acute liver diseases
Definition
() It is an uncommon but serious syndrome, define as a disease occurring within 8 weeks of onset of the precipitating illness, in the absence of evidence of pre-existing liver disease.
() The presentation is with mental changes progressing from confusion to stupor and coma, and a progressive deterioration in liver function.
() This distinguishes it from instances in which hepatic encephalopathy represents adeterioration in chronic liver disease
() Acute viral hepatitis is the most common cause world-wide, In 10% of cases the cause of acute liver failure remains unknown and these patients are often labelled as having non-A-E viral hepatitis or cryptogenic acute liver failure.
Clinical assessment
() cerebral disturbance (hepatic encephalopathy) is the cardinal feature of acute liver failure:
Grade 1: Poor concentration, slurred speech, slow mentation, disordered sleep rhythm
Grade 2: Drowsy but easily rousable, occasional aggressive behaviour, lethargic
Grade 3: Marked confusion, drowsy, sleepy but responds to pain and voice, gross disorientation
Grade 4: Unresponsive to voice, may or may not respond to painful stimuli, unconscious
(*)Cerebral oedema may occur due to increased intracranial pressure causing unequal or abnormally reacting pupils, fixed pupils, hypertensive episodes, bradycardia, hyperventilation, profuse sweating, local or general myoclonus, focal fits or decerebrate posturing.
(*)Papilloedema occurs rarely and is a late sign.
(*)More general symptoms include weakness, nausea and vomiting.
(*)Right hypochondrial discomfort is an occasional feature.
(*)The patient is usually jaundiced, except in Reye s syndrome when jaundice is rare.
(*)Occasionally, death may occur in fulminant cases of acute liver failure before jaundice develops.
(*)Fetor hepaticus can be present.
(*) The liver is usually of normal size but later becomes smaller. Hepatomegaly is unusual and, in the presence of a sudden onset of ascites, suggests venous outflow obstruction as the cause (Budd-Chiari syndrome).
(*) Splenomegaly is uncommon and never prominent.
(*)Ascites and oedema are late developments and may be a consequence of fluid therapy.
Investigations
Toxicology screen of blood and urine
HBsAg, IgM anti-HBc
IgM anti-HAV
Anti-HEV, HCV, cytomegalovirus, herpes simplex, Epstein-Barr virus
Ceruloplasmin, serum copper, urinary copper, slit-lamp eye examination
Autoantibodies: ANF, ASMA, LKM
Immunoglobulins
Ultrasound of liver and Doppler of hepatic veins
() Hepatitis B core IgM antibody is the best screening test for acute hepatitis B infection, as liver damage is due to the immunological response to the virus which has often been eliminated and the test for HBsAg may be negative.
() The prothrombin time rapidly becomes prolonged as coagulation factor synthesis fails; this is the laboratory test of greatest prognostic value and should be carried out at least twice daily.
() Factor V levels can be used instead of the prothrombin time to assess the degree of liver impairment.
() The plasma bilirubin reflects the degree of jaundice.
() Plasma aminotransferase activity is particularly high after paracetamol overdose, reaching 100-500 times normal, but falls as liver damage progresses and is not helpful in determining prognosis.
() Plasma albumin remains normal unless the course is prolonged.
() Percutaneous liver biopsy is contraindicated because of the severe coagulopathy, but biopsy can be undertaken using the transjugular route.
Adverse prognostic criteria in acute liver failure
()Paracetamol cases
H+ > 50 nmol/L (pH < 7.3) at or beyond 24 hours following the overdose or
Serum creatinine > 300 ?mol/L (? 3.38 mg/dL) plus prothrombin time > 100 seconds plus encephalopathy grade 3 or 4
() Non-paracetamol cases
Prothrombin time > 100 seconds or
Any three of the following:
Jaundice to encephalopathy time > 7 days
Age < 10 or > 40 years
Indeterminate or drug-induced causes
Bilirubin > 300 ?mol/L (? 17.6 mg/dL)
Prothrombin time > 50 seconds
or
Factor V level < 15% and encephalopathy grade 3 or 4
Management
() Patients with acute liver failure should be treated in intensive care unit as soon as progressive prolongation of the prothrombin time occurs or hepatic encephalopathy is identified .
() N-acetylcysteine therapy may improve outcome, particularly in patients with acute liver failure due to paracetamol poisoning.
()Liver transplantation is an increasingly important treatment option for acute liver failure, Survival following liver transplantation for acute liver failure is improving, and 1-year survival rates of about 60% can be expected.
Monitoring in acute liver failure
Neurological
Intracranial pressure monitoring Conscious level
Cardiorespiratory
Pulse Blood pressure
Central venous pressure Respiratory rate
Fluid balance
Hourly output (urine, vomiting, diarrhoea) Input: oral, intravenous
Blood analyses
Arterial blood gases Peripheral blood count (including platelets)
Sodium, potassium, HCO3-, calcium, magnesium Creatinine, urea
Glucose (2-hourly in acute phase) Prothrombin time
Infection surveillance
Cultures: blood, urine, throat, sputum, cannula sites
Chest X-ray
Temperature
Complications of acute liver failure
Encephalopathy and cerebral oedema
Hypoglycaemia
Metabolic acidosis
Infection (bacterial, fungal)
Renal failure
Multi-organ failure (hypotension and respiratory failure)