Avaliação ecocardiográfica do paciente com choque circulatório: uma abordagem contemporânea / Echocardiographic evaluation of a patient in circulatory shock: a contemporary approach

O choque circulatório é caracterizado por um estado de ineficiência da oferta de oxigênio tecidual e disfunção múltipla de órgãos. Necessita de diagnóstico e terapias rápidas e assertivas para redução de sua alta letalidade. O ecocardiograma já se estabeleceu como método fundamental no manejo do paciente com choque circulatório. Auxilia de forma crucial no diagnóstico etiológico, prognóstico, monitorização hemodinâmica e estimativa volêmica desses pacientes, tendo como potenciais vantagens a portabilidade, ausência de contraste ou radiação, baixo custo e avaliação em tempo real e de forma seriada. Em ambiente de UTI, demonstra alta correlação com formas invasivas (cateter de artéria pulmonar) e minimamente invasivas (termodiluição transpulmonar) de monitorização hemodinâmica. Atualmente, outras técnicas, como ultrassom pulmonar e VExUS score, têm se agregado à avaliação ecocardiográfica, tornando o método mais abrangente e acurado. Essas técnicas acrescentam dados relevantes na estimativa da volemia do paciente crítico, influenciando na decisão probabilística de fluidoresponsividade e agregando informações no raciocínio diagnóstico das causas do choque, otimizando o prognóstico desses pacientes. O point of care ultrasound (POCUS) tem como objetivo tornar mais acessível, ao médico não especialista em radiologia, habilidades para se obter informações a beira leito, por meio do ultrassom, que o ajudem na tomada de decisões. Esse artigo aborda as diversas aplicabilidades do ecocardiograma em pacientes com choque circulatório, incluindo avaliação prognóstica e diagnóstico etiológico por meio dos parâmetros encontrados nas principais causas de choque, além da monitorização hemodinâmica, avaliação de fluido-responsividade e utilização prática do ultrassom pulmonar.(AU)

Circulatory shock is characterized by a state of inefficient tissue oxygen supply and multiple organ dysfunction. Patients with circulatory shock require fast and assertive diagnosis and therapies to reduce its high lethality. Echocardiography has already been established as a fundamental method in managing patients with circulatory shock. It provides crucial assistance in etiological diagnosis, prognosis, hemodynamic monitoring, and volume estimation in these patients; its potential advantages include portability, absence of contrast or radiation, low cost, and real-time serial assessment. In the intensive care unit setting, it demonstrates a high correlation with invasive (pulmonary artery catheter) and minimally invasive (transpulmonary thermodilution) forms of hemodynamic monitoring. Currently, other techniques, such as pulmonary ultrasound and VExUS score, have been added to echocardiographic assessment, making the method more comprehensive and accurate. These techniques add relevant data to blood volume estimation in critical patients, influencing the probabilistic decision of fluid responsiveness and providing additional information in the diagnostic reasoning of the causes of shock, thus optimizing these patients' prognosis. Point of care ultrasound (POCUS) aims to make abilities to obtain information at the bedside more accessible to physicians who are not specialists in radiology, by means of ultrasound, which assists them in decision-making. This article addresses the diverse applications of echocardiography in patients with circulatory shock, including prognostic evaluation and etiological diagnosis by means of the parameters found in the main causes of shock, in addition to hemodynamic monitoring, evaluation of fluid responsiveness, and practical use of pulmonary ultrasound.(AU)

Evaluación de la concordancia entre las variaciones de la velocidad pico aórtico y velocidad pico carotídeo con la ventilación mecánica en una población pediátrica sometida a cirugía electiva bajo anestesia general / Evaluation of the agreement between variations in aortic peak velocity and carotid peak velocity with mechanical ventilation in a pediatric population undergoing elective surgery under general anesthesia

Introducción. La variación de la velocidad máxima aórtica con la ventilación mecánica (ΔVpeakAo) ha demostrado ser el mejor predictor de respuesta a volumen en pediatría. Existe evidencia en adultos de que la variación de velocidad máxima de flujo carotídeo (ΔVpeakCar) es predictor de respuesta a fluidos. Al momento es escasa la información sobre este índice en pediatría. Su beneficio se basa en la no-invasividad, y que para su medición no es necesaria la ecocardiografía ni el acceso al tórax del paciente. Objetivo. El objetivo general de este trabajo fue estudiar la correlación y la concordancia de ΔVpeakCar con ΔVpeakAo en una población pediátrica bajo ventilación mecánica. Metodología. Se incluyeron pacientes de 0 a 12 años. Se registraron flujos aórtico y carotídeos máximos y mínimos y se calculó ΔVpeakCar y ΔVpeakAo. Para analizar correlación y concordancia entre las variables se utilizó el test de Pearson, análisis de Bland-Altman y análisis de los 4-cuadrantes. Resultados. Se estudiaron 58 pacientes, 13 lactantes (menores 12 meses), 21 preescolares (12-60 meses) y 24 escolares (mayores a 60 meses). Se observó una correlación significativa entre ΔVpeakAo y ΔVpeakCar (r=0,85; p<0,05) con un coeficiente de determinación de r2=0,72. El análisis de Bland-Altman mostró un sesgo del 0,15% (IC95%, -0.7-1.0) con un límite de concordancia del -6,1 a 6,2%. La concordancia fue 85%, con un sesgo angular de 4,5°±31°. El análisis por subgrupos mostró un r2 de 0.89 en escolares, 0.56 en preescolares y 0.45 en lactantes. La concordancia fue de 100% en escolares, 95% en prescolares y 93% en lactantes. Discusión y conclusiones. El registro de ΔVpeakCar fue viable. Al analizar la capacidad de ΔVpeakCar de sustituir a ΔVpeakAo en el total de la muestra, no es buena La correlación y concordancia son mejores en escolares. Es necesario continuar estudiando este nuevo índice.

