[Quantifying dialysis efficiency for middle molecules in haemodialysis and in convective and mixed techniques]. / La quantificazione pratica dell'efficienza dialitica per le medie molecole in dialisi e nelle tecniche convettive e miste.

In contrast to the negative results of the primary analysis, secondary analyses of the HEMO study do support the clinical importance of middle molecule removal. This is in agreement with the findings of large observational studies showing an improvement in mortality and morbidity in dialysis patients treated with high-flux hemodialysis or convective techniques as compared to low-flux hemodialysis. For practical assessment of middle molecule removal, we suggest using the Kt/V of beta2-microglobulin (Kt/Vbeta2-m) with a reference (adequate) value of >or=0.66, which was the average value for the high-flux arm in the HEMO study. For patients on low-flux hemodialysis, where Kt/Vbeta2-m cannot reliably be assessed, we suggest using the Kt/V of vitamin B12 (Kt/VB12), with a reference (adequate) value of >or=0.74, adapted from the findings of the Case Mix Adequacy Study (AJKD 1999). To simplify the routine assessment of these indices, two nomograms are introduced: the first allows to estimate Kt/Vbeta2-m from the post- to pre-dialysis beta2-microglobulin concentration ratio, the second allows to estimate the diffusion dialysis clearance of vitamin B12 from the in vitro dialyzer KoAB12 and actual plasma water flow rate. While waiting for specific trials addressing the issue of dialysis adequacy related to middle molecule removal, clinical experience with the middle molecule indices could provide further quantitative tools for dialysis prescription and favor an increase in dialysis time (or frequency) and/or the use of high-flux hemodialysis and convective techniques.

[Census 2004 of the Italian renal and dialysis units. Basilicata - Calabria - Puglia]. / Censimento 2004 dei Centri di Nefrologia e Dialisi Italiani. Basilicata - Calabria - Puglia.

The Italian Society of Nephrology (SIN) sponsored in 2004 a National Census of the Italian renal and dialysis units. This paper presents the main structural, technical, organizational features, as well as the human resources and the activities of three South-East regions of Italy: Basilicata (B), Calabria (C), and Puglia (P). EPIDEMIOLOGY: incidence of dialysis patients was 149 per million population (pmp) in B, 134 pmp in C and 172 pmp in P; prevalence of dialysis patients 729, 694 and 886 pmp, respectively; prevalence of transplanted patients 188 in B, 264 in C and 249 pmp in P; gross mortality rate of dialysis patients was 12.7% (B), 12.2% (C) and 10.8% (P). TYPE OF VASCULAR ACCESS IN PREVALENT DIALYSIS PATIENTS: arteriovenous fistula: 83.9% (B), 87.7% (C) and 86.5% (P); central venous catheter: 14.2% (B), 8.4% (C) and 11.2% (P); vascular graft 1.9% (B), 3.9% (C) and 2.3% (P). STRUCTURAL RESOURCES: nephrological beds 37, 34 and 88 pmp, respectively; dialysis stations 265, 209 and 207 pmp. PERSONNEL RESOURCES: renal physicians 45 (B), 67 (C) and 64(P) pmp; renal nurses 189, 190 and 207 pmp; each nephrologist cares for 16 (B), 10 (C) and 14 (P) dialysis patients, whereas each renal nurse takes care of 3.8 (B), 3.7 (C) and 4.3 (P) dialysis patients. ACTIVITY: hospitalizations 1378, 1834 and 3439 pmp, respectively; renal biopsies 40 (B), 64 (C) and 107 (P) pmp. The main goal of this project was to create a reference for benchmarking studies. Therefore, data from the Puglia region were compared to data from other regions with similar population size (such as Piemonte and Emilia-Romagna). Moreover, a Census may became a useful qualitative tool for renal registries: this report compares data from the Census with data collected by the dialysis and transplantation registry of the Puglia region. Generally speaking, prevalence for Basilicata and Calabria is close to the Italian one, whereas incidence is inferior; things are opposite in Puglia. Furthermore, compared to Basilicata, Calabria and Italy on average, the Puglia region shows a significant higher number of in-patient beds and a lower DRG weight. Compared to Piemonte, Emilia Romagna and Italy on average, all the three South-East regions do not show differences in number/pmp of dialysis centres. More physicians (nephrologists = 80%) are reported to be active in Puglia and Calabria, compared to Piemonte and Emilia Romagna. Nurses in Puglia look after a greater number of dialysis patients than in Calabria and Basilicata. The number of renal biopsies/ pmp is similar to the Italian mean only in Puglia; it is inferior in the other two regions. These data highlight many differences among these three South-East regions, as well as among Piemonte, Emilia Romagna and Puglia. A relevant inequality in health care structures and resources has been found and discussed.

