[20 years' experience with "difficult" vascular access]. / Venti anni di esperienza sugli accessi vascolari "difficili".

The increased survival of patients in dialysis and the gradual increase in the age of uremic patients commencing chronic dialysis raises serious problems for the creation and maintenance of efficient vascular access. In cases in which it is extremely difficult to create arteriovenous fistulas (AVF) using existing upper limb veins, it is possible to resort to vascular grafts, lower limb AVF, central venous catheters or refer the patients for peritoneal dialysis if this method is technically possible. In order to evaluate the incidence of these phenomena in quantitative terms, the authors have made a retrospective analysis of patients undergoing vascular access surgery since the opening of the Dialysis Centre on 1/9/1973 to 30/9/1996. During this period (277 months) a total of 1,037 AVF implant operations were performed (in addition to 65 arteriovenous shunts in the earlier period and 28 permanent central venous catheters in the last 10 years). The survival of AVF grafts was lower than that in natural vessels in 384 patients without clinical risk. In diabetic subjects, those suffering from vascular pathologies, systemic diseases, or aged over 70, the survival of AVF was distinctly lower compared to the group without these risk factors. However, the higher risk group did not show any marked difference in survival between AVF in the patient's own veins and grafts. In only 4 out of 1,037 operations it was impossible to obtain vascular access in the upper limbs (2 patients were referred for peritoneal dialysis and AVF were executed in the thigh in 2 patients). In conclusion, the retrospective analysis of this series leads the authors to affirm that the rational use of natural vascular accesses normally allows a sufficient operating margin; however, in special cases suitable techniques (such as permanent central venous catheter or AVF in the thigh) can enable difficult situations to be resolved as an alternative to peritoneal dialysis.

[14 years' experience with large-surface-area dialyzers]. / Quattordici anni di esperienza con dializzatori ad ampia superficie.

Hemodialysis treatments with large surface area dialyzers were introduced in our dialysis unit since 1974. 129 uremic subjects were treated between September 1974 and August 1988. Age at start of high efficiency therapy ranged between 16 and 72 years; patients survival was: 95.3% at 1 year, 78.3% at 5 years, 65.8% at 10 years. At present 48 subjects are treated with this schedule. The key technical elements for implementation of such program include: high blood flow rates (greater than 300 ml/min), high surface area dialyzers (greater than 1.8 m2), bicarbonate as the buffer source. Traditionally, the rate of ultrafiltration was controlled by monitoring the TMP and the patients body weight, but in some case a preferred approach is the use of an automatic ultrafiltration control system. We conclude that, in a quite large dialysis population, an individualized short dialysis schedule may be safely applied for long time periods.

Morphometric evidence of the trophic effect of L-carnitine on human skeletal muscle.

We investigated the effect of long-term i.v. administration of L-carnitine on human muscle fibers using morphometric parameters. We administered 2g/day L-carnitine to patients undergoing hemodialysis for at least 12 months. At the end of this period a marked increase in serum and muscle carnitine levels was observed in all patients, together with hypertrophy and predominance of type 1 fibers. L-carnitine was withheld for 4 months, during which time serum and muscle levels gradually decreased and no changes were observed in muscle fibers. Subsequent addition of L-carnitine to dialysis fluid for another 4 months stabilized lower levels. At the end of this period reduction of diameter of type 1 fibers was observed. Type 2 fibers remained unchanged. Moreover, type 1 fibers remained predominant in all cases. Hence, we suggest that carnitine has a specific trophic effect on type 1 fibers which are characterized by an oxidative metabolism.

L-carnitine addition to dialysis fluid. A therapeutic alternative for hemodialysis patients.

L-Carnitine has been reported to have beneficial effects in the reduction of serum triglycerides and increases high-density lipoprotein cholesterol in hemodialysis patients. The published reports are, however, equivocal. Paradoxical increases in serum triglycerides following intravenous administration of L-carnitine have been observed. It has been suggested that the paradoxical rise in triglycerides may result from the high doses used and intravenous administration, both of which may cause abnormally high tissue concentrations. In the present study 22 hemodialysis patients were selected. All patients had been treated intravenously with 2 g of L-carnitine administered at the end of dialysis for a minimum of 12 months. Treatment with L-carnitine was then discontinued during a 4-month washout period. The patients were then divided into two equal subgroups and placed on L-carnitine therapy (1 g i.v.) at the end of dialysis for 1 month. Thereafter, L-carnitine was added to the dialysate (2 g in group 1, 4 g in group 2) for 3 months. Serum and muscle carnitine levels were determined throughout the study as were lipid parameters, serum chemistry, and hematology. Muscle biopsies obtained at baseline revealed supranormal levels of carnitine which decreased to normal levels following the 4-month washout period. When therapy with L-carnitine was resumed, intravenous administration or in dialysate, the muscle carnitine levels remained within the normal range. Similarly, serum carnitine was markedly elevated at baseline and decreased to normal during the washout period. When L-carnitine was added to the dialysate, total carnitine was observed to significantly increase in the group receiving 4 g.(ABSTRACT TRUNCATED AT 250 WORDS)

Favorable effects of L-carnitine treatment on hypertriglyceridemia in hemodialysis patients: decisive role of low levels of high-density lipoprotein-cholesterol.

