Fluid balance during taekwondo training / Equilíbrio hídrico durante treinamento de taekwondo / Equilibrio hídrico durante entrenamiento de taekwondo

ABSTRACT Introduction Dehydration has been described as one of the main factors of reduced performance in combat sports activities, leading to death in extreme cases. Objective To investigate the pre-training hydration status and changes in fluid homeostasis during two taekwondo training sessions. Methods Eighteen male college athletes (age 22.6 ± 3.37 years) were assessed. The study design aimed to reproduce the conditions of a 90-minute taekwondo training session, divided into three stages: a) warm-up exercises (20 min); b) poomsae (30 min) and c) technical training (40 min). The athletes had ad libitum water intake during training. To assess the hydration status we considered body mass (BM), the amount of liquid consumed and urine output, which enabled us to establish absolute and relative fluid loss in kg and percentage as well as the sweating rate. We also considered urine specific gravity (USG), urine color (U-COL), and subjective sensation of thirst (Sthirst) before and after the training session. Pre- and post-training results were compared separately in each session and between sessions. Results There was a significant difference (P<0.05) in pre-training BM between the two days of training. There was a significant difference (P<0.05) in the final BM on both days of the experiment. Most subjects had relative dehydration below 2%. A significant difference (P<0.05) was recorded pre and post training for U-COL and Sthirst, with the highest rates obtained at the end of each session. Participants always started training at a low dehydration status (USG >1,020g.ml-1). Conclusions The athletes tended to start the training sessions in dehydration status, which increases over the course of the training. Ad libitum water intake was not sufficient to balance fluid loss. Changes in fluid levels between sessions were similar. Level of Evidence II; Therapeutic Studies Investigating the Results Level of Treatment.

RESUMO Introdução A desidratação tem sido descrita como um dos principais fatores de redução de desempenho em atividades de luta, levando, em casos extremos, à morte. Objetivos Investigar o estado da hidratação antes do treino e as alterações no balanço hídrico corporal durante dois treinamentos de taekwondo. Métodos Foram avaliados 18 atletas universitários do sexo masculino (22,6 ± 3,37 anos). O desenho do estudo procurou reproduzir uma condição de treinamento de taekwondo com duração de 90 minutos, dividido em três etapas: a) aquecimento (20 min.), b) poomsae (30 min.) e c) treino técnico (40 min.). Durante o treino, adotou-se o consumo de água ad libitum. Para avaliar o estado de hidratação, considerou-se a massa corporal (MC), a quantidade de líquido consumido e o volume de urina produzido, o que permitiu estabelecer a perda hídrica absoluta e relativa em kg e porcentagem, além da taxa de sudorese. Foi considerada ainda a gravidade específica da urina (GEU), bem como sua coloração (COL-U), além da sensação subjetiva de sede (SSede) antes e depois do treino. Os resultados antes e depois do treino foram comparados de forma isolada em cada sessão, assim como entre as sessões. Resultados Houve diferença significativa (P < 0,05) da MC pré-treinamento entre os dois dias de treino. Houve redução significativa (P < 0,05) da MC final em ambos os dias de experimento. A maior parte dos avaliados apresentou desidratação relativa inferior a 2%. Registrou-se diferença significativa (P < 0,05) antes e depois do treino para COL-U e para SSede, com os maiores índices obtidos ao final de cada sessão. Os participantes sempre iniciaram o comparados de forma isolada em cada sessão, assim como entre as sessões. Resultados Houve diferença significativa (P < 0,05) da MC pré-treinamento entre os dois dias de treino. Houve redução significativa (P < 0,05) da MC final em ambos os dias de experimento. A maior parte dos avaliados apresentou desidratação relativa inferior a 2%. Registrou-se diferença significativa (P < 0,05) antes e depois do treino para COL-U e para SSede, com os maiores índices obtidos ao final de cada sessão. Os participantes sempre iniciaram o treinamento em leve estado de desidratação (GEU > 1.020 g.ml-1). Conclusões Os atletas tendem a iniciar os treinamentos em estado de desidratação, que se amplia durante o treino. O consumo de líquidos ad libitum não foi suficiente para equilibrar a perda hídrica. As alterações hídricas entre as sessões foram semelhantes. Nível de Evidência II; Estudos terapêuticos- Investigação dos resultados do tratamento.

RESUMEN Introducción La deshidratación ha sido descrita como uno de los principales factores de reducción del desempeño en actividades de lucha, llevando, en casos extremos, a la muerte. Objetivos Investigar el estado de la hidratación antes del entrenamiento y las alteraciones en el balance hídrico corporal durante dos entrenamientos de taekwondo. Métodos Se evaluaron 18 atletas universitarios del sexo masculino (22,6 ± 3,37 años). El diseño del estudio intentó reproducir una condición de entrenamiento de taekwondo con duración de 90 minutos, dividido en tres etapas: a) calentamiento (20 min); b) poomsae (30 min); y c) entrenamiento técnico (40 min). Durante el entrenamiento, se adoptó el consumo de agua ad libitum. Para evaluar el estado de hidratación, se consideró la masa corporal (MC), la cantidad de líquido consumido y el volumen de orina producido, lo que permitió establecer la pérdida hídrica absoluta y relativa en kg y porcentaje, además de la tasa de sudoración. Fue considerada además la gravedad específica de la orina (GEO), así como su coloración (COL-O), además de la sensación subjetiva de sed (SSed), antes y después del entrenamiento. Los resultados antes y después del entrenamiento fueron comparados de forma aislada en cada sesión, así como entre las sesiones. Resultados Hubo diferencia significativa (P<0,05) de la MC preentrenamiento entre los dos días de entrenamiento. Hubo reducción significativa (P<0,05) de la MC final en ambos días de experimento. La mayor parte de los evaluados presentó deshidratación relativa inferior a 2%. Se registró diferencia significativa (P<0,05) antes y después del entrenamiento para COL-O y para SSed, con los mayores índices obtenidos al final de cada sesión. Los participantes siempre iniciaron el entrenamiento en leve estado de deshidratación (GEO > 1.020 g.ml-1). Conclusiones Los atletas tienden a iniciar los entrenamientos en estado de deshidratación, que se amplía durante el entrenamiento. El consumo de líquidos ad libitum no fue suficiente para equilibrar la pérdida hídrica. Las alteraciones hídricas entre las sesiones fueron semejantes. Nivel de Evidencia II; Estudios terapéuticos - Investigación de los resultados del tratamiento.

