The prediction of single-frequency BIA variables from individual characteristics.

To define whether reference values for bioimpedance analysis (BIA) can be predicted in healthy individuals, individual characteristics and BIA variables (resistance index=height(2)/parallel resistance and reactance index= height(2)/parallel reactance) were evaluated in non-obese healthy individuals: 863 men and 769 women with an age range 20-70 years and body mass index (BMI) 19.0-29.9 kg/m(2). The following predictive equations were obtained using multiple regression analysis:Resistance index (cm(2)/ohm)Males 21.06 + 0.087xage + 1.091xweight -1.801xBMI,Females 20.35 + 0.037xage + 0.878xweight - 1.343xBMIReactance index (cm(2)/ohm)Males 0.57 + 0.117xweight - 0.096xBMIFemales 1.42 + 0.078xweight - 0.075xBMIIn conclusion, reference BIA values seem to be reasonably predicted based on individual characteristics.

Factors affecting nPCR in hemodialysed patients.

The determination of dialysis adequacy is difficult and definitions are in a state of flux (Lindsay). In fact, after fifteen years from the introduction of urea kinetics into clinical practice, nephrologists still do not agree on recognizing the real utility of it. Gotch and Sargent in their mechanistic analysis of the NCDS indicated that the dose of small molecules removal could be defined by Kt/V urea. The results of the NCDS were depicted in a three-variable plot in which six domains could be seen. Several reports have documented malnutrition as being frequently present in patients on maintenance hemodialysis. It is generally accepted that a suboptimal nutritional status is associated with an increased morbidity and may adversely affect rehabilitation and the quality of life. In 1989 Lindsay et al showed that low levels of Kt/V corresponded with low levels of nPCR and found a direct correlation between the two parameters. On this basis, they suggested the hypothesis of nPCR dependence on Kt/V. The Authors showed a good correlation (r = 0.73) between nPCR and Kt/V in 55 patients. This work aims to evaluate the correlation between Kt/V and nPCR, real age and dialytic age in a dialytic population in Southern Italy, during a long period of observation (six years, follow up 2,692 months). One hundred and thirty-four patients were studied in six years of observation. Follow up: 2,692 months. Twenty-six patients died during the observation period. The simple regression analysis of nPCR vs. Kt/V, real age and dialytic age was performed in 63 anuric patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Concentration polarization phenomenon in new and re-used RP610 hemofilters during post-dilutional hemofiltration.

RP610 hemofilters have been used up to five times in post-dilutional hemofiltration. Clearance studies were performed "in vivo" (creatinine and phosphate) and "in vitro" (Cr51 EDTA, I131 Hypaque, Co57 vitamin B12, H3 Inulin, C14 Dextran, I125 Albumin,) in new hemofilters and in those re-used once and five times. Hydraulic permeability and rejection coefficients, for the six markers different molecular weight, were also measured. Our preliminary results show that repeated cleansing with Amuchina does not alter the characteristics of RP610 hemofilters. A scintigraphic method is suggested for visualizing possible changes in polarized areas between new and re-used hemofilters.

[Traditional ultrasonography, directional Doppler power, and levovist in the morphological and functional evaluation of single kidney]. / Ecografia tradizionale, power Doppler direzionale e Levovist nello screening morfofunzionale del monorene.

Either the color and the power Doppler have given important information on renal haemodynamics, but these methods are limited. The power directional Doppler (pdD) surpasses such limits; again, administration of Levovist increases the intensity of vascular signal. The aim of this study is the evaluation, in subjects with a solitary kidney, but without evident nephropathies, the morphology, the cortical vascularization and the functional status of the kidney. We studied 21 patients divided into three groups. Group A: subjects with normal renal function; group B: patients with caliceal and pielic dilation; group C: patient with chronic renal failure (CRF). In all subjects, a pdD was effected. Only in three patients it was necessary to administer Levovist, in order to emphasize the parenchymal vascularization. The A group subjects, on echographic B-mode examination, presented a normal morphology and volume of the kidney; on pdD exam, a regular intense and homogeneous parenchymal vascularization, with resistance index (RI) = 0.53 divided by 0.66. In B group, pdD showed an irregular vascularization, with RI > 0.7; also the glomerular filtration rate (GFR) was reduced (70 ml/min). In C group, at the pdD it was relevant a reduced and irregular vascularization in whole renal tissue. If possible, the echographic B-mode examination must be completed with the pdD, with or without Levovist, in order to identify unknown renal pathologies, moreover in subjects with a single kidney.

