Delta de CO2 como estrategia del manejo integral del paciente con choque séptico en la UCI / CO2 delta as a strategy for the comprehensive management of patients with septic shock in the ICU / Delta CO2 como estratégia para o tratamento integral do paciente com choque séptico na UTI

Resumen: Introducción: el choque séptico es un subconjunto de sepsis en el que las anomalías circulatorias, celulares y metabólicas subyacentes son lo suficientemente profundas para aumentar de manera sustancial la mortalidad. Estos pacientes pueden ser identificados en un contexto clínico de choque séptico con hipotensión persistente. La importancia de vigilar valores de delta de pCO2 (presión parcial de dióxido de carbono) de 6 mmHg sirve como herramienta complementaria para evaluar el flujo sanguíneo adecuado hacia la demanda metabólica global. Objetivo: demostrar que el delta de pCO2 es útil en el manejo integral del paciente con choque séptico en la unidad de cuidados intensivos para dirigir el tratamiento de acuerdo con este biomarcador, que se registró al ingreso y a las 24 horas, se relacionaron al pronóstico y a la mortalidad en choque séptico. Material y métodos: estudio descriptivo, ambispectivo, longitudinal y analítico. El universo se compuso de los pacientes que ingresaron a la Unidad de Cuidados Intensivos del Hospital General «La Villa¼ y del Hospital General «Dr. Rubén Leñero¼. Diseño de la maniobra: se tomaron gasometrías arterial y venosa de los pacientes que ingresaron a la UCI, se calculó el delta de pCO2 para ver si los valores de este biomarcador estaban por arriba o debajo de 6 mmHg, ya que un delta de pCO2 se relaciona con mortalidad; sin embargo, el delta de pCO2 se comparó contra el lactato para correlacionar niveles mayores de lactato de 2 mmol/L con la mortalidad. y finalmente observar cuál de los dos biomarcadores es más útil. Se utilizó estadística descriptica para los resultados. Conclusión: de acuerdo a los resultados encontrados en este estudio, se puede decir que el delta de pCO2 y el lactato predijeron el fallecimiento de 15%, lo cual tiene una significancia positiva débil (p = 0.245).

Abstract: Introduction: septic shock is a subset of sepsis in which underlying circulatory, cellular, and metabolic abnormalities are profound enough to substantially increase mortality. These patients can be identified in a clinical setting of septic shock with persistent hypotension. The importance of monitoring delta pCO2 values of 6 mmHg serves as a complementary tool to assess adequate blood flow towards global metabolic demand. Objective: to demonstrate that the pCO2 delta is useful in the comprehensive management of patients with septic shock in the Intensive Care Unit to direct the treatment according to this biomarker (pCO2 delta) that was recorded at admission and at 24 hours, were related to prognosis and mortality in septic shock. Material and methods: descriptive, ambispective, longitudinal and analytical study. The universe was made up of patients admitted to the ICU of the La Villa and Rubén Leñero General Hospitals. Maneuver design: arterial and venous blood gases were taken from the patients admitted to the ICU, the pCO2 delta was calculated to see if the values of this biomarker were above or below 6 mmHg, since a pCO2 delta is related to with mortality; however, delta pCO2 was compared against Lactate to correlate lactate levels greater than two with mortality and finally see which of the two biomarkers is more useful. Descriptive statistics were used for the results. Conclusion: according to the results found in this study, it can be said that delta pCO2 and lactate predicted the death of 15%, which has a weak positive significance (p = 0.245).

Resumo: Introdução: choque séptico é um subconjunto de sepse em que anormalidades circulatórias, celulares e metabólicas subjacentes são profundas o suficiente para aumentar substancialmente a mortalidade, esses pacientes podem ser identificados em um cenário clínico de choque séptico com hipotensão persistente. A importância do monitoramento de valores Delta de pCO2 de 6 mmHg serve como ferramenta complementar para avaliar o fluxo sanguíneo adequado à demanda metabólica global. Objetivo: demonstrar que o Delta pCO2 é útil no manejo integral de pacientes com choque séptico na Unidade de Terapia Intensiva para direcionar o tratamento de acordo com este biomarcador (Delta pCO2) que foi registrado na admissão e em 24 horas, relacionado ao prognóstico e mortalidade no choque séptico. Material e métodos: estudo descritivo, ambispectivo, longitudinal e analítico. O universo foi constituído pelos pacientes internados na UTI dos Hospitais Gerais La Villa e Rubén Leñero. Desenho da estratégia: foram coletadas gasometrias arteriais e venosas dos pacientes internados na UTI, o Delta pCO2 foi calculado para ver se os valores desse biomarcador estavam acima ou abaixo de 6 mmHg, pois um Delta pCO2 está relacionado com mortalidade; entretanto, Delta pCO2 foi comparado com Lactato para correlacionar níveis de lactato maiores que 2 com mortalidade e finalmente observar qual dos dois biomarcadores é mais útil. Foram usadas estatísticas descritivas para os resultados. Conclusão: de acordo com os resultados encontrados neste estudo, pode-se dizer que Delta pCO2 e Lactato predizem óbito em 15%, o que tem uma fraca significância positiva (p = 0.245).

Capnography in newborns under mechanical ventilation and its relationship with the measurement of CO2 in blood samples.

