Agreement analysis of stroke volume and cardiac output measurement between a oscillometric device and transthoracic echocardiogram in normotensive individuals: a preliminary report

Abstract Introduction The evaluation of stroke volume (SV) is useful in research and patient care. To accomplish this, an ideal device should be noninvasive, continuous, reliable, and reproducible. The Mobil-O-Graph (MOG) is a noninvasive oscillometric matrix validated for measuring aortic and peripheral blood pressure, which through conversion algorithms can estimate hemodynamic parameters. Objectives To compare the MOG measurement of stroke volume, cardiac output, and cardiac index with the transthoracic echocardiogram (TTE). Methods Healthy volunteers aged 18 years or older were included. Two-dimensional TTEs were performed by a single operator. Subsequently, the measurement of noninvasive hemodynamics with MOG was performed with the operator blind to the results of the echocardiogram. Correlation analyses between stroke volume, cardiac output, and cardiac index parameters were performed. The degree of agreement between the methods was verified using the Bland-Altman method. Results A total of 38 volunteers were enrolled with a mean age of 27.6 ± 3.8 years; 21 (55%) were male The SV by TTE was 76.8 ± 19.5 mL and 75.7 ± 19.3 mL by MOG, Rho = 0.726, p< 0.0001. The CO by TTE was 5.04 ± 0.8 mL.min-1 and 5.1 ± 0.8 mL.min-1 by MOG Rho = 0.510, p= 0.001. Bland-Altman plots showed a good concordance between the two techniques. Conclusions Our study shows that the measurement of SV and CO by noninvasive hemodynamics with the MOG device offers a good concordance with the TTE with very few values beyond the confidence limits.

Comparative study between suprasternal and apical windows: a user-friendly cardiac output measurement for the anesthesiologist

Abstract Introduction Transthoracic echocardiography is a safe and readily available tool for noninvasive monitoring of Cardiac Output (CO). The use of the suprasternal window situated at the sternal notch can be an alternative approach for estimating blood flow. The present study aimed to compare two methods of CO calculation. We compared the descending aorta Velocity-Time Integral (VTI) measurement from the suprasternal window view with the standard technique to determine CO that uses VTI measurements from the LVOT (Left Ventricular Outflow Tract) view. We also aimed to find out whether after basic training a non-echocardiographer operator can obtain reproducible measurements of VTI using this approach. Methods In the first part of the study, 26 patients without known cardiovascular diseases were evaluated and VTI data were acquired from the suprasternal window by a non-echocardiographer and an echocardiographer. Next, 17 patients were evaluated by an echocardiographer only and VTI and CO measurements were obtained from suprasternal and apical windows. Data were analyzed using the Bland and Altman method (BA), correlation and regression. Results We found a strong correlation between measurements obtained by a non-expert and an expert echocardiographer and detected that an inexperienced trainee can acquire VTI measurements from the suprasternal window view. Regarding agreement between CO measurements, data obtained showed a positive correlation and the Bland and Altman analysis presented a total variation of 38.9%. Conclusion Regarding accuracy, it is likely that TTE (Transthoracic Echocardiogram) measurements of CO from the suprasternal window view are comparable to other minimally invasive techniques currently available. Due to its user-friendliness and low cost, it can be a convenient technique for obtaining perioperative hemodynamic measurements, even by inexperienced operators.

Hemodynamic effects of different fluid volumes for a fluid challenge in septic shock patients / 中华医学杂志(英文版)

BACKGROUND@#It is still unclear what the minimal infusion volume is to effectively predict fluid responsiveness. This study was designed to explore the minimal infusion volume to effectively predict fluid responsiveness in septic shock patients. Hemodynamic effects of fluid administration on arterial load were observed and added values of effective arterial elastance (Ea) in fluid resuscitation were assessed.@*METHODS@#Intensive care unit septic shock patients with indwelling pulmonary artery catheter (PAC) received five sequential intravenous boluses of 100 mL 4% gelatin. Cardiac output (CO) was measured with PAC before and after each bolus. Fluid responsiveness was defined as an increase in CO >10% after 500 mL fluid infusion.@*RESULTS@#Forty-seven patients were included and 35 (74.5%) patients were fluid responders. CO increasing >5.2% after a 200 mL fluid challenge (FC) provided an improved detection of fluid responsiveness, with a specificity of 80.0% and a sensitivity of 91.7%. The area under the ROC curve (AUC) was 0.93 (95% CI: 0.84-1.00, P  < 0.001). Fluid administration induced a decrease in Ea from 2.23 (1.46-2.78) mmHg/mL to 1.83 (1.34-2.44) mmHg/mL (P = 0.002), especially for fluid responders in whom arterial pressure did not increase. Notably, the baseline Ea was able to detect the fluid responsiveness with an AUC of 0.74 (95% CI: 0.59-0.86, P < 0.001), whereas Ea failed to predict the pressure response to FC with an AUC of 0.50 (95% CI: 0.33-0.67, P = 0.086).@*CONCLUSION@#In septic shock patients, a minimal volume of 200 mL 4% gelatin could reliably detect fluid responders. Fluid administration reduced Ea even when CO increased. The loss of arterial load might be the reason for patients who increased their CO without pressure responsiveness. Moreover, a high level of Ea before FC was able to predict fluid responsiveness rather than to detect the pressure responsiveness.@*TRIAL REGISTRATION@#ClinicalTrials.gov, NCT04515511.