Metabolic and volume status evaluation of hemodialysis patients with and without residual renal function in the long interdialytic interval / Avaliação metabólica e volêmica no maior intervalo interdialítico de pacientes em hemodiálise com e sem função renal residual

Abstract Introduction: It is unclear whether residual renal function (RRF) in dialysis patients can attenuate the metabolic impact of the long 68-hour interdialytic interval, in which water, acid, and electrolyte accumulation occurs. Objective: to evaluate serum electrolyte levels, water balance, and acid-base status in dialytic patients with and without RRF over the long interdialytic interval (LII). Methodology: this was a single-center, cross-sectional, and analytical study that compared patients with and without RRF, defined by diuresis above 200 mL in 24 hours. Patients were weighed and serum samples were collected for biochemical and gasometric analysis at the beginning and at the end of the LII. Results: 27 and 24 patients with and without RRF were evaluated, respectively. Patients without RRF had a higher increase in serum potassium during the LII (2.67 x 1.14 mEq/L, p < 0.001), reaching higher values at the end of the study (6.8 x 5.72 mEq/L, p < 0.001) and lower pH value at the beginning of the interval (7.40 x 7.43, p = 0.018). More patients with serum bicarbonate < 18 mEq/L (50 x 14.8%, p = 0.007) and mixed acid-base disorder (57.7 x 29.2%, p = 0.042), as well as greater interdialytic weight gain (14.67 x 8.87 mL/kg/h, p < 0.001) and lower natremia (137 x 139 mEq/L, p = 0.02) at the end of the interval. Calcemia and phosphatemia were not different between the groups. Conclusion: Patients with RRF had better control of serum potassium, sodium, acid-base status, and volemia throughout the LII.

Resumo Introdução: Não se sabe ao certo se a função renal residual (FRR) de pacientes dialíticos pode atenuar o impacto metabólico do maior intervalo interdialítico (MII) de 68 horas, no qual ocorre acúmulo de volume, ácidos e eletrólitos. Objetivo: Avaliar os níveis séricos de eletrólitos, balanço hídrico e status ácido-básico de pacientes dialíticos com e sem FRR ao longo do MII. Metodologia: Tratou-se de estudo unicêntrico, transversal e analítico, que comparou pacientes com e sem FRR, definida como diurese acima de 200 mL em 24 horas. Para tal, os pacientes foram pesados e submetidos à coleta de amostras séricas para análise bioquímica e gasométrica no início e fim do MII. Resultados: Foram avaliados 27 e 24 pacientes com e sem FRR, respectivamente. Pacientes sem FRR apresentaram maior aumento de potássio sérico durante o MII (2,67 x 1,14 mEq/L, p < 0,001) atingindo valores mais elevados no fim (6,8 x 5,72 mEq/L, p < 0,001); menor valor de pH no início do intervalo (7,40 x 7,43, p = 0,018), maior proporção de pacientes com bicarbonato sérico < 18 mEq/L (50 x 14,8 %, p = 0,007) e distúrbio ácido-básico misto (70,8 x 42,3 %, p = 0,042), além de maior ganho de peso interdialítico (14,67 x 8,87 mL/kg/h, p < 0,001) e menor natremia (137 x 139 mEq/L, p = 0,02) no fim do intervalo. A calcemia e fosfatemia não foram diferentes entre os grupos. Conclusão: Pacientes com FRR apresentaram melhor controle dos níveis séricos de potássio, sódio, status ácido-básico e da volemia ao longo do MII.

Fluid and hemodynamic management in hemodialysis patients: challenges and opportunities / Manejo hídrico e hemodinâmico em pacientes em hemodiálise: desafios e oportunidades

Abstract Fluid volume and hemodynamic management in hemodialysis patients is an essential component of dialysis adequacy. Restoring salt and water homeostasis in hemodialysis patients has been a permanent quest by nephrologists summarized by the 'dry weight' probing approach. Although this clinical approach has been associated with benefits on cardiovascular outcome, it is now challenged by recent studies showing that intensity or aggressiveness to remove fluid during intermittent dialysis is associated with cardiovascular stress and potential organ damage. A more precise approach is required to improve cardiovascular outcome in this high-risk population. Fluid status assessment and monitoring rely on four components: clinical assessment, non-invasive instrumental tools (e.g., US, bioimpedance, blood volume monitoring), cardiac biomarkers (e.g. natriuretic peptides), and algorithm and sodium modeling to estimate mass transfer. Optimal management of fluid and sodium imbalance in dialysis patients consist in adjusting salt and fluid removal by dialysis (ultrafiltration, dialysate sodium) and by restricting salt intake and fluid gain between dialysis sessions. Modern technology using biosensors and feedback control tools embarked on dialysis machine, with sophisticated analytics will provide direct handling of sodium and water in a more precise and personalized way. It is envisaged in the near future that these tools will support physician decision making with high potential of improving cardiovascular outcome.

Resumo O volume de fluidos e o controle hemodinâmico em pacientes em hemodiálise é um componente essencial da adequação da diálise. A restauração da homeostase do sal e da água em pacientes em hemodiálise tem sido uma busca constante por parte dos nefrologistas, no que condiz à abordagem do "peso seco. Embora essa abordagem clínica tenha sido associada a benefícios no desfecho cardiovascular, recentemente tem sido questionada por estudos que mostram que a intensidade ou agressividade para remover fluidos durante a diálise intermitente está associada a estresse cardiovascular e dano potencial a órgãos.para remover fluidos durante a diálise intermitente está associada a estresse cardiovascular e dano potencial a órgãos. Uma abordagem mais precisa é necessária para melhorar o desfecho cardiovascular nessa população de alto risco. A avaliação e monitorização do estado hídrico baseiam-se em quatro componentes: avaliação clínica, ferramentas instrumentais não invasivas (por exemplo, US, bioimpedância, monitorização do volume sanguíneo), biomarcadores cardíacos (e.g. peptídeos natriuréticos), algoritmos e modelagem de sódio para estimar a transferência de massa. O manejo otimizado do desequilíbrio hídrico e de sódio em pacientes dialíticos consiste em ajustar a remoção de sal e líquido por diálise (ultrafiltração, dialisato de sódio), e restringir a ingestão de sal e o ganho de líquido entre as sessões de diálise. Tecnologia moderna que utiliza biosensores e ferramentas de controle de feedback, hoje parte da máquina de diálise, com análises sofisticadas, proporcionam o manejo direto sobre o sódio e a água de uma maneira mais precisa e personalizada. Prevê-se no futuro próximo que essas ferramentas poderão auxiliar na tomada de decisão do médico, com alto potencial para melhorar o resultado cardiovascular.