INTRODUCTION: Monitoring the partial pressure of CO2 (PCO2) in newborns who require ventilation would allow avoiding hypocapnia and hypercapnia. The measurement of end-tidal carbon dioxide (ETCO2) is an alternative rarely implemented in this population. OBJECTIVE: To evaluate the relationship between ETCO2 and PCO2 in newborns. METHODS: Cross-sectional study comparing two PCO2 measurement methods, the conventional one by analysis of blood samples and the one estimated by ETCO2. The study included hospitalized newborns that required conventional mechanical ventilation. The ETCO2 was measured with a Tecme GraphNet® neo, a neonatal ventilator with an integrated capnograph, and we obtained the ETCO2-PCO2 gradient. We conducted correlation and Bland-Altman plot analyses to estimate the agreement. RESULTS: A total of 277 samples (ETCO2 / PCO2) from 83 newborns were analyzed. The mean values ​​of ETCO2 and PCO2 were 41.36mmHg and 42.04mmHg. There was a positive and significant correlation between ETCO2 and PCO2 in the overall analysis (r=0.5402; P<.001) and in the analysis of each unit (P<.001). The mean difference was 0.68 mmHg (95% CI, -0.68 to 1.95) and was not significant. We observed a positive systematic error (PCO2 > ETCO2) in 2 of the units, and a negative difference in the third (PCO2 < ETCO2). DISCUSSION: The correlation between ETCO and PCO2 was significant, although the obtained values ​​were not equivalent, with differences ranging from 0.1mmHg and 20mmHg. Likewise, we found systematic errors that differed in sign (positive or negative) between institutions.

Does pH variation influence the toxicity of organic contaminants in estuarine sediments? Effects of Irgarol on nematode assemblages.

Natural pH values in coastal waters vary largely among locations, ecosystems, and time periods; still, there is an ongoing acidification trend. In this scenario, more acidic pH values can alter bioavailability of organic contaminants, to organisms. Despite this, interactive effects between pH and chemical substances are not usually considered in Ecological Risk Assessment protocols. This study investigated the effects of pH on the toxicity of a hydrophobic organic compound on a benthic community using a microcosm experiment setup to assess the response of nematode assemblages exposed to environmentally relevant concentrations of Irgarol at two natural pH conditions. Estuarine nematode assemblages were exposed to two concentrations of Irgarol at pH 7.0 and 8.0 for periods of 7 and 35 days. Lower diversity of nematode genera was observed at the highest tested Irgarol concentration (1281 ± 65 ng.g-1). The results showed that the effects of Irgarol contamination were independent of pH variation, indicating no influence of acidification within this range on the toxicity of Irgarol to benthic meiofauna. However, the results showed that estuarine nematode assemblages are impacted by long-term exposure to low (but naturally occurring) pHs. This indicates that estuarine organisms may be under naturally high physiological pressure and that permanent changes in the ecosystem's environmental factors, such as future coastal ocean acidification, may drive organisms closer to the edges of their tolerance windows.

Early Abnormalities in Gas Exchange in Infants with Congenital Diaphragmatic Hernia.

OBJECTIVE: To determine how blood gas exchange is altered during the transition in the first hour of life in infants with congenital diaphragmatic hernia (CDH). STUDY DESIGN: This was a prospective observational cohort study evaluating arterial blood gas (ABG) samples and ventilator support in 34 infants with CDH in the first hour of life. Infants were stratified into mild, moderate, and severe CDH. The first ABG was compared with the umbilical cord ABGs and response to intervention evaluated on subsequent ABGs among infants with different CDH severities. RESULTS: Infants were intubated at a median of 120 seconds (range 50-240 seconds) and ABGs obtained at a median of 6 minutes (IQR 4, 8 minutes), 16 minutes (IQR 13.5, 22.5 minutes), and 60 minutes (IQR 56, 64 minutes). Compared with the cord ABG, first ABG mean partial pressure of carbon dioxide (PaCO2) increased from 49.8 mm Hg to 82.1 mm Hg, mean base deficit decreased from -2.2 to -7.3, and mean pH from 7.298 to 7.060. With ventilator adjustments, second mean PaCO2 decreased to 76.7 mm Hg and third mean PaCO2 48.5 mm Hg. When stratified, with all CDH severities PaCO2 increased abruptly, remained elevated in moderate and severe CDH, and improved in all severities by 60 minutes after delivery. CONCLUSIONS: Gas exchange is markedly altered in the first hour of life in infants with CDH with abrupt onset of acidemia and a mixed respiratory and metabolic acidosis. Early implementation of adequate cardiopulmonary support may contribute to more timely stabilization of gas exchange.

Estimating spatial and temporal variation in ocean surface pCO2 in the Gulf of Mexico using remote sensing and machine learning techniques.

Research on the carbon cycle of coastal marine systems has been of wide concern recently. Accurate knowledge of the temporal and spatial distributions of sea-surface partial pressure (pCO2) can reflect the seasonal and spatial heterogeneity of CO2 flux and is, therefore, essential for quantifying the ocean's role in carbon cycling. However, it is difficult to use one model to estimate pCO2 and determine its controlling variables for an entire region due to the prominent spatiotemporal heterogeneity of pCO2 in coastal areas. Cubist is a commonly-used model for zoning; thus, it can be applied to the estimation and regional analysis of pCO2 in the Gulf of Mexico (GOM). A cubist model integrated with satellite images was used here to estimate pCO2 in the GOM, a river-dominated coastal area, using satellite products, including chlorophyll-a concentration (Chl-a), sea-surface temperature (SST) and salinity (SSS), and the diffuse attenuation coefficient at 490 nm (Kd-490). The model was based on a semi-mechanistic model and integrated the high-accuracy advantages of machine learning methods. The overall performance showed a root mean square error (RMSE) of 8.42 µatm with a coefficient of determination (R2) of 0.87. Based on the heterogeneity of environmental factors, the GOM area was divided into 6 sub-regions, consisting estuaries, near-shores, and open seas, reflecting a gradient distribution of pCO2. Factor importance and correlation analyses showed that salinity, chlorophyll-a, and temperature are the main controlling environmental variables of pCO2, corresponding to both biological and physical effects. Seasonal changes in the GOM region were also analyzed and explained by changes in the environmental variables. Therefore, considering both high accuracy and interpretability, the cubist-based model was an ideal method for pCO2 estimation and spatiotemporal heterogeneity analysis.

Urbanization increases carbon concentration and pCO2 in subtropical streams.