Monitorizacion del gasto cardiaco con ecocardiografia transtoracica y cateter de Swan Ganz. Estudio comparativo en pacientes en ventilacion mecanica con presión positiva espiratoria final elevada / Cardiac output measured by transthoracic echocardiography and Swan-Ganz catheter. A comparative study in mechanically ventilated patients with high positive end-expiratory pressure

RESUMEN Objetivo: Comparar las medidas de gasto cardiaco por ecocardiografía transtorácica y por catéter arterial pulmonar en pacientes en ventilación mecánica con presión positiva al final de la espiración elevada. Evaluar el efecto de la insuficiencia tricúspide. Métodos: Se estudiaron 16 pacientes en ventilación mecánica. El gasto cardiaco se midió con el catéter arterial pulmonar y por ecocardiografía transtorácica. Las medidas se realizaron en diferentes niveles de presión positiva al final de la espiración (10cmH2O, 15cmH2O, y 20cmH2O). Se evalúo el efecto de la insuficiencia tricúspide sobre la medida de gasto cardiaco. Se estudió el coeficiente de correlación intraclase; el error medio y los límites de concordancia se estudiaron con el diagrama de Bland-Altman. Se calculó el porcentaje de error. Resultados: Se obtuvieron 44 pares de medidas de gasto cardiaco. Se obtuvo un coeficiente de correlación intraclase de 0,908, p < 0,001; el error medio fue 0,44L/min para valores de gasto cardíaco entre 5 a 13L/min. Los límites de concordancia se encontraron entre 3,25L/min y -2,37L/min. Con insuficiencia tricúspide el coeficiente de correlación intraclase fue 0,791, sin insuficiencia tricúspide el coeficiente de correlación intraclase fue 0,935. La presencia de insuficiencia tricúspide aumentó el porcentaje de error de 32 % a 52%. Conclusiones: En pacientes con presión positiva al final de la espiración elevada la medida de gasto cardiaco por ecocardiografía transtorácica es comparable con catéter arterial pulmonar. La presencia de insuficiencia tricúspide influye en el coeficiente de correlación intraclase. En pacientes con presión positiva al final de la espiración elevada, el uso de ecocardiografía transtorácica para medir gasto cardiaco es comparable con las medidas invasivas.

ABSTRACT Objective: To compare cardiac output measurements by transthoracic echocardiography and a pulmonary artery catheter in mechanically ventilated patients with high positive end-expiratory pressure. To evaluate the effect of tricuspid regurgitation. Methods: Sixteen mechanically ventilated patients were studied. Cardiac output was measured by pulmonary artery catheterization and transthoracic echocardiography. Measurements were performed at different levels of positive end-expiratory pressure (10cmH2O, 15cmH2O, and 20cmH2O). The effect of tricuspid regurgitation on cardiac output measurement was evaluated. The intraclass correlation coefficient was studied; the mean error and limits of agreement were studied with the Bland-Altman plot. The error rate was calculated. Results: Forty-four pairs of cardiac output measurements were obtained. An intraclass correlation coefficient of 0.908 was found (p < 0.001). The mean error was 0.44L/min for cardiac output values between 5 and 13L/min. The limits of agreement were 3.25L/min and -2.37L/min. With tricuspid insufficiency, the intraclass correlation coefficient was 0.791, and without tricuspid insufficiency, 0.935. Tricuspid insufficiency increased the error rate from 32% to 52%. Conclusions: In patients with high positive end-expiratory pressure, cardiac output measurement by transthoracic echocardiography is comparable to that with a pulmonary artery catheter. Tricuspid regurgitation influences the intraclass correlation coefficient. In patients with high positive end-expiratory pressure, the use of transthoracic echocardiography to measure cardiac output is comparable to invasive measures.

Test-Retest Reliability of Non-Invasive Cardiac Output Measurement during Exercise in Healthy Volunteers in Daily Clinical Routine / Confiabilidade Teste-Reteste de Medição Não-Invasiva de Débito Cardíaco durante Exercício em Voluntários Saudáveis sob Condições Clínicas de Rotina

Abstract Background: Thoracic bioreactance (TB), a noninvasive method for the measurement of cardiac output (CO), shows good test-retest reliability in healthy adults examined under research and resting conditions. Objective: In this study, we evaluate the test-retest reliability of CO and cardiac power (CPO) output assessment during exercise assessed by TB in healthy adults under routine clinical conditions. Methods: 25 test persons performed a symptom-limited graded cycling test in an outpatient office on two different days separated by one week. Cardiorespiratory (power output, VO2peak) and hemodynamic parameters (heart rate, stroke volume, CO, mean arterial pressure, CPO) were measured at rest and continuously under exercise using a spiroergometric system and bioreactance cardiograph (NICOM, Cheetah Medical). Results: After 8 participants were excluded due to measurement errors (outliers), there was no systematic bias in all parameters under all conditions (effect size: 0.2-0.6). We found that all noninvasively measured CO showed acceptable test-retest-reliability (intraclass correlation coefficient: 0.59-0.98; typical error: 0.3-1.8). Moreover, peak CPO showed better reliability (intraclass correlation coefficient: 0.80-0.85; effect size: 0.9-1.1) then the TB CO, thanks only to the superior reliability of MAP (intraclass correlation coefficient: 0.59-0.98; effect size: 0.3-1.8). Conclusion: Our findings preclude the clinical use of TB in healthy subject population when outliers are not identified.