Introduction. The variation in maximum aortic velocity with mechanical ventilation (ΔVpeakAo) has proven to be the most effective predictor of fluid response in pediatrics. While there is evidence in adults that the variation in maximum carotid flow velocity (ΔVpeakCar) predicts fluid response, information on this index in pediatrics remains limited. Its advantage lies in its non-invasive nature, eliminating the need for echocardiography or thoracic access for recording. Objective. This study aims to examine the correlation and concordance between ΔVpeakCar and ΔVpeakAo in a pediatric population. Methodology. The study included patients aged 0 to 12 years. Maximum and minimum aortic and carotid flows were recorded, and ΔVpeakCar and ΔVpeakAo were calculated. Correlation and agreement between variables were analyzed using the Pearson test, Bland Altman analysis, and 4-quadrant analysis. Results. A total of 58 patients were studied, comprising 13 infants (under 12 months), 21 preschoolers (12-60 months), and 24 school-aged children (over 60 months). A significant correlation was observed between ΔVpeakAo and ΔVpeakCar (r=0.85; p<0.05) with a coefficient of determination, r²=0.72. The Bland-Altman analysis revealed a bias of 0.15% (95% CI, -0.7-1.0) with an agreement limit of -6.1% to 6.2%. The concordance rate was 85%, with an angular bias of 4.5°±31°. Subgroup analysis showed r² values of 0.89 in school-aged children, 0.56 in preschoolers, and 0.45 in infants. Concordance rates were 100% in school-aged children, 95% in preschoolers, and 93% in infants. Discussion and Conclusions. The measurement of ΔVpeakCar proved feasible. However, when considering its ability to replace ΔVpeakAo, the results are suboptimal. Correlation and concordance are stronger in school-aged children. Further investigation into this new index is warranted.

Predictive value of carotid ultrasound in combination with passive leg raising on fluid responsiveness in critically ill patients / 中华危重病急救医学

Objective:To investigate the value of monitor carotid velocity time integral (VTI) and corrected flow time (FTc) by bedside ultrasound before and after passive leg raising (PLR) in predicting fluid responsiveness in critically ill patients.Methods:A prospective observational study was conducted. Fifty patients with critical illness admitted to the First People's Hospital of Fuyang Hangzhou from January 2020 to March 2021 were enrolled. The clinical data including the gender, age, body mass index (BMI), acute physiology and chronic health evaluationⅡ(APACHEⅡ) score, and the duration of mechanical ventilation were recorded. The changes of carotid VTI and FTc were measured by bedside ultrasound, and the values of heart rate, mean arterial pressure (MAP), central venous pressure (CVP), stroke volume index (SVI), and intrathoracic blood volume index (ITBVI) were measured by pulse indicated continuous cardiac output (PiCCO) monitor before and after PLR in all patients. According to the changes of SVI before and after PLR, the patients were divided into fluid responsiveness positive group with the change rate of SVI≥15% and fluid responsiveness negative group with the change rate of SVI < 15%. The differences in the values of VTI, FTc, CVP, and ITBVI obtained before and after PLR (ΔVTI, ΔFTc, ΔCVP and ΔITBVI) were calculated and then compared between the two groups. The predictive values of these indicators on fluid responsiveness in critically ill patients were analyzed by receiver operator characteristic curve (ROC curve), and their relationship with the difference in SVI (ΔSVI) obtained before and after PLR was evaluated by Pearson correlation analysis.Results:Fifty patients were all enrolled in this study, in which 27 patients were fluid response and 23 patients were fluid nonresponse. Basic clinical data were not different between the two groups. The values of ΔVTI, ΔFTc, ΔCVP, and ΔITBVI in fluid response were all significantly higher than those in fluid nonresponse [ΔVTI (cm): 2.07±1.16 vs. 0.67±0.86, ΔFTc (ms): 4.00±6.10 vs. 0.01±2.26, ΔCVP (cmH 2O, 1 cmH 2O = 0.098 kPa): 1.67±1.14 vs. 1.00±1.17, ΔITBVI (mL/m 2): 98±69 vs. 48±70, all P < 0.05]. ROC curve analysis showed that ΔVTI, ΔFTc, ΔCVP and ΔITBVI were all positive for predicting fluid responsiveness, their area under ROC curve (AUC) and 95% confidence interval (95% CI) were 0.870 (0.769-0.972), 0.694 (0.547-0.841), 0.684 (0.535-0.832) and 0.709 (0.564-0.855), respectively. When using ΔVTI 0.92 cm, ΔFTc 1.45 ms, ΔCVP 1.50 cmH 2O and ΔITBVI 44.50 mL/m 2 as the threshold values, the sensitivities were 96.3%, 63.0%, 44.4% and 81.5%, and the specificities were 65.2%, 78.3%, 82.6% and 56.5%, respectively, in which the predictive value of ΔVTI was the largest. Pearson correlation analysis indicated that ΔVTI, ΔFTc, ΔCVP, and ΔITBVI were positively associated with ΔSVI ( r values were 0.971, 0.334, 0.440, 0.650, P values were 0.000, 0.018, 0.001, 0.000, respectively). Conclusion:Carotid ΔVTI and ΔFTc monitored by bedside ultrasound before and after PLR could be as effective as conventional indicators in predicting fluid responsiveness in critically ill patients, and the predictive value of ΔVTI was better than others.

