Analysis of the optical concentration curve to detect access recirculation.

The optical blood volume curve sometimes presents either a positive or a negative rapid and reversible variation (spike) during the step of the dialysate conductivity, automatically set by the monitor for the ionic dialysance (ID) measurement. We studied whether this feature was in relation with access recirculation. Firstly, we studied if the manoeuvre of reversed position of the blood lines created the same feature in the blood volume curve. Secondly, two medical teams systematically checked for the presence of spikes and measured the access recirculation by way of an ultrasound dilution technique. The manoeuvre of reversed position of the blood lines invariably reproduced the same feature on the curve of the optical blood volume measurement in case of a recirculation greater than 20%. In the normal position of the blood lines, the 16 patients with an access recirculation greater than 20% had spikes. Spikes during ID measurement were not constant for an access recirculation between 10 and 20% and did not occur for an access recirculation of less than 10% or an undetectable one. The special spike of the optical blood volume curve occurring during the ID measurement clearly detects access recirculation. The specificity is of 100% when this modification is present all along the dialysis session for all the ID measurements and the sensitivity is 100% when the access recirculation is greater than 20%.

[Ionic dialysance and quality control in hemodialysis]. / Dialysance ionique et contrôle de qualité de l'épuration en hémodialyse.

Quantification of dialysis is based on the measurement of effective urea clearance (K), dialysis dose (Kt) or normalized dialysis dose (Kt/V). During the last 20 years, Kt/V was the single parameter actually useful for quantifying dialysis efficiency, because it can be calculated from just blood or dialysate urea concentrations at the beginning and at the end of the dialysis session. However the calculation of the normalized dialysis dose (Kt/V) actually delivered to the patient cannot be performed during each dialysis session, because of the need of urea concentration measurements. Ionic dialysance is a new parameter easily measured on-line, non-invasively, automatically and without any cost during each dialysis session by a conductivity method. Because ionic dialysance has been proved equal to the effective urea clearance taking into account cardiopulmonary and access recirculation, it is becoming an actual quality-assurance parameter of the dialysis efficiency.

[Performance of central catheters on the filtration yield measured by ionic dialysance ]. / Performances des cathéters centraux sur les débits d'épuration mesurés par la dialysance ionique.

Certain number of dysfunctions, particularly decline of blood flow or, recirculation, can decrease the adequacy of depuration, when central catheters are used. Ionic dialysance is available on some monitors (Integra), and reflects perfectly the effective urea clearance, permits to watch any variation in the effective clearance of the depuration system due to these dysfunctions. We report on our experience in a retrospective study from 01/01/2000 to 30/11/2000 where we compared the effective clearance of depuration measured by the ionic dialysance of all the sessions of dialysis made on central catheters in our center, with the forecast clearance of sessions made in the same conditions of dialysis but with a non pathologic fistula. The mean of dialysances decreases of 12% on Dual Cath, of 15% on Ash Split Cath, and 28% on Silicone single lumen femoral catheter, and further analysis makes appear that respectively 60, 65 and 92% of these sessions have a mean of dialysance--10% with regard to the threshold value. The recirculation is certainly the major factor of this decline of the ionic dialysance as well as the decline of blood flow due to partial clotting or relative low venous central pressure due to hypovolaemia. Our data incite to more vigilance for a possible sub dialysis during the use of the central catheters, and prove the utility of the ionic dialysance to watch the technical conditions of the session of dialysis.

[Factors determining the choice of a modality of treatment by dialysis: a study of nine dialysis centers]. / Facteurs déterminant le choix d'une modalité de traitement par dialyse: une enquête dans neuf centres de dialyse.