Twenty-nine hemodialyzed patients with hypertriglyceridemia were given L-carnitine (20 mg/kg iv at the end of each dialysis) for 120 days and then placebo for the same duration in order to evaluate the lipid-lowering effects of the metabolite. A dramatic reduction in triglyceride levels was observed only in the group of patients (n = 12) with high basal triglyceride values, low levels of high-density lipoprotein-cholesterol, and with apoprotein A at the lower limit of normal range. During L-carnitine treatment these patients exhibited significantly increased high-density lipoprotein-cholesterol and apoprotein A. No rebound effects were observed. L-Carnitine did not provoke changes in the lipid parameters in the group (n = 17) with high basal triglyceride values, and normal high-density lipoprotein-cholesterol and apoprotein A. Hematocrit values increased in all the 29 patients during L-carnitine treatment. At the end of the experimental protocol, L-carnitine dosage was increased to 60 mg/kg iv (at the end of each dialysis) in four patients of the group of nonresponders and prolonged for 60 days. This produced a considerable reduction in triglyceride levels. The above results suggest that L-carnitine can be effective in the management of hypertriglyceridemia in the hemodialyzed patient especially when low high-density lipoprotein-cholesterol levels are present.

Drug treatment of hypertriglyceridaemia in chronic uraemic patients: preliminary report on D,L-carnitine and thiadenol.

Clofibrate (a very effective lipid-lowering drug) may cause serious muscular damage in uraemic patients, even if used at appropriately low dose. Some authors have reported that D,L-Carnitine and Thiadenol can reduce lipid levels in non uraemic subjects, without adverse effects. In our study D,L-Carnitine and Thiadenol were administered for 3 months to respectively 21 and 15 patients on chronic haemodialysis with hypertriglyceridaemia. With D,L-Carnitine 52% of patients showed lower plasma triglycerides (TG) (-40.6%, p less than 0.002); after Thiadenol 66.6% of patients showed reduced plasma TG concentration (-42.9%, p less than 0.001). No dietary changes were recorded during the study. No major side effects nor biochemical changes were observed. D,L-Carnitine and Thiadenol appear to be less effective, but also less dangerous than Clofibrate in chronic uraemic patients.

RDT with acetate-free bicarbonate buffered dialysis fluid: long-term effects on lipid pattern, acid-base balance and oxygen delivery.

Thirteen uraemic patients with hypertriglyceridaemia were treated for 9 months with acetate-free, bicarbonate containing dialysis fluid. With this treatment more physiological correction of acid-base balance and better tissue oxygenation were obtained. This fact can explain the better tolerance to treatment we have seen. In 9 of these patients triglyceride levels fell significantly on bicarbonate treatment; they shifted back to higher values after return to acetate dialysis. No changes were found in the other 4 patients.

Antral G- and D-cell counts in chronic renal failure.

Antral somatostatin- and gastrin-producing cells (D and G cells) were studied in a group of patients with chronic renal failure (CRF) in comparison with a control group. Gastric acid secretion and serum gastrin, phosphate, and parathormone (PTH) levels were also evaluated in every patient. The group with CRF showed a mild increase both in G- and in D-cell denisty. In this group serum phosphate and PTH levels were higher than normal, showing hyperparathyroidism in every patient. A direct correlation was found between G-cell density and parathyroid function in patients with CRF. Hyperparathyroidism, therefore, seems to play a role in the mechanism of increased serum gastrin levels in CRF.

[Acute hyperparathyroidism. Emergency surgical operation in a case of hypercalcemic coma]. / Iperparatiroidismo acuto. Intervento chirurgico d'urgenza in un caso di coma ipercalcemico

A case of acute hyperparathyroidism complicated by oliguric renal failure successfully resolved only after surgical removal of a parathyroid adenoma is reported. The need for early diagnosis of this rare condition is stressed and the commonest and most recent techniques for investigating primary hyperparathyroidism are discussed. In agreement with other reports, the importance of the earliest possible surgery, without which prognosis is almost always poor, is reiterated.