[Update of the Italian Society of Nephrology Project No. 1 of the 2004-2006 SIN programme]. / Update sul progetto SIN n. 1 del programma SIN 2004-2006: qualità e accreditamento delle strutture di nefrologia, dialisi e trapianto.

In the last few years the Italian Society of Nephrology has addressed many technical-scientific and management aspects to better patient satisfaction. Project No. 1 of the 2004-2006 programme on 'Quality and Accreditation of National Renal Units' focuses on four essential points. The first is the questionnaire mailed to all the Presidents and Regional Delegates on the relationship between Nephrology units, Local Government Health-System and the Regional Healthcare Agency. The results evidence that the 'political' decision-making power of nephrologists decreases in the absence of a national strategy. The second point, in collaboration with the National Census Group, includes the quality analysis and the standardization of resources (human and structural) and management of the Renal Units. The third point is based on 'Educational Courses for Quality and Accreditation' held in Rome (3-5 October 2005: L'Accreditamento all'Eccellenza dell'Unita' Operativa di Nefrologia, Dialisi e Trapianto; 17-19 October 2005: Il Manuale di Accreditamento della Specialità di Nefrologia). The courses aim at training members responsible for each region to hold courses in their specific region to create a network including each single Renal Unit to create an acceptable homogenous language on the models of analysis and on the correct use of 'The Guide for Excellence Accreditation'. The fourth point concerns both the on-line Guide for Excellence Accreditation and 'Peer Review Accreditation' and the NEQUASY (Nephrology Quality System) project. The manual must be 'user friendly' allowing each Centre to self-evaluate using national and regional standards.

Global approach to cardiovascular risk in chronic kidney disease: reality and opportunities for intervention.

The current implementation into nephrology clinical practice of guidelines on treatment of cardiovascular (CV) risk factors in chronic kidney disease (CKD) is unknown. We designed a cross-sectional analysis to evaluate the prevalence and treatment of eight modifiable CV risk factors in 1058 predialysis CKD patients (stage 3: n=486; stage 4: n=430, stage 5: n=142) followed for at least 1 year in 26 Italian renal clinics. The median nephrology follow-up was 37 months (range: 12-391 months). From stages 3 to 5, hypertension was the main complication (89, 87, and 87%), whereas smoking, high calcium-phosphate product and malnutrition were uncommon. The prevalence of proteinuria (25, 38, and 58%), anemia (16, 32, and 51%) and left ventricular hypertrophy (51, 55, and 64%) significantly increased, while hypercholesterolemia was less frequent in stage 5 (49%) than in stages 4 and 3 (59%). The vast majority of patients received multidrug antihypertensive therapy including inhibitors of renin-angiotensin system; conversely, diuretic treatment was consistently inadequate for both frequency and dose despite scarce implementation of low salt diet (19%). Statins were not prescribed in most hypercholesterolemics (78%), and epoietin treatment was largely overlooked in anemics (78%). The adjusted risk for having a higher number of uncontrolled risk factors rose in the presence of diabetes (odds ratio 1.29, 95% confidence interval 1.00-1.66), history of CV disease (odds ratio 1.48, 95% confidence interval 1.15-1.90) and CKD stages 4 and 5 (odds ratio 1.75, 95% confidence interval 1.37-2.22 and odds ratio 2.85, 95% confidence interval 2.01-4.04, respectively). In the tertiary care of CKD, treatment of hypertension is largely inadequate, whereas therapy of anemia and dyslipidemia is frequently omitted. The risk of not achieving therapeutic targets is higher in patients with diabetes, CV disease and more advanced CKD.