Urbanization growth may alter the hydrologic conditions and processes driving carbon concentrations in aquatic systems through local changes in land use. Here, we explore dissolved carbon concentrations (DIC and DOC) along urbanization gradient in Santa Catarina Island to evaluate potential increase of CO2 in streams. Additionally, we assessed chemical, physical, and biotic variables to evaluate direct and indirect effects of urbanization in watersheds. We defined 3 specific urbanization levels: high (> 15% urbanized area), medium (15-5% urbanized area), and low (< 5% urbanized area) urbanization. The results showed that local changes due to growth of urban areas into watersheds altered the carbon concentrations in streams. DOC and DIC showed high concentrations in higher urbanization levels. The watersheds with an urban building area above 5% showed pCO2 predominantly above the equilibrium with the atmosphere. These findings reveal that local modifications in land use may contribute to changes in global climate by altering the regional carbon balance in streams.

Pharmacological safety of Plinia cauliflora (Mart.) Kausel in rabbits.

Fruit peels of Plinia cauliflora (Mart.) Kausel are widely used in Brazilian traditional medicine, but no studies have proved the safety of its pharmacological effects on the respiratory, cardiovascular, and central nervous systems. The present study assessed the safety pharmacology of P. cauliflora in New Zealand rabbits. First, an ethanol extract (EEPC) was selected for the pharmacological experiments and chemical characterization. Then, different groups of rabbits were orally treated with EEPC (200 and 2000 mg/kg) or vehicle. Acute behavioral and physiological alterations in the modified Irwin test, respiratory rate, arterial blood gas, and various cardiovascular parameters (i.e., heart rate, blood pressure, and electrocardiography) were evaluated. The main secondary metabolites that were identified in EEPC were ellagic acid, gallic acid, O-deoxyhexosyl quercetin, and the anthocyanin O-hexosyl cyanidin. No significant behavioral or physiological changes were observed in any of the groups. None of the doses of EEPC affected respiratory rate or arterial blood gas, with no changes on blood pressure or electrocardiographic parameters. The present study showed that EEPC did not cause any significant changes in respiratory, cardiovascular, or central nervous system function. These data provide scientific evidence of the effects of this species and important safety data for its clinical use.

The energetic physiology of juvenile mussels, Mytilus chilensis (Hupe): The prevalent role of salinity under current and predicted pCO2 scenarios.

As a result of human activities, climate forecasts predict changes in the oceans pCO2 and salinity levels with unknown impacts on marine organisms. As a consequence, an increasing number of studies have begun to address the individual influence of pCO2 and salinity but much remains to be done to understand their combined effects on the physiology and ecology of marine species. Our study addressed this knowledge gap by measuring the influence of current and predicted levels of pCO2 (380 and 1200 ppm, respectively) and salinity (20, 25 and 30 psµ) on the energetic physiology of juvenile mussels (Mytilus chilensis) from the south-eastern Pacific region. Our results indicate that a reduced salinity caused a significant reduction in clearance rate, absorption efficiency and scope for growth of this species. Meanwhile, an increase in pCO2 levels caused a reduction in excretion rates and interacted significantly with salinity in the rate of oxygen uptake measured in the mussel. These results suggest that potential changes in salinity might have a direct role on the physiology of M. chilensis. The effect of pCO2, although less prevalent among the variables measured here, did interact with salinity and is also likely to alter the physiology of this species. Given the ecological and economic importance of M. chilensis, we call for further studies exploring the influence of pCO2 across a wider range of salinities.

Native and exotic oysters in Brazil: Comparative tolerance to hypercapnia.

Environmental hypercapnia in shallow coastal marine ecosystems can be exacerbated by increasing levels of atmospheric CO2. In these ecosystems organisms are expected to become increasingly subjected to pCO2 levels several times higher than those inhabiting ocean waters (e.g.: 10,000µatm), but still our current understanding on different species capacity to respond to such levels of hypercapnia is limited. Oysters are among the most important foundation species inhabiting these coastal ecosystems, although natural oyster banks are increasingly threatened worldwide. In the present study we studied the effects of hypercapnia on two important oyster species, the pacific oyster C. gigas and the mangrove oyster C. brasiliana, to bring new insights on different species response mechanisms towards three hypercapnic levels (ca. 1,000; 4,000; 10,000 µatm), by study of a set of biomarkers related to metabolic potential (electron transport system - ETS), antioxidant capacity (SOD, CAT, GSH), cellular damage (LPO) and energetic fitness (GLY), in two life stages (juvenile and adult) after 28 days of exposure. Results showed marked differences between each species tolerance capacity to hypercapnia, with contrasting metabolic readjustment strategies (ETS), different antioxidant response capacities (SOD, CAT, GSH), which generally allowed to prevent increased cellular damage (LPO) and energetic impairment (GLY) in both species. Juveniles were more responsive to hypercapnia stress in both congeners, and are likely to be most sensitive to extreme hypercapnia in the environment. Juvenile C. gigas presented more pronounced biochemical alterations at intermediate hypercapnia (4,000µatm) than C. brasiliana. Adult C. gigas showed biochemical alterations mostly in response to high hypercapnia (10,000µatm), while adult C. brasiliana were less responsive to this environmental stressor, despite presenting decreased metabolic potential. Our data bring new insights on the biochemical performance of two important oyster species, and suggest that the duration of extreme hypercapnia events in the ecosystem may pose increased challenges for these organisms as their tolerance capacity may be time limited.

