The Production of Platelet-Activating Factor during Hemodialysis

Regenerated cellulosic membranes (CU) induced the aggregation of plasma-free human neutrophils when recirculated in a dynamic model of dialysis without the patient on the circuit. Neutrophil aggregation was linked to the production of PAF by these cells. In the absence of detectable PAF production, no neutrophil aggregation occurred, as observed during recirculation with polymethylmethacrylate (PMMA) membranes. With polycarbonate (PC), PAF production and aggregation of neutrophils were both almost half the values with CU. PAF production was studied in ten hemodialysis (HD) patients tested twice with CU and once with PC and PMMA membranes. PAF was extracted in the venous blood during filling of the dialyser for 9/20 of patients with CU (3.1 ± 2.9 ng/ml, mean ± 1 S.D.) a membrane that induced marked leukopenia (> 50% of basal values at 15 min), C3a des Arg generation (> 500% at 5 min), and plasma levels of the elastase-alpha1-proteinase inhibitor complex (> 500% at the end of HD). Membranes such as PC and PMMA showing intermediate or low potential to induce leukopenia and C3a des Arg generation, respectively, did not trigger the production and release of PAF in detectable amounts at any interval. However, with PMMA, plasma neutrophil elastase was significantly higher than baseline at the end of dialysis. These levels were not significantly different (p < 0.05) from those observed with CU and PC membranes

In vitro Complement-Independent Activation of Human Neutrophils by Hemodialysis Membranes: Role of the Net Electric Charge

Polymethylmethacrylate (PMMA) membranes with different net electric charges and percentage water contents (anionic 71%, neutral 70%, cationic 75%) were evaluated for their ability to stimulate plasma-free human polymorphonuclear neutrophils (PMN), and compared for potency to cuprophan (Cu), already described as being a potent trigger of PMN. The release of lysozyme, β-glucuronidase, lactic dehydrogenase (LDH), and the generation of a platelet aggregating activity were studied in the supernatants from plasma-free human PMN incubated with different membranes. The PMN intracellular content of neutrophil cationic proteins (NCP), elastase, and cathepsin G were also studied by immunofluorescence using specific antisera on smears of PMN before and after incubation with each membrane.

Only cationic, but not anionic or neutral PMMA induced a marked release of lysozyme (range 20-25% of the sonicated control, assumed as 100%), and β-glu-coronidase (40-43%), and marked depletion of the intracellular content of NCP, elastase, and cathepsin G, suggesting a degranulation process. Platelet aggregating activity was generated and referred to the release of platelet activating factor (PAF) only in the supernatants from PMN incubated with cationic, but not with anionic, or neutral PMMA membranes.

These results indicate that modification of the net electric charge can per se turn PMMA, commonly recognized as inert, into a material with marked PMN activating effects, comparable to those of Cu, a highly reactive polymer.

Hypervitaminosis B12 in Maintenance Hemodialysis Patients Receiving Massive Supplementation of Vitamin B12

We have administered routinely a multivitamin preparation containing a megadose of B12 to 106 hemodialysis patients after dialysis treatments. We found that these patients had very high levels of serum vitamin B12 which returned to original values only after a period of three years after stopping the vitamin. Discontinuing therapy had no effect on hemoglobin, mean erythrocyte corpuscular volume, or motor nerve conduction velocity. It is not known whether maintaining a prolonged high level of vitamin B12 is harmful. However, animal and epidemiologic studies have suggested that both cobalamin and cobalt may be potentially toxic. In view of the absence of demonstrable benefit and the possible risk of toxicity, we believe that the use of such megadose vitamin compounds in dialysis patients should be re-evaluated.

Daily Dialysis Kt/V and Flexible Schedules: Is it Possible to Control Efficiency, When and How?

Background

Daily hemodialysis is a promising treatment schedule but uniform criteria for defining efficiency are lacking.

Methods

On our daily dialysis (DD) schedule, duration is flexible (2–3 hours, patients are free to add up to 30min/session), Qb 250–350 mL/min; dialyser 1.6–1.8 m2. Study was performed on 12 pts on DD for ≥2 months, with ≥4 Kt/V on subsequent days, tested in the same laboratory. Goal: To evaluate variability and identify a simple method for weekly calculation, Kt/V was assessed for 133 sessions.

Results

On flexible DD, variability of Kt/V-session is high (relative error 4.9%-22%). On flexible schedules, within the time range chosen (2–3 hours) variability of average hourly Kt/V is lower (standard deviation: min (0.014; max (0.052 hour, relative error 4.9%-10%) allowing calculation of weekly Kt/V (averaging 3 sessions: relative error <6%) suitable for clinical practice.

Conclusions

Flexible schedules, allowing patients to increase treatment time, are an interesting clinical option, but a challenge for Kt/V assessment.

Prescription and Surveillance of the Acetate-Free Biofiltration Sessions: The Bicarbonate Cycle

A computerized system, structured by 4 different models concerning urea depuration, and bicarbonate and sodium handling in acetate-free hemodiafiltration has been conceived for integrated use covering each step of the therapeutic cycle, from a) the prescription of the session to b) its delivery, up to c) the dose - response analysis: the system, now fully developed for the bicarbonate cycle, covers both working areas; the medical one, with a program implemented on a Personal Computer, called Skipper which deals with steps a) and c), and the nursing area, with a program built into the dialytic equipment software. The Skipper program supports the prescription step (a) testing the session schedule by bicarbonate, sodium and urea kinetics. The dialytic equipment, (step(b)) using a different program, on the basis of the scheduled parameters memorizes the end-session plasma bicarbonate level and reacts to any modifications of the parameters regarding blood flow and fluid reinfusion flow suggesting opposite changes in order to reach the scheduled results. Finally (step (c)), the Skipper system statistically evaluates the observed end session bicarbonate plasma level with an expected value with upper and lower confidence bounds obtained by a multiple regression analysis performed on a large population of patients.