Resumo Fundamento: A biorreatância torácica (BT), um método não invasivo destinado à medição do débito cardíaco (DC), mostra boa confiabilidade teste-reteste em adultos saudáveis examinados em condições de pesquisa e repouso. Objetivo: No presente estudo, avaliamos a confiabilidade teste-reteste da avaliação do DC e trabalho cardíaco (TC) durante exercício, avaliado por BT em adultos saudáveis sob condições clínicas de rotina. Métodos: 25 indivíduos realizaram teste ergométrico gradual sintoma-limitante em ambiente ambulatorial em dois dias diferentes, com intervalo de uma semana. Parâmetros cardiorrespiratórios (trabalho cardíaco, VO2máx) e hemodinâmicos (frequência cardíaca, volume sistólico, DC, pressão arterial média, TC) foram medidos em repouso e continuamente sob exercício utilizando sistema espiroergométrico e cardiógrafo de biorreatância (NICOM, Cheetah Medical). Resultados: Após 8 participantes terem sido excluídos devido a erros de medição (outliers), não houve viés sistemático em nenhum dos parâmetros em todas as condições (tamanho do efeito: 0,2-0,6). Observamos que todos os débitos cardíacos medidos de forma não invasiva apresentaram níveis aceitáveis de confiabilidade teste-reteste (coeficiente de correlação intraclasse: 0,59-0,98; erro típico: 0,3-1,8). Além disso, TC máximo apresentou melhor confiabilidade (coeficiente de correlação intraclasse: 0,80-0,85; tamanho do efeito: 0,9-1,1), seguido do DC pela BT, graças apenas à confiabilidade superior da PAM (coeficiente de correlação intraclasse: 0,59-0,98; tamanho do efeito: 0,3-1,8). Conclusão: Nossos achados impedem o uso clínico da BT em indivíduos saudáveis quando outliers não forem identificados.

La posición de Trendelenburg no cambia el gasto cardíaco en voluntarios sanos / Trendelenburg position does not change Cardiac output in healthy volunteers

BACKGROUND: The Trendelenburg position (TP) has been empirically used to increase preload and thus cardiac output (CO). Transthoracic echocardiogram (TTE) is a noninvasive technique that estimates CO. We aimed to describe if the TP can improve CO. MATERIALS AND METHODS: We conducted a descriptive study in healthy subjects (ASA I), with TTE measurements of CO and the End-Diastolic Volume of the Left Ventricle (EDVLV) in supine and after 5 minutes in TP. RESULTS: There showed no significant changes in blood pressure, heart rate and pulse oximetry in 0° and after 5 minutes in 45°. The mean CO without inclination was 4.2 l/min ± 0.6, tat is the same results after 5 minutes in PT (p > 0.6). The EDVLV was 95 ± 12 ml at 0° and 101 ± 15 ml after 5 minutes in PT (p > 0.8). CONCLUSION: Trendelenburg position doesn't improve CO or preload in healthy subjects.

INTRODUCCIÓN: Empíricamente se ha utilizado la posición de Trendelenburg (PT) para aumentar la precarga y posteriormente el gasto cardiaco (GC). La ecografía transtorácica (ETT) es una técnica no invasiva que puede estimar el GC. Realizamos un estudio descriptivo para evaluar si la PT afecta el CG. MATERIALES Y MÉTODOS: Examinamos pacientes ASA I, se hicieron mediciones del GC y del volumen de fin de diástole (VDFVI) en posición supina y luego de cinco minutos en PT. RESULTADOS: No se observaron cambios significativos en la presión arterial, frecuencia cardíaca y saturometría en los voluntarios a 0º y a 45º. El GC sin inclinación fue en promedio 4,2 l/min ± 0,6, el mismo resultado tras cinco minutos en PT, sin ser estadísticamente significativo (p > 0,6). El VDFVI a 0º fue en promedio 95 ± 12 ml y tras cinco minutos en PT 101 ± 15 ml, que tampoco alcanzó diferencia estadísticamente significativa (p > 0,8). CONCLUSIÓN: La posición de Trendelenburg no varía el gasto cardiaco ni la precarga en voluntarios sanos.

Uso de ecocardiografia junto ao leito para medir índices cardíaco e de resistência vascular sistêmica em pacientes pediátricos com choque séptico / The use of bedside echocardiography for measuring cardiac index and systemic vascular resistance in pediatric patients with septic shock

RESUMO Objetivo: Acompanhar o índice cardíaco e o índice de resistência vascular sistêmica até a ressuscitação. Métodos: Por meio de ecocardiografia junto ao leito, obteve-se um conjunto de parâmetros hemodinâmicos, inclusive débito cardíaco, volume sistólico, índice cardíaco, índice de resistência vascular sistêmica, integral velocidade-tempo, índice de desempenho miocárdico, tempo de reenchimento capilar e frequência cardíaca no momento zero após infusão de fluidos em bolo, e início e utilização de fármacos inotrópicos, com seguimento até 6 horas e 24 horas. Resultados: Incluíram-se 45 pacientes com choque séptico adquirido na comunidade. Os focos de infecção foram gastrenterite (24%), perfuração intestinal com necessidade de cirurgia emergencial (24%), pneumonia (20%), infecção do sistema nervoso central (22%) e infecção de tecidos moles (8%). Os isolados mais frequentes foram de Klebsiella e Enterobacter. Estimamos os fatores que afetaram o índice cardíaco: pressão venosa central elevada no momento zero (r = 0,33; p = 0,024) e persistência de frequência cardíaca elevada após 6 horas (r = 0,33; p = 0,03). O índice de resistência vascular sistêmica foi alto na maioria dos pacientes no momento zero e após 24 horas, e por ocasião da ressuscitação, afetando inversamente o índice cardíaco, assim como a integral velocidade-tempo (r = -0,416; -0,61; 0,55 e -0,295). O tempo de reenchimento capilar aumentado foi preditor clínico de valores baixos de integral velocidade-tempo após 24 horas (r = -0,4). O índice de mortalidade foi de 27%. Nos pacientes que não sobreviveram, observaram-se índices de resistência vascular sistêmica mais baixos e débitos cardíacos mais altos. Conclusão: O índice de resistência vascular sistêmica esteve persistentemente elevado em pacientes com choque frio, o que influenciou no índice de volume sistólico, no índice cardíaco e na integral velocidade-tempo. O uso de ecocardiografia para obtenção de mensurações hemodinâmicas é importante em pacientes pediátricos com choque séptico, para que se possam ajustar as doses de vasodilatadores e vasopressores, e obter os objetivos da ressuscitação em tempo apropriado.

