Volume dynamics and volume management in intensive care unit patients / 中华危重病急救医学

Volume dynamics is a two-compartment dynamical model using hemoglobin (Hb) derived plasma diluted level as input data and urine output as input variable through consecutive repeated measurements of Hb concentration in the blood during infusion. It could be applied to evaluate and guide crystalloid fluid rehydration for patients with dehydration or hypovolemia and during anesthesia or surgery. Volume dynamics could be also used to quantificate of strains, hypovolume, and the change of fluid distribution and elimination caused by anesthesia or surgery. The factors which influence the volume resuscitation are complex, including gender, age, hemodynamic state [mean arterial pressure (MAP)], health and stress state, renal function, consciousness, surgical or anesthesia state and so on, which may affect the half-life, distribution, and volume of the fluid. This article summarizes and analyzes the pathophysiological changes of crystalloids fluid in vivo, in order to provide reference for volume management in critically ill patients.

Maternal and cord blood parameters are associated with placental and newborn outcomes in indigenous mothers: A case study in the MINDI cohort / Parámetros maternos y de sangre de cordón asociados con medidas placentarias y del recién nacido: Un estudio de casos en madres indígenas de la cohorte MINDI

Abstract Background: Multiple infections, nutrient deficiencies and inflammation (MINDI) occur in indigenous communities, but their associations with perinatal outcomes have not been described. Objective: To assess maternal and cord blood micronutrient and inflammation status in peripartum mothers from the Ngäbe-Buglé comarca in Panama, and their associations with placental and infant outcomes. Methods: In 34 mother-newborn dyads, placental weight and diameter were measured, and maternal and cord blood were processed for complete cell counts, serum C-reactive protein, ferritin, serum transferrin receptor (sTfR), vitamins A and D. Blood volumes were calculated using Nadler's formula. Results: Mothers had low plasma volume (<2.8 L, 96%), vitamin A (52.9%), vitamin D (29.4%), iron (58.8%) and hemoglobin (23.5%), but high hematocrit (>40%, 17.6%) and inflammation (C-reactive protein >8.1 mg/L, 85.3%). Birthweights were normal, but low placental weight (35.3%), low head circumference Z-scores (17.6%), and low cord hemoglobin (5.9%), iron (79.4%), vitamin A (14.7%) and vitamin D (82.3%) were identified. Maternal and cord vitamin D were highly correlated. Higher maternal plasma volume was associated with heavier placentae (β= 0.57), and higher cord D (β= 0.43) and eosinophils (β= 0.43) with larger placentae. Hemoconcentration (higher cord hematocrit) was associated with lower newborn weight (β= -0.48) and head circumference (β= -0.56). Inflammation [higher maternal neutrophils (β= -0.50), and cord platelets (β= -0.32)] was associated with lower newborn length and head circumference. Conclusion: Maternal-newborn hemoconcentration, subclinical inflammation and multiple nutrient deficiencies, particularly neonatal vitamin D deficiency, were identified as potential targets for interventions to improve pregnancy outcomes in vulnerable communities.

