Influencia de las venas colaterales en la medición del flujo del acceso vascular medicante ecografía y termodilución: estudio observacional / Influence of collateral veins on flow measurement of vascular access using ultrasound and thermodilution: an observational study

Introducción: La ecografía doppler y métodos dilucionales permiten monitorizar el flujo del acceso vascular. La presencia de venas colaterales podría influir en la determinación del flujo del acceso vascular.Objetivo: Determinar la influencia de las venas colaterales en la medición del flujo del acceso vascular por ecografía doppler y por el método de termodilución.Material y Método: Estudio observacional y prospectivo. Se seleccionaron las fístulas arteriovenosas nativas que cumplían los criterios de selección. Se realizó una medición anual del flujo del acceso vascular mediante ecografía-doppler y 2 mediciones trimestrales de termodilución (termodilución-1 y termodilución-2). Para determinar la presencia de venas colaterales se empleó el ecógrafo.Resultados: Se analizaron 38 fístulas arteriovenosas nativas. Los hombres representaban el 78,9% de la muestra. El 23,6% presentaban venas colaterales. Analizando la totalidad de la muestra, se obtuvo correlación lineal entre los flujos por ecografía-doppler con los de termodilución-1 (0,694) y con termodilución-2 (0,678), ambas p<0,001. Al estratificar por venas colaterales, se observó correlación significativa entre ecografía-doppler con termodilución-1 (0,698) y termodilución-2 (0,696) ambas significativas (p<0,001) cuando no existían venas colaterales, correlación no significativa cuando si había venas colaterales.Conclusiones: Existe correlación entre la medición del flujo del acceso vascular obtenido por ecografía-doppler y termodilución; la presencia de venas colaterales modifica esta relación. Es necesario implementar programas de vigilancia del acceso vascular que incluyan diferentes métodos de monitorización, para mitigar el efecto que las venas colaterales tienen en la determinación del flujo del acceso vascular. (AU)

Introduction: Doppler ultrasound and dilutional methods allow monitoring of vascular access flow. The presence of collateral veins may influence the determination of vascular access flow.Objective: To determine the influence of collateral veins on the vascular access flow measurement by Doppler ultrasound and by the thermodilution method.Material and Method: Observational and prospective study. Native arteriovenous fistulas that met the selection criteria were selected. An annual measurement of vascular access flow by Doppler ultrasound and two quarterly thermodilu-tion measurements (thermodilution-1 and thermodilution-2) were performed. Ultrasound was used to determine the pre-sence of collateral veins.Results: Thirty-eight native arteriovenous fistulae were analysed. Males accounted for 78.9% of the sample. Collateral veins were present in 23.6% of cases. Analysing the whole sample, a linear correlation was obtained between ultrasound-Doppler flows with thermodilution-1 (0.694) and thermodilution-2 (0.678), [both p<0.001]. When stratified by collateral veins, when no collateral veins were present, there was a significant correlation between Doppler ultrasound with thermodilution-1 (0.698) and thermodilution-2 (0.696) [both p<0.001)]; whereas the correlation was non-significant when collateral veins were present.Conclusions: There is correlation between vascular access flow measurement obtained by Doppler ultrasound and thermodilution; the presence of collateral veins modifies such relationship. It is necessary to implement vascular access surveillance programs that include different monitoring methods in order to mitigate the effect of collateral veins on vascular access flow determination. (AU)

Validation of the inverse method for the determination of the access flow with thermodilution.

