[Assessment of reticulocyte hemoglobin content as a guide for iron supplementation in hemodialyzed patients]. / Valutazione del contenuto emoglobinico reticolocitario (CHr) come guida alla supplementazione marziale nei pazienti emodializzati.

BACKGROUND: In literature the reliability of reticulocyte hemoglobin content (CHr) has been recently emphasized to detect "functional" iron deficiency induced by erythropoietin therapy. METHODS: In the present work the behavior of CHr in 68 uremic patients hemodialysis has been evaluated. RESULTS: Its values appeared poorly correlated (R2 = 0.32) to the hypochromic erythrocyte percent values, and furthermore CHr sensitivity seemed poor, with pathologic low values detected in three cases only, all characterized by reduced mean corpuscular volume (MCV). CONCLUSIONS: In the cases personally observed, MCV and CHr are weakly correlated (R2 = 0.15); reticulocyte hemoglobin absolute value in personal opinion does not appear as a reliable index of iron deficiency, being rather dependent on reticulocyte volume.

Measurement of vascular access recirculation unaffected by cardiopulmonary recirculation: evaluation of an ultrasound method.

Recently developed devices provide detection of access recirculation (AR) and cardiopulmonary recirculation (CPR) by optical, thermal, conducimetrical, and ultrasound methods (USM). We evaluated the last one both in vitro reproducing AR by a bypass pump and in vivo. In vitro, the USM sensitivity was about 5%. In vivo, the USM was compared with the traditional urea method (UM) in 69 patients. 8.7% of the cases resulted positive by both UM and USM. One case was USM positive and UM negative. The UM sensitivity threshold was 6-10%. The accuracy (in vitro) and the repeatability (in vivo) of the USM were satisfactory. USM clearly distinguished AR from CPR. In conclusion, AR determination by USM, avoiding misleading interferences with CPR, is a rapid, easy, and noninvasive method to routinely exclude a potential cause of reduced dialytic efficiency.

Cefonicid 'restores' the depressed activities of polymorphonuclear cells from chronic haemodialysis patients and renal transplant recipients in vitro.

BACKGROUND: Chronic haemodialysis patients and renal transplant recipients are highly susceptible to infection characterized by high morbidity and mortality and related to an impairment of the phagocytic response. SUBJECTS AND METHODS: In order to elucidate how cefonicid, a cephalosporin with a broad spectrum of activity and once-daily dosage, influences this phagocytic response, the effects of the drug upon the functions of human PMNs from both healthy individuals and immunocompromised patients were investigated. RESULTS: In vitro, PMNs from haemodialysed patients and renal transplant recipients showed a diminished phagocytic efficiency with reduced phagocytosis and bactericidal activity towards intracellular Klebsiella pneumoniae when compared with that seen in PMNs from healthy subjects. Cefonicid significantly affected the activity of PMNs from healthy volunteers, resulting in either an increased percentage of ingested klebsiellae or a reduced intracellular bacterial load when compared with the control, drug-free system. When cefonicid was added to PMNs from uraemic patients a pattern similar to that observed with phagocytes from healthy subjects was detected: the antibiotic was able to 'restore' the depressed primary functions of PMNs, resulting in a significant increase in both phagocytosis and killing activity. CONCLUSIONS: Cefonicid, with its several immunoproperties observed in this study, possesses interesting beneficial properties which make it suitable for the treatment of infections in patients with impaired components of the immune system.

[Estimation of total body water from routine urea kinetics]. / La stima dell'acqua corporea totale per la cinetica dell'urea di routine.

The comparison of total body water obtained by Watson formula with results of bioelectrical impedance (BIA) shows a fair approximation (Delta% = 1.0 +/- 8.45). However, when compared to other literature formulas the BIA values are higher (8 divided by 23%), and this discrepancy needs further analysis. Urea kinetics was computed using as input data for distribution volume both the Watson anthropometrical and the BIA TBW values: the clearance results do not differ significantly (Delta% = 0.74 +/- 8.35). The Kt/V index results are nearly identical (Delta% = 0.12 +/- 1.17), due to a mathematical loop: a wrong input of volume induces a comparable error of the clearance result, while their ratio is unchanged. For practical routine to monitoring dialysis adequacy the Watson anthropometrical formula has proven as a satisfactory simple approach. Periodical BIA determination provides useful informations mainly when the anthropometrical estimation are doubtful and the comparison of data may increase the kinetic reliability.

[Proposal of new formulas for three-point urea kinetics, compared with traditional kinetics and direct dialysis quantification]. / Proposta di nuove formule per la cinetica dell'urea a tre punti, a confronto con la cinetica tradizionale (UKM) e con la quantificazione diretta della dialisi (DDQ).

Classical urea kinetic model (UKM) has been followed by several proposals to determine dialysis adequacy either by direct quantification (DDQ), either by simplified two-points formulas (pre- and post-dialysis BUN), or by mUKM, a modified three-point algorithm (pre-post and pre-next dialysis), where urea distribution volume is input to obtain clearance and urea generation rate. Our new formulas (mUKM2) are derived from urea mass balance, and avoid iterative calculation: their results are similar to those obtained by UKM and mUKM when the standard post-dialysis BUN value is employed. On the contrary, when the equilibrated net-rebound value (Cpwnr) is employed their results are very close to the reference DDQ model: however the new approach is simpler and more practical, to measure dialysis dose taking account of the urea rebound phenomenon.

