Ultrafiltration Failure

Peritoneal Dialysismedium

A 38-year-old man with ESKD from type 1 diabetes has been on peritoneal dialysis for 4 years and, apart from two early peritonitis episodes, has done well. He is on automated PD with five short overnight dwells (2.5% dextrose) and a long daytime dwell (1.5% dextrose). His home records show declining ultrafiltration, especially on the daytime drain, and his weight has risen from 190 to 207 lb with a blood pressure of 174/96 mmHg and 2+ peripheral edema; lungs are clear, the abdomen is soft with no hernia, and the catheter exit site is clean. A repeat peritoneal equilibration test shows the 4-hour dialysate-to-plasma creatinine ratio has risen from 0.75 to 0.90. Which of the following is the MOST appropriate management?

  1. A.Change the daytime dwell to 4.25% dextrose
  2. B.Switch the daytime dwell to icodextrinCorrect
  3. C.Discontinue the daytime long dwell
  4. D.Increase the duration of cycler time

Explanation

The rising 4-hour D/P creatinine indicates fast peritoneal solute transport. With long glucose dwells, glucose is absorbed relatively rapidly and the crystalloid osmotic gradient dissipates, causing poor ultrafiltration. Icodextrin is a high-molecular-weight glucose polymer that generates sustained colloid osmotic pressure during a long dwell and is absorbed much more slowly than dextrose (predominantly via lymphatic pathways). It is therefore preferred for the long dwell in fast transporters with inadequate ultrafiltration. Simply increasing long-dwell dextrose increases glucose exposure and may still lose the gradient quickly.

Why each option

A.
4.25% dextrose in a long dwell is rapidly absorbed in a high transporter, giving only transient ultrafiltration with a higher glucose/metabolic load.
B.
Correct. Icodextrin sustains ultrafiltration across the long dwell in high transporters via colloid osmosis.
C.
Stopping the daytime dwell would reduce solute clearance and overall ultrafiltration.
D.
Adding cycler time does not correct ultrafiltration loss during the long daytime dwell.

Reference: ISPD recommendations for evaluation of peritoneal membrane dysfunction (Perit Dial Int. 2021); pharmacokinetic and randomized data on icodextrin for long dwells.

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