Utilidad de los parámetros gasométricos como predictores de mortalidad en pacientes con choque séptico / Usefulness of gasometric parameters as predictors of mortality in septic shock patients / Utilidade dos parâmetros gasométricos como preditores da mortalidade em pacientes com choque séptico

Resumen: Objetivos: Describir los parámetros gasométricos de la presión de dióxido de carbono, el déficit de base y saturación venosa central en los pacientes en choque séptico y observar si el cambio entre el valor inicial (T0) y a las 24 horas (T1) influye en su pronóstico. Material y métodos: Se realizó un estudio observacional y retrospectivo desde marzo de 2014 a julio de 2016 en pacientes mayores de 18 años con diagnóstico de choque séptico. Se midieron SOFA y APACHE II al ingreso, así como las variables derivadas de las gasometrías venosa central y arterial al diagnóstico del choque séptico (T0) y a las 24 horas del manejo inicial (T1). Resultados: Se incluyeron 39 pacientes: sobrevivientes (n = 25) y no sobrevivientes (n = 14). Al ingreso (T0), hubo diferencias entre ambos grupos en la ΔPCO2 y ΔPCO2/Ca-vO2 (7.2 ± 2.4 versus 8.7 ± 2.0 mmHg, p = 0.05) y (1.7 ± 0.5 versus 2.1 ± 0.9 mmHg/mL, p = 0.05), respectivamente. A las 24 horas (T1), el déficit de base (DB) y la presión arterial media (PAM) mostraron diferencia entre los grupos (-4.5 ± 5.0 versus -9.5 ± 7.7 mEq/L, p = 0.02) y (81 ± 10 versus 70 ± 9 mmHg, p = 0.03). El cambio del déficit de base (ΔDB) entre los valores al ingreso (T0) y a las 24 horas (T1) fue significativo (-4.5 ± 4.1 versus 2.1 ± 6.3 mEq/L, p = 0.001); en la razón ΔPCO2/Ca-vO2 (ΔRatio) no hubo diferencia (-0.02 ± 1.2 versus 0.72 ± 1.7 mmHg/mL, p = 0.13) entre los grupos. Conclusión: Además de la ΔPCO2 y la razón ΔPCO2/Ca-vO2, en este estudio, el déficit de base puede ser una herramienta pronóstica en los pacientes con choque séptico.

Abstract: Objectives: To describe the carbon dioxide parameters, base deficit and central venous saturation in septic shock patients and observe if the change between the initial value (T0) and at 24 hours (T1) influences their prognosis. Material and methods: We performed a retrospective and observational study from March 2014 to July 2016. We included patients at least 18 years old with septic shock diagnosis. We assessed SOFA and APACHE II at admission and the derived gasometric parameters at diagnosis of septic shock and at 24 hours of treatment. Results: We included 39 patients. Survivors (n = 25) and non-survivors (n = 14). Upon admission (T0) there were differences between both groups in ΔPCO2 and ΔPCO2/Ca-vO2 (7.2 ± 2.4 versus 8.7 ± 2.0 mmHg, p = 0.05) and (1.7 ± 0.5 versus 2.1 ± 0.9 mmHg/mL, p = 0.05), respectively. At 24 hours (T1) base deficit (BD) and mean arterial pressure (MAP) showed significant differences (-4.5 ± 5.0 versus -9.5 ± 7.7 mEq/L, p = 0.02) and (81 ± 10 versus 70 ± 9 mmHg, p = 0.03). The change in BD (ΔBD) between (T0) and (T1) was significant (-4.5 ± 4.1 versus 2.1 ± 6.3 mEq/L, p = 0.001) and ΔPCO2/Ca-vO2 ratio (ΔRatio) showed no difference (-0.02 ± 1.2 versus 0.72 ± 1.7 mmHg/mL, p = 0.13) among the groups. Conclusions: Beside ΔPCO2 and ΔPCO2/Ca-vO2 ratio, base deficit can be a prognostic instrument in patients with septic shock.

Resumo: Objetivo: Descrever os parâmetros gasométricos da pressão do dióxido de carbono, o deficit de base e a saturação venosa central em pacientes com choque séptico e observar se a variação entre o valor inicial (T0) e às 24 horas (T1) influencia o prognóstico dos pacientes. Material e métodos: Estudo retrospectivo e observacional desde março de 2014 a julho de 2016 em pacientes com idade superior a 18 anos com diagnóstico de choque séptico. Foram medidos SOFA escore e APACHE II na admissão, bem como as variáveis derivadas a partir da gasometria venosa central e arterial ao diagnóstico de choque séptico (T0) e às 24 horas do tratamento inicial (T1). Resultados: Foram incluídos 39 pacientes: sobreviventes (n = 25) e não sobreviventes (n = 14). Na admissão (T0), existem diferenças entre sobreviventes contra os não sobreviventes na ΔPCO2 e ΔPCO2/Ca-vO2 (7.2 ± 2.4 vs 8.7 ± 2.0 mmHg, p = 0.05) e (1.7 ± 0.5 vs 2.1 ± 0.9 mmHg/mL, p = 0.05), respectivamente. Após 24 horas (T1) o défice de base (DB) e a PAM mostraram diferenças entre os grupos (-4.5 ± 5.0 vs -9.5 ± 7.7 mEq / L, p = 0.02) e (81 ± 10 vs 70 ± 9 mmHg, p = 0.03). O delta DB entre os valores de admissão (T0) e às 24 horas (T1) foi significativa (-4.5 ± 4.1 vs 2.1 ± 6.3 mEq/L, p = 0.001) e na razão ΔPCO2/Ca-vO2 (ΔRatio) não houve diferença entre os grupos (-0.02 ± 1.2 vs 0.72 ± 1.7 mmHg/mL, p = 0.13). Conclusão: Ademais da ΔPCO2 e a razão ΔPCO2/Ca-vO2, neste estudo, o deficit de base pode ser uma ferramenta prognóstica em pacientes com choque séptico.

A hypoperfusion context may aid to interpret hyperlactatemia in sepsis-3 septic shock patients: a proof-of-concept study.

