Safety of regional citrate anticoagulation for continuous sustained low efficiency dialysis (C-SLED) in critically ill patients

Background. Sustained low efficiency dialysis (SLED) is a hybrid therapy that uses a conventional hemodialysis machine to deliver lower solute clearance over prolonged periods of time, typically 8 to 12 hours per treatment, and utilizes the same sodium and bicarbonate concentrations as intermittent hemodialysis. The therapy has been shown to be an effective dialysis mode for the critically ill patient with acute renal failure and hemodynamic instability. At our institution, critically ill patients requiring renal replacement therapy receive SLED on a continuous, 24-hour schedule (C-SLED). The higher dialysis dose with C-SLED compared to continuous venovenous hemodiafiltration (CVVHDF) or traditional SLED would likely alter the prescription needed to provide regional citrate anticoagulation and the incidence of hypematremia and metabolic alkalosis. Objective. To evaluate the safety of utilizing regional citrate anticoagulation with continuous SLED in critically ill patients who frequently clot the hemofilter and have contraindications to systemic anticoagulation with heparin. We hypothesized that the higher dialysis dose with C-SLED would affect the prescription of citrate anticoagulation and the development of hypernatremia and metabolic alkalosis. Design. We prospectively followed the first 20 patients who received regional citrate anticoagulation on C-SLED for acute renal failure in the intensive care unit. Important outcomes measured included serum sodium, bicarbonate, ionized calcium concentration, serum pH, and PCO2. The number of clotting episodes for each patient while on regional citrate anticoagulation was recorded. Setting. Surgical and medical intensive care units at The University of Texas MD Anderson Cancer Center. Results. In over 2200 hours of continuous dialysis with citrate anticoagulation none of the 20 patients had derangements in the serum sodium or acid base status requiring cessation of regional citrate anticoagulation. In 14 patients, no clotting occurred during 1500 hours of SLED with the citrate infusion. There were eight episodes of hemofilter clotting in six patients during 750 hours of C-SLED. Conclusion. Regional citrate anticoagulation is a safe method of anticoagulation in critically ill patients on continuous SLED.