Ultrassonografia da veia cava inferior na avaliação do volume intravascular e fluido-responsividade em pacientes críticos: uma revisão sistemática / Inferior vena cava ultrasound for assessing volume status and fluid responsiveness in critically ill patients: a systematic review

Fundamento: A avaliação do volume intravascular e da fluido-responsividade é uma condição desafiadora no manejo de pacientes críticos. Os métodos diagnósticos precisam garantir segurança, reprodutibilidade e praticidade no monitoramento hemodinâmico. Objetivo: Descrever a aplicabilidade dos índices ultrassonográficos da veia cava inferior na avaliação do volume intravascular e na predição da fluido-responsividade em pacientes críticos. Método: Trata-se de revisão sistemática realizada por meio das bases de dados PubMed®, Lilacs e SciELO nos 5 anos anteriores. Os descritores utilizados foram "inferior vena cava", "ultrasonography", "fluid-responsiveness" e "volume status". Resultados: Foram selecionados 13 artigos compatíveis com os objetivos deste estudo. O índice de colapsibilidade da veia cava inferior variou de 25% a 50% como ponto de corte para definição de hipovolemia. Além disso, apresentou aplicabilidade na predição da fluido-responsividade em pacientes sob respiração espontânea, com pontos de corte variando de 25% a 57%. Em cenários de ventilação mecânica, o índice de distensibilidade da veia cava inferior mostrou-se mais eficaz, quando comparado às demais medidas, para predição de fluido-responsividade, mas foi encontrada variação de 10,2% a 20,5%. O índice diâmetro da veia cava inferior/diâmetro da artéria aorta foi especialmente útil na população pediátrica para definição do volume intravascular, mas em adultos existiram muitas divergências quanto à sua aplicabilidade. Conclusão: A avaliação do volume intravascular e da fluido-responsividade por meio dos índices ultrassonográficos da veia cava inferior apresenta aplicabilidade e segurança no diagnóstico e no monitoramento da instabilidade hemodinâmica. Entretanto, são necessários estudos de padronização de valores em razão das divergências quanto aos pontos de corte utilizados em cada índice.(AU)

Prehospital Damage Control: The Management of Volume, Temperature… and Bleeding! / Control de Daños Prehospitalario: ¡Para Los Cristaloides, Para La Hipotermia Y…! ¡Para El Sangrado!

Abstract Damage control resuscitation should be initiated as soon as possible after a trauma event to avoid metabolic decompensation and high mortality rates. The aim of this article is to assess the position of the Trauma and Emergency Surgery Group (CTE) from Cali, Colombia regarding prehospital care, and to present our experience in the implementation of the "Stop the Bleed" initiative within Latin America. Prehospital care is phase 0 of damage control resuscitation. Prehospital damage control must follow the guidelines proposed by the "Stop the Bleed" initiative. We identified that prehospital personnel have a better perception of hemostatic techniques such as tourniquet use than the hospital providers. The use of tourniquets is recommended as a measure to control bleeding. Fluid management should be initiated using low volume crystalloids, ideally 250 cc boluses, maintaining the principle of permissive hypotension with a systolic blood pressure range between 80- and 90-mm Hg. Hypothermia must be management using warmed blankets or the administration of intravenous fluids warmed prior to infusion. However, these prehospital measures should not delay the transfer time of a patient from the scene to the hospital. To conclude, prehospital damage control measures are the first steps in the control of bleeding and the initiation of hemostatic resuscitation in the traumatically injured patient. Early interventions without increasing the transfer time to a hospital are the keys to increase survival rate of severe trauma patients.

Resumen La resucitación en el control de daños debe iniciarse lo más rápido posible después de presentado el evento traumático para evitar descompensación metabólica y aumento de la mortalidad. El objetivo de este artículo es sustentar nuestro enfoque respecto a la atención prehospitalaria y presentar nuestra experiencia en la implementación de la iniciativa "Stop the Bleed" en Latinoamérica. La atención prehospitalaria es la fase Cero de la resucitación del control de daños. Por medio de la implementación de la iniciativa "Stop the Bleed" se identificó que el personal prehospitalario tiene una mejor percepción sobre el uso de técnicas hemostáticas como el torniquete que el personal hospitalario. Se recomienda el uso de torniquetes como medida de control de sangrado en extremidades. El manejo de líquidos debe realizarse usando cristaloides a bajos volúmenes, con bolos de 250 mL para cumplir el principio de la hipotensión permisiva con un rango entre 80 y 90 mm Hg de presión arterial sistólica. Se deben realizar medidas para evitar la hipotermia como el uso de sábanas térmicas o paso de líquidos calientes. Estas medidas no deben retrasar en ningún momento el tiempo de traslado para recibir la atención hospitalaria. En conclusión, la atención prehospitalaria es el paso inicial para garantizar las primeras medidas de control de sangrado y de resucitación hemostática de los pacientes. Realizar intervenciones tempranas sin acortar el tiempo de traslado a la atención hospitalaria son las claves para aumentar la tasa de supervivencia.