The Catheter as Ariadne's Thread to Follow the Path of Peritoneal Dialysis (PD) through the Long-Term Experience of a Center

In our institution, the first patient was treated by HD in 1955. In the middle of the '60s, the PD technique, revised by Maxwell (1), was implemented. The access to peritoneum was obtained by repeated puncturing of the abdomen, the catheter being removed after each session. In 1966, our first results on one year of PD were published (20 patients treated, 13 affected by ARF and 7 by CRF, for a total number of 150 sessions). Since 1967, the procedure of the repeated punturing was improved by the Seldinger technique. The efficiency of the PD intermittent treatment was increased with the “fast shift” schedule and PD automation was pursued with the project of a cycler (1968). The first CRF patients were treated by fast shift PD.

In the late intermittent PD phase, the adoption of permanent catheters, destined to endure in our practice, the rigid and the soft indwelling for long-term treatments, allowed us to launch programs of home and nocturnal PD.

With the incoming CAPD age, the greatest care was directed to the role of the catheter. The adoption of the surgical insertion by paramedian approach through rectus muscle, minimized, in our experience, the early complications.

With the reduction of peritonitis rate, the later catheter complications increased in terms of patient discomfort, hospitalization and technique survival. On those grounds, in our institution a prospective trial on a ten year period was undertaken to compare, in terms of late complications rate, new versions of the classic Tenckhoff straight catheter (ST). The surgical insertion method was adopted for all the types, for a total of 196 catheters in 163 CRF patients. The tip displacement rate (12.2% with ST) decreased, albeit non significantly, with Swan Neck (7.9%), but was markedly and significantly reduced (1.0%) with the Self-Locating (SL) catheter experience. The surgical insertion of SL was comparable to that of ST. For those reasons, in recent years, in our institution the SL catheter became the first choice catheters for CRF patients.

[The concept of ultrapure solution online production]

Online preparation of dialysis fluid, i.e., continuous mixing and immediate use, was introduced in 1964 and has contributed significantly to the expansion of dialysis therapy through simplified handling, improved microbiology, and enhanced efficiency. Online prepared replacement solution for hemofiltration was shown to be clinically safe as early as 1978, but the implementation was delayed for 20 years because of regulatory conservatism. Online preparation of sterile and pyrogen-free solutions for infusion is based on the use of water and concentrates that are mixed and distributed in a hygienically designed and maintained flow path. Ultrafilters with known retention capacity are placed in strategic positions to remove bacteria and endotoxins, which gives a sterility assurance level of at least six magnitudes, as required by the pharmacopoeia for sterile products. Microbiologic testing of the fluid should be applied when designing, validating, and troubleshooting online systems but not for routine quality control, because it only gives retrospective information. Quality assurance has to be built into a system and the way it is operated. The use of ultrapure dialysate must be considered as a suitable option for all hemodialysis modalities. To achieve this goal, one must keep in mind that ultrapure dialysate and infusate result from a complex chain of production where ultra-purity and/or sterility of the final solution relies on the weakest or worst component of the chain. Online fluid preparation, when properly performed, is safe, simple, and cost-effective and enhances the efficiency as well as the biocompatibility of dialysis therapy.

EPO or Not-EPO? An Evidence Based Informed Consent

Background

Informed consent is crucial in therapeutic choices; however, the forms presented to patients are often locally developed and information may not be homogeneous.

Objective

To prepare an evidence-based model for informed consent, applied in the case of erythropoietin therapy (EPO) as a teaching tool for medical students.

Methods

Methodological tools of Evidence-Based Medicine (EBM) were developed within the EBM Course in the Medical School of Torino, Italy, as problem solving and patient information tools (5th year students work in small groups under the supervision of statisticians, epidemiologists and experts of internal medicine - nephrology in this case).

Results

Methodological and ethical problems were identified: in the pre-dialysis field, evidence from randomized clinical trials (RCT) is scant; how to use evidence gathered in dialysis? How to deal with implementation? How with the mass media? Do we need to discuss the drug choice with the patients? How to deal with rare and severe side effects?). The “evidence” was searched for on Medline/Embase, by using key-words and free terms. About 680 papers were retrieved and screened. Forms available on the Internet were retrieved and a general scheme was drawn: it included 5 areas: title, aim and targets (patients and family physicians); search strategies and updating; pros and cons of therapy; alternative options; open questions.

Conclusions

EBM may offer valuable tools for systematically approaching patient information; the inclusion of this kind of exercise in the Medical School EBM courses may help enhance the awareness of future physicians of the correct communication with patients.