Resumen Antecedentes: Las Múltiples Infecciones, Nutrición Deficiente e Inflamación (MINDI), son frecuentes en comunidades indígenas, sin embargo, sus asociaciones con resultados de salud perinatales no han sido descritos. Objetivo: Evaluar la inflamación y los micronutrientes en sangre materna y de cordón de madres en trabajo de parto en la comarca Ngäbe-Buglé en Panamá, así como sus asociaciones con medidas placentarias y del recién nacido. Métodos: En 34 pares madre-recién nacido, se midieron peso y diámetro placentario, y se analizaron muestras de sangre materna y de cordón umbilical para hemograma completo, proteína-C reactiva (PCR), ferritina, receptor sérico de transferrina (RsTf), vitaminas A y D. Se usó la fórmula de Nadler para calcular volúmenes sanguíneos. Resultados: Las madres presentaron volumen plasmático (<2.8 L, 96%), vitamina A (52.9%), vitamina D (29.4%), hierro (58.8%) y hemoglobina (23.5%) bajos, pero el 17.6% presentaron hematocrito >40% y 85.3% presentaron inflamación (PCR >8.1 mg/L). Los pesos al nacer fueron normales, pero se identificó bajo peso placentario (35.3%), bajo puntaje-z de circunferencia cefálica neonatal, y en sangre de cordón, bajos hemoglobina (5.9%), hierro (79.4%), vitamina A (14.7%) y vitamina D (82.3%). Se encontró una fuerte correlación positiva entre la vitamina D materna y de sangre de cordón. Un mayor volumen plasmático materno se asoció con placentas de mayor peso (β= 0.57), en tanto que concentraciones más altas de vitamina D (β= 0.43) y mayor número de eosinófilos (β= 0.43) se asociaron con mayor diámetro placentario. Una mayor hemoconcentración (hematocrito en cordón más alto) se asoció con menores peso al nacer (β= -0.48) y circunferencia cefálica (β= -0.56). La inflamación [mayor número de neutrófilos maternos (β= -0.50) y plaquetas en sangre de cordón (β= -0.32)] se asoció con menor talla y circunferencia cefálica neonatales. Conclusión: La hemoconcentración materna y del recién nacido, la inflamación subclínica y las múltiples deficiencias en micronutrientes, particularmente la deficiencia de vitamina D neonatal, se identificaron como potenciales áreas de intervención para mejorar los resultados de salud del embarazo en comunidades vulnerables.

Patient posture for blood collection by venipuncture: recall for standardization after 28 years

ABSTRACT Background: Although data about the effect of posture on routine hematological testing were published 28 years ago, this pre-analytical issue has not been standardized so far. This study was planned to evaluate whether postural changes influence the results of hematology testing. Methods: A complete blood count was performed in 19 healthy volunteers after 25 min in the supine position, 20 min in a sitting position and 20 min stationary standing in an upright position. Results: The change from supine to sitting position caused clinically significant increases in the hemoglobin, hematocrit and red blood cell count. Furthermore, the change from supine to standing caused clinically significant increases in the hemoglobin, hematocrit, red blood cell, leukocyte, neutrophil, lymphocyte, basophil and platelet counts, and mean platelet volume, and that from sitting to standing caused clinically significant increases in hemoglobin, hematocrit, and red blood cell, leukocyte, neutrophil and lymphocyte counts. Conclusion: The results of this investigation provide further support to the notion that effort should be made to achieve widespread standardization in the practice of phlebotomy, including patient posture.

Noradrenaline and dobutamine effects on the volume expansion with normal saline in rabbits subjected to hemorrhage

ABSTRACT PURPOSE: To evaluate the effects of dobutamine (DB), noradrenaline (NA), and their combination (NADB), on volume retention in rabbits submitted to hemorrhage. METHODS: Thirty six rabbits were randomly divided into 6 groups: SHAM, Control, Saline, DB, NA, DB+NA. All the animals, except for SHAM, were subjected to hemorrhage of 25% of the calculated blood volume. Control animals were replaced with their own blood. The other groups received NSS 3 times the volume withdrawn. The intravascular retention, hematocrit, diuresis, central venous pressure, mean arterial pressure, NGAL, dry-to-wet lung weight ratio (DTWR) and the lung and kidney histology were analyzed. RESULTS: Replacement with NSS and NA, DB or NA+DB did not produce differences in the intravascular retention. After hemorrhage, the animals presented a significant decrease in the MAP and CVP, which were maintained until volume replacement. Regarding NGAL, dry-to-wet-lung-weight ratio, lung and kidney histology, there were no statistical differences between the groups. CONCLUSION: The use of noradrenaline, dobutamine or their combination did not increase the intravascular retention of volume after normal saline infusion.