What Factors can Influence Massive Blood Loss in the Surgical Treatment of Neuromuscular Scoliosis? / Quais fatores podem influenciar perdas sanguíneas extensas no tratamento cirúrgico da escoliose neuromuscular?

Abstract Objective The aim of the present study is to identify the incidence, predisposing factors and prognostic impact of blood loss in patients with neuromuscular scoliosis submitted to corrective surgery. Methods Retrospective cohort study, including pediatric patients diagnosed with neuromuscular scoliosis undergoing instrumentation and posterior vertebral fusion in a university hospital. Patient characteristics were collected from the hospital information system. Results A total of 39 patients were included in the study. The intraoperative blood losses were 962 ml, representing a loss of 35.63% of the blood volume. In 20 cases, there was a massive blood loss (> 30%) and only 7 patients did not need a transfusion. The group of patients with massive blood loss had a slightly higher age (13.75 versus 13.53 years old), a lower body mass index (BMI) percentile (25 versus 50), and for each decrease of 0.38 in the BMI, intraoperative blood losses increased 1% (p < 0.05). The value of preoperative albumin had influence on the percentage of blood loss, and for each decrease of 0.4 of albumin, blood loss increased 1% (p < 0.05). Conclusions The factors that most contributed to the differences in blood loss were age, BMI, and preoperative albumin value. There was no significant association between Cobb angle, number of fusion levels and duration of surgery. We can conclude that these patients would benefit from preoperative nutritional control.

Resumo Objetivo O objetivo do presente estudo é identificar a incidência, os fatores predisponentes e o impacto prognóstico da perda de sangue em pacientes com escoliose neuromuscular submetidos a cirurgia corretiva. Métodos Estudo de coorte retrospectiva, incluindo pacientes pediátricos com diagnóstico de escoliose neuromuscular submetidos a instrumentação e fusão vertebral posterior em um hospital universitário. As características dos pacientes foram coletadas no sistema de informações do hospital. Resultados Um total de 39 pacientes foram incluídos no estudo. As perdas sanguíneas intraoperatórias foram de 962 mL, representando uma perda de 35,63% do volume sanguíneo; a perda de sangue foi extensa em 20 casos (> 30%) e apenas 7 pacientes não necessitaram de transfusão. O grupo de pacientes com perda maciça de sangue apresentou idade um pouco maior (13,75 versus 13,53 anos) e menor percentil do índice de massa corporal (IMC) (25 versus 50); para cada diminuição de 0,38 no IMC, as perdas sanguíneas intraoperatórias aumentaram 1% (p < 0,05). A concentração pré-operatória de albumina influenciou o percentual de perda de sangue e, para cada diminuição de 0,4 de albumina, a perda de sangue aumentou 1% (p < 0,05). Conclusões Os fatores que mais contribuíram para as diferenças na perda sanguínea foram idade, IMC e concentração pré-operatória de albumina. Não houve associação significativa entre ângulo de Cobb, número de níveis de fusão e duração da cirurgia. Podemos concluir que esses pacientes se beneficiariam do controle nutricional pré-operatório.

Impacto del volumen de sangre extraído por flebotomía sobre el requerimiento transfusional en prematuros menores de 1500 g. Estudio cuasiexperimental / Impact of the volume of blood collected by phlebotomy on transfusion requirements in preterm infants with birth weight of less than 1500 g. A quasi-experimental study

Introducción. La anemia es una complicación para los recién nacidos de muy bajo peso al nacer, y los exámenes de laboratorio son un factor de riesgo preponderante. Más del 50 % recibe, al menos, una transfusión de glóbulos rojos. Estas se han asociado a mayor riesgo de infecciones, hemorragia intracraneal, enterocolitis necrotizante y displasia broncopulmonar. En 2012, se implementó, en el Hospital Italiano de Buenos Aires, una estrategia de menor volumen de extracción de sangre por flebotomía. El objetivo del presente estudio fue evaluar su asociación con el número detransfusiones.Métodos. Estudio cuasiexperimental del tipo antes/después. Se comparó el número de transfusiones entre dos grupos de prematuros de muy bajo peso con diferente volumen de extracción. Se evaluó la correlación entre el volumen extraído y el número de transfusiones estimando el coeficiente de Spearman. Para ajustar por confundidores, se realizó un modelo de regresión logística.Resultados. Se incluyeron en el estudio 178 pacientes con edad gestacional media de 29,4 semanas (desvío estándar: 2,7) y peso al nacer de 1145 gramos (875-1345). El perfil de la serie roja inicial fue similar entre ambos grupos. El número de transfusiones (p = 0,017) y el volumen transfundido (p = 0,048) disminuyeron significativamente. El coeficiente de correlación resultó de 0,83. En el análisis multivariado, volumen de extracción y peso al nacer se asociaron a un requerimiento mayor de 3 transfusiones.Conclusión. Un menor volumen de extracción de sangre en prematuros de muy bajo peso está asociado de manera independiente a menor requerimiento transfusional.

