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Biomedical subjects

P M Ghezzi

Publications and source records attributed to P M Ghezzi.

18 recordsLinked to original sources
PubMed1992

Prevalence of HCV antibodies in a uraemic population undergoing maintenance dialysis therapy and in the staff members of the dialysis unit.

We studied, by both 1st and 2nd generation assay, the prevalence rate of HCVAb in a population of 141 dialysis patients, 37 transplanted patients and 55 staff members. From this study emerges a higher sensitivity of the 2nd generation HCVAb test (15.38 versus 36.79% of positive responses, respectively), and a significant positive correlation between lengths of dialysis period. We have not found a significant difference between HCVAb-positive and -negative patients in relation to the blood transfusions. None of the 21 CAPD patients (home dialysis) resulted positive, even if transfused. Two nurses were positive. In our experience, the environmental factor seems more important. Since the isolation of the positive patients is an effective but not feasible measure, it is necessary to improve the operating management of the hemodialysis sessions, avoiding any contact between patients via material (instrumentation, monitors) and teaching the staff members to use severe preventive standards with all hemodialysis patients.

Cross Infection↗
PubMed1991

Use of the ultrafiltrate obtained in two-chamber (PFD) hemodiafiltration as replacement fluid. Experimental ex vivo and in vitro study.

PFD (Paired Filtration Dialysis) is the only hemodiafiltration (HDF) technique in which the ultrafiltrate (UF) is continuously available not mixed with the dialysate. As with all convective or prevailingly convective techniques, a replacement fluid is necessary in an amount equal to the difference between the UF and the desired weight loss. This replacement fluid (R) must have an adequate electrolytic balance (Na+, Ca++, and buffer), and must be sterile and pyrogen-free. Using an uncoated adsorbent charcoal cartridge, we "regenerated" the UF obtained in PFD, eliminating the small (except for urea, which was later eliminated by diffusion in the dialyzing section of the PFD system) and the medium-to-large molecules (vit B12 and myoglobin in vitro and beta-2-microglobulin (B2m) and (hANP) in vivo), but not the electrolytes and the endogenous bicarbonate, so as to verify its possible use as R. This technique, experimentally performed in 12 patients under HDF treatment with standard PFD, with a total mean UF of 9650 +/- 875 ml and the use of 130 g of uncoated charcoal, produced a solution with the following composition: Na+ 135.4 +/- 2.4 mmol/l, K+ 3.4 +/- 1.23 mmol/l, Ca++ 1.18 +/- 0.14 mmol/l, HCO3- 26.7 +/- 2.3 mmol/l, phosphates 2.88 +/- 0.81 mg/dl, urea 63 +/- 14 mg/dl, creatinine 0.08 +/- 0.02 mg/dl, uric acid 0.05 +/- 0.0 mg/dl, beta-2 microglobulin 0.5 +/- 0.5 mg/l, and hANP 4.15 +/- 5 pg/l.(ABSTRACT TRUNCATED AT 250 WORDS)

Cellulose↗
PubMed1983

Echotomography in arteriovenous fistulae.

We employed Echotomography (by 2.25-5MHz probes) as a quick procedure to measure the vessel diameter at definite points to detect aneurysms and their evolution, to evaluate the arteriovenous fistula (AVF) characteristics, to detect haematoma, thrombi, and collateral vessels. Echotomography is a non-invasive technique which may be performed repetitively even immediately after AVF surgery. It was most valuable in the examination of proximal AVF and internal shunts (autologous venous and bovine carotid grafts). Echotomography has proved to be accurate in studying the initial morphological and functional evaluation and follow-up of AVF.

Arteriovenous Shunt, Surgical↗
PubMed1980

[Kinetics of anticoagulation in hemodialysis. Sequential study of single, intermittent and continuous heparinization].

A sequential real-time study was run to monitor plasma heparin values following three standard dose protocols during 4-hr dialysis, using an enzymatic method. One group of patients was given a single dose of 7000 IU at the commencement of dialysis, a second group 5000 IU at the start and 2500 IU at the end of the third hour, and a third group 2500 IU at the start and 1500 UI/hr for four hours. Plasma levels were checked every hour and ranged from 0.702 IU/ml (+/- 0.069) (start) to 0.290 IU/ml (+/- 0.079) (end) in the first group, 0.552 (+/- 0.116) to 0.312 (+/- 0.09) in the second, and 0.456 (+/- 0.113) to 0.314 (+/- 0.063) in the third. Correlation of heparin levels with coagulation time led to the establishment of an optimal range of 0.2 to 0.6 IU/ml.

Blood Coagulation Tests↗
PubMed1980

["Clinical clearance" and "weekly clearance" of urea in periodical hemodialytic treatment].

