What is the medical management of acute liver failure post cardio pulmonary bypass (cardiopulmonary bypass)?

Medical Management of Acute Liver Failure Post Cardiopulmonary Bypass

Initiate N-acetylcysteine immediately regardless of etiology, provide aggressive hemodynamic support with albumin-based resuscitation and vasopressors, administer empirical broad-spectrum antibiotics at first sign of clinical deterioration, and urgently evaluate for liver transplantation as this is often the only lifesaving option. 1, 2

Immediate Pharmacologic Intervention

N-Acetylcysteine Administration

• Start N-acetylcysteine therapy immediately without waiting for diagnostic confirmation or etiology determination. 1
• NAC improves transplant-free survival (41% vs 30%, P=0.01) and post-transplant survival (85.7% vs 71.4%, P=0.03) in non-acetaminophen acute liver failure. 1, 3
• Standard dosing: continuous infusion for 72 hours minimum. 4
• NAC reduces progression to grade III-IV encephalopathy (51% vs 75%, P<0.05) and mortality (37% vs 63%, P<0.05). 1

Hemodynamic Management

Fluid Resuscitation and Vasopressor Support

• Use albumin (colloid) as first-line fluid resuscitation rather than crystalloid, with all solutions containing dextrose to maintain euglycemia. 2
• Maintain mean arterial pressure ≥50-60 mmHg through aggressive fluid resuscitation first. 2
• If fluid replacement fails, initiate vasopressors: epinephrine, norepinephrine, or dopamine (NOT vasopressin). 2
• Monitor cardiac function closely as right or left ventricular dysfunction can develop post-cardiopulmonary bypass. 1

Adrenal Insufficiency Consideration

• 50% of acute liver failure patients have relative adrenal dysfunction. 1
• Consider hydrocortisone 300 mg per day to reduce vasopressor requirements. 1

Infection Prevention and Treatment

Empirical Antibiotic Therapy

• Administer empirical broad-spectrum antibiotics immediately if there are signs of worsening encephalopathy or systemic inflammatory response syndrome—do not wait for culture results. 1, 2
• Bacterial infections occur in 60-80% of acute liver failure patients; fungal infections occur in one-third. 1, 2
• Cover enterobacteria, staphylococcal, and streptococcal species based on unit ecology. 1

Metabolic and Nutritional Support

Glucose Management

• Monitor blood glucose at least every 2 hours. 1, 2
• Maintain normoglycemia with continuous glucose infusions and insulin therapy as hypoglycemia can mimic hepatic encephalopathy. 1, 2

Electrolyte Management

• Target serum sodium between 140-145 mmol/L. 1
• Hypertonic saline infusion to maintain sodium 145-155 mmol/L significantly decreases intracranial pressure, but avoid levels >150 mmol/L. 1
• Correct sodium abnormalities no faster than 10 mmol/L per 24 hours. 1
• Monitor and correct serum phosphate levels regularly. 1

Airway and Ventilation Management

Intubation Criteria

• Perform tracheal intubation when Glasgow Coma Scale <8. 1
• Use protective mechanical ventilation settings per critical care guidelines. 1
• Avoid high PEEP levels (>10 cmH₂O) due to risk of hepatic congestion. 1

Sedation Strategy

• Avoid benzodiazepines and psychotropic drugs (including metoclopramide). 1
• Use protocol-based sedation to minimize depth and duration. 1
• Exercise caution with dexmedetomidine due to exclusive hepatic metabolism. 1

Encephalopathy Management

Monitoring and Supportive Care

• Monitor encephalopathy grade frequently in patients with high-grade (grades 3-4) encephalopathy. 1
• Ammonia levels >150-200 mmol/L correlate with increased risk of intracranial hypertension. 1
• Do NOT use lactulose or rifaximin to lower ammonia levels—these are not recommended in acute liver failure. 1

Coagulation Management

Restrictive Transfusion Strategy

• Do not routinely correct coagulation abnormalities. 1, 2, 5
• Restrict clotting factor administration to active bleeding or high-risk invasive procedures only. 1, 2

Renal Support

Dialysis Modality

• Use continuous renal replacement therapy rather than intermittent hemodialysis if dialysis is required. 2

Additional Supportive Measures

Stress Ulcer Prophylaxis

• Provide stress ulcer prophylaxis with H2 blockers or proton pump inhibitors in this high-risk population. 1, 2

Thromboprophylaxis

• Start low molecular weight heparin or unfractionated heparin postoperatively unless exceptional contraindications exist. 2
• Add intermittent pneumatic compression devices to further decrease thrombotic risk. 2

Liver Transplantation Evaluation

Urgent Transplant Assessment

• Evaluate urgently for liver transplantation as this is often the only lifesaving option, particularly when transplant-free survival is <25%. 1, 2
• Post-transplant survival rates for acute liver failure are 80-90%. 2
• Early referral to a transplant center is critical as the "transplantation window" is often narrow. 2

Prognostic Indicators

• King's College criteria: pH <7.3, prothrombin time >100 seconds, creatinine >300 μmol/L, encephalopathy grade >3. 1
• Lactate >3.5 mmol/L at 4 hours or >3.0 mmol/L at 12 hours after volume resuscitation indicates poor prognosis. 1
• Factor V levels <20%, vasopressor requirement with organ failure, ammonia >100 μmol/L, or bilirubin >140-200 μmol/L suggest poor outcome. 1

Critical Pitfalls to Avoid

• Do not delay empirical antibiotics while awaiting culture results—infection is the most common precipitant. 2
• Do not use growth factors for leukopenia—there is no evidence for this approach. 2
• Do not use nephrotoxic drugs including NSAIDs. 5
• Do not delay transfer to a liver transplantation center. 1
• Avoid liver support devices as they have not demonstrated mortality reduction and should not delay transplant evaluation. 1