Respiratory changes in inferior vena cava diameter are helpful in predicting fluid responsiveness in ventilated septic patients

Resuscitative Ultrasound and Protocols

The management of patients in shock or arrest is a critical aspect of emergency medicine and critical care. Rapid and accurate assessment is paramount in determining the underlying causes and initiating timely interventions. This article provides a summary of essential ultrasound protocols for the critically ill patient including the extended focused assessment with sonography for trauma (EFAST), rapid ultrasound for shock and hypotension (RUSH), and sonography in hypotension and cardiac arrest in the emergency department (SHoC-ED).

[Bedside imaging]

Sonography, in particular echocardiography, is essential in the assessment of volume status and hemodynamics in critically ill patients. Examination of the left ventricle, in addition to assessing ventricular function, provides valuable information, including the "kissing papillary muscle sign," which may indicate fluid responsiveness. Examination of the right ventricle is also important because it is sensitive to both volume and pressure overload. Assessment of diastolic function and measurement of inferior vena cava width and variability provide clues to left and right ventricular preload, respectively. Measurement of stroke volume and cardiac output allows further assessment of hemodynamics and also permits determination of stroke volume variability.

[Functional hemodynamic monitoring]

BACKGROUND

Critically ill patients in the intensive care unit require intensified monitoring to control the treatment with volume and/or vasoactive substances.

RESEARCH QUESTION

What role does functional hemodynamic monitoring play in controlling treatment and what techniques are used to manage this?

MATERIAL AND METHODS

Review of the current literature.

RESULTS AND DISCUSSION

Precise knowledge of the physiology of the cardiovascular system as well as the pathophysiology of individual clinical pictures and the possibilities of invasive and noninvasive monitoring are the prerequisites for the indications, implementation and interpretation of functional hemodynamic monitoring. An understanding of the heart-lung interaction and the influence of invasive ventilation on the volumetric target parameters, such as stroke volume variation, systolic pressure variation and pulse pressure variation as well as sonography of the inferior vena cava are indispensable prerequisites for the question of volume responsiveness. Other maneuvers, such as the passive leg raising test, can be very helpful when deciding on volume administration in everyday clinical practice. Static parameters such as central venous pressure generally play no role and if any only a subordinate one.

Critical Care Ultrasound in Shock: A Comprehensive Review of Ultrasound Protocol for Hemodynamic Assessment in the Intensive Care Unit

Shock is a life-threatening condition that requires prompt recognition and treatment to prevent organ failure. In the intensive care unit, shock is a common presentation, and its management is challenging. Critical care ultrasound has emerged as a reliable and reproducible tool in diagnosing and classifying shock. This comprehensive review proposes an ultrasound-based protocol for the hemodynamic assessment of shock to guide its management in the ICU. The protocol classifies shock as either low or high cardiac index and differentiates obstructive, hypovolemic, cardiogenic, and distributive etiologies. In distributive shock, the protocol proposes a hemodynamic-based approach that considers the presence of dynamic obstruction, fluid responsiveness, fluid tolerance, and ventriculo-arterial coupling. The protocol gives value to quantitative measures based on critical care ultrasound to guide hemodynamic management. Using critical care ultrasound for a comprehensive hemodynamic assessment can help clinicians diagnose the etiology of shock and define the appropriate treatment while monitoring the response. The protocol's use in the ICU can facilitate prompt recognition, diagnosis, and management of shock, ultimately improving patient outcomes.

Assessment of fluid responsiveness using pulse pressure variation, stroke volume variation, plethysmographic variability index, central venous pressure, and inferior vena cava variation in patients undergoing mechanical ventilation: a systematic review and meta-analysis

IMPORTANCE

Maneuvers assessing fluid responsiveness before an intravascular volume expansion may limit useless fluid administration, which in turn may improve outcomes.

OBJECTIVE

To describe maneuvers for assessing fluid responsiveness in mechanically ventilated patients.

REGISTRATION

The protocol was registered at PROSPERO: CRD42019146781.

INFORMATION SOURCES AND SEARCH

PubMed, EMBASE, CINAHL, SCOPUS, and Web of Science were search from inception to 08/08/2023.

STUDY SELECTION AND DATA COLLECTION

Prospective and intervention studies were selected.

STATISTICAL ANALYSIS

Data for each maneuver were reported individually and data from the five most employed maneuvers were aggregated. A traditional and a Bayesian meta-analysis approach were performed.

RESULTS

A total of 69 studies, encompassing 3185 fluid challenges and 2711 patients were analyzed. The prevalence of fluid responsiveness was 49.9%. Pulse pressure variation (PPV) was studied in 40 studies, mean threshold with 95% confidence intervals (95% CI) = 11.5 (10.5-12.4)%, and area under the receiver operating characteristics curve (AUC) with 95% CI was 0.87 (0.84-0.90). Stroke volume variation (SVV) was studied in 24 studies, mean threshold with 95% CI = 12.1 (10.9-13.3)%, and AUC with 95% CI was 0.87 (0.84-0.91). The plethysmographic variability index (PVI) was studied in 17 studies, mean threshold = 13.8 (12.3-15.3)%, and AUC was 0.88 (0.82-0.94). Central venous pressure (CVP) was studied in 12 studies, mean threshold with 95% CI = 9.0 (7.7-10.1) mmHg, and AUC with 95% CI was 0.77 (0.69-0.87). Inferior vena cava variation (∆IVC) was studied in 8 studies, mean threshold = 15.4 (13.3-17.6)%, and AUC with 95% CI was 0.83 (0.78-0.89).

CONCLUSIONS

Fluid responsiveness can be reliably assessed in adult patients under mechanical ventilation. Among the five maneuvers compared in predicting fluid responsiveness, PPV, SVV, and PVI were superior to CVP and ∆IVC. However, there is no data supporting any of the above mentioned as being the best maneuver. Additionally, other well-established tests, such as the passive leg raising test, end-expiratory occlusion test, and tidal volume challenge, are also reliable.

