Body surface area limitations in achieving adequate therapy in peritoneal dialysis patients.

OBJECTIVE

To estimate the maximal body surface area (BSA) at which anuric chronic peritoneal dialysis patients can achieve adequate peritoneal dialysis using a variety of continuous ambulatory peritoneal dialysis (CAPD) and cycler regimens. Adequate dialysis was defined as a creatinine clearance of either 60 L/week/1.73 m2 or 70 L/ week/1.73 m2.

DESIGN

Calculation of daily peritoneal creatinine clearances using standard formulas. For CAPD patients, creatinine clearance was calculated using published values for dialysate-to-plasma ratios for creatinine (D/P cr) measured over a 24-hour period and assuming a daily ultrafiltration rate of 1.5 to 2.0 L/day. For cycler patients, creatinine clearance was calculated for both one- and two-hour dwell volumes, using published values for D/P cr from the peritoneal equilibration test and assuming a daily ultrafiltration rate of 2.0 L/day. All clearances were corrected to a normalized body surface area of 1.73 m2.

RESULTS

For CAPD patients, 2-L dwell volumes can provide a weekly creatinine clearance of 60 L/week/1.73 m2 in patients with BSA < 1.45 m2 in the high transporter group and with BSA < 1.2 m2 in the low-average transporter group. Increasing dwell volume from 2.0 to 2.5 L increases these BSA limits in the four transport groups by 0.2-0.3 m2. Cycler therapy is not a viable option for patients in the low transporter group, and this therapy can achieve adequate creatinine clearances in patients in the low-average transport group only with large dwell volumes and in patients with BSA < 1.55 m2. However, in the high-average and high transporter groups, cycler therapy provides for superior creatinine clearances compared to CAPD patients using similar dwell volumes.

CONCLUSIONS

Adequate creatinine clearances in anuric patients are most likely to be achieved in patients with BSA > 2.0 m2 if they have high-average or high transport characteristics and are receiving cycler therapy with large dwell volumes and at least one daytime dwell. However, adequate creatinine clearances may be difficult to achieve in anuric patients who have a large BSA and a low or low-average transport type, regardless of peritoneal dialysis modality. These patients should be considered for either high-dose peritoneal dialysis (multiple daytime and nighttime exchanges) or hemodialysis therapy.