What is the role of albumin (human albumin) in large volume paracentesis to prevent hypotension and impaired renal function?

Role of Albumin in Large Volume Paracentesis

Albumin should be administered at a dose of 6-8 g per liter of ascitic fluid removed during large volume paracentesis (>5 liters) to prevent post-paracentesis circulatory dysfunction, renal impairment, and hyponatremia. 1, 2

Pathophysiology and Rationale

Large volume paracentesis (LVP) causes significant hemodynamic changes:

• Marked reduction in intra-abdominal and inferior vena cava pressure
• Decrease in right atrial pressure
• Initial increase in cardiac output
• Subsequent decrease in pulmonary capillary wedge pressure
• Risk of post-paracentesis circulatory dysfunction (PPCD) 1

Without plasma expansion, these changes can lead to:

• Activation of the renin-angiotensin-aldosterone system
• Renal impairment
• Hyponatremia
• Increased mortality 1

Evidence-Based Recommendations

Volume Threshold for Albumin Administration

• For paracentesis >5 liters: Albumin administration is strongly recommended 1, 2
• For paracentesis <5 liters: Plasma expansion is generally not necessary unless the patient has acute-on-chronic liver failure (ACLF) 1

Albumin Dosing

• Recommended dose: 6-8 g of albumin per liter of ascites removed 1, 2
• Administration timing: After paracentesis is completed 1, 2
• Example calculation: For 8 liters of ascitic fluid removed, administer 64 g of albumin (equivalent to 320 ml of 20% albumin solution or 256 ml of 25% albumin solution) 1, 2

Clinical Benefits of Albumin

Meta-analyses have demonstrated that albumin administration, compared to alternative treatments or no treatment:

• Reduces PPCD by 61% (OR = 0.39,95% CI 0.27-0.55) 2
• Decreases hyponatremia by 42% (OR = 0.58,95% CI 0.39-0.87) 2, 3
• Lowers mortality by 36% (OR = 0.64,95% CI 0.41-0.98) 2, 3

Albumin vs. Alternative Plasma Expanders

While some studies suggest that artificial plasma expanders (dextran, gelatin, hydroxyethyl starch) may be clinically effective, albumin remains superior for several reasons:

• Less activation of the renin-angiotensin-aldosterone system 1
• Lower incidence of hyponatremia (8% vs 17%) 1
• Better prevention of PPCD 4, 3
• Many alternative plasma expanders have been restricted due to safety concerns (prion transmission, allergic reactions, renal impairment) 1

A direct comparison study showed midodrine was not as effective as albumin in preventing circulatory dysfunction, with higher rates of renal failure and mortality in the midodrine group 5.

Practical Considerations

• Volume limitation: Consider limiting paracentesis to <8 liters per session, as the risk of PPCD increases with larger volumes 1
• Procedure technique: Use ultrasound guidance when available to reduce adverse events 1
• Cost considerations: While albumin is more expensive than alternatives, it may reduce overall hospital costs by decreasing liver-related complications 1
• Standardized protocols: Implementation of standardized order sets for albumin dosing can reduce albumin usage without compromising patient outcomes 6

Common Pitfalls to Avoid

1. Underdosing albumin: Insufficient albumin replacement can lead to PPCD and associated complications
2. Omitting albumin for LVP >5 liters: This significantly increases risk of renal dysfunction and hyponatremia
3. Performing repeated small-volume paracentesis: This offers no benefits and increases procedure-related complications 1
4. Delaying diuretic reintroduction: Diuretics should be reintroduced within 1-2 days after paracentesis to prevent ascites recurrence 1

By following these evidence-based recommendations, clinicians can minimize the hemodynamic complications associated with large volume paracentesis and improve patient outcomes.