Accuracy of Respiratory Variation in Inferior Vena Cava Diameter to Predict Fluid Responsiveness in Children Under Mechanical Ventilation

Proper assessment of fluid responsiveness using accurate predictors is crucial to guide fluid therapy and avoid the serious adverse effects of fluid overload. The main objective of this study was to investigate the accuracy of respiratory variations in inferior vena cava diameter (∆IVC) to predict fluid responsiveness in mechanically ventilated children. This prospective single-center study included 32 children (median age and weight of 17 months and 10 kg, respectively) who received a fluid infusion of 10 ml kg-1 of crystalloid solutions over 10 min. ∆IVC and respiratory variation in aortic blood flow peak velocity (∆Vpeak) were determined over one controlled respiratory cycle before and after fluid loading. Thirteen (41%) participants were fluid-responders. ∆IVC, ∆Vpeak, stroke volume index, and cardiac index were found to be predictors of fluid responsiveness. However, the area under the ROC curve of ∆IVC was smaller when compared to ∆Vpeak (0.709 vs. 0.935, p < 0.012). The best cut-off values were 7.7% for ∆IVC (sensitivity, 69.2%; specificity 78.9%, positive predictive value, 69.2%; and negative predictive value, 78.9%) and 18.2% for ∆Vpeak (sensitivity, 84.6%; specificity, 89.5%; positive predictive value, 84.6%; negative predictive value, 89.5%). Changes in stroke volume were positively correlated with ∆IVC (ρ = 0.566, p < 0.001) and ∆Vpeak (ρ = 0.603, p < 0.001). A significant correlation was also found between changes in MAP and ∆Vpeak (ρ = 0.382; p = 0.031), but the same was not observed with ∆IVC (ρ = 0.011; p = 0.951). In conclusion, ∆IVC was found to have a moderate accuracy in predicting fluid responsiveness in mechanically ventilated children and is an inferior predictor when compared to ∆Vpeak.

Effects of dynamic versus static parameter-guided fluid resuscitation in patients with sepsis: A randomized controlled trial

Background

Fluid resuscitation is an essential component for sepsis treatment. Although several studies demonstrated that dynamic variables were more accurate than static variables for prediction of fluid responsiveness, fluid resuscitation guidance by dynamic variables is not standard for treatment. The objectives were to determine the effects of dynamic inferior vena cava (IVC)-guided versus (vs.) static central venous pressure (CVP)-guided fluid resuscitation in septic patients on mortality; and others, i.e., resuscitation targets, shock duration, fluid and vasopressor amount, invasive respiratory support, length of stay and adverse events.

Methods

A single-blind randomized controlled trial was conducted at Thammasat University Hospital between August 2016 and April 2020. Septic patients were stratified by acute physiologic and chronic health evaluation II (APACHE II) <25 or ≥25 and randomized by blocks of 2 and 4 to fluid resuscitation guidance by dynamic IVC or static CVP.

Results

Of 124 patients enrolled, 62 were randomized to each group, and one of each was excluded from mortality analysis. Baseline characteristics were comparable. The 30-day mortality rates between dynamic IVC vs. static CVP groups were not different (34.4% vs. 45.9%, p=0.196). Relative risk for 30-day mortality of dynamic IVC group was 0.8 (95%CI=0.5-1.2, p=0.201). Different outcomes were median (interquartile range) of shock duration (0.8 (0.4-1.6) vs. 1.5 (1.1-3.1) days, p=0.001) and norepinephrine (NE) dose (6.8 (3.9-17.8) vs. 16.1 (7.6-53.6) milligrams, p=0.008 and 0.1 (0.1-0.3) vs. 0.3 (0.1-0.8) milligram⋅kilogram -1, p=0.017). Others were not different.

Conclusions

Dynamic IVC-guided fluid resuscitation does not affect mortality of septic patients. However, this may reduce shock duration and NE dose, compared with static CVP guidance.

Evaluation of Electrical Cardiometry to Assess Fluid Responsiveness in Patients with Acute Circulatory Failure: A Comparative Study with Transthoracic Echocardiography

Aim

Acute circulatory failure is commonly encountered in critically ill patients, that requires fluid administration as the first line of treatment. However, only 50% of patients are fluid-responsive. Identification of fluid responders is essential to avoid the harmful effects of overzealous fluid therapy. Electrical cardiometry (EC) is a non-invasive bedside tool and has proven to be as good as transthoracic echocardiography (TTE) to track changes in cardiac output. We aimed to look for an agreement between EC and TTE for tracking changes in cardiac output in adult patients with acute circulatory failure before and after the passive leg-raising maneuver.

Materials and methods

Prospective comparative study, conducted at a Tertiary Care Teaching Hospital.

Results

We recruited 125 patients with acute circulatory failure and found 42.4% (53 out of 125) to be fluid-responsive. The Bland-Altman plot analysis showed a mean difference of 2.08 L/min between EC and TTE, with a precision of 3.8 L/min. The limits of agreement (defined as bias ± 1.96SD), were -1.7 L/min and 5.8 L/min, respectively. The percentage of error between EC and TTE was 56% with acceptable limits of 30%.

Conclusion

The percentage error beyond the acceptable limit suggests the non-interchangeability of the two techniques. More studies with larger sample sizes are required to establish the interchangeability of EC with TTE for tracking changes in cardiac output in critically ill patients with acute circulatory failure.

How to cite this article

Sharma S, Ramachandran R, Rewari V, Trikha A. Evaluation of Electrical Cardiometry to Assess Fluid Responsiveness in Patients with Acute Circulatory Failure: A Comparative Study with Transthoracic Echocardiography. Indian J Crit Care Med 2024;28(7):650-656.

Septic cardiomyopathy phenotype in the critically ill may depend on antimicrobial resistance

Background

Sepsis is a life-threatening organ dysfunction, and septic cardiomyopathy (SCM) may complicate the course of the disease. Infection with multidrug-resistant (MDR) pathogens has been linked with worse outcomes. This study aims to evaluate SCM in patients with infections caused by different antimicrobial-resistant phenotypes.

Method

This retrospective study included patients with sepsis/septic shock, hospitalized, and intubated in the intensive care unit of the University Hospital of Larissa between January 2022 and September 2023 with echocardiographic data during the first two days after infection onset. The patients were divided into two groups: non-MDR-SCM group and MDR-SCM group. The cardiac function was compared between the two groups.