Comparación de concentración mínima inhibitoria y concentración plasmática de cefalotina mediante un modelo matemático / Comparison of the minimal inhibitory concentration and the plasma cephalotin concentration through a mathematical model

Introducción: el uso de fármacos fuera de rangos terapéuticos es un problema hospitalario, pues pocas veces se tienen en cuenta parámetros antropométricos del paciente, determinantes en las concentraciones del medicamento. Objetivo: aplicar un modelo matemático basado en parámetros del paciente, para determinar las posibles concentraciones plasmáticas de cefalotina y compárarlas con las concentraciones mínimas inhibitorias de los microrganismos aislados. Métodos: se seleccionó un grupo de pacientes del sexo masculino entre 18 y 50 años de edad con tratamiento profiláctico posquirúrgico con cefalotina. Se recopiló la información: dosis de cefalotina, peso, talla, edad, hematócrito. Se calcularon volumen extracelular, plasmático y sanguíneo según el modelo informado por Hedin. Luego se calculó la concentración plasmática de cefalotina usando el modelo propuesto en el presente estudio y se comparó con la concentración mínima inhibitoria de los microorganismos aislados. Resultados: se analizaron 24 pacientes con promedio de edad 32,6 años ± 8, peso de 69 kg ± 7,51, talla de 168,87 cm ± 7,10. El 56,3 por ciento de los microorganismos presentó resistencia a concentraciones ³ 32 µg/mL. El agente más común fue Escherichia coli de 18 cepas aisladas. La comparación del volumen de distribución y la concentración plasmática de cefalotina calculada con el modelo informado por Hedin y el desarrollado en presente trabajo, no presentó diferencia significativa después de aplicar la prueba t de Student, con p< 0,05. Conclusiones: al comparar las concentraciones teóricas de cefalotina para uso profiláctico posquirúrgico intrahospitalario, calculadas con el modelo planteado, se encontró que estas no permitieron superar la concentración mínima inhibitoria de los microorganismos aislados(AU)

Introduction: the use of drugs out of therapeutic ranges is a hospital problem since the anthropometric parameters of patients, which are determinants in the drug concentrations, are rarely taken into consideration. Objectives: to implement a mathematical model based on the patient's parameters in order to determine the possible plasma cephalotine concentrations and to compare them with the minimum inhibitory concentrations for isolated microorganisms. Methods: a group of male patients aged 18 to 50 years under postsurgical prophylactic treatment with cephalotine was selected. Data was collected on cephalotin dosage, weight, size, age and hematocrit. Extracellular, plasma and blood volumes were estimated by the Hedin's informed model. Additionally, the plasma cephalotin concentration was measured by using the model suggested in this study and then compared with the minimum inhibitory concentration for the isolated microorganisms. Results: twenty four patients aged 32.6 years ± 8, weighing 69 kg ± 7.51, with size of 168.87 cm ± 7.10 were analyzed. Resistance to concentrations equal to or higher than 32 µg/mL was observed in 56.3 percent of microorganisms. The most common agent was Escherichia coli in 18 isolated strains. The comparison of the distribution volume and of the plasma cephalotin concentration estimated with the Hedin's informed model and with the model devised in the present paper did not show significant differences according to Student's t test result, with p< 0.05. Conclusions: the comparison of the theoretical concentrations of cephalotine for in-hospital postsurgical prophylactic use estimated by the model yielded that these concentrations did not allow overcoming the minimum inhibitory concentration for the isolated microorganisms(AU)

Equações para estimar o volume do plasma: um breve relato histórico e considerações sobre a utilização destas em estudos sobre o exercício físico / Equations to estimate the volume of plasma: a brief history and considerations on its use in research about exercise

Introdução. Estimar o volume do plasma sanguíneo ou sua variação pode diretamente implicar a forma de interpretação dos resultados, bem como discussão sobre estes e sua utilização. Objetivo. Apresentar de forma sistemática e cronológica essas equações como auxílio para sua escolha e utilização. Método. Realizou-se revisão sistemática de literatura com o uso das bases de dados eletrônicos National Library of Medicine (Medline/PubMed), Literatura Latino-Americana e do Caribe em Ciência da Saúde (Lilacs), Scientific Electronic Library Online (SciELO), EBSCO SPORTDiscus, Science Direct e Scopus (Elsevier). Para as buscas foramutilizados os seguintes descritores na língua inglesa: exercise, plasma volume, blood volume, blood volume determination, hemoglobin, hematocrit, hemoconcentration. Resultados. Atualmente o volume total do sangue e ou o volume do plasma tem sido medido nos estudos, principalmentepor métodos que se baseiam em marcadores usados de forma intravenosa ou de alguns componentes de marcadores como o corante azul de Evans e a coloração indocianina verde. Uma das formas mais utilizadas para medir o volume do plasma, bem como sua variação, são as equações de predição que levam em conta o valor do hematócrito e ou da concentração da hemoglobina do sangue periférico. Estas equações podem ser usadas com segurança, respeitando-se as condições para quais foram desenvolvidas.

