++
Liver failure is defined in adults by the requisite hallmarks
of the presence of hepatic encephalopathy and uncorrectable coagulopathy
within 8 weeks of the development of clinical jaundice, in the absence of
known preexisting chronic liver disease. In children, a modified
working definition for pediatric acute liver failure has been achieved
by consensus of an expert panel (the Pediatric Acute Liver Failure [PALF] Study
Group) as follows:
++
1. No known evidence of chronic liver disease.
2. Biochemical evidence of acute liver injury.
3. Hepatic-based uncorrectable coagulopathy defined as an international
normalized ratio (INR) greater than or equal to 1.5 (approximate
to a prothrombin time [PT] ⩾ 15 sec) in the presence
of clinical hepatic encephalopathy OR (3a) an INR ⩾ 2.0 (approximate
to PT ⩾ 20 sec) without hepatic encephalopathy.1
++
These modifications to the definition for pediatric acute liver
failure notably recognize the difficulty of detecting hepatic encephalopathy, particularly
the earlier stages, in infants and small children; markers of liver
synthetic failure, such as an uncorrectable coagulopathy, as important
indicators of liver failure even in the absence of hepatic encephalopathy;
and children presenting in acute liver failure may in fact have
a chronic liver condition not previously suspected or known. A clinical
coma grade scale has been adapted for infants and children under
the age of 4 years (Table 424-1).2
++
++
The approach to the child with acute liver failure should include
the following: (1) establishment of an accurate diagnosis; (2) provision of
intense, comprehensive medical supportive therapy; (3) anticipation,
prevention, and timely treatment of complications, which may preclude
the realization of spontaneous recovery; and (4) early referral
to a liver transplant center, prior to the onset of complications
of multiorgan failure, to assess both for indications and contraindications
to liver transplantation. The causes of acute liver failure in children
include a variety of age-dependent etiologies (Table
424-2). The diagnostic evaluations for these disorders is discussed
elsewhere.
++