INTRODUCTION: Thermodiluction is a widely used method for measuring vascular access flow (QA). Among the possibilities of TD, the reverse method (MI) can be beneficial in the execution time, without impact on the dialysis efficacy (Kt). However, it is not a sufficiently studied technique. METHOD: Transversal study of 117 arteriovenous fistulas (AVF). Two QA measurements were taken with the method described by the manufacturer (MR) and another with MI. MI is bases in the obtention of an inverted recirculation registry at the beginning of the session and a single subsequent recirculation measurement with the lines in normal position. In the concordance analysis, the Bland-Altman method and Cohen's Kappa index were used. RESULTS: Very good concordance between MR and MI was evidenced for QA below 700 ml/min, but it worsens as flow increases. The median variability between the MR measurements (intra-method variability) was 3.4% (-17.13). This value did not differ from the median variability generated between MR and MI (inter-method variability), which was 2% (-14, 12) (P = 0.287). The degree of agreement between the two to identify AVFs susceptible to intervention was very good (K = 0.834). The time spent using the MI was significantly shorter (P = 0.000) without evidence of variations in the Kt of the measurement sessions (P = 0.201). CONCLUSIONS: The thermodiluction MI is valid to determine the flow of the vascular access, especially in Qa lower than 700 ml/min, with great time savings, simplification of the procedure and without modifying the dialysis efficiency. The variability between the measurement by MR and MI is similar to that of MR. The concordance between methods in identifying potentially pathological AVFs is very good.

Validación del método inverso para la determinación del flujo de acceso con termodilución / Validation of the inverse method for the determination of the access flow with thermodilution

Introducción: La termodilución es un método ampliamente usado para la medición del flujo de acceso vascular (QA). Entre las posibilidades de la termodilución, el método inverso (MI) puede ser beneficioso en el tiempo de ejecución, sin repercusión en la eficacia dialítica (Kt). Sin embargo, no es una técnica lo suficientemente estudiada.MétodoEstudio transversal sobre 117 fístulas arteriovenosas. Se realizaron 2 mediciones de QA con el método descrito por el fabricante (MR) y otra con MI. El MI se basa en la obtención del registro de recirculación invertida al iniciar la sesión y una única medición posterior de recirculación con las líneas en posición normal. En el análisis de concordancia se utilizó el método Bland-Altman y el índice kappa de Cohen.ResultadosSe evidenció muy buena concordancia entre MR y MI para QA inferiores a 700ml/min, pero empeora a medida que aumenta el flujo. La variabilidad mediana entre las mediciones con MR (variabilidad intramétodo) fue del 3,4% (−17,13). Este valor no difirió de la variabilidad mediana generada entre MR y MI (variabilidad intermétodo), que fue del 2% (−14,12) (p=0,287). El grado de acuerdo entre ambos para identificar fístulas arteriovenosas susceptibles de intervención fue muy bueno (kappa=0,834). El tiempo empleado utilizando el MI fue significativamente menor (p=0,000), sin evidenciarse variaciones en el Kt de las sesiones de medida (p=0,201).ConclusionesEl MI de termodilución es válido para determinar el flujo del acceso vascular, especialmente en QA inferiores a 700ml/min, con gran ahorro de tiempo, simplificación del procedimiento y sin modificar la eficacia de diálisis. La variabilidad entre la medición por MR y MI es similar a la propia del MR. La concordancia entre métodos a la hora de identificar fístulas arteriovenosas potencialmente patológicas es muy buena. (AU)

Introduction: Thermodilution is a widely used method for measuring vascular access flow (QA). Among the possibilities of thermodilution, the reverse method (RM) can be beneficial in the execution time, without impact on the dialysis efficacy (Kt). However, it is not a sufficiently studied technique.MethodTransversal study of 117 arteriovenous fistulas. Two QA measurements were taken with the method described by the manufacturer (MR) and another with RM. RM is based on the obtention of an inverted recirculation registry at the beginning of the session and a single subsequent recirculation measurement with the lines in normal position. In the concordance analysis, the Bland-Altman method and Cohen's Kappa index were used.ResultsVery good concordance between MR and RM was evidenced for QA below 700ml/min, but it worsens as flow increases. The median variability between the MR measurements (intra-method variability) was 3.4% (−17.13). This value did not differ from the median variability generated between MR and RM (inter-method variability), which was 2% (−14,12) (P=.287). The degree of agreement between the 2 to identify arteriovenous fistulas susceptible to intervention was very good (Kappa=0.834). The time spent using the RM was significantly shorter (P=.000) without evidence of variations in the Kt of the measurement sessions (P=.201).ConclusionsThe thermodilution RM is valid to determine the flow of the vascular access, especially in QA lower than 700ml/min, with great time savings, simplification of the procedure and without modifying the dialysis efficiency. The variability between the measurement by MR and RM is similar to that of MR. The concordance between methods in identifying potentially pathological arteriovenous fistulas is very good. (AU)

