Phenotypic and genotypic risk factors for cardiovascular events in an incident dialysis cohort.

Cardiovascular disease (CVD) remains the major cause of death in patients with end-stage renal disease (ESRD). Traditional risk factors do not explain the high prevalence of CVD in this population, and other non-traditional cardiovascular (CV) risk markers have now been described. Therefore, the potential relationship between CVD and phenotypic and genotypic risk markers was investigated prospectively in incident dialysis patients cohort. The 279 patients (244 on hemodialysis, 35 on peritoneal dialysis) within the Diamant Alpin Dialysis Cohort Study were investigated. Phenotypic and genotypic parameters were determined at dialysis initiation, patients monitored over a 2-year period, and CV events (morbidity and mortality) recorded. Globally, 82 CV events occurred and 26 patients (9.3%) died from CVD, whereas 28 (10%) died from non-CV causes. Previous CV events were strongly predictive of CV events occurrence, whatever patients had had one (hazard ratio (HR) 2, 95% confidence intervals (CI) 1.1-3.5) or more (HR 3.9, 95% CI 2.1-7.1) CV accidents before starting dialysis. Both lipoprotein(a) (HR 1.67, 95% CI 1-2.5) and total plasma homocysteine at cutoff 30 micromol/l (HR 1.7, 95% CI 1.1-2.8) were independent predictors of CV events outcome. In the subgroup of patients with homocysteine < 30 micromol/l, methylenetetrahydrofolate reductase (MTHFR) TT was the sole biological parameter predictive of CV event outcome (HR 2.5, 95% CI 1.1-10, P = 0.03). ESRD patients who enter chronic dialysis with a previous CV event, high total homocysteinemia levels, or MTHFR 677TT genotype must be considered at high risk of incident CV events.

[SIN survey on quality control of dialysis water in Italy]. / Indagine SIN sui controlli delle acque di dialisi in Italia.

BACKGROUND: The importance of high quality water for dialysis is well established. This study aimed to obtain a picture of the Italian situation to develop national guidelines. METHODS: Questionnaire analysis was used to assess water quality control protocols and types of chemical and microbiological parameters monitored. Regions with responses from at least half the units were considered for the study. RESULTS: Eighteen out of 20 regions fulfilled the inclusion criteria; 297/469 dialysis units answered the questionnaire (5208 dialysis beds, 18213 patients). Eighty-one percent of Italian units follow a regular water quality control program. The reverse osmosis outlet is the sampling point used most for assessing chemical and microbiological parameters. The most common frequency in monitoring is < or =6 months. Fifteen chemical items, suggested by the Italian Farmacopea Ufficiale (FU), are periodically controlled by at least half the units. Aluminum is measured in about 70% of units, chloramines and volatile halogenated hydrocarbons, respectively, in 42 and 30% of units. According to the FU, bacterial counts at 22 degrees C (84%) and endotoxin determinations (60%) are the most common microbiological analyzes. CONCLUSIONS: The survey demonstrated protocol differences among the units, confirming the need for Italian guidelines to ameliorate and standardize dialysis water monitoring. More than half the units are following the FU, but we cannot rule out less strict monitoring only in non-participating units.

[Hemodialysis access recirculation]. / Il fenomeno del ricircolo in corso di emodialisi (Hemodialysis Vascular Access Recirculation).

Vascular access recirculation (R) allows the evaluation of the adequacy of the extracorporeal blood circuit in dialysis patients. The test verifies the correct needle position in patients with arterovenous fistulae (AVF) and the effective function of central venous catheters. In clinically uncomplicated native fistulae, a normal R test could avoid more complex procedures like blood flow measure or angiography. The AVF recirculation has two components, vascular access recirculation (AR) and cardiopulmonary recirculation (CPR). While the first phenomenon is well known, the second remained undetected for many years resulting in wrong R calculations with false positives. Using the correct formula, the great majority of AVF resulted in zero recirculation. The presence of R reduces the dialysis efficiency to critical levels, mainly in unsuspected cases. Among the numerous available R tests, the urea test is the oldest and historically the most commonly used method, but unfortunately it is labor intensive, with low sensitivity and specificity and with delayed results. The "ultrasound dilution"method is considered the gold standard, easy to perform, with good repeatability, but it is expensive requiring a specific device. Finally, the glucose infusion test (GIT) is a new low-cost test with immediate results and a very low detection limit, with good repeatability and high specificity and sensitivity.

