PubMed Health⌕ Search

Biomedical subjects

R Gervasio

Publications and source records attributed to R Gervasio.

9 recordsLinked to original sources
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↗
PubMed1991

In vivo solute elimination of paired filtration dialysis.

Paired filtration dialysis (PFD) is a new dialysis strategy whereby a hemofilter and a hemodialyzer are coupled in series. It has been assumed that this approach allows a better solute elimination than conventional hemodialysis (HD), allowing a shortening of dialysis time. To evaluate this hypothesis, solute elimination with PFD either with 0.4 m2 polysulphone (PS) and 1.36 m2 cuprophan (CU) 3x3 h/wk, or with 0.4 m2 PS and 1.06 m2 CU 3x4 h/wk, was compared to HD with 1.36 m2 CU, 3x4 hours weekly in the same patients. During PFD, 10L were ultrafiltered and substituted by saline. Overall extraction of UV absorbing solutes (MW less than 10,000 Dalton), and extraction of individual solutes identified by high performance liquid chromatography (HPLC) were compared as well as urea kinetics. For PFD 3x3 h overall extraction of UV-absorbing compounds and of hippuric acid was significantly higher than for HD 3x4 h (p less than 0.05). Overall extraction of UV-absorbing compounds and of all but one individual compound under study was markedly higher for PFD 3x4 h vs conventional HD 3x4 h (p less than 0.01), in spite of a higher diffusive area with the latter technique. No differences in urea kinetics were observed for the 3 strategies. It is concluded that solute extraction during PFD is higher than during HD, if the treatment time is the same. Even if treatment is shortened to 3x3 h weekly, solute extraction with PFD is at least as efficient as with HD.

Biocompatible Materials↗
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

[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↗