Renal Replacement Therapy in Critically Ill Patients

Modality Selection

The American Journal of Kidney Diseases recommends using continuous renal replacement therapy (CRRT) rather than intermittent hemodialysis for hemodynamically unstable ICU patients with acute kidney injury, prioritizing CRRT for patients with acute brain injury, increased intracranial pressure, or cerebral edema 1, 2
CRRT provides superior hemodynamic stability through slower, more gradual fluid and solute shifts compared to intermittent modalities, and is preferred for hemodynamically unstable patients 1, 2

The American Journal of Kidney Diseases recommends delivering an effluent volume of 20-25 mL/kg/hour for CRRT in AKI patients, with frequent assessment of actual delivered dose to adjust the prescription 1, 2
The prescribed dose must be documented before each session, with systematic monitoring of delivered versus prescribed dose as a quality indicator 1
Adjust the prescription iteratively to achieve goals of electrolyte balance, acid-base correction, solute control, and fluid management 1, 2

The American Journal of Kidney Diseases recommends using regional citrate anticoagulation as first-line for CRRT in patients without contraindications, rather than heparin-based anticoagulation 1, 2
Regional citrate is preferred over heparin for CRRT (2B evidence) in patients without increased bleeding risk or existing anticoagulation 1, 2
In patients with increased bleeding risk, still use regional citrate anticoagulation rather than no anticoagulation during CRRT if no citrate contraindications exist 1, 2

The American Journal of Kidney Diseases recommends using bicarbonate rather than lactate as the buffer in all dialysate and replacement fluids for critically ill patients, particularly those with circulatory shock, liver failure, or lactic acidemia 1, 2, 4
Bicarbonate is strongly recommended (1B evidence) for patients with circulatory shock due to impaired lactate metabolism 1, 2
Bicarbonate is also recommended (2B evidence) for patients with liver failure and/or lactic acidemia to prevent worsening metabolic acidosis 1, 2, 4

The American Journal of Kidney Diseases recommends inserting dialysis catheters using ultrasound guidance via an uncuffed nontunneled catheter, with the right internal jugular vein as first choice 1, 2
Vein selection hierarchy: (1) right internal jugular, (2) femoral, (3) left internal jugular, (4) subclavian (last choice, preferably dominant side) 1, 2
Obtain chest radiograph promptly after internal jugular or subclavian placement before first use 1, 2

The American Journal of Kidney Diseases recommends using dialyzers with biocompatible membranes for both intermittent hemodialysis and CRRT in AKI patients 1, 2
Biocompatible membranes reduce inflammatory activation and complement activation compared to cellulose-based membranes 1, 2

The Kidney International recommends initiating RRT before the development of life-threatening complications in critically ill patients, rather than waiting for conventional thresholds 5
Start RRT prior to development of diuretic-unresponsive pulmonary edema, severe hyperkalemia, or uremic complications, as consequences are more severe in critically ill patients 5
Base decisions on comprehensive clinical evaluation rather than specific BUN or creatinine thresholds 6
The rate of increase of azotemia is more important than absolute values 6

Patients on CVVHF require higher protein intake (1.5-1.7 g/kg/day) compared to SLED (1.3-1.5 g/kg/day) due to continuous amino acid losses 3
Monitor for significant losses of water-soluble vitamins, amino acids (10-15g/day), and electrolytes (phosphate, magnesium) during CRRT 4