Twenty years of renal replacement therapy in a type 1 diabetic patient: advantages of a multiple choice dialysis system

The prognosis of diabetic patients on renal replacement therapy (RRT) is usually poor. We report on the type 1 diabetic woman with the longest RRT follow-up in our area: over 20 years, half on dialysis, half with a renal graft. CS started RRT at age 27 on peritoneal dialysis (3 years), continued until an underdialysis syndrome developed, was switched to acetate dialysis and, because of poor tolerance, to hemofiltration which with good clinical results, allowing her to become the first Italian patient on home hemofiltration, which continued for 5 years. A cadaver graft lasted for the subsequent decade, despite several complications; afterwards she resumed bicarbonate dialysis, choosing a frequent home hemodialysis schedule. Despite several vascular access problems, her clinical conditions were good enough to candidate her for a second renal transplant, performed 3 years ago. This history of active self-care may draw attention to the advantages of a multiple choice dialysis network.

[Costs of dialysis in hospitalised patients with acute or chronic renal failure, according to area of treatment]

BACKGROUND

In Italy, dialysis reimbursement is regulated by the "Tariffario delle prestazioni ambulatoriali" (G.U. N 216, 14/9/1996), which does not take into account separately the dialysis sessions performed in hospitalised patients. In these cases the dialysis activity is considered within the final DRG (Diagnosis Related Group). Aim of the study was an analysis of production costs of dialysis performed in hospitalised patients, according to the setting in which dialysis is performed (Intensive Care Units (ICUs), other Units, hospital dialysis ward).

METHODS

The direct production costs were assessed by the "bottom-up" technique logic (cost definition from the single elements needed for producing the treatment) referring to specific Cost Centres. The main items considered were health-care staff, dialysis supplies and hardware, blood tests, dialysis data recording and transmission.

RESULTS

During the year 2000, there were 4,450 treatments performed in 490 patients. They included 924 haemodialyses in ICUs; 2,531 in the nephrology hospital dialysis ward; 602 peritoneal dialysis treatments in ICUs-other wards, 393 in the nephrology ward. Direct cost per haemodialysis treatment ranged from 276.05 E (UF) to 413.46 E (HF) in ICU, from 170.47 E (Bicarbonate Haemodialysis) to 275.36 E (Slow Haemofiltration) in hospital dialysis ward; for peritoneal dialysis between 128.95 E (CAPD in dialysis ward) and 282.10 E (CAPD in ICU/other Units). During the year 2000, the global cost of production was 1,038,346.65 E.

CONCLUSIONS

The cost of dialysis in hospitalised patients is high. A dedicated budget is needed to avoid deficits, particularly in highly specialised Units of large referral hospitals.

[Daily dialysis: evaluation of the first year of experience at home and in a limited care center]

BACKGROUND

Among self dialysis treatments, daily dialysis is encountering a growing interest. Aim of this study was to evaluate results of the first year of daily dialysis in our Center.

METHODS

Since November 1998, twelve patients started daily dialysis. One patient started RRT on daily dialysis; one patient was in training; 8 were on home dialysis, 3 in the limited care center. Selection of patients was performed according to wide acceptance criteria as for age (range 33-61 years), dialysis follow-up (range 1-23 years), comorbidity (=/>1 comorbid factor present in 8). Dialysis schedule consisted of 6 sessions per week (2-3 hours), blood flow 250-320 ml/min, individualized dialysate. Occasional shift to 3-4 times per week were allowed for logistic or working reasons.

RESULTS

Results were analyzed taking into account patient satisfaction and main clinical parameters. In 9/12 the choice of treatment resulted from both clinical reasons and patient preferences, while in 3 was due to clinical indications (1/3 dropped out). The main reasons of choice were logistic or research of the best treatment. The most common fears regarded fistula and needle puncturing. Despite the time unconvenience, the rapidly regained well being was the reason for choosing this treatment. Also in this relatively short follow-up the favorable results reported as for weight gain, blood pressure control and metabolic pattern are confirmed. The few side effects were multifactorial (fistula thrombosis after blood pressure normalization, 2 recurrences of atrial fibrillation).

CONCLUSIONS

In conclusion, daily dialysis resulted also in our centre as a promising alternative even in difficult patients.

Patient knowledge and interest on dialysis efficiency: a survey

BACKGROUND

Therapeutic compliance is fundamental on dialysis; however following a therapy requires a prior understanding of it. Aim of the study was to assess the need and interest for information on dialysis efficiency and to prepare a dedicated teaching tool.

METHODS

72 patients, on hemodialysis in two limited-care satellite units, were given a questionnaire testing knowledge and interest on dialysis efficiency. In a subsequent second phase, following patients' suggestions, a cartoon book was prepared and opinions recorded.

RESULTS

63 patients' returned the questionnaire. 79.4% had basic knowledge on routine blood tests, 30.1% were aware of their specific meaning. All patients asked for further information, preferring books to other media. The book "Kt/V as cartoon" was distributed; 71.2% read it, 93% scored it as good-very good. In the Unit employing flexible dialysis schedules, 22/42 patients increased dialysis time.

CONCLUSIONS

Despite insufficient knowledge on dialysis efficiency, patient interest is high. An educational program is feasible and may also give practical results, such as self-increase in dialysis time.

Limits of aortic stop flow infusion chemotherapy in the treatment of advanced cancer

BACKGROUND

Advanced and relapsed tumors remain a challenging disease with a poor and dismal prognosis. Our choice for inoperable tumors consists in a percutaneous treatment strategy involving intra-arterial chemotherapy and hemofiltration, with previous blood stop-flow, which allows high doses of Cisplatin-cisplatinum, cis-diammine-dichloroplatinum (CDDP) and Mitomycin C (MMC) in the tumor-bearing area with minimal systemic toxicity.