BACKGROUND: The objective of this cross-sectional study in a population of 1472 dialysis patients was to identify the main factors involved in the choice of a specific option for dialysis therapy, taking into account three different types of criteria such as medical dependence (DM), nurse care requirement (SI) and independence for dialysis therapy (CA). METHODS: Each patient has been analysed, independently of present treatment modality, according to the above three criteria, namely DM, SI and CA. For each type of parameter, patients have been allocated to one of three levels, each level being established to evaluate whether dialytic treatment should be undertaken as hospital centre dialysis (HDC) or in a facility off the hospital. Level 3 of any one category corresponded to the inability of doing haemodialysis at home (HHD) or in self-care unit (AD). Level 2 included patients who could be treated in AD or by peritoneal dialysis (PD) with the assistance of a nurse. CAPD or HHD were considered as potential treatment modalities only in patients qualifying for level 1 of each criterion. RESULTS: In the patient population as a whole, the following treatment options were observed: HHD 3.6%, CAPD 6%, PD 1.8%, AD 16.3% and HDC 72.2%. For medical dependence (DM) there was a relatively even distribution for the three levels in six centres. In contrast, two centres were characterized by a predominance of DM level 3. Differences in DM levels between centres were greatly reduced when considering separately only those patients who were actually treated by CAPD, HDC and AD. SI levels were more uniformly distributed within all centres, and this was true for HCD and AD patients. When considering CA levels in HDC patients, a large predominance of CA level 3 was observed in all centres whereas CA level 1 was nearly in existent. CONCLUSION: The major finding of this study was that the inability or the refusal of dialysis patients to participate at treatment, independently of medical condition and nurse care requirement, was the main factor in the choice of hospital centre dialysis.

[Epidemiology of primary glomerulonephritis in Picardie]. / Epidémiologie des glomérulopathies primitives en Picardie.

Between 1 January 1976 and 31 December 1986, primary glomerulonephritis was histologically diagnosed in 319 patients, living in a region of 675,000 inhabitants at the time of renal biopsy. The prevalence of primary glomerulopathy was 0.4/1000 inhabitants. The annual incidence was determined during two 5 year periods: period A (1976-1980) and period B (1981-1985): they were, respectively, 3.4 and 4.5 for 100,000 inhabitants. Berger's focal glomerulonephritis was the most common (30 p. 100) and its incidence was increasing. In contrast, membranoproliferative and acute glomerulonephritides were sharply decreased (almost disappeared), while membranous glomerulonephropathies and glomerulopathies with minimal glomerular lesions or proliferative forms with crescents increased. All primary glomerulonephritides were more prevalent in men and their frequencies increased with age. Our findings lead to the following conclusions: a) the low prevalence and incidence of primary glomerulopathies (3 times less than in other published studies) probably reflect the under medicalization of our region and the attractiveness of neighbouring metropolis, rather than a real decrease in the disease; b) the quasi- disappearance of acute and membranoproliferative glomerulonephropathies and the high incidence of IgA glomerulonephropathies suggest that their pathogenetic associations with infections sensitive to antibiotics are different; c) the increased frequency of membranous glomerulonephropathy and the glomerulopathy with minimal glomerular lesions in aged subjects is most likely due to their polymedication.

Hemodialysis in the treatment of lactic acidosis in diabetics treated by metformin: a study of metformin elimination.

The aim of this study was to determine the characteristics of metformin elimination by dialysis. For this purpose we report the kinetic parameters during dialysis and the metformin clearance (i.e. dialysance) in four patients presenting with lactic acidosis which occurred on metformin therapy. We also studied metformin elimination in two chronically hemodialyzed diabetic patients inadvertently maintained on metformin therapy and in two chronically hemodialyzed non-diabetic patients who took a single dose of metformin before a dialysis session. Analysis of plasma concentration-time curves showed a biphasic pattern of metformin - elimination, according to a two-compartment model. We demonstrate that metformin may be removed even after reaching an equilibrium between blood and dialysate levels in a recirculating system, suggesting a storage of metformin in a deep compartment with a gradient of concentration between this compartment and the blood. Lastly, metformin dialysance appears satisfactory (68 ml/min) even in the case of relatively low blood flow; this value reached 170 ml/min under good hemodynamic conditions. In conclusion, hemodialysis efficiently removes metformin and corrects metabolic acidosis in patients with metformin-induced lactic acidosis.

