Effect of two-hour daily hemodialysis and sham dialysis on breath isoprene exhalation.

BACKGROUND: Isoprene, a volatile hydrocarbon produced by the human organism, is currently being extensively investigated because the mechanisms underlying its endogenous origin are unknown and because experiments suggest it is toxic and cancerogenous. Previous reports of increases in breath isoprene concentrations during 4-hour, thrice-weekly hemodialysis, but not during continuous ambulatorial peritoneal dialysis, prompted us to assess the behavior of isoprene in another dialytic modality, i.e., short daily hemodialysis (short DHD). Furthermore, in order to determine whether removal of solutes and/or contact of blood with the dialytic membrane influenced the metabolism of isoprene, we performed a sham short hemodialysis session in a subgroup of 8 patients (sham short HD), i.e., with blood flowing through a dialyzer but without dialysate and ultrafiltration. METHODS: The present study evaluates the effects of a two-hour short DHD and a two-hour session of sham HD on isoprene breath levels, as determined by gas chromatography before, during and after sessions. Parallel analyses of ambient air and monitoring of blood pressure and heart rate were performed. RESULTS: Both short DHD and sham DHD induced an increase in breath isoprene exhalation in all patients without being associated with significant hemodynamic variations. CONCLUSION: These findings suggest that the increase in breath isoprene after a session of hemodialysis is neither a reaction to mevalonate depletion nor to metabolic variations induced by the depurative effect, because these changes do not occur during sham HD. It is not related to hemodynamic changes because none were observed in this experimental model. The isoprene increase seems to be of metabolic origin and appears to be connected in some way with the extracorporeal circuit. These interesting findings provide a further impulse to study the biosynthetic pathways involved and to investigate the medical and biological significance of isoprene in humans.

A randomized trial of steroid avoidance in renal transplant patients treated with everolimus and cyclosporine.

In this randomized trial renal transplant recipients were treated with basiliximab, everolimus 3 mg/day, low-dose CsA. At transplantation, patients were randomized to stop steroids at the seventh day (group A) or to continue oral steroids in low doses (group B). Of the 113 patients enrolled, 65 were randomized to group A and 68 to group B. All patients were followed for 2 years. During the study 28 (43%) group A patients required reintroduced corticosteroids. One patient died, in group B. The Graft survival rate was 97% in group A and 90% in group B. There were more biopsy-proven rejections in group A (32% vs 16%; P = .044). The mean creatinine clearance was 54 +/- 21 mL/min in group A vs 56 +/- 22 mL/min in group B. Mean levels of serum cholesterol tended to be lower in group A, but the difference was of borderline significance (191 +/- 91 vs 251 +/- 188 mg/dL; P = .07). Vascular thrombosis (0 vs 5) and pneumonia requiring hospitalization (2 vs 7) tended to be more frequent in group B. Only three cases of CMV infection (1 vs 2) occurred. An immunosuppressive therapy with everolimus and low-dose CsA allows one to obtain excellent renal graft survival and stable graft function at 2 years. Early interruption of steroids in patients treated with this regimen may increase the risk of acute rejection, but neither affects graft survival nor graft function, while possibly reducing the risk of hyperlipemia and vascular thrombosis. About 60% of patients given everolimus and low-dose CsA can definitively stop steroids after 1 week.

[Acute renal failure, hemolysis and thrombocytopenia]. / Un caso di insufficienza renale acuta associata ad emolisi e piastrinopenia.

A 41-year-old male was admitted because of severe systemic hypertension and acute renal failure (ARF) that required hemodialysis (HD). Also present were hemolytic anemia, thrombocytopenia and increased plasmatic levels of aldosterone and reninic activity. The diagnostic tests performed during the recovery led to the conclusion of malignant hypertension. This case dealt with a cause of ARF, which is not currently so common; physicians should be aware of this condition especially when it is present with hemolytic anemia and thrombocytopenia, which are the microangiopathy markers.

Short daily hemodialysis: blood pressure control and left ventricular mass reduction in hypertensive hemodialysis patients.