Correlación del gasto cardiaco por fórmula de continuidad a través de ecocardiografía transtorácica vs termodilución por Swan-Ganz en la Unidad de Cuidados Intensivos / Correlation of cardiac output by continuity formula through transthoracic echocardiography vs thermodilution by Swan-Ganz in the Intensive Care Unit / Correlação do débito cardíaco pela fórmula de continuidade através da ecocardiografia transtorácica vs termodiluição por Swan-Ganz na unidade de terapia intensiva

Resumen: Introducción: la termodilución se considera el estándar de referencia para la medición del gasto cardiaco. Durante las últimas décadas la aparición de otros métodos menos invasivos ha resultado útil para determinar el gasto cardiaco. El objetivo del estudio es analizar la correlación entre el gasto cardiaco obtenido por ecocardiografía transtorácica mediante el método de continuidad y termodilución pulmonar por catéter de Swan-Ganz. Material y métodos: estudio prospectivo, descriptivo, transversal realizado en la Unidad de Cuidados Intensivos del Hospital General Las Américas. A los pacientes se les colocó catéter Swan-Ganz; se realizó medición de gasto cardiaco por ecocardiografía; posteriormente cuantificación de gasto cardiaco por termodilución pulmonar durante marzo de 2021 a agosto de 2022. Resultados: se compararon 58 mediciones de gasto cardiaco (GC) por Swan-Ganz con una mediana de 4.95 (rango 3.1-7.2), y GC por ecocardiografía con una mediana 4.93 (rango 3.2-7.0). La diferencia de medias para la medición de gasto cardiaco por Swan-Ganz fue de 5.20 (95% IC 4.56-5.84, p < 0.0001), comparado con gasto cardiaco por termodilución 5.19 (95% IC 4.56-5.81, p < 0.0001). Conclusiones: existe correlación significativa entre el gasto cardiaco medido por termodilución y ecocardiografía; se le considera una alternativa confiable para la determinación del gasto cardiaco.

Abstract: Introduction: thermodilution considered the reference standard for measuring cardiac output. During the last decades, the appearance of other less invasive methods has been useful to determine cardiac output. The aim of the study is to analyze the correlation between cardiac output obtained by transthoracic echocardiography by continuity method and pulmonary thermodilution by Swan-Ganz catheter. Material and methods: prospective, descriptive, cross-sectional study carried out in the Intensive Care Unit of the Hospital General Las Américas, the patients underwent a Swan-Ganz catheter; cardiac output was measured by echocardiography; subsequently, quantification of cardiac output by pulmonary thermodilution during March 2021 to August 2022. Results: fifty-eight measurements of cardiac output by Swan-Ganz with a median of 4.95 (range 3.1-7.2) and CO by echocardiography with a median of 4.93 (range 3.2-7.0) were compared. The difference in means for the measurement of cardiac output by Swan-Ganz was 5.20 (95% CI 4.56-5.84 p < 0.0001), compared to cardiac output by thermodilution 5.19 (95% CI 4.56-5.81 p < 0.0001). Conclusions: there is a significant correlation between cardiac output measured by thermodilution and echocardiography; being considered a reliable alternative for the determination of cardiac output.

