Managing Phosphate Repletion During Continuous Renal Replacement Therapy in the Setting of Severe Hyperbilirubinemia
- Hemodialysis: Case Reports, Series, QI Projects
November 04, 2023 | Location: Exhibit Hall, Pennsylvania Convention Center
Abstract Time: 10:00 AM - 12:00 PM
- 801 Dialysis: Hemodialysis and Frequent Dialysis
- Jones, Jason Andrew, Walter Reed National Military Medical Center, Bethesda, Maryland, United States
- Im, Ellen E., Walter Reed National Military Medical Center, Bethesda, Maryland, United States
- Y'Barbo, Brian C., Walter Reed National Military Medical Center, Bethesda, Maryland, United States
Continuous renal replacement therapy (CRRT) is commonly used for critically ill patients with acute kidney injury. Among CRRT-associated adverse effects, hypophosphatemia is common. Strategies to prevent or treat hypophosphatemia include protocolized phosphate replacement and use of dialysate/replacement solutions containing phosphate. Most patients on CRRT require phosphate supplementation, particularly after the first 48 hours. Our facility, which uses dialysate without phosphate, has a replacement protocol guided by serum phosphate levels drawn every 6 hours.
A patient with acute-on-chronic alcoholic liver disease and hepatorenal syndrome was treated with continuous veno-venous hemodialysis without replacement fluid: Blood flow rate 300 ml/min and dialysate flow rate 29 ml/kg/hr. The patient had severe jaundice with total bilirubin of 35 mg/dL. This rendered the colorimetric assay of serum phosphorus inaccurate and not reportable. Protocolized phosphate replacement based on serum levels became impossible.
To measure serum phosphate without bilirubin interference, we measured phosphate levels in the effluent as a surrogate. Simultaneously, we measured serum urea nitrogen (SUN) and effluent dialysate urea nitrogen (EDUN), as a quality control measure to assess dialysate saturation.
During CRRT, 90-100% dialysate saturation is assumed to occur for small molecules with sieving coefficients near 1.0, such as urea and phosphate. EDUN (56mg/dL) agreed closely with SUN (52.4mg/dL), demonstrating that effluent dialysate was saturated and in equilibrium with plasma. Dialysate phosphate was 4.6mg/dL. We inferred that dialysate phosphate was reasonably equivalent to serum phosphate and were able to circumvent bilirubin interference with serum phosphate assay. The patient received protocol-driven phosphate replacement, guided by dialysate effluent phosphorous measurements, which ranged between 2.4-5.1mg/dL. The use of effluent phosphorus levels as a serum phosphorus surrogate provides a novel approach for guiding phosphate replacement in patients with severe hyperbilirubinemia.
The views expressed in this abstract are those of the author(s) and do not necessarily reflect the official policy of the Department of Defense or the U.S. Government.