Biomedical subjects
T Folden
Publications and source records attributed to T Folden.
Clinical evaluation of a peritoneal dialysis kinetic modeling set.
A closed system kinetic modeling set (KMS) has been fabricated which permits collection of a small 100-mL aliquot from each exchange. The KMS was used to collect aliquots from 65 exchanges in 13 patients. The concentrations of urea nitrogen (UN), creatinine (Cr), glucose (G), and total protein (TP) were measured in each individual aliquot (Cka) and drain bag (Cba), and all aliquots for each dialysis treatment were used to calculate the concentrations expected in total batched dialysate (BaC) for the treatment and were compared to the measured concentrations (BaM) in mixed total dialysate. The ratios Cka/Cba [mean+/- two times coefficient of variation (mean +/- 2CV)] were 1.00 +/- 5%, 1.00 +/- 5%, 1.01 +/- 10%, and 1.00 +/- 6%, respectively, for UN, Cr, G, and TP (each, n = 61). The ratios BaC/BaM (mean +/- 2CV) were 1.00 +/- 2%, 1.00 +/- 5%, 1.01 +/- 3%, and 0.99 +/- 5%, respectively, for UN, Cr, G, and TP (each, n = 15). We concluded that the KMS aliquots can be reliably used for kinetic and total clearance calculations without mixing and transporting large volumes of dialysate.
Single-pass continuous flow peritoneal dialysis using two catheters.
With a renewed interest in continuous flow peritoneal dialysis (CFPD), our standard practice of implanting a second catheter in those patients facing access failure provided us the opportunity to perform acute studies on CFPD in these patients, since it temporarily provided us with two catheters. Four patients were studied, with a total of five studies performed. A standard protocol was followed utilizing 1.5% dextrose solution, a 2 L fill, an inflow rate of 200 ml/min with a proportionate outflow for a 4-hour session. A full drain was performed at the end of the study. Our results provided us with a mean effective peritoneal clearance for urea (KpeU) and creatinine (KpeCr) of 40 ml/min and 28 ml/min, respectively, and a mean ultrafiltration rate (Qf) of 13.4 ml/min. Our average mass transfer coefficient (MTC) for urea was 40 ml/min, consistent with kinetic modeling and historical data. The Kpe, MTC, and Qf achieved are significantly higher than other investigators, which could possibly be explained by those obtained by two separate catheters resulting in adequate mixing of the dialysate. These clinical results provide a solid foundation for the future development of this PD modality.
Clinical experience with continuous flow and flow-through peritoneal dialysis.
Concern over the inherent inefficiency of solute removal by conventional peritoneal dialysis (PD) has led to renewed interest in continuous flow PD (CFPD). We present clinical data from two experiences with CFPD. In the first, two catheters were used to recirculate a fixed intraperitoneal volume through an external circuit comprised of a standard hemodialysis system. The second patient had a dual-lumen PD catheter and was studied during two sessions of flow-through PD (FTPD) using sterile PD solution. Urea clearances with both techniques were around 30 ml/min, which is consistent with data reported in the literature. Significant streaming of dialysate from port to port within the peritoneal cavity limited clearances. CFPD offers a potentially safe and effective alternative to daily or nightly home hemodialysis.
Measurement of blood access flow rate during hemodialysis from conductivity dialysance.
An on line clearance monitor automated for measurements of conductivity dialysance (Dcn) was used to measure blood access flow rate (cnQac) during hemodialysis. From mathematical analysis of transport, it was shown that cnQacc = [(Dcn*Decn)/(Dcn - Decn)] [1/bwf], where Dcn is measured with standard cocurrent flow of dialyzer blood (Qb) and Qac; Decn is measured with countercurrent Qb/Qac; and bwf is fractional blood water content. An identical equation was derived to measure Qac from urea dialysance (uQac, Du, Deu). In vitro studies showed excellent correlation between volumetric measurement of Qac (vQac) and cnQac, r = 0.98, n = 29, and between uQac and cnQac, r = 0.97, n = 28. In vivo studies showed comparable agreement between uQac and cnQacc, r = 0.97, n = 14. In two of the patients studied, there was unsuspected severe midgraft stenosis (no recirculation in cocurrent flow) with a Qac of 89 and 202 ml/min disclosed by both cnQac and uQac measurements. Mathematical analysis also showed that when Qb is greater than Qac and there is recirculation in cocurrent flow, the above equations always return the value Qac = Qb. An equation was derived to calculate cnQac without reversal of blood lines in this case, using Dcn calculated from the dialyzer transport coefficient and flow rates.