METHODS

We analyse the morbidity and mortality associated with stop-flow in 20 patients with unresectable and/or metastatic thoraco- abdominal tumors, non responders to prior systemic chemotherapy.

RESULTS

In our experience, the rate of major side effects of the procedure was 31% with a mortality of 5%. The side effects were related to the radiological procedure and to the chemotherapic treatment. A 74-year-old patient died for acute kidney toxicity within 15 days after the procedure. The other transient toxicity symptoms recorded were: nausea, vomiting, increasing of creatinine levels, diplopia and appearance of necrotic ulcer associated to chemotherapic drugs. Concerning the complications related to the radiological technique, the main problem was the rupture of the balloon stop-flow catheter in four patients.

CONCLUSIONS

Stop-flow is a new procedure that could develop in the future, thanks to the possibility of obtaining a higher dose intensity of chemotherapic drugs in districts or organs affected by advanced tumors, with less systemic side effects. Unfortunately, the uncertain results in terms of increasing survival and the default of effective devices are to be resolved for a wider application of the procedure.

Daily dialysis Kt/V and flexible schedules: is it possible to control efficiency, when and how?

BACKGROUND

Daily hemodialysis is a promising treatment schedule but uniform criteria for defining efficiency are lacking.

METHODS

On our daily dialysis (DD) schedule, duration is flexible (2-3 hours, patients are free to add up to 30 min/session), Qb 250-350 mL/min; dialyser 1.6-1.8 m2. Study was performed on 12 pts on DD for > or = 2 months, with > or = 4 Kt/V on subsequent days, tested in the same laboratory.

GOAL

To evaluate variability and identify a simple method for weekly calculation, Kt/V was assessed for 133 sessions.

RESULTS

On flexible DD, variability of Kt/V-session is high (relative error 4.9%-22%). On flexible schedules, within the time range chosen (2-3 hours) variability of average hourly Kt/V is lower (standard deviation: min (0.014; max (0.052 hour, relative error 4.9%-10%) allowing calculation of weekly Kt/V (averaging 3 sessions: relative error < 6%) suitable for clinical practice.

CONCLUSIONS

Flexible schedules, allowing patients to increase treatment time, are an interesting clinical option, but a challenge for Kt/V assessment.

Modelling the "ideal" self care--limited care dialysis center

Limited care dialysis is an interesting option, which has gained attention in several settings because of the aging of the uremic cohort. The aim of this study was to assess its potential in the Piedmont region in northern Italy, evaluating patients' and care-givers' preferences and testing them in a mathematical model of organisation. The study was conducted in the satellite unit of a university hospital (200-210 dialysis patients), following 35 patients (15 at home, 20 in the center, 10 on daily dialysis). Opinions were collected with a questionnaire and features identified were empirically tested through a simulation model. Most patients (34/35) preferred a small unit, with a stable caring team. Further options were flexibility of dialysis schedule, multiple treatment options, integrated center/home care. These needs could be met by a flexible organization including conventional dialysis (3/week) and daily dialysis (6/week). We employed a simulation model (ARENA software) to calculate the nurses required for each shift and the opening hours and best schedule for the unit. Addition of daily dialysis (2-3 hours) to two conventional 4-5 hour sessions to increased the number of patients followed or "spared" beds, ensuring flexibility. According to patients' best choice (7 dialysis stations), and to the recorded calls, the needs are for two nurses per shift, two shifts per day and six nurses for up to 30 patients in limited care. In conclusion, small centers with flexible schedules can tailor dialysis to patients' needs. A managerial approach is valuable for testing cost/benefit ratios in specific contexts.

[Relationship between risk profiles, prognosis, and outcome of patients with acute renal failure treated with dialysis]

BACKGROUND

The paradox of the increased mortality in the patients with acute renal failure (ARF) although submitted to better cares and newer renal replacement therapies (RRT) has recently prompted to the use of quantitative individual severity scores (ISS) calculating for each patient an individual death probability (DP) in correlation with the risk covariates found before the start of RRT; beside the clinical use, the ISS allow an evaluation of the effect of strategies and modalities of treatments as quantitative additive factors eventually added or subtracted to the base-line individual background of risk. The ideal index should be chosen on the basis of its precocity (origin just at the start of therapy), sensitivity (true positive against false positive results), universality (independence from the development set) and discriminative power (the capability to discern patients potentially treatable from those with an unchangeable prognosis). Indexes already validated in their development set should be used and studied into a different set ("evaluation set").

METHODS

The aim of this study has been: to evaluate a literature index (ATN-ISS, Liaño, developed prospectively in a remote set) in the local (A) environment on 340 patients with ARF successively treated with dialysis (mostly hemo-filtration) studied retrospectively along a 4 year period in our regional hospital and compare its performances with a local index (PDTOR) developed by logistic analysis in the same pool; the fitness of both tests to the real outcome has been evaluated by the Limeshow test and by ROC curves; to compare both indexes in a remote environment (B) of a dialytic pool of 345 patients extracted by a group of 25721 patients treated by 25 Italian ICU (Archidia Study group). The responses of the two indexes have been compared even with the index (SAPSII) prospectively generated at the admittance in the ICU by the Archidia Group.