Hyponatremia in elderly patients with fragility fractures of the proximal femur: a cross-sectional study / Hiponatremia em pacientes idosos com fratura proximal de fêmur por fragilidade: um estudo transversal

ABSTRACT Introduction: Proximal femur fractures affect the mortality and morbidity of elderly individuals. Recent studies have shown an association between fragility fractures and hyponatremia, a common fluid and electrolyte balance disorder. Objectives: This study aimed to investigate the occurrence of hyponatremia in patients with fragility fractures of the proximal femur. Methods: The authors looked into the data from the medical records of patients admitted to the emergency unit of the Real Hospital Português for fragility fractures of the proximal femur from 2014 to 2017. The study included patients with serum sodium levels recorded in their charts. Results: Fourteen of 69 (20.3%) patients with proximal femur fractures had hyponatremia. The main factors linked to hyponatremia were lung disease, and prescription of amiodarone and/or antidepressants. Conclusion: In elderly individuals, fragility fractures of the proximal femur may correlate with hyponatremia, particularly among patients on amiodarone or antidepressants.

RESUMO Introdução: Fratura de fêmur proximal tem impacto na mortalidade e morbidade de idosos. Estudos recentes vêm demonstrando associação entre fratura por fragilidade e hiponatremia, um distúrbio hidroeletrolítico comum na prática médica. Objetivos: Investigar a ocorrência de hiponatremia em pacientes com fratura proximal de fêmur por fragilidade. Metodologia: Foram coletados dados a partir de prontuários de pacientes admitidos na emergência do Real Hospital Português devido à fratura proximal de fêmur por fragilidade, entre 2014 e 2017, e aqueles com natremia disponível no prontuário eletrônico foram incluídos no estudo. Resultado: Dentre os 69 pacientes com fratura de fêmur proximal, houve uma ocorrência de 14 pacientes com hiponatremia, o que corresponde a 20,3%. Os principais fatores associados à hiponatremia no estudo foram doença pulmonar, uso de amiodarona e antidepressivos. Conclusão: Em idosos, a fratura de fêmur proximal por fragilidade pode estar correlacionada com hiponatremia, principalmente quando estão sob uso de amiodarona ou antidepressivos.

Fluid balance in pediatric patients in prone position: a pragmatic study

SUMMARY OBJECTIVE: To verify the association between prone position, increased diuresis, and decreased cumulative fluid balance in critically ill pediatric patients who underwent mechanical ventilation (MV) for pulmonary causes and describe adverse events related to the use of the position. METHODS: This is a retrospective observational study. Patients aged between 1 month and 12 years who underwent MV for pulmonary causes, between January 2013 and December 2015, were selected and divided between those who were put on prone position (PG) and those who were not (CG) during the hospitalization at the Pediatric Intensive Care Unit (PICU). Data were analyzed longitudinally from D1 to D4. RESULTS: A total of 77 patients (PG = 37 and CG = 40) were analyzed. The general characteristics of both groups were similar. In the comparison between the groups, there was no increase in diuresis or decrease in cumulative fluid balance in the prone group. In the longitudinal analysis of D1 to D4, we saw that the PG presented higher diuresis (p = 0.034) and a lower cumulative fluid balance (p = 0.001) in D2. Regarding the use of diuretics, there was greater use of furosemide (P <0.001) and spironolactone (P = 0.04) in the PG. There was no increase in adverse events during the use of the prone position. CONCLUSION: The prone position was not associated with increased diuresis or decreased cumulative fluid balance in critically ill pediatric patients who underwent to MV for pulmonary causes.

RESUMO OBJETIVO: Verificar a associação entre posição prona, aumento da diurese e diminuição do balanço hídrico em pacientes pediátricos criticamente enfermos e submetidos à ventilação mecânica (VM) por causa pulmonar, além de descrever eventuais intercorrências relacionadas à aplicação dessa posição. MÉTODOS: Estudo observacional retrospectivo. Pacientes submetidos à VM por causa pulmonar, com idade entre 1 mês e 12 anos no período entre janeiro de 2013 e dezembro de 2015, foram selecionados e divididos entre os que receberam posição prona (GP) e os que não receberam (GC) durante a internação na Unidade de Terapia Intensiva Pediátrica (Utip). Os dados foram analisados longitudinalmente de D1 a D4. RESULTADOS: Foram analisados77 pacientes (GP=37 e GC=40). Em termos de características gerais, os grupos foram semelhantes entre si. Na comparação entre os grupos, não houve aumento da diurese ou diminuição do balanço hídrico cumulativo no grupo prona. Na análise longitudinal de D1 a D4, evidenciou-se que o GP apresentou maior diurese (p=0,034) e menor balanço hídrico cumulativo (p = 0,001) no D2. Com relação ao uso de diuréticos, houve maior uso de furosemida (P<0,001) e de espironolactona (P=0,04) no GP. Não houve aumento de eventos adversos durante a utilização da posição prona. CONCLUSÃO: A posição prona não demonstrou associação com aumento da diurese ou diminuição de balanço hídrico cumulativo em pacientes críticos pediátricos submetidos à VM por causa pulmonar.

Análisis función ventricular derecha, función renal y fluidos tras resucitación en pacientes con ventilación mecánica / Right ventricular, renal function, and fluids balance analysis after resuscitation in patients on mechanical ventilation

INTRODUCTION: Hemodynamic optimization is a main goal in the management of critically ill patients. Right ventricular function, renal failure and fluid balance are part of this process. Our goal is to analysis those, after the initial resuscitation. MATERIAL AND METHODS: A prospective, observational study was performed with all the patients admitted to a Medical Service of Intensive Care of a Tertiary, University Hospital. All patients analyzed required mechanical ventilation as a support for their underling pathology. All consecutive patients admitted to the unit under mechanical ventilation were collected, in the absence of shock, with the expectation of remaining under mechanical ventilation for at least 24 more hours after data collection. The incidence of right ventricular failure according to the defined parameters, renal failure, and fluid balance were described. We had described its association with mechanical ventilation and mortality. RESULTS: A total of 30 patients were selected. Right ventricular failure was observed in 16.6% of patients (5/30). There was no statistically significant association with the need of tracheotomy, renal failure or mortality. It was not associated with longer average stay, days of mechanical ventilation or higher severity scores. 40% of the patients presented acute renal failure. Renal failure was not associated statistically significant with the need of tracheotomy or failure in scheduled extubation, however, it was associated with higher mortality. Patients requiring mechanical ventilation with normal creatinine values ​​after initial resuscitation, had a mortality rate of 28.5% in comparison to patients who had altered values in which the mortality rate was 77.7%, (p < 0.018). Regarding the post-resuscitation net fluid balance, no statistically significant differences were found in the comparison of means between survivors and non survivors, with renal failure or right ventricular failure. No even was it associated with higher mortality. CONCLUSIONS: Right ventricular failure, despite not being associated with mortality, days of mechanical ventilation or failure in extubation in a statistically significant way, presents an incidence of 16.6% in patients connected to mechanical ventilation admitted to a polyvalent icu. Acute renal failure is associated in a statistically significant way with mortality in our sample. We had not found association between fluid overload and renal failure in our sample.

