Clinical Recommendations

• A systematic and thorough evaluation of fluid management should be considered a cornerstone of dialytic therapy. The routine monitoring and evaluation of volume status should be considered a necessary component of dialysis prescription and dialysis adequacy. Assessment, achievement, and maintenance of the target weight, with the aim of maintaining normotension with euvolemia, are essential. Regular assessment (annually, but more frequently if clinically indicated) of peritoneal function [peritoneal equilibration test (PET), modified], residual renal function, and solute clearance are essential.
• In the absence of validated readily applicable indicators of volume status, reliance on clinical judgment remains the physician's best guide.
• Adherence to sound physiologic principles in the design and implementation of PD prescriptions is essential to prevent the emergence of fluid overload. The most frequently ignored principles in PD, leading to ultrafiltration difficulties, are avoidance of long dwells in high transporters and maintenance of a balance between glucose concentration and dwell time. Prescription setting must consider these principles.
• In the evaluation of the causes of fluid overload, screening for reversible causes, such as dietary indiscretion and noncompliance, problems in prescription design, and mechanical problems, is imperative. These factors may account for a large proportion of the causes of fluid overload.
• Evaluation of peritoneal membrane-related causes of fluid overload requires adherence to a structured diagnostic framework. The first step involves evaluation of the ultrafiltration response to an effective osmotic challenge. The second step refines the diagnostic approach with an evaluation of the small solute transport profile.
• Evaluation of peritoneal membrane function in this context is best performed with a modified PET utilizing 4.25%/3.86% glucose. In effect, a net ultrafiltration greater than 400 mL/4 hours (a drain volume > 2400 mL/4 hours) effectively rules out any alterations in peritoneal functional parameters being responsible for inadequate fluid removal and the ensuing clinical syndrome.
• For patients with net ultrafiltration of less than 400 mL/4 hrs and a high transport profile of small solute clearance, automated PD and icodextrin for the long dwell are the recommended therapeutic approaches. This profile can also be seen during peritonitis, and several studies have indicated that ultrafiltration during an episode of peritonitis can be satisfactorily achieved with the use of icodextrin.
• Patients who are functionally anephric with net ultrafiltration of less than 400 mL/4 hrs and a low transport profile of small solute clearance, have both inadequate volume and inadequate solute removal; transfer to hemodialysis may be required for adequate patient management. Functionally anephric patients in this category often cannot be managed by PD. However, if some degree of residual renal function is present, maintenance on this dialytic modality may be feasible.
• Patients with a net ultrafiltration of less than 400 mL/4 hr and a low-average, average, or high-average transport profile, may have mechanical problems, high peritoneal absorption rate, or aquaporin deficiency. The diagnosis and management of each of these abnormalities is reviewed in the main text.