ABSTRACT Objective: Follow-up of cardiac index and systemic vascular resistance index by bedside echocardiography until resuscitation. Methods: A set of hemodynamic parameters was obtained, including cardiac output, stroke volume, cardiac index, systemic vascular resistance index, velocity time integral, myocardial performance index, capillary refill time, and heart rate at 0 hours after fluid boluses before the start of inotropes, and followed up after 6 hours and 24 hours. Results: Included were 45 patients with community-acquired septic shock. Septic foci were gastroenteritis (24%), intestinal perforation requiring emergency surgery (24%), pneumonia (20%), central nervous system infection (22%) and soft tissue infection (8%). Klebsiella and Enterobacter were the most frequent isolates. We estimated the factors affecting the cardiac index: high central venous pressure at zero time (r = 0.33, p = 0.024) and persistently high heart rate at hour 6 (r = 0.33, p = 0.03). The systemic vascular resistance index was high in most patients at 0 and 24 hours and at the time of resuscitation and inversely affected the cardiac index as well as affecting the velocity time integral (r = -0.416, -0.61, 0.55 and -0.295). Prolonged capillary refill time was a clinical predictor of the low velocity time integral at 24 hours (r = -0.4). The mortality was 27%. Lower systemic vascular resistance index and higher cardiac output were observed in nonsurviving patients. Conclusion: There was a persistently high systemic vascular resistance index in cold shock patients that influenced the stroke volume index, cardiac index, and velocity time integral. The use of echocardiograms for hemodynamic measurements is important in pediatric septic shock patients to adjust dilators, and vasopressor doses and achieve resuscitation targets in a timely manner.

Medición de gasto cardíaco con ecocardiogafía transtorácica durante anestesia espinal en pacientes sanos / Measurement of cardiac expenditure with transtoracial echocardiography during spinal anesthesia in healthy patients

Introducción: La anestesia espinal produce cambios hemodinámicos como hipotensión (descrita hasta en un 30% de los pacientes) y bradicardia. La fisiología de estos cambios fue estudiada hace años en modelos animales y humanos experimentales. En la actualidad la ecocardiografia transtorácica (ETT) puede ser un monitor no invasivo útil y moderno para estudiar qué ocurre con el gasto cardíaco (GC) luego de un bloqueo subaracnoideo en la práctica clínica diaria. Objetivo : Evaluar el comportamiento del GC con el uso de ETT luego de la instalación de una anestesia espinal. Material y Método : En forma prospectiva se estudiaron pacientes ASA I propuestos para cirugía bajo anestesia espinal. El GC basal se estudió utilizando la ventana paraesternal izquierda donde se midió el diámetro del tracto de salida del ventrículo izquierdo y se le calculó su área. Luego desde la ventana apical en cinco cámaras se midió con Doppler continuo la integral de la velocidad máxima del tracto de salida (IVT). Al multiplicar IVT por su área se obtuvo el volumen de eyección (VE) que se multiplicó por la frecuencia cardíaca (FC), obteniéndose el GC. Luego se instaló la anestesia espinal utilizando una mezcla estandarizada con chirocaína al 0,5% y fentanyl 20 microgramos en un volumen entre 2,5 y 3 ml. El mismo examen ecocardiográfico para medir GC se realizó una vez comprobada la instalación del bloqueo espinal. Resultados : Se estudiaron 52 enfermos; en sólo 2 no hubo ventanas ecocardiográficas satisfactorias. La edad promedio fue de 44,8 ± 11 años. En todos los casos se realizó la cirugía con el bloqueo espinal. El nivel de bloqueo alcanzado fue T6 en un 36,36% de los casos y T4 en un 32,73%. Las variaciones de la presión arterial sistólica, diastólica y frecuencia cardíaca tuvieron una disminución estadísticamente significativa. No se observó una diferencia significativa en el GC previo y posterior a la anestesia espinal. La altura sensitiva máxima del bloqueo subaracnoideo tampoco se correlacionó con la disminución de la presión arterial media (PAM) ni con los parámetros ecocardiograficos. Conclusión : La anestesia espinal produjo disminución de los parámetros hemodinámicos. El uso de ecocardiografía transtorácica intraoperatoria permitió el estudio directo y real de la fisiología cardiovascular y demostrar que pese a la baja de la presión arterial y frecuencia cardíaca el GC tendió a mantenerse, probablemente por otros mecanismos de compensación como aumento de la contractilidad miocárdica y mejoría de la función diastólica. En el futuro la ETT puede ser una herramienta de estudio para evaluar qué ocurre con diferentes fármacos anestésicos y diferentes tipos de pacientes (obstétricas, cardióptas).

