Venoarterial PCO₂-to-arteriovenous oxygen content difference ratio is a poor surrogate for anaerobic metabolism in hemodilution: an experimental study

Background: The identification of anaerobic metabolism in critically ill patients is a challenging task. Observational studies have suggested that the ratio of venoarterial PCO2 (Pv–aCO2) to arteriovenous oxygen content difference (Ca–vO2) might be a good surrogate for respiratory quotient (RQ). Yet Pv–aCO2/Ca–vO2 might be increased by other factors, regardless of anaerobic metabolism. At present, comparisons between Pv–aCO2/Ca–vO2 and RQ have not been performed. We sought to compare these variables during stepwise hemorrhage and hemodilution. Since anemia predictably produces augmented Pv–aCO2 and decreased Ca–vO2, our hypothesis was that Pv–aCO2/Ca–vO2 might be an inadequate surrogate for RQ. Methods: This is a subanalysis of a previously published study. In anesthetized and mechanically ventilated sheep (n = 16), we compared the effects of progressive hemodilution and hemorrhage by means of expired gases analysis. Results: There were comparable reductions in oxygen consumption and increases in RQ in the last step of hemodilution and hemorrhage. The increase in Pv–aCO2/Ca–vO2 was higher in hemodilution than in hemorrhage (1.9 ± 0.2 to 10.0 ± 0.9 vs. 1.7 ± 0.2 to 2.5 ± 0.1, P < 0.0001). The increase in Pv–aCO2 was lower in hemodilution (6 ± 0 to 10 ± 1 vs. 6 ± 0 to 17 ± 1 mmHg, P < 0.0001). Venoarterial CO2 content difference and Ca–vO2 decreased in hemodilution and increased in hemorrhage (2.6 ± 0.3 to 1.2 ± 0.1 vs. 2.8 ± 0.2 to 6.9 ± 0.5, and 3.4 ± 0.3 to 1.0 ± 0.3 vs. 3.6 ± 0.3 to 6.8 ± 0.3 mL/dL, P < 0.0001 for both). In hemodilution, Pv–aCO2/Ca–vO2 increased before the fall in oxygen consumption and the increase in RQ. Pv–aCO2/Ca–vO2 was strongly correlated with Hb (R2 = 0.79, P < 0.00001) and moderately with RQ (R2 = 0.41, P < 0.0001). A multiple linear regression model found Hb, RQ, base excess, and mixed venous oxygen saturation and PCO2 as Pv–aCO2/Ca–vO2 determinants (adjusted R2 = 0.86, P < 0.000001). Conclusions: In hemodilution, Pv–aCO2/Ca–vO2 was considerably increased, irrespective of the presence of anaerobic metabolism. Pv–aCO2/Ca–vO2 is a complex variable, which depends on several factors. As such, it was a misleading indicator of anaerobic metabolism in hemodilution.Facultad de Ciencias Médica

Venoarterial PCO₂-to-arteriovenous oxygen content difference ratio is a poor surrogate for anaerobic metabolism in hemodilution: an experimental study

Background: The identification of anaerobic metabolism in critically ill patients is a challenging task. Observational studies have suggested that the ratio of venoarterial PCO2 (Pv–aCO2) to arteriovenous oxygen content difference (Ca–vO2) might be a good surrogate for respiratory quotient (RQ). Yet Pv–aCO2/Ca–vO2 might be increased by other factors, regardless of anaerobic metabolism. At present, comparisons between Pv–aCO2/Ca–vO2 and RQ have not been performed. We sought to compare these variables during stepwise hemorrhage and hemodilution. Since anemia predictably produces augmented Pv–aCO2 and decreased Ca–vO2, our hypothesis was that Pv–aCO2/Ca–vO2 might be an inadequate surrogate for RQ. Methods: This is a subanalysis of a previously published study. In anesthetized and mechanically ventilated sheep (n = 16), we compared the effects of progressive hemodilution and hemorrhage by means of expired gases analysis. Results: There were comparable reductions in oxygen consumption and increases in RQ in the last step of hemodilution and hemorrhage. The increase in Pv–aCO2/Ca–vO2 was higher in hemodilution than in hemorrhage (1.9 ± 0.2 to 10.0 ± 0.9 vs. 1.7 ± 0.2 to 2.5 ± 0.1, P < 0.0001). The increase in Pv–aCO2 was lower in hemodilution (6 ± 0 to 10 ± 1 vs. 6 ± 0 to 17 ± 1 mmHg, P < 0.0001). Venoarterial CO2 content difference and Ca–vO2 decreased in hemodilution and increased in hemorrhage (2.6 ± 0.3 to 1.2 ± 0.1 vs. 2.8 ± 0.2 to 6.9 ± 0.5, and 3.4 ± 0.3 to 1.0 ± 0.3 vs. 3.6 ± 0.3 to 6.8 ± 0.3 mL/dL, P < 0.0001 for both). In hemodilution, Pv–aCO2/Ca–vO2 increased before the fall in oxygen consumption and the increase in RQ. Pv–aCO2/Ca–vO2 was strongly correlated with Hb (R2 = 0.79, P < 0.00001) and moderately with RQ (R2 = 0.41, P < 0.0001). A multiple linear regression model found Hb, RQ, base excess, and mixed venous oxygen saturation and PCO2 as Pv–aCO2/Ca–vO2 determinants (adjusted R2 = 0.86, P < 0.000001). Conclusions: In hemodilution, Pv–aCO2/Ca–vO2 was considerably increased, irrespective of the presence of anaerobic metabolism. Pv–aCO2/Ca–vO2 is a complex variable, which depends on several factors. As such, it was a misleading indicator of anaerobic metabolism in hemodilution.Facultad de Ciencias Médica

