Acute liver failure









  • Pediatric acute liver failure represents a large number of heterogenous etiologies.



  • Effective diagnosis requires a systemic approach; however, despite thorough workup, in a large proportion of cases, cause cannot be determined at present.



  • Prognostication is remarkably difficult in that spontaneous recovery has occurred even in patients with advanced hepatic necrosis, deep coma, and severe coagulopathy. Prognostic tools have been designed, but all have been found to be fallible and clinical experience is invaluable.



  • Orthotopic liver transplantation is lifesaving, and early transfer to an experienced liver transplant center is advisable for all children with coagulopathy secondary to acute liver disease.



  • Oversedation is to be avoided because it increases the risk of complications and prolongs stay in the intensive care unit and total length of hospital stay after liver transplantation.



Pediatric acute liver failure (PALF) is a life-threatening condition in which previously healthy children lose hepatic function rapidly, requiring immediate medical attention. It is a rare entity in pediatric intensive care unit (PICU) settings, but expertise is crucial to achieving optimal outcomes. Management consists of supportive measures, with a focus on anticipation, prevention, and treatment of complications along with early consideration for liver transplantation. Timely intervention to treat the metabolic derangements associated with acute liver failure (ALF) is pivotal and can help mitigate the morbidity associated with this condition.


This chapter focuses on acute liver injury; it does not detail the management of end-stage and life-threatening complications of chronic liver disease


Acute liver failure


Background, definitions, etiology, outcomes


Liver failure is defined as the loss of normal liver function that includes synthesis of serum proteins, including clotting factors and albumin; metabolism and storage of glucose and fatty acids; and detoxification and excretion of exogenous and endogenous molecules, such as drugs and products of protein metabolism, most notably ammonia. Evidence of liver failure is reflected in elevations of prothrombin time, bilirubin, and ammonia. In the United States, the incidence of PALF has been estimated at 17 cases per 100,000 per year.


Diagnosis of hepatic encephalopathy (HE) in children is challenging, as it might be present only in very late stages of the disease. This makes the definition of adult acute or fulminant liver failure, which includes the onset of HE within 8 weeks of the first signs of liver disease, to be difficult to apply to infants and children. Subacute liver failure has been defined as the development of HE after 8 weeks and before 24 weeks from the onset of liver disease in the absence of preexisting chronic liver disorders.


Etiologies


PALF is a heterogeneous condition, with a broad range of etiologies. It is age dependent, including infections, toxin- and drug-related injuries; metabolic disorders; and immunologic, ischemic, and irradiation damage. Despite the many known causes of PALF, a specific etiology is not determined in up to 50% of cases, , accounting for 40% of PALF among patients younger than age 3 years and 60% in those age 3 years and older. The large number of indeterminate causes is due to several factors, including hepatic improvement prior to finishing clinical workup, lack of current available testing for all etiologies, or lack of a thorough workup. The term indeterminate etiology should prompt further investigation. Liver biopsy is indicated, as it can further help with diagnosis and treatment. Liver biopsy can be performed safely via transjugular or percutaneous approach, but the risk of bleeding should be evaluated case by case.


Of the known etiologies, severe viral hepatitis—especially due to enteroviruses, adenovirus, and herpesvirus—may occur in the neonatal population. Infantile causes of ALF also include gestational autoimmune liver disease (GALD), inborn errors of metabolism, and hemophagocytic lymphohistiocytosis (HLH). HLH is a challenging diagnosis, as it can present at any age with PALF, and correct diagnosis is very important due to specific treatment (see also Chapter 106 ). Acute hepatitis A and B infections are rare causes of PALF in North America but are a common cause of PALF in school-aged children in developing countries. Drug-induced liver disease is more common in older children, especially secondary to intentional acetaminophen overdose ( Box 96.1 ).



• BOX 96.1

BP, Blood pressure; CVP, central venous pressure; FFP, fresh frozen plasma; PN, parenteral nutrition; PT, prothrombin time; PTT, partial thromboplastin time.

Intensive Care Unit Management


No sedation except for procedures


Lines and tubes





  • Multilumen central venous catheter



  • Arterial tube



  • Nasogastric tube



  • Urinary Foley catheter



  • Bed scale



Monitor





  • Heart and respiratory rate



  • Arterial BP, CVP



  • Core/toe temperature



  • Neurologic function



  • Gastric pH (>5)



  • Blood glucose (>4 mmol/L)



  • Acid-base



  • Electrolytes



  • PT, PTT



Fluid balance





  • 75%–95% maintenance



  • Dextrose 10%–25%



  • Sodium (2–3 mEq/kg/day)