INTRODUCCIÓN: La optimización hemodinámica es piedra angular en el manejo del enfermo crítico. La función ventricular derecha, el fallo renal y el balance hídrico son parte de este proceso. Nuestro objetivo es su análisis tras la resucitación inicial. MATERIAL Y MÉTODOS: Se realiza un estudio prospectivo, observacional, con todos los enfermos que ingresan en un Servicio médico de Medicina Intensiva de un Hospital Terciario y Universitario. Todos los enfermos analizados precisan ventilación mecánica como soporte de su patología. Se recogen todos los enfermos consecutivos ingresados en la unidad bajo ventilación mecánica, en ausencia de shock, con previsión de permanecer bajo ventilación mecánica al menos 24 horas más tras la recogida de datos. Se describe la incidencia de fallo ventricular derecho según los parámetros definidos, fallo renal, balance. Describiremos también su asociación con ventilación mecánica, mortalidad. RESULTADOS: Se seleccionaron un total de 30 pacientes. Se objetivó fallo ventricular derecho en el 16,6% de los pacientes (5/30). No se asoció de forma estadísticamente significativa a la necesidad de traqueotomía, fallo renal o mortalidad. Tampoco se asoció a mayor estancia media, días de ventilación mecánica o índices de gravedad mayores. El 40% de los pacientes presentaron fallo renal agudo. El fallo renal no se asocia de forma estadísticamente significativa con la necesidad de traqueotomía ni fracaso en la extubación, sin embargo, se asocia a mayor mortalidad. Los pacientes que precisan ventilación mecánica y presentan valores de creatinina normales tras resucitación inicial, cuentan con una tasa de mortalidad del 28,5% en comparación con aquellos pacientes que presentan cifras alteradas en las cuales la tasa de mortalidad es del 77,7%, (p < 0,018). Con respecto al balance hídrico neto post resucitación, no se encontraron diferencias estadísticamente significativas en la comparación de medias de los supervivientes, con fallo renal o fallo en ventrículo derecho. Tampoco se asoció a mayor mortalidad. CONCLUSIONES: El fallo ventricular derecho, pese a no asociarse a la mortalidad, días de ventilación mecánica o fallo en la extubación de forma estadísticamente significativa, presenta una incidencia del 16,6% en los enfermos conectados a ventilación mecánica ingresados en una uci polivalente. El fallo renal agudo sí se asocia de forma estadísticamente significativa a la mortalidad en nuestra muestra. No hemos encontrado asociación entre sobrecarga hídrica y fallo renal en nuestro estudio.

Equilíbrio ácido-base e hidroeletrolítico em equinos submetidos à simulação de enduro FEI / Acid-base and hidroelectrolytic balance in horses undergoing FEI endurance ride simulation

Enduro é uma modalidade equestre que demanda alta exigência dos sistemas orgânicos para que seja mantida a homeostasia do organismo. Objetivou-se avaliar o equilíbrio ácido-base e hidroeletrolítico durante uma prova de enduro realizada por equinos FEI*. Nove equinos foram submetidos a três meses de treinamento e, ao final, realizou-se prova similar às competições oficiais de enduro equestre, com trajeto de 80km, dividido em quatro etapas (anéis). Avaliações clínicas e coletas de amostras sanguíneas para análise da concentração de lactato e variáveis hemogasométricas foram realizadas no início da prova, imediatamente após a chegada de cada anel e, após 15 e 30 minutos, uma, quatro, seis e 12 horas do término da prova. Apenas cinco animais concluíram a prova e, para análise estatística, foram utilizados somente os dados destes animais. Houve predomínio do metabolismo aeróbio durante a prova e os animais mostraram bom índice de recuperação. Os eletrólitos cloreto, sódio, potássio e cálcio tiveram sua concentração diminuída, enquanto o bicarbonato aumentou no transcorrer do exercício. Os valores de pH aumentaram em decorrência do desenvolvimento de alcalose mista, caracterizada por alcalose metabólica hipoclorêmica e alcalose respiratória. O bom desempenho dos animais foi atribuído à suficiente adaptação metabólica induzida pelo treinamento.(AU)

Endurance is an equestrian modality that demands high requirement of organic systems in order to maintain organism's homeostasis. This study aimed to evaluate hydroelectrolyte and acid-base balance during an endurance test performed by FEI* horses. Nine horses were subjected to three months of training and, at the end, performed a test similar to the official competitions of equestrian endurance, with 80 km of distance, divided into four stages. Clinical and blood samples were taken for analysis of lactate concentration and blood gas parameters before the start of the test, immediately after the arrival of each phase and, after 15, 30 minutes, 1, 4, 6 and 12 hours after the end of the race. Only five animals completed the race and the data from these animals were used for statistical analysis. There was predominance of aerobic metabolism and the horses showed a good recovery rate. The electrolytes chloride, sodium, potassium and calcium had their concentration decreased while bicarbonate increased with the course of the exercise. There was an increase in pH due to the development of mixed alkalosis, characterized by hypochloremic metabolic alkalosis and respiratory alkalosis. Good performance of the animals was attributed to sufficient metabolic adaptation induced by training.(AU)

Balance de líquidos y lesión renal aguda en el choque séptico / Fluid balance and acute kidney injury in septic shock

Resumen: Introducción: En el paciente con choque séptico, la administración excesiva de líquidos puede incrementar la morbilidad y mortalidad. El objetivo de este estudio fue evaluar la asociación entre el balance de líquidos, la lesión renal aguda y la mortalidad en pacientes con choque séptico. Métodos: Se realizó un estudio de casos y controles en una unidad de terapia intensiva pediátrica. Se comparó el balance de líquidos en las primeras 72 h y la presencia de lesión renal aguda en pacientes con diagnóstico de choque séptico que fallecieron contra pacientes que sobrevivieron a la misma patología. Se realizó un análisis univariado y multivariado. Resultados: Se incluyeron 45 casos y 45 controles en el análisis. La mortalidad se asoció con riesgo pediátrico de mortalidad (PRISM) ≥ 26 puntos (RM 7.5, IC 95% 2.8-18.7; p = 0.000), disfunción orgánica logística pediátrica (PELOD) ≥ 24 puntos (RM 11.0, IC 95% 4.1-29.4; p = 0.000), creatinina ≥ 0.65 mg/dl (RM 5.6, IC 95% 2.2-13.9; p = 0.000), lactato ≥ 2.5 mmol/l (RM 2.5, IC 95% 1.1-5.9; p = 0.033), SvO2 < 60% (RM 4.6, IC 95% 4.5-4.5; p = 0.001), balance positivo > 9% en 72 h (RM 4.3, IC 95% 1.6-11.7; p = 0.003), lesión renal aguda (RM 5.7, IC 95% 2.2-15.1; p = 0.000). En el modelo multivariado, PRISM ≥ 26 y PELOD ≥ 24 puntos permanecieron significativas. Conclusiones: En los pacientes que fallecieron por choque séptico, el modelo multivariado mostró una asociación con PRISM ≥26 y PELOD ≥24 y una tendencia hacia la asociación con SvO2 <60% y balance de líquidos positivo >9%.