Introduction. Anemia is a complication in very low birth weight (VLBW) infants, and lab tests are a predominant risk factor. At least one red blood cell transfusion is given in more than 50 % of cases. Transfusions are associated with a higher risk for infections, intracranial hemorrhage, necrotizing enterocolitis, and bronchopulmonary dysplasia. In 2012, Hospital Italiano de Buenos Aires implemented a strategy to collect a lower blood volume by phlebotomy. The objective of this study was to assess its association with the number of transfusions.Methods. Before-and-after, quasi-experimental study. The number of transfusions was compared between two groups of VLBW preterm infants with different blood collection volumes. The correlation between the collection volume and the number of transfusions was assessed estimating Spearman's coefficient. A logistic regression model was used to adjust for confounders.Results. The study included 178 patients with a mean gestational age of 29.4 weeks (standard deviation: 2.7) and a birth weight of 1145 g (875-1345). The baseline red series profile was similar between both groups. The number of transfusions (p = 0.017) and the transfusion volume (p = 0.048) decreased significantly. The correlation coefficient was 0.83. In the multivariate analysis, collection volume and birth weight were associated with a requirement of more than three transfusions.Conclusion. A lower blood collection volume in VLBW preterm infants is independently associated with fewer transfusion requirements.

Conservation of both hematocrit and liver regeneration in hepatectomies: a vascular occlusion approach in rats / Hepatectomia hemoconservadora no rato: preservação do hematócrito e da regeneração hepática

ABSTRACT Background: Hepatectomies promote considerable amount of blood loss and the need to administrate blood products, which are directly linked to higher morbimortality rates. The blood-conserving hepatectomy (BCH) is a modification of the selective vascular occlusion technique. It could be a surgical maneuver in order to avoid or to reduce the blood products utilization in the perioperative period. Aim: To evaluate in rats the BCH effects on the hematocrit (HT) variation, hemoglobin serum concentration (HB), and on liver regeneration. Methods: Twelve Wistar rats were divided into two groups: control (n=6) and intervention (n=6). The ones in the control group had their livers partially removed according to the Higgins and Anderson technique, while the rats in the treatment group were submitted to BCH technique. HT and HB levels were measured at day D0, D1 and D7. The rate between the liver and rat weights was calculated in D0 and D7. Liver regeneration was quantitatively and qualitatively evaluated. Results: The HT and HB levels were lower in the control group as of D1 onwards, reaching an 18% gap at D7 (p=0.01 and p=0.008, respectively); BCH resulted in the preservation of HT and HB levels to the intervention group rats. BCH did not alter liver regeneration in rats. Conclusion: The BCH led to beneficial effects over the postoperative HT and serum HB levels with no setbacks to liver regeneration. These data are the necessary proof of evidence for translational research into the surgical practice.

RESUMO Racional: As hepatectomias compreendem considerável perda sanguínea e utilização de hemoderivados, o que diretamente estão relacionados com maior morbimortalidade. A hepatectomia hemoconservadora (HH) é modificação da técnica de oclusão vascular seletiva em hepatectomia. Ela pode ser alternativa cirúrgica para evitar ou diminuir o uso de hemoderivados no perioperatório. Objetivo: Avaliar os efeitos da HH sobre o volume globular (VG), concentração de hemoglobina (HB) e sobre a regeneração hepática em ratos. Métodos: Dois grupos de ratos Wistar foram constituídos: controle (n=6) e intervenção (n=6). Os do grupo controle foram submetidos à hepatectomia parcial de Higgins e Anderson e os do grupo Intervenção à HH. VG e HB foram medidos nos dias D0, D1 e D7. A relação peso do fígado/peso do rato foi calculada em D0 e D7. A regeneração hepática foi analisada qualitativamente e quantitativamente. Resultados: Houve diminuição dos níveis de VG e HB nos ratos do grupo controle a partir de D1, atingindo decréscimo de 18% em D7 (p=0,01 e p=0,008 respectivamente); a HH permitiu a manutenção dos níveis de VG e HB nos ratos do grupo intervenção. A HH não alterou a regeneração hepática. Conclusão: HH resultou em níveis maiores de VG e HB pós-operatórios sem alterar a regeneração hepática. Pode-se considerar estes dados como a prova necessária para a translação à pesquisa clinicocirúrgica.

