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Biomedical subjects

G La Greca

Publications and source records attributed to G La Greca.

At least 73 records · Page 4Linked to original sources
PubMed1996

Acid-base balance with different CAPD solutions.

Our objective is to investigate transperitoneal buffer fluxes with solution containing lactate and bicarbonate, and to compare the final effect on body base balance of the two solutions. One hundred and four exchanges, using different dwell times, were performed in 52 stable continuous ambulatory peritoneal dialysis (CAPD) patients. Dialysate effluent lactate and bicarbonate and volumes were measured. Net dialytic base gain was calculated. Patients' acid-base status and plasma lactate were determined. In lactate-buffer CAPD solution, lactate concentration in dialysate effluent inversely correlated with length of dwell time, but did not correlate with plasma lactate concentration and net ultrafiltration. Bicarbonate concentration in dialysate effluent correlated with plasma bicarbonate and dwell time but not with ultrafiltration. The arithmetic sum of the lactate gain and bicarbonate loss yielded the net dialytic base gain. Ultrafiltration was the most important factor affecting net dialytic base gain. A previous study demonstrated that in patients using a bicarbonate-buffered solution the net bicarbonate gain is a function of dwell time, ultrafiltration, and plasma bicarbonate. By combining the predicted data of the dialytic base gain with the calculated metabolic acid production, an approximate body base balance could be obtained with both lactate- and bicarbonate-buffered CAPD solutions. The body base balance in CAPD patients is self-regulated by the feedback between plasma bicarbonate concentration and dialytic base gain. The level of plasma bicarbonate is determined by the dialytic base gain and the metabolic acid production. This can explain the large interpatient variability in acid-base correction. Bicarbonate-buffered CAPD solution is equal to lactate solution in correcting acid-base disorders of CAPD patients.

Acid-Base Equilibrium↗
PubMed1995

Retroperitoneal abscesses--rare causes and atypical manifestations: report of two cases.

Retroperitoneal space abscesses are a life-threatening illness which is difficult to diagnose and treat because of both their rarity and insidious clinical manifestations. The insidious development of this illness is a challenge for all medical and surgical subspecialists. The discovery of the real source of the infection is very important but not always possible, and knowledge of the anatomy and borders of the retroperitoneal space is helpful in understanding all such atypical cases and for establishing a definitive treatment. Two cases are reported that are both characterized by rare causes, uncommon development, and atypical manifestation. The normally undefined inferior borders of some parts of the retroperitoneal space or previous retroperitoneal surgery could have been the cause of the abnormal and misleading development of the abscesses. Chronically infected organs can be the true origin of this abscess, and their discovery in a nonemergency situation is mandatory for complete surgical treatment. These cases show that knowledge of the anatomy of the retroperitoneal space is important to establish the suspicion of an abscess, to understand its manifestations, which are sometimes caused by a rare pathophysiology, and to initiate appropriate treatment.

Abdominal Abscess↗
PubMed1995

On-line urea monitoring: a further step towards adequate dialysis prescription and delivery.

The aim of this study is to present a clinical experience carried out with a new device designed to measure on-line Urea Nitrogen concentration in the effluent dialysate. The Biostat 1000 Urea Monitor (Baxter Healthcare, Dirfield, Ill, USA) was utilized in the present study. The monitor is based on the principle that multiple urea measurements in the dialysate effluent from the dialyzer, permit to built a double exponential regression leading to the urea kinetic parameters of the dialysis session. Data obtained with the Urea Monitor were, in the present study, compared with those obtained by direct measurements carried out in blood and dialysate and by the collection of the whole amount of spent dialysate. The monitor provided an accurate value of predialysis BUN without any blood drawing. Urea kinetics were established from multiple dialysate measurements and no blood drawing was necessary. The double pool kinetics were taken into account and Kt/V, PCR and SRI% obtained were comparable to those obtained from direct measurement. Since a projected value of Kt/V can be obtained, the monitor could represent a potential source of information to detect possible filter and machine dysfunction, as well as high rate of recirculation.

Adult↗
PubMed1994

Assessment of adequacy in peritoneal dialysis.

