Acute Liver Failure and Hepatic Encephalopathy
≥1.5
INR Threshold
ALF diagnostic criterion
2-4
Lactulose Target
Bowel movements per day
#1
Acetaminophen
Most common cause in the US
Acute Liver Failure Definition
all four criteria must be presentCoagulopathy (INR ≥1.5)
Hepatic encephalopathy (any grade)
No prior liver disease (or recognition of liver disease <26 weeks)
Duration less than 26 weeks from onset of symptoms
Most Common Causes
Acetaminophen#1 in the US
Viral hepatitisHep A, B (not C acutely)
Drug-inducedAntibiotics, anticonvulsants
Autoimmune hepatitisImmune-mediated
Wilson diseaseCopper accumulation
IschemicShock liver
Hepatic Encephalopathy
Ammonia accumulates when the liver cannot convert it to urea. It crosses the blood-brain barrier and causes progressive neurological dysfunction.
Grade I
Mild confusion, altered sleep, difficulty concentrating
Grade II
Lethargy, disorientation, asterixis (liver flap) present
Grade III
Somnolent but arousable, marked confusion, incoherent speech
Grade IV
Coma, unresponsive, may have decerebrate posturing
Asterixis is the hallmark sign. A flapping tremor of the extended wrists caused by intermittent loss of muscle tone. Classic for Grade II.
Treatment is lactulose (2-4 BMs/day) and rifaximin (reduces ammonia-producing gut bacteria). Monitor ammonia levels but treat clinically, not just by the number.
N-Acetylcysteine (NAC) Protocol
NAC is the antidote for acetaminophen toxicity. It replenishes glutathione, the liver's primary detoxification molecule. Most effective within 8 hours of ingestion but can still benefit up to 24-72 hours.
Do NOT correct INR prophylactically. It is the single best prognostic indicator. Correcting it masks progression. The trend of the INR tells you whether the liver is recovering or deteriorating.
Key Values to Memorize
ALF INR ≥1.5
Lactulose 2-4 BMs/day
NAC within 8 hrs ideal
Acetaminophen = #1 cause
Asterixis = Grade II
Grade IV = coma
liver failure management is all about what NOT to do
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Practice CCRN QuestionsExam Traps
Do NOT correct INR unless the patient is actively bleeding or needs a procedure
The INR is the single best prognostic indicator in acute liver failure. Correcting it with FFP or PCC masks disease progression and removes your most valuable monitoring tool. Only correct for active hemorrhage or before an invasive procedure.
Lactulose target is 2-4 bowel movements per day, not just one
Under-dosing lactulose leaves ammonia elevated. The target is 2-4 soft BMs per day. However, over-dosing causes severe diarrhea leading to dehydration, electrolyte imbalances, and potentially worsening encephalopathy through metabolic derangements.
Too much lactulose causes dehydration and electrolyte chaos
Excessive lactulose leads to profuse diarrhea, hypovolemia, hypernatremia, and metabolic alkalosis. The patient can become MORE confused from the metabolic derangements than they were from the ammonia. Titration is key.
INR is Your Crystal Ball
The INR is your prognostic crystal ball. Correcting it with FFP just fogs the glass. Only correct for active bleeding or before a procedure.
Lactulose Sweet Spot
Lactulose: titrate to 2-4 soft BMs per day. Too little = ammonia rises. Too much = dehydration and electrolyte chaos.
The liver is the body's main factory. It produces clotting factors, metabolizes drugs, filters toxins (like ammonia), and makes bile. When the factory shuts down, everything it was supposed to process starts accumulating.
Acute liver failure is a sudden factory closure. Toxins pile up (ammonia → encephalopathy), products stop being made (clotting factors → coagulopathy, INR rises), and waste backs up everywhere.
The INR is like the factory's daily quality report. It tells you exactly how badly the factory is performing. If you artificially fix the report (give FFP), you no longer know how the factory is actually doing. The report becomes useless for tracking whether the factory is recovering or getting worse.
Lactulose is the cleanup crew for ammonia. It converts ammonia into a form that exits through stool. But if the cleanup crew works too hard (too much lactulose), they cause their own mess (dehydration, electrolyte problems). You need just the right amount of cleanup.
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