Utilidad del protocolo focused assessment with transthoracic echocardiography (FATE) en la evaluación del paciente con shock / The usefulness of the (FATE) protocol focused assessment with transthoracic echocardiography in patients with shock

Determinar la utilidad del protocolo FATE (Focused Assessment with Transthoracic Echocardiography) en la evaluación de los pacientes en shock. ingresados al Servicio de Cuidados Intermedios del Hospital Central Universitario Dr. "Antonio María Pineda", Barquisimeto, Venezuela en el período agosto-octubre 2019, Métodos: se realizó un estudio descriptivo transversal, de 30 pacientes, con promedio de edad de 56,86 ± 15,85 años, Resultados: predominó el grupo de 71-80 años (23,33%), de sexo masculino (63,33%). Según la clasificación del shock por Weil y Shubin el 50% presentó shock distributivo (todos por sepsis), 20% cardiogénico, 16,67% hipovolémico y obstructivo. 13,33% Los principales hallazgos ecocardiográficos fueron presencia de derrame pleural bilateral (33,33%), derrame pleural unilateral (30%) y derrame pericárdico (23,33%). Además, 26,67% presentaron espesor miocárdico patológico, 33,33% dimensiones de VD-VI aumentadas, 46,67% función sistólica ventricular alterada; sumado al hecho que 70% de la contractibilidad y 60% de la visualización pulmonar eran patológicas. El valor cualitativo del protocolo FATE resultó en: 43,33% soportaba la información disponible, 26,67% añadió información decisiva a la terapéutica, 23,33% agregó nueva información y 6,67% información fue pobre por mala ventana. La mortalidad a los 7 días fue de 43,33%, siendo más frecuente en pacientes con shock distributivo (61,54%), seguido de cardiogénico (23,08%) y obstructivo (15,38%), no hubo defunciones por shock hipovolémico. Los valores cualitativos del protocolo FATE en pacientes fallecidos; por shock distributivo 37,5%, soportó la información disponible y agregó nueva información, respectivamente. En cambio en 100% de los fallecidos por shock cardiogénico y obstructivo, el protocolo FATE añadió información decisiva a la terapéutica. Los resultados demuestran la importancia del Protocolo FATE en el manejo de pacientes con shock(AU)

To determine the usefulness of the FATE protocol (Focused Assessment with Transthoracic Echocardiography) in the evaluation of patients in shock admitted to the Intermediate Care Unit of the "University Hospital Antonio Maria Pineda" in Barquisimeto, Venezuela, during the period August-October 2019, Methods: A descriptive cross-sectional study was done, selecting 30 patients, with an average age of 56.86 ± 15.85 years; the most affected group was 71-80 years old (23.33%), with a predominance of the male sex (63.33%) Results: According to the classification of shock by Weil and Shubin, 50% were found to have distributive shock (all due to sepsis), 20% cardiogenic, 16.67% hypovolemic and obstructive 13.33%. The main echocardiographic findings were the presence of bilateral pleural effusion (33.33%), unilateral pleural effusion (30%) and pericardial effusion (23.33%). In addition, 26.67% presented pathological myocardial thickness, 33.33% increased RV-LV dimensions, 46.67% impaired ventricular systolic function; also, 70% of contractibility and 60% of pulmonary visualization were pathological. The qualitative value of the FATE protocol resulted in: 43.33% supported the available information, 26.67% added decisive information to the therapy, 23.33% added new information and 6.67% information was poor due to a bad US window. (Mortality at 7 days was 43.33%, being more frequent in patients with distributive shock (61.54%), followed by cardiogenic (23.08%) and obstructive (15.38%); there were no deaths due to hypovolemic shock. The qualitative values of the FATE protocol in patients with distributive shock who died, was that 37.5% In contrast, in 100% of those who died by cardiogenic and obstructive shock, the FATE protocol added decisive information to the therapy. Conclusion:The results demonstrate the importance of the FATE Protocol in the management of patients with shock(AU)

Assessment of the prescription of red blood cell concentrates in the pediatric age group / Avaliação da prescrição de concentrados de hemácias na faixa etária pediátrica