Several retrospective and uncontrolled prospective studies reported blood pressure (BP) normalization and left ventricular mass (LVM) reduction during daily hemodialysis (DHD). Conversely, the burden of these major independent risk factors is only marginally reduced by the initiation of standard thrice-weekly dialysis (SHD), and cardiovascular events still represent the most common cause of death in hemodialysis patients. Therefore, we performed a randomized two-period crossover study to compare the effect of short DHD versus SHD on BP and LVM in hypertensive patients with end-stage renal disease. We studied 12 hypertensive patients who had been stable on SHD treatment for more than 6 months. At the end of 6 months of SHD and 6 months of DHD in a sequence of randomly assigned 24-hour ambulatory BP monitoring, echocardiography and bioimpedance were performed. Throughout the study, patients maintained the same Kt/V. A significant reduction in 24-hour BP during DHD was reported (systolic BP [SBP]: DHD, 128 +/- 11.6 mm Hg; SHD, 148 +/- 19.2 mm Hg; P < 0.01; diastolic BP: DHD, 67 +/- 8.3 mm Hg; SHD, 73 +/- 5.4 mm Hg; P = 0.01). The decrease in BP was accompanied by the withdrawal of antihypertensive therapy in 7 of 8 patients during DHD (P < 0.01). LVM index (LVMI) decreased significantly during DHD (DHD, 120.1 +/- 60.4 g/m(2); SHD, 148.7 +/- 59.7 g/m(2); P = 0.01). Extracellular water (ECW) content decreased from 52.7% +/- 11.4% to 47.6% +/- 7.5% (P = 0.02) and correlated with 24-hour SBP (r = 0.63; P < 0.01) and LVMI (r = 0.66; P < 0.01). In conclusion, this prospective crossover study confirms that DHD allows optimal control of BP, reduction in LVMI, and withdrawal of antihypertensive treatment. These effects seem to be related to reduction in ECW content.

Polymeric protein-polyamine conjugates: a new class of uremic toxins affecting erythropoiesis.

BACKGROUND: Preliminary evidence on the accumulation of polyamine-protein conjugates (PPCs) was obtained in uremic patients. The presence of these substances in the plasma of hemodialysis (HD) patients was evaluated, and their possible contribution to uremic anemia was investigated by testing the effect of PPC synthesized in vitro on erythroid cell proliferation. METHODS: Plasma PPC was measured by high-performance liquid chromatography. The in vitro synthesis of PPC from human plasma was carried out by means of the enzyme transglutaminase in the presence of either [3H]-labeled or unlabeled spermidine (SPD). After gel filtration chromatography and detection of the fractions containing [3H]SPD, the latter were tested for their effect on mononuclear bone marrow cell proliferation. RESULTS: In three out of four patients examined, mainly SPD-protein conjugates (SPD-PC) were observed to accumulate during HD. The levels ranged from 0.17 to 4.93 pmol/mg proteins before dialysis, and these values increased at 30 minutes and at the end of the dialysis up to levels 11.90 pmol/mg. SPD-PC levels in healthy controls were 1.46 +/- 0.82. SPD-PCs synthesized in vitro were recovered in two main fractions showing a molecular weight of> 100 kD (peak 1) and of approximately 30 to 50 kD (peak 3), respectively. The SPD-PC contained in peak 1 showed the greatest inhibitory effect on colony-forming units-erythroid (CFU-E) proliferation without any appreciable effect on burst-forming units-erythroid (BFU-E). CONCLUSION: We demonstrate that SPD-PC can accumulate in HD patients. These substances, which affect CFU-E proliferation, can be considered as an at yet unrevealed class of uremic toxins contributing to the onset of the uremic anemia.

Vitamin E, lipid profile, and peroxidation in hemodialysis patients.

