. There is a complex link between acute kidney damage and other organs. Acute kidney damage is induced by complex pathophysiological mechanisms that cause acute damage and functional disorders of the heart (acute heart failure, acute coronary syndrome and cardiac arrhythmias), brain (whole body cramps, ischaemic stroke and coma), lung (acute damage to the lung and acute respiratory distress syndrome) and liver (hypoxic hepatitis and acute hepatic insufficiency). New biomarkers, colour Doppler ultrasound diagnosis and kidney biopsy have significant roles in the diagnosis of acute kidney damage. Prevention of the development of acute kidney damage in intensive care units includes maintaining an adequate haemodynamic status in patients and avoiding nephrotoxic drugs and agents (radiocontrast agents). The complications of acute kidney damage (hyperkalaemia, metabolic acidosis, hypervolaemia and azotaemia) are treated with medications, intravenous solutions, and therapies for renal function replacement. Absolute indications for acute haemodialysis include resistant hyperkalaemia, severe metabolic acidosis, resistant hypervolaemia and complications of high azotaemia. In the absence of an absolute indication, dialysis is indicated for patients in intensive care units at stage 3 of the AKIN/KDIGO classification and in some patients with stage 2. Intermittent haemodialysis is applied for haemodynamically stable patients with severe hyperkalaemia and hypervolaemia. In patients who are haemodynamically unstable and have liver insufficiency or brain damage, continuous modalities of treatment for renal replacement are indicated.

Human hepatocellular adenoma as a promising cell source for bioartificial liver systems

The present study assessed human hepatocellular adenoma (HCA) as a potential source of biological material for bioartificial liver (BAL) systems. The histological characteristics of HCA tissues from 8 patients were examined using hematoxylin and eosin staining. The glycogen synthesis capacity of HCA cells was assessed using Periodic Acid-Schiff (PAS) staining and the expression of genes involved in liver function were examined using immunohistochemical staining (IHC) and reverse transcription-quantitative PCR analysis. Primary cells from HCA tissues were subsequently isolated and cultured in vitro. Cells within HCA tissues from 8 patients exhibited a polygonal shape, similar to that of cells in adjacent normal liver tissues. PAS staining of HCA tissues indicated the capacity of these cells to synthesize and store glycogen. Furthermore, IHC and PCR analyses revealed that the expression of liver function genes in HCA tissues were similar to those observed within normal adjacent liver tissues. Primary cells isolated from HCA tissues exhibited an irregular polygonal shape and positive in vitro growth. The current study demonstrated that HCA tissues exhibit histological and functional characteristics matching those of normal human liver tissue and may therefore be a promising alternative to hepatocytes as a source of biological material for BAL systems.

Acute Liver Failure: An Update

Pediatric acute liver failure (PALF) is a dynamic, life-threatening condition of disparate etiology. Management of PALF is dependent on intensive collaborative clinical care and support. Proper recognition and treatment of common complications of liver failure are critical to optimizing outcomes. In parallel, investigations to identify underlying cause and the implementation of timely, appropriate treatment can be life-saving. Predicting patient outcome in the era of liver transplantation has been unfulfilling and better predictive models must be developed for proper stewardship of the limited resource of organ availability.

Medical Management of Acute Liver Failure

Pediatric acute liver failure is a rapidly progressive, life-threatening, and devastating illness in children without preexisting liver disease. Due to the rarity and heterogeneity of this syndrome, there is a significant lack of data to guide evaluation and management of this disease. Most of our practice is extrapolated from adult literature and guidelines. This leads to significant controversies in medical management of acute liver failure in children. With advances in critical care, there has been a tremendous improvement in outcomes with decreased morbidity and mortality; however, there is a dire need for more research in this field. This chapter discusses challenges as well as controversies in diagnostic evaluation and management of this rare but potentially fatal disease. Latest developments in supportive care of liver failure, including advances in the area of liver support systems, are also discussed.

Management of Acute Liver Failure: A Pediatric Perspective

Purpose of Review

Pediatric acute liver failure is a rare, complex, rapidly progressing, and life-threatening illness. Majority of pediatric acute liver failures have unknown etiology. This review intends to discuss the current literature on the challenging aspects of management of acute liver failure.

Recent Findings

Collaborative multidisciplinary approach for management of patients with pediatric acute liver failure with upfront involvement of transplant hepatologist and critical care specialists can improve outcomes of this fatal disease. Extensive but systematic diagnostic evaluation can help to identify etiology and guide management. Early referral to a transplant center with prompt liver transplant, if indicated, can lead to improved survival in these patients.

Summary

Prompt identification and aggressive management of pediatric acute liver failure and related comorbidities can lead to increased transplant-free survival and improved post-transplant outcomes, thus decreasing mortality and morbidity associated with this potential fatal condition.

Acute Liver Failure: Mechanisms of Disease and Multisystemic Involvement

Acute liver failure is accompanied by a pathologic syndrome common to numerous different etiologies of liver injury. This acute liver failure syndrome leads to potentially widespread devastating end-organ consequences. Systemic dysregulation and dysfunction is likely propagated via inflammation as well as underlying hepatic failure itself. Decoding the mechanisms of the disease process and multisystemic involvement of acute liver failure offers potential for targeted treatment opportunities and improved clinical outcomes in this sick population.

Intensive Care Management of Pediatric Acute Liver Failure

Pediatric acute liver failure is rare but life-threatening illness that occurs in children without preexisting liver disease. The rarity of the disease, along with its severity and heterogeneity, presents unique clinical challenges to the physicians providing care for pediatric patients with acute liver failure. In this review, practical clinical approaches to the care of critically ill children with acute liver failure are discussed with an organ system-specific approach. The underlying pathophysiological processes, major areas of uncertainty, and approaches to the critical care management of pediatric acute liver failure are also reviewed.