Long nocturnal dialysis.

BACKGROUND/AIMS: The continuous growth of the dialysis pool in our unit induced us to organize a third long nocturnal dialysis (LND) session, considering the excellent survival and rehabilitation results reported with this method. This paper analyzes the results and assesses the role of LND among the different dialytic treatment options. METHODS: Out of 18 patients on LND, 13 (12 males and 1 female, mean age 52 +/- 13 years, time on dialysis 21.8 +/- 23.8 months) with >6 months' experience were studied, and 9 underwent a further metabolic evaluation. LND was performed using 1- to 1.4-m(2) Hemophan membranes, bicarbonate buffer, 200-250 ml/min blood flow, and 300-500 ml/min dialysate flow, 8 h three times a week. Kt/V and protein catabolic rate (3-point classic urea kinetics), postdialytic weight, serum albumin, total protein, hemoglobin, Ca(2+), phosphate, intact parathyroid hormone, bioimpedance body water, blood pressure, and drug use (antihypertensives, phosphate binders, erythropoietin, vitamin D, hypnotics) were evaluated in each patient during hemodialysis and LND. In the metabolic study (done twice), sodium (compared with the Kimura model), potassium, phosphate, and urea were analyzed in blood and inlet and outlet dialysate after 0, 2, 4, 6, and 8 h. RESULTS: The mortality was low (1 death every 247 patient-months). After 19 +/- 8.1 months of LND, the postdialytic weight rose from 68.5 +/- 9.6 to 70.8 +/- 10.7 kg (p < or = 0.01), and the hemoglobin concentration rose from 10.8 +/- 2.2 to 11.8 +/- 1.8 g/dl (p < or = 0.05); phosphate dropped from 5.6 +/- 2.0 to 4.4 +/- 1.3 mg/ dl (p < or = 0.01) and the systolic blood pressure from 152 +/- 15 to 143 +/- 19 mm Hg (p < or = 0.05). In the metabolic study, the sodium profile was significantly lower during the last 4 h than in the Kimura model. The potassium concentration, stable between 4 and 6 h, rose against the gradient during the last 2-hour period. The behavior of sodium and potassium during the last part of the dialysis session can be taken to indicate exhaustion of the sodium/potassium pump. Phosphate showed a gradual reduction with no intradialytic and only a moderate postdialytic rebound. The postdialytic urea rebound was 23.4%. CONCLUSIONS: LND is a useful additional tool for nephrologists in treating chronic renal failure, it is easy to organize, and it shows overall good results. Together with other dialysis methods, this schedule permits individualized treatment for each uremic patient.

Glucose infusion test: a new screening test for vascular access recirculation.

BACKGROUND: Vascular access recirculation is an important cause of diminished dialysis efficiency. We propose a new screening test based on glucose infusion as a tracer for recirculation. METHODS: The glucose infusion test (GIT) protocol comprises a basal blood sample (A) from the arterial port, a 5 mL bolus of 20% glucose into the venous chamber (time 0), followed by a second sample (B) in four seconds (from 13 to 17 s with QB 300 mL/min) from the same port. The blood glucose level is determined at the bedside on A and B with a reflectance photometer (CV 1.8%). Interpretation of the test is straightforward: If B = A, there is no recirculation, whereas if B > A, recirculation can be calculated from the regression equation: 0.046 x (B - A) + 0.07, obtained from in vitro tests reproducing artificial recirculation at 0, 5, and 10%. To validate this new method in vivo, we compared GIT and the urea test on 39 hemodialysis patients, obtaining a good correlation (r = 0.93). The two tests were considered positive (recirculation present) when the lower 95% confidence intervals were more than zero. RESULTS: Our patients were divided into two groups: those with (22 out of 39, mean recirculation 11.8%) or without recirculation (17 out of 39, mean 0.06%). The urea test did not recognize 7 out of 22 patients because they had a small recirculation below the urea test limit of detection. CONCLUSIONS: GIT was more sensitive (detection limit 0.3%), simpler, and immediate in showing the results than the urea test. It is an accurate and low-cost technique for screening and follow-up of vascular access in a dialysis unit.

