PubMed · 8967625
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Iu V Nikiforov, I E Chudakov. [Continuous hemodiafiltration].. https://pubmed.ncbi.nlm.nih.gov/8967625/
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Conventional peritoneal dialysis fluids (PDFs) lead to formation of advanced glycation end-products (AGE) in the peritoneal membrane. In this study, we investigated in vitro the dependence of AGE formation on regular changes of PDFs, as performed during continuous ambulatory peritoneal dialysis (CAPD), and on the contribution of high glucose concentration versus glucose degradation products (GDPs). Under conditions similar to CAPD, protein glycating activity of a conventional single chamber bag PDF (CAPD 4.25%), two double chamber bag PDFs (CAPD Balance 4.25% and CAPD Bicarbonate 4.25%) and a sterile filtered control was measured in vitro by N(epsilon)-(carboxymethyl)lysine (CML) and imidazolones, two well characterized, physiologically relevant AGE structures. Regular changes of PDFs increased AGE formation (CML 3.3-fold and imidazolone 2.6-fold) compared to incubation without changes. AGE formation by CAPD 4.25% was increased compared to control (imidazolones 7.9-fold and CML 3.3-fold) and the use of double chamber bag PDFs led to a decrease of imidazolones by 79% (CAPD Bicarbonate 4.25%) and by 66% (CAPD Balance 4.25%) and to CML contents similar to the control. These results indicate that a major part of AGEs were formed by GDPs in PDFs, whereas only a minor part was due to high glucose concentration. The use of double chamber bag fluids can reduce AGE formation considerably.
BACKGROUND: Ionic dialysance may be equivalent to blood-water urea clearance corrected for recirculation (effective urea clearance); however, this is controversial. The aims of our study were (1) to verify in vivo whether the value of ionic dialysance is affected by the method of determination, given the effect of cardiopulmonary recirculation on inlet plasma water conductivity when the inlet dialysate conductivity is changed; and (2) to define the operative modalities for determining ionic dialysance to obtain an adequate estimate of effective urea clearance. METHODS: Thirty-three hemodialysis patients were studied during 186 dialysis sessions with low-flux polysulfone dialyzers using a modified Fresenius Medical Care 4008 B machine equipped with meters to measure inlet and outlet dialysate conductivities. This machine varied inlet dialysate conductivity (Cdi) according to the following pattern: starting from baseline (step 0), Cdi was increased by 8% (step 1). After Cdi had reached the target value, which took 8 to 10 minutes, it was lowered to 8% below the baseline value (step 2). After 8 to 10 minutes, when Cdi had reached the new target, it was returned to its starting value (step 3). Four values of conventional ionic dialysance (using the standard formula) and actual ionic dialysance (taking into account cardiopulmonary recirculation) were obtained for each cycle and were compared among them and with effective urea clearance (Kde). RESULTS: Mean conventional dialysance values at steps 0 to 2 and 2 to 3 (190 and 189 mL/min) were similar and higher than those at steps 0 to 1 and 1 to 2 (171 and 181 mL/min). Mean conventional ionic dialysance values underestimated Kde, particularly at steps 0 to 1 (-22.2 mL/min, P < 0.001) and 1 to 2 (-12.6 mL/min, P < 0.001). The actual dialysance values underestimated Kde by no more than 4.3 mL/min (P < 0.001). In steps 0 to 1 and 1 to 2, the underestimate of Kde by conventional dialysance increased at higher values of Kde, but this relationship did not exist when considering actual dialysance. CONCLUSIONS: The value of ionic dialysance is affected by the method of determination, given the effect of cardiopulmonary recirculation on inlet plasma water conductivity when inlet dialysate conductivity is changed. As a consequence, to provide a correct and direct estimate of effective urea clearance, ionic dialysance must be determined by changing inlet dialysate conductivity in such a way as to keep inlet plasma water conductivity constant by means of two symmetrical high and low dialysate conductivity steps.
It is difficult for conventional hemodialysis to remove albumin-binding uremic toxins (ABUTs) even though they are low molecular weight substances. We investigated the efficiency of albumin-dialysate (AD) for removal of ABUT. Phenols and indoxyl sulfate were selected as ABUT. In vitro dialysis was performed for 2 h in the closed circuit with ABUT containing plasma as a test solution using conventional dialysate (CD) or AD. By the use of CD, the ABUT concentration in the test solution only was reduced by 20 to 30%. On the other hand, AD caused a marked reduction and an increase in test solution and dialysate concentration of ABUT, respectively. ABUT in AD could be adsorbed effectively by activated-charcoal column; accordingly, the ABUT concentration in the test solution continued to decrease throughout the study period. These results suggest that AD could remove ABUT more efficiently than CD, and AD may be useful for reducing accumulated ABUT levels.