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Kidney Week

Abstract: PO1202

Tailoring the Dialysis Prescription in Patients at Risk for Dialysis Disequilibrium Syndrome

Session Information

Category: Trainee Case Report

  • 701 Dialysis: Hemodialysis and Frequent Dialysis

Authors

  • Genena, Kareem, Baylor University Medical Center at Dallas, Dallas, Texas, United States
  • Ahmed, Shahbaz, Baylor University Medical Center at Dallas, Dallas, Texas, United States
  • Szerlip, Harold M., Baylor University Medical Center at Dallas, Dallas, Texas, United States
  • Schwartz, John C., Baylor University Medical Center at Dallas, Dallas, Texas, United States
Introduction

The dialysis disequilibrium syndrome (DDS) is a potentially fatal, preventable syndrome in uremic patients treated with dialysis. Urea kinetics can be used to tailor the dialysis prescription to a goal urea reduction ratio (URR) of less than 40%.

Case Description

A 22-year-old female patient presented to the emergency department with severe renal failure and a failing transplant secondary to noncompliance with medications for 1 year. Serum creatinine was 32 mg/dl, blood urea nitrogen (BUN) 226 mg/dl, potassium 9.2 meq/l and serum total carbon dioxide content 6 meq/l. Intermittent hemodialysis was started using a dialyzer with a mass transfer coefficient (koA) of 1200 ml/min, a blood flow rate of 250 ml/min, a dialysate flow rate of 500 ml/min and zero ultrafiltration. She was given 12.5 g of mannitol to reduce the risk of DDS. Her weight was 60 kg. After 1.5 hours of dialysis, the patient developed generalized seizures secondary to brain edema. BUN 6 hours after dialysis was 137 mg/dl. She was declared brain dead 4 days later.

Discussion

The dialysis disequilibrium syndrome results from osmotic shifts between the blood and the brain compartments. Rapid changes in BUN are known to contribute, but other osmotic substances may contribute to the development of DDS as well. Patients at risk for DDS include those with very elevated BUN, concomitant hypernatremia, metabolic acidosis, and those with low total body water volumes. There is no absolute cut off value for URR that is guaranteed to prevent DDS. However, a URR of 40-45% over 2 hours and a total decrease in serum osmolality no more than 24 mosm/kg per 24 hours are recommended.
A simplified relation between Kt/V and URR is provided by the equation: kt/V= -ln (1-URR). A URR of 40% is roughly equivalent to a kt/V of 0.5. Thus, targeting a kt/V of 0.5 is a reasonable goal for the initial treatment.
k can be plotted on the nomogram in figure 1 (used with permission) for a given dialyzer koA and blood flow rate. Using a 400 koA dialyzer at a blood flow rate of 200 ml/min for 120 minutes in a patient with a V of 30 l, the estimated kt/V is 0.45 and the estimated URR is <40%. When low-efficiency dialyzers are not available, other measures to lower clearance such as reversing dialysis lines or CRRT need to be considered. Sodium modeling and mannitol may also mitigate rapid changes in osmolality.