BACKGROUND: Persistent hyperlactatemia is particularly difficult to interpret in septic shock. Besides hypoperfusion, adrenergic-driven lactate production and impaired lactate clearance are important contributors. However, clinical recognition of different sources of hyperlactatemia is unfortunately not a common practice and patients are treated with the same strategy despite the risk of over-resuscitation in some. Indeed, pursuing additional resuscitation in non-hypoperfusion-related cases might lead to the toxicity of fluid overload and vasoactive drugs. We hypothesized that two different clinical patterns can be recognized in septic shock patients through a multimodal perfusion monitoring. Hyperlactatemic patients with a hypoperfusion context probably represent a more severe acute circulatory dysfunction, and the absence of a hypoperfusion context is eventually associated with a good outcome. We performed a retrospective analysis of a database of septic shock patients with persistent hyperlactatemia after initial resuscitation. RESULTS: We defined hypoperfusion context by the presence of a ScvO2 < 70%, or a P(cv-a)CO2 ≥6 mmHg, or a CRT ≥4 s together with hyperlactatemia. Ninety patients were included, of whom seventy exhibited a hypoperfusion-related pattern and 20 did not. Although lactate values were comparable at baseline (4.8 ± 2.8 vs. 4.7 ± 3.7 mmol/L), patients with a hypoperfusion context exhibited a more severe circulatory dysfunction with higher vasopressor requirements, and a trend to longer mechanical ventilation days, ICU stay, and more rescue therapies. Only one of the 20 hyperlactatemic patients without a hypoperfusion context died (5%) compared to 11 of the 70 with hypoperfusion-related hyperlactatemia (16%). CONCLUSIONS: Two different clinical patterns among hyperlactatemic septic shock patients may be identified according to hypoperfusion context. Patients with hyperlactatemia plus low ScvO2, or high P(cv-a)CO2, or high CRT values exhibited a more severe circulatory dysfunction. This provides a starting point to launch further prospective studies to confirm if this approach can lead to a more selective resuscitation strategy.

Validation protocol for multiple blood gas analyzers in accordance with laboratory accreditation programs / Protocolo de validação de múltiplos equipamentos para análise de gases sanguíneos em conformidade com os programas de acreditação laboratorial

ABSTRACTIntroduction:The results of blood gas analysis using different instrumentation can vary widely due to the methodological differences, the calibration procedures and the use of different configurations for each type of instrument.Objective:The objective of this study was to evaluate multiple analytical systems for measurement of blood gases, electrolytes and metabolites in accordance with the accreditation program (PALC) of Sociedade Brasileira de Patologia Clínica/Medicina Laboratorial (SBPC/ML).Materials and methods:20 samples were evaluated in three ABL800 Flex (Radiometer Medical ApS, Denmark) blood gas analyzers, and the results were compared with those of the device in use, which was considered the reference. The analysis of variance (Anova) was applied for statistical purposes, as well as the calculation of mean, standard deviation and coefficient of variation.Results:The p values obtained in the statistical analysis were: pH = 0.983, pO2 = 0.991, pCO2 = 0.353, lactate = 0.584, glucose = 0.995, ionized calcium = 0.983, sodium = 0.991, potassium = 0.926, chlorine = 0.029.Conclusion:The evaluation of multiple analytical systems is an essential procedure in the clinical laboratory for quality assurance and accuracy of the results.

RESUMOIntrodução:Os resultados da análise dos gases sanguíneos utilizando diferentes equipamentos podem apresentar grandes variações decorrentes das diferenças metodológicas, dos procedimentos de calibração e da aplicação de configurações distintas para cada tipo de instrumento.Objetivo:O objetivo deste trabalho foi avaliar múltiplos sistemas analíticos para teste de gases sanguíneos, eletrólitos e metabólitos, em conformidade com o Programa de Acreditação de Laboratórios Clínicos (PALC) da Sociedade Brasileira de Patologia Clínica/Medicina Laboratorial (SBPC/ML).Materiais e métodos:Foram avaliadas 20 amostras em três analisadores de gases sanguíneos ABL800 Flex (Radiometer Medical ApS, Dinamarca) em relação ao equipamento em uso, que foi considerado referência. A análise de variância (Anova) foi aplicada para fins de estudo estatístico dos resultados obtidos nos quatro equipamentos, bem como o cálculo da média, do desvio padrão e do coeficiente de variação.Resultados:Os valores de p obtidos na análise estatística foram: pH = 0,983, pO2 = 0,991, pCO2 = 0,353, lactato = 0,584, glicose = 0,995, cálcio ionizado = 0,983, sódio = 0,991, potássio = 0,926 e cloro = 0,029.Conclusão:A avaliação de múltiplos sistemas analíticos é procedimento essencial no laboratório clínico para garantia da qualidade e da exatidão dos resultados.

Diurnal sampling reveals significant variation in CO2 emission from a tropical productive lake / Amostragem diurna demonstra variação significativa na emissão de CO2 em um lago tropical produtivo

It is well accepted in the literature that lakes are generally net heterotrophic and supersaturated with CO2 because they receive allochthonous carbon inputs. However, autotrophy and CO2 undersaturation may happen for at least part of the time, especially in productive lakes. Since diurnal scale is particularly important to tropical lakes dynamics, we evaluated diurnal changes in pCO2 and CO2 flux across the air-water interface in a tropical productive lake in southeastern Brazil (Lake Carioca) over two consecutive days. Both pCO2 and CO2 flux were significantly different between day (9:00 to 17:00) and night (21:00 to 5:00) confirming the importance of this scale for CO2 dynamics in tropical lakes. Net heterotrophy and CO2 outgassing from the lake were registered only at night, while significant CO2 emission did not happen during the day. Dissolved oxygen concentration and temperature trends over the diurnal cycle indicated the dependence of CO2 dynamics on lake metabolism (respiration and photosynthesis). This study indicates the importance of considering the diurnal scale when examining CO2 emissions from tropical lakes.(AU)

É amplamente aceito na literatura que lagos são em geral heterotróficos e supersaturados com CO2 já que recebem carbono alóctone. Porém, autotrofia e insaturação de CO2 podem ocorrer em pelo menos parte do tempo, especialmente em lagos produtivos. Como a escala diurna é particularmente importante para a dinâmica de lagos tropicais, variações diurnas na pCO2 e no fluxo de CO2 através da interface ar-água foram avaliadas num lago tropical produtivo do sudeste do Brasil (Lagoa Carioca) durante dois dias consecutivos. Tanto a pCO2 quanto o fluxo de CO2 foram significativamente diferentes entre o dia (9:00 às 17:00) e a noite (21:00 às 5:00), confirmando a influência desta escala na dinâmica do CO2 na Lagoa Carioca. Foram registradas heterotrofia e emissão de CO2 pela lagoa apenas durante a noite, enquanto durante o dia não houve emissão significativa. Variações na concentração de oxigênio dissolvido e na temperatura ao longo do dia indicaram a dependência da dinâmica do CO2 no metabolismo (respiração e fotossíntese) deste lago. Este estudo indica a importância de se considerar a escala diurna na avaliação da emissão de CO2 por lagos tropicais.(AU)