[Daily nutrient intake in hemodialysis]. / Variabilità dell'introito giornaliero di nutrienti nei pazienti emodializzati.

BACKGROUND: Although there is a higher nutrient requirement, food intake in haemodialysis patients is often inadequate. Protein nitrogen appearance (PNA) indirectly estimates the mean protein intake during the short interdialysis period, but it does not measure the daily nutrient intake, which is generally unknown. We carried out a longitudinal study aimed at estimating the daily nutrient intake and its relationship with the nutritional status of haemodialysis patients. METHODS: We selected 28 haemodialysis patients with adequate nutritional status and no evidence of risk-factor for malnutrition. Patients were treated with biocompatible membranes, low-flux and high bicarbonate dialysis, Kt/V > 1.2, PNA > 1.1 g/kg/day and erythropoietin. We measured every four months daily PNA, protein and calorie intake (DPI, DCI) as well as weight gain (WG) during an entire week for one-year. The nutritional status was assessed by biochemical and BIA markers. RESULTS: Twenty seven subjects (8 F, 19 M; age 57.1 +- 2.7 yeas; dialysis age 105 +- 13 months) completed the trial. The mean interdialytic PNA did not change in both long- and short-interdialysis periods, resulting in the "normal" range (> 1.1 g/kg/day); however, daily levels of protein and calorie intake were significantly reduced on the third day during the long interdialysis interval. Eight patients showed time-averaged values of DPI and DCI lower than 0.8 g/kg/day and 25 Kcal/kg/day, respectively, on the third day (LOW group), values that were associated with similar changes in WG. Such a highly reduced nutrient intake during the third interdialysis day was associated with a normal PNA value (1.23 +- 0.05 g/kg/day vs 1.30 +- 0.06 in CON, NS) when measured during the short interdialysis period (S), just as it is in clinical practice; in contrast, when the PNA value was measured during the long interdialysis period it was found to be significantly reduced (1.07 +- 0.08 g/kg/day vs 1.37 +- 0.06 in CON, p < 0.05 and vs S, p < 0.05). During the study, the body weight progressively decreased from 68.0 +- 5.5 to 65.8 +- 5.9 kg (p < 0.05) in the LOW group, due to the decrease in lean body mass, as suggested by the reduction in serum creatinine (9.2 +- 1.1 vs 8.1 +- 0.7 mg/dL, p < 0.05), creatinine generation (835 +- 155 vs 723 +- 106 mg/die, p < 0.05) and serum albumin (3.96 +- 0.07 vs 3.66 +- 0.06 g/dL, p < 0.05). Moreover, reactance and phase angle declined in the LOW group (from 54 +- 4 to 44 +- 3 ohms, p < 0.05 and 5.5 +- 0.3 to 4.5 +- 0.3 degrees, p < 0.05, respectively). At the end of the study the nutritional status in the LOW group was reduced as compared to the CON group. CONCLUSIONS: In stable, well-nourished haemodialysis patients, in absence of known risk factors for malnutrition, the daily nutrient intake is variable and progressively reduce during the interdialytic interval. The measurement of interdialytic PNA, as is done in clinical practice, does not enable the discovery of such abnormal eating behaviour; the low daily nutrient intake, on the contrary, can be evidenced by the daily measurement of either PNA or weight gain, and it can also be inferred by the reduced PNA during the long interdialytic period. Finally, the persistent reduction in nutrient intake below the threshold of 0.8 g/kg/day of proteins and 25 Kcal/kg/day one day a week, is capable of inducing body protein wasting and moderate impairment of the nutritional status.