Maintain circulating volume with colloid/FFP


Coagulation support only if required


Drugs





  • Vitamin K



  • H 2 antagonist



  • Antacids



  • Lactulose



  • N -acetylcysteine for acetaminophen toxicity



  • Broad-spectrum antibiotics



  • Antifungals



Nutrition





  • Enteral feeding (1–2 g protein/kg/day)



  • PN if ventilated




To determine outcomes, investigate prognostic factors, and further decipher etiologies, the Pediatric Acute Liver Failure Study Group (PALF-SG)—involving 24 pediatric liver centers in the United States, Canada, and the United Kingdom—formed in 1999. The study’s entry criteria include evidence of hepatic injury without known chronic liver disease manifesting as an international normalized ratio (INR) of 1.5 and encephalopathy or INR of 2.0 with or without encephalopathy. The group has reported data on 348 subjects over a 6-year period and concluded that survival and the need for liver transplantation depend on age and diagnosis. For established PALF etiologies, liver transplantation is necessary in 20% to 33% of cases versus 46% in indeterminate cases, whereas spontaneous recovery ranged from 46% to 60% depending on diagnosis and age categories.


Prognostic assessment


Several attempts to produce prognostic tools based on a snapshot of clinically available data either at presentation or at peak values have been attempted, but all have been found wanting. Three of the more often quoted include the King’s College Hospital Criteria (KCHC), the liver injury unit (LIU) score, and the Clichy criteria. The Clichy criteria are primarily derived from adult patients with acute hepatitis B infection; thus, its utility in the pediatric population has always been in doubt. The KCHC applied to the PALF-SG cohort fails to reliably identify those patients at risk of death. The LIU score predicted those who eventually underwent transplantation but was not a reliable predictor of death. This is not particularly surprising, as the LIU calculation is based on levels of bilirubin, ammonia, and prothrombin time (PT), all of which are used clinically to determine who might benefit from transplantation and, as such, were self-fulfilling predictors. All of these tools suffer from the fact that no account is taken for the dynamic nature of PALF. Further work would benefit from examining the trends over time rather than data at a single time point. ,


Diagnosis and workup


The care team should obtain a full history, including information about infectious illnesses, behavior changes, the time course of the development of jaundice, and foreign travel. It is important to establish what medications the child has taken, including over-the-counter preparations, acne medications, folk remedies, and herbal supplements, as well as determining what other medications might be in the household. In adolescents, inquiries should be made about the use of illicit drugs, potential for self-harm, and sexual contact.


Acute hepatic dysfunction often first manifests as jaundice and general malaise. Hepatomegaly may be present, but the liver edge is frequently soft and difficult to palpate. Splenomegaly is unusual, and its presence may point to a metabolic or hematologic diagnosis. Petechiae or ecchymoses can be associated with coagulopathy. The patient’s level of consciousness and degree of HE ( Box 96.2 ) should be established using a reliable scale, , , and a complete central nervous system examination should be performed, including examination of reflexes and mental status. Parental help in the assessment of mental status is perhaps one of the best indicators of deviation from baseline neurologic status. Serial neurologic examinations should be conducted once the baseline is established to identify any progression of encephalopathy as there is significant risk for increased intracranial pressure (ICP) and herniation due to cerebral edema or intracranial bleeding. The presence of moderate to severe impaired central nervous system function or rapid neurologic deterioration in the setting of acute liver disease should be an indication for admission to the PICU. Work of breathing should be assessed and assisted with positive pressure or mechanical ventilation if needed to ensure adequate ventilation and oxygenation. Monitoring of and, if necessary, intervention for glycemic control, acid–base balance, and adequate tissue perfusion should be included in the care plan. Antibiotics and antiviral medications should be started if an infectious cause is suspected.