GIT (Glucose Infusion Test): polycentric evaluation of a new test for vascular access recirculation.

Introduction. Vascular access recirculation (AR), which is often unacknowledged, remains an important cause of inadequate dialytic dose. The glucose infusion test (GIT) is a new method for detecting and quantifying AR. This paper reports on a polycentric evaluation of the new test and a comparison with the classical Urea-test (UT). Methods. GIT protocol comprises withdrawal from the arterial port (sample A), injection into the venous drip chamber of 1 g glucose in 4 seconds, withdrawal from the arterial port (sample B) continuously from 13 to 17 seconds. Glucose is determined on A and B by a reflectance photometer. If B = A then there is no recirculation. If B exceeds A by at least 20 mg/dl there is recirculation. AR quantification: AR% = (B-A) / 20. GIT was performed on 623 patients from eleven dialysis centers to screen the patients for AR. Subsequently, GIT and Urea-test (UT) were compared in 189 paired tests. The reproducibility of GIT and UT was studied in 28 paired tests performed in sequence. Results. The screening test by GIT was positive in 68 cases (11 %). The majority of positivities was found in central venous catheters (CVC, 27/50 cases, 54 %), whereas only 7 % of artero-venous fistulas (AVF) were positive. In the CVC group, Tesio catheters were more frequently positive compared to Dual Lumen Catheters (64 % vs. 29 %). The comparison GIT - UT showed that results matched in 162 tests (79 negative and 83 positive both by GIT and UT), showing that on the grounds of UT, GIT has high sensitivity and specificity. In 27 tests GIT was positive, but UT negative. This disagreement is due to the different minimal limit of detection, 1 % for GIT and 5% for UT. The reproducibility was greater with GIT than with UT with a lower D% (respectively -0.6 +/- 2.5 and -0.4 +/- 6.1 %, p<0.001) and a lower coefficient of variation (17 vs 33 %). Conclusions. The screening of 623 patients by GIT confirmed that AR in AVF is normally absent, whereas an un-expectedly high frequency of moderate AR in CVC was found. The GIT-UT comparison showed that the new test is simple and immediate, and gives results with higher accuracy, sensitivity and reproducibility than UT.

Measurement of vascular access recirculation unaffected by cardiopulmonary recirculation: evaluation of an ultrasound method.

Recently developed devices provide detection of access recirculation (AR) and cardiopulmonary recirculation (CPR) by optical, thermal, conducimetrical, and ultrasound methods (USM). We evaluated the last one both in vitro reproducing AR by a bypass pump and in vivo. In vitro, the USM sensitivity was about 5%. In vivo, the USM was compared with the traditional urea method (UM) in 69 patients. 8.7% of the cases resulted positive by both UM and USM. One case was USM positive and UM negative. The UM sensitivity threshold was 6-10%. The accuracy (in vitro) and the repeatability (in vivo) of the USM were satisfactory. USM clearly distinguished AR from CPR. In conclusion, AR determination by USM, avoiding misleading interferences with CPR, is a rapid, easy, and noninvasive method to routinely exclude a potential cause of reduced dialytic efficiency.

Relation between blood pH and ionized calcium during acute metabolic alteration of the acid-base balance in vivo.