BACKGROUND: Hypertriglyceridemia, lipid peroxidation, and abnormalities of the plasma fatty acid (PUFA) profile may be important risk factors for the atherosclerotic cardiovascular disease in hemodialysis (HD) patients. METHODS: We investigated how these factors are affected by vitamin E supplementation carried out by oral administration (clinical study 1) and dialysis with vitamin E-modified dialyzers (clinical study 2). RESULTS: In the HD patients, conditions of relative vitamin E deficiency were observed [lowered vitamin E/triglyceride (TG) ratio] in the presence of high levels of thiobarbituric acid reactants (TBARs) and decreased levels of the polyunsaturated fraction of PUFAs paired with an increased amount of monounsaturated ones (MUFA). In both studies, vitamin E supplementation significantly increased the levels of vitamin E in the plasma without affecting TG levels and provided a partial correction of TBAR levels. Of note was the relative increase in the PUFA fraction, which gave solid proof of an anti(per)oxidant effect of vitamin E supplementation in HD patients. Vitamin E supplementation was also observed to increase plasma levels of reduced glutathione and NOx (NO2 + NO3). CONCLUSION: The results suggest that vitamin E supplementation may be an effective accessory therapy to combat oxidative stress-lowering lipid peroxidation in HD patients.

Redox state, antioxidative activity and lipid peroxidation in erythrocytes and plasma of chronic ambulatory peritoneal dialysis patients.

Red blood cells and plasma reduced and oxidized glutathione levels, glutathione peroxidase (GSH-Px) activity, thiobarbituric acid reactants (TBAR) of both chronic ambulatory peritoneal dialysis (CAPD) patients and a matched control group were investigated in this study. Oxidized and reduced pyridinic nucleotides in red blood cells (RBC), in which NADPH is a direct expression of hexose monophosphate shunt function, were also studied. The results obtained indicate that RBC and plasma are exposed to oxidative stress in CAPD. This condition is characterized by a decreased GSH/GSSG ratio, particularly evident in RBC as a consequence of the GSSG accumulation. Lipid peroxidation is increased, as indicated by raised TBAR levels, and reduced pyridinic nucleotides are decreased. Increased GSH-Px levels and unmodified or slightly increased GSH content were observed in the RBC but not in plasma, which showed decreased GSH and unmodified peroxidase activity. Peroxidase correlated positively with TBAR levels in the RBC lysates. In a subgroup of patients treated with erythropoietin (vs. untreated patients and controls) no differences were observed in the glutathione-related parameters studied. These data suggest that a mechanism for adaptation to oxidative conditions may be present in CAPD and its effects on RBC integrity are discussed in comparison with the hemodialysis conditions previously studied.

Accumulation of vitamin E metabolites in the blood of renal failure patients.

BACKGROUND & AIMS: Carboxyethyl-hydroxychromans (CEHC) are hydrosoluble vitamin E metabolites excreted through the renal filter. In this study we investigated the effect of the kidney damage on the blood levels of CEHC. METHODS: Plasma levels of alpha-CEHC, gamma-CEHC and their precursors (namely, alpha-tocopherol and gamma-tocopherol) were measured by HPLC with electrochemical detection in chronic (CRF) and end-stage renal failure patients on regular hemodialysis (HD) before and after dialysis. CRF patients (n = 26) were divided into three subgroups with different extent of kidney damage as measured by the intervals of creatinine clearance (CrCl, in ml/min): (a) 2-10, (b) 10-20, and (c) 20-45. HD patients (n = 8) did not show residual renal function. In all the subjects the intake of vitamin E (as alpha-tocopherol) was assessed using a food frequency questionnaire. In the HD group, the plasma concentrations of ascorbic and uric acid (AA and UA, respectively), total thiols, the total antioxidant status (TAS) and reactive carbonyls were also measured. RESULTS: The progressive deterioration of the kidney function in the different groups of patients produced an exponential increase of both alpha-CEHC and gamma-CEHC in plasma. Compared with healthy controls (alpha-CEHC = 20.1+/-13.4 and gamma-CEHC = 230.6+/-83.0 nmol/l) the levels of CEHC approximately doubled in patients with CrCl < or = 20ml/min (42.4+/-20.2 and 424.5.5+/-174.4; P <0.05 or higher in both) and reached a 3-fold maximum increase in HD patients (77.3+/-45.7 and 636.6+/-219.3). The hemodialysis provided a significant, but only a transient, correction of CEHC accumulation (44.8+/-23.5, 364.2+/-189.9). The HD patients showed lower intake and levels of vitamin E (alpha-tocopherol = 5.1+/-1.0 and gamma-tocopherol =0.32+/-0.11 micromol/mmol cholesterol; P <0.05) compared to healthy controls (5.8+/-0.8 and 0.43+/-0.14), but in the CRF patients tocopherol levels were normal or only slightly decreased even though approximately half of the subject had lowered vitamin E intake. When the entire patient population was considered, the blood concentrations of parental tocopherols and CEHC did not correlate. The HD patients before dialysis showed a marked decrease of TAS/UA, AA and thiols levels, while UA and free carbonyls significantly increased. After dialysis, the depletion of AA and thiols further worsened and also UA and TAS/UA decreased, but free carbonyls slightly increased. CONCLUSIONS: The results other than to confirm the key importance of the renal route for the excretion of CEHC, demonstrate that CEHC cannot be reliably used to investigate vitamin E biokinetics and transformation without a careful examination of the renal function. CEHC accumulation does not seem to influence the antioxidant status in the plasma of HD patients. Further studies are requested to establish whether such an increase in blood CEHC concentrations might be harmful or could contribute to the biological functions of the vitamin E in uremia and dialysis patients.