Adequacy of peritoneal dialysis has been less well studied than that of hemodialysis. Fractional urea removal, total creatinine removal, and various indices have been proposed to reflect or predict patient morbidity and mortality. No prospective study has been published in this regard. To evaluate this area further, in addition to reviewing selected literature, 45 continuous ambulatory peritoneal dialysis (CAPD) patients were recruited in two dialysis centers for a prospective study on treatment adequacy. Patients were well rehabilitated and had no peritonitis or hospitalization in the 6 months before the study. Urea and creatinine kinetics were analyzed, as were dietary intake and fluid balance. The weekly Kt/V, calculated to include peritoneal and residual renal clearance (KprT/V), averaged 1.77 with a Kt/V hemodialysis equivalent of 0.59. Patients with residual renal function (58% of the studied population) had an average residual renal clearance of 3.42 mL/min, and had lower steady-state concentrations of urea nitrogen and creatinine in the plasma than patients with no residual renal function. As a consequence, a lower percent excretion of urea and creatinine in the peritoneal fluid was observed in the former patients compared with the latter, where the peritoneal route was the only one for solute excretion. The concentration profiles in blood appear to be the critical factor in achieving the final target of the treatment, ie, the excretion of the overall amount of waste products derived from protein and other metabolic pathways. The constant blood levels in CAPD explain why such a low Kt/V can be adequate whereas, in hemodialysis, a higher Kt/V is required.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

Ultrafiltration and clearance studies in human isolated peritoneal vascular loops.

Eight samples of human peritoneal tissue were obtained from patients undergoing hemicholectomy for cancer. An artery and a vein were cannulated and perfused with blood in vitro with a special circuit able to provide different perfusion pressures. Ultrafiltration and clearance studies were performed in these samples. Both ultrafiltration and small-solute clearances linearly correlated with the blood flow, demonstrating a strong dependence on this parameter. The peritoneal capillary showed a typical filtration pressure equilibrium with a constant filtration fraction at different blood flows. The results suggest that the blood flow may be a factor limiting the efficiency of peritoneal dialysis both in terms of mass transfer coefficients and maximal ultrafiltration rates.

Blood↗
PubMed1994

Double pass dialysis: a new method of renal replacement in patients with malfunctioning vascular access.

Several patients undergoing chronic renal replacement therapy present problems related to their vascular access. Low blood flows and high rates of recirculation are common in such patients in which, for this reason, it becomes difficult to apply highly efficient techniques or techniques where diffusion and convection are combined as in hemodiafiltration. In these patients we studied the possibility of partially recirculating the blood in the extracorporeal circuit in order to increase the flow rate per single hollow fiber; we defined our system "double pass dialysis". We evaluated the system's efficiency in 12 patients during 24 dialysis sessions: 12 high flux dialysis sessions (without reinfusion) and 12 hemodiafiltration sessions (9 liters reinfusion). Different surfaces of polyacrylonitrile dialyzers were utilized (1.3-1.7-2.1 sqm) at 250 and 350 ml/min of blood flow with or without 100 ml/min of recirculation. During each dialysis session blood and dialysate samples were taken in order to calculate BUN, Creatinine, Phosphate and Inuline clearances from both the blood and dialysate side. The clearances of low molecular weight solutes were not really influenced by the artificial increase of the blood flow, but on the other hand, the clearances of higher molecular weight solutes increased from 10 to 30% during both high flux dialysis and hemodiafiltration with recirculation. This increase was evident mostly in hemodiafiltration suggesting that the cleaning effect on the membrane has a positive impact on the permeability. The good clinical results obtained with the double pass dialysis show that the system is safe and reliable and may become a valid support in critical situations in order to reach adequate dialysis treatment.

Adult↗
PubMed1993

Multimeric pattern of plasma and platelet von Willebrand factor is normal in uremic patients.

Several studies have reported increased von Willebrand factor (vWF) levels in plasma of uremic patients, with a normal multimeric pattern. Two recent studies, however, have shown a reduction of the larger multimers of plasma vWF and one has also found low levels of platelet vWF in uremic patients with prolonged bleeding time (BT). We have measured plasma and platelet vWF and analyzed its multimeric pattern in 20 uremic patients, 11 with a prolonged BT and 9 with a normal BT. For Plasma vWF, no difference for vWF:Ag, RiCof, and ristocetin-induced platelet agglutination was found between the two groups with normal and prolonged BT. The multimeric pattern of plasma vWF, as evaluated by densitometric scanning of the electrophoretic gels, was normal in both groups. For platelet vWF, vWF:Ag and RiCof content was similar in the two groups. The multimeric pattern was indistinguishable from that of normal platelets. In conclusion, our study does not confirm the presence of a structural defect of plasma vWF and the reduction of platelet vWF content in uremia.

Adult↗
PubMed1993

Technical and clinical evaluation of a new asymmetric polysulfone membrane (Biosulfane).