0588. Effects of norepinephrine on tissue perfusion in a sheep model of intraabdominal hypertension

Intraabdominal hypertension (IAH) produces detrimental effects on tissue perfusion. A putative underlying mechanism is the decrease in abdominal perfusion pressure (APP = mean arterial pressure-intraabdominal pressure). Nevertheless, the benefits of increasing blood pressure on tissue perfusion are controversial.Facultad de Ciencias Médica

Caracterización química y espectroscópica de material particulado en aire extramuros en la ciudad de La Plata y alrededores

Este trabajo se centra en la caracterización química y espectroscópica de material particulado (MP10 y MP2.5) en la ciudad de La Plata y alrededores, que cuenta con alto tránsito vehicular y un polo petroquímico cercano, diferenciando tres zonas: residencial, urbano e industrial. Se analizó su contenido en metales pesados (Cd, Cr, Cu, Mn, Ni y Pb) y se realizó un análisis morfológico del MP mediante microscopía electrónica de barrido (SEM-EDS). Los niveles de MP evidencian mayores valores tanto para MP2.5 como para MP10 en la zona industrial, seguida por la zona urbana y por último por la zona residencial. Respecto a los metales se confirma la presencia de los metales Cr, Cu, Mn y Pb en ambas fracciones de MP y para las distintas zonas de estudio, con valores de concentración desde 0.0003 μg/m3 hasta 0.0491 μg/m3. Mediante la técnica SEM-EDS los resultados obtenidos muestran partículas mayoritariamente ricas en elementos como Si, C y O, y en menor medida en Al, Ca, Na, N y con presencia de partículas de morfología relacionadas al tráfico vehicular.Facultad de Ciencias Exacta

Caracterización química y espectroscópica de material particulado en aire extramuros en la ciudad de La Plata y alrededores

Este trabajo se centra en la caracterización química y espectroscópica de material particulado (MP10 y MP2.5) en la ciudad de La Plata y alrededores, que cuenta con alto tránsito vehicular y un polo petroquímico cercano, diferenciando tres zonas: residencial, urbano e industrial. Se analizó su contenido en metales pesados (Cd, Cr, Cu, Mn, Ni y Pb) y se realizó un análisis morfológico del MP mediante microscopía electrónica de barrido (SEM-EDS). Los niveles de MP evidencian mayores valores tanto para MP2.5 como para MP10 en la zona industrial, seguida por la zona urbana y por último por la zona residencial. Respecto a los metales se confirma la presencia de los metales Cr, Cu, Mn y Pb en ambas fracciones de MP y para las distintas zonas de estudio, con valores de concentración desde 0.0003 μg/m3 hasta 0.0491 μg/m3. Mediante la técnica SEM-EDS los resultados obtenidos muestran partículas mayoritariamente ricas en elementos como Si, C y O, y en menor medida en Al, Ca, Na, N y con presencia de partículas de morfología relacionadas al tráfico vehicular.Facultad de Ciencias Exacta

Caracterización química y espectroscópica de material particulado en aire extramuros en la ciudad de La Plata y alrededores

Este trabajo se centra en la caracterización química y espectroscópica de material particulado (MP10 y MP2.5) en la ciudad de La Plata y alrededores, que cuenta con alto tránsito vehicular y un polo petroquímico cercano, diferenciando tres zonas: residencial, urbano e industrial. Se analizó su contenido en metales pesados (Cd, Cr, Cu, Mn, Ni y Pb) y se realizó un análisis morfológico del MP mediante microscopía electrónica de barrido (SEM-EDS). Los niveles de MP evidencian mayores valores tanto para MP2.5 como para MP10 en la zona industrial, seguida por la zona urbana y por último por la zona residencial. Respecto a los metales se confirma la presencia de los metales Cr, Cu, Mn y Pb en ambas fracciones de MP y para las distintas zonas de estudio, con valores de concentración desde 0.0003 μg/m3 hasta 0.0491 μg/m3. Mediante la técnica SEM-EDS los resultados obtenidos muestran partículas mayoritariamente ricas en elementos como Si, C y O, y en menor medida en Al, Ca, Na, N y con presencia de partículas de morfología relacionadas al tráfico vehicular.Facultad de Ciencias Exacta