Summary Objective: To verify the adequacy of red blood cell (RBC) prescription to pediatric patients in different sectors of a pediatric hospital. Method: A retrospective study was conducted including 837/990 RBC transfusion requisition forms for children and adolescents (0 to 13 years old) filed in between January 2007 and April 2015 by the pediatricians of the emergency room (ER), infirmary ward and intensive care unit (pICU). Transfusion requisition forms belonging to patients with chronic anemia or acute hemorrhage, as well as incompletes requisition forms, were excluded. Results: Trigger, prescribed volume and subtype of RBC concentrates were adequate in 532 (65.3%), 460 (58.8%) and 805 (96.2%) of the transfusions, respectively. When the clinical picture was considered, prescription adequacy was higher compared to the use of the hemoglobin level alone (70.9% vs. 41%). The pICU had the highest correct trigger percentage (343 [71.6%]; p<0.001) while the ER showed more often adequate prescribed volumes (119 [66.1%]; p=0.020). The most common inadequacy regarding volume was that of prescriptions above the recommendation > 15 mL/kg found in 309 cases (36.9%). Thirty-two (32) RBC subtypes were requested and none were consistent with current recommendations. Conclusion: The results obtained in our study showed that RBC transfusion occurred more appropriately when the clinical picture was taken into account at request. There was a tendency to prescribe higher volumes and RBC subtypes without the justification of current protocols. Hemotherapic teachings at undergraduate level and medical residency must be improved.

Resumo Objetivo: Verificar a adequação na prescrição de concentrado de hemácias (CH) por pediatras em diferentes setores de um hospital pediátrico. Método: Realizou-se estudo retrospectivo onde avaliamos 837/990 fichas de requisição de CH para crianças e adolescentes (0 a 13 anos), preenchidas entre janeiro de 2007 e abril de 2015 pelos médicos pediatras do pronto-socorro (PS), da enfermaria e da unidade de terapia intensiva (UTI). Excluíram-se as transfusões realizadas em portadores de anemia crônica, crianças com hemorragia aguda e requisições incompletas. Resultados: Gatilho, volume prescrito e subtipo de concentrado de hemácias foram adequados em 532 (65,3%), 460 (58,8%) e 805 (96,2%) das transfusões, respectivamente. Quando foi considerado o quadro clínico, a adequação foi maior em comparação à prescrição pelo valor isolado da hemoglobina (70,9% vs. 41%). A UTI teve o maior percentual de acerto no gatilho (343 [71,6%]; p<0,001) e o PS, no volume prescrito (119 [66,1%]; p=0,020). A inadequação mais comum, em relação ao volume, foi a prescrição acima da recomendação (> 15 mL/kg, 309 [36,9%]). Foram solicitados 32 subtipos de CH e nenhum estava de acordo com as indicações atuais. Conclusão: Os resultados obtidos mostram que a transfusão de CH aconteceu de forma mais adequada quando a situação clínica era levada em conta na solicitação. Houve uma tendência à prescrição de volumes elevados e de subtipos de hemácias não justificados segundo os protocolos atuais. É necessário melhorar o ensino de hemoterapia na graduação e residência médica.

Hemodinámica funcional: ¿Qué significa "ser respondedor"? / Functional hemodynamics: "Be responsive, what does this mean"?

The conventional analysis and approach to the physiology of the fluid responsiveness has traditionally been focused mainly on the physiology of heart-lung interactions, and on reviews of the technical, methodological, and epidemiological aspects of the dynamic parameters, which are translated into simple algorithms to assess fluid responsiveness and to guide fluid therapy.However, fundamental features of the dynamics of the peripheral circulation, heart-vasculature interaction, and blood volume distribution, are overlooked and sometimes not accounted for, motivating misconceptions about the cardiovascular system's response to fluid administration and fluid management, such as equating fluid loading with cardiac preload, a predictable interpretation whenever Starling's ventricular function curve is analyzed in isolation. This paper reexamines fluid responsiveness' rationale offering a broadened perspective on the circulatory phenomena involved in the physiological interaction between BV, cardiac preload and output, and stroke volume variation. Finally, implications relevant in physiological and clinical terms are discussed.

El análisis convencional y abordaje actual de la fisiología de la "respuesta a fluidos" (RF) ha estado focalizada principalmente sobre la fisiología de la interacción cardiopulmonar, y sobre aspectos técnicos, metodológicos y, epidemiológicos de los parámetros dinámicos, los cuales son traducidos en algoritmos simplificados para evaluar la RF y guiar la fluidoterapia. Sin embargo, aspectos fundamentales de la dinámica de la circulación periférica, el acoplamiento entre el corazón y la vasculatura, y la distribución del volumen sanguíneo son frecuentemente omitidos, motivando mal interpretaciones sobre la respuesta del sistema cardiovascular a la administración de fluidos, tal como equiparar la carga de fluidos con la precarga ventricular, una consecuencia predecible al interpretar la curva de función ventricular (Starling) de forma aislada. Así, esta revisión reexamina la rationale de la RF, ofreciendo una perspectiva ampliada sobre aquellos fenómenos circulatorios implicados en la interacción entre el volumen sanguíneo, la precarga ventricular, el gasto cardíaco y la variación del volumen sistólico. Finalmente, se analizarán las implicancias prácticas y conceptuales.

