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

Table 4 Standardized sustained low-efficiency dialysis prescription

Standardized SLED prescription
Modality	SLED also known as: Extended daily dialysis, slow extended daily dialysis
Indication	Acute kidney injury kidney disease: Improving Global Outcomes stage 3 with hemodynamic instability or inability to tolerate standard intermittent hemodialysis. Alternative to CRRT when continuous therapy not required
Duration/frequency	8-12 hours per session, daily or 6 times per week (adjust based on clinical needs: 6-16 hours possible) typical: 10 hours nocturnal (allows daytime mobilization)
Machine	Standard hemodialysis machine (conventional dialysis equipment) advantage: No need for dedicated CRRT machines
Blood flow	250 mL/minute (range: 200-300 mL/minute) lower than conventional HD (350-450 mL/minute), higher than CRRT (150-200 mL/minute)
Dialysate flow	200 mL/minute (range: 100-300 mL/minute) much lower than conventional HD (500-800 mL/minute). This is the key parameter that defines ‘low-efficiency’
Dialysate temperature	35.5-36.5 °C (cooler than standard 37 °C) improves hemodynamic tolerance and reduces hypotension
Ultrafiltration rate	According to fluid balance goals (typical 100-400 mL/hour) for 10 hours session: 1-4 L net removal maximum recommended: 500 mL/hour if tolerated
Sodium profile	Optional: Start 145 mEq/L, taper to 140 mEq/L improves hemodynamic stability standard: Fixed 140 mEq/L acceptable
Ultrafiltration profile	Optional: Higher rate in first half, lower in second half example: 300 mL/hour × 5 hours to 200 mL/hour × 5 hours reduces hypotension risk
Anticoagulation	Option 1: Heparin - activated partial thromboplastin 45-60 sec or anti-Xa 025-0.35 U/mL. Bolus: 1000-2000 units. Maintenance: 500-1000 units/hour. Option 2: Regional citrate anticoagulation (if available). Option 3: None - if contraindicated (frequent saline flushes every 30 minutes)
Vascular access	Double-lumen dialysis catheter (11.5-14 Fr) preferred sites: Internal jugular > femoral > subclavian can use existing chronic HD access (fistula/graft) if available
Dialyzer	High-flux dialyzer, surface area 18-2.1 m2 biocompatible membrane (polysulfone, polyethersulfone, polyamix) standard dialysis filters (not hemofilters)
Dialysate composition	Standard composition: Na+ 140 mEq/L (or profiled 145 to 140); K+ 2-3 mEq/L (adjust based on serum K+: 0-1 mEq/L if K+ > 6.0). Ca2+ 2.5-3.0 mEq/L, Mg2+ 1.0 mEq/L, bicarbonate 32-35 mEq/L, glucose 100-200 mg/dL
Treatment time calculation	Target weekly Kt/V: ≥ 3.0-3.6 for daily SLED standard urea kinetic modeling: For daily 10 hours SLED at blood flow 250, dialysate flow 200: Single session Kt/V approximately 1.0-1.2 weekly Kt/V (6 sessions) approximately 6.0-7.2 (adequate), alternate day SLED: May need longer sessions (12 hours)
Monitoring	During treatment: Blood pressure: Every 15-30 minutes, intradialytic hypotension protocol ready, fluid balance: Hourly, access pressures: Continuous, clinical assessment: Every 2 hours, laboratory: Electrolytes: Pre-treatment, post-treatment, blood gas/pH: Pre and post-treatment, BUN, creatinine: Daily, CBC: Every 2-3 days
Advantages vs conventional IHD	Better hemodynamic tolerance (50%-70% less hypotensive episodes). More gradual solute and fluid removal. Less osmotic shifts (reduced dialysis disequilibrium). Reduced risk of arrhythmias. Better preservation of residual renal function. Allows higher total UF without hemodynamic compromise
Advantages vs CRRT	50%-60% cost reduction (less fluid consumption, standard machines). Nurse not dedicated 24 hours (typically nocturnal treatment). Allows daytime mobilization and rehabilitation. Easier nursing care (familiar equipment). No need for specialized CRRT equipment. Adequate clearance for most acute kidney injury cases
Adjustments	Increase efficiency if: Persistent azotemia (BUN > 80-100 mg/dL), hyperkalemia (K+ > 5.5 mEq/L), severe metabolic acidosis → increase dialysate flow to 250-300 mL/minute or increase session length to 12 hours. Decrease intensity if: Hemodynamic instability, intradialytic hypotension (> 2 episodes/session) → decrease dialysate flow to 100-150 mL/minute or decrease UF rate or use profiling
Hypotension management	Prevention: Cool dialysate (35.5-36 °C), sodium profiling (145 mEq/L to 140 mEq/L), UF profiling (higher first, lower later), avoid excessive UF rates (keep < 500 mL/hours). Treatment: Trendelenburg position, reduce or stop UF temporarily 100-250 mL saline bolus, consider midodrine or vasopressor support if recurrent
Transition strategy	From CRRT to SLED: Start with 10-12 hours daily sessions, assess tolerance for 2-3 sessions, if stable, continue until recovery or transition to conventional HD from SLED to conventional IHD: Gradually reduce session length: 10 hours → 8 hours → 6 hours → 4 hours. Gradually increase dialysate flow: 200 mL/minute → 300 mL/minute → 400 mL/minute → 500 mL/minute. Transition when hemodynamically stable for 48 hours. Consider alternate day schedule (Monday-Wednesday-Friday). Criteria for transition: Hemodynamic stability (no vasopressors), improving urine output, stable electrolytes and acid-base
Relative contraindications	Severe hemodynamic instability requiring continuous vasopressor titration (consider CRRT). Intracranial hypertension with cerebral edema (prefer CRRT for slower changes). Multiple organ failure requiring multiple continuous therapies. Massive fluid overload requiring urgent removal > 8 L in 24 hours (consider CRRT or IHD)
Special populations	Elderly patients: Start conservatively: Dialysate flow 150 mL/minute, UF 200 mL/hour, monitor closely for hypotension. Post-cardiac surgery: Prefer nocturnal schedule, consider minimal/no anticoagulation, watch for bleeding. Septic shock: May need daily treatment even if marginally stable, higher clearance beneficial for cytokine removal, monitor lactate trends

SLED: Sustained low-efficiency dialysis; CRRT: Continuous renal replacement therapy; HD: Hemodialysis; BUN: Blood urea nitrogen; CBC: Complete blood count; UF: Ultrafiltration; IHD: Intermittent hemodialysis.