Result

A total of 62 patients were included in the study. Forty-four patients comprised the MDR-SCM and 18 the non-MDR-SCM group. Twenty-six patients (41.9%) presented with left ventricular (LV) systolic dysfunction, and ≤35% right ventricular fractional area change (RVFAC) was present in 56.4%. LV systolic function was more severely impaired in the non-MDR-SCM group (left ventricular ejection fraction, 35.8% ±4.9% vs. 45.6%±2.4%, P=0.049; LV outflow tract velocity time integral, [10.1±1.4] cm vs. [15.3±0.74] cm, P=0.001; LV-Strain, -9.02%±0.9% vs. -14.02%±0.7%, P=0.001). The MDR-SCM group presented with more severe right ventricular (RV) dilatation (right ventricular end-diastolic area/left ventricular end-diastolic area, 0.81±0.03 vs. 0.7±0.05, P=0.042) and worse RV systolic function (RVFAC, 32.3%±1.9% vs. 39.6%±2.7%, P=0.035; tricuspid annular plane systolic excursion, [15.9±0.9] mm vs. [18.1±0.9] mm, P=0.165; systolic tissue Doppler velocity measured at the lateral tricuspid annulus, [9.9±0.5] cm/s vs. [13.1±0.8] cm/s, P=0.002; RV-strain, -11.1%±0.7% vs. -15.1%±0.9%, P=0.002).

Conclusion

SCM related to MDR infection presents with RV systolic dysfunction predominance, while non-MDR-SCM is mainly depicted with LV systolic dysfunction impairment.

Dynamic changes of hepatic vein Doppler velocities predict preload responsiveness in mechanically ventilated critically ill patients

BACKGROUND

Assessment of dynamic parameters to guide fluid administration is one of the mainstays of current resuscitation strategies. Each test has its own limitations, but passive leg raising (PLR) has emerged as one of the most versatile preload responsiveness tests. However, it requires real-time cardiac output (CO) measurement either through advanced monitoring devices, which are not routinely available, or echocardiography, which is not always feasible. Analysis of the hepatic vein Doppler waveform change, a simpler ultrasound-based assessment, during a dynamic test such as PLR could be useful in predicting preload responsiveness. The objective of this study was to assess the diagnostic accuracy of hepatic vein Doppler S and D-wave velocities during PLR as a predictor of preload responsiveness.

METHODS

Prospective observational study conducted in two medical-surgical ICUs in Chile. Patients in circulatory failure and connected to controlled mechanical ventilation were included from August to December 2023. A baseline ultrasound assessment of cardiac function was performed. Then, simultaneously, ultrasound measurements of hepatic vein Doppler S and D waves and cardiac output by continuous pulse contour analysis device were performed during a PLR maneuver.

RESULTS

Thirty-seven patients were analyzed. 63% of the patients were preload responsive defined by a 10% increase in CO after passive leg raising. A 20% increase in the maximum S wave velocity after PLR showed the best diagnostic accuracy with a sensitivity of 69.6% (49.1-84.4) and specificity of 92.8 (68.5-99.6) to detect preload responsiveness, with an area under curve of receiving operator characteristic (AUC-ROC) of 0.82 ± 0.07 (p = 0.001 vs. AUC-ROC of 0.5). D-wave velocities showed worse diagnostic accuracy.

CONCLUSIONS

Hepatic vein Doppler assessment emerges as a novel complementary technique with adequate predictive capacity to identify preload responsiveness in patients in mechanical ventilation and circulatory failure. This technique could become valuable in scenarios of basic hemodynamic monitoring and when echocardiography is not feasible. Future studies should confirm these results.

Echocardiographic characteristics in neonates with septic shock

Clinical parameters used for hemodynamic assessment and titration of vasopressor therapy in neonates with septic shock have several limitations. Functional echocardiography is an emerging tool for bedside assessment of cardiac function and may be useful for diagnosis of shock and assessing the response to therapy. Data regarding echocardiographic parameters in neonates with shock is lacking. This prospective observational study was conducted in a Level III NICU with the primary objective of comparing echocardiographic characteristics of neonates with septic shock at diagnosis, following fluid boluses, and after maximum inotropic support [A1]. Additionally, we compared these characteristics with those of healthy stable neonates who were gestation and postnatal age-matched. A total of 36 neonates with septic shock and 30 gestation and postnatal age-matched controls were enrolled. The mean (SD) gestation and birth weight of neonates with septic shock were 30.6 (4.0) weeks and 1538 (728) g, respectively. Gram-negative bacilli constituted 78.9% of all isolates. At presentation, there was no significant difference between neonates with shock and controls in terms of ventricular outputs, shortening fraction, ratio of early to late diastolic trans-mitral flow velocity, and myocardial performance indices. The distensibility index of inferior vena cava was higher in neonates with shock compared to controls, (17% vs 10%, (p < 0.01)). Left ventricular output was 209 (92) and 227 (102) ml/kg/min (p = 0.53) and right ventricular output was 427 (203) and 459 (227) ml/kg/min, (p = 0.03), respectively, before and after inotropic therapy.     Conclusion: Echocardiographic parameters may not differentiate neonates with septic shock from hemodynamically stable neonates. Neonates with shock associated with predominantly gram-negative sepsis are not able to augment cardiac functions, either at the onset or after administration of inotropes.      Trial registration: (CTRI/2017/12/010766). What is known: • For neonates with shock, echocardiography is becoming increasingly popular as an objective method of evaluating hemodynamics. • In healthy preterm neonate, cardiac output has been known to increase in response to altered hemodynamics during states of increased oxygen demand. What is new: •  In the setting of septic shock induced by gram-negative organisms, echocardiographic parameters are less likely to assist in the assessment of the response to vasoactive agents. Cytokines, induced by gram-negative organisms, may alter adrenoreceptors in myocardium and vasculature.

Accuracy of Pocket-sized Ultrasound Devices to Evaluate Inferior Vena Cava Diameter and Variability in Critically Ill Patients

Purpose

By using inferior vena cava (IVC) measurements, clinicians can detect fluid status and responsiveness and find out the etiology of hypotension, acute heart failure, and sepsis easier. Pocket-sized ultrasound devices (PSUD) may take this advantage a few steps further by their lower costs, user-friendly interface, and easily applicable structure.In this study, we aimed to determine the diagnostic value of a PSUD compared with a standard ultrasound device (SD) for the measurement of IVC diameter (IVCD) and its respiratory variability.

Materials and methods

We measured the inspiratory, expiratory diameters of IVC, and calculated the inferior vena cava collapsibility index (IVCCI). We investigated 42 intensive care unit (ICU) patients.