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.

Serotoninergic Modulation of Basal Cardiovascular Responses and Responses Induced by Isotonic Extracellular Volume Expansion in Rats / Modulação Serotoninérgica de Respostas Cardiovasculares Basais e Induzidas pela Expansão Isotônica do Volume Extracelular em Ratos

Abstract Background: Isotonic blood volume expansion (BVE) induced alterations of sympathetic and parasympathetic activity in the heart and blood vessels, which can be modulated by serotonergic pathways. Objective: To evaluate the effect of saline or serotonergic agonist (DOI) administration in the hypothalamic paraventricular nucleus (PVN) on cardiovascular responses after BVE. Methods: We recorded pulsatile blood pressure through the femoral artery to obtain the mean arterial pressure (MAP), systolic (SBP) and diastolic blood pressure (DBP), heart rate (HR) and the sympathetic-vagal ratio (LF/HF) of Wistar rats before and after they received bilateral microinjections of saline or DOI into the PVN, followed by BVE. Results: No significant differences were observed in the values of the studied variables in the different treatments from the control group. However, when animals are treated with DOI followed by BVE there is a significant increase in relation to the BE control group in all the studied variables: MBP (114.42±7.85 vs 101.34±9.17); SBP (147.23±14.31 vs 129.39±10.70); DBP (98.01 ±4.91 vs 87.31±8.61); HR (421.02±43.32 vs 356.35±41.99); and LF/HF ratio (2.32±0.80 vs 0.27±0.32). Discussion: The present study showed that the induction of isotonic BVE did not promote alterations in MAP, HR and LF/HF ratio. On the other hand, the injection of DOI into PVN of the hypothalamus followed by isotonic BVE resulted in a significant increase of all variables. Conclusion: These results suggest that serotonin induced a neuromodulation in the PVN level, which promotes an inhibition of the baroreflex response to BVE. Therefore, the present study suggests the involvement of the serotonergic system in the modulation of vagal reflex response at PVN in the normotensive rats.

Resumo Fundamento: Expansão de volume extracelular (EVEC) promove alterações da atividade simpática e parassimpática no coração e vasos sanguíneos, os quais podem ser moduladas por vias serotoninérgicas. Objetivo: Avaliar o efeito da administração de salina ou agonista serotoninérgico (DOI) nos núcleos paraventriculares hipotalâmico (NPV) sobre respostas cardiovasculares após EVEC. Métodos: Foram obtidos registros da pressão arterial pulsátil, por meio da artéria femoral, para obtenção dos valores da pressão arterial média (PAM), sistólica (PAS), diastólica (PAD), frequência cardíaca (FC) e razão simpático-vagal (LF/HF) de ratos Wistar antes e após receberem microinjeções bilaterais no NPV de salina ou DOI seguida de EVEC. Resultados: Não foram observadas diferenças significativas dos valores das variáveis estudadas nos diferentes tratamentos do grupo controle. Entretanto, quando os animais são tratados com DOI seguida de EVEC ocorre aumento significativo em relação ao grupo controle com EVEC em todas as variáveis estudadas: PAM (114,42±7,85 vs 101,34±9,17), PAS (147,23±14,31 vs 129,39±10,70), PAD (98,01 ±4,91 vs 87,31±8,61), FC (421,02±43,32 vs 356,35±41,99) e LF/HF (2,32±0,80 vs 0,27±0,32). Discussão: O presente estudo mostrou que a indução de EVEC isotônica não promoveu alterações na PAM, PAD, PAS, FC e LF/HF. Por outro lado, os animais que receberam microinjeção de DOI no NPV seguida de EVEC apresentaram aumento significativo de todas as variáveis. Conclusão: Esses resultados sugerem que a serotonina exerce uma neuromodulação em nivel do NPV, e essa promove uma inibição da resposta barorreflexa frente à EVEC. Assim, o presente trabalho sugere o envolvimento serotoninérgico na neuromodulação no nivel do NPV na resposta reflexa vagal em ratos normotensos.

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.