Agreement between the classical urea kinetic model and direct dialysis quantification: importance of urea rebound.

From a review of the literature regarding kinetic models used for assessing the adequacy of hemodialysis, no definite conclusions can be drawn as to whether the classical urea kinetic model (UKM) or modified direct dialysis quantification (mDDQ) is more reliable. We compared mDDQ with classical UKM and with a modified UKM that employs an equilibrated urea value. From the theoretical viewpoint, no substantial conflict is found between the two models as regards the dialysis dose, if urea rebound is considered. From the practical viewpoint, in our opinion direct quantification lends itself better for experimental purposes whereas for routine Kt/V evaluation UKM is easier and accurate enough, provided that rebound is taken into account.

On-line dialysate urea monitor: comparison with urea kinetics.

The outputs of a new on-line dialysate urea monitor (UM) were compared to a urea kinetic model (UKM) and to dialysis direct quantification (DDQ) in 13 patients. As for urea extraction and predialysis urea level, a good degree of correspondence was found between UM and laboratory data. Kt/VUM (1.21) is intermediate between Kt/VUKM (1.28) and Kt/VUKM using the post-rebound urea value (1.14) or Kt/VDDQ (1.14). Passing and Bablok regression analysis indicated no systematic error between Kt/VUM and Kt/VDDQ. The percentage differences in nPCR by UM, UKM and DDQ were not significant, but the standard deviations were wide. The UM approach is very simple and practical, avoiding blood sampling, laboratory analysis and data handling. It is reliable enough for clinical practice. Compared with traditional urea kinetics, Kt/V computation by a mathematical elaboration of the dialysate urea profile drawn from several points theoretically invites fewer errors due to the analytical procedure.

Comparison of a modified urea kinetic model direct dialysis quantification and classic urea kinetic modeling.

In the classic urea kinetic model (UkM), the measurement of clearance (K) as a model input is onerous, and its result is higher than actual body clearance because of urea disequilibrium. Urea kinetics performed by direct dialysis quantification (DDQ), with an equilibrated post rebound sample, gives reliable results but is routinely impractical. The modified UKM (mUKM) method is based on the input of urea distribution volume (V), easily obtainable by several methods and more stable than clearance, and uses simple formulae derived from urea mass balance, avoiding iterative computation. Compared with DDQ, mUKM results are identical, provided that the V value obtained by DDQ is used as input. Compared with UKM, mUKM urea clearances are significantly lower (158.1 +/- 20.5 versus 180.7 +/- 26.8 ml/min), as are urea nitrogen generation rates (5.85 +/- 2.0 versus 6.41 +/- 2.14 mg/min), whereas V results are close (32,444 +/- 6301 versus 32,141 +/- 5293 ml): consequently, mUKM Kt/V is significantly lower than UKM Kt/V (1.07 +/- 0.17 versus 1.22 +/- 0.18). This is because both mUKM and DDQ take account of post dialysis urea rebound. Therefore, if UKM formulae are used with the DDQ body clearance and the equilibrated post rebound blood urea nitrogen value as input data, their results strictly approximate the reference DDQ (V = 32,457 +/- 6274; Kt/V = 1.07 +/- 0.17; G = 5.85 +/- 2.0), demonstrating the common mathematical basis of DDQ and UKM. Therefore, reliable results may be obtained by DDQ, by mUKM, and by "equilibrated" UKM; we suggest that the mUKM model, less cumbersome than DDQ, and more reliable than UKM because it avoids the clearance measurement and the need for iterative computation, could be useful for routine kinetics.

Accuracy of an on-line urea monitor compared with urea kinetic model and direct dialysis quantification.

To verify the accuracy of a urea monitor (UM) to assess dialysis adequacy, it was compared with a modified direct dialysis quantification method (mDDQ) and with a Casino modified urea kinetic model (mUKM) algorithm. Simplified Jindal and Daugirdas formulas, an anthropometric body water Watson formula, bioelectric impedance analysis, and the Garred model have also been considered. Concerning urea removal, UM results are close to mDDQ, as are the predialytic blood urea nitrogen values obtained by UM in the initial equilibration test. Urea distribution volume results for UM, mDDQ, and bioelectric impedance analysis are similar, whereas it appears clearly overestimated by the Watson formula. Urea monitor clearances are not significantly different from mDDQ, unlike UM Kt/V, which is slightly higher than mDDQ reference value, although with a satisfactory degree of concordance. Rebound effect must be considered by sampling after the equilibration time (et) when mUKM or simplified Kt/V formulas are used: mUKMet Kt/V results are quite similar to mDDQ, as is the Daugirdas value. Regarding NPCR, UM results are neither significantly different from mDDQ nor from the Garred model, whereas mUKM results are significantly overestimated. When rebound is considered, NPCR by mUKMet and NCPR by mDDQ are identical. The UM approach is simple and practical, with a satisfactory degree of reliability for clinical practice.

