Effectiveness of Various Chemical Disinfectants versus Cleaning Combined with Heat Disinfection on Pseudomonas Biofilm in Hemodialysis Machines

The development of bacterial biofilms in the hydraulic circuit of hemodialysis machines is routinely prevented by frequent use of a variety of chemical and heat disinfection strategies. This study compared the effectiveness of several chemical disinfectants, commonly used either alone or in combination with a treatment regimen that involved cleaning plus heat disinfection using an in vitro Pseudomonas biofilm model. Effectiveness of these procedures was evaluated using total and viable biomass quantitation and polysaccharide and endotoxin determination. The chemical disinfection procedures were only partially successful in removing all biofilm components. Heat disinfection alone killed viable biofilm bacteria, but did not remove all the biomass components, including endotoxin. The combination of cleaning with citric acid followed by heat disinfection was the most effective in eliminating all biofilm components from the hydraulic circuit of the in vitro model.

Combined nutritional support and continuous extracorporeal removal therapy in the severe acute phase of maple syrup urine disease

OBJECTIVE

The authors assessed the efficiency, tolerance and outcome of neonates and children with maple syrup urine disease (MSUD) in acute decompensation managed by endogenous and extracorporeal removal of accumulated MSUD metabolites.

DESIGN

Single center cohort study.

SETTING

Pediatric and neonatal intensive care unit in a tertiary care hospital.

PATIENTS

Between January, 1991, and June, 1999, six neonates and six children in acute decompensation of MSUD were included in the study. Each of them had two of the three following criteria: comatose state, gastrointestinal intolerance, leucine plasma levels over 1700 micromol/l.

INTERVENTIONS

Patients were treated by combined nutrition manipulation and continuous venovenous extracorporeal removal therapies (CECRT) including hemofiltration, hemodialysis or hemodiafiltration. A clinical and biological evaluation was performed before, during and following the treatment.

RESULTS

Eleven out of the 12 patients survived. One child had two acute episodes at 6.5 and 9 years old. Eight patients recovered a normal cerebral performance category score. In all cases, plasma leucine level decreased according to a logarithmic mode within 11-24 h hemodiafiltration combined with nutritional support whereas, with nutrition alone after stopping CECRT, the decrease in leucine plasma levels was slower, following a linear mode. Eight patients were supplemented with valine and isoleucine for mean plasma values of 177+/-92 and 68+/-66, respectively.

CONCLUSION

In severe acute decompensation of MSUD, CECRT combined with nutritional support limit central nervous system damage, by dramatically decreasing branched chain amino and keto acid levels.

[Indications and preparations for kidney dialysis]

Every patient with end-stage renal failure, at any age and whatever the type of renal disease, is a legitimate candidate to maintenance dialysis. Contraindications are infrequent and based purely on medical considerations, such as profound and irremediable alteration of physical and/or mental condition. In patients regularly managed dialysis is decided electively on the basis of laboratory criteria in the absence of clinical uremic manifestations other than fatigue, anorexia or nausea. The most widely accepted criterion is a level of creatinine clearance estimated by the Cockcroft-Gault formula between 7 and 10 mL/min/1.73 m2. Psychological preparation of the patient to dialysis is essential and should not be delayed until the advanced stage. Medical preparation involves prophylactic vaccination against virus B hepatitis and creation of a native arteriovenous fistula when hemodialysis is the scheduled option. Every patient should receive in time clear and complete information on the various technical methods of dialysis, in order to allow him an informed choice.

[Epidemiology of end-stage kidney failure in the Ile-de-France: a prospective cooperative study in 1998]

A prospective epidemiological study was conducted from January 1 to December 31, 1998 in the Ile-de-France district to determine the incidence and the prevalence of end-stage renal disease (ESRD) and the characteristics of the patients. All nephrology and dialysis units of the Ile-de-France district participated in the study. The total number of ESRD patients requiring maintenance dialysis was 1155 (including 86 kidney graft failures and 29 children) for a total population of 10.7 millions inhabitants, or 108/10(6)/year. The incidence of new ESRD patients was 100/10(6)/year. The mean age of first-dialyzed, adult patients was 59.8 +/- 16.8 years, with 21.6% aged > or = 75 years. Vascular renal diseases accounted for 22.5% and diabetic nephropathy for 20.6%. As a whole, 36.5% of patients were referred to the nephrologist less than 6 months before starting dialysis. In the latter, the median duration of hospitalization was 28 days, compared to only 3 days in patients cared for by the nephrologist for at least 6 months. Prevalence of patients on maintenance dialysis in the Ile-de-France district grew from 417 to 433/10(6) from the beginning until the end of year 1998, an increment of 3.8%, with an increase in the number of patients treated out-center by self-care hemodialysis or peritoneal dialysis.

Beneficial influence of recombinant human erythropoietin therapy on the rate of progression of chronic renal failure in predialysis patients

BACKGROUND

Partial correction of anaemia with recombinant human erythropoietin (rHuEpo) has been shown to markedly improve the general condition and quality of life of predialysis patients, but the effects of rHuEpo therapy on blood pressure and the rate of progression of chronic renal failure (CRF) are still disputed. In particular, no study evaluated the time duration until the start of maintenance dialysis in treated patients, compared to untreated predialysis patients.

METHODS

We retrospectively evaluated the rate of decline of creatinine clearance (Delta Ccr) and the duration of the predialysis period in 20 patients with advanced CRF treated with rHuEpo (Epo+ group), and in 43 patients with a similar degree of CRF but with less marked, asymptomatic anaemia, not requiring rHuEpo therapy (Epo- group). All patients were submitted to identical clinical and laboratory surveillance. All received similar oral supplementation with B(6), B(9), and B(12) vitamins and oral iron supplementation. Maintenance dose of subcutaneous epoetin was 54.3+/-16.5 U/kg/week (median dose 3300 U/week).

RESULTS

Initial and final haemoglobin (Hb) levels were 8.8+/-0.7 and 11.3+/-0.9 g/dl in the Epo+ group, vs 10.9+/-1.2 and 9.5+/-0.9 g/dl in the Epo- group. In the Epo+ group, Delta Ccr declined from 0.36+/-0.16 during the preceding 24 months to 0.26+/-0.15 ml/min/ 1.73 m(2)/month after the start of rHuEpo therapy (P<0.05). No significant variation was observed in the Epo- group. Time duration until the start of dialysis was 16.2+/-11.9 in the Epo+ group, compared to 10.6+/-6.1 months in the Epo- group (P<0.01). Slowing of progression was observed in 10 Epo+ patients, whereas no significant variation in Delta Ccr occurred in the other 10. There was no difference in previous Delta Ccr rate, nor in Hb or blood pressure levels while on rHuEpo therapy between the two subgroups.

CONCLUSIONS

Our study affords conclusive evidence that rHuEpo therapy did not result in accelerated progression of CRF in any treated predialysis patients, nor deleterious increase in blood pressure, but instead resulted in significant slowing of progression and substantial retardation of maintenance dialysis. Such encouraging results remain to be validated in a large prospective, randomized study.

Epidemiology of end-stage renal disease in the Ile-de-France area: a prospective study in 1998

BACKGROUND

The objective of this study was to determine the incidence and prevalence of end-stage renal disease (ESRD) requiring maintenance dialysis in the Ile-de-France district (Paris area), and the characteristics of patients at start of dialysis.