Abstract: Background: In patients with septic shock, excessive fluid administration can lead to increased morbidity and mortality. The aim of this study was to evaluate the association between fluid balance, acute kidney injury and mortality in patients with septic shock. Methods: A study of cases and controls was conducted in a Pediatric Intensive Care Unit. The fluid balance in the first 72 h and the presence of acute kidney injury was compared in patients diagnosed with septic shock who died against patients who survived the same condition. Univariate and multivariate analyses were performed. Results: Forty-five cases and forty-five controls were included in the analysis. Mortality was associated with Pediatric Risk of Mortality (PRISM III) ≥ 26 points (OR 7.5, 95% CI 2.8-18.7; p = 0.000), Pediatric Logistic Organ Dysfunction (PELOD) ≥ 24 points (OR 11.0, 95% CI 4.1-29.4; p = 0.000), creatinine ≥ 0.65 mg/dl (OR 5.6, 95% CI 2.2-13.9; p = 0.000), lactate ≥ 2.5 mmol/l (OR 2.5, 95% CI 1.1-5.9; p = 0.033), SvO2 < 60% (OR 4.6, 95% CI 4.5-4.5; p = 0.001), positive balance > 9% in 72 h (OR 4.3, 95% CI 1.6-11.7; p = 0.003), acute kidney injury (OR 5.7, 95% CI: 2.2-15.1; p = 0.000). In the multivariate model, the values of PRISM ≥26 and PELOD ≥24 points were significant. Conclusions: In patients who died due to septic shock, the multivariate model showed an association with PRISM ≥26 and PELOD ≥24 and a trend toward association with SvO2 <60% and positive balance of liquids > 9%.

Correlation between predialysis systolic blood pressure and predialysis hydration status in hemodialysis patients / Correlación entre la presión arterial sistólica prediálisis y el estado de hidratación prediálisis en pacientes de hemodiálisis

One of the goals of hemodialysis is to maintain normal hydration status in ESRD patients.Pre hemodialysis systolic blood pressure is usually used as a clinical parameter of hydration status and to set ultrafiltration rate before Hd. It is unclear how much pre-Hd SBP correlated with hydration status. The aimwas to determine correlation between pre-Hd SBP and hydration status before Hd. An observational correlation study was performed in two dialysis centers in Santiago, Chile, from January-June, 2011. Adult patients inHd for at least three months, who gave their informed consent were included. Patients with pacemaker,amputee, hospitalized and metallic prostheses were excluded. Total-body water and over hydrated were assessed with bioimpedance spectroscopy before the first and third dialysis session of the week. Pre-Hd SBP,pre-Hd body weight, pre-Hd TBW and pre-Hd OH, were analyzed using Pearson correlation and linear regressionmodel. 96 measurements were assessed, 52 % were male with median age 59.5 years. The correlationbetween pre-Hd SBP and pre-Hd overhydration was r=0.33, and total body water r=0.15, with a predictedvalue, R2=0.10 and R2 =0.14 respectively. Pre-Hd SBP had low correlation with pre-Hd hydration status and by itself, is not a reliable parameter to set ultrafiltration rate before Hd. Nevertheless Pre-Hd body weight predicted in 70 % the pre-Hd TBW.

Uno de los objetivos de la hemodiálisis es mantener la hidratación normal en pacientes ESRD. La presión arterial sistólica pre hemodiálisis, es usualmente utilizada como parámetro clínico del estado de hidratación y para fijar la velocidad de ultrafiltración antes de la hemodialisis. No está claro cuanto se correlacionan la presión arterial sistólica prehemodialysis con el estado de hidratación. El objetivo fue determinar la correlación entre la PAS prehemodiálisis y el estado de hidratación antes de Hd. Se realizó un estudio de correlación observacional en dos centros de diálisis de Santiago de Chile, de Enero a Junio de 2011. Se incluyeron pacientes adultos en HD durante al me-nos tres meses que dieran su consentimiento informado. Se excluyeron los pacientes con marcapasos, amputados, hospitalizados y pró-tesis metálicas. El agua corporal total y el exceso de hidratación se evaluaron con espectroscopia 1030 de bioimpedancia antes de la primera y tercera sesión de diálisis de la semana. Pre-Hd PAS, pre-Hd peso corporal, pre-Hd ACT y pre-Hd OH, se analizaron utilizando el modelo de correlación y regresión lineal de Pearson. Se evaluaron 96 mediciones, 52% eran hombres con edad media 59, 5 años. La correlación entre la PAS pre-Hd y la sobrehidratación pre-Hd fue r=0, 33 y agua corporal total r=0, 15, con un valor predicho, R2= 0, 10 y R2 = 0, 14 respectivamente. Existe baja correlación entre la PAS Pre-Hd con el esta-do de hidratación pre-Hd y por lo mismo, no es un parámetro confiable para establecer la tasa de ultrafiltración antes de Hd. Sin embargo, el peso corporal Pre-Hd predijo en un 70% el agua corporal total pre-Hd.

Influence of Daily Fluid Balance prior to Continuous Renal Replacement Therapy on Outcomes in Critically Ill Patients

Positive fluid balance is a risk factor for mortality in critically ill patients, especially those requiring continuous renal replacement therapy (CRRT). However, the association between daily fluid balance and various organ impairments remains unclear. This study investigated the impacts of daily fluid balance prior to CRRT on organ dysfunction, as well as mortality in critically ill patients. We identified daily fluid balance between intensive care unit (ICU) admission and CRRT initiation. According to daily fluid balance, the time to CRRT initiation and the rate of organ failure based on the sequential organ failure assessment (SOFA) score were assessed. We recruited 100 patients who experienced CRRT for acute kidney injury. CRRT was initiated within 2 [0, 4] days. The time to CRRT initiation was shortened in proportion to daily fluid balance, even after the adjustment for the renal SOFA score at ICU admission (HR 1.14, P = 0.007). Based on the SOFA score, positive daily fluid balance was associated with respiratory, cardiovascular, nervous, and coagulation failure, independent of each initial SOFA score at ICU admission (HR 1.36, 1.26, 1.24 and 2.26, all P < 0.05). Ultimately, we found that positive fluid balance was related with an increase in the rate of 28-day mortality (HR 1.14, P = 0.012). Positive daily fluid balance may accelerate the requirement for CRRT, moreover, it can be associated with an increased risk of multiple organ failure in critically ill patients.