Survival of vascular access during daily and three times a week hemodialysis.

AIM: A major cause of morbidity for hemodialysis patients is vascular access failure and/or occlusion. It is commonly believed that an increased frequency of dialysis sessions, among other factors, might lead to a higher rate of fistula complications. MATERIALS AND METHODS: To evaluate if patients on daily hemodialysis carry a higher risk of vascular access occlusion, we examined the incidence rate of access occlusion and the survival function of native vascular accesses in patients undergoing daily dialysis (DD; n = 24) as compared to patients on standard three times a week hemodialysis (TWD; n = 124). RESULTS: The mean follow-up time was 3.6 years. In the TWD group 42 patients had a first-access closure, whereas only 2 patients out 24 had a similar event in the DD group. The proportion of first-access closure was 33.9% for TWD and 8.3% for DD (p < 0.01). The incidence rate was 9.8 (95% CI: 7.2 -13.2) and 2.2 (95% CI: 0.4 - 7.1) events per 100 patient-years for TWD and DD, respectively. The rate difference was 7.6 (95% CI 3.4 - 11.9) events per 100 patient-years, and the unadjusted risk ratio was 4.5 (95% CI: 1.2 - 16.9; p < 0.01). The mean vascular access survival before closure was 3.3 years in TWD and 3.7 years in DD. Survival curves, obtained considering the first-access closure as the endpoint, showed a significant difference between DD and TWD (log-rank 5.16; p < 0.05). In a Cox-proportional hazard model the relative risk (RR) of vascular-access closure in TWD remained significant (RR = 4.3; 95% CI 1.1 - 18.2) after adjustment for age. CONCLUSION: The results of this observational study, conducted on a limited number of DD patients, suggest that daily dialysis might not have an adverse prognostic significance for access closure.

Reduction of renal functional reserve in kidney transplant recipients: a possible role of arachidonic acid metabolism alterations.

AIM: Renal functional reserve (RFR), resulting from an increase in glomerular filtration (GFR) after protein load, is a matter of debate. In kidney transplant recipients most studies have failed to show conclusive results, reporting either the absence, the reduction or the presence of renal reserve in normo-functioning kidneys. The aim of this study was to investigate RFR in kidney transplant patients as well as the possible hormonal vasoactive alterations underlying the reduction of renal reserve reported in some patients. PATIENTS AND METHODS: We studied 8 controls and 25 patients, the latter with no history of acute rejection for at least 12 months and GFR >50 ml/min. The 25 patients were divided into 2 groups based on the presence (10) or the absence (15) of RFR. RESULTS: Both the RFR group and the controls experienced a similar increase of GFR after oral protein load: 24.3 +/- 15.57% vs 24.4 +/- 10.8%. The group without RFR showed a paradoxical reduction of GFR after oral protein load: 13.3 +/- 13.2% (p <0.001). We analyzed the filtration fraction (FF) and observed that the group without RFR had higher values than the group with RFR and the controls: 0.35 +/- 0.11 vs 0.29 +/- 0.07 (p = 0.01) and vs 0.26 +/- 0.02 (p = 0.04). The hyperfiltration state observed in the group without RFR was sustained by a high level of thromboxane. The urine ratio TxB2/6ketoPgF1alpha was higher in the group without RFR than in the RFR group 0.78 +/- 0.2 vs 0.64 +/- 0.1 (p = 0.01). This ratio decreased only in the RFR group after a meat meal. In all the patients, changes of TxB2/6ketoPGF1alpha were inversely correlated to changes of GFR after a meat meal (r = -0.6, p = 0.01). CONCLUSIONS: In conclusion, these data demonstrate that kidney transplant recipients with good organ function can be grouped according to the presence of RFR. RFR appears to be inversely correlated with the TxB2/6ketoPGF1alpha ratio, and its decrease seems to be linked to the failure of thromboxane to decrease and prostacycline to increase after a meat meal.