Contribution of diet to lead exposure among children aged 1 to 7 years in La Plata, Buenos Aires

Introducción. El plomo es un metal tóxico, que, aun en bajas concentraciones sanguíneas, es capaz de alterar el normal desarrollo neurológico de los niños, por lo que no existe un nivel aceptable de plombemia. La absorción de plomo de los alimentos es la mayor contribución a los niveles de plombemia de la población no expuesta laboralmente o a ambientes contaminados. El objetivo fue determinar la contribución dietaria a la exposición al plomo en niños de 1 a 7 años de edad que concurrían por controles de salud al Hospital de Niños de La Plata. Población y métodos. El estudio se realizó entre junio de 2015 y mayo de 2016. Se realizó un cuestionario de frecuencia de consumo de alimentos sobre 91 niños cuya edad promedio ± desvío estándar fue de 3,0 ± 1,7 años, sobre la cual se seleccionaron los alimentos por analizar. Se compraron los alimentos seleccionados en diversos comercios de la región. Se armaron muestras compuestas de diversos grupos de alimentos. Se determinó la concentración de plomo en los grupos de alimentos y, finalmente, se estimó la ingesta diaria de plomo de la población estudiada. Resultados. La ingesta diaria de plomo fue de 138 µg/día.Los grupos de alimentos que tuvieron mayor contribución fueron los productos cárnicos procesados (15,4%), los panificados (14,8%), la leche (12,5%) y la carne (11,7%). Conclusiones. Los niños de 1 a 7 años que concurren a un hospital público de La Plata tienen una carga de plomo en la dieta de 138 µg/día.Introduction. Lead is a toxic metal which, even at low blood levels, can alter normal neurodevelopment in children, so no blood lead level is acceptable. Lead absorption from diet accounts for the highest contribution to blood lead levels in the population who is not exposed to contaminated environments or because of their occupation. The objective of this study was to determine the contribution of diet to lead exposure among children aged 1 to 7 years who attended Hospital de Niños de La Plata for health check-ups. Population and methods. The study was conducted between June 2015 and May 2016. A questionnaire on the frequency of food intake was administered to 91 children whose average age ± standard deviation was 3.0 ± 1.7 years, and foods included in the analysis were selectedbased on this questionnaire. Selected foods were purchased from different regional stores. Composite samples were made up of different food groups. Lead levels corresponding to each food group were determined and, finally, the daily intake of lead was estimated for the studied population. Results. The daily intake of lead was 138 µg/day. The food groups with the higher intake rates were processed meat products (15.4%), bakery products (14.8%), milk (12.5%), and meat (11.7%). Conclusions. Children aged 1 to 7 years attending a public hospital in La Plata have a lead burden from dietary intake of 138 µg/day.Facultad de Ciencias ExactasCentro de Investigación y Desarrollo en Ciencias AplicadasCentro de Investigaciones del Medioambient

Contribution of diet to lead exposure among children aged 1 to 7 years in La Plata, Buenos Aires