Influence of Daily Fluid Balance prior to Continuous Renal Replacement Therapy on Outcomes in Critically Ill Patients

Positive fluid balance is a risk factor for mortality in critically ill patients, especially those requiring continuous renal replacement therapy (CRRT). However, the association between daily fluid balance and various organ impairments remains unclear. This study investigated the impacts of daily fluid balance prior to CRRT on organ dysfunction, as well as mortality in critically ill patients. We identified daily fluid balance between intensive care unit (ICU) admission and CRRT initiation. According to daily fluid balance, the time to CRRT initiation and the rate of organ failure based on the sequential organ failure assessment (SOFA) score were assessed. We recruited 100 patients who experienced CRRT for acute kidney injury. CRRT was initiated within 2 [0, 4] days. The time to CRRT initiation was shortened in proportion to daily fluid balance, even after the adjustment for the renal SOFA score at ICU admission (HR 1.14, P = 0.007). Based on the SOFA score, positive daily fluid balance was associated with respiratory, cardiovascular, nervous, and coagulation failure, independent of each initial SOFA score at ICU admission (HR 1.36, 1.26, 1.24 and 2.26, all P < 0.05). Ultimately, we found that positive fluid balance was related with an increase in the rate of 28-day mortality (HR 1.14, P = 0.012). Positive daily fluid balance may accelerate the requirement for CRRT, moreover, it can be associated with an increased risk of multiple organ failure in critically ill patients.

Fluid distribution kinetics during cardiopulmonary bypass

OBJECTIVE: The purpose of this study was to examine the isovolumetric distribution kinetics of crystalloid fluid during cardiopulmonary bypass. METHODS: Ten patients undergoing coronary artery bypass grafting participated in this prospective observational study. The blood hemoglobin and the serum albumin and sodium concentrations were measured repeatedly during the distribution of priming solution (Ringer's acetate 1470 ml and mannitol 15% 200 ml) and initial cardioplegia. The rate of crystalloid fluid distribution was calculated based on 3-min Hb changes. The preoperative blood volume was extrapolated from the marked hemodilution occurring during the onset of cardiopulmonary bypass. Clinicaltrials.gov: NCT01115166. RESULTS: The distribution half-time of Ringer's acetate averaged 8 minutes, corresponding to a transcapillary escape rate of 0.38 ml/kg/min. The intravascular albumin mass increased by 5.4% according to mass balance calculations. The preoperative blood volume, as extrapolated from the drop in hemoglobin concentration by 32% (mean) at the beginning of cardiopulmonary bypass, was 0.6-1.2 L less than that estimated by anthropometric methods (p<0.02). The mass balance of sodium indicated a translocation from the intracellular to the extracellular fluid space in 8 of the 10 patients, with a median volume of 236 ml. CONCLUSIONS: The distribution half-time of Ringer's solution during isovolumetric cardiopulmonary bypass was 8 minutes, which is the same as for crystalloid fluid infusions in healthy subjects. The intravascular albumin mass increased. Most patients were hypovolemic prior to the start of anesthesia. Intracellular edema did not occur. .

From Escherichia coli heat-stable enterotoxin to mammalian endogenous guanylin hormones

The isolation of heat-stable enterotoxin (STa) from Escherichia coli and cholera toxin from Vibrio cholerae has increased our knowledge of specific mechanisms of action that could be used as pharmacological tools to understand the guanylyl cyclase-C and the adenylyl cyclase enzymatic systems. These discoveries have also been instrumental in increasing our understanding of the basic mechanisms that control the electrolyte and water balance in the gut, kidney, and urinary tracts under normal conditions and in disease. Herein, we review the evolution of genes of the guanylin family and STa genes from bacteria to fish and mammals. We also describe new developments and perspectives regarding these novel bacterial compounds and peptide hormones that act in electrolyte and water balance. The available data point toward new therapeutic perspectives for pathological features such as functional gastrointestinal disorders associated with constipation, colorectal cancer, cystic fibrosis, asthma, hypertension, gastrointestinal barrier function damage associated with enteropathy, enteric infection, malnutrition, satiety, food preferences, obesity, metabolic syndrome, and effects on behavior and brain disorders such as attention deficit, hyperactivity disorder, and schizophrenia.

Effects of nitric oxide on magnocellular neurons of the supraoptic nucleus involve multiple mechanisms

Physiological evidence indicates that the supraoptic nucleus (SON) is an important region for integrating information related to homeostasis of body fluids. Located bilaterally to the optic chiasm, this nucleus is composed of magnocellular neurosecretory cells (MNCs) responsible for the synthesis and release of vasopressin and oxytocin to the neurohypophysis. At the cellular level, the control of vasopressin and oxytocin release is directly linked to the firing frequency of MNCs. In general, we can say that the excitability of these cells can be controlled via two distinct mechanisms: 1) the intrinsic membrane properties of the MNCs themselves and 2) synaptic input from circumventricular organs that contain osmosensitive neurons. It has also been demonstrated that MNCs are sensitive to osmotic stimuli in the physiological range. Therefore, the study of their intrinsic membrane properties became imperative to explain the osmosensitivity of MNCs. In addition to this, the discovery that several neurotransmitters and neuropeptides can modulate their electrical activity greatly increased our knowledge about the role played by the MNCs in fluid homeostasis. In particular, nitric oxide (NO) may be an important player in fluid balance homeostasis, because it has been demonstrated that the enzyme responsible for its production has an increased activity following a hypertonic stimulation of the system. At the cellular level, NO has been shown to change the electrical excitability of MNCs. Therefore, in this review, we focus on some important points concerning nitrergic modulation of the neuroendocrine system, particularly the effects of NO on the SON.

Efeito de soluções eletrolíticas enterais com diferentes osmolaridades sobre o perfil eletrolítico e bioquímico de equinos / Horses treated with enteral electrolyte solutions with differents osmolarities

Foram comparados os efeitos de soluções eletrolíticas com diferentes osmolaridades administradas via enteral por sonda nasoesofágica de pequeno calibre, em fluxo contínuo, sobre o perfil bioquímico em equinos. Foram utilizadas seis fêmeas adultas em dois quadrados latinos 6x3 simultâneos em modelo misto. Os animais foram distribuídos em três grupos e cada grupo submetido aos seguintes tratamentos: HipoMalt - 5g de cloreto de sódio, 0,5g de cloreto de potássio, 0,2g de pidolato de magnésio, 1g de gluconato de cálcio e 10g de maltodextrina diluídos em 1.000mL de água (181mOsmol L-1), HipoDext - 5g de cloreto de sódio, 0,5g de cloreto de potássio, 0,2g de pidolato de magnésio, 1g de gluconato de cálcio e 10g de dextrose diluídos em 1.000mL de água (228mOsmol L-1) e IsoProp - 5g de cloreto de sódio, 0,5g de cloreto de potássio, 0,2g de pidolato de magnésio e 10g de propionato de cálcio diluídos em 1.000mL de água (282mOsm L-1). As soluções contendo dextrose (HipoDext) e maltodextrina (HipoMalt) foram mais eficazes em aumentar a taxa glicêmica sem ocasionar desequilíbrio eletrolítico. Já o tratamento com propionato de cálcio (IsoProp) além de aumentar o lactato plasmático não teve efeito sobre a glicemia.