METHODS

This is a prospective epidemiological study with the cooperation of all dialysis facilities of the Ile-de-France district (population 10.7 million inhabitants as of March 1999). All consecutive ESRD patients who started dialysis from January 1 to December 31 1998, with demographic and clinical characteristics, and of the total number of patients on dialysis with their distribution according to dialysis modality were recorded.

RESULTS

The total number of ESRD patients in 1998 was 1155, including 29 (2.5%) children aged < or =17 years and 86 (7.4%) returns to dialysis following kidney graft failure. Incidence of first-dialysed patients was 100 per million population (p.m.p.) and overall incidence, including returns from transplantation, was 108 p.m.p. The mean age of first-dialysed adult patients was 59.8+/-16.8 years, with 21.6% aged > or =75 years. Patients with vascular renal disease were 22.5% and those with diabetic nephropathy 20.6%. As a whole, 36.5% of patients were referred to the nephrologist < or =6 months before start of dialysis, including 32.2% referred < or =1 month before starting. Prevalence of cardiovascular disease was nearly twice as high in patients referred <6 months of starting dialysis than in those who benefited from effective nephrological care for >3 years in the predialysis period. By multivariate analysis, this difference persisted after adjustment for age and other confounding covariates. The total number of patients on maintenance dialysis increased from 417 to 433 p.m.p. (a yearly 3.8% increase) from the beginning to the end of 1998.

CONCLUSION

This recent epidemiological study in a large French urban area indicates an annual incidence of 100 new ESRD patients p. m.p., with a high proportion of older, vascular and diabetic patients. Overall incidence, including returns from transplantation, reached 108 p.m.p. Cardiovascular disease was significantly less frequent in patients who received nephrological care for > or =3 years prior to start of dialysis than in late referred patients, underlining the benefits of early nephrological management of renal patients.

[Incidence of end-stage renal disease in Ile de France: a prospective epidemiological survey]

OBJECTIVES

To evaluate incidence and prevalence of patients with end-stage renal disease (ESRD) treated with maintenance dialysis in the Ile de France district in 1998.

METHODOLOGY

Prospective epidemiologic inquiry with the cooperation of the 91 nephrology departments and dialysis facilities of the Ile de France district (total population: 10,695,300 inhabitants in March 1999), from January 1st to December 31st, 1998. Evaluation of the demographic and clinical characteristics of the 1155 patients accepted on maintenance dialysis in 1998, and recording of the total number of dialyzed patients at the beginning and at the end of the same year.

RESULTS

The total number of ESRD patients was 1155, including 29 (2.5%) children aged < or = 17 years and 86 (7.4%) returns to dialysis following kidney graft failure. Incidence of ESRD in first-dialyzed patients was 100/million/year and overall incidence, including returns from transplantation, was 108/million/year. Mean age of the 1040 adult first-dialysis patients was 59 +/- 16.8 years, with a proportion of those aged > or = 75 years of 21.6%. Patients with vascular renal disease were 22.5% and those with diabetic nephropathy 20.6%. As a whole, 36.5% of patients were referred to the nephrologist < 6 months of starting dialysis. Prevalence of patients on supportive dialysis increased from 417 to 433 per million inhabitants (a 3.8% increase) from the beginning to the end of 1998, with the proportion of patients treated with self-care dialysis or peritoneal dialysis rising by 10%. From January 1995 to January 1999, prevalence of dialysis-treated ESRD patients rose by nearly 4% per year as a mean.

CONCLUSION

Incidence of ESRD patients requiring maintenance dialysis in the Ile de France district reached 100/million in 1998, an increment of 4% per year over the past 4 years. The increase in incidence results from the increasing number of older patients, parallel to the ageing of general population, these patients having a high comorbidity mainly due to diabetes and atherosclerosis. Prevalence of dialysis-treated patients was 433/million population at the end of 1998. It rose at a similar rate as did incidence, although with a growing proportion of out-center dialysis.

Dyslipidaemia and the progression of renal disease in chronic renal failure patients

BACKGROUND

Dyslipidaemia is common in patients with chronic renal failure (CRF), and there is increasing evidence to support the role of dyslipidaemia as a contributing factor in the progression of chronic renal disease. However, few prospective studies have been carried out which address the possible relationship between dyslipidaemia and the rate of progression of renal disease in patients with renal failure.

METHODS

Between January 1985 and December 1997, we prospectively assessed the risk of CRF progression to dialysis in a cohort of 138 patients. Forty CRF patients reached end-stage renal disease (ESRD) and had to start supportive therapy during the follow-up period [group ESRD(+)]. The remaining 98 CRF patients served as controls [group ESRD(-)]. Potential clinical and laboratory risk factors for more rapid CRF decline to dialysis, including lipid abnormalities and baseline creatinine clearance were determined at the start of the follow-up period.

RESULTS

Several significant differences were found in univariate analysis between the two groups of CRF, ESRD(+) and ESRD(-), namely a shorter follow-up period, a lower level of baseline creatinine clearance, a faster rate of creatinine clearance decline, a higher level of serum triglycerides, fibrinogen, total homocyst(e)ine and proteinuria, and a lower level of serum high-density lipoprotein in the ESRD(+) group than in the ESRD(-) group. However, by multivariate Cox analysis proteinuria [relative risk (95% confidence interval) 1.32 (1.16-1.50) for each g/day P = 0.001], baseline creatinine clearance [0.53 (0.40-0.70) for each 10 ml/min, P = 0.001] and chronic interstitial nephritis and hypertensive nephrosclerosis [0.38 (0.17-0.84) for presence, P = 0.005] were the only significant risk factors for CRF progression to dialysis. Hypertriglyceridaemia and male gender were selected in the final model, but were of borderline significance.

CONCLUSIONS

These results suggest a limited role for dyslipidaemia in the progression of chronic renal disease to dialysis in CRF patients, in contrast with the powerful influence of proteinuria, baseline creatinine clearance and nephropathy type in predicting this progression.

Incidence of atherosclerotic arterial occlusive accidents in predialysis and dialysis patients: a multicentric study in the Ile de France district

BACKGROUND

An abnormally high mortality from atherosclerotic cardiovascular (CV) accidents has long been reported in patients on maintenance haemodialysis (HD). However, incidence of atherosclerotic CV accidents had not been so far assessed in predialysis patients. In order to evaluate the respective influence of uraemia and the dialysis procedure, we compared incidence of atherosclerotic accidents before and after initiation of HD in a large population of patients.

STUDY DESIGN

A total of 748 patients (411 male) were included in a retrospective study based on anamnestic data of patients living on maintenance haemodialysis in March 1993 in nine dialysis units of the Paris area. Incidence of first myocardial infarction (MI) or cerebral infarction (CI) was calculated by reference to the number of years of exposure to the risk both before and after initiation of HD in the various age groups.

RESULTS

Overall, 103 first atherosclerotic accidents were recorded, including 10 CI (7 in males) and 93 MI (68 in males). Of the latter, 39 occurred before and 54 after start of HD, at a mean (+/-SD) age of 62.4+/-9.9 and 63.7+/-11.1 years respectively. The annual incidence of MI in males was 8.0, 19.5 and 28.3/1000 patient-years, before and 18.8, 21.6 and 29.9 patient-years after start of HD in the age groups 45-54.9, 55-64.9 and > or = 65 years respectively, compared to figures of 3.4, 7.5 and 10.4/1000 subject-years in the corresponding age groups in the general French population.