Introduction. Estimating the blood plasma volume or its variation may directly influence the form of interpretating the results, its discussion and how to use them. Objective. The purpose of this study was to introduce a systematic and chronological order of these equations to help in the selection and use thereof. Method. A systematic review of literature was accomplished with the use of electronic databases National Libraryof Medicine (MEDLINE/PubMed), the Latin American and Caribbean Center on Health (LILACS), Scientific Electronic Library Online (SciELO) SPORTDiscus EBSCO, Science Direct and Scopus (Elsevier). For the search we used the following descriptors in English: exercise, plasma volume, blood volume, blood volume determination, hemoglobin,hematocrit, hemoconcentration. Results. Currently the total blood volume and or the plasma volume has been measured in studies mainly bymethods that rely on markers used intravenously or in components of the dye markers such as Evans blue and indocyanine green staining. One of the methods widely used to measure the plasma volume and also its variation are predictive equations that take into account the value of haematocrit and or hemoglobin concentration in peripheralblood. These equations can be used safely while respecting the conditions which they have been developed for.

Efeitos da desidratação sobre desempenho de força de atletas de jiu-jitsu / Effects of dehydration on strength performance of Brazilian Jiu-jitsu fighters

Estratégias destinadas a rápida e drástica redução de peso são comumente adotadas por atletas que competem em eventos de combate esportivo. Portanto, o objetivo do estudo foi determinar o efeito agudo da desidratação induzida por sauna sobre a força e a resistência muscular de atletas de Jiu-jitsu. Onze atletas foram submetidos a um teste de força dinâmica máxima (1RM) no Leg Press nas condições de euhidratação (EH) e desidratação (DES – ~2% do peso) induzida por sauna seca. Em um protocolo adicional, seis voluntários dos onze iniciais também foram submetidos a um teste de resistência muscular localizada (número máximo de repetições com 60% de 1RM no exercício supino reto) e a análise de amostragem sanguínea em ambas as condições (EH e DES). A redução na massa corporal de aproximadamente 2,1% não induziu efeito deletério significativo sobre a força dinâmica máxima (EH 307,72 ± 87,7 kg vs. DES 306,27 ± 88,3 kg; P = 0,148) e a resistência muscular localizada (EH = 29 ± 4 repetições; DES = 28 ± 4 repetições; P= 0,180). Embora a desidratação tenha causado uma redução de 7,6 ± 1,5% no volume plasmático, a concentração de bicarbonato sanguíneo não mudou significativamente (27,2 ± 7,5 vs. 27,5 ± 7,2 mEq/L, condições EH e DES, respectivamente). Concluindo, a desidratação moderada induzida por sauna não afetou significativamente a força e a resistência muscular, além de não induzir alterações nas variáveis bioquímicas associadas ao desempenho de endurance.

