¿Mejora la aproximación físico-química de Stewart-Fencl la valoración del equilibrio ácido-base en pacientes estables en hemodiafiltración? / Does Stewart-Fencl approach improve the evaluation of acidbase status in stable patients on hemodiafiltration?

Introducción: la evaluación del equilibrio ácido-base se basa en la ecuación de Henderson-Hasselbach. En 1983, P. Stewart desarrolló un análisis cuantitativo del equilibrio ácido-base en el que muestra un sistema con unas variables independientes entre las que se incluyen pCO2, diferencia iónica fuerte medida (SIDm), es decir, la diferencia entre la suma de cationes fuertes (Na+, K+, Ca++, Mg++) y la suma de aniones fuertes (Cl–, lactato) y la concentración total de todos los aniones débiles no volátiles (ATot), cuyos principales representantes son el fósforo inorgánico (P–) y la albúmina (Albúm.–). El objetivo de este estudio es evaluar desde ambas perspectivas el equilibrio ácido-base en pacientes en hemodiafiltración (HDF) crónica. Material y métodos: se estudian 35 pacientes (24 hombres y 11 mujeres, con una edad media de 67,2 ± 15,7 años y con un peso seco de 72,8 ± 19,2 kg. La duración media de la hemodiálisis (HD) fue de 253,6 ± 40,5 minutos. Se analizan los parámetros gasométricos (pH, pCO2, HCO3–y exceso de bases) y Na+, K+, Cl–, Ca++, Mg++ y lactato. Se calcularon la SIDm, la SIDe mediante la fórmula de Figge (1.000 x 2,46–11 x pCO2 /[10 – pH] + Albúm. g/dl x [0,123 x pH –0,631] + P en mmol/l x [0,309 x pH –0,469)] y gap del SID (SIDm-SIDe). Resultados: el pH pre-HD fue de 7,36 ± 0,08 y el pH post-HD de 7,44 ± 0,08 (p <0,001). No se apreciaron diferencias significativas entre pCO2 pre y post-HD. El HCO3 – y el exceso de bases se incrementaron durante la sesión (p <0,001). La SIDm descendió de manera significativa de 46,2 ± 2,9 preHD a 45 ± 2,3 post-HD (p <0,05). Por el contrario, la SIDe se elevó de 38,5 ± 3,8 a 42,9 ± 3,1 (p <0,001). El anion gap descendió de 18,6 ± 3,8 pre-HD a 12,8 ± 2,8 Eq/l post-HD (p <0,001) y el gap del SID de 7,6 ± 3 a 2,1 ± 2 (p <0,001). Se apreció una correlación entre el anion gap y el gap-SID tanto antes como después de la HDF. Asimismo, se apreció una correlación significativa entre el ?? exceso de bases y ?? del gap-SID. Conclusión: en conclusión, la aproximación físico-química de Stewart-Fencl no mejora la valoración del equilibrio ácido-base en pacientes en HDF crónica. En presencia de normocloremia la SIDm no refleja el proceso alcalinizante de la sesión de hemodiálisis. Bajo esta perspectiva, la sesión de hemodiálisis se concibe como una retirada de aniones inorgánicos no metabolizables, en especial el sulfato. El espacio dejado por estos aniones es reemplazado por OH–y secundariamente por HCO3–. La única ventaja vendría dada por una mejor valoración de los aniones no medidos mediante el gap del SID, sin el efecto de la albúmina y el fosfato (AU)