CONCLUSION

Incidence of atherosclerotic CV accidents is nearly three times higher in uraemic patients than in the general population in the same age range in both genders. The fact that incidence and age at onset of first MI was similar in predialysis and in dialysed patients suggests that the uraemic state per se is a main determinant of such accelerated atherosclerosis.

Evidence of bacterial biofilm in tubing from hydraulic pathway of hemodialysis system

Biofilms consist of microorganisms immobilized at a substratum surface embedded in an organic polymer matrix of bacterial origin. Tubing drawn from the fluid pathways within dialysis machines of various models were investigated for biofilm. Scanning electron microscopy (SEM), performed on approximately 2 cm2 samples of the tubing inner surfaces revealed that the inner surfaces of the tubing were covered with biofilms consisting of numerous deposits and glycocalix at different stages of formation with components containing bacteria and algae. Evaluations of biomass were performed from tubing sections of various lengths and inner diameters put in tubes containing water for injection and immersed in an ultrasound washtub for 1 h to ensure sloughing of the biofilm. Living bacteria were identified by plating on nutrient agar media and incubation for 48 h at 37 degrees C. Epifluorescent stains were used for the total bacteria count. Lipopolysaccharide levels were determined by the endotoxin activity measurements. Polyoside contents were determined by the colometric method, and the chemical oxygen demand was measured to evaluate the amount of organic substance. Biofilms detached from tubing samples drawn from the water path, bicarbonate path, and fresh dialysate path within dialysis machines contained approximately 1.10(3)-1.10(6) total bacteria/cm2, yet only some living bacteria were found. Endotoxin levels ranged from 1 to 12 EU/cm2. In contrast in the dialysate fluid, no bacteria were found, and the endotoxin content was under the detection level of the method. The polyoside content and chemical oxygen demand of the biomass ranged from 11 to 83 microg/cm2 and from 53 to 234 mg/cm2, respectively. It is concluded that a germ- and endotoxin-free dialysate does not exclude the risks and hazards of bacteria and endotoxin discharge from biofilm developed on the fluid pathway tubing, acting as a reservoir for continuous contamination, and efforts in the optimization of cleaning and disinfection procedures used for hemodialysis systems should aim to detach and neutralize biofilm when necessary.

Substitution of acetic acid for hydrochloric acid in the bicarbonate buffered dialysate

In a multicenter study including 5 dialysis units, blood acetate changes during 4 h dialysis sessions in 141 patients treated with a 4 mM acetate-containing bicarbonate dialysate (ABD) were evaluated and compared to the values of 114 patients using an acetate-free bicarbonate dialysate (AFD). Acetate-free bicarbonate dialysate was delivered by a dialysis machine from the mixing with water for dialysis of a 1/26.2 bicarbonate concentrate, and a 1/35 acid-concentrate in which acetic acid was substituted for hydrochloric acid (Soludia, Fourquevaux, France). This new type of dialysate was routinely in use for 3 years on average (range, from 2 to 5 years). All patients fasted before and during dialysis. Blood samples were withdrawn at the start and at the end of dialysis sessions. The acetate plasma concentration was determined using the acetyl-CoA synthetase enzymatic method (Boehringer, Manheim, Germany). In patients treated with ABD whose predialysis blood acetate levels were in the physiologic range of < or = 100 microM (n = 113), the acetate plasma concentration increased from a predialysis mean value of 22+/-3 microM to a postdialysis mean value of 222+/-11 microM in 88 patients (78% of patients) whereas the acetate plasma concentration changes remained in the range of physiologic values from 21+/-6 to 58+/-7 microM in the other 25 patients. In contrast, patients treated with AFD whose predialysis blood acetate levels were in the physiologic range (n = 108), acetate plasma concentration increased from a predialysis mean value of 49+/-6 microM to 160+/-19 microM in only 13 patients (12% of patients) whereas acetate plasma concentration changes remained in the range of physiologic values of 23+/-2 to 41+/-3 microM in most of the patients of this group. In this study, a significant number of patients, whether receiving standard or acetate-free bicarbonate dialysates, exhibited an extremely high acetate plasma concentration at the start of the dialysis session. Hyperacetatemia was controlled with AFD in patients whose predialysis acetate plasma concentration of 316+/-82 decreased to 55 +/-23 microM (n = 6) at the end of the dialysis session whereas the acetate plasma concentration remained high when the predialysis concentration was 580+/-76 microM, with a postdialysis concentration of 233+/-39 microM (n = 28). It is concluded that in patients whose predialysis blood acetate levels were in the physiologic range, acetate-containing bicarbonate dialysate induces hyperacetatemia whereas postdialysis blood acetate remains in the normal range in such dialysis patients treated with acetate-free dialysate. Chronic hyperacetatemia, which could be found in dialysis patients, is well controlled by dialysis using an acetate-free dialysate.

[Incidence of atherosclerotic cardiovascular events in patients with chronic uremia: epidemiologic studies in Ile-de-France]

An abnormally high mortality from atherosclerotic cardiovascular (CV) accidents has long been reported in patients on maintenance hemodialysis (HD). However, incidence of such complications had not been so far evaluated in chronic renal failure (CRF) patients not yet on dialysis. In a cohort study bearing on 232 predialysis CRF patients, followed as out-patients at Necker hospital, incidence of first myocardial infarction (MI) was three times higher than in the French general population in every age group and in both genders, with a mean (+/- SEM) age at onset of MI of 62.9 +/- 1.2 years. In a retrospective cooperative study involving 748 patients treated in 9 hemodialysis centers in the Ile-de-France area, incidence of first MI episodes did not differ before and after start of HD therapy and was similar to that observed in the cohort study. Mean age of patients at first MI, before and after start of HD, was respectively 62.4 +/- 1.6 and 63.7 +/- 1.5 years, a not significant difference. In conclusion, two epidemiologic studies confirm the existence of accelerated atherosclerosis in CRF patients, the incidence of MI being 3 times higher in uremic patients than in the general population in every age group and in both genders. The fact that incidence of first MI episodes and age at onset was similar in predialysis and in dialyzed patients suggests that the uremic state per se is a main determinant of such accelerated atherosclerosis. It results that therapeutic measures aimed at preventing development of atherosclerosis should be initiated from the early stage of CRF, long before start of renal replacement therapy.

Continuous venovenous hemodialysis in a neonate model: a two-pump system

OBJECTIVE

To evaluate the efficiency and tolerance of venovenous hemofiltration, hemodiafiltration, and hemodialysis with a two-pump system in a neonatal animal model of acute renal failure.

DESIGN

Prospective trial.

SETTING

Animal laboratory at a large university-affiliated medical center.

SUBJECTS

New Zealand white rabbits, weighing 3325 +/- 380 g.

INTERVENTIONS

Venovenous hemofiltration, hemodiafiltration, and hemodialysis were performed in anesthetized rabbits with previous bilateral ureteral ligation.