Introducción. El plomo es un metal tóxico, que, aun en bajas concentraciones sanguíneas, es capaz de alterar el normal desarrollo neurológico de los niños, por lo que no existe un nivel aceptable de plombemia. La absorción de plomo de los alimentos es la mayor contribución a los niveles de plombemia de la población no expuesta laboralmente o a ambientes contaminados. El objetivo fue determinar la contribución dietaria a la exposición al plomo en niños de 1 a 7 años de edad que concurrían por controles de salud al Hospital de Niños de La Plata. Población y métodos. El estudio se realizó entre junio de 2015 y mayo de 2016. Se realizó un cuestionario de frecuencia de consumo de alimentos sobre 91 niños cuya edad promedio ± desvío estándar fue de 3,0 ± 1,7 años, sobre la cual se seleccionaron los alimentos por analizar. Se compraron los alimentos seleccionados en diversos comercios de la región. Se armaron muestras compuestas de diversos grupos de alimentos. Se determinó la concentración de plomo en los grupos de alimentos y, finalmente, se estimó la ingesta diaria de plomo de la población estudiada. Resultados. La ingesta diaria de plomo fue de 138 µg/día.Los grupos de alimentos que tuvieron mayor contribución fueron los productos cárnicos procesados (15,4%), los panificados (14,8%), la leche (12,5%) y la carne (11,7%). Conclusiones. Los niños de 1 a 7 años que concurren a un hospital público de La Plata tienen una carga de plomo en la dieta de 138 µg/día.Introduction. Lead is a toxic metal which, even at low blood levels, can alter normal neurodevelopment in children, so no blood lead level is acceptable. Lead absorption from diet accounts for the highest contribution to blood lead levels in the population who is not exposed to contaminated environments or because of their occupation. The objective of this study was to determine the contribution of diet to lead exposure among children aged 1 to 7 years who attended Hospital de Niños de La Plata for health check-ups. Population and methods. The study was conducted between June 2015 and May 2016. A questionnaire on the frequency of food intake was administered to 91 children whose average age ± standard deviation was 3.0 ± 1.7 years, and foods included in the analysis were selectedbased on this questionnaire. Selected foods were purchased from different regional stores. Composite samples were made up of different food groups. Lead levels corresponding to each food group were determined and, finally, the daily intake of lead was estimated for the studied population. Results. The daily intake of lead was 138 µg/day. The food groups with the higher intake rates were processed meat products (15.4%), bakery products (14.8%), milk (12.5%), and meat (11.7%). Conclusions. Children aged 1 to 7 years attending a public hospital in La Plata have a lead burden from dietary intake of 138 µg/day.Facultad de Ciencias ExactasCentro de Investigación y Desarrollo en Ciencias AplicadasCentro de Investigaciones del Medioambient

Venoarterial PCO₂-to-arteriovenous oxygen content difference ratio is a poor surrogate for anaerobic metabolism in hemodilution: an experimental study

Background: The identification of anaerobic metabolism in critically ill patients is a challenging task. Observational studies have suggested that the ratio of venoarterial PCO2 (Pv–aCO2) to arteriovenous oxygen content difference (Ca–vO2) might be a good surrogate for respiratory quotient (RQ). Yet Pv–aCO2/Ca–vO2 might be increased by other factors, regardless of anaerobic metabolism. At present, comparisons between Pv–aCO2/Ca–vO2 and RQ have not been performed. We sought to compare these variables during stepwise hemorrhage and hemodilution. Since anemia predictably produces augmented Pv–aCO2 and decreased Ca–vO2, our hypothesis was that Pv–aCO2/Ca–vO2 might be an inadequate surrogate for RQ. Methods: This is a subanalysis of a previously published study. In anesthetized and mechanically ventilated sheep (n = 16), we compared the effects of progressive hemodilution and hemorrhage by means of expired gases analysis. Results: There were comparable reductions in oxygen consumption and increases in RQ in the last step of hemodilution and hemorrhage. The increase in Pv–aCO2/Ca–vO2 was higher in hemodilution than in hemorrhage (1.9 ± 0.2 to 10.0 ± 0.9 vs. 1.7 ± 0.2 to 2.5 ± 0.1, P < 0.0001). The increase in Pv–aCO2 was lower in hemodilution (6 ± 0 to 10 ± 1 vs. 6 ± 0 to 17 ± 1 mmHg, P < 0.0001). Venoarterial CO2 content difference and Ca–vO2 decreased in hemodilution and increased in hemorrhage (2.6 ± 0.3 to 1.2 ± 0.1 vs. 2.8 ± 0.2 to 6.9 ± 0.5, and 3.4 ± 0.3 to 1.0 ± 0.3 vs. 3.6 ± 0.3 to 6.8 ± 0.3 mL/dL, P < 0.0001 for both). In hemodilution, Pv–aCO2/Ca–vO2 increased before the fall in oxygen consumption and the increase in RQ. Pv–aCO2/Ca–vO2 was strongly correlated with Hb (R2 = 0.79, P < 0.00001) and moderately with RQ (R2 = 0.41, P < 0.0001). A multiple linear regression model found Hb, RQ, base excess, and mixed venous oxygen saturation and PCO2 as Pv–aCO2/Ca–vO2 determinants (adjusted R2 = 0.86, P < 0.000001). Conclusions: In hemodilution, Pv–aCO2/Ca–vO2 was considerably increased, irrespective of the presence of anaerobic metabolism. Pv–aCO2/Ca–vO2 is a complex variable, which depends on several factors. As such, it was a misleading indicator of anaerobic metabolism in hemodilution.Facultad de Ciencias Médica

Microcirculatory alterations are more severe in anemic than in ischemic hypoxia

The intestinal mucosal-arterial PCO2 (ΔPCO2) remains remarkably stable in anemic hypoxia suggesting that the villi perfusion is well-maintained. The microcirculation, however, has been insufficiently studied in extreme hemodilution.Facultad de Ciencias Médica