O comportamento da pressão arterial após elevação da pressão parcial positiva final pode auxiliar na determinação do status de fluido-responsividade em pacientes com choque séptico? / Can the behavior of blood pressure after elevation of the positive end-expiratory pressure help to determine the fluid responsiveness status in patients with septic shock?

RESUMO Objetivo: Avaliar se a diminuição da pressão arterial provocada pela elevação da pressão parcial positiva final corresponde à variação da pressão de pulso como indicador de fluido-responsividade. Métodos: Estudo de caráter exploratório que incluiu prospectivamente 24 pacientes com choque séptico ventilados mecanicamente e submetidos a três etapas de elevação da pressão parcial positiva final: de 5 para 10cmH2O (nível da pressão parcial positiva final 1), de 10 para 15cmH2O (nível da pressão parcial positiva final 2) e de 15 para 20cmH2O (nível da pressão parcial positiva final 3). Alterações da pressão arterial sistólica, da pressão arterial média e da variação da pressão de pulso foram avaliadas durante as três manobras. Os pacientes foram classificados como responsivos (variação da pressão de pulso ≥ 12%) e não responsivos a volume (variação da pressão de pulso < 12%). Resultados: O melhor desempenho para identificar pacientes com variação da pressão de pulso ≥ 12% foi observado no nível da pressão parcial positiva final 2: variação de pressão arterial sistólica de -9% (área sob a curva de 0,73; IC95%: 0,49 - 0,79; p = 0,04), com sensibilidade de 63% e especificidade de 80%. A concordância foi baixa entre a variável de melhor desempenho (variação de pressão arterial sistólica) e a variação da pressão de pulso ≥ 12% (kappa = 0,42; IC95%: 0,19 - 0,56). A pressão arterial sistólica foi < 90mmHg no nível da pressão parcial positiva final 2 em 29,2% dos casos e em 41,6,3% no nível da pressão parcial positiva final 3. Conclusão: Variações da pressão arterial em resposta à elevação da pressão parcial positiva final não refletem de modo confiável o comportamento da variação da pressão de pulso para identificar o status da fluido-responsividade.

Abstract Objective: To evaluate whether the decrease in blood pressure caused by the increase in the positive end-expiratory pressure corresponds to the pulse pressure variation as an indicator of fluid responsiveness. Methods: This exploratory study prospectively included 24 patients with septic shock who were mechanically ventilated and subjected to three stages of elevation of the positive end-expiratory pressure: from 5 to 10cmH2O (positive end-expiratory pressure level 1), from 10 to 15cmH2O (positive end-expiratory pressure level 2), and from 15 to 20cmH2O (positive end-expiratory pressure level 3). Changes in systolic blood pressure, mean arterial pressure, and pulse pressure variation were evaluated during the three maneuvers. The patients were classified as responsive (pulse pressure variation ≥ 12%) or unresponsive to volume replacement (pulse pressure variation < 12%). Results: The best performance at identifying patients with pulse pressure variation ≥ 12% was observed at the positive end-expiratory pressure level 2: -9% systolic blood pressure variation (area under the curve 0.73; 95%CI: 0.49 - 0.79; p = 0.04), with a sensitivity of 63% and specificity of 80%. Concordance was low between the variable with the best performance (variation in systolic blood pressure) and pulse pressure variation ≥ 12% (kappa = 0.42; 95%CI: 0.19 - 0.56). The systolic blood pressure was < 90mmHg at positive end-expiratory pressure level 2 in 29.2% of cases and at positive end-expiratory pressure level 3 in 41.63% of cases. Conclusion: Variations in blood pressure in response to the increase in positive end-expiratory pressure do not reliably reflect the behavior of the pulse pressure as a measure to identify the fluid responsiveness status.

Plethysmographic variability index as a tool to assess fluid responsiveness in critically ill patients: a correlation study with inferior vena cava distensibility index

Background: In critically ill patients in the intensive care unit (ICU), early aggressive fluid replacement is the cornerstone of resuscitation. Traditionally employed static measures of fluid responsiveness have a poor predictive value. It is therefore imperative to employ dynamic measures of fluid responsiveness that take into account the heart lung interactions in the mechanically ventilated patients. The main objective of this study was to evaluate the reliability of one such non-invasive dynamic index: Plethysmographic variability index (PVI) compared to the widely employed Inferior vena cava distensibility index (dIVC).Methods: Seventy-six adult patients admitted at a tertiary care mixed ICU, who developed hypotension (MAP<65mmHg), were included in the study. PVI was recorded using the MASIMO-7 monitor and dIVC measurements done using Terason ultrasound. Based on the dIVC measurement threshold of 18%, the patients were classified into volume responders and non-responders. The hemodynamic, PVI and dIVC measurements were recorded at pre specified time points following a fluid challenge of 20 ml/kg crystalloid infusion.Results: Baseline PVI values were significantly higher in the responders (22.3±8.2) compared to non-responders (10.1±2.9) (p<0.001) and showed a declining trend at all time points in the responders. Similar declining trend was observed in the dIVC measurements. Overall, the Pearson correlation graph showed strong correlation between dIVC and PVI values at all time points (r=0.678, p=0.001). The ROC curve between the dIVC and PVI values revealed that Baseline PVI (Pre PVI) >15.5% discriminated between responders and non-responders with a 90.2% sensitivity and 75% specificity with an AUC of 0.84 (0.72-0.96) (p<0.001).Conclusions: There is good correlation between PVI values and measured dIVC values at baseline and following a fluid challenge. Thus, PVI may be an acceptable, real time, continuous, surrogate measure of fluid responsiveness in critically ill patients.