MEASUREMENTS AND MAIN RESULTS

At a blood flow rate of 19 +/- 0.5 mL/min, we determined hematocrit, urea, creatinine, and electrolyte values in blood, at the inlet and outlet of the hemofilter, and in ultrafiltrate at the start and after 15, 30, 60, 90, 120, and 180 mins of hemofiltration (ultrafiltrate flow rate of 1.9 +/- 0.2 mL/min), hemodiafiltration (dialysate plus ultrafiltrate flow rate of 16.9 +/- 0.8 mL/min), and hemodialysis (dialysate flow rate of 15.7 +/- 1.1 mL/min). Arterial blood pressure, heart rate, and body temperature were monitored during the procedures. Urea and creatinine instantaneous clearances were higher with hemodiafiltration (8.0 +/- 0.7 and 6.2 +/- 0.7, respectively, n = 29) and hemodialysis (6.8 +/- 1.1 and 4.8 +/- 0.9, respectively, n = 31) than with hemofiltration (1.8 +/- 0.6 and 1.9 +/- 0.4, respectively, n = 16). Initial and final weights, temperatures, and hematocrit, sodium, and protein blood concentrations of each 180-min procedure were similar.

CONCLUSIONS

Hemodiafiltration had a higher urea removal rate than hemodialysis but the management of hemodiafiltration was more cumbersome and time consuming in the absence of a flow equalizer device. As a result, we recommend continuous venovenous hemodialysis as the therapy of choice.

[Benefits of early nephrological management of chronic renal failure]

OBJECTIVES

We evaluated whether early nephrological referral of patients with chronic renal failure (CRF) resulted in improved condition of patients at initiation of maintenance dialysis and in better outcome on dialysis.

PATIENTS AND METHODS

We prospectively recorded clinical status, laboratory parameters, length of hospital stay and outcome of 900 CRF patients who started maintenance dialysis at Necker hospital between January 1989 and December 1996. We compared patients who benefited regular nephrological follow-up, and patients who were referred in emergency conditions at the ultimate stage of CRF.

RESULTS

Among the 900 patients, 731 (81.2%) had regular nephrological follow-up, including 632 (70.2%, group IA) with optimal preparation to dialysis and 99 (11%, group IB) whose clinical course was complicated due to heavy comorbidity, whereas 169 (18.8%, group II) had no previous nephrological management. Over the 8-year observation period, the proportion of the latter group did not decrease. Late referred patients had higher blood pressure level, more frequent fluid overload, higher serum levels of urea, creatinine, uric acid and phosphate, and lower levels of bicarbonate, calcium, albumin and creatinine clearance that did well-prepared patients. Mean (+/- SD) hospital stay was 29.7 +/- 15.8 days in the former compared to only 4.8 +/- 3.3 days (p < 0.001) in the latter. Early deaths within 3 months of dialysis initiation were more frequent (7.1 vs 1.6% p < 0.05) and less patients subsequently were able to be treated out-center (20.1 vs 40.7%, p < 0.05) in group II than in group IA. The overcost induced by late referral may be estimated at 0.25 million French francs per patient.

CONCLUSION

An unjustified late nephrological referral of CRF patients still is observed in nearly 20% of cases. Such late referral is detrimental to both patients in terms of altered quality of life and long hospital stay, and to the collectivity due to heavy overcost. Closer cooperation between family physicians and nephrologists is needed to provide optimal management and allow timely preparation to maintenance dialysis of CRF patients.

Incidence and risk factors of atherosclerotic cardiovascular accidents in predialysis chronic renal failure patients: a prospective study

BACKGROUND

Accelerated atherosclerosis resulting in an abnormally high incidence of coronary and cerebrovascular occlusive accidents has been repeatedly reported in dialysis patients, but incidence and risk factors of such complications in chronic renal failure (CRF) predialysis patients are debated.

METHODS

We prospectively assessed the incidence of first myocardial and cerebral infarction episodes in a cohort of 147 CRF patients (99 male) followed from January 1985 to December 1994. Relevant clinical and laboratory risk factors for atherogenesis were determined at yearly intervals. They included blood pressure, smoking, blood lipids, fibrinogen, and homocysteine which were compared in patients with (CVA+) or without (CVA-) occurrence of cardiovascular (CV) atherosclerotic accidents.

RESULTS

Incidence of CV accidents was nearly three times higher in CRF patients than in the French general population in both genders. In particular, incidence of myocardial infarction in male patients aged 45-55, 55-65 and > 65 years was 7.6, 18.2, and 27.8/1000 patient-years, respectively, compared to 3.4, 8.9, and 10.4/1000 subject-years in the general population. Although age and degree of renal failure at onset of CV events or at end of follow-up did not differ between CVA+ and CVA- groups, cigarette smoking (24.5 [SD 24.3] vs 8.2 [14.7] pack-years, P < 0.0001) and systolic blood pressure (159 [19] vs 148 [19] mmHg, P < 0.001) were markedly higher in CVA+ patients. Similarly, mean plasma HDL-cholesterol was lower, whereas LDL-cholesterol, triglycerides, apoB, Lp(a), fibrinogen, and homocysteine levels all were significantly higher in CVA+ than in CVA- patients. Multivariate Cox analysis identified cigarette smoking, systolic pressure, HDL cholesterol, and fibrinogen as independent risk factors for developing CV accidents.

CONCLUSIONS

Incidence of atherosclerotic CV complications is abnormally high in predialysis CRF patients, suggesting that the uraemic state per se is associated with atherogenesis. As several of the identified clinical and metabolic risk factors for such accidents are potentially remediable by specific therapeutic interventions, prophylactic measures should be initiated long before start of renal replacement therapy.

[Benefits of early nephrological management in chronic renal failure]

OBJECTIVES

We evaluated whether early nephrological referral of patients with chronic renal failure (CRF) resulted in improved condition of patients at initiation of maintenance dialysis and in better outcome on dialysis.

PATIENTS AND METHODS

We prospectively recorded clinical status, laboratory parameters, length of hospital stay and outcome of 900 CRF patients who started maintenance dialysis at Necker hospital between January 1989 and December 1996. We compared patients who benefited regular nephrological follow-up, and patients who were referred in emergency conditions at the ultimate stage of CRF.

RESULTS

Among the 900 patients, 731 (81.2%) had regular nephrological follow-up, including 632 (70.2%, group IA) with optimal preparation to dialysis and 99 (11%, group IB) whose clinical course was complicated due to heavy comorbidity, whereas 169 (18.8%, group II) had no previous nephrological management. Over the 8-year observation period, the proportion of the latter group did not decrease. Late referred patients had higher blood pressure level, more frequent fluid overload, higher serum levels of urea, creatinine, uric acid and phosphate, and lower levels of bicarbonate, calcium, albumin and creatinine clearance that did well-prepared patients. Mean (+/- SD) hospital stay was 29.7 +/- 15.8 days in the former compared to only 4.8 +/- 3.3 days (p < 0.001) in the latter. Early deaths within 3 months of dialysis initiation were more frequent (7.1 vs 1.6%, p < 0.05) and less patients subsequently were able to be treated out-center (20.1 vs 40.7%, p < 0.05) in group II than in group IA. The overcost induced by late referral may be estimated at 0.25 million French francs per patient.

CONCLUSION

An unjustified late nephrological referral of CRF patients still is observed in nearly 20% of cases. Such late referral is detrimental to both patients in terms of altered quality of life and long hospital stay, and to the collectivity due to heavy overcost. Closer cooperation between family physicians and nephrologists is needed to provide optimal management and allow timely preparation to maintenance dialysis of CRF patients.