[Standardization criteria to ensure the uniformity of data collection by the Italian Registry of Dialysis and Transplantation]. / Criteri di uniformità per la raccolta dei dati del Registro Italiano di Dialisi e Trapianto.

The Italian Registry of Dialysis and Transplantation (RIDT) collects data concerning patients in renal replacement therapy (RRT) sent from Regional Registries. Until 2003, the data were sent in summary tables. From 2004, each region has been sending patient data as single non-summarized forms (i.e. one record for each patient). This paper summarizes the collection criteria and the ideal method to codify data ensuring that data sent to the RIDT are consistent. This standardization process is necessary to ensure the statistical analyzability of the data and their comparability with data from other registries. Moreover, the standardization process is the initial step in allowing the RIDT to obtain clinical data to transform the registry from an epidemiological registry to a clinical governance instrument.

[Regional clinical audit, guideline targets, and local and regional benchmarks]. / L'Audit clinico a livello regionale, Target delle Linee Guida e Benchmarks locali e regionali.

Regional clinical Audit, guideline Targets and local and regional Benchmarks In order to improve the quality of dialysis treatment, we have devised some routines, particularly suitable for electronic data management systems. First, we suggest a systematic monthly analysis of 10 common clinical performance measures (CPM), with the following guideline based targets: predialysis systolic blood pressure (SBP) < 140 mmHg; session length >/= 240 min; dialysis dose (spKt/V) >/=1.3; normalized protein catabolic rate (NPCR) >/=1.2 g/kg/d; hemoglobin (Hb) >/=11 g/dL; serum calcium (Ca) 8.4-9.5 mg/dL; serum phosphorus (P) 3.5-5.5 mg/dL; Ca x P /=20 mmol/L; serum potassium (K) 3.5-6.0 mmol/L. The Hb target should be reached in at least 85% of all maintenance hemodialysis (HD) patients in the unit; for all other targets, an arbitrary >/=80% is proposed. Since the above percentages are quite difficult to reach on a short-term basis, an intermediate local or regional standard (benchmark) could be devised as an average of the percentage of patients who actually reach the targets for each CPM at any dialysis unit in a given regional area; and therefore, from truly comparable patients. As an example, we simulated a regional audit by using the above targets with available data from 398 patients from southern Italy. A further step in this process was to find the cause(s) of failure in each patient who did not reach the targets. To this end, we suggest a systematic search of the well-known factors that could affect each CPM, for each failed patient. As an example, we screened all patients with Hb < 11 g/dL at a single unit, to establish the presence/absence of any common cause associated with inadequate response to epoetin treatment. Moreover, by using criteria for prescribing iron therapy or increasing epoetin dose, we found that some patients did not receive the appropriate therapy after blood sampling results. To avoid this possible common problem, we suggest the need for a monthly report of failure cases for any particular CPM and a check that the appropriate treatment has been delivered to all patients at the dialysis unit. This should also favor guideline implementation.

[Italian Registry of Dialysis and Transplantation: 1996-2001 experience]. / Registro Italiano Dialisi e Trapianto. Esperienza 1996-2001.

The Italian Registry of Dialysis and Transplantation (RIDT) was born in 1996 under the aegis of the Italian Society of Nephrology, and it is organized as a federation of regional registries. This study aimed to completely revise the epidemiological data collected during the first 5 yrs (1996-2001) of RIDT activity to evaluate the trends of the main epidemiological features. During this period, regional registries were not always able to assure complete and exhaustive information according to RIDT requirements, owing to different levels of organization and functioning. To avoid any possible error in data analysis, information inadequately assessed was refused. The incidence of end-stage renal disease (ESRD) patients on renal replacement therapy (RRT) in Italy has increased from 114 pmp in 1996 to 139 pmp in 2001, that means an increase of 3.5%/yr, corresponding to 5718 patients during 1996 and 8000 patients during 2001. Primary renal diseases (according to the EDTA) in incident ESRD patients are vascular and diabetic nephropathy. Main dialysis modality in incident patients was hemodialysis (HD) (85%), while peritoneal dialysis (PD) was only 15%; pre-emptive transplantation was a very unusual modality. The prevalence of ESRD patients at 31 December was 693 pmp in 1996 and 827 pmp in 2001; among dialysis patients, the corresponding rates were 575 pmp and 657 pmp, respectively. Consequently, the number of dialyzed patients increased, respectively, from 28892 to 37919. The prevalent dialysis modality was bicarbonate dialysis in 74% of cases, followed by hemodiafiltration (HDF) in 15%, continuous ambulatory peritoneal dialysis (CAPD) in 7% and APD in 3%. The gross mortality rate in dialyzed patients was stable during this period, at approximately 14%, the main causes of death being cardiovascular diseases and cachexia.

