12.3 Pediatric Acute Liver Failure, Hepatic Encephalopathy & Abdominal Compartment Syndrome

Pediatric acute liver failure and abdominal compartment syndrome

Recognize acute liver failure and refer early

Pediatric acute liver failure (PALF) combines biochemical evidence of acute liver injury, no known preexisting chronic liver disease and hepatic coagulopathy that persists after appropriate parenteral vitamin K. The PALF Study Group framework uses an INR of at least 1.5 (or PT at least 15 seconds) with hepatic encephalopathy, or an INR of at least 2.0 (or PT at least 20 seconds) regardless of whether encephalopathy is apparent. In infants and toddlers, irritability, poor feeding or a change in interaction may be the first signs. The PODIUM critical-care framework specifies an acute illness under eight weeks. An elevated INR by itself has other causes. Interpret the result alongside the acute injury, timing, vitamin K response and clinical findings. Markedly elevated aminotransferases are not required in every cause. Contact a pediatric liver transplant center early as you stabilize and investigate. NASPGHAN PALF position paper · PODIUM liver dysfunction criteria · 2026 pediatric transplant evaluation guideline

Check glucose immediately and follow coagulation, ammonia, bilirubin, aminotransferases, electrolytes, acid-base status and kidney function. Support perfusion and glucose while avoiding unnecessary fluid accumulation. Use age- and weight-appropriate parenteral vitamin K and recheck PT/INR. Avoid routinely giving plasma to normalize the INR. INR reflects hepatic synthetic dysfunction and does not independently predict bleeding. Discuss replacement for active significant bleeding or a planned invasive procedure with the treating team. NASPGHAN PALF position paper

Investigate causes while starting time-critical therapy

The chart uses the first 348 PALF Study Group patients. Indeterminate disease accounted for 169/348, about 49%, and acetaminophen for 48/348, about 14%. These are cohort observations. Continue age-directed evaluation when the cause is uncertain. Original PALF cohort · NASPGHAN PALF position paper · CDC neonatal HSV guidance · Pediatric Wilson cohort

Use acetylcysteine according to the exposure and response

In overdose, the reactive acetaminophen metabolite NAPQI can exhaust glutathione and injure hepatocytes. Acetylcysteine (NAC) supports glutathione repletion. For an acute oral exposure with reliable timing, use the revised Rumack–Matthew nomogram with a sample drawn 4–24 hours after ingestion began. Treat at or above the time-specific treatment line, which starts at 150 µg/mL at four hours. Unknown timing, repeated supratherapeutic exposure over more than 24 hours and late presentation require separate clinical and laboratory assessment. Use poison-center guidance for delayed absorption. With strong concern for a toxic ingestion, start NAC if waiting for testing would delay treatment beyond eight hours. Start while evaluating suspected acetaminophen-associated liver injury even when the late concentration is low. U.S./Canada consensus

The U.S. ACETADOTE label's three-bag IV regimen gives 150 mg/kg over one hour, 50 mg/kg over four hours, and 100 mg/kg over 16 hours, for 300 mg/kg over 21 hours. Use labeled weight-based dilution and review volume in small children. The label uses the three-bag regimen in patients weighing 5–40 kg and offers a two-bag option from 41 kg. With ongoing injury, consult toxicology and reassess near the end of the planned course. The 2026 ACMT criteria for stopping IV NAC include all of the following: acetaminophen below 10 µg/mL, AST/ALT at baseline or falling 25–50% from their peak if elevated, INR below 2.0 and improving relevant prognostic markers such as creatinine, lactate, pH or phosphate. If criteria are unmet, continued infusion at 6.25 mg/kg/h can be appropriate with toxicology guidance. U.S. ACETADOTE label · ACMT 2026 stopping criteria

Once a non-acetaminophen cause is established, routine NAC lacks demonstrated pediatric survival benefit. In a pediatric placebo-controlled trial, one-year overall survival was similar and transplant-free survival was 35% with NAC versus 53% with placebo. The adult early-encephalopathy result cannot be applied to children. Pediatric randomized trial

Reassess encephalopathy, cerebral edema and renal support

Trend mental status and the neurologic examination. Early changes include sleep, attention or behavior changes. Lethargy and confusion can progress to stupor (grade III) and coma (grade IV). Use age-appropriate signs and assess competing causes, including hypoglycemia, infection, sedatives and seizures. Check EEG when seizure or unexplained deterioration is suspected. Ammonia contributes to astrocytic swelling through glutamine accumulation, alongside inflammatory and other mechanisms. Levels above 200 µmol/L have been associated with herniation risk. A single value does not establish encephalopathy or determine treatment. NASPGHAN PALF position paper