Continuous ambulatory peritoneal dialysis connection systems.

The history of the various connection systems proposed and tried during the first 15 years of clinical application of continuous ambulatory peritoneal dialysis (CAPD) is reviewed. In order to understand the reasons for their success or lack of success, the main technical and operating characteristics regarding their efficacy in preventing peritonitis are examined in detail, together with a range of other pros and cons (i.e., reliability, simplicity, ease of use, cost, aesthetical aspects). The result is an updated state-of-the-art review in the field of CAPD connectology, with a look at future trends.

Better preservation of cognitive faculty in continuous ambulatory peritoneal dialysis.

We employed the so-called event-correlated potential (ECP) P300, a neurophysiological test which explores the circuits of attention and memory in the brain and is altered in subjects with a dismetabolic or degenerative encephalopathy, in order to evaluate the cognitive faculty in two groups of uremic patients [18 on continuous ambulatory peritoneal dialysis (CAPD), 15 on hemodialysis (HD)] comparable with respect to age and time on dialysis. The values of latency (msec) of P300 resulted in CAPD patients 356 +/- 26 in CZ (central zero electrodes) and 357.5 +/- 25 in PZ (parietal zero electrodes), not significantly different from the values in normal controls (341 +/- 14.5 in CZ and 340 +/- 15.6 in PZ) and in HD patients postdialysis (354 +/- 24.4 in CZ and 354 +/- 25.6 in PZ). On the contrary, the predialytic values of HD patients (384 +/- 25.6 CZ and 385 +/- 25.5 in PZ) were significantly different from the postdialytic values and from the values of CAPD patients and controls (p < 0.01). These results support the conclusion that HD is able to restore a normal cognitive faculty only transiently in the postdialytic phase, while CAPD maintains this important function steadily close to the normal range, thus being clearly better than HD.

A new self-locating peritoneal catheter.

OBJECTIVE: Peritoneal catheters often become dislocated, and this may lead to malfunction. Since it is not usually possible to bring them back into their correct position, they must be replaced. With the aim of preventing this complication, we designed a new catheter. DESIGN: The new catheter has the same form as the Tenckhoff catheter except for a small increase in external diameter of the last 2 cm, made possible by the high specific weight of a small 12-g tungsten cylinder incorporated in the Silastic at the abdominal end. The new catheter may be inserted by a percutaneous technique. SETTING: University hospitals of Siena and Perugia, Italy. PATIENTS: In the last three years, 32 of these catheters have been implanted for a total experience of 468 patient-months. Their position was checked on insertion and every two months thereafter by radiography; 26 Tenckhoff catheters (415 patient-months) were studied at the same time. Insertion was performed surgically and by a percutaneous method. The frequency of cuff extrusion, exit-site infections, leakage, and peritoneal infection were noted, together with peritoneal function, which was evaluated by KT/V and weekly creatinine clearance one month after catheter insertion; the tests were repeated when dislocation occurred and at the end of the trial. RESULTS: No dislocations occurred with the self-locating catheters, whereas nine dislocations occurred in control patients (p = 0.0003). There were no significant differences with respect to controls for cuff extrusion, exit-site infections, leakage, peritoneal infection, and peritoneal function. CONCLUSIONS: The presence of a small weight at the catheter up prevents displacement completely, keeping the intraperitoneal part of the catheter in place.

Clinical experience with a 39 mmol/L bicarbonate-buffered peritoneal dialysis solution.