RESULTS

In the local set (A) TOR-ISS fits well with the outcomes (Limeshow test C2 = N.S.) as expected being evaluated in its own "development" set, while ATN-ISS significantly underestimates deaths, perhaps working on a retrospectively built data-base, that could contain fewer risk elements than necessary. (B) In the remote set, ATN-ISS fits very well, while TOR-ISS significantly overestimates expected deaths, for its retrospective origin or for a real lower death incidence compared to that of its development set. SAPSII shows no correlation at all with the outcome because its calculation is often well before (10 days on average) than the actual start of dialytic treatment.

CONCLUSIONS

In conclusion ATN-ISS, an index built prospectively on a large cohort of patients, fits correctly in a remote prospectively built evaluation set. Retrospective built indexes or data-base don't allow a correct ISS evaluation while ICU indexes (SAPSII, APACHE), generated at the admittance in the ICU should not be used for ARF patients submitted to dialysis.

[Research potential of a regional registry]

BACKGROUND

The need for data bank gathering information in dialysis patients is as old as dialysis. Dialysis Registries presently active are characterized by different policies of data gathering (large vs small number of information) and of use (research vs economical or clinical purposes). Aim of the work was a discussion on the use of a Regional Registry (RPDT, Regional Registry of Dialysis and Transplantation of Piedmont, Italy), gathering since 1981 a wide set of information (about 80 items) on all patients treated in a relatively small area (about 4,300,000 inhabitants).

METHODS

Two researches were selected: the first includes patients treated for > or = 20 years by RRT. Cases were identified on the basis of RPDT data and an inquiry regarding all patients was performed, with specific interest on comorbidity. The second includes diabetic patients on regular RRT, a sample of which was further analyzed in high detail.

RESULTS AND CONCLUSIONS

While a Regional Registry, even gathering a wide set of data is unable to answer to the most qualitative questions, such as quality of life, its archives are a powerful tool to identify cases. Furthermore, ad hoc inquiries may represent a way to control quality of data or to test new fields to be studied. In the case of patients with long RRT follow-up, comorbidity questions were tested before being included on RPDT. In the case of a sample of diabetic patients, type of diabetes and cause of ESRD were controlled. This biunivocal relationship between clinical work-up and epidemiological archives may often interest future perspectives.

[Quality of data or quality of care? Comparison of diverse standarization methods by clinical severity, based on the discharge form, in the analysis of hospital mortality]

Using discharge abstract data, we analysed hospital mortality comparing four different methods of risk adjustment. All patients discharged from the S. Giovanni Battista (Molinette) hospital in Turin (Italy) between January 1996 and June 1999 (n = 169,746) were classified with All Patient Refined--Diagnosis Related Groups (APR-DRG). A first analysis evaluated the time trend of hospital mortality by semester. A second analysis compared hospital mortality during the last 12 months among eight units of internal medicine (n = 5592). All comparisons were made through logistic regression models. As the quality of discharge abstracts increased during time and showed variation among units with similar patients, all comparisons were repeated using four models, characterised by increasing predictivity and sensitivity to quality of data. In addition to crude comparisons (A), the other models included as risk factors: B) age and emergency admission; C) same as 'B' plus expected mortality by APR-DRG; D) same as 'B' plus expected mortality by APR-DRG and risk of death subclass. If no risk factors were considered (A), hospital mortality showed an increasing trend, with an odds ratio (OR) of 1.02 by semester, with a 95% confidence interval (CI) between 1.01 and 1.03. The association was weakened when age and mode of admission were taken into account (B) and disappeared when the APR-DRG expected mortality was also considered (C) (OR = 1.00; CI = 0.98-1.01). Finally, if the comparisons were adjusted also for the expected mortality by APR-DRG and risk of death subclass (D) a reversed trend appeared (OR = 0.95; CI = 0.94-0.97). The comparison among the units of internal medicine gave discordant results according to the method used to adjust for confounders. The most striking variations were detected for those units with the best and the worst clinical data. The unit with the poorer clinical data (average number of diagnoses per patient = 2.9) showed a crude OR of 1.38 (CI = 0.99-1.93) and an adjusted OR (D) of 1.71 (CI = 1.10-2.66); the unit with the best quality of data (average number of diagnoses per patient = 4.4) changed the OR from 1.55 (CI = 1.06-2.26) (A) to 0.66 (CI = 0.37-1.17) (D). In conclusion, these results confirm the high sensitivity of the APR-DRG classification to the quality of data and, more in general, suggest to be prudent when using powerful instruments like this to assess quality of care, especially if the quality of data among the units compared is less than optimal or not homogeneous.

[Complex vascular access]

Availability of a proper vascular access is a basic condition for a proper extracorporeal replacement in end-stage chronic renal failure. However, biological factors, management and other problems, may variously condition their middle-long term survival. Therefore, personal experience of over 25 years has been critically reviewed in order to obtain useful information. In particular "hard" situations necessitating complex procedures have been examined but, if possible, preserving the peripherical vascular features.