[Quantification of treatment time in the high-efficiency dialysis method]. / Quantificazione dei tempi di trattamento nelle metodiche di dialisi ad alta efficienza.

Precise quantification of treatment time is allowed by using the urea kinetic models for dialytic therapy prescription: the dialytic dose may be expressed by the KT/V ratio, the nutritional status by PCR. Due to dialysis disequilibrium urea extraction was significantly lower in high efficiency dialysis than in traditional schedules, suggesting to increase the KT/V value when treatment time is reduced. The comparison of KT/V and PCR values obtained by the Gotch model (single pool variable volume) with the results derived by the diagram of Keshaviah has shown significant correlation for both, confirming the usefulness of this simplified model in clinical practice.

Scant reliability of Co/Ct ratio in urea kinetic formulas.

The ratio initial/final urea value is used in urea kinetic formulas. To assess its reliability we employed mass balances and urea clearances to study 15 hemodialysis treatments divided in several parts. The mass balances clearly indicated urea disequilibrium. In the first phases of dialysis, urea extraction, measured by dialysate collection, was lower than the corresponding change in urea pool, whereas in the later phases the opposite occurred. On account of this lack of equilibrium, clearances bases on the Co/Ct ratio (K2) are less reliable than standard clearances derived from total dialysate collection (K1): in the first quarter of dialysis, K2 is greater than K1 (p less than 0.01), while in the 3rd and 4th quarters it is lower. The comparison of clearances in a cumulative way showed a significant fall in K2 (p less than 0.01) while K1 remained stable. From a practical point of view, aberrations induced by non monocompartmental urea behaviour are negligible, and do not invalidate the usefulness of the single-pool Gotch model in clinical practice. However, at least in experimental work, the limits of urea kinetic formulas must be taken into account.

The immunological state in chronic renal insufficiency.

To evaluate the immunological state in chronic renal insufficiency, the Authors studied cellular and humoral immunity in 292 patients with chronic renal failure. They were divided into 3 groups: 1) 37 with creatinine clearance between 50 and 20 ml/min; 2) 57 with creatinine clearance between 20 and 8 ml/min; 3) 178 treated by hemodialysis. In vivo and in vitro tests, that is DNCB, PPD skin tests, spontaneous, active and EAC rosettes, surface membrane immunoglobulin test, complement (C3, C4) and serum immunoglobulins were taken as markers of the immune response. Cell-mediated immunity was found to be significantly impaired in patients with terminal renal insufficiency or on hemodialysis and also markedly reduced in patients with non-terminal renal insufficiency. Humoral immunity produced less significant results: the B lymphocyte count and serum immunoglobulins were normal; only C3 levels were found below normal range. Thus it would seem that cell-mediated immunodeficiency appears in an early stage of chronic renal failure and that hemodialysis does not improve this deficiency.

Clinical significance of the detection of circulating immune complexes in lupus nephritis.

32 patients (22 biopsed) with lupus nephritis (LN) were observed for circulating immune complexes (IC). Solid phase C1q (SPC1q) and polyethylene glycol (PEG) precipitation tests were used. The patients were studied during the clinical follow-up in different phases of disease activity. Comparative studies between each histological class of LN and corresponding forms of idiopathic glomerulonephritis (IGN) were made: no significant differences were found between either mesangial LN and stalk mesangial IGN, or between focal proliferative LN an focal proliferative IGN. However, a significant difference was found for SPC1q data between diffuse proliferative LN and mesangiocapillary IGN, and between membranous LN and membranous IGN. LN, with an acute nephritic syndrome and hypocomplementemia, displayed SPC1q data significantly above the levels of IC found in IGN with similar clinical features. IC serum data would seem an important element for the diagnosis and the clinical management of patients affected by LN.

[Regular dialytic treatment in the Piedmont region. Results and prospects]. / Trattamento dialitico regolare nella Regione Piemonte Risultati e prospettive.

The Piedmont planning for the prevention and treatment of chronic uremia started in 1976, with the purpose to extending full treatment of the whole region, through the development of home and self care dialysis and intensive use of hospital short dialysis. Hospital dialysis would be reserved either for new treatments or complicated or uncooperative patients. Thank to an intensive exploitation of the existing hospital centers, a 68.7% increment in the number of treated patients was achieved and costs were kept down to a limited acceptable range. With the development of home and self care dialysis, 27% of the patients were located in out-of-hospital centers, and 17% at home. The Piedmont planning concerned itself with the patients' data collected by the Regional Registry under the following items: a) characteristics of dialysis population; b) the present modes of treatment; c) the number of patients apt to varying treatments and renal transplantation; d) the epidemiology of uremia causing nephropathies. At the present time results are only preliminary. Nevertheless, the first observations showed a long and difficult work with good possibilities of success for computerized facilities in the field of dialysis, particularly in respect to regional areas which in the reformed Health Service are now considered to be operating as autonomous.