Indirect clinical evidence that 1 alpha OH vitamin D3 increases the intestinal absorption of aluminum.

In a previous study we showed that 1 alpha OH vitamin D3 [1 alpha (OH)3] given to 16 hemodialyzed patients taking Al(OH)3 at a constant dose increased their plasma concentrations of aluminum [Demontis et al. 1986]. In order to choose between 2 possible mechanisms explaining this increase (increased intestinal absorption or decreased tissue storage of aluminum), we gave, in the present study, 1 alpha (OH)3 the same dose (6 micrograms per week) for the same period (4 weeks) to 15 stable hemodialyzed patients after their Al(OH)3 had been discontinued for 6 weeks. Under Al(OH)3 treatment they had a mean plasma aluminum (2.33 +/- 2.36 mumol/l) which was not significantly different from that of the patients in our former study (1.23 +/- 0.25 mumol/l). After Al(OH)3 discontinuation, plasma aluminum (measured by inductively coupled plasma emission spectrometry) decreased significantly as early as the 2nd week of the control period (1.39 mumol/l). The decrease was maintained at a plateau throughout the 5 weeks of the control period (1.38 mumol/l), the 4 weeks of 1 alpha OH vitamin (vit) D3 administration (1.40 mumol/l) and the 8 weeks of the post 1 alpha (OH)3 period (1.22 mumol/l). Plasma calcium and phosphate concentrations increased significantly with 1 alpha (OH)3 and decreased thereafter whereas plasma PTH concentrations decreased during 1 alpha (OH)2 D3 and increased after its discontinuation suggesting biological activity of 1 alpha (OH)3. Since 1 alpha (OH)3 increases plasma aluminum in hemodialyzed patients only when they are simultaneously taking Al(OH)3, it is suggested that this increase is explained by an increase of intestinal absorption of aluminum and not by a tissue redistribution of aluminum.

[Indirect evaluation of the effect of 1 alpha-hydroxyvitamin D3 on intestinal absorption of aluminum]. / Evaluation indirecte de l'effet de la 1 alpha OH vitamine D3 sur l'absorption intestinale de l'aluminium.

In a former study we have shown that 1 alpha OH vitamin D3 given to hemodialyzed patients taking A1(OH)3 at a constant dose increased their plasma concentrations of aluminium. Two mechanisms can explain this increase: increased intestinal absorption or decreased tissue storage of aluminium. We have, in the present study, given 1 alpha(OH)3 at the same dose (6 micrograms per week) and during the same duration (4 weeks) to 15 stable hemodialyzed patients after aluminium hydroxide has been discontinued 6 weeks before. Under A1(OH)3 treatment mean plasma aluminium was 2.33 +/- 2.36 mumol/l. After A1(OH)3 discontinuation, plasma aluminium decreased significantly as soon as the 2nd week of the control period (1.39 mumol/l). The decrease was maintained in plateau throughout the 5 weeks of the control period (1.38 mumol/l and, the 4 weeks of 1 OH Vit D3 administration (1.40 mumol/l). After 1 alpha OH D3 discontinuation there has been a non significant transient drop of aluminemia followed by a plateau at a level comparable to the previous plateau. Plasma calcium and phosphate concentrations increased significantly with 1 alpha(OH)3 and decreased thereafter confirming biological activity of 1 alpha(OH)3. Since 1 alpha(OH)3 increases plasma aluminium in hemodialyzed patients only when they are taking simultaneously A1(OH)3, it is suggested that this increase is mainly explained by an increase of the intestinal absorption of aluminium.

Bicarbonate haemodialysis: an adequate treatment for lactic acidosis in diabetics treated by metformin.