Elderly patients on dialysis: epidemiology of an epidemic

The increase in the incidence of elderly patients starting dialysis has been as sharp, during the 1980s-1990s, as an epidemic (+70%, +150% in different settings). According to this study, performed in Piemonte, northern Italy, the process is still ongoing. During the period 1981-93, according to the Regional Registry of Dialysis and Transplantation (RPDT: data on 100% of centres and patients), the cohort on treatment increased by 79.5% and the annual incidence by 48.3%; the increase is limited to older people and is greater in males. Nephroangiosclerosis/ischaemic renal disease and diabetes mellitus are the main diagnoses. Since the increase of elderly patients is still ongoing, forecasts are difficult; according to a computer simulation, a plateau of patients on treatment is reached only if incidence is stabilized, While it is impossible to exclude a decrease in hidden selection or an increase in referral, complex modifications at the overall population level are presumably at the basis or the increase of elderly patients on dialysis. Despite the increase in average age, however, survival improved throughout the period; this confirms the interest towards the open dialysis system adopted in Piemonte, which is characterized by easy shifts among treatments and by the widespread use of high tolerance techniques.

Prescription and surveillance of the acetate-free biofiltration sessions: the bicarbonate cycle

A computerized system, structured by 4 different models concerning urea depuration, and bicarbonate and sodium handling in acetate-free hemodiafiltration has been conceived for integrated use covering each step of the therapeutic cycle, from a) the prescription of the session to b) its delivery, up to c) the dose-response analysis: the system, now fully developed for the bicarbonate cycle, covers both working areas; the medical one, with a program implemented on a Personal Computer, called Skipper which deals with steps a) and c), and the nursing area, with a program built into the dialytic equipment software. The Skipper program supports the prescription step (a) testing the session schedule by bicarbonate, sodium and urea kinetics. The dialytic equipment, (step(b)) using a different program, on the basis of the scheduled parameters memorizes the end-session plasma bicarbonate level and reacts to any modifications of the parameters regarding blood flow and fluid reinfusion flow suggesting opposite changes in order to reach the scheduled results. Finally (step (c)), the Skipper system statistically evaluates the observed end session bicarbonate plasma level with an expected value with upper and lower confidence bounds obtained by a multiple regression analysis performed on a large population of patients.

High level expression and purification of the enzymatically active cytoplasmic region of human CD45 phosphatase from yeast

The cytoplasmic region of human CD45 corresponding to residues 584-1281 was inserted downstream of the alcohol dehydrogenase promoter and transfected into a haploid strain of yeast. Expression of recombinant CD45 in yeast reached as high as 5% of the soluble protein. Following removal of cellular debris by centrifugation and an ammonium sulfate precipitation step, the enzyme was purified using phenyl-Sepharose chromatography, preparative gel filtration, Mono Q anion exchange chromatography and a final analytical gel filtration step. Enzymatically active material with a purity of > or = 98% was obtained with a yield approaching 50%. The final product gave a Km of 5.5 mM and a Vmax of 87.5 U/mg with p-nitrophenylphosphate and a Km and Vmax of 0.167 mM and 185 U/mg, respectively, with a phosphotyrosine peptide. The native enzyme purified from Jurkat cells showed comparable Kms with both substrates to the recombinant enzyme but displayed substantially lower Vmax values for both substrates.

Beta-2-microglobulin serum profiles in different settings of mass transport and fluid pyrogen content

Different beta 2-microglobulin (beta 2m) serum profiles have been related to dialytic membranes, mass transport and/or patient immune stimulation. Eight patients were followed by cycles of four sessions: hemodialysis (HD), hemodiafiltration (HDF), acetate-free HDF (AFH), hemofiltration (HF) by filters on synthetic membranes (polysulphone = 4; methylmethacrylate = 4); pre- (A) and post- (B) measurements in the fourth session, and at the start of the next one (C), beta 2m lipopolysaccharide content of the fluids (LPS), and monocytes in vitro and spontaneous production of interleukins (IL); IL-1-IL-6 and tumor necrosis factor (TNF) were measured. In HD, beta 2m (mg/liter), corrected for ECV distribution, did not change (A = 36.5 +/- 10, B = 37 +/- 9, C = 36.4 +/- 9.7). In HDF, lower basal beta 2m (P < 0.001; A = 26.5 +/- 9) still decreased (B = 9.13 +/- 6.2), boosting subsequently to C = 21.6 +/- 14, as in AFH (A = 24.5 +/- 7, B = 11.2 +/- 2, C = 25.3 +/- 9) and in HF (A = 26.6 +/- 7; B = 8.5 +/- 4; C = 25.6 +/- 11). LPS (EU/ml) decreased (P < 0.001) from HD fluids (0.41 +/- 0.1) to HDF (0.28 +/- 0.1), AFH (0.15 +/- 0.1) and HF (0.04 +/- 0.05) but IL-1 and IL-6 were found in greater concentrations in HDF and AFH versus HD and HF, probably due to back-filtration. Beta 2m in different modes of dialytic treatments seem better correlated with the amount of convective transport rather than with the selected markers of immune stimulation.

Atrial natriuretic factor and concomitant hormonal, hemodynamic and renal function changes after slow continuous ultrafiltration

We treated a patient with refractory biventricular heart failure, dilutional hyponatremia and prerenal azotemia, by means of ultrafiltration. After ultrafiltration, gas exchange and cardiac output improved, with concomitant reduction of systemic and pulmonary vascular resistances. Despite a decrease of right atrial and wedge pressure, atrial natriuretic factor rose and plasma renin activity decreased.

