Abstract
Urea kinetic modeling (UKM) is an established method for quantitating hemodialysis, with target values clearly defined. Precise methods for measuring continuous ambulatory peritoneal dialysis (CAPD) prescriptions are less well-defined, and 24-hour collections of dialysate effluent are logistically impractical.
UKM parameters derived from an abbreviated (4-hour) collection period were compared with simultaneously obtained 24hour collections of urine and dialysate effluent in 22 CAPD patients. Daily Kt/V was calculated from total (residual renal and peritoneal) urea clearance and an anthropometric-derived total body water volume. Results yielded from the 24-hour collection included a mean Kt/V of 0.29±0.09, and mean protein catabolic rate (PCR) of 0.84±0.24 g/kg/day. Daily Kt/V values were calculated from each individual dialysate cycle. The first morning cycle after an overnight dwell correlated best with results obtained using 24-hour collections (r=0.921; p<0.0001) with no significant differences in Kt/V found (p=0.454) between the short and 24-hour methods. Daily Kt/V values converted by exponential transformation to a thrice-weekly hemodialysis value yielded a Kt/V equivalent of 1.02±0.40.
UKM using an abbreviated collection period is an accurate and practical tool for quantitating CAPD adequacy in a routine clinical setting.
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