We compared the effects of electrolyte solutions with different osmolarities administered through enteral route by naso-esophageal probe of small-caliber with continuos flow on the electrolytic and biochemical profile in horses. Six adult females were used in two simultaneous 6x3 Latin squares mixed model. The animals were divided into three groups and received the following treatments: HipoMalt - 5g of sodium chloride, 0.5g of potassium chloride, 0.2g of magnesium pidolate, 1g of calcium gluconate and 10g of maltodextrin diluted in 1.000mL of water (181mOsmol L-1); HipoDext - 5g of sodium chloride, 0.5g of potassium chloride, 0.2g of magnesium pidolate, 1g of calcium gluconate and 10g of dextrose diluted in 1.000mL of water (228mOsmol L-1); IsoProp - 5g of sodium chloride, 0.5g of potassium chloride, 0.2g of magnesium pidolate, 1g of calcium gluconate and 10g of calcium propionate diluted in 1.000mL of water (282mOsm L-1). The hypotonic electrolyte solutions containing dextrose (HipoDext) and maltodextrin (HipoMalt) were more effective in increase the rate glucose without causing electrolyte imbalance. Treatment with calcium propionate (IsoProp) besides increasing plasma lactate had no effect on blood glucose.

Roles of estrogen and progesterone in modulating renal nerve function in the rat kidney

The maintenance of extracellular Na+ and Cl- concentrations in mammals depends, at least in part, on renal function. It has been shown that neural and endocrine mechanisms regulate extracellular fluid volume and transport of electrolytes along nephrons. Studies of sex hormones and renal nerves suggested that sex hormones modulate renal function, although this relationship is not well understood in the kidney. To better understand the role of these hormones on the effects that renal nerves have on Na+ and Cl- reabsorption, we studied the effects of renal denervation and oophorectomy in female rats. Oophorectomized (OVX) rats received 17β-estradiol benzoate (OVE, 2.0 mg·kg-1·day-1, sc) and progesterone (OVP, 1.7 mg·kg-1·day-1, sc). We assessed Na+ and Cl- fractional excretion (FENa+ and FECl- , respectively) and renal and plasma catecholamine release concentrations. FENa+ , FECl- , water intake, urinary flow, and renal and plasma catecholamine release levels increased in OVX vs control rats. These effects were reversed by 17β-estradiol benzoate but not by progesterone. Renal denervation did not alter FENa+ , FECl- , water intake, or urinary flow values vs controls. However, the renal catecholamine release level was decreased in the OVP (236.6±36.1 ng/g) and denervated rat groups (D: 102.1±15.7; ODE: 108.7±23.2; ODP: 101.1±22.1 ng/g). Furthermore, combining OVX + D (OD: 111.9±25.4) decreased renal catecholamine release levels compared to either treatment alone. OVE normalized and OVP reduced renal catecholamine release levels, and the effects on plasma catecholamine release levels were reversed by ODE and ODP replacement in OD. These data suggest that progesterone may influence catecholamine release levels by renal innervation and that there are complex interactions among renal nerves, estrogen, and progesterone in the modulation of renal function.

Involvement of catecholaminergic medullary pathways in cardiovascular responses to acute changes in circulating volume

Water deprivation and hypernatremia are major challenges for water and sodium homeostasis. Cellular integrity requires maintenance of water and sodium concentration within narrow limits. This regulation is obtained through engagement of multiple mechanisms and neural pathways that regulate the volume and composition of the extracellular fluid. The purpose of this short review is to summarize the literature on central neural mechanisms underlying cardiovascular, hormonal and autonomic responses to circulating volume changes, and some of the findings obtained in the last 12 years by our laboratory. We review data on neural pathways that start with afferents in the carotid body that project to medullary relays in the nucleus tractus solitarii and caudal ventrolateral medulla, which in turn project to the median preoptic nucleus in the forebrain. We also review data suggesting that noradrenergic A1 cells in the caudal ventrolateral medulla represent an essential link in neural pathways controlling extracellular fluid volume and renal sodium excretion. Finally, recent data from our laboratory suggest that these structures may also be involved in the beneficial effects of intravenous infusion of hypertonic saline on recovery from hemorrhagic shock.

Time motion analysis of football (soccer) referees during official matches in relation to the type of fluid consumed

The aim of the present study was to determine the effect of volume and composition of fluid replacement on the physical performance of male football referees. Ten referees were evaluated during three official matches. In one match the participants were asked to consume mineral water ad libitum, and in the others they consumed a pre-determined volume of mineral water or a carbohydrate electrolyte solution (6.4 percent carbohydrate and 22 mM Na+) equivalent to 1 percent of their baseline body mass (half before the match and half during the interval). Total water loss, sweat rate and match physiological performance were measured. When rehydrated ad libitum (pre-match and at half time) participants lost 1.97 ± 0.18 percent of their pre-match body mass (2.14 ± 0.19 L). This parameter was significantly reduced when they consumed a pre-determined volume of fluid. Sweat rate was significantly reduced when the referees ingested a pre-determined volume of a carbohydrate electrolyte solution, 0.72 ± 0.12 vs 1.16 ± 0.11 L/h ad libitum. The high percentage (74.1 percent) of movements at low speed (walking, jogging) observed when they ingested fluid ad libitum was significantly reduced to 71 percent with mineral water and to 69.9 percent with carbohydrate solution. An increase in percent movement expended in backward running was observed when they consumed a pre-determined volume of carbohydrate solution, 7.7 ± 0.5 vs 5.5 ± 0.5 percent ad libitum. The improved hydration status achieved with the carbohydrate electrolyte solution reduced the length of time spent in activities at low-speed movements and increased the time spent in activities demanding high-energy expenditure.