Resumo: Introdução: a termodiluição é considerada o padrão de referência para a medida do débito cardíaco. Nas últimas décadas, o surgimento de outros métodos menos invasivos mostrou-se útil para a determinação do débito cardíaco. O objetivo do estudo é analisar a correlação entre o débito cardíaco obtido pela ecocardiografia transtorácica pelo método da continuidade e a termodiluição pulmonar pelo cateter de Swan-Ganz. Material e métodos: estudo prospectivo, descritivo, transversal, realizado na Unidade de Terapia Intensiva do Hospital Geral Las Américas, onde foi colocado cateter de Swan-Ganz; o débito cardíaco foi medido por ecocardiografia; posteriormente, quantificação do débito cardíaco por termodiluição pulmonar no período de março de 2021 a agosto de 2022. Resultados: foram comparadas 58 medidas do débito cardíaco por Swan-Ganz com uma mediana de 4.95 (intervalo 3.1-7.2), e GC por ecocardiografia com uma mediana de 4.93 (intervalo 3.2-7.0). A diferença média para medição do débito cardíaco por Swan-Ganz foi de 5.20 (IC 95% 4.56-5.84 p < 0.0001), em comparação com o débito cardíaco por termodiluição 5.19 (95% CI 4.56-5.81 p < 0.0001). Conclusões: existe uma correlação significativa entre o débito cardíaco medido por termodiluição e ecocardiografia; considerando-o uma alternativa confiável para a determinação do débito cardíaco.

Validation of the inverse method for the determination of the access flow with thermodilution. / Validación del método inverso para la determinación del flujo de acceso con termodilución.

INTRODUCTION: Thermodilution is a widely used method for measuring vascular access flow (QA). Among the possibilities of thermodilution, the reverse method (RM) can be beneficial in the execution time, without impact on the dialysis efficacy (Kt). However, it is not a sufficiently studied technique. METHOD: Transversal study of 117 arteriovenous fistulas. Two QA measurements were taken with the method described by the manufacturer (MR) and another with RM. RM is based on the obtention of an inverted recirculation registry at the beginning of the session and a single subsequent recirculation measurement with the lines in normal position. In the concordance analysis, the Bland-Altman method and Cohen's Kappa index were used. RESULTS: Very good concordance between MR and RM was evidenced for QA below 700ml/min, but it worsens as flow increases. The median variability between the MR measurements (intra-method variability) was 3.4% (-17.13). This value did not differ from the median variability generated between MR and RM (inter-method variability), which was 2% (-14,12) (P=.287). The degree of agreement between the 2 to identify arteriovenous fistulas susceptible to intervention was very good (Kappa=0.834). The time spent using the RM was significantly shorter (P=.000) without evidence of variations in the Kt of the measurement sessions (P=.201). CONCLUSIONS: The thermodilution RM is valid to determine the flow of the vascular access, especially in QA lower than 700ml/min, with great time savings, simplification of the procedure and without modifying the dialysis efficiency. The variability between the measurement by MR and RM is similar to that of MR. The concordance between methods in identifying potentially pathological arteriovenous fistulas is very good.

Asociación entre el índice de agua extravascular pulmonar y el balance hídrico en pacientes críticamente enfermos / Association between extravascular lung water index and fluid balance in critically ill patients / Associação entre água extravascular pulmonar indexada e balanço hídrico em pacientes em estado crítico