Medida da pressão venosa central com o paciente em diferentes angulações / Central venous pressure measurement with patient at different angles / Medición de la presión venosa central con el paciente en diferentes ángulos

Objetivo: identificar se existe diferença nos valores da pressão venosa central com a cabeceira do leito do paciente elevada. Método: estudo longitudinal, analítico e de abordagem quantitativa, realizado em quatro unidades de terapia intensiva de um hospital de grande porte do noroeste paulista, de agosto a novembro de 2013. A pressão venosa central foi mensurada em 156 pacientes, em quatro angulações diferentes, totalizando 624 medidas. Os dados são apresentados em números absolutos e percentuais, as variáveis analisadas pelo Teste de Mann-Whitney e Wilcoxon e associação entre as medidas pela análise do coeficiente de correlação de Pearson (r). Conclusão: a mensuração pode ser realizada com acurácia a 0° e 30°, pois apresentaram correlação positiva entre as medidas, porém a 0° e 45° a correlação é fraca, demonstrando pouca associação entre as variáveis.

Objective: to investigate whether central venous pressure values differ with patient bed inclination. Method: this quantitative, analytical, longitudinal study was conducted from November to August 2013 at four intensive care units at a large hospital in northwest São Paulo. Central venous pressure was measured in 156 patients at four different bed inclinations each, totaling 624 measurements. The data are expressed in absolute and percentage values, variables were analyzed using the Mann-Whitney and Wilcoxon tests, and associations between measurements were tested by Pearson's correlation coefficient (r). Conclusion: measurements were found to be accurate at 0° and 30° (a positive correlation between measurements), but a weak correlation at 0° and 45° (revealing little association between the variables).

Objetivo: identificar si existen diferencias de valores de la presión venosa central dependiendo de la altura de la cabecera de la cama del paciente. Método: el estudio es cuantitativo, analítico y longitudinal, realizado en cuatro unidades de cuidados intensivos de un hospital de gran porte, ubicado en el Noroeste del São Paulo entre agosto y noviembre de 2013. Se midió la presión venosa central en 156 pacientes, desde cuatro ángulos diferentes, totalizando 624 mediciones. Los datos se presentan en números absolutos y en porcentajes; las variables fueron analizadas mediante la Prueba de Mann­Whitney­Wilcoxon y la asociación entre las medidas se hizo a través del análisis del coeficiente de correlación de Pearson (r). Conclusión: la medición pudo realizarse con exactitud a 0° y 30° grados, ya que presentan una correlación positiva entre las medidas. Sin embargo, a 0° y a 45° grados, la correlación fue débil mostrando poca asociación entre las variables.

Role of microRNAs 221/222 on Statin Induced Nitric Oxide Release in Human Endothelial Cells / Papel dos microRNAs 221/222 na Liberação de Óxido Nítrico Induzida por Estatinas em Células Endoteliais Humanas

Background: Nitric oxide (NO) has been largely associated with cardiovascular protection through improvement of endothelial function. Recently, new evidence about modulation of NO release by microRNAs (miRs) has been reported, which could be involved with statin-dependent pleiotropic effects, including anti-inflammatory properties related to vascular endothelium function. Objective: To evaluate the effects of cholesterol-lowering drugs including the inhibitors of cholesterol synthesis, atorvastatin and simvastatin, and the inhibitor of cholesterol absorption ezetimibe on NO release, NOS3 mRNA expression and miRs potentially involved in NO bioavailability. Methods: Human umbilical vein endothelial cells (HUVEC) were exposed to atorvastatin, simvastatin or ezetimibe (0 to 5.0 μM). Cells were submitted to total RNA extraction and relative quantification of NOS3 mRNA and miRs -221, -222 and -1303 by qPCR. NO release was measured in supernatants by ozone-chemiluminescence. Results: Both statins increased NO levels and NOS3 mRNA expression but no influence was observed for ezetimibe treatment. Atorvastatin, simvastatin and ezetimibe down-regulated the expression of miR-221, whereas miR-222 was reduced only after the atorvastatin treatment. The magnitude of the reduction of miR-221 and miR-222 after treatment with statins correlated with the increment in NOS3 mRNA levels. No influence was observed on the miR-1303 expression after treatments. Conclusion: NO release in endothelial cells is increased by statins but not by the inhibitor of cholesterol absorption, ezetimibe. Our results provide new evidence about the participation of regulatory miRs 221/222 on NO release induction mediated by statins. Although ezetimibe did not modulate NO levels, the down-regulation of miR-221 could involve potential effects on endothelial function. .