[Vitamin B12 clearance (Kd-B12) in hemodialysis (HD) and hemodiafiltration (HDF)]. / La clearance della vitamina B12 (Kd-B12) in emodialisi (HD) e in emodiafiltrazione (HDF).

PURPOSE: The dialysis dose is usually assessed by Kt/V urea; however, it is possible that middle molecule (MM) removal could play a role in optimal treatment. Vitamin B12 is a classical MM marker and Kd-B12 is used to compute a MM-based dialysis index, requiring a weekly total clearance (Kd-B12 + renal creatinine clearance (CrCl) > or =30 L, corresponding to IDB12> or =1 (Babb et al, Kidney Int, 1975). Recently, it was demonstrated that by increasing the total Kd-B12 per session (TCV) from 10 to 16 and to 26 L, the relative risk (RR) of death was reduced from 1 to 0.79 and to 0.62, respectively (Leypoldt et al, Am J Kidney Dis 1999). This implies that a minimum TCV of 16 L, but preferably of 26 L per session, should be delivered, for anuric HD patients on a 3x/wk schedule. To extend these results to the whole hemodialysis (HD) population, we suggest transforming TCV into the corresponding IDB12 values: i.e. a TCV=10 L on 3x/wk corresponds to IDB12=1, a TCV=16 and 26 L corresponds to IDB12=1.6 and 2.6, respectively. METHODS: This study aimed to assess Kd-B12 and IDB12 for all stable patients in our unit. There were 62 patients (33 males, 29 females): five patients were being dialyzed once per week (1x), nine patients twice (2x), 46 patients three (3x) and two patients four times (4x) per week (wk); the session length was 232+/-18 min. Most dialyzers had a large surface area (mean 1.9+/-0.3 m2), with KoA-B12=211+/-92 mL/min. Eleven patients, 3x/wk, were on hemodiafiltration (HDF): the reinfusion rate was 33+/-3 mL/min in five patients (sHDF) and 76+/-12 mL/min in six patients (HDF on-line (OL). Kd-B12 was computed as a function of KoA-B12, effective plasma flow, Qd and ultrafiltrate (UF). IDB12 was computed from Kd-B12, ses-sion length and schedule, CrCl and body surface area. RESULTS: The main results are given below: [table: see text] On average, Kd-B12 was 105 +/- 13 mL/min on HD and 152+/-34 mL/min on HDF. A significant difference was found only for HDF-OL and was essentially due to the higher UF. Of note, the presence of renal function allowed good IDB12 values for 1x/wk and 2x/wk patients, even better than for the standard 3x/wk patients. CONCLUSIONS: We have demonstrated that most available dialyzers provide high Kd-B12 values (but HDF-OL performs significantly better) and that IDB12, by quantifying the impact of UF, session length, schedule and renal function, allows the assessment of dialysis adequacy beyond Kt/V urea, for all HD or HDF patients, on a routine basis and at no added cost.

[Regional epidemiology of chronic nephropathies: referral to nephrologist and initiation of dialysis]. / Epidemiologia regionale/locale delle nefropatie croniche: profili di "referral" ambulatoriale e inizio dialisi.

