What are the considerations for using Continuous Renal Replacement Therapy (CRRT) in a patient with acute liver failure due to malignant infiltration and impaired renal function?

CRRT in Acute Liver Failure from Malignant Infiltration

CRRT should be initiated in patients with acute liver failure from malignant infiltration who develop AKI with standard indications (severe electrolyte/acid-base disturbances, refractory volume overload, symptomatic uremia), but only if the patient is a potential liver transplant candidate or has a realistic chance of recovery; otherwise, CRRT serves as futile care in this population with near-universal mortality. 1

Primary Considerations for CRRT Initiation

Transplant Candidacy Assessment

• CRRT is primarily justified as a bridge to liver transplantation in patients with acute liver failure and AKI, as this represents the only definitive treatment with acceptable survival outcomes 1, 2
• For non-transplant candidates with malignant infiltration causing acute liver failure, CRRT should be considered on a case-by-case basis, recognizing the extremely poor prognosis (89-94% mortality) 3, 2
• The 2024 AASLD guidance explicitly states that RRT is not recommended as stand-alone therapy for hepatorenal syndrome-AKI unless patients are transplant candidates 1

Standard Indications for CRRT

CRRT should be initiated when patients develop: 1

• Severe or refractory electrolyte abnormalities (particularly hyperkalemia)
• Refractory acid-base imbalances
• Severe or refractory volume overload unresponsive to medical management
• Symptomatic uremia

Technical Implementation

Modality Selection

• Use continuous RRT rather than intermittent hemodialysis in these patients, as they are typically hemodynamically unstable 1
• CRRT provides superior cardiovascular stability and allows slower correction of severe hyponatremia, reducing neurological complications 1, 4
• Target effluent volume of 20-25 mL/kg/hour 1, 4, 5

Buffer Selection

• Mandatory use of bicarbonate-buffered (not lactate-buffered) dialysate and replacement fluids in liver failure patients 1, 4, 5
• This is a strong recommendation (1B evidence) because patients with liver failure have impaired lactate metabolism, and lactate-buffered solutions risk worsening lactic acidosis 1, 4

Anticoagulation Strategy

• Regional citrate anticoagulation can be used but requires intensive monitoring of ionized calcium levels and total calcium to ionized calcium ratio, as liver failure impairs citrate metabolism 1, 4, 5
• These patients are often coagulopathic from liver failure, making heparin-based anticoagulation potentially hazardous 4
• Consider CRRT with no anticoagulation if citrate is deemed too risky 4, 5

Vascular Access

• Preferred site order: right internal jugular vein, femoral vein, left internal jugular vein 1, 4, 5
• Avoid subclavian vein due to thrombosis/stenosis risk 1, 4, 5
• Always use ultrasound guidance for catheter insertion 1, 5

Critical Prognostic Considerations

Mortality Data

• Hospital mortality for critically ill patients with acute-on-chronic liver failure and AKI requiring CRRT is 89.4%, with only 1.5% ultimately receiving transplantation 3
• Among liver transplant candidates receiving RRT for ARF, only 35% survive to transplant or discharge, with 94% mortality in those not receiving a liver 2
• One-year mortality for patients initiating RRT prior to liver transplant is 30% versus 9.7% for all other liver recipients 2

Prognostic Scoring

• SOFA and CLIF-SOFA scores (AUROC 0.87 and 0.86-0.87 respectively) perform better than MELD or Child-Pugh scores for predicting mortality in this population 3
• Use these scores for repeated risk stratification during treatment to guide ongoing decision-making 1, 3

Management Algorithm

Step 1: Assess Transplant Candidacy

• If patient has malignant infiltration causing acute liver failure, determine if they are a potential transplant candidate
• If not a transplant candidate and no realistic chance of hepatic recovery, strongly consider palliative care rather than CRRT 1

Step 2: Medical Management Before CRRT

• Withdraw diuretics and treat precipitating factors (infection, bleeding) 1
• Administer albumin 1 g/kg (maximum 100 g/day) for 48 hours 1
• For Stage 2 or greater HRS-AKI: initiate vasoconstrictors (terlipressin 0.5-2.0 mg IV q6h or norepinephrine) plus albumin 20-40 g/day 1

Step 3: Initiate CRRT if Medical Management Fails

• Start CRRT when standard indications are met despite medical therapy
• Use bicarbonate-buffered fluids exclusively 1, 4
• Target 20-25 mL/kg/hour effluent volume 1, 4
• Monitor for significant nutrient losses (10-15g amino acids/day) requiring replacement 4

Critical Pitfalls to Avoid

• Do not delay transplant evaluation in patients with HRS-AKI who are potential candidates; refer immediately 1
• Do not use lactate-buffered solutions in liver failure patients under any circumstances 1, 4
• Do not initiate CRRT in non-transplant candidates without frank discussion about the 89-94% mortality rate and goals of care 3, 2
• Do not assume CRRT improves survival in acute liver failure; it serves only as supportive bridge therapy 1, 3, 2
• Monitor for volume overload carefully, as these patients have impaired sodium and water handling 1, 4

Special Consideration for Malignant Infiltration

In the specific context of malignant infiltration causing acute liver failure, the prognosis is particularly grim without transplantation, and transplantation is typically contraindicated due to active malignancy. Therefore, CRRT in this population should generally be avoided unless there is a realistic expectation of tumor response to therapy allowing for hepatic recovery or transplant candidacy. 1, 3