Resumen: Introducción: El balance hídrico positivo y el agua extravascular pulmonar medida por termodilución transpulmonar son factores independientes de mortalidad. La inclusión del valor de agua extravascular pulmonar indexada (EVLWi) durante la reanimación inicial impacta en la cantidad de líquido administrado. Aunque no existen antecedentes, buscar una asociación entre ambos parámetros puede llevar a un balance hídrico global negativo guiado por la cantidad de EVLWi. En este estudio retrospectivo se buscó la asociación entre EVLWi y balance hídrico y su impacto en la mortalidad. Material y métodos: Se realizó un estudio retrospectivo de cohortes con 20 casos para establecer la asociación entre agua extravascular pulmonar indexada medida por termodilución transpulmonar y balance hídrico total a las 24, 48 y 72 horas, así como con la mortalidad a 30 días. Resultados: Un valor de corte > 11 mL/kg de EVLWi se asoció con un incremento de la mortalidad; a las 24 horas RR 8.0 (95% IC 1.2146-52.6944, p = 0.0306), a las 48 horas RR 4.3778 (95% IC 1.1643-15.7177, p = 0.0286) y a las 72 horas con RR 3.5000 (95% IC 0.9497-12.8983, p = 0.0598). El valor de corte del balance hídrico fue ≥ 3.5 L, sin asociación con la mortalidad RR 0.1789 (95% IC 0.0125-2.5668, p = 0.2054) a las 24 horas, RR 0.5000 (95% IC 0.0854-2.9258, p = 0.4419) a las 48 horas y RR 0.3750 (95% IC 0.0610-2.3059, p = 0.2897) a las 72 horas. La asociación entre balance hídrico total y EVLWi fue r (2) Pearson = 0.01269. Conclusiones: El EVLWi > 11 mL/kg se asoció a un incremento en la mortalidad, a diferencia del balance hídrico. No encontramos correlación entre el balance hídrico y el EVLWi.

Abstract: Introduction: Positive fluid balance and extravascular lung water index (EVLWi) quantified by transpulmonary thermodilution have been important independent mortality prognostic factors. Including EVLWi to guide initial fluid reanimation therapy has a high impact in the amount of administered fluid. Although there is not enough evidence, search for an association between EVLWi and fluid balance could lead to a negative fluid balance driven by EVLWi to improve survival rates. In this retrospective study we search for the association between EVLWi, fluid balance and its impact on mortality. Material and methods: Retrospective, cohort study of 20 cases. We looked for any association between EVLWi by transpulmonary thermodilution and daily fluid balance at 24, 48 and 72 hours and reviewed mortality at 30 days. Results: An EVLWi cutoff value of > 11 mL/kg was associated with a higher mortality; on the first 24 hours with an RR 8.0 (95% CI 1.2146-52.6944, p = 0.0306), at 48 hours RR 4.3778 (95% CI 1.1643-15.7177, p = 0.0286) and at 72 hours RR 3.5000 (95% CI 0.9497-12.8983 p = 0.0598). Fluid balance cutoff value was established at ≥ 3.5 L, but we can't find any association with mortality, RR 0.1789 (95% CI 0.0125-2.5668, p = 0.2054) at 24 hours, RR 0.5000 (95% CI 0.0854-2.9258, p = 0.4419) at 48 hours y RR 0.3750 (95% CI 0.0610-2.3059, p = 0.2897) at 72 hours. The correlation between fluid balance and EVLWi was negative, Pearson's r (2) = 0.01269. Conclusions: EVLWi was associated to a higher mortality. We could not demonstrate an association between fluid balance and EVLWi.

Resumo: Introdução: O balanço hídrico positivo e a água extravascular pulmonar medida por termodiluição transpulmonar são fatores independentes da mortalidade. A inclusão do valor de água extravascular pulmonar indexada (EVLWi) durante a ressuscitação inicial impacta a quantidade de fluido entregue. Embora não haja precedente, buscar uma associação entre os dois parâmetros pode levar a um balanço hídrico global negativo guiado pela quantidade de EVLWi. Neste estudo retrospectivo, buscou-se a associação entre EVLWi e balanço hídrico e seu impacto na mortalidade. Material e métodos: Foi realizado um estudo de coorte retrospectivo com 20 casos para estabelecer a associação entre a água pulmonar extravascular indexada medida por termodiluição transpulmonar e balanço hídrico total em 24, 48 e 72 horas, bem como mortalidade em 30 dias. Resultados: Um valor de corte > 11 mL/kg de EVLWi foi associado a um aumento na mortalidade; às 24 horas RR 8.0 (95% IC 1.2146-52.6944, p = 0.0306), 48 horas RR 4.3778 (95% IC 1.1643-15.7177, p = 0.0286) e 72 horas com RR 3.5000 (95% IC 0.9497-12.8983 p = 0.0598). O valor de corte do balanço hídrico foi ≥ 3.5 L, sem associação com mortalidade RR 0.1789 (IC 95% 0.0125-2.5668, p = 0.2054) em 24 horas, RR 0.5000 (IC 95% 0.0854-2.9258 p = 0.4419) em 48 horas e RR 0.3750 (IC 95% 0.0610-2.3059 p = 0.2897) às 72 horas. A associação entre balanço hídrico total e EVLWi foi r 2 Pearson = 0.01269. Conclusões: EVLWi > 11 mL/kg foi associado a um aumento da mortalidade, em contraste com o balanço hídrico. Não encontramos correlação entre o balanço hídrico e o EVLWi.