Starting from the hypothesis that small molecules are freely diffusible, a simple formula is proposed for the determination of real ureic clearance during dialysis. This automatically allows for all variables (blood flow and flow of the dialysing solution, temperature, physical and/or chemical state of the membrane, level of solute concentration, transmembrane pressure, etc.). On the basis of this formula, a calculation system is also proposed for assessing weekly ureic clearance levels and hence the real efficiency of treatment. This system may also be applied to peritoneal dialysis and permits optimisation of substitutive treatment. It is thus easier to select the best filter and rhythms for each patient.

Humans↗
PubMedDate not supplied

Hemodiafiltration without replacement fluid. An experimental study.

Paired filtration dialysis (PFD) is the only hemodiafiltration (HDF) technique in which the ultrafiltrate is continuously available but not mixed with the dialysate. As is the case during all convective or predominantly convective techniques, use of a replacement fluid is necessary in an amount equal to the difference between the ultrafiltrate and the desired patient weight loss. This replacement fluid must have an adequate electrolytic composition (Na+, Ca++, and buffer), and must be sterile and pyrogen free. Using an uncoated adsorbent charcoal cartridge (130 g), the ultrafiltrate obtained in PFD was regenerated, eliminating both the small (except for urea, glucose, and phosphates) and medium-to-large solutes but not the electrolytes and bicarbonate. This verified the ultrafiltrate's possible use as replacement fluid. This technique experimentally studied during 24 standard PFD sessions, with a total mean ultrafiltrate of 9,950 +/- 860 ml, allowed a replacement solution to be obtained with the following mean +/- SD composition: pH 7.467 +/- 0.122, HCO3- 27.0 +/- 2.12 mmol/L, Na+ 137.4 +/- 2.6 mmol/L, K+ 4.1 +/- 0.83 mmol/L, Ca++ 1.12 +/- 0.19 mmol/L, urea 68.3 +/- 16.2 mg/dl, creatinine 0.08 +/- 0.02 mg/dl, uric acid 0.05 mg/dl, phosphates 2.77 +/- 0.71 mg/dl, beta-2 microglobulin 0.5 +/- 0.4 mg/L, and atrial natriuretic peptide 4.41 +/- 5.6 pg/ml.(ABSTRACT TRUNCATED AT 250 WORDS)

Charcoal↗
PubMedDate not supplied

Continuous pH and HCO3 monitoring during hemodiafiltration without blood sampling.

The correction of acid-base balance during hemodialysis, especially in high-efficiency techniques, could present some problem related to the lack of an adequate monitoring of pH and blood gases. During hemodiafiltration (HDF), performed with the two-chamber technique (paired filtration dialysis, PFD), the ultrafiltrate (Uf) is continuously available, unmixed with the dialysate. Connecting a pH electrode (as Ag/C1Ag) to the Uf circuit, the authors made 40 determinations on 16 different PFD patients, and they correlated the Uf values obtained with those measured on arterial blood with standard methods. The one sample analysis gave a t = 10.145 (p = 0.0), and the linear regression analysis an r = 0.931 (p = 0.0). At 30 min, in 8 PFD patients, the HCO3 values obtained from Uf, pH and transcutaneous PCO2, gave a t = 6.37 (p = 0.0004), and an r = 0.939 (p = 0.00052). In conclusion, during HDF performed with PFD, continuous pH monitoring of the patient is possible without blood sampling. Moreover, correlation with the transcutaneous PCO2 measurement could provide HCO3 values in real time.

Acid-Base Equilibrium↗
PubMedDate not supplied

[Critical evaluation of dialytic adequacy].

At present it is difficult to define the concept of dialysis adequacy correctly. The paper analyses two of the parameters which are commonly used for this purpose: Kt/V and the behaviour of Beta-2 microglobulin, molecular antipodes for the removal of uremic toxins. A critical analysis is made of the validity of methods to calculate the former and the reliability of the latter. Attention is focused on the fact that an evaluation of dialysis adequacy cannot be limited to theoretical observations regarding the removal of solutes, but must also be integrated by the clinical observation of patients and the commencement of support therapy (pharmacological and/or nutritional and/or physical). In this manner, the adequate treatment of the uremic patients is not entrusted solely to the technological component.

Algorithms↗
PubMedDate not supplied

[Hemodiafiltration: choice or necessity in high-efficiency treatment?].

The risks of back-filtration that occur with the use of high hydraulic permeability membranes with haemodialytic techniques in the course of which the difference between forced and necessary ultrafiltration is compensated for by correcting transmembrane pressure in favour of the dialyser compartment. In this way a form of concealed haemodiafiltration is attained in which the replacement fluid is the dialysing solution, annulling, owing to the possible consequences of the transit of bacterial endotoxins into the circulation, all the advantages linked to the use of these membranes. It is concluded by suggesting the implementation of well controlled haemodiafiltration through the careful quali-quantitative evaluation of the replacement fluid.

Endotoxins↗