Introduction: The traditional evaluation of acid-base status relies on the Henderson-Hasselbach equation. In 1983, an alternative approach, based on physical and chemical principles was proposed by P. Stewart. In this approach, plasma pH is determined by 3 independent variables: pCO2, Strong Ion Difference (SIDm), which is the difference between the strong cations (Na+, K+, Ca++, Mg++) and the strong anions (Cl–, lactate) and total plasma concentration of nonvolatile weak acids (ATot), mainly inorganic phosphate and albumin. Bicarbonate is considered a dependent variable. The aim of this study was to evaluate the acid-base status using both perspectives, physical chemical and traditional approach. Material and methods: we studied 35 patients (24 male; 11 female) on hemodiafiltration, mean age was 67.2 ± 15.7, 8 ± 19.2 kg. We analyzed plasma chemistry including pH, pCO2, HCO3–, base excess and Na+, K+, Cl–, Ca++, Mg++, lactate and SIDm. The SID estimated (SIDe) was calculated by Figge’s formula (1,000 x 2.46–11 x pCO2/[10 – pH] + Album g/dl x [0.123 x pH –0.631] + P in mmol/l0 x [0.309 x pH –0.469]) and Gap of the SID as the difference SIDm-SIDe. Results: pH preHD was 7.36 ± 0.08 and pH post-HD 7.44 ± 0.08 (p <0.001). There was no significant differences between pCO2 pre- and post-HD. HCO3– and base excess increased during the session (p <0.001). SIDm decreased from 46.2 ± 2.9 pre-HD to 45 ± 2.3 mEq/l post-HD (p <0.05). On the opposite, SIDe increased from 38.5 ± 3.8 to 429 ± 3.1 mEq/l (p <0.001). The Gap Anion descended from 18.6 ± 3.8 pre-HD to 12.8 ± 2.8 mEq/l post-HD (p <0.001) and the Gap of the SID 7.6 ± 3 to 2.1 ± 2 (p <0.001). Anion Gap correlated with the Gap-SID so much pre-HDF as pos-HDF. ?? Base excess correlated only with ?? of the Gap SID. Conclusion: Stewart-Fencl’s approach does not improve characterization of acid-base status in patients on chronic HDF. In presence of normocloremia the SIDm does not reflect the alkalinizing process of the session of hemodialysis. According this approach, hemodialysis therapy can be viewed as a withdrawal of inorganic anions, especially the sulphate. These anions are replaced by OH– and secondarily for HCO3–. The approach only improves the evaluation of unmeasured anions by the Gap of the SID, without the effect of albumin and phosphate (AU)

[Does Stewart-Fencl improve the evaluation of acid-base status in stable patients on hemodiafiltration?]. / ¿Mejora la aproximación físico-química de Stewart-Fencl la valoración del equilibrio ácido-base en pacientes estables en hemodiafiltración?

INTRODUCTION: The traditional evaluation of acid-base status relies on the Henderson-Hasselbach equation. In 1983, an alternative approach, based on physical and chemical principles was proposed by P. Stewart. In this approach, plasma pH is determined by 3 independent variables: pCO2, Strong Ion Difference (SIDm), which is the difference between the strong cations (Na +, K +, Ca ++, Mg ++) and the strong anions (Cl-, lactate) and total plasma concentration of nonvolatile weak acids (ATot), mainly inorganic phosphate and albumin. Bicarbonate is considered a dependent variable. The aim of this study was to evaluate the acid-base status using both perspectives, physical chemical and traditional approach. MATERIAL AND METHODS: We studied 35 patients (24 M; 11F) on hemodiafiltration, mean age was 67,2+/-15,7, 8+/-19,2 kg. We analyzed plasma chemistry including pH, pCO2, HCO3-, base excess and Na+, K+, Cl-, Ca++, Mg++, lactate and SIDm. The SID estimated (SIDe) was calculated by Figge's formula (1000 x 2.46E-11 x pCO2 / (10-pH) + Album gr/dl x (0.123 x pH-0.631) + P in mmol/l x (0.309 x pH-0.469) and Gap of the SID as the difference SIDm-SIDe. RESULTS: pH preHD was 7,36+/-0,08 and pH posHD 7,44+/-0,08 (p < 0.001). There was no significant differences between pCO2 pre and pos-HD. HCO3 - and base excess increased during the session (p < 0.001). SIDm decreased from 46,2+/-2,9 preHD to 45+/-2,3 mEq/l postHD (p < 0.05). On the opposite, SIDe increased from 38,5+/-3,8 to 42,9+/-3,1 mEq/l (p < 0.001). The Gap Anion descended from 18,6+/-3,8 preHD to 12,8+/-2,8 mEq/l mEq/l postHD (p < 0.001) and the Gap of the SID 7,6+/-3 to 2,1+/-2 (p < 0.001). Anion Gap correlated with the Gap-SID so much pre-HDF as pos-HDF. Delta Base excess correlated only with Delta of the Gap SID. CONCLUSION: Stewart-Fencl's approach does not improve characterization of acid-base status in patients on chronic HDF. In presence of normocloremia the SIDm does not reflect the alkalinizing process of the session of hemodialysis. According this approach, hemodialysis therapy can be viewed as a withdrawal of inorganic anions, especially the sulphate. These anions are replaced by OH - and secondarily for HCO3-. The approach only improves the evaluation of unmeasured anions by the Gap of the SID, without the effect of albumin and phosphate.

