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Table 9.2a. Hepatic encephalopathy

Stage 1 Slowing of consciousness

Stage 2 Drowsiness

Stage 3 Confusion, reactive only to vocal stimuli

Stage 4 Presence of deep coma with absence of reaction to vocal stimuli

Table 9.2b. Grading of coma in stages 3 and 4

Grade 1 Reactivity to vocal stimuli

Grade 2 Absence of reactivity to vocal stimuli, but with a coordinated response to painful stimuli Grade 3 Absence of reactivity to vocal stimuli with a incoordinated response to painful stimuli Grade 4 Brain death

It is essential that these patients be admitted and monitored closely in a specialized liver unit where frequent surveillance of their LFTs, PT, CBC, blood gases, blood sugars, electrolytes, and neurological status is performed. With Tylenol overdose, liver transplantation can be prevented if therapy is initiated early. With progression of encephalopathy to stage 3 or 4, the patient should be intubated for airway protection, as these patients have a very high incidence of aspiration as they deteriorate neurologically. An NG tube should be placed at this time and lactulose initiated. The patient should be started on an H2-blocker to prevent ulceration. A Foley catheter should be placed, as well as an arterial line. Central venous monitoring should be entertained if there is a deterioration in renal function or hemodynamic instability. An intracranial pressure monitor should be placed if the patient's neurologic status cannot be followed clinically, in order to accurately assess progressive brain swelling.4 Cerebral perfusion pressures determined by subtracting the intracranial pressure from the mean arterial pressure provides a marker for cerebral perfusion. In the case of sustained untreatable cerebral hypoperfusion, the patient may no longer be considered a transplant candidate since irreversible brain injury may occur. If there is evidence of ongoing brain swelling, hyperventilation and/or mannitol may help temporarily.

Prior to the availability of liver transplantation, many non-surgical approaches were attempted in patients with acute liver failure including exchange transfusions, steroids, hemodialysis, and charcoal hemoperfusion. Unfortunately, none of these approaches have been particularly successful. There is new evidence that hypothermia may help to delay brain swelling which is often the terminal complication, but further assessment of this approach is needed. Presently, liver transplantation is considered the best therapeutic option for acute liver failure not thought to be reversible. The criteria for determining whether a patient will need liver transplant or not include factor V level less than 30%, pH less than 7.3%, INR >6.5, stage 3 or 4 encephalopathy, and lack of response to medical therapy within 20 to 48 hours.(Table 9.3)

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