366	S. Prakash and A. Majumdar

•Treatments are deliberately intermittent rather than attempting to be continuous, with session longer in duration than conventional hemodialysis (HD).

•Solute and fluid removal is slower than conventional HD, but faster than CRRT. This allows for down timing of dialysis duration compared to CRRT without compromise in dialysis dose.

•They are easy to perform with modification of the standard dialysis machine, allow flexibility for procedure and diagnostic tests, allow a break in anticoagulation exposure, and are less staff intensive.

•SLED and other hybrid therapies such as SLED-F have a lot of potential to be of use when CRRT is not available.

3.Intermittent hemodialysis

•This is the conventional hemodialysis modality.

4.Slow continuous ultrafiltration (SCUF)

•This modality does not require dialysate or any replacement fluids.

•Here, therapeutic goal is to safely remove large volumes of fluid by hydrostatic pressure, with no intent to substantially remove solute.

•Ultrafiltration (UF) can be adjusted to cause dramatic fluid shifts; however, average UF rate ranges up to 2 L/h.

•As SCUF is a longer duration therapy, blood flow rates are less than intermittent HD, about 100–180 mL/min.

•SCUF is primarily used when the fluid removal goals are gradual and modest.

5.Peritoneal dialysis

•This modality of RRT utilizes the peritoneum as the dialyzer membrane.

•The dialysate fluid is instilled periodically in the peritoneum and drained out to achieve solute removal across a diffusion gradient.

•Fluid removal is achieved by osmosis by changing the glucose content of the dialysate fluid as necessary.

•This modality is effective when the patient is not too catabolic or hypotensive, or on vasopressor support.

•It is advantageous as it is gentle and continuous and it does not need anticoagulation, suitable for patients who have had a bleed, especially intracranial.

•Due to infection risk, this is not practiced commonly.

Suggested Reading

1.Casey ET, Gupta BP, Erwin PJ, Montori VM, Murad MH. The dose of continuous renal replacement therapy for acute renal failure: a systematic review and meta-analysis. Ren Fail. 2010; 32(5):555–61.

Systematic review on the subject. Increased dosing of CRRT was not associated with a decrease in mortality of patients with ARF in an intensive care unit setting.

2.Fieghen H, Wald R, Jaber BL. Renal replacement therapy for acute kidney injury. Nephron Clin Pract. 2009;112(4):c222–9.

Recent trials indicate that continuous renal replacement therapy does not confer a survival advantage as compared to intermittent hemodialysis. Furthermore, there is no evidence to

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support a more intensive strategy of renal replacement therapy in the setting of AKI. There is comparatively limited data regarding the ideal timing of renal replacement therapy initiation and the preferred mode of solute clearance.

3.Bagshaw SM, Berthiaume LR, Delaney A, Bellomo R. Continuous versus intermittent renal replacement therapy for critically ill patients with acute kidney injury: a meta-analysis. Crit Care Med. 2008;36(2):610617.

Numerous issues related to study design, conduct, and quality that dispute the validity and question any inferences can be drawn from these trials. In the context of these limitations, the initial RRT modality did not seem to affect mortality or recovery to RRT independence. There is urgent need for additional high-quality and suitably powered trials to adequately address this issue.

4.Davenport A. Renal replacement therapy in acute kidney injury: which method to use in the intensive care unit? Saudi J Kidney Dis Transpl. 2008;19(4):529–36.

Comprehensive review on the subject. The choice of RRT modality should be guided by the individual patients’ clinical status, the medical and nursing expertise in the local intensive care unit, and the availability of RRT modality.

5.5. Ronco C, Bellomo R, Homel P, Brendolan A, Dan M, Piccinni P, La Greca G. Effects of different doses in continuous veno-venous haemofiltration on outcomes of acute renal failure: a prospective randomised trial. Lancet. 2000;356(9223):26–30.

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