[Kinetic of calcium, phosphate, magnesium and PTH variations during hemodiafiltration]. / Cinéica del calcio, fósforo, magnesio y variaciones de la parathormona (PTH) en pacientes en hemodiafiltracion.

Hemodiafiltration (HDF) is a technique resulting from coupling of diffusive and convective transport and thereby increase the elimination of small and middle molecules. However, may induce a convective loss from others substances such as calcium and magnesium. The aim of this study was to evaluate the effects of Ultrafiltration on the kinetics of calcium, phosphate, magnesium and parathyroid hormone. A total of thirteen patients (7 males and 6 females) on hemodialysis, were studied. Each patient was randomly dialyzed with the same dialysate calcium concentration and three different ultrafiltration rate. Schedule A: High flux hemodialysis, schedule B: HDF with 10% of weight body and schedule C: HDF with 20% of weight body. The others parameters were kept identical. Total Ultrafiltration was 2,6+/-0,9 L (9,78+/-3,78 ml/min) in A, 9,3+/-1,7 L (34,54+/-6,22 ml/min) in B and 16,3+/-3,3 L (60,94+/-12,63 ml/min) in C. Replacement fluid during dialysis was 6,85+/-1,42 and 13,65+/-2,9 L. in C and C respectively. Postdialysis total,ionized calcium and magnesium were significantly lower in schedules B and C versus A. PTH levels did not differ significantly. However, PTH changes during dialysis was -36.6+/-38.6%, 6.3+/-69.8% and 32.2+/-63.2% in A, B and C, respectively (p<0.05 A vs. C). A significant inverse correlation was found between total Ultrafiltration and postdialysis levels of total calcium (r:-0.56, p<0.001), ionized calcium (r:-0.65, p<0.001) and magnesium (r:-0.47, p<0.01). No differences were observed in pre and postdialysis phosphate levels, neither mass transfer and clearance of phosphate. We concluded that high ultrafiltration flow rates and substitution fluid without divalent cations induces a negative calcium and magnesium balance. These changes may stimulate PTH secretion during HDF. This technique did not resulted in a higher clearance or phosphate removal.

[Oxidative stress analysis in patients on hemodiafiltration on-line]. / Análisis del estrés oxidativo en pacientes en hemodiafiltración en línea.