Correlación de gasto cardiaco obtenido por termodilución y por monitor ultrasónico (USCOM) en pacientes con choque séptico / Correlation of cardiac output obtained by termodulution and by ultrasonic monitor in patients with septic shock (USCOM) / Correlação do débito cardíaco obtido pela termodulação e pelo monitor ultrasônico (USCOM) em pacientes com choque septico

Resumen: El catéter en la arteria pulmonar (CAP) es un dispositivo utilizado en unidades de cuidados intensivos (UCI) para medir las presiones en el corazón y los vasos sanguíneos pulmonares como parte del monitoreo hemodinámico, principalmente en pacientes de cirugía cardiaca. El dispositivo USCOM se trata de una técnica no invasiva que utiliza la tecnología Doppler para obtener las medidas de volumen sistólico y sus derivados. Se realiza la siguiente comparación de medición de GC entre estos dos dispositivos en pacientes con choque séptico. Se realizó un estudio tipo observacional, prospectivo, longitudinal y comparativo en pacientes con choque séptico entre 18 y 60 años de edad ingresados en la UTI en el periodo de mayo-junio del 2017. Ante la disminución del uso del catéter de la arteria pulmonar debido a la controversia de no mejorar la mortalidad en los pacientes de las unidades de terapia intensiva (UTI), la colocación de dicho catéter ha caído en desuso; sin embargo, el GC medido por el catéter de Swan-Ganz sigue siendo el «estándar de oro¼ para la medición en tiempo real del GC y las resistencias sistémicas y pulmonares. La medición del GC por CAP versus USCOM se correlaciona de tal forma que puede emplearse en la medición por USCOM en un paciente con choque séptico, al cual no se le pretenda invadir para determinar sus condiciones hemodinámicas.

Abstract: The pulmonary artery catheter (CAP) is a device used in intensive care units (ICUs) to measure pressures in the heart and pulmonary blood vessels as part of hemodynamic monitoring primarily in cardiac surgery patients. The USCOM device is a non-invasive technique that uses Doppler technology to obtain measurements of systolic volume and its derivatives. The following CO measurement comparison is performed between these two devices in patients with septic shock. An observational, prospective, longitudinal and comparative study was conducted in patients with septic shock aged between 18 and 60 years admitted to intensive care in the period May-June 2017. In view of the decrease in the use of the pulmonary artery catheter due to the controversy of not improving the mortality in the patients of the Intensive Care Units, the placement of this catheter has fallen into disuse; however, cardiac output measured by the Swan Ganz catheter remains the «gold standard¼ for real-time measurement of cardiac output and systemic and pulmonary resistance. The CO measurement by PAC versus USCOM correlates, in such a way, that USCOM measurement can be used in a patient with septic shock, who is not expected to invade to determine their hemodynamic conditions.