Background: Spinal anesthesia produces hemodynamic changes such as hypotension (described in up to 30% of patients) and bradycardia. The physiology of these changes was studied years ago in animal and experimental human models. At present, transthoracic echocardiography (TTE) can be a useful and modern noninvasive monitor to study what happens with cardiac output (CO) after a subarachnoid block in daily clinical practice. Objective : To evaluate the behavior of the CO with the use of TTE after the installation of a spinal anesthesia. Material and Method : We prospectively studied ASA I patients proposed for surgery under spinal anesthesia. The baseline CO was studied using the left parasternal window where the diameter of the left ventricular outflow tract was measured and its area was calculated. Then from the apical window in five chamber view the integral of the maximum velocity of the outflow tract (IVT) was measured with continuous Doppler. When IVT was multiplied by its area, the ejection volume (VE) was multiplied by heart rate (HR), obtaining the CO. Spinal anesthesia was then installed using a mixture standardized with 0.5% chirocaine and 20 micrograms fentanyl in a volume between 2.5 and 3 ml. The same echocardiographic examination was done once the installation of the spinal block was verified. Results : We studied 52 patients, in only 2 there were no satisfactory echocardiographic windows. The average age was 44.8 ± 11 years. In all cases, surgery was performed with the spinal block. The level of blockade reached was T6 in 36.36% of the cases and T4 in 32.73%. The variations of the systolic, diastolic and heart rate had a statistically significant decrease. No significant difference was observed in the CO before and after spinal anesthesia. The maximum sensory height of the subarachnoid block did not correlate with the decrease in MAP or echocardiographic parameters. Conclusion : Spinal anesthesia produced decreased hemodynamic parameters. The use of intraoperative transthoracic echocardiography allowed the direct and real study of cardiovascular physiology and showed that despite the drop in blood pressure and heart rate, the CO tended to remain, probably due to other compensation mechanisms such as increased myocardial contractility and improvement of diastolic function. In the future, TTE can be a study tool to evaluate what happens with different anesthetic drugs and different types of patients (obstetric, cardiopathic).

Disminución de la presión venosa central: efecto sobre el gasto cardíaco / Reduction of central venous pressure: effect on cardiac output

Introducción: La disminución de la presión venosa central (PVC) a menos de 5mmHg ha sido recomendada para disminuir el sangrado durante la cirugía hepática. No se conoce el efecto de esto en el llenado ventricular e índice cardíaco (IC). Objetivo: Medir el efecto en el volumen de fin de diástole del ventrículo izquierdo indexado (VFDVII) e IC de la disminución a 3-4mmHg de la PVC. Método: Se estudiaron pacientes sometidos a cirugía general en los cuales se monitorizó presión arterial directa, PVC, y ecocardiografía transesofágica (ETE). Posterior a la inducción anestésica, y después de 5min de estabilidad hemodinámica, se midieron VFDVII e IC, los cuales se repitieron 5 min después de disminuir la PVC a 3-4 mmHg. Resultados: Se estudiaron 32 pacientes; 12 cumplían criterios de disfunción diastólica (DD). Los valores basales y posteriores a la reducción de la PVC de VFDVII e IC fueron respectivamente 49,4 ± 13 y 40,1 ±13 ml/m², y 2,8 ± 0,56 y 2,5 ± 0,7 l/m² (ambos p < 0,01). Todas las variaciones fueron mayores en los pacientes con DD. Conclusiones: La disminución de la PVC a los niveles recomendados para disminuir el sangrado produce una moderada pero significativa reducción del IC. Esto debe ser considerado en pacientes con condiciones que pudieran hacer más importante el efecto de la disminución de la PVC.

Introduction: The reduction of central venous pressure (CVP) below 5mmHg has been recommended to decrease bleeding during hepatic surgery. The effect of this practice on cardiac function has not been quantified. Objective: To measure the repercussion of the decrease of CVP on left ventricular end diastolic volume (LVEDV) and cardiac index (CI). Method: Patients undergoing general anaesthesia for major surgery were studied. Monitoring included direct arterial pressure, CVP, and transesophageal echocardiography (TEE). During a stable period of anaesthesia, all of these parameters were measured before and after lowering CVP to 3-4mmHg. Results: Thirty-two patients were studied. Twelve patients met TEE diagnostic criteria for diastolic dysfunction (DD). Basal and post CVP reduction values of LVEDVI and CI were 49.4 ± 13 and 40.1 ±13ml/m², 2.8±0.56 and 2.5±0.7l/m² respectively (both P< .01). All these variations were greater in patients with DD. Conclusions: Reduction of CVP produced a moderate but significant decrease in LVEDV and CI This should be considered in patients with conditions that may increase the effect of decreasing the CVP.

Effect of rhubarb on extravascular lung water in patients with acute respiratory distress syndrome

Summary Objective: The aim of this study was to evaluate the effect of rhubarb on extravascular lung water (EVLW) in patients with acute respiratory distress syndrome (ARDS). Method: A total of 80 patients with ARDS were randomly divided into a treatment group (40 cases) and control group (40 cases). Patients in the treatment group received rhubarb (30.0 g/d) and patients in the control group received conventional therapy for seven consecutive days. Extravascular lung water index (EVLWI) and pulmonary vascular permeability index (PVPI) were determined using pulse contour cardiac output (PiCCO) technology, and the oxygenation index was measured by blood gas analysis at baseline and on days 3, 5 and 7 after treatment. Results: The oxygenation index was higher and the levels of EVLWI and PVPI were lower after treatment in the two groups; however, these indexes showed significant differences on the 5th and 7th days after rhubarb treatment compared with the results in the control group (p<0.05). Conclusion: Rhubarb can decrease EVLWI and PVPI, and improve oxygenation in patients with ARDS.

Experimental validation of a cardiac simulator for in vitro evaluation of prosthetic heart valves

Abstract Objective: This work describes the experimental validation of a cardiac simulator for three heart rates (60, 80 and 100 beats per minute), under physiological conditions, as a suitable environment for prosthetic heart valves testing in the mitral or aortic position. Methods: In the experiment, an aortic bileaflet mechanical valve and a mitral bioprosthesis were employed in the left ventricular model. A test fluid of 47.6% by volume of glycerin solution in water at 36.5ºC was used as blood analogue fluid. A supervisory control and data acquisition system implemented previously in LabVIEW was applied to induce the ventricular operation and to acquire the ventricular signals. The parameters of the left ventricular model operation were based on in vivo and in vitro data. The waves of ventricular and systemic pressures, aortic flow, stroke volume, among others, were acquired while manual adjustments in the arterial impedance model were also established. Results: The acquired waves showed good results concerning some in vivo data and requirements from the ISO 5840 standard. Conclusion: The experimental validation was performed, allowing, in future studies, characterizing the hydrodynamic performance of prosthetic heart valves.