Biorregulador e pré-condicionamento osmótico na germinação de sementes e no crescimento inicial da muda de carobinha (Jacaranda decurrens subsp. symmetrifoliolata Farias & Proença) - Bignoniaceae / Bioregulator and priming on seed germination and initial growth of "carobinha" (Jacaranda decurrens subsp. symmetrifoliolata Farias & Proença - Bignoniaceae) seedlings

O objetivo deste trabalho foi avaliar o efeito de tratamentos pré-germinativos na emergência das plantas e no crescimento inicial das mudas de Jacaranda decurrens subsp. symmetrifoliolata Farias & Proença. Foram realizados dois experimentos. No primeiro, as sementes, separadas em claras e escuras, foram submetidas aos tratamentos pré-germinativos: 1) KNO3 (20000 mg L-1); 2) ácido giberélico (GA3) 50 mg L-1, 3) GA3 100 mg L-1 4) GA3 200 mg L-1; 5) Stimulate 5 mL 0,5 kg-1 de sementes; 6) Stimulate 10 mL 0,5 kg-1 de sementes; 7) água 24 horas; 8) testemunha. A semeadura foi realizada em bandejas de células preenchidas com substrato terra + substrato comercial. Os cinco melhores tratamentos foram selecionados para avaliação do crescimento da muda. As plantas com 120 dias de idade provenientes dos seguintes tratamentos: 3) GA 100 mg L-1 4) GA 200 mg L-1; 5) Stimulate 5 mL 0,5 Kg-1 de sementes 6) Stimulate 10 mL 0,5 Kg-1 de sementes e 8) Testemunha, foram transplantadas para embalagens de plástico de 3 Kg com substrato terra + areia + cama-de-frango (1:1:1 - v:v), mantidas em sombreamento de 50 por cento e avaliadas aos 70, 130, 170 e 210 dias após o transplante. Em geral, as sementes claras apresentaram maior germinabilidade e índice de velocidade de germinação (IVG) em relação às sementes escuras. Entretanto, as plantas provenientes dessas sementes apresentaram menor crescimento do que as plantas provenientes das sementes escuras. No segundo experimento as sementes foram pré-embebidas em solução de: 1) PEG 6000 (-1,0 MPa); 2) PEG 6000 (-1,0 MPa) + KNO3 (20000 mg L-1) (-1,0 MPa); 3) KNO3 (20000 mg L-1) (-1,0 MPa); 4) Água e 5) água deionizada, e incubadas em BOD a 10ºC e 20ºC durante 0 (controle), 6, 12 e 24 horas. Após esses períodos elas foram secas em ambiente de laboratório até atingirem a massa apresentada antes do condicionamento e, posteriormente, incubadas em BOD a 20-30ºC com 8 h escuro e 12 h de luz. Os tratamentos pré-germinativos não interferiram na vitalidade e no vigor das sementes osmocondicionadas por até 12 horas. Não houve diferença entre as temperaturas de 10 e 20ºC para germinabilidade (60 por cento) e IVG, porém a temperatura de 10ºC originou plântulas com maior massa fresca (95,7 mg) e comprimento médio de raiz (3,2 cm) e de parte aérea (2,6 cm). O osmocondicionamento por 24 horas causou redução na qualidade das sementes e vigor das plântulas.

The aim of this work was to evaluate the effect of pregerminative treatments on the emergence and initial growth of Jacaranda decurrens subsp. symmetrifoliolata Farias & Proença seedlings. Two experiments were carried out. In the first experiment, seeds were separated into light and dark seeds and were subjected to the following pregerminative treatments: 1) KNO3 (20000 mg L-1); 2) Gibberellic acid (GA3) 50 mg L-1, 3) GA3 100 mg L-1 4) GA3 200 mg L-1; 5) Stimulate 5 mL 0.5 kg-1 seeds; 6) Stimulate 10 mL 0.5 kg-1 seeds; 7) Water 24h; and 8) Control. The sowing was performed on polystyrene trays filled with land + commercial substrate. The five best treatments were selected to evaluate seedling growth. Plants aged 120 days from treatments 3, 4, 5, 6 and 8 were transplanted to plastic bags (3kg) filled with land + sand + poultry manure (1:1:1 - v:v), kept under 50 percent shading and evaluated at 70, 130, 170 and 210 days after transplanting. In general, light seeds had higher germinability and germination speed index (GSI) than the dark ones. However, the plants obtained from these seeds had lower growth than plants from dark seeds. In the second experiment, seeds were primed in the solutions: 1) PEG 6000 (-1.0 MPa); 2) PEG 6000 (-1.0 MPa) + KNO3 (20000 mg L-1) (-1.0 MPa); 3) KNO3 (20000 mg L-1) (-1.0 MPa); 4) Water; and 5) Deionized water, and incubated in a BOD chamber at 10 and 20ºC for 0 (control), 6, 12 and 24h. Then, seeds were dried at room temperature until reaching the matter presented before priming and incubated in a BOD chamber at 20-30ºC with 8h dark - 12h light. The pregerminative treatments did not interfere with the vitality and vigor of seeds primed for up to 12h. There was no difference between 10 and 20ºC for germinability (60 percent) and GSI. However, the temperature of 10ºC led seedlings to present higher fresh matter (95.7 mg) and mean root (3.2 cm) and shoot (2.6 cm) length. Priming for 24h decreased seed quality and seedling vigor.

Water-balance response of Rhinella arenarum (Hensel, 1867) tadpoles to graduated increase in environmental osmolarity / Resposta de Rhinella arenarum larvae a meio electrolítico e não electrolítico com aumento escalonado da osmolaridade

The water balance and the upper limit of osmotic tolerance of premetamorphic Rhinella arenarum larvae (Gosner's stage 26) was evaluated after semistatic incubation in electrolyte (NaCl) and non-electrolyte (mannitol) media following a protocol of progressively increased osmotic pressure. Wet and dry weights were measured to calculate the water content as a derived variable indicative of the hydric balance. Statistical analysis was performed using univariate and integrated multivariate analysis. Tadpoles survived in electrolyte and non-electrolyte solutions up to 200 mOsm. The discriminant function was the best tool to describe the responses of the animals to external environmental stress under experimental conditions. The results were compared with those obtained in previous studies using a protocol of acute exposure to the same media used in this study. It was concluded that a) multivariate analysis is an appropriate approach to describe the responses of tadpoles to changes in the environmental physicochemical parameters, and b) progressive and acute acclimation to the experimental solutions induced similar responses.

Avaliou-se o balanço hídrico e o limite superior de tolerância osmótica em larvas pré-metamórficas do Rhinella arenarum (etapa 26 de Gosner) sob condições de incubação semiestáticas, num meio eletrolítico (NaCl) e não eletrolítico (manitol), seguindo um protocolo de aumento progressivo da pressão osmótica do meio. A quantificação das respostas se efetuou por meio da medição dos valores de peso úmido e seco e do cálculo, a partir destes, do conteúdo de água, como variável derivada indicativa do equilíbrio hídrico. A análise estatística foi realizada usando análise univariada e multivariada. As larvas conseguiram sobreviver em soluções eletrolíticas e não eletrolíticas até 200 mOsm. A função discriminante foi a melhor ferramenta para descrever as respostas dos animais ao estresse osmótico ambiental. Os resultados foram comparados com os obtidos em estudos anteriores, usando um protocolo de exposição aguda aos mesmos meios de incubação usados neste estudo. Concluiu-se: a) a análise multivariada é a aproximação adequada para descrever as respostas das larvas às mudanças nos parâmetros físico-químicos do seu meio; e b) tanto a aclimatação progressiva, como as exposições agudas às soluções experimentais induziram as respostas semelhantes.