Continuous venovenous haemodiafiltration in the acute phase of neonatal maple syrup urine disease

Maple syrup urine disease results in accumulation of leucine and its metabolites, which may lead in the long term to neurological dysfunction. In acute neonatal crises, large amounts of leucine may be removed by continuous venovenous haemofiltration. This extracorporeal technique has its risks and hazards, which increase with duration of treatment. We report three neonates in life-threatening conditions due to maple syrup urine disease, treated for not more than 12 h with various continuous venovenous techniques: continuous haemofiltration, haemodiafiltration and haemodialysis. The efficiency of and tolerance to these techniques was evaluated. For all three patients, plasma leucine levels decreased dramatically from 2186, 3818 and 2536 mumol/L to 1131, 1275 and 488 mumol/L, respectively. Leucine clearance obtained was 4.28 ml/min in haemodiafiltration. Their patients' neurological status improved rapidly and they have a normal developmental quotient at 22 months, 13 months, and 11 months of age, respectively. Tolerance was good except for hypothermia and drop in haematocrit in all cases. Haemodiafiltration management was more cumbersome and time consuming because it required continual adjustment of the substitution fluid flow rate to precisely balance inflow and outflow rates. We recommend continuous venovenous haemodialysis as the therapy of choice. It might be anticipated that improvement of this technique, by increasing dialysate flow rate and blood flow rate, will allow leucine concentration to be decreased below 1000 mumol/L within 6-8 h, whatever the initial level.

Blood density monitoring during dialysis

Continuous monitoring of blood density (BD) was preformed in 4 stable dialysis patients in 20 sessions using a density meter based on a mechanical oscillator technique. Mean predialysis and postdialysis BDs were 1.0427 +/- 0.0031 g/cm3 and 1.0502 +/- 0.0055 g/cm3, respectively. For similar predialysis to postdialysis total body water reduction, significant difference in the mean BD increase was found between hypotensive and nonhypotensive groups (1.29 +/- 0.07%, 0.47 +/- 0.12%, respectively; p < 0.001). Eight hypotensive episodes occurred during 6 sessions. The mean value of the blood density changes slope (dBD/dr) during the 5 min preceding a hypotensive episode increased about 2.5 times more than did the mean of the predialysis to postdialysis blood density slope (27.6 +/- 2.2 g/cm3.min.10(-5), 10.5 +/- 0.4 g/cm3.min.10(-5), respectively; p < 0.001) under the condition of a constant ultrafiltration rate of 18.9 +/- 0.6 ml/min. Continuous monitoring of blood density allows abrupt change in plasma volume to be identified and seems to have a potential utility to the prevention of symptomatic hypotension episodes in patients receiving hemodialysis.

Age and gender-related incidence of chronic renal failure in a French urban area: a prospective epidemiologic study

OBJECTIVE

To determine the age- and gender-related incidence of chronic renal failure in a French urban area.

METHODS

Prospective study of adult patients newly identified as having established, chronic renal failure defined by serum creatinine (Scr) > or = 200 mumol/l, with the cooperation of all nephrology and dialysis units in the Ile de France district (10,660,000 inhabitants) during a 1-year period.

RESULTS

2775 patients (1780 males, 995 females) were referred with Scr > or = 200 mumol/l between July 1991 and June 1992, an overall incidence of 260/million population. 847 had advanced renal failure (Scr > or = 500 mumol/l) and 541 patients (19.5%) were > or = 75 years of age. The age-related incidence was 92, 264, 523 and 619/million population in the age groups 20-39, 40-59, 60-74 and > or = 75 years old, respectively. The annual incidence was twice as high in males than in females up to 75 years and three times as high in patients > or = 75 years (1124 vs 356/million population). Based on the proportion of patients reaching end-stage renal failure within one year of referral, the minimal estimation of the need for supportive therapy is 81/million/year.

CONCLUSIONS

This epidemiological study in a large French urban area indicates an incidence of 260 patients per million population annually referred to nephrology units for chronic renal failure defined by Scr > or = 200 mumol/l, with a marked preponderance of males and a dramatic increase of incidence with age in both genders.

[Demography and effects of chronic renal insufficiency in Ile-de-France]

In order to assess the incidence of chronic renal failure (CRF) and the demographic characteristics of affected patients, a prospective, multicenter epidemiologic study was conducted with the cooperation of all nephrology and dialysis units in the Ile-de-France district, the total population of which is 10660000 inhabitants (source: national census, march 1990). Included were patients with a plasma creatinine (Pcr) concentration > or = 200 mumol/l referred during the one-year period from July 1, 1991 until June 30, 1992. The overall response rate was 98.5%. A total of 2775 adult patients were recorded, including 1780 males (64%) with a mean (+/- SD) age of 58.1 +/- 16.3 years and a mean Pcr of 447 +/- 214 mumol/l, and 995 females (36%) with a mean age of 59.2 +/- 16.4 years and a mean Pcr of 425 +/- 185 mumol/l. Age of patients was < 40 in 16%, 40-59 in 31%, 60-74 in 34% and > or = 75 years in 19%. Pcr was 200-399 mumol/l in 54%, 400-599 mumol/l in 25%, 600-799 mumol/l in 12% and > or = 800 mumol/l in 9%. The overall incidence of CRF was 260/million population/year, twice higher in males than in females (348 vs 179/10(6)/year, p < 0.001). Incidence of CRF dramatically rose with age in both genders, with figures as high as 1124 and 356/10(6)/year respectively in male and female patients aged > or = 75 years, vs 288 and 151/10(6)/year in patients aged < 40 years. A sequential evaluation was performed in a representative sample of 251 patients with initial Pcr > or = 300 mumol/l. End-stage renal failure (ESRF) was reached within one year in 99% of patients with PCr > 600, 49% with Pcr 500-599, 24% with PCr 400-499 and 11% with PCr 300-399 mumol/l. Based on these figures, the predicted incidence of ESRF within one year of referral was 864 out of the 2775 patients, an estimated annual incidence of 81 patients per million population. In conclusion, this prospective study affords the first direct information on the incidence of chronic renal failure and the demographic characteristics of patients with CRF in the Ile-de-France district. Due to the design of the study conducted only in nephrology units, the estimated figure of 81 new patients per million population per year reaching ESRF is a minimal evaluation. In view of the relentless aging of population in France, an incidence of at least 100 ESRF patients per million population per year is to be expected in the next future.

Accumulation of 5 alpha-reduced androgen glucosiduronates associated with impaired removal in young male hemodialysis patients

Hypothalamic-pituitary gonadal function is commonly altered in dialysis patients. Even though an improvement in general status and well-being has been noted after recombinant human erythropoietin supplementation, no significant changes were observed in the sex hormone profile. Pituitary gonadal axis as well as 5 alpha-reduced androgen glucosiduronates (i.e. 5 alpha-androstane,3 alpha,17 beta-diol and androsterone) profiles were studied in 23 young male stable dialyzed patients and compared to an age-matched group of healthy subjects. 5 alpha-Reduced androgen glucosiduronates are products of peripheral testosterone (T) metabolism and seem to be a useful tool in assessment of the male androgen status. Their polarity facilitates their urinary excretion, and their clearance is similar to the glomerular filtration rate in healthy men. We observed 1) a pituitary-Leydig cell dysfunction supported by normal serum estradiol and T levels, low free T, and increased LH levels; 2) an alteration of the dehydroepiandrosterone (DHEA) sulfate-DHEA interconversion, reflected by a dramatic decrease in DHEA while DHEA sulfate levels remained in the normal range; 3) an accumulation of 5 alpha-reduced androgen glucosiduronates, whose removal was impaired as shown by their very low sieving coefficients (< 0.012). Taken together, the above observations are consistent with alteration of spermatogenesis with respect to dialysis duration in which earlier elevated baseline serum LH levels indicate a primary defect in Leydig cell function.