Athletes who compete in combat sports events commonly adopt strategies aimed to a fast and drastic weight loss. Therefore, the purpose of this study was to determine the acute effect of sauna- induced dehydration on strength and endurance performance of Brazilian Jiu-jitsu athletes. Eleven athletes performed a one-repetition maximum test (1RM) on a Leg Press exercise in two different hydration states, euhydration (EH) and dry sauna-induced dehydration (DES - 2% of body mass). Additionally, six of the eleven athletes were also submitted to a muscle endurance test (the maximum number of repetitions at 60% of 1RM on a bench press exercise). Blood samples were withdrawn from the same subsample in both hydration conditions. An approximate body mass reduction of 2.1% did not induce a significant deleterious effect on either muscular strength (EH 307.72 ± 87.7 kg vs. DES 306.27 ± 88.3 kg; P = 0.148) or endurance (EH = 29 ± 4 repetitions; DES = 28 ± 4 repetition; P = 0.180). Although dehydration has induced a plasma volume reduction of 7.6 + 1%, plasmatic bicarbonate concentration did not change (EH = 27.2 ± 7.5 vs. DES = 27.5 ± 7.2 mEq/L for EH and DES, respectively). In conclusion, sauna-induced moderate dehydration did not significantly affect either muscular strength or endurance. In addition, no changes were induced on biochemical variables related to the endurance performance.

Expansión volumttrica y comportamiento del oligoamnoss / Volumetric expansion and behavior of the oligoamnios

Con el objetivo de demostrar la efectividad de la expansión volumétrica materna en el incremento del volumen de líquido amniótico en pacientes con tiempo de gestación de 28 a 39 semanas y oligoamnios, mediante la infusión endovenosa con soluciones isotónicas, se realizó una investigación de intervención-acción, analítica y de cohorte en el Hospital "Abel Santamaría" durante el año 2007. Se seleccionó un grupo estudio conformado por las embarazadas con tiempo de gestación de 28 a 39 semanas, con oligoamnios, a las que se les indicó expansión volumétrica (n=125) y dos grupos de control: el primero conformado por las embarazadas sin oligoamnios y que parieron en ese mismo período (n=125); el segundo, por las embarazadas con oligoamnios detectado a las 40 semanas y más de gestación y que no tuvieron posibilidad de la expansión volumétrica (n=125) y finalmente, la muestra quedó constituida por 375 gestantes. En el análisis estadístico se utilizó el porcentaje y el Ji cuadrado al 95% de certeza. Se obtuvo un incremento del índice de líquido amniótico (ILA) en el 96,8% de las gestantes posterior a 3 dosis de tratamiento, las principales causas de cesárea fueron: el sufrimiento fetal agudo, la presentación pelviana e inducción fallida asociado a bajo índice de inducciones y nacimientos pretérminos con morbilidad neonatal baja. Por lo que se concluye que la expansión volumétrica es una opción terapéutica eficaz en el tratamiento del oligoamnios, pues permitió prolongar el embarazo sin incremento de la morbilidad neonatal.

An intervention-action, analytical and cohort research was conducted at "Abel Santamaria Cuadrado" University Hospital-2007, aimed at showing the effectiveness of maternal volumetric expansion in the increase of the amniotic-fluid volume in 28-39 weeks-pregnant women presenting oligoamnios by means of intravenous infusion with isotonic solutions. The study group was comprised of 28-39 weeks-pregnant women presenting oligoamnios, to whom volumetric expansion was indicated (n=125) and two control groups: the first comprised of pregnant women without oligoamnios and delivering in the same period (n=125); the second group of pregnant women that presented oligoamnios detected at 40 weeks or more of pregnancy and without the possibility of volumetric expansion (n=125), 375 pregnant women were in the final sample. To the statistical analysis the percentage method and the chi-square test with 95% of certainty were used. An increase was obtained in the amniotic-fluid rate (AFR), 96, 8% of the pregnant women after the third dose of treatment, the main causes to perform the cesarean section were: acute fetal distress, pelvic presentation and failed labor induction associated to a low rate of induction and preterm births with low neonatal morbidity. Concluding that; volumetric expansion is an efficient therapeutic option in the treatment of oligoamnios, extending pregnancy without increasing neonatal morbidity.