Progress in noninvasive assessment of fluid responsiveness / 中华全科医师杂志

Fluid infusion is one of the most common therapeutic measures in clinical practice.With the development of medical technology,the assessment of fluid responsiveness before fluid infusion has become simpler and less invasive.The assessment of fluid responsiveness is based on three aspects:cardiopulmonary interaction,volume-loading test and endogenous volume-loading test.This article reviews the progress in the assessment of fluid responsiveness with the application of ultrasound and noninvasive continuous cardiac output monitoring,and the prospect of future improvement.

Monitoring center venous pressure to guide the treatment of acute circulatory failure: give up or persist / 中国小儿急救医学

Central venous pressure (CVP) is one of the most commonly used parameters in hemodynamic monitoring, and monitoring CVP to guide the treatment of acute circulatory failure is a relatively common clinical method.However, many studies have pointed out that CVP is affected by many factors and has great limitations, which cannot provide help for the treatment of acute circulatory failure.This review summarized the analysis of the working principle of CVP, its value in treatment and influencing factors.The main purpose is to get a better understanding of CVP.

The role of noninvasive ultrasound blood flow velocity time integral in the evaluation of fluid responsiveness during passive leg raising test / 中华急诊医学杂志

Objective To evaluate the feasibility of using noninvasive ultrasonic cardiac output monitor USCOM velocity time integral (VTI) as the observation index of PLR.Methods This prospective study recruited 36 septic shock or acute pancreatitis patients from October 2014 to October 2016 in the resuscitation room and EICU of Peking Union Medical College Hospital.The change of VTI and plus pressure before and after PLR (⊿VTIplr and ⊿pp),and the change of VTI and stroke volume before and after 500 mL of volume expansion (⊿VTIve and ⊿SV) were recorded.Fluid response positive was defined as stroke volume increase more than 15％ after volume expansion.Results ⊿VTIplr was positively correlated with ⊿SV (Spearman correlation coefficient r=0.888,P＜0.01).The predicting value of⊿VTIve,⊿VTIplr and ⊿PP in fluid response were as follows:the sensitivity of ⊿VTIve in ＞15％ was 94.7％,the specificity was 94.1％,area under the ROC curve was 0.989;the sensitivity of⊿ VTIplr in ＞12％ was 84.2％,the specificity was 88.2％,area under the ROC curve was 0.916;and the sensitivity of⊿ PP in ＞10.5％ was 78.9％,the specificity was 88.2％,the area under the ROC curve was 0.870.Conclusions ⊿ VTIplr measured by USCOM before and after the PLR is a sensitive and specific index.It is better than the classic index ⊿ PP.⊿ VTIplr measured by USCOM is completely noninvasive,which has very good application prospect in the emergency department.

Monitoring center venous pressure to guide the treatment of acute circulatory failure:give up or persist / 中国小儿急救医学

Central venous pressure (CVP) is one of the most commonly used parameters in hemody-namic monitoring,and monitoring CVP to guide the treatment of acute circulatory failure is a relatively com-mon clinical method. However,many studies have pointed out that CVP is affected by many factors and has great limitations,which cannot provide help for the treatment of acute circulatory failure. This review summa-rized the analysis of the working principle of CVP,its value in treatment and influencing factors. The main purpose is to get a better understanding of CVP.

Determining the Merit of Inferior Vena Cava Distensibility Index in The Estimation of Fluid Responsiveness in Ventilated Septic Patient in Intensive Care Unit

@#Introduction: There is no single haemodynamic parameters either static central venous pressure (CVP) or dynamic stroke volume variation, inferior vena cava distensibility index (SVV,IVCd) that can be used precisely to assess fluid responsiveness. It must be performed concurrently with clinical assessment. Therefore, this study was conducted to determine the correlation between these 3 parameters. Methods: This was a cross sectional non-interventional study conducted in intensive care unit. Each patient who fulfilled the criteria will have their CVP, SVV and IVCd measured instantaneously. Analysis of correlation was done using bivariate (Pearson) correlation, while agreement between SVV and IVCd was assessed using Cohen’s Kappa analysis. Results: A total of 37 patients were enrolled in this study. 70.3% were males and 29.7% were females. Mean age was 59.7 ± 13.3. Mean APACHE score was 24.1 ± 6.1. IVCd had significant positive correlation with SVV (r = 0.391, p = 0.017). Agreement between IVCd and SVV was 0.329 (0.95 CI = 0.0174 – 0.6412; p = 0.033). There was non-significant negative correlation between IVCd with CVP and SVV with CVP with r = -0.155 (p=0.359) and r = -0.068 (p= 0.691) respectively. Conclusion: There is only fair correlation between IVCd and SVV in determining fluid responsiveness. However, CVP does not correlate to both SVV and IVCd. Neither one of them is a good method in assessing fluid responsiveness during standard care in our centre. Therefore, the usage of above methods needs to combine with clinical parameters to yield better result.

