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Biomedical subjects

S Chiaramonte

Publications and source records attributed to S Chiaramonte.

At least 37 records · Page 2Linked to original sources
PubMed1988

Renal functional reserve in pregnancy.

Creatinine clearance has been evaluated under baseline conditions and after acute protein load in five normal and 29 pregnant women at different stages of pregnancy without evidence of renal disease. After a 3-h period in which creatinine clearance was measured hourly (resting GFR), a meal containing 80 g of proteins was administered and creatinine clearance was measured hourly for 4 h (test GFR). Resting GFR in normal subjects averaged 104 +/- 22.5 ml/min per 1.73 m2, the wide variation being due to different dietary, protein intake (from 0.3 to 1.2 g of protein per kg body weight). In the pregnant women the resting GFR increased progressively from the first month (99.8 +/- 12.8 ml/min per 1.73 m2) to the last month of gestation (149.6 +/- 12.5 ml/min per 1.73 m2). All subjects showed a significant increase of GFR after protein load although the greatest difference between the resting and the test GFR was detected in the first trimester. Inulin clearance was also measured in seven subjects after protein loading to compare creatinine and inulin clearance values. The two clearance values did not differ significantly, showing that creatinine can be safely used as a reliable marker for measuring GFR. Test GFR averaged 163.3 +/- 4.1 ml/min per 1.73 in normal subjects and 163.8 +/- 6.5 ml/min per 1.73 m2 in pregnant women without any relationship with the stage of pregnancy. The identity of test GFR both in normal subjects and in pregnant women suggests that this parameter is likely to be related to the functioning renal mass, and represents the filtration capacity of the kidney.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Chronobiological variations of prolactin (PRL) in chronic renal failure (CRF).

During a 24-hour period, the serum levels of prolactin (PRL) were determined in 89 subjects, including 24 controls and 65 with chronic renal failure (CRF), divided into groups according to sex, age and serum creatinine. In mild CRF, both in males and females, PRL level proved to be higher than controls while its circadian rhythm of secretion disappeared. The MANOVA analysis (multivariate analysis of variance) showed that all 3 considered factors (sex, age, creatinine) have a systematic effect on PRL values, that of creatinine being the most prominent. With the progression of renal failure, the physiological PRL oscillations tended to diminish. In general, increasing creatinine levels progressively shifted the acrophase (that is the time-distance between a given hour and the maximum peak of the function) to the morning, with hemodialysis patients showing acrophases between 12 p.m. and 1 a.m. It is possible that in CRF the PRL feedback system could no longer function.

Adolescent↗
PubMed1988

Technical and clinical evaluation of a new polyamide hollow fiber hemofilter for CAVH.

We carried out an in-vivo and in-vitro evaluation of a new polyamide hollow fiber hemofilter especially designed to operate under conditions of low pressure and low blood flow, such as in continuous arteriovenous hemofiltration (CAVH). The results obtained suggest that this filter is a prototype of a new generation of hemofilters especially designed for CAVH. Its low resistance permits its use even in patients with severe hypotension. The high blood flows achieved at a given pressure reduce the risk of clotting and increase the ultrafiltration rate. When an average ultrafiltration of 20-25 ml/min is achieved in 24 hours CAVH becomes very efficient, and alternative techniques to increase its efficiency are no longer required.

Acute Kidney Injury↗
PubMed1988

Comparison of four different short dialysis techniques.

The goal of shortening dialysis treatment time has stimulated the development of new, highly efficient dialytic strategies. In this study the Authors compared four different short dialysis treatments in terms of efficiency, clinical tolerance, technological investment and costs: 1) Rapid bicarbonate dialysis with 1.5 sq.m. cuprophane membrane; 2) High flux biofiltration with 1.2 sq.m. AN69S hollow fiber membrane; 3) Hemodiafiltration with 1.2-1.9. sq.m. polysulphonic hollow fiber hemodiafilters, and 4) High flux hemodiafiltration with two serial hemodiafilters with AN69s membrane (total 2.4 sq.m.). Hydraulic properties and solute clearances at different blood flows (300-500 ml/min) were tested for each technique. Once the optimal operative level was established three patients were treated with each technique for at least six months. Since BUN clearance averaged 310 ml/min, the treatment duration varied from 120 to 180 min/session with KT/V always higher than 1. The average protein catabolic rate was 0.9 g/kg/24h. Clinical tolerance was generally good, slightly better in treatments with a high convective component. Despite the greater efficiency of treatment No. 4, the technological requirements and costs are such that the others are currently more feasible and acceptable in clinical routine. The study demonstrates that reduction of dialysis treatment time is possible in all centres in a selected population with adequate blood access. Treatment No. 1 can even be performed with standard equipment and cuprophan membranes, while bicarbonate in the dialysate is mandatory. The real limit to shortening treatment time seems to be related to the maximal rate of ultrafiltration achievable in the patient during dialysis.