Diurnal sampling reveals significant variation in CO2 emission from a tropical productive lake

It is well accepted in the literature that lakes are generally net heterotrophic and supersaturated with CO2 because they receive allochthonous carbon inputs. However, autotrophy and CO2undersaturation may happen for at least part of the time, especially in productive lakes. Since diurnal scale is particularly important to tropical lakes dynamics, we evaluated diurnal changes in pCO2and CO2 flux across the air-water interface in a tropical productive lake in southeastern Brazil (Lake Carioca) over two consecutive days. Both pCO2 and CO2 flux were significantly different between day (9:00 to 17:00) and night (21:00 to 5:00) confirming the importance of this scale for CO2 dynamics in tropical lakes. Net heterotrophy and CO2 outgassing from the lake were registered only at night, while significant CO2 emission did not happen during the day. Dissolved oxygen concentration and temperature trends over the diurnal cycle indicated the dependence of CO2 dynamics on lake metabolism (respiration and photosynthesis). This study indicates the importance of considering the diurnal scale when examining CO2emissions from tropical lakes.

É amplamente aceito na literatura que lagos são em geral heterotróficos e supersaturados com CO2 já que recebem carbono alóctone. Porém, autotrofia e insaturação de CO2 podem ocorrer em pelo menos parte do tempo, especialmente em lagos produtivos. Como a escala diurna é particularmente importante para a dinâmica de lagos tropicais, variações diurnas na pCO2 e no fluxo de CO2 através da interface ar-água foram avaliadas num lago tropical produtivo do sudeste do Brasil (Lagoa Carioca) durante dois dias consecutivos. Tanto a pCO2 quanto o fluxo de CO2 foram significativamente diferentes entre o dia (9:00 às 17:00) e a noite (21:00 às 5:00), confirmando a influência desta escala na dinâmica do CO2 na Lagoa Carioca. Foram registradas heterotrofia e emissão de CO2 pela lagoa apenas durante a noite, enquanto durante o dia não houve emissão significativa. Variações na concentração de oxigênio dissolvido e na temperatura ao longo do dia indicaram a dependência da dinâmica do CO2 no metabolismo (respiração e fotossíntese) deste lago. Este estudo indica a importância de se considerar a escala diurna na avaliação da emissão de CO2 por lagos tropicais.

Diurnal sampling reveals significant variation in CO2 emission from a tropical productive lake / Amostragem diurna demonstra variação significativa na emissão de CO2 em um lago tropical produtivo

It is well accepted in the literature that lakes are generally net heterotrophic and supersaturated with CO2 because they receive allochthonous carbon inputs. However, autotrophy and CO2 undersaturation may happen for at least part of the time, especially in productive lakes. Since diurnal scale is particularly important to tropical lakes dynamics, we evaluated diurnal changes in pCO2 and CO2 flux across the air-water interface in a tropical productive lake in southeastern Brazil (Lake Carioca) over two consecutive days. Both pCO2 and CO2 flux were significantly different between day (9:00 to 17:00) and night (21:00 to 5:00) confirming the importance of this scale for CO2 dynamics in tropical lakes. Net heterotrophy and CO2 outgassing from the lake were registered only at night, while significant CO2 emission did not happen during the day. Dissolved oxygen concentration and temperature trends over the diurnal cycle indicated the dependence of CO2 dynamics on lake metabolism (respiration and photosynthesis). This study indicates the importance of considering the diurnal scale when examining CO2 emissions from tropical lakes.

É amplamente aceito na literatura que lagos são em geral heterotróficos e supersaturados com CO2 já que recebem carbono alóctone. Porém, autotrofia e insaturação de CO2 podem ocorrer em pelo menos parte do tempo, especialmente em lagos produtivos. Como a escala diurna é particularmente importante para a dinâmica de lagos tropicais, variações diurnas na pCO2 e no fluxo de CO2 através da interface ar-água foram avaliadas num lago tropical produtivo do sudeste do Brasil (Lagoa Carioca) durante dois dias consecutivos. Tanto a pCO2 quanto o fluxo de CO2 foram significativamente diferentes entre o dia (9:00 às 17:00) e a noite (21:00 às 5:00), confirmando a influência desta escala na dinâmica do CO2 na Lagoa Carioca. Foram registradas heterotrofia e emissão de CO2 pela lagoa apenas durante a noite, enquanto durante o dia não houve emissão significativa. Variações na concentração de oxigênio dissolvido e na temperatura ao longo do dia indicaram a dependência da dinâmica do CO2 no metabolismo (respiração e fotossíntese) deste lago. Este estudo indica a importância de se considerar a escala diurna na avaliação da emissão de CO2 por lagos tropicais.

Valores de referencia de gases arteriales y de electrolitos en caninos de la sabana de Bogotá / Reference Values of Arterial Gases and Electrolytes in Canines from the Bogotá Savanna / Valores de referência de gases arteriais e de eletrólitos em caninos da savana de Bogotá