BACKGROUND: The epidemiology of pre-dialysis chronic nephropathies (CN) in well-defined contexts is essential to prevent delays in delivering appropriate care. METHODS: The registration of consecutive patients in seven out-patient and four in-patient dialysis centers of Basilicata (2001) formed a retrospective study on clinical charts and dialysis registers integrated with ad hoc data. RESULTS: Newly observed outpatients (I) numbered 328; prevalent patients (P) numbered 343. The age and gender of both I and P patients was similar (males: 60%, age media: 67 yr). In 316 I patients with creatinine (mean Cr: 2.3 mg/dL), the mean filtration rate (GFR) was 40.9 mL/min/1.73 m2: 13.6% were in advanced stage (S5) of GFR (<15 mL/min), 23.4% in S4/severe (15-29), 45.6% in S3/moderate (30-59), 10.8% in S2/mild (60-89), and 6.6% in S1 (>90). When compared to I patients, P patients had a mean GFR of 35.0 mL/min; S4+S5 was 48% (vs. 37%); hypertension 68% (vs. 58%); vasculopathies 15% (vs. 10%); coronary disease 10% (vs. 4%); erythropoietin 13% (vs. 7%); and low-protein diet 34% (vs. 20%) (p<0.01). Of 316 I patients, 117 in S5+S4 ('late referral' 37%) had a (mean) GFR of 18.4 mL/min, Cr 3.7 mg/dL, and were aged 70 yrs (vs. 64 yrs for 'early referral'). Of 53 new patients on dialysis, 26 (49%) were seen for the first time <6 months prior to starting (mean age: 71 yr vs. 62; female 58% vs. 26%; complications 50% vs. 17%). CONCLUSIONS: In this population, age-related factors are associated with late referral. Although sociodemographic variables depend on local contexts, these results are consistent with similar international studies. Social and cultural factors may influence physicians to postpone referring patients to a nephrologist, independently of clinical conditions.

[The need for integrated care of patients with chronic nephropathies: the epidemiology of 'late referral']. / Epidemiologia dei bisogni di gestione integrata: il "late referral" in Nefrologia.

BACKGROUND: The recent need for information has prompted this collaboration between health system epidemiologists (Basilicata) and clinicians to compare models of 'local' epidemiology in the management of diseases. The referral of patients to a nephrologist represents a working hypothesis of research- intervention. METHODS: Analysis of renal registry (RR) and administrative databases (hospital discharge abstracts/HDA, ambulatory);ad hoc surveys. RESULTS: Patients on dialysis between 1994 and 1998 are 594, cumulative deaths are 190 (32%). Males and the elderly (age = 65 years) are associated with more than 50% and threefold increase in relative risk of death, and with a diabetic nephropathy of 60% vs other renal diseases. Of 570 patients alive in 1996, 442 are linked with 2,628 HAD. Comorbid conditions are underreported in the RR (the Charlson index has been computed using HDA). Of 66 new dialysis cases, 31 are referred to a nephrologist only 6 months before the start of dialysis (47%) (22% diabetics). Patients discharged with chronic nephropathies (CN) and diabetes are 21% of CN patients (5% of diabetics). Of 100 patients with pre-end stage renal disease and diabetes, only 11-14 are discharged from the nephrology ward. At the local level, 3 out of 4 patients with serum creatinine higher than 1.5 mg/dl are not referred to a nephrologist. The prevalence of CN may vary from 0.4% to more than 1%. CONCLUSIONS: While an improvement in health databases in the regions is underway, collaboration studies are essential for planning specific interventions for prevention and management of diabetic nephropathy to improve the use of resources in nephrology.

Successful use of central venous catheter as permanent hemodialysis access: 84-month follow-Up in lucania.