Influencia de la ingesta ad libitum de bebidas con diferente osmolaridad sobre algunas variables fisiológicas durante una actividad física de alta intesidad y larga duración / Influence of ad libitum intake of beverages with diferent osmolarities on some physiological parameters during a high-intensity, long-duration physical activity

OBJETIVO: establecer la influencia de la ingesta ad libitum de diferentes bebidas hidratantes sobre el porcentaje de pérdida del peso corporal (PC), el aumento de la frecuencia cardíaca (FC) y la reducción porcentual del volumen plasmático (porcentaje VP) en deportistas sometidos a una actividad física de alta intensidad y larga duración. METODOLOGÍA: luego de nueve minutos de calentamiento, en banda rodante con velocidad equivalente al 50 por ciento de la frecuencia cardíaca de reserva (FCR), siguieron 88 minutos de carrera, durante la cual la velocidad se incrementó al 80 por ciento de la FCR; al final, 90 minutos de recuperación. No se hizo reposición hídrica durante el tratamiento deshidratado (DH); durante los tratamientos con hidratación se emplearon volúmenes similares, ingeridos ad libitum, de cada una de tres bebidas, a saber: hiperosmolar (Hiper), hipoosmolar (Hipo) e isoosmolar (Iso). RESULTADOS: se observó en cada uno de los tratamientos un aumento del porcentaje de pérdia del peso corporal (PC) (p<0,001) y de la FC (p< 0,05) al igual que una correlación entre el porcentaje PC y el incremento de la FC (p<0,000); en los tratamientos DH e Hiper hubo una reducción del volumen plasmático (VP) (p<0,05). Se observó interacción tiempo tratamiento con el porcentaje PC. CONCLUSIONES: la ingesta ad libitum fue menor que la cantidad recomendada en la literatura internacional, por lo que, probablemente, no se pudieron establecer los efectos de la osmolaridad de las bebidas hidratantes sobre las variables estudiadas. La magnitud del porcentaje PC, del incremento de la FC y de la reducción del porcentaje VP fueron proporcionales a la duración de la actividad física; la relación existente entre el porcentaje PC y la porcentaje VP se modificó por la osmolaridad de la bebida.

OBJETIVE: To establish the influence of ad libitum intake of hydrating beverages with different osmolarities on the percentage of body weight loss (%BW), the increase of heart rate (HR), and the percentage of plasma volume decrease (%PV) in athletes during a high-intensity and long-time run. METHODOLOGY: After 9 warm-up minutes on a treadmill at a speed equivalent to 50% of the heart rate reserve, the athletes performed a run at 80% of the heart rate reserve speed, followed by 90 minutes of recovery. During the "dehydrated treatment" no fluid replacement was given, but during the "hydrated treatments" similar volumes were ad libitum drunk of each of three hydrating beverages, namely hyperosmolar (Hiper), hypoosmolar (Hipo) and isoosmolar (Iso). RESULTS: In all treatments there were increases of the percentage of body weight loss (%BW) (p < 0.001) and of the HR (p < 0.05), and there was a correlation between the %BW and the increase of HR (p < 0.000); in the DH and Hyper treatments a decrease of the percentage of plasma volume loss (%PV) (p < 0.05) was observed. An interaction treatment-time with the %WB was observed. CONCLUSIONS: Ad libitum intake of rehydrating beverages was less than the amount recommended in the international literature. That may have been the reason why the effects of osmolarity of such beverages on the analyzed parameters could not be determined. The amount of the %BW, the HR increase and the %PV decrease were proportional to the duration of physical activity. The relationship between the % BW and the %PV was modified by the osmolarity of beverages

Efectos de la ingesta ad libitum de bebidas hidratantes sobre el peso corporal, la frecuencia cardíaca y el volumen plasmático durante una actividad física de alta intensidad y larga duración: informe preliminar / Body weight, the heart rate, and the plasma volume during a high-intesity, long-duration run