• BOX 96.2

Causes of Pediatric Acute Liver Failure


Viral





  • Hepatitis A cytomegalovirus



  • Hepatitis B paramyxovirus



  • Hepatitis D adenovirus



  • Hepatitis E enterovirus



  • Herpes simplex virus



  • Parvovirus B19



  • Varicella zoster virus



  • Severe acute respiratory syndrome



  • Epstein-Barr virus



  • Hemorrhagic fever virus



Bacterial





  • Septicemia



  • Bartonella



  • Leptospirosis



  • Rocky Mountain spotted fever



  • Salmonella typhi/paratyphi



Metabolic





  • Hereditary fructose intolerance



  • Carnitine defects



  • Urea cycle disorders



  • Wilson disease



  • Organic acidemias



  • Tyrosinemia type 1



  • Fatty acid oxidation defects



  • Niemann-Pick type C



  • Mitochondrial disorders



  • Acute fatty liver of pregnancy



Immune





  • Autoimmune hepatitis



  • Hemophagocytic lymphohistiocytosis



  • Neonatal hemochromatosis



  • Autoimmune hemolytic anemia with giant cell hepatitis



Toxic





  • Drugs/toxins/herbal



  • Amanita phalloides



Vascular





  • Budd-Chiari postcardiac surgery



  • Venoocclusive disease



  • Liver trauma



  • Ischemic hepatitis/shock liver



Neoplastic





  • Leukemia



  • Lymphoma



  • Hepatocellular carcinoma



Other





  • Reye syndrome



  • Massive liver resection



  • Hypothermia



  • Sickle cell anemia



  • Heat stroke




Once in the PICU, a central venous catheter should be placed for administration of medication and intravenous fluids, including parenteral nutrition and high glucose infusion rate, as well as for hemodynamic monitoring and frequent blood draws. An arterial line should be considered for patients with clinical deterioration or with HE. Urinary catheter placement can also be considered to ensure accurate fluid balance estimation and assessment of kidney function ( Table 96.1 ).



TABLE 96.1

Clinical Stages of Hepatic Encephalopathy


































Stage Asterixis EEG Changes Clinical Manifestations
0 None None Normal
I (prodrome) Slight


  • Infant/child: Difficult or impossible to test adequately



  • Adult: Normal or diffuse slowing to theta rhythm, triphasic waves




  • Infant/child: Inconsolable crying, child not acting like self to parents



  • Adult: Mild intellectual impairment, disturbed sleep-wake cycle

II (impending) Easily elicited


  • Infant/child: Difficult or impossible to test adequately



  • Adult: Generalized slowing, triphasic waves




  • Infant/child: Inconsolable crying, child



  • Adult: Drowsiness, confusion, coma/inappropriate behavior, disorientation, mood swings

III (stupor) Present if patient cooperative


  • Infant/child: Difficult or impossible to test adequately



  • Adult: Grossly abnormal slowing of rhythm, triphasic waves




  • Infant/child/adult: Drowsy, unresponsive to verbal commands, markedly confused, stupor, combative, hyperreflexia, positive Babinski sign

IV (coma) Usually absent


  • Infant/child/adult: Appearance of delta waves, decreased amplitudes




  • Infant/child/adult: Unconscious, decerebrate, or decorticate response to pain present (stage IVA) or absent (stage IVB)


EEG, Electroencephalography.


A basic workup for PALF with investigations reflecting age-dependent etiologies is suggested in Box 96.3 . Initial monitoring of blood work should include complete blood count, blood gases, lactate levels, glucose, electrolytes, aminotransferases, PT/INR, creatinine, bilirubin, and ammonia. Monitoring blood work should be repeated every 6 to 12 hours until the clinical course is determined. If the patient may require liver transplantation, a referral to a pediatric liver transplant center should be initiated in a timely manner, prior to clinical decompensation.



• BOX 96.3

ALT, alanine aminotransferase; AST, aspartate aminotransferase; BUN, blood urea nitrogen; CBC, complete blood count; CMV, cytomegalovirus; DNA, deoxyribonucleic acid; EBV, Epstein-Barr virus; GGT, γ-glutamyltransferase; hCG, human chorionic gonadotropin; HSV, herpes simplex virus; IgG, immunoglobulin G; IgM, immunoglobulin M; IL, interleukin; INR, international normalized ratio; PT, prothrombin time.

Diagnostic Workup


Hematology





  • CBC with differential



  • PT/INR



  • Factor V level



  • Factor VII level



  • Fibrinogen level



  • ABO/Rh typing



Chemistry





  • Electrolytes



  • Calcium, magnesium, phosphorus



  • BUN, creatinine



  • Glucose



  • Lactate, pyruvate



  • Bilirubin conjugated and unconjugated



  • AST, ALT



  • GGT



  • Alkaline phosphatase



  • Cholesterol, triglycerides



  • Ferritin



  • Blood gases



  • α-fetoprotein



  • Acylcarnitine profile (children ≤3 mo)



  • Amino acid quantitative



  • Ceruloplasmin (children ≥3 y)



  • Copper (children ≥3 y)



  • β-hCG (females ≥12 y)



Immunology





  • IgG level



  • Antinuclear antibody (children ≥3 y)



  • Antismooth muscle antibody (children ≥3 y)



  • Antiliver kidney microsomal antibody (children ≥3 y)



  • Antineutrophil cytoplasmic antibody (children ≥3 y)



  • Antisoluble liver antigen



  • Soluble IL-2 receptor



Microbiology





  • HSV DNA



  • Enterovirus DNA (children ≤3 mo)



  • CMV DNA



  • EBV DNA



  • Varicella DNA



  • Adenovirus DNA



  • Parvovirus B19 DNA



  • Toxoplasma IgG and IgM (children ≤3 mo)



  • Hepatitis A IgM


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Jun 26, 2021 | Posted by in CRITICAL CARE | Comments Off on Acute liver failure
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