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To achieve the desired clearance levels, individually tailored PD prescriptions are essential. Body surface area (BSA), residual renal function, and peritoneal membrane transport characteristics are fundamental to the PD prescription. In order to confirm that it is possible to achieve the recommended clearance levels with reasonable PD prescriptions, we examined data from 806 randomly selected adult male and female PD patients from 39 U.S. centers. All 806 patients underwent a standard four-hour 2-L 2.5% dextrose peritoneal equilibration test (PET).

BODY SURFACE AREA

Body surface area obviously affects the amount of dialysis a patient needs. While 1.73 m² is considered the average adult BSA, in these 806 patients (8) the median body surface area was 1.85 m² (Table 2). In fact, 75% of the patients in this study had BSA > 1.71 m², reinforcing the need to individualize PD prescription and utilize larger volumes of solution.

RESIDUAL RENAL FUNCTION

Residual renal function makes it easier to achieve clearance guidelines. For example, 1 mL/min of glomerular filtration rate (GFR), calculated as the sum of the urea and creatinine clearances divided by 2 (corrected Ccr), adds 10 L/wk of Ccr. Similarly, for each 1 mL/min of urea clearance, 0.25 is added to the total weekly KT/V for a 70-kg person.

The peritoneal dialysis prescription must be adjusted as RRF declines. It is recommended that one replace overall solute clearance loss due to a decrease in RRF with a similar increase in peritoneal clearance. RRF must be measured every three months or presumed to be absent in determining the PD prescription. However, because the decline in RRF is unpredictable and may occur at different rates for different disease states, specific circumstances (e.g., antibiotic usage) may merit more frequent monitoring.

PERITONEAL MEMBRANE TRANSPORT CHARACTERISTICS

Peritoneal membrane transport has a significant impact on dialysis clearance and, therefore, the PD prescription. Membrane transport characteristics in the same group of 806 patients were assessed using the standard PET (9). A different distribution of peritoneal transport characteristics from that originally described by Twardowski was found in this group of patients (Figure 3), possibly because of the much higher number of patients in the current study. A small fraction (5.6%) fell into the low transport group, which is the hardest to treat with PD. Patients with high solute transport membranes comprised 10.4% of the population. Note in Table 3 that peritoneal transport characteristics were randomly distributed within each BSA group.

Peritoneal Dialysis International, Vol. 16, pp. 448­456 Printed in Canada. All rights reserved. Copyright © 1996 International Society for Peritoneal Dialysis 0896-8608/96 $3.00 + .00