Patients with chronic renal disease have a very high mortality due to cardiovascular disease. However, the traditional risk factors are not the only one explanation. Nowadays, there are new risk factors becoming, and one of these is the oxidative stress. Besides today we know that when these patients receive haemodialysis are being exposed to an additional oxidative stress. The aim of this study was to measure and to compare the degree of oxidative stress in two groups of patients on different dialysis techniques: a) On-Line Haemodiafiltration three times / week (OL-HDF). b) Daily Om-Line haemodiafiltration ( six times / week ) ( dOL-HDF) We studied 9 patients with chronic renal disease stage 5 on hemodialysis. They all were men, with a medium age of 72,5 +/- 6 years. Five patients were on dOL-HDFand four on tOL-HDF. Glutathione (GSH) concentration of patients on dOL-HDF before dialysis was 742+/- 153 nmol/ml and post-dialysis de 878+/- 223. Blood GSSG concentration before and after dialysis was 34+/- 14 nmol/ml y 137+/- 74 nmol/ml (p< 0,03). GSSG/GSH ratio pre-dialysis was 58+/-10 and post-dialysis 169+/-65 ( p < 0,03). In OL-HDF group GSSG concentration and the ratio GSSG/GSH also increased in a significative way from 99+/-45 nmol/ml to 179+/-66 nmol/ml, and from 161+/- 99 to 337+/-143 ( p<0,05). We also found differences in pCR concentrations between both groups; 3+/-1,4 g/l in dOL-HDF and 8,75+/-5,8 g/l in HDF OL. (p< 0,05). We did not find differences between xatine-oxidase activity before and after hemodialysis and between groups. In conclusion, patient with terminal chronic renal disease on OL-HDF receive an additional load of oxidative stress, as the increase in GSSG/GSH ratio in both groups shows. However patients on dHDF-OL shows low ratios GSSG/GSH post-hemodialysis and low pCR concentrations, and maybe this could be explained because daily on line haemodiafiltration improves purification of inflammatory mediators. Clue words: Hemodialysis, oxidative stress, glutathione, gssg/gsh ratio, xantine oxidasa.

[Middle molecules removal. Beyond beta2-microglobulin]. / Depuración de grandes moléculas. Más allá de la beta2-microglobulina.

The uremic toxin removal capacity mainly depends on dialyzer and hemodialysis modes. The low-flux hemodialysis only removes solutes having molecular weights less than 5.000 Da. High-flux hemodyalisis represents a form of low-volume hemodiafiltration because of the internal filtration and back-filtration that can take place within a dialyzer. Hemodiafiltration with large volumes of replacement fluid seems to be the best technique for removing all small, medium-sized and large molecules. The objective of our study was to evaluate the large molecules removal bigger than beta2-microglobuline on high flux haemodialysis and on-line hemodiafiltration with postdilutional infusion, in patients with three times a week dialysis and on short daily dialysis. We studied 24 patients, 15 males and 9 females stable on haemodialysis programme, twelve on standard four to five hours three times a week dialysis and twelve on 2 to 2 1/2 hours six times a week dialysis. All patients were dialysed with Fresenius 4008 monitor, three sessions on high flux haemodialysis (HD) and three sessions on on-line hemodiafiltration (OL-HDF). Two sessions with each filter were performed (polisulfone HF80, polyethersulfone Arylane H9 and new polisulfone APS 900). Pre and postdialysis concentrations of urea, creatinine, (beta2-microglobulin (beta2-m), myoglobin, prolactin and alpha1 microglobulin (alpha1-m) were measured. There was no difference in urea and creatinine small molecules removal. beta2m removal was 68% on HD and 81% on OL-HDF. Myoglobin and prolactin present a similar removal pattern, a higher removal with new filters (60% with Arylane and 59% with APS) in comparison with clasical polisulfone (22% with HF80). The mean alpha1-m reduction rate on HD was 6% and on OL-HDF 22%. OL-HDF with APS 900 filter was the most remove technique (35.4%), significatively higher than the other modes and filters. We can conclude that the new filters generation reach a better uremic toxins removal, specially in large molecules higher than beta2-m and on HD modality.

[Determination of the dose of dialysis with integrated modules in the same monitor]. / Medición de la dosis de diálisis mediante diferentes módulos integrados en un mismo monitor.