Factors influencing progression of renal failure in autosomal dominant polycystic kidney disease

Autosomal dominant polycystic kidney disease (ADPKD) frequently leads to end-stage renal failure (ESRF) in the sixth decade of life, but considerable heterogeneity exists in the rate of progression of renal failure. The respective contribution of genetic factors and of potentially amendable factors, such as blood pressure control or protein intake limitation, on the rate of progression in ADPKD patients is still debated. To evaluate the role of factors influencing the rate of progression of renal failure in ADPKD, we retrospectively analyzed the annual rate of decline of creatinine clearance (Ccr) in 109 ADPKD patients followed from the time a Ccr value of 30 to 50 mL per min/1.73 m2 was measured until ESRD and need for hemodialysis (Study A), and in 48 undialyzed ADPKD patients followed for at least 4 yr from the time a Ccr value of 50 to 60 mL per min/1.73 m2 was measured (Study B). In Study A, the decline in Ccr (delta Ccr) (mean +/- SE) was 5.8 +/- 0.2 mL per min/1.73 m2 per year in the whole series, and was lower in females than in males (5.0 +/- 0.2 versus 6.4 +/- 0.2, P < 0.001). Accordingly, ESRF was reached at a later age in female patients (55.1 +/- 1.2 versus 50.6 +/- 1.2 yr, P < 0.01). The age at ESRF in male patients was lower when the disease was transmitted by mother than by father (46.3 +/- 1.9 versus 54.1 +/- 1.8 yr, P < 0.01), whereas no significant effect of the gender of the affected parent was apparent in female patients. By regression analysis, there was a positive but weak relationship between delta Ccr and mean arterial pressure (average value during follow-up, 107 +/- 1 mm Hg, r = 0.224, P < 0.05) but not with dietary protein intake (mean value in follow-up, 0.87 +/- 0.03 g/kg per day, r = 0.10, P = 0.33) nor with proteinuria at baseline, which was lower than 0.3 g/day in 104 cases (r = 0.10, P = 0.28). There was a negative relationship between age at ESRF and delta Ccr (r = 0.245, P < 0.05), with a later and slower progression in older subjects. In Study B, the mean decline in renal function during follow-up was 5.3 +/- 0.4 mL/min/1.73 m2 per year, a value close to that observed in Study A. By multiple regression analysis of the overall population (studies A and B combined), only MAP, age and gender were independent predictive factors of delta Ccr but all studied parameters taken together accounted for at best 20% of delta Ccr variation. We conclude that the rate of progression of renal failure in ADPKD patients is mainly determined by gene expression, with female gender and older age associated with a slower progression, whereas blood pressure control, but not protein intake, exerts a limited beneficial influence on the rate of progression in patients with advanced polycystic kidney disease who already have significant renal insufficiency.

[The Carboclip, a new, atraumatic vascular access for hemodialysis]

The Carboclip is a no-needle vascular access device made of an inverted Titanium body. The horizontal bar of 6 mm inner diameter is connected with artery and vein via a vascular graft. The vertical body houses an elastic plug in which is inserted a double canula diving in the blood stream for extracorporeal blood circulation (EBC). The body is wrapped by a flange made of microporous biocarbon in which the subcutaneous fibroblast will growth, forming an antimicrobial barrier and fixing the port to the skin. We report our experience on 30 devices implanted in 30 sheep with 26 extracorporeal circulation simulating hemodialysis. The results demonstrate good tightness of the plug as well at rest as during EBC procedure, sufficient blood flow rate of about 400 ml/min, and benefits of the microporous carbon flange.

Urea rebound and residual renal function in the calculation of Kt/V and protein catabolic rate

Kt/V-urea and protein catabolic rate (PCR) are used for dialysis prescription and evaluation of protein intake of patients on regular dialysis treatment. The study was undertaken to determine the implication of urea rebound and residual renal function (RRF) on the calculation of Kt/V-urea and PCR for 61 patients. Kt/V-urea and PCR were calculated, implementing or not urea rebound at one hour after the end of dialysis session. Urea and creatinine rebound rate in patients without RRF was significantly higher than in patients with RRF (P < 0.05). In patients without RRF, creatinine generation rate and Kt/V-urea calculated without rebound were significantly higher than calculated with rebound (P < 0.001). On the contrary, calculation of urea generation and PCR is not affected by these parameters. It is concluded that: (1) Rebound rate magnitude of urea and creatinine is dependent on solute molecular weight, RRF and probably on dialysis duration, whereas rebound rate magnitude of phosphorus is not affected, and (2) Rebound should be taken into account in the calculation of Kt/V-urea and creatinine generation rate in patients without RRF, otherwise, they would be overestimated.

Kinetics of technetium-labeled heparin in hemodialyzed patients

Technetium-labeled heparin kinetics studies were undertaken in 12 hemodialyzed patients, where heparin was used over a long term (1 to 10 years) for anticoagulation of the extracorporeal circuit. The 99mTc-heparin (99mTc VECTOSCINT, Solabco Nuclear, Coutras, France) used has a 10 mCi activity and a labeling efficiency of more than 95%. Two healthy subjects served as control. After an i.v. bolus of 2 ml 99mTc-heparin, corresponding to 170 +/- 10 IU, radioactivity of kidney, liver, knee and shoulder was recorded with a gamma camera at t1-h, t3-h and t6-h during 120, 152 and 215 s, respectively. Radioactivity recorded was computerized, giving quantitative data for comparison. In hemodialyzed patients, accumulation of radioactivity (mean +/- SEM 10(6) x activity count) was significantly higher at the knee (11.3 +/- 1.1 vs. 4.9 +/- 0.4; p < 0.05; 13.4 +/- 1.1 vs. 5.7 +/- 0.7; < 0.02; and 14.7 +/- 0.8 vs. 5.3 +/- 0.6; < 0.001), and on the shoulder (17.3 +/- 1.1 vs. 10.7 +/- 1.4; p < 0.05; 19.9 +/- 1.0 vs. 10.9 +/- 1.7; < 0.01; 20.8 +/- 1.1 vs. 10.1 +/- 0.9; < 0.01) at t1-h, t3-h and t6-h, respectively, than in control subjects at the same areas. Although direct evidence is not in hand, accumulation of heparin in bone tissue due to renal excretion failure could play a role in mineral metabolism resulting in osteopenia in hemodialyzed patients.