Debido a la ausencia de valores de gasometría arterial que se ajusten a nuestras condiciones ambientales y a la amplia variedad de datos no actualizados en la literatura y utilizados en la práctica diaria, obtenidos con alturas, razas y equipos diferentes a los disponibles en nuestro medio, es necesario generar conocimiento propio ajustado a nuestra realidad. Se realizó una medición sistemática al azar de sangre arterial y venosa en 100 caninos sanos a la altura de la sabana de Bogotá (Chía: 2652 msnm; Cajicá: 2558 msnm; Sopó: 2650 msnm; La Calera: 2718 msnm y Bogotá: 2630 msnm), utilizando el analizador I-STAT® con cartucho EG7+. Se encontraron valores de referencia de gasometría, electrolitos, bases efectivas y pH. Los valores fueron comparados entre cuatro grupos por peso. Para cada parámetro se realizó estadística descriptiva basada en promedio, desviación estándar, error estándar, y se hallaron los límites de confianza (95%) y los intervalos con desviación estándar (una y dos desviaciones). Se evidenció disminución de PCO2, PO2, SO2, bicarbonato, BE. El pH se encontró levemente aumentado, similar a lo reportado por autores a grandes alturas y diferentes (no corroborado estadísticamente) a reportes en literatura, en los que la altura no fue una variable. Aun así son usados frecuentemente como referencia en la práctica de pequeños animales; solo la presentó diferencias estadísticas por grupos de peso. Como conclusión, se evidenció una regulación del pH sanguíneo eficaz a 2600 msnm, con diferentes valores de bicarbonato, PCO2, PO2, BE, que indican la necesidad de obtener y utilizar valores de referencia acordes con condiciones locales.

Due to the lack of arterial gas values that meet our environmental conditions and the wide variety of out-of-date data in literature and used in everyday practice, obtained with different heights, breeds and equipment to the ones available in our context, it becomes necessary to generate our own knowledge adjusted to our reality. A random systematic measurement of arterial and venous blood was made on 100 healthy canines in the Bogotá Savanna (Chia: 2652 m.a.s.l.; Cajica: 2558 m.a.s.l.; Sopo: 2650 m.a.s.l.; La Calera: 2718 m.a.s.l.; and Bogotá: 2630 m.a.s.l.;), using the I-STAT® analyzer with EG7+ cartridge. Reference values were found for gasometry, electrolytes, effective basis and pH. The values were compared between four groups by weight. Descriptive statistics were made for each parameter based on average, standard deviation and standard error, and the trust limits (95%) and the intervals with standard deviation (one and two deviations) were found. A decrease on PCO2, PO2, SO2, bicarbonate and BE was evident. The pH was found to be slightly increased, similar to the one reported by authors at great heights and different (not statistically confirmed) from reports in literature, where height was not a variable. Even so, they are frequently used as reference in the practice of small animals; only PO2 presented statistical differences by groups of weight. As a conclusion, effective regulation of blood pH was evident at 2600 m.a.s.l., with different bicarbonate values, PCO2, PO2, BE, which suggest the need to obtain and use reference values consistent with local conditions.

Devido à ausência de valores de gasometria arterial que se ajuste a nossas condições ambientais e à ampla variedade de dados não atualizados na literatura e utilizados na prática diária, obtidos com alturas, raças e equipes diferentes aos disponíveis em nosso meio, é necessário gerar conhecimento próprio ajustado a nossa realidade. Realizou-se uma medição sistemática ao azar de sangue arterial e venoso em 100 caninos sãos à altura da savana de Bogotá (Chia: 2652 msnm; Cajicá: 2558 msnm; Sopó: 2650 msnm; a Calera: 2718 msnm e Bogotá: 2630 msnm), utilizando o analisador I-STAT® com cartucho EG7+. Encontraram-se valores de referência de gasometria, eletrólitos, bases efetivas e pH. Os valores foram comparados entre quatro grupos por peso. Para cada parâmetro se realizou estatística descritiva baseada na média, no padrão de desvio, erro padrão, e se encontrou os limites de confiança (95%) e os intervalos com desvio padrão (um e dois desvios). Evidenciou-se diminuição de PCO2, PO2, SO2, bicarbonato, BE. O pH se encontrou levemente aumentado, similar ao reportado por autores a grandes alturas e diferentes (não corroborado estatisticamente) a relatórios em literatura, onde que a altura não foi uma variável.. Ainda assim são usados frequentemente como referência na prática de pequenos animais; só a PO2 apresentou diferenças estatísticas por grupos de peso. Como conclusão, se evidenciou uma regulação do pH sanguíneo eficaz a 2600 msnm, com diferentes valores de bicarbonato, PCO2, PO2, BE, que indicam a necessidade de obter e utilizar valores de referência acordes com condições locais.

Elevated carbon dioxide upregulates NBCn1 Na+/HCO3(-) cotransporter in human embryonic kidney cells.

The NBCn1 Na(+)/HCO3(-) cotransporter catalyzes the electroneutral movement of 1 Na(+):1 HCO3(-) into kidney cells. We characterized the intracellular pH (pHi) regulation in human embryonic kidney cells (HEK) subjected to NH4Cl prepulse acid loading, and we examined the NBCn1 expression and function in HEK cells subjected to 24-h elevated Pco2 (10-15%). After acid loading, in the presence of HCO3(-), ∼50% of the pHi recovery phase was blocked by the Na(+)/H(+) exchanger inhibitors EIPA (10-50 µM) and amiloride (1 mM) and was fully cancelled by 30 µM EIPA under nominally HCO3(-)-free conditions. In addition, in the presence of HCO3(-), pHi recovery after acid loading was completely blocked when Na(+) was omitted in the buffer. pHi recovery after acidification in HEK cells was repeated in the presence of the NBC inhibitor S0859, and the pHi recovery was inhibited by S0859 in a dose-dependent manner (Ki = 30 µM, full inhibition at 60 µM), which confirmed NBC Na(+)/HCO3(-) cotransporter activation. NBCn1 expression increased threefold after 24-h exposure of cultured HEK cells to 10% CO2 and sevenfold after exposure to 15% CO2, examined by immunoblots. Finally, exposure of HEK cells to high CO2 significantly increased the HCO3(-)-dependent recovery of pHi after acid loading. We conclude that HEK cells expressed the NBCn1 Na(+)/HCO3(-) cotransporter as the only HCO3(-)-dependent mechanism responsible for cellular alkaline loading. NBCn1, which expresses in different kidney cell types, was upregulated by 24-h high-Pco2 exposure of HEK cells, and this upregulation was accompanied by increased NBCn1-mediated HCO3(-) transport.

Spatial variation of sediment mineralization supports differential CO2 emissions from a tropical hydroelectric reservoir.