The "gold standard" method to measure the mass balance achieved during dialysis for a given solute is based on the total dialysate collection. This procedure is unfeasible and too cumbersome. For this reason, alternative methods have been proposed including the urea kinetic modelling (Kt/V), the measurement of effective ionic dialysance (Diascan), and the continuous spent sampling of dialysate (Quantiscan). The aim of this study was to compare the reliability and agreement of these two methods with the formulas proposed by the urea kinetic modelling for measuring the dialysis dose and others haemodialysis parameters. We studied 20 stable patients (16 men/4 women) dialyzed with a monitor equipped with the modules Diascan (DC) and Quantiscan (QC) (Integra. Hospal). The urea distribution volume (VD) was determined using anthropometric data (Watson equation) and QC data. Kt/V value was calculated according to Daurgidas 2nd generation formula corrected for the rebound (eKt/V), and using DC (Kt/VDC) and QC (Kt/VQC) data. The total mass of urea removed was calculated as 37,93 +/- 16 g/session. The VD calculated using Watson equation was 35.7 +/- 6.6 and the VDQC was 35.06 +/- 9.9. And they showed an significative correlation (r:0,82 p < 0.001). The (VDQC-VDWatson) difference was -0.64 +/- 5.8L (ns). Kt/VDC was equivalent to those of eKt/V (1.64 +/- 0.33 and 1.61 +/- 0.26, mean difference -0.02 +/- 0.29). However, Kt/VQC value was higher than eKt/V (1.67 +/- 0.22 and 1.61 +/- 0.26 mean difference 0.06 +/- 0.07 p < 0.01). Both values correlated highly (R2: 0.92 p < 0.001). Urea generation (C) calculated using UCM was 8.75 +/- 3.4 g/24 h and those calculated using QC was 8.64 +/- 3.21 g/24 h. Mean difference 0.10 +/- 1.14 (ns). G calculated by UCM correlated highly with that derived from QC (R2: 0.88 p < 0.001). In conclusion, Kt/VDC and Kt/VQC should be considered as valid measures for dialysis efficiency. However, the limits of agreement between Kt/VQC and eKt/V were closer than Kt/VDC.

Medición de la dosis de diálisis mediante diferentes módulos integrados en un mismo monitor / Determination of the dose of dialysis with integrated modules in the same monitor

La recolección total del líquido de diálisis para cuantificar la cantidad total deurea eliminada durante la hemodiálisis (HD) se ha considerado la técnica «goldestándar» para medir la dosis de diálisis. Dada la dificultad de este método sehan propuesto otros alternativos como el modelo cinético de la Urea (Kt/V), lamedición de la dialisancia iónica o la recogida de muestras representativas del líquidode diálisis total.El objetivo de este trabajo es comparar la fiabilidad y concordancia de dos dispositivosde medida (dialisancia iónica y recogida parcial de líquido de diálisis)integrados en el mismo monitor de diálisis y compararlos con los propuestos porel modela cinético de la urea (MCU) para la medición de la dosis de diálisis(Kt/V) y otros parámetros de HD.Para ello se estudiaron 20 pacientes (16V/4M) con una edad media de 64,5 ±13 años, estables en programa de HD y dializados con el monitor Integra® (Hospal)equipado con los biosensores Diascan (DC) y Quantiscan (QC). El volumende distribución de urea (VD) se calculó a partir de la fórmula de Watson y porel QC. La generación de urea se calculó a partir del MCU y el Kt/V se determinópor la fórmula de Daurgidas 2ª generación corregida para el rebote (eKt/V),por el DC y el QC.La transferencia de masa de urea medida por QC fue de 37,2 ± 13,8 g. El VDpor la fórmula de Watson y por QC fue de 35,7 ± 6,6 y de 35,06 ± 9,9 L respectivamente(ns) y mostraron una correlación significativa (r: 0,82 p < 0,001).Los valores de aclaramiento (K), mediante DC, y QC fueron similares KQC: 230,3± 56,5 ml/min, KDC: 214,05 ± 24,3 ml/min (ns) No se apreciaron diferencias enel Kt/V calculado por DC y el eKt/V (KtVDC: 1,64 ± 0,33 vs KtVeq; 1,61 ± 0,26).El coeficiente de correlación fue de r: 0,45 (p < 0,05). Por el contrario los valoresde Kt/VQC fueron superiores a los calculados por el eKtV (1,67± 0,22 vs. 1,61± 0,26). El coeficiente de correlación fue de r: 0,94 ( p < 0,001). La generaciónde urea por el MCU fue de 8,7 ± 3,4 y por QC de 8,6 ± 3,2 g/ 24h (ns) r: 0,94p < 0,001).Podemos concluir que tanto la medición de la dialisancia iónica mediante elDC, como la recogida de muestras representativas del líquido de diálisis medianteel QC, son métodos sencillos, fiables y reproducibles que nos permiten medirde manera rápida la eficacia dialítica y otros parámetros de hemodiálisis. En nuestra experiencia la cuantificación de la dosis de diálisis mediante el QC presentauna mayor concordancia que la realizada con DC