Results

There was no difference in inspiratory (PSUD: 1.34 ± 0.67 cm; SD: 1.35 ± 0.68 cm) and expiratory (PSUD: 1.98 ± 0.53 cm; SD: 2.01 ± 0.49 cm) IVCD among measurements with PSUD and SD (p > 0.05). There was also no difference between IVCCI's measured with PSUD (39 ± 20%) and SD (39 ± 20%) (p > 0.05). The Bland-Altman analysis revealed that the width of 95% limits of agreement were similar for both devices. There was a good inter-device agreement among PSUD and SD for measurements of IVCD, and there was no difference between IVCCI's measured using both ultrasound devices.

Conclusion

We support that the idea of a PSUD is as reliable as a SD for IVC measurements.

How to cite this article

Inci K, Gürsel G. Accuracy of Pocket-sized Ultrasound Devices to Evaluate Inferior Vena Cava Diameter and Variability in Critically Ill Patients. Indian J Crit Care Med 2024;28(4):369-374.

Comprehensive temporal analysis of right ventricular function and pulmonary haemodynamics in mechanically ventilated COVID-19 ARDS patients

BACKGROUND

Cardiac injury is frequently reported in COVID-19 patients, the right ventricle (RV) is mostly affected. We systematically evaluated the cardiac function and longitudinal changes in severe COVID-19 acute respiratory distress syndrome (ARDS) admitted to the intensive care unit (ICU) and assessed the impact on survival.

METHODS

We prospectively performed comprehensive echocardiographic analysis on mechanically ventilated COVID-19 ARDS patients, using 2D/3D echocardiography. We defined left ventricular (LV) systolic dysfunction as ejection fraction (EF) < 40%, or longitudinal strain (LS) > - 18% and right ventricular (RV) dysfunction if two indices among fractional area change (FAC) < 35%, tricuspid annulus systolic plane excursion (TAPSE) < 1.6 cm, RV EF < 44%, RV-LS > - 20% were present. RV afterload was assessed from pulmonary artery systolic pressure (PASP), PASP/Velocity Time Integral in the right ventricular outflow tract (VTIRVOT) and pulmonary acceleration time (PAcT). TAPSE/PASP assessed the right ventriculoarterial coupling (VACR).

RESULTS

Among 176 patients included, RV dysfunction was common (69%) (RV-EF 41.1 ± 1.3%; RV-FAC 36.6 ± 0.9%, TAPSE 20.4 ± 0.4mm, RV-LS:- 14.4 ± 0.4%), usually accompanied by RV dilatation (RVEDA/LVEDA 0.82 ± 0.02). RV afterload was increased in most of the patients (PASP 33 ± 1.1 mmHg, PAcT 65.3 ± 1.5 ms, PASP/VTIRVOT, 2.29 ± 0.1 mmHg/cm). VACR was 0.8 ± 0.06 mm/mmHg. LV-EF < 40% was present in 21/176 (11.9%); mean LV-EF 57.8 ± 1.1%. LV-LS (- 13.3 ± 0.3%) revealed a silent LV impairment in 87.5%. A mild pericardial effusion was present in 70(38%) patients, more frequently in non-survivors (p < 0.05). Survivors presented significant improvements in respiratory physiology during the 10th ICU-day (PaO2/FiO2, 231.2 ± 11.9 vs 120.2 ± 6.7 mmHg; PaCO2, 43.1 ± 1.2 vs 53.9 ± 1.5 mmHg; respiratory system compliance-CRS, 42.6 ± 2.2 vs 27.8 ± 0.9 ml/cmH2O, all p < 0.0001). Moreover, survivors presented significant decreases in RV afterload (PASP: 36.1 ± 2.4 to 20.1 ± 3 mmHg, p < 0.0001, PASP/VTIRVOT: 2.5 ± 1.4 to 1.1 ± 0.7, p < 0.0001 PAcT: 61 ± 2.5 to 84.7 ± 2.4 ms, p < 0.0001), associated with RV systolic function improvement (RVEF: 36.5 ± 2.9% to 46.6 ± 2.1%, p = 0.001 and RV-LS: - 13.6 ± 0.7% to - 16.7 ± 0.8%, p = 0.001). In addition, RV dilation subsided in survivors (RVEDA/LVEDA: 0.8 ± 0.05 to 0.6 ± 0.03, p = 0.001). Day-10 CRS correlated with RV afterload (PASP/VTIRVOT, r: 0.535, p < 0.0001) and systolic function (RV-LS, 0.345, p = 0.001). LV-LS during the 10th ICU-day, while ΔRV-LS and ΔPASP/RVOTVTI were associated with survival.

CONCLUSIONS

COVID-19 improvements in RV function, RV afterload and RV-PA coupling at day 10 were associated with respiratory function and survival.

An Echocardiographic Approach for the Management of Shock: The Subcostal to Apical, Respiratory to Parasternal-Cardiac to Respiratory, Aortic to Stomach Protocol

Point of care ultrasound has become an integral part of critical care medicine, particularly for recognizing shock etiologies and guiding management. Most of the current ultrasonography guided shock protocols have been tailored towards a qualitative assessment of patients on presentation with shock. Unfortunately, the evolving nature of shock, particularly in the face of resuscitation and physiologic changes, demands a more sophisticated approach. This manuscript serves to present a comprehensive algorithm called the transthoracic Subcostal To Apical, Respiratory to paraSternal and transesophageal Cardiac to Respiratory, Aortic to StomacH ultrasonographic evaluations for the assessment of shock. This protocol is better suited for the critically ill patient in its ability to move beyond pattern recognition and focus on monitoring shock states from their presentation through their evolution. Not only is importance placed on the sequence of the exam, but also the identification of signs of chronic disease, the early incorporation of pulmonary evaluation, and the role for transesophageal imaging in critically ill patients with difficult surface imaging. Given the broad capabilities of bedside ultrasound, the Subcostal To Apical, Respiratory to paraSternal-Cardiac to Respiratory, Aortic to StomacH protocol serves as a multifaceted algorithm allowing for a nuanced and dynamic approach for the resuscitation of critically ill patients in shock.

Is caval index a sufficient parameter for determining and monitoring dehydration in intoxication patients?

BACKGROUND

Cases of intoxication are increasing day by day and these patients are presenting to emergency departments. These patients are usually individuals with poor self-care, inadequate oral intake, and unable to meet their own needs, and may have significant dehydration due to the agents they have taken. The caval index (CI) is a recently used index to determine fluid requirement and response.

