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Biomedical subjects

W Van Biesen

Publications and source records attributed to W Van Biesen.

At least 37 records · Page 2Linked to original sources
PubMed1998

Recent developments in osmotic agents for peritoneal dialysis.

Although glucose is still the most widely used osmotic agent for peritoneal dialysis, it has several disadvantages that challenge its long-term use. During the past years several nonglucose molecules have been tested as osmotic agents for peritoneal dialysis. Most of these molecules have some advantages over glucose, but they also have drawbacks. Every new agent should be carefully tested for performance and long-term safety. In the following review, alternative osmotic agents are discussed, including their potential indications and drawbacks. Major issues include the improvement of biocompatibility and preservation of peritoneal membrane integrity by using dialysate with more physiologic pH, the effect on nutritional status by using dialysate with amino acids, and maintenance of peritoneal ultrafiltration in the long-term by using dialysate with polyglucose. It is believed that in the near future, mixtures of osmotic agents will become most appropriate to obtain the best performance.

Acetylgalactosamine↗
PubMed1998

Experimental models in peritoneal dialysis: a European experience.

BACKGROUND: The development of adequate animal models is important for the in vivo study of selected aspects of peritoneal dialysis (PD) that cannot be evaluated by an in vitro model, such as peritoneal membrane transport, the influence of local defense mechanisms, and for testing new osmotic agents and their biocompatibilities. METHODS: Our experience with animal models for PD, including the acute Stockholm model in non-uremic rats, the acute and chronic Amsterdam model in non-uremic rats, and the chronic Gent model in uremic rats, is described. RESULTS: The Stockholm model proved to be useful in understanding the normal physiology of peritoneal transport, and for testing new dialysis solutions and their biocompatibilities. It is a rather simple and inexpensive model, and thus is suitable for screening new solutions and additives. The Amsterdam model permits the study of chemokines and mesothelial cell regeneration in vivo, and is applied in a model of chronic peritonitis. The results of the Gent model suggest that chronic peritoneal dialysis in uremic rats is feasible for at least eight weeks. This model is, however, very laborious, time consuming, and expensive. CONCLUSION: Further improvement of the technique and increase of the dialysis dose should result in a better and more realistic model for peritoneal dialysis. It is hoped that in the future these models will be useful to test the effects of long-term intraperitoneal application of different dialysis solutions and additives in uremic animals.

Animals↗
PubMed1998

Application of Kohonen neural networks for the non-morphological distinction between glomerular and tubular renal disease.

BACKGROUND: A Kohonen topological map is an artificial intelligence system of the connectionist school (neural networks). The map learns the typical features of the subclasses in the learning set by means of a shortest Euclidean distance algorithm, after which self-adaptation of the neurons occurs. By its ability of self-organization and generalization, a Kohonen map is useful for pattern recognition, and its application in the medical field as an aid for decision making seems promising. This study describes the use of a Kohonen topological mapping system in the classification of renal diseases as being glomerular or tubular on basis of clinical characteristics and laboratory results. METHODS: Forty-one parameters from 75 patients were retrospectively retrieved and used to train four different Kohonen maps of 10 x 10 neurons. For reference diagnostic classification, we referred to the results of the light-microscopic examination. The classification of the patients by the four different Kohonen networks was compared to the classification by a rule-based system and by three nephrologists. We also developed a 'hybrid' decision system that makes a classification on basis of the opinion of the four networks and that of the rule-based system. RESULTS: The results show that a Kohonen map is capable of classifying the patients as having glomerular or tubular disease with a higher sensitivity and predictive value than the nephrologists and the rule-based system, and that the best classification was performed by the hybrid system: sensitivity and predictive value for the diagnosis 'glomerular' respectively 100 and 88% for the network with the most adequate results, 90 and 83% for the nephrologists, 90 and 95% for the rule-based system, and 95 and 96% for the hybrid system; sensitivity and predictive value for the diagnosis 'tubular' respectively 50 and 100% for the neural networks, 31 and 45% for the nephrologists, 81 and 68% for the rule-based system, and 87 and 82% for the hybrid system). CONCLUSION: We conclude that a Kohonen map is capable of classifying the patients as having glomerular or tubular disease with a high sensitivity and predictive value. The rule-based system performs worse than the neural networks. The most adequate results were obtained with the hybrid system.