OBJECTIVE: To investigate the effect on the patient's acid-base status of a 39 mmol/L bicarbonate-buffered continuous ambulatory peritoneal dialysis (CAPD) solution. DESIGN: This was an open, controlled, cross-over, two-center study in 9 patients. After three months of treatment with a 34 mmol/L bicarbonate-buffered solution (t0) patients were switched to a 39 mmol/L bicarbonate-containing solution for four weeks. At the end of the study period (t4) patients were again treated with a 34 mmol/L bicarbonate-buffered CAPD solution for one month (t8). RESULTS: Mean venous plasma bicarbonate level significantly increased during the study and decreased at the baseline level during the control period (t0 = 22.94 +/- 2.54, t1 = 26.74 +/- 3.07, t2 = 28.47 +/- 2.68, t3 = 28.11 +/- 3.56, t4 = 28.71 +/- 3.27, t8 = 24.94 +/- 2.56). Arterial blood pH and plasma bicarbonate significantly increased during the study and significantly decreased at the end of the control period (pH: t0 = 7.37 +/- 0.04, t4 = 7.42 +/- 0.04, t8 = 7.37 +/- 0.06. Bicarbonate: t0 = 21.97 +/- 2.57, t4 = 25.85 +/- 2.02, t8 = 21.87 +/- 2.89). The changes in plasma bicarbonate during the study period were inversely correlated with the metabolic acid production calculated from the protein catabolic rate and with the apparent distribution space for bicarbonate (ABS) of patients. CONCLUSIONS: The 39 mmol/L bicarbonate-buffered CAPD solution improved the patient's acid-base status. Potential undesirable metabolic alkalosis could be prevented by analyzing the ABS and the metabolic acid production of patients.

Bicarbonate versus lactate buffer in peritoneal dialysis solutions: the beneficial effect on RBC metabolism.

OBJECTIVE: Using the erythrocyte as a model for other kinds of cells not directly exposed to peritoneal dialysis (PD) solutions, we investigated the tolerance of the cell metabolism to lactate and bicarbonate buffers. DESIGN: We studied, in vivo (in two groups of 5 PD patients each) and in vitro, the Embden-Meyerhof pathway (EMP) because it represents a potential target for the unphysiological effects of lactate or bicarbonate buffers. The EMP is the main glucose-utilizing route in the red blood cell (RBC), producing energy and reducing power. METHODS: The enzymatic activities of the key steps in the glycolytic pathway and the energy charge (EC), determined by the levels of phosphorylated adenine nucleotides, were investigated spectrophotometrically and by high performance liquid chromatography (HPLC) in two groups of patients undergoing lactate (L-group) and bicarbonate (B-group) PD, respectively. The in vitro effects of both bicarbonate and lactate buffers on some EMP enzyme activities and energy production were determined. Cellular pH (pHi) was also investigated. RESULTS: The B-group showed an EC value near the control levels, while in the L-group a significantly lower EC value was observed (t-test: p < 0.05 vs both B-group and controls). The key enzymes in the EMP, and in particular hexokinase, were higher in the L-versus B-group (p < 0.03 for the comparison of the Hk mean values). As demonstrated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis, the bound form of glyceraldehyde-3-phosphate dehydrogenase (G-3-PD), an inactive form of this EMP enzyme, was significantly higher in the L-group with respect to the B-group (p < 0.004). In the in vitro experiments, high lactate concentrations acutely inhibited the key enzymatic steps of glycolysis, producing a significant decrease in glucose consumption and adenosine triphosphate production. These effects were not observed when bicarbonate was used in the incubations. Both in vivo and in vitro lactate, but not bicarbonate, induce a significant drop in pHi (p < 0.05). Decreased levels of pHi like those observed in the lactate-incubated RBC were demonstrated to be able to inhibit G-3-PD activity (25 +/- 2%) here used as an indicator of the actual decrease in pH. CONCLUSION: This study provides evidence for a damaging action of lactate with respect to bicarbonate buffer on the RBC metabolism. This condition was demonstrated observing a cell energy depletion, which coincides in vitro with an acute EMP impairment; the lactate accumulation together with the consequent lowering of pHi seem to be responsible for this effect, which was not observed when bicarbonate was used instead of lactate.

Polyacrilonytrile versus cuprophan membranes for hemodialysis: evaluation of efficacy and biocompatibility by platelet aggregation studies.