Fatores associados à regulação da pressão parcial de oxigênio e da pressão parcial de gás carbônico durante suporte respiratório com oxigenação por membrana extracorpórea: dados de um modelo em suínos / Factors associated with blood oxygen partial pressure and carbon dioxide partial pressure regulation during respiratory extracorporeal membrane oxygenation support: data from a swine model

RESUMO Objetivo: Explorar os fatores associados aos níveis sanguíneos da pressão parcial de oxigênio e da pressão parcial de gás carbônico. Métodos: Os fatores associados com a regulação do oxigênio e de gás carbônico foram investigados em um modelo com porcos em apneia com suporte de oxigenação por membrana extracorpórea venovenosa. Foi testada uma sequência predefinida de fluxos de sangue e gás. Resultados: A oxigenação associou-se principalmente com o fluxo da oxigenação por membrana extracorpórea (coeficiente beta = 0,036mmHg/mL/minuto), débito cardíaco (coeficiente beta = -11,970mmHg/L/minuto) e shunt pulmonar (coeficiente beta = -0,232mmHg/%). As mensurações iniciais da pressão parcial de oxigênio e da pressão parcial de gás carbônico também se associaram com oxigenação, com coeficientes beta de 0,160 e 0,442mmHg/mmHg, respectivamente. A pressão parcial de gás carbônico se associou com débito cardíaco (coeficiente beta = 3,578mmHg/L/minuto), fluxo de gás (coeficiente beta = -2,635mmHg/L/minuto), temperatura (coeficiente beta = 4,514mmHg/°C), pH inicial (coeficiente beta = -66,065mmHg/0,01 unidade) e hemoglobina (coeficiente beta = 6,635mmHg/g/dL). Conclusão: Elevações nos fluxos de sangue de gás em um modelo de oxigenação por membrana extracorpórea venovenosa durante apneia resultaram em aumento da pressão parcial de oxigênio e redução da pressão parcial de gás carbônico, respectivamente. Ainda, sem a possibilidade de uma inferência causal, a pressão parcial de oxigênio associou-se negativamente com o shunt pulmonar e o débito cardíaco, e a pressão parcial de gás carbônico teve associação positiva com o débito cardíaco, temperatura central e hemoglobina inicial.

ABSTRACT Objective: The aim of this study was to explore the factors associated with blood oxygen partial pressure and carbon dioxide partial pressure. Methods: The factors associated with oxygen - and carbon dioxide regulation were investigated in an apneic pig model under veno-venous extracorporeal membrane oxygenation support. A predefined sequence of blood and sweep flows was tested. Results: Oxygenation was mainly associated with extracorporeal membrane oxygenation blood flow (beta coefficient = 0.036mmHg/mL/min), cardiac output (beta coefficient = -11.970mmHg/L/min) and pulmonary shunting (beta coefficient = -0.232mmHg/%). Furthermore, the initial oxygen partial pressure and carbon dioxide partial pressure measurements were also associated with oxygenation, with beta coefficients of 0.160 and 0.442mmHg/mmHg, respectively. Carbon dioxide partial pressure was associated with cardiac output (beta coefficient = 3.578mmHg/L/min), sweep gas flow (beta coefficient = -2.635mmHg/L/min), temperature (beta coefficient = 4.514mmHg/ºC), initial pH (beta coefficient = -66.065mmHg/0.01 unit) and hemoglobin (beta coefficient = 6.635mmHg/g/dL). Conclusion: In conclusion, elevations in blood and sweep gas flows in an apneic veno-venous extracorporeal membrane oxygenation model resulted in an increase in oxygen partial pressure and a reduction in carbon dioxide partial pressure 2, respectively. Furthermore, without the possibility of causal inference, oxygen partial pressure was negatively associated with pulmonary shunting and cardiac output, and carbon dioxide partial pressure was positively associated with cardiac output, core temperature and initial hemoglobin.

Produção científica da Enfermagem sobre promoção de saúde, condição crônica e envelhecimento / Producción científica de Enfermería de promoción de la salud, condición crónica y envejecimiento / Nursing scientific production on health promotion, chronic condition, and aging

RESUMOObjetivo:caracterizar a produção científica dos Programas de Pós-Graduação em Enfermagem do Brasil, sobre promoção da saúde com enfoque nas pessoas idosas em condição crônica, no período de 2006 a 2010.Método:pesquisa integrativa, realizada através da busca de dissertações e teses da base de dados do Centro de Estudos e Pesquisas em Enfermagem da Associação Brasileira de Enfermagem, publicados no período de 2006 a 2010, que focassem a promoção de saúde de idosos em condição crônica.Resultados:emergiram cinco categorias temáticas: "Convívio com a doença"; "Tecnologias de cuidado"; "Potencialidades para o autocuidado" "Dimensão psicoespiritual" e "Família cuidadora".Conclusão:pôde-se identificar a assistência de enfermagem como elemento fundamental para promover a saúde do indivíduo idoso e torná-lo mais independente de cuidados para conviver com suas limitações ou incapacidades, mesmo acometido por doenças crônicas.