Adult↗
PubMed1998

Analysis of the reasons for transfers between hemodialysis and peritoneal dialysis and their effect on survivals.

Data on the outcomes of patients who are transferred between hemodialysis (HD) and peritoneal dialysis (PD) are scant. This study analyzes data on patients transferred from their initial modality at the University Hospital Gent between 1978 and 1996 for the reasons for, and outcomes from, the transfer. The reasons for the transfer from HD to PD (n = 35) were access problems (25%), cardiovascular (40%) and blood pressure problems (25%), and personal choice (10%). For the transfer from PD to HD (n = 32) peritonitis (50%), social problems (14%), adequacy or ultrafiltration problems (25%), and leakage (11%) were the reasons. There were no differences in survivals between patients who started on HD and who were transferred to PD, and those who remained on HD (P = 0.4). There were improved survivals for the patients who started on PD and who were transferred to HD compared to those remaining on PD (P = 0.01). It is concluded that transferring problematic HD patients to PD does not improve their survivals, whereas the survival of patients with PD-related complications is improved by transferring them to HD. This is due to the differences in the reasons for transfer, which are PD-related complications in the case of PD patients, and cardiovascular problems in the case of HD patients.

Comorbidity↗
PubMed1998

End-stage renal disease treatment: a European perspective.

There is presently much debate about the optimal flow chart of pre-end-stage renal disease (ESRD) and ESRD patients. This article summarizes two important nonmedical factors that affect the outcome of ESRD patients in Europe: late referral and the structure of the health care system. In a European survey, 30% of patients were referred to a nephrologist less than 1 mo before the start of renal replacement therapy (RRT). This had an impact on the modality choice, as 77.5% of late versus 51.1% of early referrals were started on hemodialysis. Hospitalization at start of RRT was longer in late versus early referrals (15.1 +/- 16.0 versus 27.8 +/- 23.7 d respectively, P < 0.001). There were more patients without antihypertensive medication in the late referral group (28.6% versus 15.5%, P = 0.004), and diastolic BP in this group was higher (83.5 +/- 15.8 versus 74.4 +/- 15.0 mmHg, P = 0.03). One year after the start of dialysis, the number of deaths in the late referrals was higher (26.7 versus 16.4%, P = 0.07) and the number of transplanted patients was lower (4.7 versus 17.5%, P = 0.02). Creatinine clearance at start of RRT was 7.0 +/- 3.5 ml/min in the patients who died during the first year after start of RRT versus 9.5 +/- 3.6 ml/min in those surviving. Only 18% of patients were started with a creatinine clearance > 10 ml/min, as recommended by the Dialysis Outcomes Quality Initiative guidelines. It is concluded that late referral to a nephrologist is still a major problem that has a negative influence on modality choice for peritoneal dialysis, and on morbidity and mortality of ESRD patients.

Europe↗
PubMed1993

Contributing factors to the inhibition of phagocytosis in hemodialyzed patients.

Although polymorphonuclear (PMNL) glucose consumption as an index of metabolic response to phagocytosis in the production of free radical species is depressed in hemodialyzed patients, substantial interindividual differences are registered. Studies evaluating to what variables these differences are related are, however, lacking. In the present study, the relation of several factors to PMNL functional capacity in the breakdown of glucose to CO2 by the hexose monophosphate shunt (HMS) is considered in an individual and multifactorial regression analysis. Starting from a database, collected in 126 stabilized hemodialysis patients, PMNL HMS-response to standard quantities of latex and zymosan was correlated to 14 numerical parameters: time since the start of dialysis, hematocrit, serum creatinine, phosphorus, ferritin, albumin, parathormone, albumin before and after administration of desferrioxamine, residual creatinine clearance, PCR, TACurea, Kt/V and age. In addition, the non-numeric parameters of sex, biocompatibility of dialyzers, and primary diagnosis were also considered. A significant correlation was found for time on dialysis (P < 0.001), hematocrit (P < 0.001), ferritin (P < 0.05), PTH (P < 0.001) and aluminum (P < 0.05). The highest correlation coefficients were found for time on dialysis (latex: N = 126, r = 0.50, P < 0.001; zymosan: N = 126, r = 0.58, P < 0.001). Multivariate correlation analysis of one clinical parameter together with time on dialysis to PMNL response showed that the correlation was strongly weakened or disappeared for ferritin, aluminum and PTH, but not for hematocrit. Our data indicate that time since the start of dialysis is an important, but not unique factor, influencing polymorphonuclear functional capacity in a hemodialysis population.

