Amino acid losses during sustained low-efficiency dialysis in critically ill patients with acute kidney injury

Objective: Sustained low-efficiency dialysis (SLED) involves the use of standard dialysis machines for prolonged intermittent renal replacement therapy in critically ill patients. In this study we aimed to quantify dialysate amino acid (AA) and albumin losses in 5 patients who underwent successful SLED treatment. Design: This was a prospective observational study. Setting: The study was performed in a general intensive care unit. Subjects: The study was performed in critically ill patients with acute kidney injury undergoing SLED using low-flux hemodialyzers. Intervention: We performed total dialysate collection and measured dialysate AA profiles by reverse-phase high-pressure liquid chromatography using an automated AA analyser. Main outcome measure: Individual and total amino acid losses. Results: Albumin was undetectable in dialysate. The median (mean +/- SD) total amino acid loss was 15.7 (23.4 +/- 19.2) g/treatment, or 122.1 (180.6 +/- 148.5) mmol/treatment. Two patients were receiving intravenous nutrition. One patient had severe hepatic failure with encephalopathy, and had high dialysate AA levels with a total loss of 57 g/treatment. Conclusions: During SLED with low-flux hemodialyzers, albumin losses are negligible but AA losses to dialysate are comparable to those during continuous renal replacement therapy. Patients' nutritional protein prescriptions should be augmented to account for this.