Substantial amounts of organic matter (OM) from terrestrial ecosystems are buried as sediments in inland waters. It is still unclear to what extent this OM constitutes a sink of carbon, and how much of it is returned to the atmosphere upon mineralization to carbon dioxide (CO2). The construction of reservoirs affects the carbon cycle by increasing OM sedimentation at the regional scale. In this study we determine the OM mineralization in the sediment of three zones (river, transition, and dam) of a tropical hydroelectric reservoir in Brazil as well as identify the composition of the carbon pool available for mineralization. We measured sediment organic carbon mineralization rates and related them to the composition of the OM, bacterial abundance and pCO2 of the surface water of the reservoir. Terrestrial OM was an important substrate for the mineralization. In the river and transition zones most of the OM was allochthonous (56 and 48%, respectively) while the dam zone had the lowest allochthonous contribution (7%). The highest mineralization rates were found in the transition zone (154.80 ± 33.50 mg C m(-) (2) d(-) (1)) and the lowest in the dam (51.60 ± 26.80 mg C m(-) (2) d(-) (1)). Moreover, mineralization rates were significantly related to bacterial abundance (r (2) = 0.50, p < 0.001) and pCO2 in the surface water of the reservoir (r (2) = 0.73, p < 0.001). The results indicate that allochthonous OM has different contributions to sediment mineralization in the three zones of the reservoir. Further, the sediment mineralization, mediated by heterotrophic bacteria metabolism, significantly contributes to CO2 supersaturation in the water column, resulting in higher pCO2 in the river and transition zones in comparison with the dam zone, affecting greenhouse gas emission estimations from hydroelectric reservoirs.

Experimental evidence of nitrogen control on pCO(2) in phosphorus-enriched humic and clear coastal lagoon waters.

Natural and human-induced controls on carbon dioxide (CO(2)) in tropical waters may be very dynamic (over time and among or within ecosystems) considering the potential role of warmer temperatures intensifying metabolic responses and playing a direct role on the balance between photosynthesis and respiration. The high magnitude of biological processes at low latitudes following eutrophication by nitrogen (N) and phosphorus (P) inputs into coastal lagoons waters may be a relevant component of the carbon cycle, showing controls on partial pressure of CO(2) (pCO(2)) that are still poorly understood. Here we assessed the strength of N control on pCO(2) in P-enriched humic and clear coastal lagoons waters, using four experimental treatments in microcosms: control (no additional nutrients) and three levels of N additions coupled to P enrichments. In humic coastal lagoons waters, a persistent CO(2) supersaturation was reported in controls and all nutrient-enriched treatments, ranging from 24- to 4-fold the atmospheric equilibrium value. However, both humic and clear coastal lagoons waters only showed significant decreases in pCO(2) in relation to the controlled microcosms in the two treatments with higher N addition levels. Additionally, clear coastal lagoons water microcosms showed a shift from CO(2) sources to CO(2) sinks, in relation to the atmosphere. Only in the two more N-enriched treatments did pCO(2) substantially decrease, from 650 µatm in controls and less N-enriched treatments to 10 µatm in more N-enriched microcosms. Humic substrates and N inputs can modulate pCO(2) even in P-enriched coastal lagoons waters, thereby being important drivers on CO(2) outgassing from inland waters.

Impact of upwelling events on the sea water carbonate chemistry and dissolved oxygen concentration in the Gulf of Papagayo (Culebra Bay), Costa Rica: Implications for coral reefs / Impacto de los eventos de surgencia en la química del carbonato del agua de mar y la concentración de oxígeno disuelto en el Golfo de Papagayo (Bahía Culebra), Costa Rica: Implicaciones para los arrecifes de coral

The Gulf of Papagayo, Pacific coast of Costa Rica, is one of the three seasonal upwelling areas of Mesoamerica. In April 2009, a 29-hour experiment was carried out at the pier of the Marina Papagayo, Culebra Bay. We determined sea surface temperature (SST), dissolved oxygen concentration, salinity, pH, and the partial pressure of CO2 (pCO2). The aragonite saturation state (Ωa) as well as the other parameters of the marine carbonate system such as the total dissolved inorganic carbon (DIC) and the total alkalinity (TA) were calculated based on the measured pH and the pCO2. The entrainment of subsurface waters raised the pCO2 up to 645 µatm. SSTs, dissolved oxygen concentrations decreased form 26.4 to 23.7°C and from 228 to 144 µmol l-1. Ωa dropped down to values of 2.1. Although these changes are assumed to reduce the coral growth, the main reef building coral species within the region (Pocillopora spp. and Pavona clavus) reveal growth rates exceeding those measured at other sites in the eastern tropical Pacific. This implies that the negative impact of upwelling on coral growth might be overcompensated by an enhanced energy supply caused by the high density of food and nutrients and more favorable condition for coral growth during the non-upwelling season.

El Golfo de Papagayo, costa Pacífica de Costa Rica, es una de las tres regiones de afloramiento estacional de Mesoamérica. Las características físicas y químicas del agua que aflora no habían sido estudiadas. Durante 29 horas en Abril 2009, se estudiaron la temperatura superficial del mar (TSM), la concentración de oxígeno disuelto, salinidad, pH y la presión parcial de CO2 (pCO2), en la Marina Papagayo, Bahía Culebra. Con base en las mediciones de pH y pCO2 se calculó el estado de saturación de la aragonita (Ω) y otros parámetros del sistema de carbonatos como lo es el carbono orgánico disuelto (COD) y la alcalinidad total (AT). Los resultados indican que el arrastre por convección del agua sub-superficial durante los eventos de afloramiento aumenta la pCO2 y disminuye la TSM, la concentración de oxígeno disuelto y Ω. Aunque se asume que estas condiciones reducen el crecimiento coralino, las principales especies constructoras de arrecife en la región de Papagayo (Pocillopora spp. y Pavona clavus) tienen las mayores tasas de crecimiento en el Pacífico Tropical Oriental. Esto posiblemente implica que el efecto negativo del afloramiento es compensado por el crecimiento durante la época de no afloramiento.