Cuffed tunneled venous access catheters are commonly used for temporary and permanent access in hemodialysis (HD) patients. These catheters serve an essential role in providing permanent access in subjects in whom all other access options have been exhausted. The predominant complications are catheter thrombosis, catheter fibrin sheating and infection. The aim of this study was to evaluate long-term survival and complications of permanent venous catheters (PVC) placed for the purpose of HD during the period from January 1992 to December 1998, at the Dialysis Units of Lucania (a southern Italian region). A total of 98 PVC were placed in 88 patients during this period. The catheters used were of three types: (a) 72 VasCath Soft Cell catheters (Bard Instrument Company, Toronto, Ont., Canada); (b) 22 PermCath catheters (Quinton Instrument Company, Seattle, Wash., USA), and (c) 4 Tesio catheters (Bellco SpA, Mirandola, Italy). Survival curves of catheters were calculated using the Kaplan-Meier product-limit estimator. The patient survival was 60% at the 78th month. Actually, 52 patients (27 males, 25 females) are still alive: 15 (26.9%) of these patients have diabetes mellitus and 1 has been transplanted. The actuarial survival rate of PVC was 89% in the whole population studied and 82% in subjects alive after 84 months. Twenty-five patients (28.4%) had PVC as the first reliable vascular access. Long-term complications occurred 27 times (1 episode every 44.81 month/patient) as: breakage (3.1%); thrombosis (10.2%); displacement (2.0%); subcutaneous tunnel bleeding (3.1%); inadequate blood flow (7.1%), and infection (10.2%). In conclusion, our data confirm that PVC might represent an effective long-term blood access route for HD. Again, PVC are getting the access of choice for selected patients (i.e., older subjects with cardiovascular diseases and cancer patients) and are enjoying a dramatic increase in use for subjects who are terrified of repetitive venopuncture.

Jugular vein catheterization for hemodialysis: correct positioning control using real-time ultrasound guidance.

The jugular vein catheterism (JVC) is adopted for blood access in patients with acute renal failure, in chronic renal failure and when patients show failure of traditional vascular access. The technique of catheter insertion in the jugular vein is quick and easy. Usually correct catheter positioning, before starting the dialytic procedure, is controlled by chest X-ray or by intra-cavitary electrocardiogram. The aim of this work is to evaluate the feasibility of the real-time ultrasound guidance to control the correct positioning of the catheter instead of the usual chest X-ray control. We have studied 158 patients with JVC insertion before the hemodialytic procedure; 54 patients have undergone both ultrasound and a chest X-ray control while 104 were only submitted to ultrasound control. The ultrasound procedure includes an under xifoid scanning, with a convex 3.5 Mhz drill to evaluate the four heart cavities. When the right atrium is identified a second operator rapidly infuses in the venous catheter 15 ml of physiological solution thus creating a blood turbolence easily observed in real time as a light jet inside the atrium. This turbolence appears to be the main evidence for good catheter positioning and we were able to show the light jet in 156 (98%) patients. All light jet positive patients were submitted to the hemodialytic procedure without any complications during and after dialysis. We concluded that the intraoperative ultrasound control technique is an alternative to the chest X-ray evaluation because it offers the possibility for safe intraoperative immediate control thus reducing the total costs of the procedure.

The equivalent renal urea clearance: a new parameter to assess dialysis dose.

BACKGROUND: Currently the total (dialytic plus renal) urea clearance (KT) is computed as Kt/V plus the equivalent Kt/V (KT/VKR) provided by the renal urea clearance (KR). However, KT/VKR is computed with two different formulae, by Gotch and Keshaviah respectively. Moreover Teschan suggested a weekly KT, that is a multiple of Keshaviah's KT. We suggest the equivalent renal urea clearance (EKR), that kinetically quantifies the "time-averaged KT' and is independent of treatment type and schedule. METHODS: Computer simulation has been used to analyse the relationship between EKR, as corrected for urea volume (EKRc), and Kt/V. Data from 66 HD patients, of whom eight were on once-weekly and 11 on twice-weekly HD, had been used to compare EKR with current KTs. RESULTS: For each individual schedule, the relationship between EKRc and Kt/V is linear and each ml/min of KR increases EKR by the same amount. For instance, for thrice-weekly HD patients, EKRc = 1 + 10 x Kt/V: so that, the critical Kt/V values of 0.8 and 1.0 correspond to EKRc values of 9.0 and 11 ml/min respectively, independently from treatment type and schedule. As to the clinical data, all once- and twice-weekly patients had a significant KR and excellent clinical status, but most of them had 9 < or = EKRc < 11 ml/min. After appropriate reconciliation of units, it has been found that kinetic KT was overestimated by about 10-12% (range, 2-23%) by Keshaviah and Teschan's KT, and by about 2-7% (range, 0.3-15%) by Gotch's KT. CONCLUSIONS: EKRc can account for KR and provide guidelines for all types of dialysis treatments: as far as urea is concerned, dialysis adequacy should require EKRc > or = 11 ml/min. However, it is likely that EKRc > or = 9 ml/min could suffice for patients with a substantial residual renal function.