The short- and long-term effect of hemodialysis with two different membranes -- cuprophan and polyacrilonytrile -- on platelet aggregation has been investigated in 12 uremic patients undergoing extracorporeal dialysis, passing from one treatment to the other. Cuprophan membranes failed to correct the defective platelet aggregation of uremia, and their thrombogenicity was documented by a fall in platelet count and further impairment of platelet aggregation during dialysis. On the contrary, polyacrilonitrile membranes showed the capacity to correct completely but transiently the platelet aggregation, without changes in platelet count. The results indicate that polyacrilonytrile membranes show a better biocompatibility toward platelets than cuprophan membranes.

Biofiltration with buffer-free dialysate.

The presence of acetate in the dialysate appears to be superfluous in the new depurative technique indicated as biofiltration, which consists in a standard hemodialysis with high ultrafiltration combined with the reinfusion of 3-4 1/2 liters of solution containing bicarbonate. The presence of acetate could in fact be contraindicated by a number of potential side effects, metabolic, cardiovascular and biological. Hence, starting from the consideration that in standard biofiltration a buffer is already infused directly as bicarbonate, we tried to overcome the potential hazards of the acetate-containing bath simply by using a dialysate without acetate and by increasing the concentration of bicarbonate in the reinfusate. A cumulative clinical experience of 20 months in 4 patients proved the feasibility and safety of the technique and suggests further advantages over standard biofiltration (better control of acid-base equilibrium, better cardiovascular stability.

Control of uremic neuropathy by equilibrium peritoneal dialysis.

Motor nerve conduction velocity (MNCV), sensory nerve conduction velocity (SNVC) and distal motor latencies times (DMLT) were evaluated both in upper and lower limbs in three groups of 15 patients of comparable age, treated respectively by extracorporeal dialysis (HD), continuous ambulatory peritoneal dialysis (CAPD) and combined peritoneal dialysis (CPD) for comparable sufficiently long periods. Moreover, MNCV was monitored longitudinally in two groups of patients shifted from CAPD to HD and vice versa. The results show a significant superiority of peritoneal dialysis and particularly of CAPD with respect to HD in controlling uremic neuropathy.

Polycentric 384-month study of biofiltration (BF) with AN69s.

Polycentric 384-month study of biofiltration (BF) with AN69s. Since January 1984, 39 uremic dialyzed patients have been included in a randomized prospective study, to evaluate the clinical utility of BF. The trial lasted 9.85 months/pt (384.15 months of total observations) and patients admitted had some not well controlled clinical signs: major acidosis, intradialytic cardiovascular instability, intolerance to acetate dialysis, hypercatabolism, neuropathy, etc. We obtained some positive effects: the incidence of intradialytic hypotension decreased 26.6%; interdialytic body weight gain fell from 3.1 to 2.7 kg (p less than 0.05) and the dialytic time per week was reduced from 12.3 to 10.0 hours (p less than 0.01). At the same time dry body weight increased from 62.4 to 64.6 kg with worthwhile improvement of the acid-base status (ABS) in all patients. This controlled trial showed that BF is particularly useful for patients suffering from severe acidosis and/or cardiovascular instability.

Effects of chronic biofiltration with PAN membranes on acid-base status: polycentric study.

Effects of chronic biofiltration (BF) with PAN membranes on acid-base status (ABS): polycentric study. From the 39 cases in a polycentric study we selected 13 patients with metabolic acidosis (pH 7.23 +/- 0.03), marked reduction of plasma bicarbonate (15.4 +/- 2.2 mEq/l) and hyperkalemia (6.2 +/- 0.6 mEq/l). BF was performed with a continuous post-dilutional supply of HCO3 (85 mmol/h), and attained rapid normalisation of blood bicarbonates and serum potassium during the treatment. After 6 months of BF treatment the pre-dialytic ABS showed remarkable improvement, and values were normal after one year. The remaining 26 patients in the polycentric study, treated by chronic BF without severe acidosis, showed good dialytic tolerance. In 15 of them the supply of bicarbonate was too high (because of moderate post-BF alkalosis) and we had to reduce the buffer inflow to about 50 mmol/h.