Bacterial Infections↗
PubMed1993

Depressed phagocytosis in hemodialyzed patients: in vivo and in vitro mechanisms.

Infection is a frequent complication and the major cause of death among end-stage renal patients. Polymorphonuclear phagocytes (PMNL) are important in host defense mainly because of bacterial destruction by nicotinamide adenine dinucleotide phosphate (NADPH) oxidase-related free radical production following phagocytosis. In this study, hexose monophosphate pathway glycolytic activity, delivering energy to NADPH oxidase, is evaluated in vivo and in vitro, in healthy controls and in dialyzed renal failure patients. Our results show a marked parallel and correlated inhibition in the response to three stimuli for phagocytic activity (Staphylococcus aureus, formyl-methionine-leucine-phenylalanine, phorbol myristic acid) in predialysis samples. These data point to a main suppression of metabolic pathways, possibly beyond protein kinase C. This response is further suppressed at the 15th minute of cuprophane dialysis, for all stimuli studied (-40 to -94%; p < 0.001) except PMA. PMNL response remains intact during dialysis with non-complement-activating dialyzers. In vitro experiments confirm decreased PMNL glycolytic activity after the suspension of cuprophane fragments in normal whole blood. We conclude that polymorphonuclear cell energy delivery to NADPH oxidase is impaired in patients with end-stage renal failure. The impaired response against various stimuli is different in predialysis blood samples compared to samples collected during cuprophane dialysis, and may be related to two different conditions. These events probably contribute to the acquired immune suppression of uremia and the high incidence of infection among dialysis patients.

Cellulose↗
PubMedDate not supplied

Bed-side blind insertion of peritoneal dialysis catheters.

Access to the peritoneal cavity is an essential factor for successful peritoneal dialysis. The technique of catheter insertion can influence technique success and patient satisfaction. As compared to conventional surgical laparotomy, a bedside blind insertion technique under local anaesthesia has logistical advantages for the patient, the hospital and the community. This study compares outcomes of both methods in a single centre. A retrograde analysis of a prospectively collected database on all catheters implanted at the University hospital Ghent between 1/1/1998 and 31/5/2002 was carried out. During this period, catheters were implanted either by conventional laparotomy (CL) or by a bedside blind insertion technique (BI) under local anaesthesia.

Adult↗
PubMedDate not supplied

The role of peritoneal dialysis as the first-line renal replacement modality.

Twenty years after its introduction, peritoneal dialysis (PD) is a well-established alternative to hemodialysis (HD) as a modality of renal replacement therapy. Much debate and research is apparent in the literature, comparing hemodialysis and PD as "opposite" modalities and trying to ascertain which modality should be more optimal. In our opinion, HD and PD are two distinct modalities, each with its own advantages and disadvantages. In addition, it is clear that for both HD and PD, rates of technique failure are high, causing patients to transfer between modalities. The question is thus not which modality is best, but rather, which flow-chart of modalities makes best use of the advantages of each modality, while avoiding its disadvantages. In this respect, HD and PD appear to be complementary modalities. The better preservation of residual renal function, lower risk of infection with hepatitis B and C, better outcome after transplantation, preservation of vascular access, and lower costs are arguments to promote PD as a good initial treatment. When PD-related problems arise (adequacy, ultrafiltration, peritonitis, patient burnout), a timely transfer to HD has to be planned. This editorial tries to review arguments supporting the complementary nature of both modalities, and especially the role of PD as the first-line renal replacement therapy.

Costs and Cost Analysis↗