Residual volume in continuous ambulatory peritoneal dialysis patients from various solute calculations.

Residual volume (RV) has been measured using various methods and various solutes. This prospective study set out to determine residual volume by using various solute calculations, and to estimate mean residual volume in stable Thai CAPD patients. Complete data from 9 patients (6 males, 3 females) were analyzed. Residual volume was calculated using various solutes including sodium (Na), potassium (P), glucose (G), urea (U), and creatinine (C). The calculation using sodium was too variable to use to calculate a mean. Mean of residual volume was calculated from the other solutes as RV1 (mean of PUC), RV2 (mean of GUC), and RV3 (mean of PGUC). Mean residual volumes did not correlate with sex, body weight, body surface area, hematocrit, albumin, or membrane characteristics (drained volume). Comparing all means calculated in our study, creatinine was the solute that yielded the most accurate mean, with a correlation coefficient of 0.877, 0.965, and 0.956 for RV1, RV2, and RV3 respectively. In this study, mean residual volumes were 212.49 +/- 100.03 mL, 255.23 +/- 142.58 mL, and 250.42 +/- 121.60 mL for RV1, RV2, and RV3 respectively.