The utility of point-of-care ultrasound in the assessment of volume status in acute and critically ill patients / 世界急诊医学杂志（英文）

BACKGROUND@# Volume resuscitation has only been demonstrated to be effective in approximately fifty percent of patients. The remaining patients do not respond to volume resuscitation and may even develop adverse outcomes (such as acute pulmonary edema necessitating endotracheal intubation). We believe that point-of-care ultrasound is an excellent modality by which to adequately predict which patients may benefit from volume resuscitation.@*DATA RESOURCES@#We performed a search using PubMed, Scopus, and MEDLINE. The following search terms were used: fluid responsiveness, ultrasound, non-invasive, hemodynamic, fluid challenge, and passive leg raise. Preference was given to clinical trials and review articles that were most relevant to the topic of assessing a patient’s cardiovascular ability to respond to intravenous fluid administration using ultrasound.@*RESULTS@#Point-of-care ultrasound can be easily employed to measure the diameter and collapsibility of various large vessels including the inferior vena cava, common carotid artery, subclavian vein, internal jugular vein, and femoral vein. Such parameters are closely related to dynamic measures of fluid responsiveness and can be used by providers to help guide fluid resuscitation in critically ill patients.@*CONCLUSION@# Ultrasound in combination with passive leg raise is a non-invasive, cost- and time-effective modality that can be employed to assess volume status and response to fluid resuscitation. Traditionally sonographic studies have focused on the evaluation of large veins such as the inferior vena cava, and internal jugular vein. A number of recently published studies also demonstrate the usefulness of evaluating large arteries to predict volume status.

Quest for the holy grail: Assessment of echo-derived dynamic parameters as predictors of fluid responsiveness in patients with acute aneurysmal subarachnoid hemorrhage

Background: Acute aneurysmal subarachnoid hemorrhage (aSAH) is a potentially devastating event often presenting with a plethora of hemodynamic fluctuations requiring meticulous fluid management. The aim of this study was to assess the utility of newer dynamic predictors of fluid responsiveness such as Delta down (DD), superior vena cava collapsibility index (SVCCI), and aortic velocity time integral variability (VTIAoV) in patients with SAH undergoing neurosurgery. Materials and Methods: Fifteen individuals with SAH undergoing surgery for intracranial aneurysmal clipping were enrolled in this prospective study. Postinduction, vitals, anesthetic parameters, and the study variables were recorded as the baseline. Following this, patients received a fluid bolus of 10 ml/kg of colloid over 20 min, and measurements were repeated postfluid loading. Continuous variables were expressed as mean ± standard deviation and compared using Student's t-test, with a P < 0.05 considered statistically significant. The predictive ability of variables for fluid responsiveness was determined using Pearson's coefficient analysis (r). Results: There were 12 volume responders and 3 nonresponders (NR). DD >5 mm Hg was efficient in differentiating the responders from NR (P < 0.05) with a sensitivity and specificity of 90% and 85%, respectively, with a good predictive ability to identify fluid responders and NR; r = 0.716. SVCCI of >38% was 100% sensitive and 95% specific in detecting the volume status and in differentiating the responders from NR (P < 0.05) and is an excellent predictor of fluid responsive status; r = 0.906. VTIAoV >20% too proved to be a good predictor of fluid responsiveness, with a sensitivity and specificity of 100% and 90%, respectively, with a predictive power; r = 0.732. Conclusion: Our study showed that 80% of patients presenting with aSAH for intracranial aneurysm clipping were fluid responders with normal hemodynamic parameters such as heart rate and blood pressure. Among the variables, SVCCI >38% appears to be an excellent predictor followed by VTIAoV >20% and DD >5 mmHg in assessing the fluid status in this population.

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.

Mandatory criteria for the application of variability-based parameters of fluid responsiveness: a prospective study in different groups of ICU patients / 浙江大学学报（英文版）（B辑：生物医学和生物技术）

BACKGROUND AND OBJECTIVE@#Stroke volume variation (SVV) has high sensitivity and specificity in predicting fluid responsiveness. However, sinus rhythm (SR) and controlled mechanical ventilation (CV) are mandatory for their application. Several studies suggest a limited applicability of SVV in intensive care unit (ICU) patients. We hypothesized that the applicability of SVV might be different over time and within certain subgroups of ICU patients. Therefore, we analysed the prevalence of SR and CV in ICU patients during the first 24 h of PiCCO-monitoring (primary endpoint) and during the total ICU stay. We also investigated the applicability of SVV in the subgroups of patients with sepsis, cirrhosis, and acute pancreatitis.@*METHODS@#The prevalence of SR and CV was documented immediately before 1241 thermodilution measurements in 88 patients.@*RESULTS@#In all measurements, SVV was applicable in about 24%. However, the applicability of SVV was time-dependent: the prevalence of both SR and CV was higher during the first 24 h compared to measurements thereafter (36.1% vs. 21.9%; P<0.001). Within different subgroups, the applicability during the first 24 h of monitoring ranged between 0% in acute pancreatitis, 25.5% in liver failure, and 48.9% in patients without pancreatitis, liver failure, pneumonia or sepsis.@*CONCLUSIONS@#The applicability of SVV in a predominantly medical ICU is only about 25%-35%. The prevalence of both mandatory criteria decreases over time during the ICU stay. Furthermore, the applicability is particularly low in patients with acute pancreatitis and liver failure.