Resumo: O cateter de artéria pulmonar (CAP) é um dispositivo utilizado em unidades de terapia intensiva (UTI) para medir as pressões nos vasos sanguíneos cardíacos e pulmonares, como parte da monitorização hemodinâmica, principalmente em pacientes submetidos a cirurgia cardíaca. O dispositivo USCOM é uma técnica não invasiva que utiliza a tecnologia Doppler para obter medidas do volume sistólico e seus derivados. A seguinte comparação da medição do DC é feita entre esses dois dispositivos em pacientes com choque séptico. Foi realizado um estudo observacional, prospectivo, longitudinal e comparativo em pacientes com choque séptico com idade entre 18 e 60 anos internados na unidade de terapia intensiva no período de maio a junho de 2017. Dada a diminuição do uso do cateter de artéria pulmonar devido à controvérsia de não melhorar a mortalidade nos pacientes das Unidades de Terapia Intensiva, a colocação do referido cateter caiu em desuso; no entanto, o débito cardíaco medido pelo cateter de Swan Ganz continua sendo o «padrão ouro¼ para a medição em tempo real do débito cardíaco e resistências sistêmicas e pulmonares. A medida do DC por CAP vs USCOM está correlacionada, de tal forma que a medida por USCOM pode ser usada em um paciente com choque séptico, que não se destina a invadir para determinar suas condições hemodinâmicas.

Evaluation of concordance among three cardiac output measurement techniques in adult patients during cardiovascular surgery postoperative care.

INTRODUCTION: The standard method for cardiac output measuring is thermodilution although it is an invasive technique. Transesophageal Echocardiography (TEE) offers a dynamic and functional alternative to thermodilution. OBJECTIVE: Analyze concordance between two TEE methods and thermodilution for cardiac output assessment. METHODS: Observational concordance study in cardiovascular surgery patients that required pulmonary artery catheter. TEE cardiac output measurement at both mitral annulus (MA) and left ventricle outflow tract (LVOT) were performed. Results were compared with thermodilution. Correlation was evaluated by Lin's concordance correlation coefficient and Bland-Altman analysis. Statistical analysis was undertaken in STATA 13.0. RESULTS: Twenty-five patients were enrolled. Fifty two percent of patients were male, median age and ejection fraction was 63 years and 35% respectively. Median thermodilution, LVOT and MA -measured cardiac output was 3.25 L/min, 3.46 L/min and 8.4 L/min respectively. Different values between thermodilution and MA measurements were found (Lin concordance=0.071; Confidence Interval 95%=-0.009 to 0.151; Spearman's correlation=0.22) as values between thermodilution and LVOT (Lin concordance=0.232; Confidence Interval 95%=-0.12 a 0.537; Spearman's correlation 0.28). Bland-Altman analysis showed greater difference between MA measurements and thermodilution (DM=-0.408; Bland-Altman Limits=-0.809 to -0.007), than the other echocardiographic findings (DM=0.007; Bland-Altman Limits=-0.441 to 0.428). CONCLUSION: Results from cardiac output measurement by doppler and 2D-TEE on both MA and LVOT do not correlate with those obtained by thermodilution.

Invasive radiologic management of hemodialysis fistulas: measuring flow with an endovascular catheter.

OBJECTIVES: To analyze the values of flow obtained with an endovascular catheter, and to determine whether they are more reliable than angiographic and clinical findings for planning and for determining the outcome of invasive radiologic treatment of hemodialysis fistulas, as well as to determine the safety of this technique during interventional radiology procedures. MATERIAL AND METHODS: We used endovascular catheters to measure flow in 341 vascular accesses for hemodialysis (162 [47.6%] distal fistulas, 132 [38.4%] humeral fistulas, and 47 [14%] arteriovenous grafts) in 598 procedures (a total of 3,051 flow measurements). Dysfunction was most commonly due to high pressures and flow deficits. RESULTS: The catheter was used to measure the results of radiologic treatment in 419 (70%) cases and only to measure the control of flow in the hemodialysis access in 179 (30%) cases. In the cases where lesions of the access had been treated radiologically, the flow improved by a mean of 1,232ml/min. In 2 (0.35%) cases, the tip of the catheter perforated the wall of the vein; this complication was resolved by inflating a low pressure balloon. CONCLUSIONS: Endovascular catheters are useful for measuring flow in invasive vascular radiology procedures for hemodialysis. In assessing the hemodynamic status of a vascular access, they are most helpful in determining whether stenosis is present.