Fundamento: O óxido nítrico (NO) tem sido amplamente associado com proteção cardiovascular através de melhoria da função endotelial. Recentemente, novas evidências sobre a modulação do NO na liberação de microRNAs (miRs) têm sido relatadas, o que poderia estar envolvido com efeitos pleiotrópicos dependentes de estatinas, incluindo propriedades anti-inflamatórias relacionadas com a função do endotélio vascular. Objetivo: Avaliar os efeitos dos medicamentos redutores de colesterol, incluindo os inibidores da síntese de colesterol, atorvastatina e sinvastatina, e o inibidor da absorção de colesterol, ezetimiba, na liberação de NO, expressão do mRNA do NOS3 e miRs potencialmente envolvidos na biodisponibilidade do NO. Métodos: Células endoteliais da veia umbilical humana (HUVEC) foram expostas à atorvastatina, sinvastatina ou ezetimiba (0 a 5,0 μM). As células foram submetidas à extração do RNA total e quantificação relativa de mRNA do NOS3 e dos miRs-221,-222 e -1303 por qPCR. A liberação de NO foi medida em sobrenadantes por ozônio-quimioluminescência. Resultados: Ambas as estatinas aumentaram os níveis de NO e a expressão do mRNA do NOS3, mas nenhum efeito foi observado em relação ao tratamento com ezetimiba. A atorvastatina, sinvastatina e ezetimiba regularam negativamente a expressão do miR-221, enquanto que o miR-222 reduziu somente após o tratamento com atorvastatina. A magnitude da redução de miR-221 e miR-222 após tratamento com estatinas correlacionou com o incremento nos níveis de mRNA do NOS3. Nenhuma influência foi observada sobre a expressão do miR-1303 após os tratamentos. Conclusão: A liberação de NO pelas células endoteliais é aumentada por estatinas, mas não pelo inibidor da absorção de colesterol ezetimiba. Nossos resultados fornecem novas evidências sobre a participação dos miRs regulatórios 221/222 na liberação de NO mediada por estatinas. Embora a ezetimiba não tenha modulado os níveis de NO, a regulação negativa ...

Effects of catecholamines on volemic replacement with saline solution and the impact on heart rate variability in rabbits subjected to hemorrhage. A study by spectral analysis

PURPOSE: To verify the effects of different catecholamines on volemic expansion and on the autonomic nervous system in rabbits that were subjected to hemorrhage. METHODS: Twenty four rabbits subjected to hemorrhage (with a 25% loss of blood volume) and were randomly divided into four experimental groups: 1) HEMO Group underwent replacement with their own blood in an equal volume; 2) SS Group underwent replacement with saline solution (SS) in a volume that corresponded to three times the removed blood volume; 3) ISP Group underwent replacement with SS and isoprenaline; 4) FNL Group underwent replacement with SS and phenylephrine. Spectral Analysis of the heart rate and heart rate variability were performed from the recorded data. Hematocrit was measured throughout the experiment. RESULTS: Replacement with SS and an α- or β-agonist did not produce differences in the intravascular retention compared to replacement with SS alone. An analysis of HRV showed that the FNL group maintained the LF/HF ratio better than ISP and SS. CONCLUSIONS: No difference in vascular retention when α- or β- agonists were added to SS during post-hemorrhagic recovery. The animals in the FNL group maintained the integrity of the autonomic response within normal physiological standards during hemorrhagic stress. .

Intercostal and forearm muscle deoxygenation during respiratory fatigue in patients with heart failure: potential role of a respiratory muscle metaboreflex

The purpose of this study was to determine the effect of respiratory muscle fatigue on intercostal and forearm muscle perfusion and oxygenation in patients with heart failure. Five clinically stable heart failure patients with respiratory muscle weakness (age, 66±12 years; left ventricle ejection fraction, 34±3%) and nine matched healthy controls underwent a respiratory muscle fatigue protocol, breathing against a fixed resistance at 60% of their maximal inspiratory pressure for as long as they could sustain the predetermined inspiratory pressure. Intercostal and forearm muscle blood volume and oxygenation were continuously monitored by near-infrared spectroscopy with transducers placed on the seventh left intercostal space and the left forearm. Data were compared by two-way ANOVA and Bonferroni correction. Respiratory fatigue occurred at 5.1±1.3 min in heart failure patients and at 9.3±1.4 min in controls (P<0.05), but perceived effort, changes in heart rate, and in systolic blood pressure were similar between groups (P>0.05). Respiratory fatigue in heart failure reduced intercostal and forearm muscle blood volume (P<0.05) along with decreased tissue oxygenation both in intercostal (heart failure, -2.6±1.6%; controls, +1.6±0.5%; P<0.05) and in forearm muscles (heart failure, -4.5±0.5%; controls, +0.5±0.8%; P<0.05). These results suggest that respiratory fatigue in patients with heart failure causes an oxygen demand/delivery mismatch in respiratory muscles, probably leading to a reflex reduction in peripheral limb muscle perfusion, featuring a respiratory metaboreflex.

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. .