Detrimental effects of late referral in patients with chronic renal failure: a case-control study

Despite broader indications and easier access to renal replacement therapy during the past decades in Western countries, an unduly high number of patients is still referred to maintenance hemodialysis (HD) at a very advanced stage of chronic renal failure (CRF). To assess whether such late referral induces detrimental effects, we retrospectively compared clinical status and laboratory features in 20 patients who had been referred to us less than one month prior to first HD (late referral, or LR group) and in 20 sex- and age-matched controls who had undergone regular follow-up for at least six months prior to HD (early referral, or ER group). Male to female ratio was 12/8 and age averaged 53.5 years in both groups. Mean (+/- 1 SD) systolic and diastolic blood pressure were higher in LR group than in controls (180 +/- 14/102 +/- 10 vs. 153 +/- 15/86 +/- 7 mm Hg, P < 0.001) and fluid overload with pulmonary edema was present in 13/20 versus 3/20 patients (P < 0.001). Plasma concentrations (mmol/liter) of creatinine (1.12 +/- 0.27 vs 0.97 +/- 0.11, P < 0.01) and phosphate (2.58 +/- 0.47 vs. 1.92 +/- 0.31, P < 0.001) were higher, whereas plasma levels of bicarbonate (14.2 +/- 3.9 vs 22.5 +/- 4.2, P < 0.001) and calcium (1.85 +/- 0.24 vs. 2.27 +/- 0.15, P < 0.001) were lower in LR than in ER group, as were hemoglobin (7.1 +/- 1.1 vs. 9.4 +/- 0.9 g/dl, P < 0.001) and serum albumin levels (35.3 +/- 4.8 vs. 39.7 +/- 3.4, P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Lipid peroxidation abnormalities in hemodialyzed patients

In order to test the existence of a possible oxidative damage during hemodialysis, plasma conjugated dienes (CD), plasma and red blood cell (RBC) thiobarbituric acid (TBA) reactants were investigated in 25 patients receiving regular dialysis treatment (RDT). The RBC TBA reactant concentration was significantly increased in RDT patients in comparison with healthy subjects. The extracellular antioxidant systems were evaluated by the assay of plasma antioxidant activity, plasma tocopherol, urate, transferrin, haptoglobin and ceruloplasmin levels. Except urate and transferrin, none of these parameters were different between the two groups. On the other hand, in RDT patients, RBC superoxide dismutase (SOD) and glutathione peroxidase (GPX) activities were significantly lower than in healthy subjects. There was an inverse correlation between decreased RBC GPX and RBC TBA reactant concentration. These results show in RDT patients the existence of an oxidizing stress, mainly intracellular, which could be due, in part, to a decrease in SOD and GPX activities.

The most suitable calculation of Kt/V-urea: Kt/V = ln(Ci/Cf)

Although various simplified calculation formulae of Kt/V-urea based on urea kinetic modeling have been reported, all the formulae include errors such as post-dialysis urea rebound and urea generation during a dialysis session. In the present study, in order to calculate the precise Kt/V-urea, a formula of Kt/V-urea, taking into account post-dialysis plasma urea rebound and urea generation during a dialysis session (Kt/V-P) was proposed, and compared to other formulae already published, in 49 dialysis patients without residual renal function (26 M and 23 F; mean age, 65 +/- 2 years; mean dialysis duration, 70 +/- 7 mos). The precise post-dialysis plasma urea concentration was significantly higher than the actually measured post-dialysis plasma urea concentration by approximately 12%, and Kt/V-P corresponded to Kt/V-urea = ln(Ci/Cf) with the best correlation in the formulae utilized in the present study, around 1 of Kt/V-urea, which is clinically the most important range. It is concluded that Kt/V-urea = ln(Ci/Cf) is the most suitable formula for the calculation of Kt/V-urea, when post-dialysis plasma urea rebound and urea generation during a dialysis session are taken into account.

Evaluation of parameters for adequate dialysis therapy: (2). Comparison between parameters according to UKM and other laboratory data

Urea kinetic modeling (UKM) is often regarded as the best method for assessing the dialysis adequacy and consequently for the prescription of treatment time. However, other parameters are involved in the monitoring of end stage renal disease (ESRD) patients. Kt/V-urea and protein catabolic rate (pcr) were evaluated in 53 ESRD patients (25 males and 28 females; mean age, 60 +/- 2 years old; mean duration, 80 +/- 11 months), twice at an interval of 4 months, and pre-dialysis concentration of (pre-DC) plasma potassium, bicarbonate, calcium and phosphate were measured. The pre-dialysis systolic blood pressure and hematocrit were also recorded. The numbers of patients who were within the optimal range of Kt/V-urea and pcr recommended by Gotch and Sargent were 36 (67.9%) and 39 (73.6%), respectively, at the first control period, and 39 (73.6%) and 44 (83.0%) at the second control period. However, only about 50% of the patients were within the optimal range of pre-DC plasma calcium, phosphate and bicarbonate. Furthermore, very few patients fulfilled the conditions for all the parameters. It is concluded that (1) UKM is required to describe the domain of dialysis prescription, and (2) other parameters which are not dependent so much on dialysis should be taken into account for assessing the adequacy of dialysis.

Initiation of dialysis: when?

Initiation of dialysis depends upon several parameters including medical and non-medical reasons. Among the medical parameters measured or calculated creatinine clearance from plasma creatinine concentration seems to be the most reliable factor although clinical parameters such as gastro-intestinal disorders, cardiovascular, hematological, neurological manifestations and last but not least general status of the patient tend to play a determinant role in the decision of initiating dialysis. Dialysis is usually initiated for patients with a normalized creatinine clearance of 5 ml/min.1.73 m2 but optional dialysis could be initiated from a normalized creatinine clearance of 10 ml/min.1.73 m2, in case the capability of the patient and the physician to tolerate the burden of uremic syndrome is overcome. Rather than employing dialysis too late, it now seems advisable to initiate dialysis earlier in the course of chronic renal failure. Actually, retrospective analysis of 167 over 625 cases records from 1981 to 1985 and of 178 over 700 case records from 1986 to 1990 in the Department of Nephrology, Necker Hospîtal, plasma creatinine concentration at initiation of dialysis of the two period was 1044 +/- 17 and 981 +/- 13 mol/L respectively, corresponding to a creatinine clearance of 6 and 7 ml/min. It is clear now that management of chronic renal failure patients should be considered as a whole and initiation of dialysis is the end point of this global strategy. Definitely, optimal time for initiating dialysis should take into account various parameters, both biological and clinical as well as associated parameters such as age of the patient and involved systemic disease.

The estimation of whole blood viscosity by a porous bed method

A significant impediment in determining the relative contribution of whole blood viscosity to the pathogenesis of cardiovascular and cerebrovascular disease has been the lack of an uncomplicated method to measure whole blood viscosity. To address this problem, a simplified porous bed viscometer has been developed to measure whole blood viscosity. Whole blood is passed through a porous bed of branching channels with a mean pore diameter of 69.6 +/- 20.2 microns and an estimated mean shear rate of 19.6 seconds-1. The effects of sample collection, sample storage, and temperature are described. The mean whole blood viscosity of 242 healthy persons was 22.7 +/- 5.3 seconds, which, when corrected to centipoise using Darcy's equation, corresponds to an apparent viscosity of 5.7 +/- 1.3 cp. There was a significant difference in the whole blood viscosity of normal men and women related to their different packed cell volumes. Platelets and granulocytes influenced whole blood viscosity in proportion to their contribution to the total packed cell volume. Fibrinogen levels did not significantly influence measured whole blood viscosity, which is consistent with the disaggregating conditions and the mean shear rate of the instrument. The porous bed viscometer is a convenient means to measure whole blood viscosity and it should be useful as a screening test for clinical and epidemiologic studies.

