Sustained Low-Efficiency Dialysis (SLED) Therapy is a specialized dialysis technique widely used in the management of acute kidney injury (AKI) and critical illnesses in intensive care units (ICUs). It represents a hybrid approach that combines the benefits of conventional intermittent hemodialysis (IHD) and continuous renal replacement therapy (CRRT).
SLED provides a gentler and more hemodynamically stable treatment for patients who are critically ill, especially those with low blood pressure or multi-organ dysfunction. Understanding this therapy is essential because it has become a preferred renal replacement modality in many hospitals worldwide.
The kidneys play a vital role in filtering blood, removing waste products, regulating electrolytes, balancing fluids, and maintaining acid-base stability. When the kidneys fail acutely, toxins and excess fluids accumulate rapidly, causing life-threatening imbalances.
Traditional hemodialysis is often too harsh for unstable patients, while CRRT requires continuous monitoring, advanced resources, and high cost. SLED was developed as a middle ground—delivering effective solute clearance and fluid removal over an extended period with less strain on the heart and circulation.
SLED is usually performed for 6–12 hours daily using standard dialysis machines but with modified settings such as lower blood flow and dialysate flow rates.
SLED therapy is not a disease itself but a treatment for conditions that cause acute kidney dysfunction. Common causes requiring SLED include:
Sepsis and septic shock – the most frequent trigger of AKI in ICU patients.
Severe dehydration or shock – leading to reduced kidney perfusion.
Drug toxicity – nephrotoxic medications or poisoning with dialyzable substances.
Rhabdomyolysis – breakdown of muscle tissue releasing toxins harmful to kidneys.
Major surgery or trauma – especially cardiac surgery or burns.
Multi-organ failure – where kidney dysfunction develops alongside heart, liver, or lung issues.
Patients requiring SLED often present with features of acute kidney failure, such as:
Reduced urine output (oliguria or anuria).
Fluid overload leading to swelling, pulmonary edema, or breathing difficulties.
Electrolyte imbalances (e.g., high potassium levels causing arrhythmias).
Uremic symptoms such as confusion, nausea, vomiting, and seizures.
Metabolic acidosis causing rapid breathing and fatigue.
Low blood pressure, often associated with septic or cardiogenic shock.
Before initiating SLED, doctors confirm kidney dysfunction through clinical evaluation and laboratory tests. Diagnostic steps include:
Clinical examination – assessing fluid balance, vital signs, and consciousness level.
Blood tests – elevated serum creatinine, blood urea nitrogen (BUN), and abnormal electrolytes.
Arterial blood gas (ABG) – to detect metabolic acidosis.
Urine output monitoring – persistent low urine output is a key indicator.
Imaging – ultrasound to rule out obstructive causes of AKI.
The decision to initiate SLED is usually based on a combination of lab results, clinical instability, and the inability to tolerate conventional hemodialysis.
Treatment of acute kidney injury depends on the cause and severity:
Conservative / Non-dialytic management
Fluid resuscitation or restriction as needed.
Correction of electrolyte imbalances with medications.
Discontinuation of nephrotoxic drugs.
Treating underlying conditions such as infection or shock.
Renal replacement therapies
Intermittent Hemodialysis (IHD): Short sessions (3–4 hours) but often poorly tolerated in unstable patients.
Continuous Renal Replacement Therapy (CRRT): Provides continuous, gentle clearance but is resource-intensive.
SLED: A compromise between IHD and CRRT, offering prolonged but intermittent therapy with greater hemodynamic stability.
SLED is performed using standard dialysis machines with modified parameters. Typical steps include:
Vascular Access – usually via a central venous catheter inserted into a large vein (e.g., internal jugular or femoral vein).
Machine Setup – blood flow rates are reduced (100–200 mL/min), and dialysate flow is kept low (100–300 mL/min).
Duration – the session lasts 6–12 hours, longer than conventional dialysis but shorter than CRRT.
Monitoring – vital signs, fluid balance, electrolytes, and acid-base status are checked frequently.
Anticoagulation – may be used to prevent clotting of the dialysis circuit, depending on patient condition.
This extended, slower clearance ensures effective removal of toxins and fluid while reducing the risk of sudden drops in blood pressure.
After SLED therapy, patients require careful monitoring and supportive care:
Vital signs and hemodynamics – to ensure stability after fluid removal.
Electrolyte checks – particularly potassium, sodium, and calcium.
Nutritional support – tailored diets with adequate calories, protein, and fluid control.
Fluid management – balancing intake and output to avoid overload.
Monitoring for kidney recovery – serial creatinine and urine output assessments.
Some patients may need repeated SLED sessions until kidney function recovers or a long-term dialysis plan is established.
Although safer than conventional hemodialysis for critically ill patients, SLED is not free from risks:
Low blood pressure (hypotension), though less common than with IHD.
Electrolyte disturbances if not carefully monitored.
Clotting or infection of the vascular access catheter.
Bleeding risks if anticoagulants are used.
Fatigue and weakness after prolonged sessions.
The outcome of patients on SLED depends largely on the underlying illness rather than the dialysis itself. In sepsis-related AKI, mortality remains high despite therapy. However, SLED often provides a critical bridge, allowing time for organ recovery while maintaining fluid and metabolic balance.
For patients with reversible causes of kidney injury, prognosis is good, and many regain adequate kidney function after supportive therapy.
Patients or caregivers should seek urgent medical attention if any of the following occur:
Sudden drop in urine output.
Swelling, breathlessness, or unexplained weight gain (fluid overload).
Confusion, seizures, or persistent nausea.
Very high blood pressure or sudden low blood pressure.
Signs of infection at dialysis catheter site (redness, pain, discharge, fever).
Early evaluation can prevent progression to life-threatening complications.
SLED Therapy is an important advancement in renal replacement therapy, especially suited for critically ill patients who cannot tolerate conventional dialysis. By offering gentle yet effective clearance of toxins and fluids, it provides a vital bridge during acute illness.
While it is not without risks, SLED has proven to be a practical, cost-effective, and life-saving option in intensive care settings. Patients and families should understand that the choice of dialysis method depends on individual health status, and consultation with healthcare professionals is essential for the best outcomes.
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