The «gold standard» method to measure the mass balance achieved during dialysisfor a given solute is based on the total dialysate collection. This procedure isunfeasible and too cumbersome. For this reason, alternative methods have beenproposed including the urea kinetic modelling (Kt/V), the measurement of effectiveionic dialysance (Diascan), and the continuous spent sampling of dialysate(Quantiscan).The aim of this study was to compare the reliability and agreement of thesetwo methods with the formulas proposed by the urea kinetic modelling for measuringthe dialysis dose and others haemodialysis parameters.We studied 20 stable patients (16 men/4 women) dialyzed with a monitor equippedwith the modules Diascan (DC) and Quantiscan (QC) (Integra®. Hospal). Theurea distribution volume (VD) was determined using anthropometric data (Watsonequation) and QC data. Kt/V value was calculated according to Daurgidas2nd generation formula corrected for the rebound (eKt/V), and using DC (Kt/VDC)and QC (Kt/VQC) data.The total mass of urea removed was calculated as 37,93 ± 16 g/session. TheVD calculated using Watson equation was 35.7 ± 6.6 and the VDQC was 35.06± 9.9. And they showed an significative correlation (r:0,82 p < 0.001). The (VDQCVDWatson)difference was –0.64 ± 5.8L (ns). Kt/VDC was equivalent to those ofeKt/V (1.64 ± 0.33 and 1.61 ± 0.26, mean difference –0.02 ± 0.29). However,Kt/VQC value was higher than eKt/V (1.67 ± 0.22 and 1.61 ± 0.26 mean difference0.06 ± 0.07 p < 0.01). Both values correlated highly (R2: 0.92 p < 0.001).Urea generation (G) calculated using UCM was 8.75 ± 3.4 g/24 h and those calculatedusing QC was 8.64 ± 3.21 g/24 h. Mean difference 0.10 ± 1.14 (ns). Gcalculated by UCM correlated highly with that derived from QC (R2: 0.88 p <0.001).In conclusion, Kt/VDC and Kt/VQC should be considered as valid measures fordialysis efficiency. However, the limits of agreement between Kt/VQC and eKt/Vwere closer than Kt/VDC

Medición de la dosis de diálisis mediante diferentes módulos integrados en un mismo monitor / Measure of dialysis dose by different integrated modules within the same monitoring device