First generation asymmetric polysulfone membranes had high hydraulic permeability (kf = 40 ml/h/mmHg/sqm) but a low diffusive permeability due to the hydrophobic nature and wall thickness of 75-100 microns. We have tested a new polysulfone membrane with a wall thickness of 40 microns in a series of in vitro and in vivo dialysis session experiments. The new "Biosulfane" membrane presented a Kf of 45.8 with constant performance up to 240 mins. The koA was 760 and the clearance value at 350 ml/min of Qb in hemodiafiltration was 255 ml/min for urea, 210 for creatinine, 225 for phosphate, 76 for inulin. In high flux dialysis the clearances were similar except for inulin which was 32% lower due to the lower convection amount. Beta-2 microglobulin clearance was 22 ml/min in high flux dialysis and 37 in hemodiafiltration. Solute sieving coefficients were close to 1 for the majority of the studied solutes in a wide range of molecular weights and slight variations were observed for charged solutes due to Donnan's effect. The sieving for Inulin was 0.96 while that for Beta-2 microglobulin was not measurable due to a large molecule adsorption on the inner structure of the fibres. The good performances of this membrane are probably due to reduced wall thickness and a consequent improvement in diffusive permeability to small size solutes.

Blood Urea Nitrogen↗
PubMed1993

Short-term clinical study with bicarbonate-containing peritoneal dialysis solution.

OBJECTIVE: The evaluation of the efficacy, adequacy, clinical tolerance, and safety of a new bicarbonate continuous ambulatory peritoneal dialysis (CAPD) solution. DESIGN AND PATIENTS: A 6-week cross-over clinical study in 6 stable CAPD patients was performed. After a control period (2 weeks) with a standard CAPD solution (lactate, 35 mmol/L), a two-chamber bag containing 34 mmol/L of bicarbonate was used for 4 weeks. A breakable valve divided the two chambers, one containing bicarbonate and the other calcium. The two solutions were mixed just before use, thus avoiding the calcium and magnesium carbonate precipitation. RESULTS: No differences between control and study periods were found for blood urea nitrogen, creatinine, total proteins, albumin, total and ionized calcium, phosphate, sodium, potassium, chlorine, and hemoglobin. Blood bicarbonate significantly increased from 21.25 +/- 2.02 to 23.36 +/- 1.15 (p < 0.05) during the study. The peritoneal equilibration tests for urea nitrogen, creatinine, proteins, sodium, potassium, and glucose were slightly reduced during bicarbonate dialysate, but this effect was compensated for by a slight increase of ultrafiltration, thus keeping peritoneal clearances constant. Residual renal function did not change during the study. No side effects occurred during the bicarbonate period. CONCLUSION: A CAPD bicarbonate solution is effective in uremic acidosis correction, does not affect dialysis adequacy, is safe, and well tolerated.

Adult↗
PubMed1993

[Thrombopenia after liver transplantation].

Thrombocytopenia (TP) is a common finding after liver transplantation and is often multifactorially induced. In 31 of 33 liver transplant recipients (operated between 1986 and 1991 at our institution) TP was observed but only in 4 the nadir of the platelet count was less than 20,000/mm3. Highly significant influence in the severity of postoperative TP as well as on the recovery time (defined as the first day with a platelet count higher than 100,000/mm3) was found for a preexisting TP and for the intraoperative need for blood transfusions. 8/33 patients had a concomitant splenectomy but no effect on platelet nadir nor on the recovery time could be detected. In our series we could not find any platelet related factor with a significant impact on patient survival. In one patient severe TP was induced by a CMV-related hematophagic histiocytosis fully regredient with antiviral therapy. Another patient with AB0 incompatible graft had a severe TP induced by graft versus host disease.

Adult↗
PubMed1992

Total gastrectomy: nutritional status after different reconstruction techniques. An experimental study.

The authors report their experimental studies on early nutritional changes in 30 gastrectomized rats where intestinal continuity was restored by three different reconstruction methods, i.e., exclusion of the duodenum from alimentary transit (Sweet-Allen method), or duodenal recanalization (Longmire method) or double duodenal and jejunal recanalization (Moricca method). Ten sham operated rats were used as controls. Results showed that the group of rats which underwent Longmire's reconstruction presented better nutritional parameters (body weight gain, daily food intake, feeding efficiency, albuminemia) than the Moricca and Sweet-Allen reconstruction groups. These results became statistically significant when follow up was extended to 18 months by using an actuarial method. However, perioperative mortality rate was highest in the Longmire reconstruction group.

Anastomosis, Surgical↗