Objetivo: determinar la magnitud de la ingesta ad libitum de tres bebidas hidratantes de diferente osmolaridad y establecer sus efectos sobre el porcentaje de pérdida del peso corporal (PC), el aumento de la frecuencia cardíaca (FC) y la reducción porcentual del volumen plasmático (VP) en nueve deportistas, con entrenamiento aeróbico, sometidos, bajo condiciones ambientales neutras, a una actividad física de alta intensidad, ?80 por ciento de la FC de reserva (FCR80)? y larga duración ?88 minutos?.Metodología: el protocolo experimental se realizó en banda rodante, luego de nueve minutos de calentamiento, a una velocidad equivalente al 50 por ciento de la FCR y con una pendiente del 1 por ciento; siguieron 88 minutos de carrera, en tres intervalos, los dos iniciales de 29 minutos y el último de 30; la pendiente se mantuvo y la velocidad se incrementó al 80 por ciento de la FCR; finalmente, 90 minutos de recuperación, en tres intervalos de 30 minutos cada uno. No se hizo reposición hídrica durante el tratamiento deshidratado (DH); durante los tratamientos con hidratación se empleó un volumen similar de tres bebidas de diferente osmolaridad (H-I, H-II, H-III), el cual fue ingerido ad libitum.Resultados: durante la etapa de ejercicio la pérdida hídrica fue de 1.440 ml/h mientras que el volumen ingerido fue de 407 ml/h. Se observó, en cada uno de los tratamientos, una pérdida porcentual del PC (p<0,001); un incremento de la FC (p<0,05), y excepto con H-II y H-III una reducción porcentual del VP (p<0,05). No hubo diferencias intertratamientos en el porcentaje de la pérdida del PC, en el aumento de la FC ni en la reducción porcentual del VP.Conclusiones: la ingesta ad libitum fue menor que la cantidad recomendada internacionalmente por lo que, probablemente, no se pudieron establecer los efectos de la osmolaridad de las bebidas hidratantes sobre las variables estudiadas. Estos hallazgos nos obligan a revisar las prácticas de hidratación de nuestros deportistas ya que, al parecer, no ingieren la cantidad adecuada de líquidos para obtener los beneficios atribuidos a la hidratación.

Objetive: to determine the amount of ad libitum intake of three rehydrating beverages of different osmolalities, and to establish their effects on the percentage of body weight loss, the increase of heart rate and the reduction of plasma volume, in nine subjects with aerobic training, during a highintensity,long-duration run. Methodology: the experiment was carried out on a treadmill with 1% of inclination that was kept constant throughout the procedure; it started with 9 minutes of warm-up at a speed equivalent to 59% of the reserve heart rate; then, 88 minutes of running divided in three intervals (29, 29, and 30 minutes) at 80% of the reserve heart rate; finally, 90 minutes of recovery in three intervals of 30 minutes each. During the "dehydrated treatment" no fluid replacement was done; during the "Hydrating treatments" (H-I, H-II, H-III) equivalent volumes were drunk of the aforementioned rehydrating beverages. Results: during the exercise period the fluid loss was 1.440 ml/h. In each one of the treatments there was a loss of body weight (p<0.001), an increase of heart rate (<0.05) and, except for HII and H-III, a reduction of plasma volume (p<0.05). There were no differences between the treatments in these three parameters. Conclusions: ad libitum intake was less than the amount internationally recommended; probably that explains that the effects of osmolality of the rehydrating beverages on the analyzed parameters could not be determined. These findings ought to motivate a review of the hydrating practices of our athletes because, seemingly, they are not ingesting an adequate amount of fluids to obtain the benefits attributed to hydration.

El cálculo del volumen plasmático mediante las curvas de aclaramiento de la transferrina marcada con 59Fe / The calculation of plasma volume by the clearance curves of the trasnferrin marked with Fe

Se calculó el volumen plasmático con transferrina marcada con 59Fe (Tf-59Fe) en 2 grupos de pacientes, uno con policitemia vera (PV) y otro con policitemia relativa (PR), mediante 2 procedimientos: con el valor de la actividad a tiempo cero obtenida por regresión y con los recuentos por minuto de una muestra extraída a los 3 minutos posteriores a la inyección de la Tf-59Fe. En todos los casos la actividad a tiempo cero fue mayor que la actividad de la muestra a los 3 min. Los valores del volumen plasmático calculados por el primer procedimiento fueron menores. Las diferencias en el grupo con PV fueron significativamente mayores que las encontradas en el grupo con PR. Este estudio refuerza la utilidad de calcular la distribución de la Tf-59Fe a tiempo cero, cuando esta se ha mezclado homogéneamente en la circulación y los cambios de la curva de aclaramiento son menos críticos.

