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Biomedical subjects

S Ringoir

Publications and source records attributed to S Ringoir.

At least 73 records · Page 4Linked to original sources
PubMed1991

In vivo solute elimination of paired filtration dialysis.

Paired filtration dialysis (PFD) is a new dialysis strategy whereby a hemofilter and a hemodialyzer are coupled in series. It has been assumed that this approach allows a better solute elimination than conventional hemodialysis (HD), allowing a shortening of dialysis time. To evaluate this hypothesis, solute elimination with PFD either with 0.4 m2 polysulphone (PS) and 1.36 m2 cuprophan (CU) 3x3 h/wk, or with 0.4 m2 PS and 1.06 m2 CU 3x4 h/wk, was compared to HD with 1.36 m2 CU, 3x4 hours weekly in the same patients. During PFD, 10L were ultrafiltered and substituted by saline. Overall extraction of UV absorbing solutes (MW less than 10,000 Dalton), and extraction of individual solutes identified by high performance liquid chromatography (HPLC) were compared as well as urea kinetics. For PFD 3x3 h overall extraction of UV-absorbing compounds and of hippuric acid was significantly higher than for HD 3x4 h (p less than 0.05). Overall extraction of UV-absorbing compounds and of all but one individual compound under study was markedly higher for PFD 3x4 h vs conventional HD 3x4 h (p less than 0.01), in spite of a higher diffusive area with the latter technique. No differences in urea kinetics were observed for the 3 strategies. It is concluded that solute extraction during PFD is higher than during HD, if the treatment time is the same. Even if treatment is shortened to 3x3 h weekly, solute extraction with PFD is at least as efficient as with HD.

Biocompatible Materials↗
PubMed1990

Evaluation of renal function before and after intravenous injection of non-cholangiographic water soluble contrast media in rats: preliminary results.

In this preliminary study, water soluble contrast media (CM) were administrated to normal laboratory rats (n = 11) and renal function was monitored before and followed after this challenge. A significant decrease (p less than or equal to 0.001) of the absolute urinary creatinine output, was noted during 3 days after the injection of the CM: the median (M) control value was 0.0313 mumol/min. 100 g body weight (BW) (interquartile range (IR): 0.0014) while the M values the first, the second and the third day were 0.0209 mumol/min. 100 g BW (IR: 0.0141), 0.0198 mumol/min. 100 g BW (IR: 0.0044) and 0.0265 mumol/min. 100 g BW (IR: 0.0054) respectively. The serum creatinine 24 hours after injection was 59,8 mumol/l (IR: 7.92) which is significantly higher (p less than or equal to 0.002) compared to the M serum creatinine of 51.9 mumol/l (IR: 15.0) evaluated in a group of normal unchallenged laboratory rats. These changes are in contrast with the low frequency of renal failure episodes encountered in clinical circumstances. Further experiments with inclusion of a control group receiving a sham injection seem necessary.

Animals↗
PubMed1990

Comparison of two methods for the estimation of urea kinetics and introduction of a third simplified method.

It has been claimed that computed urea kinetic (UK) modelling in hemodialysed patients, for the estimation of protein intake, leads to an overestimation of protein catabolic rate (PCR). In the present study, three different methods of kinetic modelling for the determination of PCR and Kt/V are compared in 24 patients. The first method was the direct quantification method (DDQ) based on the collection of all urea eliminated from the body. The first computed method (ICMI) was the urea kinetic modelling method as described by Sargent. Dialyzer clearances were measured directly and not estimated by theoretical extrapolation. The second computed method (ICMII) is based on the indirect calculation of urea distribution volume (Vu), according to Watson, and of dialyzer clearances from this Vu and from pre- and post-dialysis urea concentrations. All three methods resulted in PCR's that were not significantly different (DDQ: 1.03 +/- 0.19; ICMI: 1.04 +/- 0.22; ICMII: 1.08 +/- 0.25 mg/Kg BW.24 hrs; p greater than 0.05). When the results were correlated, the following results were obtained: ICMI vs ICMII: r = 0.89, p less than 0.001; ICMI vs DDQ: r = 0.68, p less than 0.01; DDQ vs ICMII: r = 0.78, p less than 0.001. Intermutual comparison of Kt/V values resulted in virtually identical results, especially when comparing ICMI and ICMII, where the regression line equalled the identity line. In conclusion, all methods seem equally reliable in determining mean PCR and Kt/V. Our data, obtained with directly measured dialyzer urea clearances, do not confirm the earlier held opinion that computed modelling results in an overestimation of PCR.(ABSTRACT TRUNCATED AT 250 WORDS)