Lactic acidosis in diabetics on metformin therapy is rare but still associated with poor prognosis. The authors report here five cases. Three patients were initially with a cardiovascular collapse and all had an acute renal failure. Sodium bicarbonate haemodialysis therapy led to a dramatic improvement. Consciousness and hemodynamic status recovered rapidly. Severe metabolic and blood gases derangements were also rapidly corrected. Plasma metformin removal, appreciated by repeated blood samplings in 3 cases, was satisfactory. All patients survived. However, blood metformin levels remained abnormally high at the end of the dialytic therapy. In conclusion, (1) bicarbonate dialysis is an adequate treatment of lactic acidosis observed in diabetic patients treated with metformin since it rapidly corrects the acid-base disorders and partially removes metformin; (2) the sole accumulation of metformin is not sufficient to explain lactic acidosis since this latter might be corrected in spite of persisting high levels of blood metformin.

[Acute renal insufficiency caused by observed a combination of enalapril, furosemide and flurbiprofen in a patient with retroperitoneal fibrosis]. / Insuffisance rénale aiguë observée sous association énalapril, furosémide et flurbiprofène chez un malade ayant une fibrose rétropéritonéale.

The case of vasomotor parenchymal acute renal failure is reported in a patient a few days after the initiation of treatment by Enalapril which is a new converting enzyme inhibitor. No renal artery stenosis could be demonstrated, which is in contrast with the numerous cases reported up to now. However the helping roles of an incomplete obstruction by a peri-aneurysmal retroperitoneal sclerosis, of prolonged anterior treatment with flurbiprofen and of simultaneous administration of furosemide may be discussed.

Plasma renin activity, blood uric acid and plasma volume in pregnancy-induced hypertension.

UNLABELLED: Plasma renin activity (PRA), plasma aldosterone (PA), blood uric acid (BUA), plasma concentrations of catecholamines (Pcat) and plasma volume (PV) were measured simultaneously in 24 patients with pregnancy-induced hypertension. This hypertensive group was divided into labile (LH) and permanent hypertension (PH) groups according to the response of their blood pressure to home bed rest. As compared to normal theoretical values, PV was decreased in both hypertensive groups (LH = -70%; PH = -14%). As compared to a control group of 16 normotensive pregnant women, PRA was higher in LH and lower in PH whereas PA was lower in both hypertensive groups. In both hypertensive groups, BUA was higher than in the control group. No difference in Pcat was found between the three groups. In the PH group negative correlations were found between BUA and PRA, as well as between BUA and PV, but no correlation between PRA and PV nor between Pcat and BUA were found. CONCLUSIONS: LH and PH are two pathophysiologically different entities in pregnancy-induced hypertension. In PH, renin secretion is not appropriate to hypovolemia and therefore not primarily involved in the pathogenesis of hypertension. The role of hypovolemia in the increase of BUA may be discussed.

Critical role of oxalate restriction in association with calcium restriction to decrease the probability of being a stone former: insufficient effect in idiopathic hypercalciuria.

The probability of being a stone former (PSF) was calculated in 3 groups of idiopathic calcium stone formers [with normocalciuria (NC), dietary hypercalciuria (DH) and idiopathic hypercalciuria (IH)] in 4 conditions: while on a free diet; on a calcium- and oxalate-restricted diet during 4 days; after an oxalate load, while on a 1.5-gram calcium diet, and after an oxalate load while on a calcium-restricted diet. Combined calcium and oxalate restriction significantly decreased PSF only in NC and DH whereas the decrease was not significant in IH because of a concomitant significant increase in oxalate excretion. Increase of PSF with the oxalate load was significantly greater during a calcium-restricted diet than during the 1.5-gram calcium diet in all groups of patients (4, 6 and 12 times greater in NC, DH and IH, respectively). These data show the critical role of oxalate restriction when calcium is restricted in order to decrease the PSF. This combined restriction is however not sufficient in idiopathic hypercalciuric patients to decrease their PSF.