AIMS

We aimed to evaluate the success of CI in determining and monitoring dehydration in intoxication patients.

METHODS

Our study was conducted prospectively in the emergency department of a single tertiary care center. A total of ninety patients were included in the study. Caval index was calculated by measuring inspiratory and expiratory inferior vena cava diameters. Caval index measurements were repeated after 2 and 4 h.

RESULTS

Patients who were hospitalized, took multiple drugs, or needed inotropic agents had significantly higher caval index levels. A further increase in caval index levels was observed on second and third caval index evaluations in patients who received inotropic agents along with fluid resuscitation. Levels of systolic blood pressure recorded at admission (0. hour) showed a significant correlation with caval index and shock index. Caval index and the shock index were highly sensitive and specific at predicting mortality.

CONCLUSION

In our study, we found that CI can be used as an index to assist emergency clinicians in determining and monitoring fluid requirement in cases of intoxication presenting to the emergency department.

Alternative Cardiac Point-of-Care Ultrasound Views

Point of care ultrasound (POCUS) and critical care echocardiography (CCE) is increasingly being used in intensive care units (ICUs). POCUS and CCE may be limited in some ICU patients because of inadequate information from standard echocardiographic windows. At the same time, data from POCUS and CCE in ICU may be critical to managing patients with cardiorespiratory failure. Alternative echocardiographic views done at the bedside by ICU practitioners may yield additional information or replace the missing data from the standard views. Information obtained from multiple echocardiographic views should be integrated and interpreted within the patient's other clinical information.

Rethinking Fluid Responsiveness during Septic Shock: Ameliorate Accuracy of Noninvasive Cardiac Output Measurements through Evaluation of Arterial Biomechanical Properties

Beat-to-beat estimates of cardiac output from the direct measure of peripheral arterial blood pressure rely on the assumption that changes in the waveform morphology are related to changes in blood flow and vasomotor tone. However, in septic shock patients, profound changes in vascular tone occur that are not uniform across the entire arterial bed. In such cases, cardiac output estimates might be inaccurate, leading to unreliable evaluation of fluid responsiveness. Pulse wave velocity is the gold-standard method for assessing different arterial biomechanical properties. Such methods might be able to guide, personalize and optimize the management of septic patients.

Diagnostic Adjunct Techniques in the Assessment of Hypovolemia: A Prospective Pilot Project

INTRODUCTION

Measuring the hypovolemic resuscitation end point remains a critical care challenge. Our project compared clinical hypovolemia (CH) with three diagnostic adjuncts: 1) noninvasive cardiac output monitoring (NICOM), 2) ultrasound (US) static IVC collapsibility (US-IVC), and 3) US dynamic carotid upstroke velocity (US-C). We hypothesized US measures would correlate more closely to CH than NICOM.

METHODS

Adult trauma/surgical intensive care unit patients were prospectively screened for suspected hypovolemia after acute resuscitation, excluding patients with burns, known heart failure, or severe liver/kidney disease. Adjunct measurements were assessed up to twice a day until clinical improvement. Hypovolemia was defined as: 1) NICOM: ≥10% stroke volume variation with passive leg raise, 2) US-IVC: <2.1 cm and >50% collapsibility (nonventilated) or >18% collapsibility (ventilated), 3) US-C: peak systolic velocity increase 15 cm/s with passive leg raise. Previously unknown cardiac dysfunction seen on US was noted. Observation-level data were analyzed with a Cohen's kappa (κ).

RESULTS

44 patients (62% male, median age 60) yielded 65 measures. Positive agreement with CH was 47% for NICOM, 37% for US-IVC and 10% for US-C. None of the three adjuncts correlated with CH (κ -0.045 to 0.029). After adjusting for previously unknown cardiac dysfunction present in 10 patients, no adjuncts correlated with CH (κ -0.036 to 0.031). No technique correlated with any other (κ -0.118 to 0.083).

CONCLUSIONS

None of the adjunct measurements correlated with CH or each other, highlighting that fluid status assessment remains challenging in critical care. US should assess for right ventricular dysfunction prior to resuscitation.

Point-of-Care Echocardiography in the Difficult-to-Image Patient in the ICU: A Narrative Review

OBJECTIVES

The objective of this narrative review was to address common obstacles encountered in the ICU to acquiring quality and interpretable images using point-of-care echocardiography.

DATA SOURCES

Detailed searches were performed using PubMed and Ovid Medline using medical subject headings and keywords on topics related to patient positioning, IV echo contrast, alternative subcostal views, right ventricular outflow tract (RVOT) hemodynamics, and point-of-care transesophageal echocardiography. Articles known to the authors were also selected based on expert opinion.

STUDY SELECTION

Articles specific to patient positioning, IV echo contrast, alternative subcostal views, RVOT hemodynamics, and point-of-care transesophageal echocardiography were considered.

DATA EXTRACTION

One author screened titles and extracted relevant data while two separate authors independently reviewed selected articles.

DATA SYNTHESIS

Impediments to acquiring quality and interpretable images in critically ill patients are common. Notably, body habitus, intra-abdominal hypertension, dressings or drainage tubes, postoperative sternotomies, invasive mechanical ventilation, and the presence of subcutaneous emphysema or lung hyperinflation are commonly encountered obstacles in transthoracic image acquisition in the ICU. Despite these obstacles, the bedside clinician may use obstacle-specific maneuvers to enhance image acquisition. These may include altering patient positioning, respiratory cycle timing, expanding the subcostal window to include multilevel short-axis views for use in the assessment of RV systolic function and hemodynamics, coronal transhepatic view of the inferior vena cava, and finally point-of-care transesophageal echocardiography.

CONCLUSIONS

Despite common obstacles to point-of-care echocardiography in critically ill patients, the beside sonographer may take an obstacle-specific stepwise approach to enhance image acquisition in difficult-to-image patients.

Higher portal venous pulsatility is associated with worse clinical outcomes following congenital heart surgery: a single-centre prospective cohort study

PURPOSE

Increased portal venous flow pulsatility is associated with major complications after adult cardiac surgery. Nevertheless, no data are available for pediatric patients with congenital heart disease. We hypothesized that Doppler parameters including portal flow pulsatility could be associated with postoperative outcomes in children undergoing various cardiac surgeries.

