Slow continuous ultrafiltration and prolonged intermittent renal replacement therapy: Tailoring renal replacement therapy in intensive care unit

Table 1 Comparative table of renal replacement therapy modalities

Characteristic	CRRT (CVVH/CVVHD/CVVHDF)	SCUF	PIRRT (CRRT platforms)	SLED	SLEDD-F
Full name/concept	Continuous renal replacement therapy	Slow continuous ultrafiltration	Prolonged intermittent RRT (via CRRT machines)	Sustained low-efficiency dialysis	Sustained low-efficiency daily dialysis with filtration
Typical session duration	24 hours/day	12-24 hours/day	6-12 hours/session	6-12 hours/session	6-12 hours/session
Blood flow rate	Approximately 100-200 mL/minute	Approximately 50-150 mL/minute	Approximately 150-250 mL/minute	Approximately 150-250 mL/minute	Approximately 150-250 mL/minute
Dialysate/effluent rate	Effluent 20-35 mL/kg/hour	None; ultrafiltration 100-500 mL/hour	20-25 mL/kg/hour	Dialysate approximately 100-300 mL/minute	As in SLED + convective filtration
Predominant clearance mechanism	Diffusion/convection mixed	Convection (volume removal)	Mixed diffusive/convective	Diffusion	Diffusion + Convection
Hemodynamic profile	Best tolerated in unstable patients	Very well tolerated	Intermediate tolerance	Intermediate tolerance	Similar to SLED; slightly higher impact
Primary clinical indication	AKI with hemodynamic instability	Refractory fluid overload	Hybrid/step-down therapy	AKI in ICU where extended sessions feasible	AKI requiring enhanced solute clearance
Equipment	Continuous RRT machines	Continuous RRT machines	CRRT machines	Hemodialysis machines	Hemodialysis machines with HDF capability

This table compares major renal replacement therapy modalities used in the intensive care unit, highlighting differences in treatment duration, equipment, hemodynamic tolerance, and solute/fluid clearance mechanisms. Continuous renal replacement therapy modalities provide continuous support for unstable patients, while sustained low-efficiency dialysis, sustained low-efficiency daily dialysis with filtration, and prolonged intermittent renal replacement therapy represent extended intermittent therapies with varying diffusive and convective components. Slow continuous ultrafiltration is a fluid-focused modality with minimal solute removal. CRRT: Continuous renal replacement therapy; CVVH: Continuous veno-venous hemofiltration; CVVHD: Continuous veno-venous hemodialysis; CVVHDF: Continuous veno-venous hemodiafiltration; SCUF: Slow continuous ultrafiltration; PIRRT: Prolonged intermittent renal replacement therapy; SLED: Sustained low-efficiency dialysis; SLEDD-F: Sustained low-efficiency daily dialysis with filtration; RRT: Renal replacement therapy; AKI: Acute kidney injury; ICU: Intensive care units; HDF: Hemodiafiltration.