La recolección total del líquido de diálisis para cuantificar la cantidad total de urea eliminada durante la hemodiálisis (HD) se ha considerado la técnica «gold estándar» para medir la dosis de diálisis. Dada la dificultad de este método se han propuesto otros alternativos como el modelo cinético de la Urea (Kt/V), la medición de la dialisancia iónica o la recogida de muestras representativas del líquido de diálisis total. El objetivo de este trabajo es comparar la fiabilidad y concordancia de dos dispositivos de medida (dialisancia iónica y recogida parcial de líquido de diálisis) integrados en el mismo monitor de diálisis y compararlos con los propuestos por el modela cinético de la urea (MCU) para la medición de la dosis de diálisis (Kt/V) y otros parámetros de HD. Para ello se estudiaron 20 pacientes (16V/4M) con una edad media de 64,5 ± 13 años, estables en programa de HD y dializados con el monitor Integra® (Hospal) equipado con los biosensores Diascan (DC) y Quantiscan (QC). El volumen de distribución de urea (VD) se calculó a partir de la fórmula de Watson y por el QC. La generación de urea se calculó a partir del MCU y el Kt/V se determinó por la fórmula de Daurgidas 2ª generación corregida para el rebote (eKt/V), por el DC y el QC. La transferencia de masa de urea medida por QC fue de 37,2 ± 13,8 g. El VD por la fórmula de Watson y por QC fue de 35,7 ± 6,6 y de 35,06 ± 9,9 L respectivamente (ns) y mostraron una correlación significativa (r: 0,82 p < 0,001). Los valores de aclaramiento (K), mediante DC, y QC fueron similares KQC: 230,3 ± 56,5 ml/min, KDC: 214,05 ± 24,3 ml/min (ns) No se apreciaron diferencias en el Kt/V calculado por DC y el eKt/V (KtVDC: 1,64 ± 0,33 vs KtVeq; 1,61 ± 0,26). El coeficiente de correlación fue de r: 0,45 (p < 0,05). Por el contrario los valores de Kt/VQC fueron superiores a los calculados por el eKtV (1,67± 0,22 vs. 1,61 ± 0,26). El coeficiente de correlación fue de r: 0,94 ( p < 0,001). La generación de urea por el MCU fue de 8,7 ± 3,4 y por QC de 8,6 ± 3,2 g/ 24h (ns) r: 0,94 p < 0,001). Podemos concluir que tanto la medición de la dialisancia iónica mediante el DC, como la recogida de muestras representativas del líquido de diálisis mediante el QC, son métodos sencillos, fiables y reproducibles que nos permiten medir de manera rápida la eficacia dialítica y otros parámetros de hemodiálisis. En nuestra experiencia la cuantificación de la dosis de diálisis mediante el QC presenta una mayor concordancia que la realizada con DC

The «gold standard» method to measure the mass balance achieved during dialysis for a given solute is based on the total dialysate collection. This procedure is unfeasible and too cumbersome. For this reason, alternative methods have been proposed including the urea kinetic modelling (Kt/V), the measurement of effective ionic dialysance (Diascan), and the continuous spent sampling of dialysate (Quantiscan). The aim of this study was to compare the reliability and agreement of these two methods with the formulas proposed by the urea kinetic modelling for measuring the dialysis dose and others haemodialysis parameters. We studied 20 stable patients (16 men/4 women) dialyzed with a monitor equipped with the modules Diascan (DC) and Quantiscan (QC) (Integra®. Hospal). The urea distribution volume (VD) was determined using anthropometric data (Watson equation) and QC data. Kt/V value was calculated according to Daurgidas 2nd generation formula corrected for the rebound (eKt/V), and using DC (Kt/VDC) and QC (Kt/VQC) data. The total mass of urea removed was calculated as 37,93 ± 16 g/session. The VD calculated using Watson equation was 35.7 ± 6.6 and the VDQC was 35.06 ± 9.9. And they showed an significative correlation (r:0,82 p < 0.001). The (VDQCVDWatson) difference was –0.64 ± 5.8L (ns). Kt/VDC was equivalent to those of eKt/V (1.64 ± 0.33 and 1.61 ± 0.26, mean difference –0.02 ± 0.29). However, Kt/VQC value was higher than eKt/V (1.67 ± 0.22 and 1.61 ± 0.26 mean difference 0.06 ± 0.07 p < 0.01). Both values correlated highly (R2: 0.92 p < 0.001). Urea generation (G) calculated using UCM was 8.75 ± 3.4 g/24 h and those calculated using QC was 8.64 ± 3.21 g/24 h. Mean difference 0.10 ± 1.14 (ns). G calculated by UCM correlated highly with that derived from QC (R2: 0.88 p < 0.001). In conclusion, Kt/VDC and Kt/VQC should be considered as valid measures for dialysis efficiency. However, the limits of agreement between Kt/VQC and eKt/V were closer than Kt/VDC