• Protect the brain and airway. Elevate the head about 30° with the neck neutral when feasible. Avoid hypoxemia, hypotension, fever and routine hyperventilation. Plan airway protection for high-grade encephalopathy or loss of protective reflexes. New pupil asymmetry, posturing or rapidly worsening consciousness warrants immediate neurocritical care. Choose hypertonic saline or mannitol for suspected intracranial hypertension with specialist guidance, taking sodium, hemodynamics and renal function into account. Invasive ICP monitoring is case-specific because of bleeding risk and uncertain outcome benefit.
• Discuss early continuous clearance. Significant or rising ammonia with worsening encephalopathy or AKI should prompt early nephrology and transplant consultation. The PCRRT PALF position paper lists uncontrolled ammonia above 150 µmol/L or ammonia above 200 µmol/L among findings supporting KRT assessment. Consider other indications and the trajectory. Continuous KRT can limit hemodynamic and osmotic shifts when cerebral edema is a concern. Individualize circuit anticoagulation. A high INR alone cannot choose the circuit strategy. Lactulose has uncertain outcome benefit in PALF. Inborn errors of metabolism use separate clearance guidance. NASPGHAN PALF position paper · PCRRT PALF position paper

Separate prognosis, referral and allocation

Refer promptly for transplant evaluation and follow changes in INR, bilirubin, ammonia, encephalopathy and organ support. King's College criteria provide prognostic context. In one validation for non-acetaminophen PALF, sensitivity was 61% and specificity 70% for death among children assessed without transplantation. Prognostic scores cannot determine listing by themselves.

The peak LIU-INR score uses $3.507B + 45.51I + 0.254A$, where $B$ is peak total bilirubin in mg/dL, $I$ is peak INR, and $A$ is peak ammonia in µmol/L. The original PT-based version uses different coefficients and PT in seconds. With peak bilirubin 8 mg/dL, INR 3.0 and ammonia 150 µmol/L, LIU-INR is approximately 203. This summarizes peak laboratory severity. It cannot assign waitlist priority. Pediatric King's College validation · LIU-INR derivation · Multinational LIU study

U.S. OPTN Policy 9.1.B governs pediatric liver Status 1A. For its fulminant liver failure pathway, candidates must be younger than 18 at registration and have no preexisting liver disease diagnosis as defined by the policy. Qualifying findings include ventilator dependence, a listed form of dialysis or continuous KRT, INR 1.5 to below 2.0 with hepatic encephalopathy diagnosed within 56 days of first liver symptoms, or INR at least 2.0. Acute decompensated Wilson disease has a separate criterion. The transplant program determines candidacy and submits the justification form. Do not wait for allocation eligibility or a score before referral. 2026 transplant evaluation guideline · OPTN Policy 9.1.B

Measure and treat elevated intra-abdominal pressure

Risk rises after major resuscitation, trauma, abdominal operations, peritonitis or marked visceral edema. A tense abdomen, falling urine output, worsening ventilation or circulatory compromise warrants assessment. These findings are nonspecific. Look for bleeding, ongoing infection and other causes of deterioration in parallel.

Use a drained bladder and 1 mL/kg sterile saline, with a 3 mL minimum and 25 mL maximum. Measure in mmHg, supine and at end-expiration, with the abdominal muscles relaxed and the transducer zeroed at the midaxillary line. For a 16 kg child, the instillate is 16 mL. Confirm technique and trend pressure with organ function. Elevated pressure can impair venous return and renal function and push the diaphragm upward, reducing respiratory compliance. Abdominal perfusion pressure is MAP minus IAP. WSACS gives no pediatric resuscitation target based on that calculation. WSACS pediatric definitions and management

For overt ACS, contact surgery urgently while maintaining perfusion and addressing the cause. Appropriate immediate measures may include gastric or bowel decompression, adequate analgesia and sedation, and image-guided drainage of accessible fluid when suitable. After necessary resuscitation, minimize avoidable fluid accumulation. Do not delay definitive decompression in a deteriorating child. Overt ACS can require prompt decompressive laparotomy, with open-abdomen care directed by surgery. Paralysis, diuresis or KRT may be considered selectively and cannot replace source control or needed decompression. WSACS pediatric management statements