Female↗
PubMed1989

General planning of an artificial organ center.

There is an increasing need for research and development centers to deal with design and evaluation of organ replacement systems, the improvement of older devices, and the study of biocompatibility problems. Special attention, in this article, is focused on the determinant role of the background of the investigators involved in a given center and the selection of research programs to be pursued. Financial and architectural aspects are discussed in general terms. Appropriate planning of artificial organ centers should allow conceptualizing research and development that will exert a practical impact on patient care locally and worldwide.

Animals↗
PubMed1989

Hemodiafiltration.

Explore the source record for details and available documents.

Blood Pressure↗
PubMed1989

[Influence of age on the indications for continuous ambulatory peritoneal dialysis].

A retrospective 10 year analysis of the reasons for admitting patients in a university hospital CAPD or hemodialysis program is performed. More specifically, the influence of age as indicator has been investigated. It appears that since 1983, the CAPD population becomes progressively younger and the hemodialysis population older. This is mainly due to preferential admission in CAPD of young diabetics and because of patients preference. The reasons for dropout and prognosis after transfer to another mode of treatment are discussed.

Adolescent↗
PubMed1989

[A study of the causes of staghorn calculi].

A thorough metabolic evaluation of all staghorn stone patients seems justified, considering the results obtained by the study of 27 such cases. Pak's ambulatory screening test, slightly modified, was used. This allowed the finding of a hypercalciuria in more than 50% of the cases, a hyperuricosuria in 63% of the cases and a hyperoxaluria in one case out of five. A metabolic anomaly was not detected in two patients. Although urinary tract infection, present in 75% of the cases is essential to the genesis of a staghorn stone, the question raises whether metabolic anomalies are not the primary cause of the stone formation.

Adolescent↗
PubMed1988

Development of anti-N-like antibodies during formaldehyde reuse in spite of adequate predialysis rinsing.

The development of anti-N-like antibodies has been demonstrated with formaldehyde reuse of hemodialyzers. It has been recommended to pursue a postrinsing venous effluent formaldehyde concentration in the range of or below 2 to 10 ppm, in order to prevent the development of these anti-N-like antibodies. In the present study, we evaluated formaldehyde reuse in a population of 50 patients and whether the strict control of predialysis effluent formaldehyde concentration below 2 to 3 ppm could prevent the development of anti-N-like antibodies. Five of 50 patients (10%) became positive 6 to 14 months after the start of formaldehyde reuse, indicating that even a careful control of effluent formaldehyde concentration cannot prevent the occurrence of this abnormality.

Adult↗
PubMed1988

Drug protein binding in chronic renal failure: evaluation of nine drugs.