[Usefulness of directional power Doppler sonography in the ultrasound-guided percutaneous native kidney biopsy]. / Utilita' dell'Eco Power Doppler direzionale nella biopsia transcutanea su rene nativo.

BACKGROUND: The study was aimed to analyze the pattern of bleeding throughout the kidney tissue after renal biopsy and evaluate its relationship with the onset of renal biopsy side effects by using directional power-Doppler sonography. PATIENTS: Eighty-five consecutive subjects with clinical evidence of renal disease underwent to percutaneous renal biopsy using directional power Doppler sonography. In each patient, the pattern of kidney hemorrhage immediately after the renal biopsy was evaluated. RESULTS: Fifty-seven patients, representing 67% of all biopsies performed, evidenced renal bleeding lasting 5.3+/-5.7 min; fifty-five patients, representing 65% of all biopsies, developed a post biopsy hematoma (x = 2.9+/-2.0 cm); 36% of patients developed a perirenal hematoma (x = 1.8+/-2.1 cm). A subcapsular hematoma was experienced by 45% of patients (x = 2.7+/-1.1 cm); 16% of these patients had a combined perirenal-subcapsular hematoma; 5% of hematomas were larger than 5 cm. Hematoma dimensions were related to the length of bleeding (r = 0.6331; p < 0.0001). Hemoglobin and hematocrit levels significantly reduced from 12.7+/-2.3 g/dL to 11.7+/-2.3 g/dL (-7%, p < 0.0001) and 37.6+/-6.5% to 35.4+/-6.5% (-6%, p < 0.0001) respectively, and such variations were related to the hematoma size (Delta Hb: r = -0.5171; p < 0.0001; Delta Htc: r = -0.3465; p < 0.0001). CONCLUSIONS: This study demonstrates that directional power Doppler sonography allows medical personnel to clearly evidence all renal biopsy-related side effects and identify, through the evaluation of renal bleeding immediately after the kidney biopsy, those patients who will develop renal hematomas.

A new semiautomated apparatus for hemofiltration.

A new semiautomated apparatus for hemofiltration has been described. It is a postdilutional hemofiltration system that utilizes the RP-610 dialyzer and is made of standard lines used for hemodialysis, a blood pump and two precise volumetric pumps, Logeais-TEC model, for the ultrafiltrate and for the substitution fluid. The ultrafiltrate compartment of the hemofilter is connected to a manometer for detecting positive or negative pressure. The transmembrane pressure TmP is given only by the pressure on the blood side that is regulated by the screw clamp in the venous line. Once started the whole system may be regulated by this screw clamp in order to maintain zero pressure in the ultrafiltrate compartment, provided that ultrafiltration rate does not exceed 65 ml/min. This system is sufficiently accurate to replace bed scales or any other gravimetric device.

Bioelectrical impedance measurement: errors and artifacts.

Bioelectrical impedance analysis (BIA) allows simple noninvasive estimation of body water, and it could potentially be a very useful technique for clinical monitoring and study of abnormalities of body water. It has been shown that the total body impedance is dominated by the arm (46%) and leg (44%). The trunk, which represents an average of 46% of the body weight, accounts for only 10% of the total impedance. The objective of the current study was to determine the errors in prediction of body composition from BIA when applied to dialysis patients with measurement on the nondominant arm, postural changes, muscular contractions or cramps, monolateral lymphoedema, arteriovenous fistula, central venous catheter, or vascular graft. We studied 20 healthy subjects, 20 uremics on chronic hemodialysis, 3 uremics with fever (body temperature >38.5 degrees C), 3 uremics with cramps, 3 patients with monolateral lymphoedema of an arm, and 3 patients with a prosthetic fistula on an arm. The results of our study show different values of total body water (TBW) derived by BIA measurements effected on supine or standing position (percentage rate variation = 1.1% to 1.6%), or effected during fever (6%), during cramps (-0.73%), with lymphoedema (25%), or in presence of a native arteriovenous fistula, a catheter in a central vein, or a graft (between -24% and +4%). We concluded that a significant error may occur in the measurement of body composition from whole body BIA when performed in the reported cases.

