A quantitative description of solute and fluid transport during peritoneal dialysis

A quantitative description of solute and fluid transport during peritoneal dialysis. To investigate the relationship between dialysate glucose concentration and peritoneal fluid and solute transport parameters, 41 six-hour single dwell studies with standard glucose-based dialysis fluids containing 1.36% (N = 9), 2.27% (N = 9) and 3.86% (N = 23) anhydrous glucose were carried out in 33 clinically-stable continuous ambulatory peritoneal dialysis (CAPD) patients. Intraperitoneal dialysate volumes (VD) were determined from the dilution of mI-albumin with a correction applied for its elimination from the peritoneal cavity (KE,ml/min). Diffusive mass transport coefficients (KBD) were calculated from aqueous solute concentrations (with a correction applied for the plasma protein concentration and, for electrolytes, also for the Donnan factor) during a period of dialysate isovolemia. The intraperitoneal amount calculated to be transported by diffusion was subtracted from the measured total amount of solutes in the dialysate, yielding an estimate of non-diffusive solute transport. The intraperitoneal dialysate volume over time curve was characterized by: initial net ultrafiltration (lasting on average 92min, 160min and 197min and with maximum mean net ultrafiltration rates 6ml/min, 8ml/min and 14ml/min, respectively, for the 1.36%, 2.27% and 3.86% solutions); dialysate isovolemia (lasting about 120min for all three solutions) and fluid reabsorption (rate about 1ml/min for all three solutions). KBD for glucose, potassium, creatinine, urea and total protein did not differ between the three solutions and the fractional absorption of glucose was almost identical for the three glucose solutions, indicating that the diffusive transport properties of the peritoneum is not influenced by the initial concentration of glucose or the ultrafiltration flow rate. About 50% of the total absorption of glucose occurred during the first 90minutes of the dwell. The mean percentage of the initial amount of glucose which had been absorbed (%GA) at time t during the dwell could be described (r = 0.999) for all three solutions using the experimental formula %GA = 85 - 75.7 * e 0.005-*t After 360minutes, about 75% of the initial intraperitoneal glucose amount had been absorbed corresponding to a mean (± SD) energy supply of 75 ± 6kcal, 131 ± 18kcal and 211 ±26kcal for the three solutions. Non-diffusive (that is, mainly convective) transport was almost negligible for the less hypertonic solutions while it was estimated to account for 30 to 40% of the total peritoneal transport of urea, creatinine and potassium during the first 60minutes of the 3.86% exchange

Characterization of microcapsules

A review on the methods of characterization of multicomponent microcapsules. Requirements to measure the ingress and egress of small and macromols. through the membrane are discussed, along with the relevant theory. The relevant factors to consider in microcapsule design are presented, together with a brief overview of recent techniques for micromech. characterization. The selected methods of the exptl. detn. of mass transport properties, as applied to microcapsules, are summarized. Examples of mass transport characteristics of materials used in cell encapsulation are given. [on SciFinder (R)