Study of blood flow velocity and respiratory variability in different parts of left heart by ultrasonography / 中华急诊医学杂志

Objective To investigate the correlation between blood flow velocity and respiratory variability in different parts of left heart of patients with sepsis via measuring the flow velocity of the E-wave of mitral valve (MV), peak flow velocity of left ventricular outflow tract (LVOT), and respiratory variability (ΔVpeak) by ultrasonography. Methods Totally 81 patients with sepsis hospitalized in ICU were chosen consecutively from March 2017 to October 2017. Each patient's flow velocity of the E-wave of mitral valve and peak flow velocity of LVOT was inspected, by apical four-chamber view and apical five-chamber view respectively, to calculate the respiratory variability. Results (1) Of the 81 patients with sepsis, 33 patients (40.7％) had complete control of mechanical ventilation (no spontaneous breathing trigger), and 48 patients (59.3％) had spontaneous breathing and incomplete control of mechanical ventilation (partial spontaneous breathing trigger). (2) There was no significant difference in the mean values of flow velocity of the E-wave of mitral valve and peak flow velocity of LVOT in patients with sepsis. Whereas the flow velocity of the E-wave of mitral valve (0.15±0.05) was greater than the peak flow velocity of LVOT (0.12±0.04) with statistical significance (P<0.01). In sepsis patients with complete control of mechanical ventilation (no spontaneous breathing trigger), respiratory variability in the flow velocity of the E-wave of mitral valve (0.17±0.06) was significantly greater than the peak flow velocity of LVOT (0.11±0.03), P<0.01, whereas in sepsis patients with incomplete control of mechanical ventila tion (partial spontaneous breathing trigger), there was no statistically significant difference between the respiratory variability in flow velocity of the E-wave of mitral valve (0.14±0.04) and in the peak flow velocity of LVOT (0.13±0.03), P=0.102. (3) The respiratory variability in flow velocity of the E-wave of mitral valve was correlated with the peak flow velocity of LVOT (r=0.670, P<0.01). The flow velocity of the E-wave of mitral valve was all correlated with the peak flow velocity of LVOT in both sepsis patients with complete control of mechanical ventilation (no spontaneous breathing trigger) (r=0.894, P<0.01), and sepsis patients with incomplete control of mechanical ventilation (partial spontaneous breathing trigger) (r=0.774, P<0.01), respectively. Conclusions The respiratory variability in flow velocity of the E-wave of mitral valve was correlated with that in the peak flow velocity of LVOT, which may provide a new indicator in evaluating the fluid responsiveness of patients with sepsis.

Accuracy of respiratory variations of internal jugular vein in monitoring fluid responsiveness in patients undergoing radical gastrectomy for gastric cancer / 中华麻醉学杂志

Objective To evaluate the accuracy of respiratory variations of internal jugular vein (IJV) in monitoring fluid responsiveness in patients undergoing radical gastrectomy for gastric cancer.Methods Fifty American Society of Anesthesiologists physical status Ⅰ or Ⅱ patients of both sexes,aged 40-64 yr,scheduled for elective radical gastrectomy for gastric cancer,were enrolled in this study.Before induction of anesthesia,the hemodynamic parameters such as heart rate,central venous pressure,cardiac index,stroke volume index (SVI),stroke volume variation and respiratory variation of IJV were recorded after haemodynamics was stable and were recorded again at 10 min after endotracheal intubation,and a loading dose of 6％ 130/0.4 hydroxyethyl starch 7 ml/kg was infused over 15 min.The parameters mentioned above were recorded within 5 min after loading dose.Patients were divided into 2 groups according to the percentage of increase in SVI (△SVI) after volume expansion:△SVI≥ 15％ was considered to be a positive response (responder group) and △SVI＜15％ was considered to be a negative response after volume expansion (non-responder group).Results The area under the receiver operating characteristic curve of respiratory variations of IJV in monitoring fluid responsiveness and 95％ confidence interval were 0.852 (0.744-0.961).Respiratory variation of IJV 24.6％ was considered as the cut-off value and used to monitor fluid responsiveness,and the sensitivity and specificity were 67.6％ and 92.3％,respectively.Conclusion Respiratory variation of IJV can be considered as an effective index in monitoring fluid responsiveness in the patients undergoing radical gastrectomy for gastric cancer.

Predictive value of central venous-to-arterial carbon dioxide partial pressure difference for fluid responsiveness in septic shock patients: a prospective clinical study / 中华危重病急救医学