METHODS

We conducted a prospective observational cohort study in children undergoing congenital cardiac surgery. We obtained postoperative portal, splenic, and hepatic venous Doppler data and perioperative clinical data including major postoperative complications. Portal and splenic venous flow pulsatility were calculated. We evaluated the association between venous Doppler parameters and adverse outcomes. The primary objective was to determine whether postoperative portal flow pulsatility could indicate major complications following congenital heart surgery.

RESULTS

In this study, we enrolled 389 children, 74 of whom experienced major postoperative complications. The mean (standard deviation) portal pulsatility (44 [30]% vs 25 [14]%; 95% confidence interval [CI] for mean difference, 12 to 26; P < 0.001] and splenic pulsatility indices (41 [30]% vs 26 [16]%; 95% CI, 7 to 23; P < 0.001) were significantly higher in children with postoperative complications than in those without complications. The portal pulsatility index was able to help identify postoperative complications in biventricular patients and univentricular patients receiving bidirectional cavopulmonary shunt whereas it did not in other univentricular patients. An increased postoperative portal pulsatility index was significantly associated with major complications after pediatric cardiac surgery (odds ratio, 1.40; 95% CI, 1.29 to 1.91; P < 0.001).

CONCLUSIONS

Higher portal venous pulsatility is associated with major postoperative complications in children undergoing cardiac surgery. Nevertheless, more data are needed to conclude the efficacy of portal venous pulsatility in patients with univentricular physiology.

STUDY REGISTRATION

ClinicalTrials.gov (NCT03990779); registered 19 June 2019.

Internal jugular vein collapsibility does not predict fluid responsiveness in spontaneously breathing patients after cardiac surgery

PURPOSE

The objective of our study was to evaluate the diagnostic accuracy of internal jugular vein (IJV) collapsibility as a predictor of fluid responsiveness in spontaneously breathing patients after cardiac surgery.

METHODS

In this prospective observational study, spontaneously breathing patients were enrolled on the first postoperative day after coronary artery bypass grafting. Hemodynamic data coupled with simultaneous ultrasound assessment of the IJV were collected at baseline and after passive leg raising test (PLR). Continuous cardiac index (CI), stroke volume (SV), and stroke volume variation (SVV) were assessed with FloTracTM/EV1000™. Fluid responsiveness was defined as an increase in CI ≥ 10% after PLR. We compared the differences in measured variables between fluid responders and non-responders and tested the ability of ultrasonographic IJV indices to predict fluid responsiveness.

RESULTS

Fifty-four patients were included in the study. Seventeen (31.5%) were fluid responders. The responders demonstrated significantly lower inspiratory and expiratory diameters of the IJV at baseline, but IJV collapsibility was comparable (P = 0.7). Using the cut-off point of 20%, IJV collapsibility predicted fluid responsiveness with a sensitivity of 76.5% and specificity of 38.9%, ROC AUC 0.55.

CONCLUSION

In spontaneously breathing patients after surgical coronary revascularisation, collapsibility of the internal jugular vein did not predict fluid responsiveness.

Effect of tidal volume change on pressure-based prediction of fluid responsiveness in children

INTRODUCTION

It is known that pulse pressure variation and systolic pressure variation cannot predict fluid responsiveness in children. In adults, the ability of these dynamic parameters to predict fluid responsiveness is improved by increasing tidal volume. We planned to investigate whether pulse pressure variation or systolic pressure variation can predict fluid responsiveness in children when augmented by increasing tidal volume by conducting a prospective study.

METHODS

We enrolled children younger than 7 years who underwent cardiac surgery for atrial septal defect or ventricular septal defect. After sternum closure, pulse pressure variation and systolic pressure variation were continuously recorded while changing the tidal volume to 6, 10, and 14 mL/kg. Fluid loading was done with 10 mL/kg of crystalloids for 10 min, and stroke volume index was measured via transesophageal echocardiography. Children whose stroke volume index increased by more than 15% after the fluid loading were defined as responders to fluid therapy. We set primary outcome as the predictability of pulse pressure variation and systolic pressure variation for fluid responsiveness and measured the area under the curve of receiver operating characteristics curve.

RESULTS

Twenty-six children were included, of which 15 were responders. At the tidal volume of 14 mL/kg, the area under the curves of receiver operating characteristics curves of pulse pressure variation and systolic pressure variation were 0.576 (p = .517) and 0.548 (p = .678), respectively. The differences in dynamic parameters between responders and nonresponders were not significant.

DISCUSSION

Failure of pulse pressure variation or systolic pressure variation at augmented tidal volume in children may be due to difference in their arterial compliance from those of adults. Large compliance of thoracic wall may be another reason.

CONCLUSIONS

Augmented pulse pressure variation or systolic pressure variation due to increased tidal volume cannot predict fluid responsiveness in children after simple cardiac surgery.

Cirrhotic cardiomyopathy influences clinical outcomes and enhances performance of conventional risk prediction models in acute-on-chronic liver failure with severe sepsis

BACKGROUND

Point-of-care echocardiography (POC-Echo) is an essential intensive care hemodynamic monitoring tool.

AIMS

To assess POC-Echo parameters [i.e., cardiac index (CI), systemic vascular resistance index (SVRI) and cirrhotic cardiomyopathy (CCM) markers] and serum biomarkers in predicting circulatory failure (need for vasopressors) and mortality in patients with acute-on-chronic liver failure (ACLF) having sepsis-induced hypotension.

METHODS

We performed serial POC-Echo within 6 hours (h) of presentation and subsequently at 24, 48 and 72 h in patients with ACLF and sepsis-induced hypotension admitted to our liver intensive care unit. Clinical data, POC-Echo data and serum biomarkers were collected prospectively.

RESULTS

We enrolled 120 patients [59% men, aged 49 ± 12 years, 56% alcohol-related disease and median MELDNa of 30 (27-32)], of whom 68 (56.6%) had circulatory failure, with overall mortality of 60%. CCM was present in 52.5%. The predictors of circulatory failure were CI (aHR -1.5; p = 0.021), N-terminal brain natriuretic peptide (aHR -1.1; p = 0.007) and CCM markers; e' septal mitral velocity (aHR -0.5; p = 0.039) and E/e' ratio (aHR -1.2; p = 0.045). Reduction in CI by 20% and SVRI by 15% at 72 h predicted mortality with a sensitivity of 84% and 72%, and specificity 76% and 65%, respectively (p < 0.001). The MELD-CCM model and CLIF-CCM model were computed as MELDNa + 1.815 × E/e' (septal) + 0.402 × e' (septal) and CLIF-C ACLF + 1.815 × E/e' (septal) + 0.402 × e' (septal), respectively, based on multivariable logistic regression. Both scores outperformed MELDNa (z-score = -2.073, p = 0.038) and CLIF-C ACLF score (z score = -2.683, p-value = 0.007), respectively, in predicting 90-day mortality.