Seguimiento a largo plazo de catéteres permanentes en pacientes con dificultad en la obtención de un acceso vascular definitivo / Outcome of tunneled hemodialysis catheters as permanent vascular access

Los catéteres tunelizados para hemodiálisis se han considerado como accesos vasculares transitorios hasta conseguir otro tipo de acceso permanente. El objetivo de este estudio es la evaluación de los catéteres tunelizados permanentes (CTP), utilizados como acceso vascular definitivo en un tipo de pacientes con dificultades para lograr otro tipo de acceso vascular. Material y métodos: Se han analizado de manera retrospectiva, las características, funcionamiento, complicaciones y supervivencia de 42 CTP colocados entre noviembre de 2000 y octubre de 2003, a 40 pacientes ancianos, con enfermedades sistémicas o sin posibilidad de realizar otro acceso vascular. Resultados: El porcentaje de complicaciones en relación con la intervención fue del 11,9 por ciento (5 casos: 3 hematomas subcutáneos, 1 hemotórax y 1 rotura venosa con fallecimiento del paciente). Se retiraron 6 catéteres, 3 por mal función y 3 por infección). Los 3 casos de infección definen una relación de 0,18 episodios por 1000 catéteres-día de seguimiento. Los pacientes fueron seguidos por una media de 379 días (rango 1-1140) y un total de 15.946 pacientes-días. El Qb y KT/V conseguido al mes de su implantación fue de 278,3 ñ 34,1 y 1,48 ñ 0,27 respectivamente, sin diferencias significativas en el seguimiento. Al final del seguimiento permanecían vivos y con catéter funcionante 23 pacientes (54,7 por ciento) y 12 pacientes (28,5 por ciento) habían fallecido con catéter funcionante. La supervivencia de los catéteres fue del 90,4 por ciento a los 30 días, 73,1 por ciento a los 180 días y 59,5 por ciento a los 365 días. Conclusión: El CTP es una buena alternativa como acceso definitivo en aquellos pacientes que presentan serias dificultades para conseguir otro tipo de acceso (AU)

[Outcome of tunneled hemodialysis catheters as permanent vascular access]. / Seguimiento a largo plazo de catéteres permanentes en pacientes con dificultad en la obtención de un acceso vascular definitivo.

UNLABELLED: Tunneled cuffed hemodialysis catheters (THC) are developed as a means of short hemodialysis access while a more permanent form of access are maturing. The aim of this study is to investigate the effectiveness, survival and complications of the THC used for long-term vascular access. METHODS: In a retrospective study we looked at 42 THC inserted between November 2000 and October 2003, in 40 elderly patients, with systemic disease or when other vascular access was not possible. RESULTS: Procedural complications occurred in 5 cases (11.9%), which included: local haemorrhage (3), hemothorax (1) and one fatal venous tear. 6 catheters (14.2%) were removed due to complications (non-function 3 and bacteraemia 3). The total incidence of THC related infections was 0.18 episodes/1,000 catheters-days. Patients were followed up for a mean 379 days (range 1-1,140) and a total of 15,946 catheter-days. Qb and KT/V achieved at one month were 278.3 +/- 34.1 ml/min and 1.48 +/- 0.27 respectively. At the end of the follow-up, 23 patients (54.7%) were alive with catheter functioning. One, three and twelve months survival was 90.4%, 73.1% and 59.5% respectively. CONCLUSION: The THC may be a useful alternative permanent vascular access for hemodialysis patients when others vascular access are not possible.