Objective To evaluate the accuracy of central venous-to-arterial carbon dioxide partial pressure difference (Pcv-aCO2) before and after rapid rehydration test (fluid challenge) in predicting the fluid responsiveness in patients with septic shock. Methods A prospective observation was conducted. Forty septic shock patients admitted to medical intensive care unit (ICU) of Peking Union Medical College Hospital from October 2015 to June 2017 were enrolled. All of the patients received fluid challenge in the presence of invasive hemodynamic monitoring. Heart rate (HR), blood pressure, cardiac index (CI), Pcv-aCO2 and other physiological variables were recorded at 10 minutes before and immediately after fluid challenge. Fluid responsiveness was defined as an increase in CI greater than 10% after fluid challenge, whereas fluid non-responsiveness was defined as no increase or increase in CI less than 10%. The correlation between Pcv-aCO2 and CI was explored by Pearson correlation analysis. Receiver operating characteristic (ROC) curves were established to evaluate the discriminatory abilities of baseline and the changes after fluid challenge in Pcv-aCO2 and other physiological variables to define the fluid responsiveness. The patients were separated into two groups according to the initial value of Pcv-aCO2. The cut-off value of 6 mmHg (1 mmHg = 0.133 kPa) was chosen according to previous studies. The discriminatory abilities of baseline and the change in Pcv-aCO2(ΔPcv-aCO2) were assessed in each group. Results A total of 40 patients were finally included in this study. Twenty-two patients responded to the fluid challenge (responders). Eighteen patients were fluid non-responders. There was no significant difference in baseline physiological variable between the two groups. Fluid challenge could increase CI and blood pressure significantly, decrease HR notably and had no effect on Pcv-aCO2 in fluid responders. In non-responders, blood pressure was increased significantly and CI, HR, Pcv-aCO2 showed no change after fluid challenge. Pcv-aCO2 was comparable in responders and non-responders. In 40 patients, CI and Pcv-aCO2 was inversely correlated before fluid challenge (r = -0.391, P = 0.012) and the correlation between them weakened after fluid challenge (r = -0.301, P = 0.059). There was no significant correlation between the changes in CI and Pcv-aCO2 after fluid challenge (r = -0.164, P = 0.312). The baseline Pcv-aCO2 and ΔPcv-aCO2 could not discriminate between responders and non-responders, with the area under ROC curve (AUC) of 0.50 [95% confidence interval (95%CI) =0.32-0.69] and 0.51 (95%CI = 0.33-0.70), respectively. HR and blood pressure before fluid challenge and their changes after fluid challenge showed very poor discriminative performances. Before fluid challenge, 16 patients had a Pcv-aCO2 > 6 mmHg. Their mean CI was significantly lower and Pcv-aCO2 was significantly higher than that in 24 patients whose Pcv-aCO2 ≤6 mmHg [n = 24; CI (mL·s-1·m-2): 48.3±11.7 vs. 65.0±18.3, P < 0.01; Pcv-aCO2 (mmHg): 8.4±1.9 vs. 2.9±2.8, P < 0.01]. Pcv-aCO2was decreased significantly after fluid challenge in patients with an initial Pcv-aCO2 > 6 mmHg and their ΔPcv-aCO2 was notably different as compared with the patients whose baseline Pcv-aCO2≤6 mmHg (mmHg: -3.8±3.4 vs. 0.9±2.9, P < 0.01). 68.8% (11/16) patients responded to the fluid challenge in patients with an initial Pcv-aCO2 > 6 mmHg. The AUC of the baseline Pcv-aCO2 and ΔPcv-aCO2 to define fluid responsiveness was 0.85 (95%CI = 0.66-1.00) and 0.84 (95%CI = 0.63-1.00), respectively, and the positive predictive value was 1 when the cut-off value was 8.0 mmHg and -4.2 mmHg, respectively. 45.8% (11/24) patients responded to the fluid challenge in patients whose baseline Pcv-aCO2≤6 mmHg. There was no predictive value of baseline Pcv-aCO2 and ΔPcv-aCO2 on fluid responsiveness. Conclusion Pcv-aCO2 and its change cannot serve as a surrogate of the change in cardiac output to define the response to fluid challenge in septic shock patients whose baseline Pcv-aCO2≤6 mmHg, while the predictive values of baseline Pcv-aCO2and the change in Pcv-aCO2 are presented in patients with the initial value of Pcv-aCO2 > 6 mmHg. Clinical Trial Registration Clinical Trials, NCT01941472.

Variability of peripheral arterial peak velocity predicts fluid responsiveness in patients with septic shock / 中华危重病急救医学

Objective To explore the accuracy of fluid responsiveness assessment by variability of peripheral arterial peak velocity and variability of inferior vena cava diameter (ΔIVC) in patients with septic shock. Methods A prospective study was conducted. The patients with septic shock undergoing mechanical ventilation (MV) admitted to intensive care unit (ICU) of Beijing Electric Power Hospital from January 2016 to December 2017 were enrolled. According to sepsis bundles of septic shock, volume expansion (VE) was conducted. The increase in cardiac index (ΔCI) after VE ≥ 10% was defined as liquid reaction positive (responsive group), ΔCI < 10% was defined as the liquid reaction negative (non-responsive group). The hemodynamic parameters [central venous pressure (CVP), intrathoracic blood volume index (ITBVI), stroke volume variation (SVV), ΔIVC, variability of carotid Doppler peak velocity (ΔCDPV), and variability of brachial artery peak velocity (ΔVpeak-BA)] before and after VE were monitored. The correlations between the hemodynamic parameters and ΔCI were explored by Pearson correlation analysis. Receiver operating characteristic (ROC) curve was plotted to analyze the predictive value of all hemodynamic parameters on fluid responsiveness. Results During the study, 74 patients with septic shock were included, of whom 9 were excluded because of peripheral artery stenosis, recurrent arrhythmia or abdominal distension influencing the ultrasound examination, and 65 patients were finally enrolled in the analysis. There were 31 patients in the responsive group and 34 in the non-responsive group. SVV, ΔIVC, ΔCDPV and ΔVpeak-BA before VE in responsive group were significantly higher than those of the non-responsive group [SVV: (12.3±2.4)% vs. (9.2±2.1)%, ΔIVC: (22.3±5.3)% vs. (15.5±3.7)%, ΔCDPV: (15.3±3.3)% vs. (10.3±2.4)%, ΔVpeak-BA: (14.5±3.3)% vs. (9.6±2.3)%, all P < 0.05]. There was no significant difference in CVP [mmHg (1 mmHg = 0.133 kPa): 7.5±2.5 vs. 8.2±2.6] or ITBVI (mL/m2: 875.2±173.2 vs. 853.2±192.0) between the responsive group and non-responsive group (both P > 0.05). There was no significant difference in hemodynamic parameter after VE between the two groups. Correlation analysis showed that SVV, ΔIVC, ΔCDPV, and ΔVpeak-BA before VE showed significant linearity correlation with ΔCI (r value was 0.832, 0.813, 0.854, and 0.814, respectively, all P < 0.05), but no correlation was found between CVP and ΔCI (r = -0.342, P > 0.05) as well as ITBVI and ΔCI (r = -0.338, P > 0.05). ROC curve analysis showed that the area under ROC curve (AUC) of SVV, ΔIVC, ΔCDPV, and ΔVpeak-BA before VE for predicting fluid responsiveness was 0.857, 0.826, 0.906, and 0.866, respectively, which was significantly higher than that of CVP (AUC = 0.611) and ITBVI (AUC = 0.679). When the optimal cut-off value of SVV for predicting fluid responsiveness was 11.5%, the sensitivity was 70.4%, and the specificity was 94.7%. When the optimal cut-off value of ΔIVC was 20.5%, the sensitivity was 60.3%, and the specificity was 89.7%. When the optimal cut-off value of ΔCDPV was 13.0%, the sensitivity was 75.2%, and the specificity was 94.9%. When the optimal cut-off value of ΔVpeak-BA was 12.7%, the sensitivity was 64.8%, and the specificity was 89.7%. Conclusions Ultrasound assessment of ΔIVC, ΔCDPV, and ΔVpeak-BA could predict fluid responsiveness in patients with septic shock receiving mechanical ventilation. ΔCDPV had the highest predictive value among these parameters.

