**8. Single-pass albumin dialysis (SPAD)**

This purification system that uses the physical foundation of diffusion with a dialysis bath enriched with albumin in 3–4% concentrations that act as a binder for substances bound to proteins. This technique uses a continuous renal replacement therapy (CRRT) machine in continuous venovenous hemodialysis modality, with a dialysate flow of 700–1000 ml/min. The dialysate flow with albumin will allow the capture of lipophilic molecules present in the patient's blood that will bind to the albumin that circulates in the countercurrent direction to the blood flow through the filter, allowing the elimination of bilirubin, bile acids, and nitrogen acids (**Figure 7**).

#### **Figure 7.**

*Single-pass albumin dialysis (SPAD). A) The technique uses a continuous renal replacement therapy (CRRT) machine in continuous venovenous hemodialysis modality, with a dialysate flow of 700–1000 ml/min, the dialysate is enriched with 3–4% albumin.*

This technique does not use additional cartridges or other extracorporeal circulation machines and can be performed in low-income countries.

There is evidence that SPAD allows a significant decrease in bilirubin similar to MARS, but it failed to lower bile acid and cytokine values [40], considering that the modality used is continuous venovenous hemodialysis and due to the screening coefficient of conventional membranes does not allow clearance of cytokines [41].

In a randomized crossover trial [42], of 34 patients with ACLF, who underwent dialysis with albumin, assigning the first session randomly to MARS or SPAD modality, the second session was assigned to a different therapy. Both therapies achieve a significant decrease in bilirubin, bile acids, and a greater decrease in creatinine with MARS. The significant decrease in fibrinogen in SPAD was identified as an adverse effect, and both therapies decreased hemoglobin, hematocrit, and platelets. Both therapies are considered comparable, with the advantage of the lower costs of SPAD.