CONCLUSION

POC-Echo measurements such as CCM markers (E/e' and e' velocity) and change in CI reliably predict circulatory failure and mortality in ACLF with severe sepsis. CCM markers significantly enhanced the CLIF-C ACLF and MELDNa predictive performance.

Reliability of point-of-care ultrasound to evaluate fluid tolerance performed by critical care residents

BACKGROUND

Patients with hypotension usually receive intravenous fluids, but only 50% will respond to fluid administration. We aimed to assess the intra and interobserver agreement to evaluate fluid tolerance through diverse ultrasonographic methods.

METHODS

We prospectively included critically ill patients on mechanical ventilation. One trained intensivist and two intensive care residents obtained the left ventricular outflow tract velocity-time integral (VTI) variability, inferior vena cava (IVC) distensibility index, internal jugular vein (IJV) distensibility index, and each component of the venous excess ultrasound (VExUS) system. We obtained the intraclass correlation coefficient (ICC) and Gwet's first-order agreement coefficient (AC1), as appropriate.

RESULTS

We included 32 patients. In-training observers were unable to assess the VTI-variability in two patients. The interobserver agreement was moderate to evaluate the IJV-distensibility index (AC1 0.54, CI 95% 0.29-0.80), fair to evaluate VTI-variability (AC1 0.39, CI 95% 0.12-0.66), and absent to evaluate the IVC-distensibility index (AC1 0.19, CI 95% - 0.07 to 0.44). To classify patients according to their VExUS grade, the intraobserver agreement was good, and the interobserver agreement was moderate (AC1 0.52, CI 95% 0.34-0.69).

CONCLUSIONS

Point-of-care ultrasound is frequently used to support decision-making in fluid management. However, we observed that the VTI variability and IVC-distensibility index might require further training of the ultrasound operators to be clinically useful. Our findings suggest that the IJV-distensibility index and the VExUS system have acceptable reproducibility among in-training observers.

Objective Methods of Assessing Fluid Status to Optimize Volume Management in Kidney Disease and Hypertension: The Importance of Ultrasound

Fluid overload, a prevalent complication in patients with renal disease and hypertension, significantly impacts patient morbidity and mortality. The daily clinical challenges that clinicians face include how to identify fluid overload early enough in the course of the disease to prevent adverse outcomes and to guide and potentially reduce the intensity of the diuresis. Traditional methods for evaluating fluid status, such as pitting edema, pulmonary crackles, or chest radiography primarily assess extracellular fluid and do not accurately reflect intravascular volume status or venous congestion. This review explores the rationale, mechanism, and evidence behind more recent methods used to assess volume status, namely, lung ultrasound, inferior vena cava (IVC) ultrasound, venous excess ultrasound score, and basic and advanced cardiac echocardiographic techniques. These methods offer a more accurate and objective assessment of fluid status, providing real-time, non-invasive measures of intravascular volume and venous congestion. The methods we discuss are primarily used in inpatient settings, but, given the increased pervasiveness of ultrasound technology, some could soon expand to the outpatient setting.

Processing Ultrasound Scans of the Inferior Vena Cava: Techniques and Applications

The inferior vena cava (IVC) is the largest vein in the body. It returns deoxygenated blood to the heart from the tissues placed under the diaphragm. The size and dynamics of the IVC depend on the blood volume and right atrial pressure, which are important indicators of a patient's hydration and reflect possible pathological conditions. Ultrasound (US) assessment of the IVC is a promising technique for evaluating these conditions, because it is fast, non-invasive, inexpensive, and without side effects. However, the standard M-mode approach for measuring IVC diameter is prone to errors due to the vein movements during respiration. B-mode US produces two-dimensional images that better capture the IVC shape and size. In this review, we discuss the pros and cons of current IVC segmentation techniques for B-mode longitudinal and transverse views. We also explored several scenarios where automated IVC segmentation could improve medical diagnosis and prognosis.

Role of Inferior Vena Cava Collapsibility Index in the Prediction of Hypotension Associated With Central Neuraxial Block: A Prospective Observational Study

BACKGROUND

There are only a few studies on perioperative use of inferior vena cava collapsibility index (IVCCI) to predict hypotension after anesthesia. The study aimed to evaluate IVCCI as predictor of hypotension in patients receiving central neuraxial block (CNB) for elective surgery.

METHOD

One hundred patients of ASA grade I/II, aged 18-60 years undergoing elective surgery under CNB were enrolled. Ultrasound IVC examination was performed preoperatively and the patients were allocated to Group C (Collapsing group: IVCCI ≥50%) or Group NC (Non-Collapsing group: IVCCI <50%). Thereafter, in the operation theatre, the patient was given CNB and observed for development of hypotension. The hypotension was treated with additional fluid bolus (5 mL kg-1 over 10 minutes) and/or vasopressor (mephentramine 6 mg IV). The primary objective was to compare the incidence of hypotension; the secondary objective was to compare the fluid and vasopressor requirement in the Groups C and NC.

RESULT

Six patients were excluded from study due to poor visualization of IVC. The mean IVCCI for Group C (n = 53) was 56.06 ± 4.62% and Group NC (n = 41) was 34.01 ± 8.94%. The incidence of hypotension was 56.60% (20/53) in Group C and 4.87% (2/41) in Group NC (P < .001). The vasopressor and fluid requirement was also statistically significantly higher in Group C compared with Group NC (P < .001).

CONCLUSION

Preoperative ultrasound assessment of IVCCI is useful in predicting hypotension after CNB in patients receiving CNB for elective surgery.

Subcostal versus right lateral ultrasound measurements of inferior vena cava: Measurements obtained from these two views are not equivalent in non-ICU patients

Objective

The objective of this study is to assess concordance between the subcostal and right lateral view for ultrasonographic inferior vena cava measurements including the end-inspiratory diameter, end-expiratory diameter and respiratory variation represented by the caval index in spontaneously breathing healthy adults.