In this study, changes of protein binding of nine drugs were evaluated. In addition, theophylline and phenytoin, the two drugs with the most substantial and progressive decrease in protein binding, were further studied by high performance liquid chromatography (HPLC)-fractions of ultrafiltrate of normal and uremic serum, in an attempt to identify substances causing drug protein binding inhibition. There was a marked decline of the protein binding of theophylline, phenytoin and methotrexate (dialyzed patients vs. normals: -20.1, -16.0 and -15.1%, respectively). There was a rise in the protein binding of propranolol, cimetidine and clonidine. The changes observed for diazepam, prazosin and imipramine were less marked. For phenytoin, theophylline, methotrexate and diazepam, protein binding was inversely correlated to the serum creatinine (r = 0.87, 0.80, 0.79 and 0.67, P less than 0.001), and a less pronounced but still significant positive correlation was found for clonidine (r = 0.46, P less than 0.01). Ultrafiltrate, obtained during a hemofiltration session, inhibited protein binding of theophylline and phenytoin in a dose dependent way. After separation of this ultrafiltrate by HPLC, it appeared that for both theophylline and phenytoin at least a part of this inhibitory activity corresponded to the elution zone of hippuric acid. For theophylline two other inhibitory zones were further recognized: one corresponding to the elution zone of NaCl and one in which the responsible substance remained unidentified. Hippuric acid in solution inhibited protein binding of theophylline and phenytoin in a dose dependent way. In conclusion, protein binding of several drugs currently used in renal failure is affected in parallel with renal function, which might affect the therapeutic effectiveness of the drugs.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Proteins↗
PubMed1988

Single-needle membrane plasmapheresis. In vivo comparison of plasma separator performances.

Plasma filtration characteristics of three hollow fiber plasma separation filters (Plasmaflo Hi-05, Extraplex BL 550 and CPS-10) were studied in a single-needle setting by means of the double headpump. Plasma exchange was carried out in 12 patients during a total number of 59 sessions. For each filter, a mean total ultrafiltration volume of +/- 3,000 ml was obtained over a period from 92 to 121 min. The lowest and highest obtained mean filtration flows were 26.7 +/- 2.5 and 36.6 +/- 1.7 ml/min for Extraplex BL 550 and CPS-10, respectively (p less than 0.01). The pre- and postplasmapheresis pressures, measured in the bubble trap chamber as an indirect estimation of transmembrane pressure, were lower for the Plasmaflo Hi-05 than for the two other filters under study; pressures remained unaltered during the session. Blood pressure showed a minor but significant decline during plasmapheresis with the Plasmaflo filter. A reduction after plasmapheresis by more than 40% of the immunoglobulins IgE, IgG, IgM and IgA, and of complement factors C3 and C4 was seen for each of the filters and no significant differences between the filters were observed. An additional study on 6 filters with constant blood flow and TMP showed minor differences in the transmembrane pressure necessary to obtain a given filtration volume per unit of time and similar sieving coefficients for immunoglobulins. This study demonstrates that with this single-needle technique a satisfying immunoglobulin extraction performance was obtained for each of the filter types studied; however, there existed minor but significant differences in the patient hemodynamic status according to the membrane used.

Blood Pressure↗
PubMed1988

Search for optimizing dialysis therapy. I. Acute effects of hemodiafiltration with a highly permeable membrane and a large dose of convection and diffusion.

Based on the concept that an optimisation of dialysis therapy might be achieved by increasing the removal of small metabolic substances as well as low molecular weight proteins, hemodialfiltration (HDF) was modified. In 9 ESRD patients, HDF was performed acutely for 4 h, where 60 liters of substitution fluid were infused per patient. Two polysulphone F60 membranes in line were used as hemodialfilters. As compared to conventional hemodialysis (HD), performed with a cuprophane dialyser, HDF resulted in higher extraction indices for small solutes assessed by HPLC. Due to the large amount of convection applied, HDF was followed by significant decreases of low molecular weight proteins ranging from 9.5 kdaltons (iPTH, p less than 0.01) to 17 kdaltons (myoglobin, p less than 0.01). Analysis of the protein pattern of the serum revealed a nonlinear function in the decrease of plasma proteins after HDF. It is concluded that even though the detoxification efficacy of the described HDF method is by far superior to conventional HD in quality and quantity, the efficacy is still far from that of excretory renal function. Thus, to further improve efficacy with respect to the catabolic renal function for low molecular weight proteins, membranes for HDF or hemofiltration barriers but should surpass the sieving properties of the glomerulus in the low molecular protein range.

Adult↗