RESUMENObjetivo:caracterizar la producción científica de la Postgraduate Nursing Brasil, en la promoción de la salud con especial atención a las personas mayores con enfermedades crónicas en el período 2006-2010.Método:la investigación integral realizada mediante la búsqueda de disertaciones y tesis en la base de datos del Centro de Estudios e Investigación en Enfermería Asociación Brasileña de Enfermería, publicada en el período 2006-2010, que se centrará en la promoción de la salud para las personas mayores con enfermedades crónicas.Resultados:cinco temas emergieron: "La convivencia con la enfermedad", "cuidado Technologies", "potencial para el propio cuidado" "dimensión psico-espiritual" y "cuidador familiar".Conclusión:se pudo identificar el cuidado de enfermería como un elemento clave para promover la salud de las personas mayores y que sea una atención más independiente que vivir con limitaciones o incapacidades, aún afectados por enfermedades crónicas.

ABSTRACTObjective:to characterize the scientific production of Postgraduate Programs Nursing in Brazil on health promotion with a focus on elderly people with chronic conditions in the period from 2006 to 2010.Method:integrative research developed by searching for dissertations and theses in the database of the Center for Nursing Studies and Research of the Brazilian Nursing Association published in the period from 2006 to 2010 and which focused on health promotion for elderly people with chronic conditions.Results:five themes emerged: "Living with the disease"; "Technologies of care", "Potential for self-care" "Psycho-spiritual dimension", and "Family caregiver".Conclusion:it was possible to identify nursing care as a key element to promote the health of elderly people and make them more independent in their care so as to live with their limitations or disabilities, even when affected by chronic diseases.

Efeito do treinamento resistido com diferentes intensidades na pressão arterial em hipertensos / Effect of Resistance Training with Different intensities on blood pressure in hypertensive patients

Fundamentos: O efeito do treinamento resistido (TR) no comportamento da pressão arterial (PA), da frequência cardíaca (FC) e do duplo-produto (DP) está fortemente relacionado às características do exercício e apresenta-se inconsistente ao público hipertenso.Objetivos: Comparar a resposta cardiovascular aguda e tardia em sessões de 50% e 75% de uma repetição máxima estimada em hipertensos grau 1. Métodos: Analisou-se no período de 24 horas a pressão arterial sistólica (PAS) e diastólica (PAD) em 14 homens hipertensos leves, treinados (GT) e não treinados (GNT), submetidos a protocolos de 75% e 50% de uma repetição máxima estimada. Concomitantemente, verificou-se o nível de estresse cardiovascular em oito exercícios nas duas intensidades citadas. Resultados: No GT a variável PAS apresentou diferença entre o protocolo de menor intensidade em relação aos demais, 50% com controle (p=0,028) e 50% com 75% (p=0,022); a PAD diferenciou-se apenas nos protocolos de 50% com controle (p=0,024). No GNT a diferença ocorreu em todos os protocolos, tanto na PAS [50% e controle (p=<0,0001); 75% e controle (p=0,039); e 50% e 75% (p=0,001)] quanto na PAD [50% e controle (p=0,002); 75% e controle (p=0,002); e 50% e 75%(p=0,002)]. No estresse cardiovascular, os exercícios seated row e leg press no GT e os exercícios high row, leg curl e abdominal crunch no GNT mostraram diferenças em ambos os protocolos. Conclusão: Percebe-se segurança no TR em hipertensos leves. Ficou evidente que o protocolo de menor intensidade foi mais eficiente na promoção da hipotensão pós-exercício.

Background: The effect of resistance training (RT) on the behavior of blood pressure (BP), heart rate (HR) and double product (DP) is strongly related to the characteristics of exercise and is inconsistent with hypertensive individuals. Objectives: To compare the acute and late cardiovascular response in sessions of 50% and 75% of maximum estimated repetition in grade-1 hypertensive individuals. Methods: For 24 hours, the study analyzed systolic blood pressure (SBP) and diastolic blood pressure (DBP) in 14 mild hypertensive men, trained (TG) and untrained (UG), under protocols of 75% and 50% on maximum estimated repetition. The level of cardiovascular stress in eight exercises for the two intensities mentioned was concomitantly observed. Results: In the TG, the variable SBP showed differences between the protocol of lower intensity compared to the other, 50% with control (p=0.028) and 50% to 75% (p=0.022), and DBP differed only in the protocols of 50% with control (p=0.024). In the UG, the difference occurred in all protocols, as well in SBP [50% and control (p=<0.0001); 75% and control (p=0.039); and 50% and 75% (p=0.001)] as in DBP [50% and control (p=0.002); 75% and control (p=0.002); and 50% and 75% (p=0.002)]. On cardiovascular stress, the exercises seated row, leg press in the TG and high row, leg curl and abdominal crunch in the UG differed in both protocols. Conclusion: The results indicate safety in RT in mild hypertension men. It became evident that the lower intensity protocol showed higher efficiency in promoting post-exercise hypotension.

Hemodynamic, ventilatory and gasometric evaluation of an experimental bronchopleural fistula

PURPOSE: To investigate the hemodynamic and ventilatory changes associated with the creation of an experimental bronchopleural fistula (BPF) treated by mechanical ventilation and thoracic drainage with or without a water seal. METHODS : Six large white pigs weighing 25 kg each which, after general anesthesia, underwent endotracheal intubation (6mm), and mechanically ventilation. Through a left thoracotomy, a resection of the lingula was performed in order to create a BPF with an output exceeding 50% of the inspired volume. The chest cavity was closed and drained into the water sealed system for initial observation of the high output BPF. RESULTS: Significant reduction in BPF output and PaCO2 was related after insertion of a water-sealed thoracic drain, p< 0.05. CONCLUSION: Insertion of a water-sealed thoracic drain resulted in reduction in bronchopleural fistula output and better CO2 clearance without any drop in cardiac output or significant changes in mean arterial pressure. .

