How to write a Continuous Renal Replacement Therapy (CRRT) prescription?

From the Guidelines

To write a Continuous Renal Replacement Therapy (CRRT) prescription, the dose of RRT should be prescribed before starting each session, with a recommended effluent volume of 20-25 mL/kg/h.

Key Components of a CRRT Prescription

• Modality choice: CRRT is suggested for hemodynamically unstable patients and those with acute brain injury or increased intracranial pressure 1.
• Anticoagulation: Regional citrate anticoagulation is recommended for CRRT in patients without contraindications 1.
• Dialysate and replacement fluid: Bicarbonate is suggested as a buffer in dialysate and replacement fluid for RRT in patients with AKI 1.
• Dose: An effluent volume of 20-25 mL/kg/h is recommended for CRRT in AKI 1.
• Monitoring: Frequent assessment of the actual delivered dose is recommended to adjust the prescription 1.

Considerations for CRRT Prescription

• Patient-specific goals: The prescription should aim to achieve the goals of electrolyte, acid-base, solute, and fluid balance that will meet the patient’s needs 1.
• Individualization: The intensity of CRRT may need to be individualized to meet a patient’s requirements for maintenance of electrolyte and fluid balance 1.
• Quality improvement: Programs should be in place to ensure that delivered doses approximate targets 1.

From the Research

CRRT Prescription Overview

To write a Continuous Renal Replacement Therapy (CRRT) prescription, several factors need to be considered, including:

• CRRT dose: The dose of CRRT is reported as effluent flow in ml/kg body weight per hour (ml/kg/h) 2
• Timing: The timing of CRRT initiation is crucial, and research reveals conflicting evidence for clinicians in distinguishing which patients will benefit from 'watchful waiting' vs. early initiation of CRRT 3
• Fluid management: Precision fluid management using CRRT is difficult to investigate, and currently, only observational data supports individualization of prescriptions 3
• Membrane selection: Individualization of membrane choice is largely experimental 3
• Anticoagulation: The use of anticoagulation in CRRT is important, but the evidence for its use is limited 3
• Vascular access: The choice of vascular access is crucial for the success of CRRT 3

CRRT Dose Calculation

The delivered CRRT effluent dose for critically ill patients with AKI should be 20-25 ml/kg/h on average 2. To account for treatment interruptions and the natural decline in filter efficiency over time, it is recommended to prescribe 25-30 ml/kg/h of effluent dose 2. The calculation of CRRT dose should take into account the patient's weight, fluid status, and solute control needs 4.

CRRT Modalities

There are several CRRT modalities, including:

• Continuous venovenous hemofiltration (CVVH) with predominantly convective solute clearance
• Continuous venovenous hemodialysis (CVVHD) with predominantly diffusive solute clearance
• Continuous venovenous hemodiafiltration (CVVHDF), which combines both dialysis and hemofiltration 5 Each modality has its own advantages and disadvantages, and the choice of modality depends on the patient's specific needs and clinical scenario 5.

Monitoring and Implementation

The prescribed CRRT dose should be systematically monitored and iteratively adjusted in a sustainable mode 6. The implementation of CRRT dose as a quality indicator of CRRT delivery is important to ensure that patients receive the optimal dose of therapy 6, 2.