Fetal proteins and chronic treatment with low-dose erythropoietin.

The potential stimulating effect of erythropoietin on the production of fetal proteins (FPs) has not been explored in human subjects. Therefore, the plasma levels of fetal fibrinogen (FF), carcinoembriogenic antigen (CEA), alpha-fetoprotein (AFP), and fetal hemoglobin (HbF) were measured in 12 uremic hemodialyzed patients before the first administration and after 1, 2, and 3 months of low-dose erythropoietin (r-Hu-EPO; 45 U/kg body wt I.V., thrice weekly). Such a treatment efficaciously increased total hemoglobin (Hb). CEA and AFP increased from 5.8 +/- 1.1 ng/ml and 2.9 +/- 0.9 ng/ml to the final value of 43.2 +/- 3.9 ng/ml and 8.7 +/- 1.1 ng/ml, respectively, in the absence of detectable neoplastic diseases. The levels of FF did not change. HbF levels increased from <3% of Hb to the peak value of 48% at the end of the first month; subsequently, a progressive reduction in HbF was observed. Similar changes were detected in the reticulocyte count (RET). A striking correlation was found between HbF and RET (r = 0.8633, p < 0.0001), indicating that the increment in HbF was dependent on the erythroid activity. In conclusion, this study evidences broader than expected effects of erythropoietin on the synthesis of FP and suggests that (1) r-Hu-EPO markedly increases HbF in a condition of suppressed bone marrow activity, (2) the measurement of the cell proliferation markers CEA and AFP is unreliable during r-Hu-EPO therapy, and (3) the prothrombotic state associated with chronic r-Hu-EPO treatment in patients with uremia cannot be attributed to the presence of FF.

Successful use of central venous catheter as permanent hemodialysis access: 84-month follow-Up in lucania.

Cuffed tunneled venous access catheters are commonly used for temporary and permanent access in hemodialysis (HD) patients. These catheters serve an essential role in providing permanent access in subjects in whom all other access options have been exhausted. The predominant complications are catheter thrombosis, catheter fibrin sheating and infection. The aim of this study was to evaluate long-term survival and complications of permanent venous catheters (PVC) placed for the purpose of HD during the period from January 1992 to December 1998, at the Dialysis Units of Lucania (a southern Italian region). A total of 98 PVC were placed in 88 patients during this period. The catheters used were of three types: (a) 72 VasCath Soft Cell catheters (Bard Instrument Company, Toronto, Ont., Canada); (b) 22 PermCath catheters (Quinton Instrument Company, Seattle, Wash., USA), and (c) 4 Tesio catheters (Bellco SpA, Mirandola, Italy). Survival curves of catheters were calculated using the Kaplan-Meier product-limit estimator. The patient survival was 60% at the 78th month. Actually, 52 patients (27 males, 25 females) are still alive: 15 (26.9%) of these patients have diabetes mellitus and 1 has been transplanted. The actuarial survival rate of PVC was 89% in the whole population studied and 82% in subjects alive after 84 months. Twenty-five patients (28.4%) had PVC as the first reliable vascular access. Long-term complications occurred 27 times (1 episode every 44.81 month/patient) as: breakage (3.1%); thrombosis (10.2%); displacement (2.0%); subcutaneous tunnel bleeding (3.1%); inadequate blood flow (7.1%), and infection (10.2%). In conclusion, our data confirm that PVC might represent an effective long-term blood access route for HD. Again, PVC are getting the access of choice for selected patients (i.e., older subjects with cardiovascular diseases and cancer patients) and are enjoying a dramatic increase in use for subjects who are terrified of repetitive venopuncture.