Efficacy of Goal-Directed Therapy Using Bioreactance Cardiac Output Monitoring after Valvular Heart Surgery

PURPOSE: We compared the efficacy of postoperative hemodynamic goal-directed therapy (GDT) using a pulmonary artery catheter (PAC) and bioreactance-based noninvasive cardiac output monitoring (NICOM) in patients with atrial fibrillation undergoing valvular heart surgery. MATERIALS AND METHODS: Fifty eight patients were randomized into two groups of GDT with common goals to maintain a mean arterial pressure of 60-80 mm Hg and cardiac index > or =2 L/min/m2: the PAC group (n=29), based on pulmonary capillary wedge pressure, and the NICOM group (n=29), based on changes in stroke volume index after passive leg raising. The primary efficacy variable was length of hospital stay. Secondary efficacy variables included resource utilization including vasopressor and inotropic requirement, fluid balance, and major morbidity endpoints. RESULTS: Patient characteristics and operative data were similar between the groups, except that significantly more patients underwent double valve replacement in the NICOM group. The lengths of hospital stay were not different between the two groups (12.2+/-4.8 days vs. 10.8+/-4.0 days, p=0.239). Numbers of patients requiring epinephrine (5 vs. 0, p=0.019) and ventilator care >24 h (6 vs. 1, p=0.044) were significantly higher in the PAC group. The PAC group also required significantly larger amounts of colloid (1652+/-519 mL vs. 11430+/-463 mL, p=0.004). CONCLUSION: NICOM-based postoperative hemodynamic GDT showed promising results in patients with atrial fibrillation undergoing valvular heart surgery in terms of resource utilization.

Comparison between continuous non-invasive estimated cardiac output by pulse wave transit time and thermodilution method.

Aims and Objectives: Cardiac output (CO) measurement is essential for many therapeutic decisions in anesthesia and critical care. Most available non‑invasive CO measuring methods have an invasive component. We investigate “pulse wave transit time” (estimated continuous cardiac output [esCCO]) a method of CO measurement that has no invasive component to its use. Materials and Methods: After institutional ethical committee approval, 14 adult (21–85 years) patients undergoing surgery and requiring pulmonary artery catheter (PAC) for measuring CO, were included. Postoperatively CO readings were taken simultaneously with thermodilution (TD) via PAC and esCCO, whenever a change in CO was expected due to therapeutic interventions. Both monitoring methods were continued until patients’ discharge from the Intensive Care Unit and observer recording values using TD method was blinded to values measured by esCCO system. Results: Three hundred and one readings were obtained simultaneously from both methods. Correlation and concordance between the two methods was derived using Bland‑Altman analysis. Measured values showed significant correlation between esCCO and TD (r = 0.6, P < 0.001, 95% confidence limits of 0.51-0.68). Mean and (standard deviation) for bias and precision were 0.13 (2.27) L/min and 6.56 (2.19) L/min, respectively. The 95% confidence interval for bias was ‑ 4.32 to 4.58 L/min and for precision 2.27 to10.85 L/min. Conclusions: Although, esCCO is the only true non‑invasive continuous CO monitor available and even though its values change proportionately to TD method (gold standard) with the present degree of error its utility for clinical/therapeutic decision‑making is questionable.

Influence of population and exercise protocol characteristics on hemodynamic determinants of post-aerobic exercise hypotension

Due to differences in study populations and protocols, the hemodynamic determinants of post-aerobic exercise hypotension (PAEH) are controversial. This review analyzed the factors that might influence PAEH hemodynamic determinants, through a search on PubMed using the following key words: “postexercise” or “post-exercise” combined with “hypotension”, “blood pressure”, “cardiac output”, and “peripheral vascular resistance”, and “aerobic exercise” combined only with “blood pressure”. Forty-seven studies were selected, and the following characteristics were analyzed: age, gender, training status, body mass index status, blood pressure status, exercise intensity, duration and mode (continuous or interval), time of day, and recovery position. Data analysis showed that 1) most postexercise hypotension cases are due to a reduction in systemic vascular resistance; 2) age, body mass index, and blood pressure status influence postexercise hemodynamics, favoring cardiac output decrease in elderly, overweight, and hypertensive subjects; 3) gender and training status do not have an isolated influence; 4) exercise duration, intensity, and mode also do not affect postexercise hemodynamics; 5) time of day might have an influence, but more data are needed; and 6) recovery in the supine position facilitates systemic vascular resistance decrease. In conclusion, many factors may influence postexercise hypotension hemodynamics, and future studies should directly address these specific influences because different combinations may explain the observed variability in postexercise hemodynamic studies.

Severe hypoxemia during veno-venous extracorporeal membrane oxygenation: exploring the limits of extracorporeal respiratory support

OBJECTIVE: Veno-venous extracorporeal oxygenation for respiratory support has emerged as a rescue alternative for patients with hypoxemia. However, in some patients with more severe lung injury, extracorporeal support fails to restore arterial oxygenation. Based on four clinical vignettes, the aims of this article were to describe the pathophysiology of this concerning problem and to discuss possibilities for hypoxemia resolution. METHODS: Considering the main reasons and rationale for hypoxemia during veno-venous extracorporeal membrane oxygenation, some possible bedside solutions must be considered: 1) optimization of extracorporeal membrane oxygenation blood flow; 2) identification of recirculation and cannula repositioning if necessary; 3) optimization of residual lung function and consideration of blood transfusion; 4) diagnosis of oxygenator dysfunction and consideration of its replacement; and finally 5) optimization of the ratio of extracorporeal membrane oxygenation blood flow to cardiac output, based on the reduction of cardiac output. CONCLUSION: Therefore, based on the pathophysiology of hypoxemia during veno-venous extracorporeal oxygenation support, we propose a stepwise approach to help guide specific interventions. .