Adult↗
PubMed1987

Arteriovenous hemodiafiltration associated with continuous arteriovenous hemofiltration: a combined therapy for acute renal failure in the hypercatabolic patient.

To increase the efficiency of continuous arteriovenous hemofiltration (CAVH) in cases of severe catabolism, we used a modified CAVH treatment, called arteriovenous hemodiafiltration (AVHDF), in 4 patients. The transport of solutes was increased by providing the infusion of a counter current flow of urea-free solutions in the UF compartment of a standard CAVH circuit. Patients were treated with standard CAVH and, when a more efficient treatment was required, intermittent daily sessions of AVHDF were performed using the same filter and lines. The urea kinetic study enabled the calculation of the time needed to perform AVHDF, in addition to standard CAVH, to maintain the blood urea nitrogen (BUN) level under control. A dialysate flow rate of 300 ml/min made it possible to increase the urea nitrogen mass transfer rate from 10 to 65 mg/min and the clearance from 10.5 to 37.5 ml/min. The addition of AVHDF to CAVH enabled the control of BUN levels in the 4 patients affected by acute renal failure and a severe catabolic state. The technique is simple, does not require additional devices, and maintains the advantages of CAVH providing a better efficiency in terms of solute removal.

Acute Kidney Injury↗
PubMed1987

Hyperprolactinemia as a marker of neurotransmitter imbalance in uremic population.

Serum prolactin (PRL) levels are elevated in patients with chronic renal failure (CRF) but the mechanisms responsible for these abnormalities are not fully understood. PRL secretion is undoubtedly influenced by many substances, which can be variously altered in uremia: monoamines, endogenous opiates and PTH. Our data suggest that in early renal failure PRL levels are already significantly high and the 24-h pattern of PRL secretion is significantly different from that in controls. PRL derangements could be due in mild renal failure, to unknown factors (GABA?); in severe CRF, to a major change in dopaminergic activity; in hemodialysis (HD), to a low turnover of monoamines, and in peritoneal dialysis (PD) to increased activity of serotoninergic and dopaminergic systems.

Adolescent↗
PubMed1987

Tricarboxylic acid cycle intermediates in chronic renal failure.

In 21 uraemic subjects not yet requiring dialysis, the serum values of citrate, fumarate, oxalacetate and malate were significantly increased, so that the sum of the concentrations of the TCA-cycle intermediates were increased threefold compared to that of 18 control subjects. The replenishment of TCA intermediates could, in theory, occur by several anaplerotic reactions, mainly those catalysed by pyruvate-carboxylase and malic enzyme. The overall pattern detected in uraemic patients is similar to that observed in rat skeletal muscle during exercise, in which increased acetyl CoA has been found.

Adult↗
PubMed1987

Solute and water transport during continuous arteriovenous hemofiltration (CAVH).

The transport mechanisms governing solvent and solute removal during CAVH were elucidated on the basis of in vitro and in vivo observations. Using a typical hemofilter (Diafilter D-20, AMICON), filtration rate rose with inlet blood flow rate until an asymptote was reached at blood flows of approximately 150 ml/min. The onset of the asymptote coincided with transition from a regime controlled by oncotic pressure (filtration pressure equilibrium), to one governed by simple Darcy's law filtration behaviour. Subsequent measurements showed that under clinical conditions, CAVH is generally in the pre-asymptotic regime and operates at filtration pressure equilibrium. These observations offer the theoretical bases for a new design for CAVH hemofilters. As a possible corollary, middle-molecule sieving coefficients were found to be stable with time during CAVH in vivo, whereas in chronic mechanical hemofiltration they declined significantly during clinical treatment. The sieving coefficients, however, were lower in mechanical hemofiltration from the beginning of the session. These observations suggest that the measured sieving coefficient for a membrane is not necessarily a constant directly and solely related to the membrane standard reflection coefficient for a given solute. Concentration polarization and the ultrafiltration rate per unit of surface area may in fact have a major effect on the final concentration of solutes in the ultrafiltrate.

Biological Transport↗
PubMed1986

Treatment of acute renal failure in newborns by continuous arterio-venous hemofiltration.