[The future of hemodialysis in the adult]

By the year 2000, the perspectives for hemodialysis performed in adults will be oriented towards facilitation of the practice of hemodialysis as a better control of clinical symptoms observed in end stage renal failure treated by hemodialysis. Blood access is the main problem which remains to be solved. The authors describe the advantages and disadvantages of the methods presently used and give the "state of the art" of "blood access" prosthesis. Almost all symptoms encountered in renal failure patients treated by hemodialysis can be efficiently treated. Hypotensive drugs usually reduce hypertension which resists adequate treatment by hemodialysis. Most of the symptoms of osteodystrophy can be avoided by adequate diet associated with the prescription of vitamin D analogs. Nevertheless, the prolongation of hemodialysis treatment duration over 7 years has led to the apparition of destructive arthropathies which are very painful and handicapping. They are related to amyloid deposit of beta 2-microglobulins. Progress in hemodialysis technics and a better control of uremic symptoms allow application of this treatment at all ages of life. The authors examine specific problems concerning school-aged teenagers and aged persons. They show that results already achieved allow a daily treatment of these patients. This is a first step for the generalisation of this procedure to all patients and its advantages are described. Improvement of hemodialysis technics for the year 2000, as can be expected, mainly depends upon progress in knowledge of biocompatibility parameters between materials used in the artificial kidney and patients tissues, mainly blood vessels.

Phosphate removal during hemodialysis, hemodiafiltration, and hemofiltration. A reappraisal

Kinetics of phosphate removal, based on hourly collection of used dialysate or filtrate and hourly changes of phosphate plasma concentration, were studied in hemodialysis (QB 300; QD 500 ml/min), hemodiafiltration (QB 300; QD 500; QSF 25 ml/min), and hemofiltration (QB 250; QSF 70 ml/min) for six 5-hour sessions in each mode of therapy. Whatever the pretreatment phosphate concentration (1.5-2.0 mmol/L range), and whatever the treatment modality used, final plasma phosphate concentration was in the narrow range of 0.8-0.9 mmol/L, and about 50% of the total mass transfer occurred during the first 2 hours. At the third hour, a steady state is reached, suggesting that removal of phosphate is limited by the rate of phosphate transfer from body compartments to extracellular fluid, which was on the average about 362 mumol/kg.hr. Consequently, total phosphate mass transfer accounts only for 20 to 28 mmol per session. Control of pretreatment phosphatemia in the range of 1.5 to 2.0 mmol/L depends on daily phosphate binder prescription, calcitriol supplementation, and control of metabolic acidosis; one cannot rely on intermittent phosphate removal during the dialysis session.

[Characteristics of artificial membranes]

The artificial membranes used in haemodialysis and haemofiltration are either cellulosic or made of synthetic polymers, such as polyacrylonitrile, polysulfone, polycarbonate, polymethylmetacrylate and ethyvinylalcohol. During dialysis the water and solute transfer primarily depends on hydraulic permeability and sieving coefficients. At present, high-flux membranes have sieving coefficients for urea (Mol. wt 60) to inulin (Mol. wt 5,200) that are similar to those of the glomerular basal lamina, whereas their hydraulic permeability remains well below that of the renal filter. Bioincompatibility factors responsible for acute, anaphylactoid-like reactions and chronic inflammatory complications have been identified. The choice of the correct dialysis membrane must rest not only on performance criteria but also on biocompatibility and economic criteria.

Phosphate kinetics in acetate-free biofiltration

The phosphate kinetics during bicarbonate dialysis (BCD) and Acetate-free Biofiltration (AFB) were determined in 3 stable regular dialysis patients. These patients were switched to a 6-month period of AFB after a 12-month period of BCD. The plasma levels of phosphate, urea, and bicarbonate, and mass removal of phosphate and urea were measured every hour, during 3 consecutive dialysis sessions on BCD and AFB. The plasma phosphate behavior revealed a peculiar form with two main components, which differed from that of urea. The plasma phosphate level fell sharply during the first 2 hours of treatment, and then remained at a plateau towards to the end of the session. The plasma bicarbonate levels during the treatment sessions in the case of AFB were significantly higher than that in BCD. The actual mass removal in AFB was similar to that BCD, despite a significantly lower value of pre-plasma phosphate. A high ultrafiltration rate and better control of acidosis might be the reason for the better performance of phosphate mass removal in AFB. Better control of phosphatemia due to AFB can lead to a reduction in the amount of phosphate binders which have several untoward side effects.

Influence of uremia on polymorphonuclear leukocytes oxidative metabolism in end-stage renal disease and dialyzed patients

The oxygen (O2) consumption, and superoxide anion (O2-.) and hydrogen peroxide (H2O2) production by polymorphonuclear leukocytes (PMNs) were investigated in 5 end-stage renal disease patients, before and after the 1st, 4th and 10th dialysis sessions. Resting values of O2-. production and O2 consumption were not significantly different from values for PMNs from normal subjects. After stimulation by opsonized zymosan or phorbol myristate acetate, the three parameters measured were significantly (p less than 0.001) enhanced in comparison with healthy control values. Cross-incubation studies showed a lack of effect of patient plasma on O2-. production by stimulated control cells: PMN oxidative metabolism would therefore appear to be increased in these patients. The anomalies observed probably arise via a mechanism involving a cellular dysfunction resulting from the renal disease, rather than from the presence of a plasma factor.

[The clinical value of correction of acidosis by acetate-free biofiltration in patients on regular dialysis treatment]

Effects of metabolic acidosis were compared between bicarbonate dialysis (BCD) and acetate-free biofiltration (AFB). Three stable dialysis patients (1M, 2F, mean age 30 yrs) were selected for the study because their bicarbonate (BC) pre-dialysis plasma concentration were always under 16 mmol/l while they were on 33 mmol/l-BCD thrice weekly for 12 months. They were switched to a 6 months period of AFB. Pre- and post-dialysis BC plasma concentration, other blood chemical parameters and mass removal (total collection of used dialysate) of urea (U), creatinine (Cr), uric acid (UA), and phosphate (P) were measured during the last week of each period, including 3 dialysis sessions. Mean calorie and protein intake were 29.4 KCal/kg.d and 1.5 g/Kg.d (BCD period) and 38.2 Kcal/Kg.d and 1.5 g/Kg.d (AFB period) respectively. BC plasma concentration (Mean +/- SE, mmol/l) at the pre and post-dialysis in AFB were significantly higher than those in BCD (16.6 +/- 0.7 vs 20.8 +/- 0.6; p less than 0.001, 22.7 +/- 0.8 vs 25.8 +/- 0.8; P less than 0.02). Pre- and post-dialysis U plasma concentration (Mean +/- SE, mmol/l) in AFB were significantly lower than those in BCD (34.3 +/- 2.51 vs 20.8 +/- 0.59, 10.5 +/- 1.32 vs 7.5 +/- 0.92; P less than 0.001). Pre-dialysis P plasma concentration (Mean +/- SE, mmol/l) in AFB was significantly lower than that in BCD (1.85 +/- 0.09 vs 1.50 +/- 0.15; P less than 0.01). Cr, UA and P mass removal in BCD and AFB were not significantly different. However, U mass removal in AFB was significantly lower than that in BCD.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation of plasma sodium concentration during hemodialysis by computerization of dialysate conductivity

Kinetics modeling based on sodium mass balance and changes in conductivity at the dialysate outlet compared to that at the dialysate inlet, led to predicting the plasma water conductivity of the blood inlet. Conductivity transducers, with temperature compensation, located at the dialysate inlet and outlet ports of the dialyzer and connected to a conductimeter, were interfaced with a portable computer for data acquisition. In 38 dialysis sessions, a close relationship was found between estimated plasma water conductivity (CdBi) and measured plasma sodium concentration [Na]Bi, according to the formula: CdBi = 0.101[Na]Bi + 0.37 (n = 38; r = 0.922). The study shows that plasma sodium concentration at the dialyzer inlet could be evaluated, with a standard error of +/- 1.5 mEq/L, by continuous measurement of conductivity gradient between dialysate inlet and outlet.