We induced metabolic alkalosis and acidosis in 10 healthy volunteers in order to analyse in vivo relation between pH and ionized calcium (cCa2+). In the alkalinization test, 2.7 mol/kg NaHCO3 was injected. In the acidification test, volunteers took 4 mmol/kg NH4Cl. Blood pH and cCa2+ (mmol/l) mean values (SD) baseline, after alkalinization and acidification tests, were: 7.363 (0.018), 7.456 (0.031), 7.244 (0.031), 1.27 (0.03), 1.14 (0.03) and 1.38 (0.04). Mean slope of regression log cCa2+/pH was -0.39 (SD 0.11). Such a slope differs after in vivo or in vitro changes, due to the in vivo rapid restoration of equilibrium between the plasmatic and interstitial compartments following changes in water and electrolyte concentrations. The type of acid-base alteration-respiratory or metabolic-influences pH changes, and consequently the regression slope. The in vivo slope for log cCa2+/pH in normal subjects (-0.21) is much the same as in acute respiratory alterations (-0.17), whereas it differs in acute metabolic alterations (present study). Bicarbonates play different roles: the same changes in pH cause greater changes in cCa2+ after acute metabolic rather than respiratory alterations. Ca2+ homeostasis is maintained in acute respiratory acid-base imbalance, despite wide shifts in pH, whereas in acute metabolic alterations even small pH changes have striking repercussions on cCa2+. The experimental angular coefficient for in vivo acute metabolic acid-base alterations differs from the theoretical one calculated by Thode's differential equation (-0.25).

[Diagnostic aspects in the determination of antineutrophil cytoplasmic antibodies]. / Aspetti diagnostici nella determinazione degli anticorpi anti citoplasma dei neutrofili.

We propose a four step flow-chart to define ANCA positivity and antigenic target. 1st step: indirect immunofluorescence test on ethanol-fixed human granulocytes (IIF-E), as screening test. Different staining patterns can be observed: a granular cytoplasmic fluorescence (C-ANCA), a smooth or fine granular perinuclear fluorescence (P-ANCA) and an intermediate pattern (X-ANCA). Antinuclear antibodies (ANA) may mimic P-ANCA. 2nd step: IIF test on formalin-fixed human granulocytes (IIF-F) differentiates true P-ANCA from ANA: most of P-ANCA show cytoplasmic pattern, whereas ANA are negative. 3rd step: IIF test on monkey liver sections (IIF-M) investigates simultaneous ANA and P-ANCA positiveness. P-ANCA positive sera show an exclusive reactivity with neutrophils infiltrating the portal tract, whereas ANA react with hepatocytes nuclei. 4th step: to characterize antigenic target, a solid phase assay, using purified proteins as substrates, is performed. We found 17 C-ANCA (6 PR3, 3 MPO, 1 Lys, 1 Cat G and 6 unknown antigens) out of 173 patients screened with IIF-E. 21 P-ANCA positive sera have been investigated by IIF-F test: 15 showed a cytoplasmic pattern; EIA test gave the following results: 6 MPO, 2 LF, 5 unknown antigens; 2 cases were positive for two antigens, MPO & LF. Using IIF-M on the 6 IIF-F negative sera, we observed: 2 false positives (ANCA-/ANA-), one ANCA+/ANA+ (antigen LF), 3 ANCA+/ANA- (unknown antigens). The flow chart suggested allows to analyse in detail ANCA, using easily available commercial kits.

[Use of dual energy X-ray absorptiometry (DEXA) in the determination of total body water in patients undergoing chronic dialysis]. / Impiego della dual energy X-ray absorptiometry (DEXA) per la determinazione dell'acqua corporea totale nei pazienti in trattamento dialitico cronico.

In order to assess Total Body Water (TBW), three methods are compared, in 18 patients on regular dialysis treatment: DEXA, Bioimpedance Analysis (BIA) and urea Kinetic Volume (V urea). The mean difference between gravimetric weight and Total Body Mass (TBM) DEXA is closed (1.04 kg, SD of differences 0.4 kg). The mean difference between delta pre-post HD gravimetric weight loss (2.6 kg) and delta pre-post TBM DEXA is--0.03 kg (SD 0.28). TBW measured with the three methods are (Liters): TBW DEXA = 31.2 (SD 5.2), TBW BIA = 29.7 (SD 5.2), TBW V urea = 29.1 (SD 4.8). TBW comparisons between the three methods are (Liters): TBW DEXA-TBW BIA = mean 1.5 (SD 3.8), r = 0.73. TBW DEXA-TBW V urea = mean 2.1 (SD 2.2), r = 0.88. TBW BIA-TBW V urea = mean 0.6 (SD 3.6), r = 0.80. Hydration index of lean body mass, calculated by assuming V urea as standard, is 0.69 (SD 0.05), range 0.62-0.77, in agreement with others studies. In conclusion DEXA, a useful method for body composition and nutritional status assessing, represents a new tool for measuring hydration status, combined with others TBW evaluation formulas (BIA or V urea).

