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Biomedical subjects

S Chiaramonte

Publications and source records attributed to S Chiaramonte.

At least 55 records · Page 3Linked to original sources
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↗
PubMed1984

The role of neurotransmitters in the genesis of uremic encephalopathy.

To classify the influence of neurotransmitters in the genesis of uremic encephalopathy we studied cerebrospinal fluid (CSF) and plasma (P) amino acid (AA) concentration, in patients undergoing various dialytic treatments (hemodialysis = HD, intermittent and continuous peritoneal dialysis = IPD and CAPD). HD causes a significant decrease in CSF/P ratios of branched chain AA (BCAA) and a significant increase in CSF Glycine/Valine ratio, suggesting an augmented brain uptake of Glycine at detriment of Valine. In IPD the general trend of Aromatic AA/BCAA ratio suggests a preferential transport of Aromatic AA through the blood brain barrier. The differences between IPD and HD are confirmed by data concerning metabolites of Serotonin and Dopamine: CSF concentrations of 5- Hydroxyindoleacetic acid and Homovanillic acid are low in HD but high in IPD. So, a reduced (in HD) and an increased (in IPD) activity of monoamine systems could be at the basis of some neurological disturbances appearing in uremia.

Adolescent↗
PubMed1982

Changes of cerebral density in dialyzed patients.

CT studies were made on 38 patients receiving different dialytic treatment, 10 patients with chronic renal failure not yet dialyzed, and 15 healthy subjects. No morphological modifications were observed. On the contrary, significant changes of density were demonstrated after a dialysis session in the population treated intermittently. In these patients the density values were similar to those registered in the controls 1-6 h after a dialysis session. End stage renal failure and CAPD patients always had normal density values. Therefore cerebral density changes are caused only by the intermittent dialytic treatment.

Absorptiometry, Photon↗
PubMed1982

Studies on brain density in hemodialysis and peritoneal dialysis.

30 patients on hemodialysis or peritoneal dialysis have been investigated by computerized tomographic (CT) scan. To evaluate possible cerebral alterations induced by dialysis, CT examinations were carried out before, immediately after and 6 h after the end of dialysis with an Evaluskop, which provides an objective precise evaluation of even slight variations in brain density. No morphological variations were noted after dialysis, while the brain density fell significantly during and after the treatment. A decrease in density was not observed in normal subjects or in patients on continuous peritoneal dialysis. The changes in the densitometric values of brain tissue suggest that there is a postdialysis gain in cerebral water linked to the intermittent treatment. CT may represent a simple reliable method for studying uremic encephalopathy and investigating the pathogenesis of the dialysis disequilibrium syndrome.

Adolescent↗
PubMed1982

Anatomical bases of peritoneal permeability: a reappraisal. Anatomy of peritoneum.

The peritoneal membrane consists of flat mesothelial cells linked together with digitations and containing vesiculae with pinocytic capacity, of endothelial cells (containing Weibel-Palade's bodies and vesiculae) and of an interstitial tissue consisting of a network of watery channels. The cellular structures of mesothelium and endothelium are characterized by tight and gap junctions or perhaps by macular junctions. The visceral peritoneum shows a prevalence of gap junctions, the pericysic veins contain only tight junctions while both types can be found in the arterioles. Two different ways for solute transport are theoretically possible: the vesicles of plasmalemma (via pinocytosis) and the junctions (via size-sieving effect). Studies with tracers did not furnish unequivocal data on this problem and did not clarify if these structures could be the equivalent of the pores of the Landis-Pappenheimer's theory. The studies of Karnowsky and Simionescu, using tracers, have in fact given opposite results.

Animals↗
PubMed1982

Pharmacokinetics of intravenous and intraperitoneal cefuroxime during peritoneal dialysis.

We investigated the pharmacokinetics of cefuroxime sodium, a new parenteral beta-lactam antibiotic, in 15 patients with stable chronic renal failure during intermittent peritoneal dialysis (IPD). Eight patients were administered 1 g cefuroxime as an intravenous bolus 1 h before the start of dialysis. Mean plasma levels of cefuroxime fell from 80 mcg/ml at 1 h to 40 mcg/ml at 6-8 h. At 24 h, concentrations were higher than 20 mcg/ml. In peritoneal fluid cefuroxime reached 16.7 mcg/ml at 1 h and 7.55 mcg/ml at 6 h. Seven patients received cefuroxime added to the dialysis solution at a dose of 2.5 g/10 liters. After 6 h of dialysis, cefuroxime reached plasma levels of 60 mcg/ml; after 24 h, concentrations were 37.5 mcg/ml. These results demonstrate that cefuroxime, administered by the i.v. route, easily diffuses from blood to peritoneal fluid and, from peritoneal fluid to blood when added to the dialysis solution. In both cases concentrations reached by cefuroxime are sufficient to treat peritoneal infections associated with peritoneal dialysis.

Adult↗