Questions About PD
Volume overload in PD patients may have many causes, and therefore different solutions.
Paramount in any peritoneal dialysis patient who is volume overload is meticulous attention to salt and water intake. This is particularly important in patients with little or no residual renal function (RRF). Conventional management is to place patients on 2 g sodium restricted diet and consider fluid restriction as well, particularly if their RRF is poor. If patients do have RRF, loop diuretics should be employed. Note that with limited GFR, the dose of loop diuretics may need to be higher than used in the general population. Thiazides may be added as well.
Decreased oncotic pressure from a low albumin of any cause (liver disease, malnutrition, nephrotic syndrome), may also contribute to volume overload.
Systemic hyperglycemia may contribute by decreasing the glucose gradient between capillary and dialysate thus reducing osmotic movement of water.
Another issue is to consider is whether the prescription matches the membrane type. A high transporter will dissipate his or her glucose gradient rapidly leading to fluid retention during longer dwells due to loss of trans-capillary ultrafiltration and continued lymphatic absorption. Management for this may consist of shortening dwell times and/or adding an alternative osmotic agent such as icodextrin for any long dwells (i.e. overnight for CAPD or day dwell during APD).
One can also consider increasing the tonicity of glucose, but this is best used as a temporary strategy given the long term adverse effects of peritoneal glucose exposure.
Anything that interferes with draining of dialysis from the peritoneum may contribute to volume overload. Constipation for example may allow normal filling, but may interfere with draining and retained fluid will ultimately be absorbed. Leaks may also present with volume overload.
Ultrafiltration failure is another possibility of volume overload, but this would be unusual in a patient just starting PD. This can be suspected when volume overload persists despite optimization of all other factors, and can be confirmed with a PET test using a 2L, four hour dwell with 4.25% glucose. UF failure is defined by UF of < 400 ml.