On-line dialysate urea monitor: comparison with urea kinetics.

The outputs of a new on-line dialysate urea monitor (UM) were compared to a urea kinetic model (UKM) and to dialysis direct quantification (DDQ) in 13 patients. As for urea extraction and predialysis urea level, a good degree of correspondence was found between UM and laboratory data. Kt/VUM (1.21) is intermediate between Kt/VUKM (1.28) and Kt/VUKM using the post-rebound urea value (1.14) or Kt/VDDQ (1.14). Passing and Bablok regression analysis indicated no systematic error between Kt/VUM and Kt/VDDQ. The percentage differences in nPCR by UM, UKM and DDQ were not significant, but the standard deviations were wide. The UM approach is very simple and practical, avoiding blood sampling, laboratory analysis and data handling. It is reliable enough for clinical practice. Compared with traditional urea kinetics, Kt/V computation by a mathematical elaboration of the dialysate urea profile drawn from several points theoretically invites fewer errors due to the analytical procedure.

[Effect of dialytic treatment and the relation between erythrocyte urea and plasma urea]. / Effetto del trattamento dialitico sul rapporto tra urea eritrocitaria ed urea plasmatica.

The existence of an intraerythrocytic binding between haemoglobin and urea is known; it determines, in normals, a higher erythrocyte than plasma urea concentration; this binding, in vitro, is progressive for an urea concentration range of 10-400 mg/dl. The only data found relating to dialysis patients, are reported by Nolph et al.; they indicate a decrease in the plasma-blood urea ratio during the blood transit through the dialyzer and a different ratio in comparison with normals, but in our opinion the method used to measure urea concentration was unsuitable. We determined urea distribution ratios by measuring, in blood and plasma, water and urea concentration in uremic inflow and outflow blood samples during dialysis. Our data indicate 1) an increase in outflow erythrocyte water (H2Oe inflow: 0.659, H2Oe outflow: 0.671 P less than 0.01) induced by a different erythrocyte osmotic gradient; 2) a not different ratio between urea of erythrocyte water and urea of plasma water in inflow and outflow samples of dialysed patients and in normals (respectively 1.06, 1.16, 1.13 p = n.s.). Our data from normal and uremic patients are like those found by Murdaugh & Doyle and by Colton & Lowrie in normals.

Scant reliability of Co/Ct ratio in urea kinetic formulas.

The ratio initial/final urea value is used in urea kinetic formulas. To assess its reliability we employed mass balances and urea clearances to study 15 hemodialysis treatments divided in several parts. The mass balances clearly indicated urea disequilibrium. In the first phases of dialysis, urea extraction, measured by dialysate collection, was lower than the corresponding change in urea pool, whereas in the later phases the opposite occurred. On account of this lack of equilibrium, clearances bases on the Co/Ct ratio (K2) are less reliable than standard clearances derived from total dialysate collection (K1): in the first quarter of dialysis, K2 is greater than K1 (p less than 0.01), while in the 3rd and 4th quarters it is lower. The comparison of clearances in a cumulative way showed a significant fall in K2 (p less than 0.01) while K1 remained stable. From a practical point of view, aberrations induced by non monocompartmental urea behaviour are negligible, and do not invalidate the usefulness of the single-pool Gotch model in clinical practice. However, at least in experimental work, the limits of urea kinetic formulas must be taken into account.

Deficiency 10p. Report of a case and exclusion mapping of the hexokinase 1 locus to band 10p11.2.

A patient deficient for most of the short arm of one chromosome 10 is described. The clinical picture is similar to those of other published cases but includes agenesis of olfactory bulbs, an uncommon finding, already noted in few 10p- patients. The normal levels of hexokinase 1 found in the fibroblasts of the patient allow a more precise localization of the gene at band 10p11.2. The results obtained for inorganic pyrophosphatase confirm the data available from two other cases.