What factors can cause ultrafiltration failure in PD?

• A. Dehydration due to excessive fluid removal
• B. Low potassium causing cramps
• C. Deteriorating peritoneal membrane, high transport status with rapid fluid removal, or catheter-related problems; management includes prescription adjustments, icodextrin, and possibly transition to hemodialysis.
• D. Increased urine output alone fixes ultrafiltration

Answer: (C)

Ultrafiltration failure in PD happens when the peritoneal membrane loses its ability to remove water effectively, often due to changes in the membrane itself or problems with how the dialysis therapy is prescribed or delivered. Over time the membrane can become more of a high transporter, meaning solutes and water cross quickly. In high transport membranes, the osmotic gradient from the standard glucose-based solutions collapses faster during the dwell, so less water is drawn across and ultrafiltration falls short, especially with shorter dwell times. Catheter-related problems, such as flow issues or blockages, can further reduce the ability to exchange fluid, worsening ultrafiltration. The way to manage this is to adjust the PD prescription (for example, longer dwell times or different osmotic agents), use icodextrin for longer dwells to maintain a stronger osmotic gradient, and, if needed, consider switching to hemodialysis when the peritoneal membrane no longer provides adequate UF.

Other options don’t fit because dehydration can reduce overall fluid status but isn’t the mechanism of ultrafiltration failure; cramps from low potassium aren’t about UF capacity; and increased urine output alone does not resolve ultrafiltration failure.