[Long-term results of high-tolerance extracorporeal methods in the light of the new high-efficiency treatments]

While the efficiency of treatment has been recently related to long-term clinical outcome, the relevance of tolerance on this subject, even on critically ill patients, has seldom been evaluated, for the limited size of single pools on high tolerance dialytic treatments (HTT) and the flux of pts. among treatments. Since 1981, on 2243 pts on files of the Dialytic Piedmont Regional Registry, 1399 treatments on acetate-hemodialysis (HD), 1153 on bicarbonate dialysis (BC) and 249 hemofiltration (HF) were compared by survival analysis (Mantel test) and yearly hospitalization rate (YH), according to age, factors of clinical high risk (HR) and presence of diabetes. BC and HF showed on HR pts. LTS comparable to HD (at 1 yr. 82, 78.3 vs 76.77%) despite the higher age, and the lower proportion of first choice (38.9%, 25% vs. 83.5%) testifying successful treatment of more critical cases. On non HR pts. HF, a less efficient treatment vs BD and AD, showed slightly reduced LTS (95.2% at 1 yr. vs. 98.1 and 97.9%). HY results higher on HF vs. BD on non HR pts. (10.4 vs. 5.3 and 2.1%) but improves on HR pts. (10.7 vs. 12.5%) and is lower than BC on diabetics (8.3 vs. 14.5%) (p less than 0.01).

The production of platelet-activating factor during hemodialysis

Regenerated cellulosic membranes (CU) induced the aggregation of plasma-free human neutrophils when recirculated in a dynamic model of dialysis without the patient on the circuit. Neutrophil aggregation was linked to the production of PAF by these cells. In the absence of detectable PAF production, no neutrophil aggregation occurred, as observed during recirculation with polymethylmethacrylate (PMMA) membranes. With polycarbonate (PC), PAF production and aggregation of neutrophils were both almost half the values with CU. PAF production was studied in ten hemodialysis (HD) patients tested twice with CU and once with PC and PMMA membranes. PAF was extracted in the venous blood during filling of the dialyser for 9/20 of patients with CU (3.1 +/- 2.9 ng/ml, mean +/- 1 S.D.) a membrane that induced marked leukopenia (greater than 50% of basal values at 15 min), C3a des Arg generation (greater than 500% at 5 min), and plasma levels of the elastase-alpha 1-proteinase inhibitor complex (greater than 500% at the end of HD). Membranes such as PC and PMMA showing intermediate or low potential to induce leukopenia and C3a des Arg generation, respectively, did not trigger the production and release of PAF in detectable amounts at any interval. However, with PMMA, plasma neutrophil elastase was significantly higher than baseline at the end of dialysis. These levels were not significantly different (p less than 0.05) from those observed with CU and PC membranes.

Prevention and treatment of aluminum overload in uremic patients: long-term results

The authors evaluate the efficacy of a protocol of prevention and treatment of aluminum (Al) overload in RDT patients during a 7-year period (from 1981, 164 patients, to 1987, 161 patients). Al in dialysate solutions was always less than 25 micrograms/l. Baseline Al levels greater than 100 micrograms/l were found in 22% of patients in 1981 but in none in 1987, while the percentage of values less than 60 micrograms/l increased from 55 to 91%. DFO tests were positive in 54% and 7% of cases in 1981 and 1987, respectively. A clinical diagnosis of Al intoxication was performed in 6 patients in 1981, and no further cases were diagnosed later. DFO treatment (50 mg/kg once a week) was employed preventively in 31 patients owing to positive DFO-tests, and in the 6 Al-intoxicated patients therapeutically. In the former patients none developed clinical intoxication. In the latter group clinical improvement was only temporary in the three parathyroidectomized patients. Al hydroxide [Al(OH)3] as a phosphate binder was tapered off in 1981 and substituted by Al-free chelants. In 1987, 66% of patients were given CaCO3 or Mg (OH)2 alone or in association, while 34% still needed Al(OH)3, although at low dosages (less than 2 g/day). The conclusion is that such a protocol is able to prevent and to treat cases of Al intoxication, albeit only partially.

Clinical and histological results of long-term management of aluminium overloading in uraemic patients with desferrioxamine

Aluminium introxication in uraemic patients has been reported both in epidemic and sporadic forms. Desferrioxamine (DFO) results in strong Al mobilisation, but definitive treatment schedules, times of stop, and actual long-term Al removal her not been established. This study was carried out on three sporadic cases of Al intoxication treated with DFO for 3 1/2, 4 1/2 and 1 years. Clinical and laboratory parameters were employed to check the brain, bone and red cell status. Direct evaluation of Al kinetics showed that actual Al removal may be overestimated. In our experience it did not exceed 100 mg/year, and the ratio (DFO used/Al removed) decreased to 150 g/25 mg after two years of DFO, though considerable tissue deposits persisted in the patient who died after 3 1/2 years of treatment. Despite unexplained EEG worsening, neurological symptoms improved. Relapses, however, occurred after many years of DFO. Bone status improvement, at least in parathyroidectomised patients, proved to be only partial and time-related. The therapeutic effectiveness of DFO in these patients seemed to be exhausted after two years even if Al deposits had not vanished.