The treatment of acute renal failure (ARF) in the newborn with hemo- or peritoneal dialysis is technically difficult and may even be contraindicated. As in the adult, continuous arterio-venous hemofiltration (CAVH) may be an alternative therapy. We used CAVH in the treatment of four newborns with ARF of different etiology. Two brachial, one femoral and one umbilical arteries were cannulated as arterial access, while three jugular and one umbilical veins were used as venous return. An Amicon 0.005 m2 Polysulphon Hollow Fiber hemofilter was connected to the patient with shortened pediatric hemodialysis lines. Total blood volume of the extracorporeal circuit was 15 to 22 ml. Before starting the procedure, an initial bolus of heparin was administered to the patient (100 i.u./kg body wt) and a successive continuous heparin administration was provided during the treatment at the rate of 5 to 7 i.u./kg/hr. Hyperalimentation and/or buffer solutions were used as replacement fluids and were administered according to the patient's fluid balance. mean data in the four patients are summarized as follows. The age of the patients ranged from two to 12 days, while the average body weight was about 3 kg. The ultrafiltration rate during the treatment averaged 0.9 ml/min with a plasma flow ranging from 9.8 to 19.6 ml/min. The treatment duration varied from 30 to 86 hrs. The treatment was well tolerated (patients 1 and 2 recovered, and patients 3 and 4 died due to complications unrelated to the treatment). Arterial pressure remained stable during the procedure. Metabolic acidosis, when present, was corrected by increasing the amount of buffer administered. BUN was maintained below 60 mg/dl in three patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Kidney Injury↗
PubMed1986

Buffer kinetics in biofiltration.

A condition of metabolic alkalosis has been generally observed in patients undergoing regular biofiltration (BF). The aim of this study was to assess buffer kinetics during a dialysis session in five patients regularly treated by BF for 10 months (dialyzer Biospal 3000S, Qb 301; Qd 545; UF 36.76 ml/min; dialysate CH3 COO 38 mEq/L; replacement fluid 1000 ml/h with HCO3 100 mEq/L solution). As usually happens using dialyzers with high surface area and permeability, large HCO3 losses (756 +/- 112 mEq) and CH3COO uptakes (677 +/- 152 mEq) were observed. Acetate plasma levels rose to 10.4 mEq/L, a value potentially dangerous to the cardiovascular system. The dialytic buffer gain (acetate uptake + HCO3 administered - HCO3 loss) was high (230 +/- 137 mEq/dialysis) and excessive for patients' needs. It is therefore very important to reduce either the acetate concentration in dialysate or the amount of reinfused bicarbonate. In view of the plasma acetate levels it is preferable to use a dialysis solution containing less acetate.

Acetates↗
PubMed1986

Uremic encephalopathy: an updating.

Uremic encephalopathy (UE) is a clinical syndrome, closely linked to the progression of renal failure. Many approaches can be utilized to diagnose it: EEG changes, somatosensory evoked potentials, choice reaction time test, cerebrospinal fluid (CSF) studies, brain computerized tomography, plasma and CSF amino acid concentration. On the basis of the data available at present, it is possible to postulate that UE could be caused by amino acid derangements (mainly glutamine, glycine, aromatic and branched-chain amino acids) and by the subsequent imbalance of neurotransmitters (mainly GABA, dopamine, serotonin). Disturbances of mental, neurologic, motor and hormonal functions could derive.

Amino Acids↗
PubMed1986

Preliminary technical and clinical evaluation of a new hollow fiber dialyzer with a 5 microns thick cuprophan membrane.

In vitro and in vivo studies were performed on 10 dialyzers with 5 microns thick cuprophan membrane to evaluate hydraulic properties and permeability to solutes. Inlet and outlet pressures of the filter were measured at different blood flows to assess the resistance of the device and the end-to-end pressure drop. Hysolated ultrafiltration was performed to evaluate the spontaneous filtration at increasing blood flows, the ultrafiltration rate at different transmembrane pressures and, finally, the sieving coefficients for solutes. Standard hemodialysis was also performed to study the clearances throughout a 4-h session. During hysolated ultrafiltration the UF rate was increased up to 37 ml/min showing a very high hydraulic permeability of the membrane. The spontaneous filtration rates related to blood flow were quite low. Since the end-to-end pressure drop in the filter was also relatively low at high blood flow we may conclude that the geometry of the device is able to dissociate the influence of blood flow on the hydrostatic pressure inside the filter. This results in a easy modulation of the membrane permeability to water. Sievings were surprisingly high and clearances were stable along the dialysis session (BUN = 196 ml/min, creatinine = 161 ml/min and phosphate = 163 ml/min).

Blood Flow Velocity↗