The ultrasonic monitoring coupled with passive leg raising test for evaluation of fluid responsiveness in critical patients / 中华急诊医学杂志

Objective To explore the value of predicting fluid responsiveness using velocity time index variation (△VTI) and stroke volume variation (△SV) before and after passive leg raising (PLR)monitored by bedside temporary test equipment (TTE).Methods A cohort of 42 patients supported with mechanical ventilation in our hospital admitted from October 2014 to October 2015 were prospectively selected.The hemodynamic variables including heart rate (HR),mean arterial pressure (MAP),central venous pressure (CVP),VTI,SV and other parameters were monitored before and after after undergoing PLR.Fluid resuscitation volume expansion test was carried out after stroke volume index (SVI) monitored by pulse indicator continuous cardiac output monitoring (PICCO).Patients were divided into fluid responsiveness positive group and fluid responsiveness negative group according to presence or absence of SVI ≥ 15％ after fluid resuscitation volume expansion.Results Of 42 patients,22 belonged to fluid responsiveness positive group,20 got into fluid responsiveness negative group.There were no significant differences in basic clinical data between two groups.Before and after PLR,there were no distinct changes in HR and CVP (P ＞ 0.05),while MAP,VTI and SV increased significantly (P ＜ 0.05) after PLR in fluid responsiveness positive group.Contrarily,there were no noticeable changes in MAP and SV after PLR (P ＞ 0.05),but HR,CVP and VTI increased significantly (P ＜ 0.05) in fluid responsiveness negative group.The degrees of △VTI and △SV in fluid responsiveness positive group were much higher than those in fluid responsiveness negative group (P ＜0.05).According to SVI ≥ 15％ monitored by PICCO after fluid resuscitation volume expansion test as a standard,the area under the ROC (AUC) of △VTI between prePLR and post-PLR was 0.75 (95％ CI:O.593-0.907,P ＜ 0.01),the sensitivity and specificity were 63.6％ and 95％ respectively using △VTI 15.6％ as threshold value.The AUC of △SV was 0.844 (95％CI:O.716-0.972,P ＜0.01),the sensitivity and specificity were 81.8％ and 85.0％ respectively using △SV 10.5％ as threshold value.Conclusion △VTI and △SV monitored by TTE before and after PLR could be employed for predicting fluid responsiveness of critical patients under the status of spontaneous respiration.Their value for prediction of critical patients could be further improved by combined employment of these two indexes of variation.

Validity of stroke volume variation for predicting fluid responsiveness in different grades of intra-abdominal pressure / 临床麻醉学杂志

Objective To evaluate the validity of stroke volume variation (SVV) for predicting fluid responsiveness in different grades of intra-abdominal pressure (IAP).Methods Forty pigs were involved in the study.Hypovolemia was made by blood withdraw of 30% of estimated blood volume from each animal via carotid artery.All the pigs were randomized into four groups namly 0 mm Hg (L0), 15 mm Hg (L15), 25 mm Hg (L25) and 35 mm Hg (L35).Nitrogen was inflated slowly till IAP to 0, 15, 25 and 35 mm Hg.Fluid loading was performed with 500 ml hydroxyethyl starch within 30 minutes.Hemodynamic parameters were evaluated by the thermodilution technique of pulse induced continuous cardiac output (PiCCO).SVV and stroke volume (SV) were measured before and after fluid loading.Results In groups L0 and L15, SVV was positive correlated with changes in SV (r=0.888, 0.942, respectively, P<0.05).In groups L25 and L35, there were poor correlations between SVV and changes in SV(r=0.068,-0.114, respectively).Conclusion When IAP was slightly increased up to 15 mm Hg, SVV remains an effectiveness index to predict fluid responsiveness index, however it failed to assess fluid responsiveness effectively when IAP is further raised up to 25 mm Hg or more.