The plasma volume was calculated with transferrin marked with 59Fe (Tf-59FE) in 2 groups of patients, one with polycythemia vera and the other with relative polycythemia (RP), by using 2 methods: with the value of the activity at zero time obtained by regresssion and with the recounts per minute of a sample taken 3 minutes after the injection of Tf-59Fe. In all the cases, the activity at zero time was higher than the activity of the sample 3 minutes later. The values of plasma volume calculated by the first method were lower. The differences in the group with PV were significantly higher than the ones found in the group with RP. This study confirms the usefulness of calculating the distribution of Tf-59Fe at zero time when this has been homogeneously mixed in the circulation and the changes in the clearance curve are less critical.

Effects of carbohydrate and electrolyte solution replacement on metabolic and hormonal responses after a moderate endurance run in hot outdoor conditions / 体力科学

The effect of ingestion of a chilled carbohydrate and electrolyte solution on metabolic and hormonal responses and water-electrolyte balance was studied after two 5-km runs in hot outdoor conditions (Temp, 30.6-30.9°C ; humidity, 61.3-62.4%) . Eight healthy females (mean age 21.8 years) participated in : 1) a control experiment (Copt) with no fluid intake, 2) an experiment with 500 ml of tap water (WI), and 3) an experiment with 500 ml of sports beverage (SB) containing carbohydrate and electrolytes each of which were given after the 1st 5-km run, followed by a second 5-km run with an equivalent to 68.7-72.3% of VO<SUB>2</SUB>max. In the Cont, decreases in %ΔPV and blood glucose (BS) and increases in serum osmolality (Sosm), free fatty acid (sFFA) and plasma hormone concentrations related to regulation of the water-electrolyte balance in the body persisted after the 2 nd run. The intake of the sports beverage prevented hypoglycemia and ketoacidosis, as shown by an increase in sFFA and positive results for qualitative analysis of ketone body in the urine, and quick recovery of plasma volume following an endurance run under a hot environment. This study suggests that fluid replacement with a sports beverage containing carbohydrate and electrolytes was superior to plain water or no fluid ingestion in terms of metabolic and hormonal responses and the recovery of plasma volume and elevated rectal temperature following an endurance run under hot conditions.

Cardiovascular function during kendo exercise in a hot environment. Effects of water replacement / 体力科学

A study was carried out to examine the effects of water replacement on cardiovascular function during kendo practice in a hot environment. Five male college kendoists performed moderately severe 30-min kendo practice at a WBGT index of about 27°C with and without water intake. For water replacement, the subjects ingested 700 ml water (500 ml before exercise and 200 ml at 15 min after the start of exercise) . Under both conditions, body weight was decreased significantly, and hematocrit and serum total protein concentration were increased significantly after the exercise. With water replacement, the body weight loss induced by the exercise was similar to that under water deprivation. However, the decrease in body weight from the basal body weight, i. e. body weight measured before water intake, was significantly less with water replacement than under water deprivation. There were no significant differences in the percentage increases of hematocrit and serum total protein concentration between the two conditions, although the percentage change in plasma vasopressin concentration was significantly lower with water replacement than without. In the subjects deprived of water, the left ventricular end-diastolic dimension and left atrial dimension were significantly reduced after the exercise, and stroke volume, ejection fraction, and fractional shortening were also decreased significantly. The ratio of left ventricular end-systolic wall stress to left ventricular end-systolic volume index was increased significantly after the exercise without water intake. With water replacement, however, the percentage decreases in cardiac dimensions, stroke volume, ejection fraction, and fractional shortening were significantly lower than those under water deprivation. There was no significant change in the ratio of left ventricular end-systolic wall stress to left ventricular end-systolic volume index before and after the exercise with water intake. It is suggested that 700 ml water replacement before and during kendo exercise in a hot environment prevents depletion of stroke volume and deterioration of cardiovascular function, although it might not improve significantly the plasma volume loss after exercise.