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.

A modified Two-BUN method for routine urea modeling: clinical validation in 120 patients on a free diet.

Recently, a modified algorithm of the Two-BUN method (MA2p), avoiding dialyzer clearance measurement, was presented for routine assessment of Kt/V and NPCR. To validate MA2p in patients on a free diet (FDP), we studied 120 stable dialysis FDP by measuring Kt/V and NPCR with both MA2p and a modified version of the standard Three-BUN method (MA3p), for the 3 weekly sessions. The NPCR values (g/kg/day), calculated by MA3p for the 3 interdialyses were: 1.286 +/- 0.274, 1.256 +/- 0.276, and 1.116 +/- 0.230, respectively. The correlation coefficient (r) for averaged Kt/V values obtained by the two methods was 0.999 and the percent error (Error%) for MA2p vs. MA3p results ranged from -1.5 to +0.78%. The respective results for NPCR were: r = 0.967, Error% range from -11.7 to +13.9%. In conclusion, MA2p can be safely used in patients on a free diet. The lowest NPCR values were observed during the long interdialysis.

Reconciliation between urea kinetics and direct dialysis quantification.

Previous studies comparing urea kinetic model (UKM) and direct dialysate quantification technique (DDQ) found statistically different results as far as the urea distribution volume (V) and protein catabolic rate (PCR) are concerned. In these studies, however, the true values for both the dialyser urea clearance (K) and urea concentration (C) were not used. The aim of this study was to compare UKM and DDQ using for both methods a variable-volume single-pool (VVSP) model as well as plasma water C and effective K. The study was performed during paired filtration dialysis (PFD) sessions because this technique allows bloodless measuring of K. Twenty dialysis patients were studied during a single PFD session. Dialysate and ultrafiltrate C and urea mass transfer rate were measured every 15 min to compute averaged K and total urea removal. Blood samples were obtained as for a three-point UKM, and an iterative technique was used for both methods. The results (means +/- SD) obtained with UKM were as follows: K = 176 +/- 23 ml/min; V = 29986 +/- 7620 ml, PCR = 65 +/- 15 g/day, Kt/V = 1.04 +/- 0.17. These results were not statistically different from those obtained using DDQ. In conclusion, when methodological errors are avoided, DDQ and UKM provide very similar results. This study shows also that PFD is very useful for studying solute kinetics during dialysis.

Percent reduction in blood urea concentration during dialysis estimates Kt/V in a simple and accurate way.

Urea Kt/V is an accurate tool to estimate the adequacy of hemodialysis (HD) therapy; however, the current methods of calculating Kt/V are too complex for routine clinical use and require great care in order to avoid major inaccuracies. As percent reduction in blood urea concentration during dialysis (PRU) is a function of dialyzer urea clearance, length of dialysis, and urea distribution volume of the patient, it might correlate with Kt/V. Thus, analyzing retrospectively data of 78 studies, we found that the following linear regression equation existed between Kt/V values calculated by means of direct dialysis quantification (DDQ) and PRU values: Kt/V = 0.023 x PRU - 0.284 (r = 0.92). Furthermore, a good correlation existed between Kt/V values measured both by means of DDQ and of the classical algorithm (CA) of the urea kinetic model (UKM) (r = 0.98). Then, a prospective study was started in which 145 Kt/V values calculated by means of the above equation were correlated with the corresponding ones computed by means of a modified algorithm (MA) of UKM, perfectly fitting those generated by CA of UKM. Although the relationship was exponential, it was linear in the clinically important range of PRU between 40% and 70%, corresponding to a Kt/V between 0.64 and 1.33. Furthermore, an excellent correlation (r = 0.96) and no statistically significant difference existed in this range between the two series.(ABSTRACT TRUNCATED AT 250 WORDS)