What is the recommended protocol for initiating Continuous Renal Replacement Therapy (CRRT) in patients with Impaired renal function?

Initiating Continuous Renal Replacement Therapy (CRRT) Protocol

For patients with acute kidney injury requiring CRRT, deliver an effluent volume of 20-25 mL/kg/h using bicarbonate-buffered replacement fluid, with regional citrate anticoagulation as first-line therapy in patients without citrate contraindications. 1

Vascular Access Establishment

Place an uncuffed nontunneled dialysis catheter using ultrasound guidance with the following site preference order: 1, 2

• First choice: Right internal jugular vein
• Second choice: Femoral vein
• Third choice: Left internal jugular vein
• Last choice: Subclavian vein (avoid due to thrombosis and stenosis risk) 3, 2

Obtain a chest radiograph immediately after placement and before first use for internal jugular or subclavian catheters. 1, 2

Ensure adequate catheter length to minimize access recirculation and malfunction. 1

Anticoagulation Selection Algorithm

Step 1: Assess bleeding risk and coagulation status 1, 2

Step 2: Select anticoagulation based on risk profile:

For patients WITHOUT increased bleeding risk:

• Use regional citrate anticoagulation (preferred over heparin) 1, 3, 2
• If citrate contraindicated: Use unfractionated or low-molecular-weight heparin 1, 2

For patients WITH increased bleeding risk:

• Use regional citrate anticoagulation if no citrate contraindications 1, 2
• Avoid regional heparinization 1

For patients with heparin-induced thrombocytopenia (HIT):

• Stop all heparin immediately 1
• Use direct thrombin inhibitors (argatroban) or Factor Xa inhibitors (danaparoid, fondaparinux) 1, 2
• Prefer argatroban in patients without severe liver failure 1

CRRT Dosing Prescription

Prescribe 20-25 mL/kg/h of effluent volume before starting each CRRT session. 1, 3, 2, 4 This represents the delivered dose target; prescribe higher to account for downtime and circuit issues. 1

Frequently assess the actual delivered dose and adjust the prescription to maintain target. 1, 2

The RENAL and ATN trials demonstrated no mortality benefit with higher doses (35-40 mL/kg/h vs 20-25 mL/kg/h), establishing 20-25 mL/kg/h as the evidence-based standard. 1

Fluid Composition Selection

Use bicarbonate-buffered (not lactate-buffered) dialysate and replacement fluid for all patients. 1, 3, 2, 4 This is a strong recommendation (1B) for patients with circulatory shock and a suggestion (2B) for those with liver failure or lactic acidemia. 1

The increased availability of commercially prepared bicarbonate-based CRRT fluids supports their use as the buffer of choice. 1

Ensure all dialysis fluids comply with AAMI standards for bacterial and endotoxin contamination. 1, 2

Filter and Membrane Selection

Use dialyzers with biocompatible membranes (standard surface area 0.9-1.5 m² for most adults). 1, 3, 2

Avoid unsubstituted cellulosic membranes, which are associated with increased mortality (RR 1.23). 5

Modality Selection Based on Clinical Status

Use CRRT rather than intermittent hemodialysis for: 1, 2, 4

• Hemodynamically unstable patients requiring vasopressor support (2B recommendation)
• Patients with acute brain injury or increased intracranial pressure (2B recommendation)
• Patients with generalized brain edema (2B recommendation)

CRRT and intermittent RRT produce similar mortality outcomes overall (RR 1.10,95% CI 0.99-1.23), but CRRT provides superior hemodynamic tolerance in unstable patients. 1, 5

Monitoring and Dose Adjustment

Monitor continuously: 3, 2, 4

• Filter performance and circuit pressures
• Electrolyte balance (especially calcium, magnesium, phosphate with citrate)
• Acid-base status
• Fluid balance and net ultrafiltration achieved
• Actual delivered effluent volume vs. prescribed

Adjust prescription dynamically based on changing clinical needs, solute control targets, and circuit downtime. 6

Critical Pitfalls to Avoid

Do NOT: 1, 2

• Use topical antibiotics at catheter insertion sites 1, 2
• Use antibiotic locks for infection prevention in nontunneled catheters 1, 2
• Rely solely on single BUN/creatinine thresholds to initiate RRT 1, 2
• Use lactate-buffered solutions in patients with liver failure or lactic acidosis 1, 2
• Use subclavian access except as last resort 3, 2

Transitioning from CRRT

Consider transitioning to intermittent hemodialysis when: 1, 4

• Vasopressor support has been discontinued
• Hemodynamic stability achieved
• Intracranial hypertension resolved (if applicable)
• Positive fluid balance controllable by intermittent hemodialysis

Discontinue RRT when kidney function has recovered (sustained independence from RRT for minimum 14 days) or when RRT becomes inconsistent with shared care goals. 1, 4