Sustained Low-Efficiency Dialysis

SLED stands for Sustained Low-Efficiency Dialysis.

It is a form of dialysis that combines aspects of both intermittent hemodialysis (IHD) and continuous renal replacement therapy (CRRT), offering a more gentle and gradual approach to dialysis. It is primarily used in critically ill patients with acute kidney injury (AKI) or those requiring dialysis but who may not tolerate more aggressive methods.

Key Features of SLED:

Dialysis Technique:

SLED is a form of intermittent hemodialysis, but with lower intensity and longer duration compared to conventional hemodialysis.
The therapy is typically done over 6 to 12 hours, which is much longer than conventional hemodialysis (which is usually 3 to 4 hours), but shorter than the continuous therapy used in CRRT.
SLED uses a lower blood flow rate (typically between 150-250 mL/min), which makes it gentler and less likely to cause fluctuations in the patient’s blood pressure or hemodynamics.

Purpose:

SLED is mainly used to treat acute kidney injury (AKI), where the kidneys are temporarily unable to filter waste products and regulate fluid balance.
It is often preferred in critically ill patients who are hemodynamically unstable and may not tolerate the rapid fluid and solute shifts seen in traditional intermittent hemodialysis or the high fluid removal rates in CRRT.

Dialysis Efficiency:

SLED is less efficient in removing waste products and electrolytes than full-scale intermittent hemodialysis. However, its slower and more gradual fluid removal helps reduce the risk of complications, especially in patients with unstable blood pressure or those who are prone to hypotension.
Unlike CRRT, which is continuous, SLED allows for intermittent sessions and can be managed more easily by the healthcare team with less resource usage.

Advantages of SLED:

Hemodynamic Stability:

The slower, more gradual nature of fluid and solute removal with SLED makes it well-tolerated by critically ill patients, especially those with unstable blood pressure.

Longer Duration:

With treatments lasting several hours, SLED allows for a more controlled fluid removal, avoiding the rapid changes associated with traditional hemodialysis.

Improved Tolerance:

Patients who cannot tolerate traditional hemodialysis or CRRT due to the rapid shifts in fluids, electrolytes, or pressure can benefit from SLED, as it reduces the risk of complications such as hypotension, arrhythmias, or severe fluid imbalances.

Less Intensive than CRRT:

SLED requires fewer resources and is generally more feasible for hospitals that may not have access to the infrastructure required for continuous renal replacement therapy (CRRT).

Indications for SLED:

Acute Kidney Injury (AKI)

It particularly in patients who are hemodynamically unstable or have fluid overload but do not need the intensity of traditional intermittent hemodialysis.
Fluid Overload:

SLED is useful in situations where fluid removal is necessary, such as in cases of heart failure, liver failure, or sepsis.
Intensive Care Unit (ICU) Settings:

It is most commonly used in critically ill patients in the ICU who have AKI and are unable to tolerate more aggressive forms of dialysis.

Risks and Limitations:

Clotting:

As with other forms of dialysis, there is a risk of clotting in the dialysis circuit, which may reduce the efficiency of the treatment.

Electrolyte Imbalance:

Although the slower nature of SLED reduces the likelihood of sudden electrolyte shifts, careful monitoring is still needed to prevent issues such as hyperkalemia or hyponatremia.

Limited Waste Removal:

SLED is not as efficient in removing waste products compared to conventional hemodialysis, which may be a limitation if rapid removal of toxins is needed.

Availability:

SLED requires specialized equipment and expertise, which may not be available in all healthcare settings.

Conclusion:

SLED is a useful dialysis modality for critically ill patients, particularly those with acute kidney injury, who require dialysis but are at risk of complications due to hemodynamic instability. By offering a middle ground between the intensity of traditional hemodialysis and the continuous nature of CRRT, SLED provides a gentler, more controlled approach to managing fluid and waste removal in these patients.