Ultrafiltration in the treatment of refractory congestive heart failure

Artificial subtraction of fluids and solutes was evaluated in the course of acute and chronic heart failure when it became refractory to standard intensive medical treatment. A group of 19 patients (mean age 57 years), 9 with ischemic, 2 amyloidotic, 4 valvular, and 4 idiopathic cardiomyopathy, were treated. In 17 patients extracorporeal ultrafiltration (UF) by means of a polysulfonate ultrafilter was adopted along 125 sessions (105 assisted by a roller pump and 20 as a slow continuous ultrafiltrate). In two patients continuous peritoneal dialysis was adopted. In every case UF was well tolerated. Ultrafiltrate volumes ranged from 1680 to 3500 ml for every session with corresponding Na losses ranging from 194 to 434 mEq/session. Improved clinical and functional status with reduction of edema was observed in 17 of 19 patients. In 12 patients UF could be discontinued due to restored response to diuretics; 5 of these patients could subsequently undergo heart surgery (1 transplant, 3 valve replacement, 1 coronary bypass). The remaining 7 patients survived on medical therapy alone for an average of 228 days. In 7 of 19 cases, UF could not be discontinued, and these patients died after an average of 23 days of treatment. In conclusion, UF proved to be effective in eliminating salt-fluid overload and restoring response to medical treatment. Patients who are potential surgical candidates seem to be the most suitable for UF.

In vitro complement-independent activation of human neutrophils by hemodialysis membranes: role of the net electric charge

Polymethylmethacrylate (PMMA) membranes with different net electric charges and percentage water contents (anionic 71%, neutral 70%, cationic 75%) were evaluated for their ability to stimulate plasma-free human polymorphonuclear neutrophils (PMN), and compared for potency to cuprophan (Cu), already described as being a potent trigger of PMN. The release of lysozyme, beta-glucuronidase, lactic dehydrogenase (LDH), and the generation of a platelet aggregating activity were studied in the supernatants from plasma-free human PMN incubated with different membranes. The PMN intracellular content of neutrophil cationic proteins (NCP), elastase, and cathepsin G were also studied by immunofluorescence using specific antisera on smears of PMN before and after incubation with each membrane. Only cationic, but not anionic or neutral PMMA induced a marked release of lysozyme (range 20-25% of the sonicated control, assumed as 100%), and beta-glucuronidase (40-43%), and marked depletion of the intracellular content of NCP, elastase, and cathepsin G, suggesting a degranulation process. Platelet aggregating activity was generated and referred to the release of platelet activating factor (PAF) only in the supernatants from PMN incubated with cationic, but not with anionic, or neutral PMMA membranes. These results indicate that modification of the net electric charge can per se turn PMMA, commonly recognized as inert, into a material with marked PMN activating effects, comparable to those of Cu, a highly reactive polymer.

Hypervitaminosis B12 in maintenance hemodialysis patients receiving massive supplementation of vitamin B12

We have administered routinely a multivitamin preparation containing a megadose of B12 to 106 hemodialysis patients after dialysis treatments. We found that these patients had very high levels of serum vitamin B12 which returned to original values only after a period of three years after stopping the vitamin. Discontinuing therapy had no effect on hemoglobin, mean erythrocyte corpuscular volume, or motor nerve conduction velocity. It is not known whether maintaining a prolonged high level of vitamin B12 is harmful. However, animal and epidemiologic studies have suggested that both cobalamin and cobalt may be potentially toxic. In view of the absence of demonstrable benefit and the possible risk of toxicity, we believe that the use of such megadose vitamin compounds in dialysis patients should be re-evaluated.

Three-year follow-up after withdrawal of iron therapy in uremic patients on regular dialytic treatment

Iron supplementation is commonly recommended in uremic patients undergoing regular dialytic treatment in order to correct a presumed iron deficiency due to impaired absorption and dialytic losses. Serum ferritin levels show an iron overload in 83% of 136 patients on 1.25 g/year i.v. iron therapy. After the withdrawal of iron therapy, directly correlated ferritin levels and percentage transferrin saturation decreased slowly, except in carriers of HLA-A3 antigens and in polytransfused patients. In these latter patients, desferrioxamine reduced but did not normalize the iron balance. The 16 patients who never received iron therapy showed a normal iron balance over a 3-year follow-up. Despite iron-ferritin therapy, 11 patients with baseline ferritin values at the lower normal limits showed a tendency toward further depletion. Orally administered bivalent iron seems to be more promising in normalizing iron-deficient patients without potentially harmful overloading.

Heparin transfer across the rabbit peritoneal membrane

Variable quantities of heparin have been proposed to avoid intraperitoneal clotting during peritoneal dialysis without the risk of systemic effects, because heparin is presumed to be incapable of passing through the peritoneal membrane. This study set out to verify this assumption by using labeled heparin in experimental dialysis in 7 New Zealand white rabbits. Heparin was labeled with 99mTc. Labeling quality, assessed by two chromatographic checks, showed less than 5% of free pertechnetate. Chromatographic determinations showed more than 95 and 80% of labeled heparin in inflow and outflow dialysates and in blood samples respectively. Following sodium thiopental anesthesia, animals underwent three protocols: a single 15 min cycle of time diffusion with heparin 500 U/l (A), 6 successive 15 min cycles with heparin 500 U/l (B), and a single 3 h cycle with heparin 2,500 U/l (C). Labeled heparin was found in blood organs and urine in variable percentages. The total amount of recovered radioactivity ranged from 1.5% (A) to 20% (C) of that introduced. It may be concluded that heparin passes through the peritoneum according to some law dependent on the amount used and the diffusion time.