Introduction
Sustained low-efficiency dialysis (SLED) is a therapy for renal replacement for individuals with end-stage kidney disease in the intensive care unit. The hybrid treatment has features of both conventional intermittent hemodialysis (IHD) and continuous renal replacement therapy (CRRT). As it has certain inherent advantages, it plays a vital role for critically ill patients. SLED is administered via conventional hemodialysis technology over a prolonged period, usually eight to twelve hours, and more frequently than traditional intermittent hemodialysis. This will allow for the gradual removal of fluid with less hemodynamic perturbation.
SLED is often used for individuals with acute kidney injury(AKI). AKI is characterized by a sudden decrease in kidney function, which is characterized by dysregulation of fluid, electrolytes, and acid-base homeostasis. Signs and symptoms of severe cases of acute kidney injury include edema of the extremities, decreased urinary output, fatigue/tiredness, dyspnea, nausea, confusion, chest pain or chest pressure, seizures, or coma.
When Is Sustained Low Efficiency Dialysis Indicated (SLED)?
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SLED is feasible for critically ill patients with acute kidney injuries, including those with renal failure.
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Compared to continuous renal replacement therapies, SLED provides equivalent hemodynamic control and solute removal, a reduced need for blood transfusions, and lower intensive care costs.
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This dialysis appears appropriate in the critical care setting when conventional intermittent hemodialysis has failed or is withheld.
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It is also used to treat hemodynamically unstable, critically ill pediatric patients with severe acute kidney injuries.
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SLED can be administered routinely without the need for anticoagulation therapy.
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SLED in continuous mode (C-SLED) is given for patients with oliguria, hypotensive, and require large amounts of fluids.
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Compared to traditional SLED treatments, C-SLED patients will receive dialysis for a longer period.
What Are the Considerations of SLED in the Patient and Special Population?
In critically ill patients undergoing SLED, the robust blood solute clearance that occurs during the SLED raises concerns about suboptimal drug concentrations. To ensure adequate delivery of antibiotic therapy in this setting, careful dosing and calculation of dosing intervals are essential. SLED might minimize urea disequilibrium in critically ill patients, reducing the occurrence or severity of dialysis disequilibrium syndrome. Over a relatively short time, dialysis disequilibrium syndrome is triggered by a rapid reduction in solute levels. Initially, patients with this syndrome might present with nausea, vomiting, headaches, fatigue, and restlessness, progressing to mental status changes, coma, and generalized seizures.
What Is SLED Technique?
SLED is a renal replacement therapy that is intermittent for an extended period with lower solute clearances and lower ultrafiltration rates compared with conventional intermittent hemodialysis. It is a hybrid technique that aims to combine the hemodynamic stability of CRRT with the efficiency of IHD. Hemodialysis is the classic modality used, which is named SLED. Prescription can also be performed with hemofiltration or hemodiafiltration, which combines diffuse and convecting clearances, known as SLED-F.
What Are the Advantages of SLED?
The following are the advantages of SLED:
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The exposure of patients to anticoagulants is less as the sessions are shorter.
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Efficient clearance of small solutes.
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It has good hemodynamic tolerability and is much better compared to conventional intermittent hemodialysis.
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The treatment schedules are flexible. The short duration of the therapy leaves the patient free most of the day.
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It is a lot cheaper than other therapies.
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Easy to perform.
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Anticoagulant therapy might not be required, as saline flushes are usually sufficient.
How Is SLED Monitored?
In the intensive care unit, dialysis is a labor-intensive process where up to seven percent of the individuals are treated with some form of renal replacement therapy. SLED's prolonged nature necessitates implementing a telemetry system that maximizes intervention response time. When using SLED in an intensive care unit, researchers have evaluated a remote alert alarm system that will wirelessly notify hemodialysis technicians of specific machine alarms. It is necessary to carefully monitor the patients undergoing SLED for coagulation issues, particularly extracorporeal circuit clotting. However, using regional citrate anticoagulation protocols may help reduce these adverse events.
It is essential to carefully monitor patients for hypophosphatemia which might require phosphate supplementation. The risk of hypophosphatemia during SLED can be significantly reduced by the use of sodium phosphate or a combination of a low-citrate solution with a phosphate-containing solution. SLED is commonly used to treat individuals with acute kidney infection, and these individuals often present with cardiac comorbidities such as myocardial infarction, heart failure, stroke, arrhythmia, cardiac arrest, pericarditis and endocarditis, and also complications related to electrolyte imbalances and metabolic acidosis that often require close monitoring and treatment.
What Are the Complications of SLED?
There are both technical and clinical complications in SLED, including vascular access malfunctions, hematomas, pneumothorax/hemothorax, catheter kinking, circuit clotting, line-catheter disconnection, and air embolism. Clinical complications include coagulation disturbances, infection and sepsis, allergic reactions, cardiovascular and hemodynamic instability, electrolyte abnormalities, and nutrient losses.
The relatively common complications associated with SLED are:
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Hypotension - Hypotension can occur although ultrafiltration in SLED is generally well tolerated. Sometimes, temporary increase of inotropes can occur.
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Hypophosphatemia - Electrolyte abnormalities are more frequent with longer treatments, especially when high-flux dialyzers are used. The most common abnormality is hypophosphatemia, which leads to the need for phosphate replacement. Hypophosphatemia can sometimes result in respiratory muscle weakness, increase the risk of arrhythmia, and often be associated with longer ICU and hospital stays.
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Amino Acid Losses - Amino acid loss is one of the significant complications of SLED. On treatment days, protein supplementation of more than 0.2 g/kg/day should be administered.
What Is the Drug Dosage in SLED?
In terms of rates of drug removal, there are considerable differences between SLED, IHD, and CRRT. Due to the high heterogenicity of treatment prescriptions, drug dosing in SLED is difficult. Therefore, there is a substantial risk of underdosing essential drugs like antibiotics.
Conclusion
SLED is a common technique that combines the advantages of conventional intermittent hemodialysis (IHD) and continuous renal replacement therapy (CRRT). It is the first choice of treatment in mild hemodynamically unstable patients or as a bridge between CRRT and IHD. The selection of the best treatment should be individualized for patient characteristics, center experience, and the ICU's logistical capacity.