Methods

We recruited a convenience sample of 33 healthy adults. A phased array ultrasound probe was used to obtain inferior vena cava measurements from a subcostal view in the sagittal plane and from a right lateral view in the coronal plane with B-mode ultrasound. End-inspiratory diameter, end-expiratory diameter and caval index were obtained for each view. A two-tailed t-test was performed to compare the caval indices obtained by the two views. Bland-Altman analysis was used to obtain the limits of agreement for the inferior vena cava diameter and caval index across the two views.

Results

Subcostal and right lateral caval indices across all participants were significantly different according to a paired t-test (p < 0.0001). The Bland-Altman analysis showed wide limits of agreement in end-inspiratory diameter (-0.97 and 0.50 cm) and in end-expiratory diameter (-0.94 and 0.90 cm). The right lateral view underestimated the inferior vena cava caval index relative to the subcostal view.

Conclusions

The subcostal and right lateral views are not equivalent in obtaining inferior vena cava measurements in spontaneously breathing healthy adults. Current cut-off values for measurement-based applications of inferior vena cava ultrasound, including fluid responsiveness using caval indices, may not be accurate when values are obtained from the right lateral view in the coronal plane of the inferior vena cava in patients.

Inferior vena cava distensibility from subcostal and trans-hepatic imaging using both M-mode or artificial intelligence: a prospective study on mechanically ventilated patients

BACKGROUND

Variation of inferior vena cava (IVC) is used to predict fluid-responsiveness, but the IVC visualization with standard sagittal approach (SC, subcostal) cannot be always achieved. In such cases, coronal trans-hepatic (TH) window may offer an alternative, but the interchangeability of IVC measurements in SC and TH is not fully established. Furthermore, artificial intelligence (AI) with automated border detection may be of clinical value but it needs validation.

METHODS

Prospective observational validation study in mechanically ventilated patients with pressure-controlled mode. Primary outcome was the IVC distensibility (IVC-DI) in SC and TH imaging, with measurements taken both in M-Mode or with AI software. We calculated mean bias, limits of agreement (LoA), and intra-class correlation (ICC) coefficient.

RESULTS

Thirty-three patients were included. Feasibility rate was 87.9% and 81.8% for SC and TH visualization, respectively. Comparing imaging from the same anatomical site acquired with different modalities (M-Mode vs AI), we found the following IVC-DI differences: (1) SC: mean bias - 3.1%, LoA [- 20.1; 13.9], ICC = 0.65; (2) TH: mean bias - 2.0%, LoA [- 19.3; 15.4], ICC = 0.65. When comparing the results obtained from the same modality but from different sites (SC vs TH), IVC-DI differences were: (3) M-Mode: mean bias 1.1%, LoA [- 6.9; 9.1], ICC = 0.54; (4) AI: mean bias 2.0%, LoA [- 25.7; 29.7], ICC = 0.32.

CONCLUSIONS

In patients mechanically ventilated, AI software shows good accuracy (modest overestimation) and moderate correlation as compared to M-mode assessment of IVC-DI, both for SC and TH windows. However, precision seems suboptimal with wide LoA. The comparison of M-Mode or AI between different sites yields similar results but with weaker correlation. Trial registration Reference protocol: 53/2022/PO, approved on 21/03/2022.

Role of Point-of-Care Ultrasound in Emergency Airway Management Outside the Operating Room

Tracheal intubation is one of the most frequently performed procedures in critically ill patients, and is associated with significant morbidity and mortality. Hemodynamic instability and cardiovascular collapse are common complications associated with the procedure, and are likely in patients with a physiologically difficult airway. Bedside point-of-care ultrasound (POCUS) can help identify patients with high risk of cardiovascular collapse, provide opportunity for hemodynamic and respiratory optimization, and help tailor airway management plans to meet individual patient needs. This review discusses the role of POCUS in emergency airway management, provides an algorithm to facilitate its incorporation into existing practice, and provides a framework for future studies.

Predictors of fluid responsiveness in the operating room: a narrative review

Prediction of fluid responsiveness has been considered an essential tool for modern fluid management. However, most studies in this field have focused on patients in intensive care unit despite numerous research throughout several decades. Therefore, the present narrative review aims to show the representative method's feasibility, advantages, and limitations in predicting fluid responsiveness, focusing on the operating room environments. Firstly, we described the predictors of fluid responsiveness based on heart-lung interaction, including pulse pressure and stroke volume variations, the measurement of respiratory variations of inferior vena cava diameter, and the end-expiratory occlusion test and addressed their limitations. Subsequently, the passive leg raising test and mini-fluid challenge tests were also mentioned, which assess fluid responsiveness by mimicking a classic fluid challenge. In the last part of this review, we pointed out the pitfalls of fluid management based on fluid responsiveness prediction, which emphasized the importance of individualized decision-making. Understanding the available representative methods to predict fluid responsiveness and their associated benefits and drawbacks through this review will aid anesthesiologists in choosing the most reliable methods for optimal fluid administration in each patient during anesthesia in the operating room.

Usefulness of the velocity-time integral of the left ventricular outflow tract variability index to predict fluid responsiveness in patients undergoing cardiac surgery

BACKGROUND

Haemodynamic monitoring of patients after cardiac surgery using echocardiographic evaluation of fluid responsiveness is both challenging and increasingly popular. We evaluated fluid responsiveness in the first hours after surgery by determining the variability of the velocity-time integral of the left ventricular outflow tract (VTI-LVOT).

METHODS

We conducted a cross-sectional study of 50 consecutive adult patients who underwent cardiac surgery and in whom it was possible to obtain VTI-LVOT measurements. We then determined the variability and correlations with our pulse pressure variation (PPV) measurements to predict fluid responsiveness.

RESULTS

A strong positive correlation was seen between the VTI-LVOT variability index absolute values and PPV for predicting fluid responsiveness in the first hours after cardiac surgery. We also found that the VTI-LVOT variability index has high specificity and a high positive likelihood ratio compared with the gold standard using a cut-off point of ≥ 12%.

CONCLUSIONS

The VTI-LVOT variability index is a valuable tool for determining fluid responsiveness during the first 6 postoperative hours in patients undergoing cardiac surgery.

A preoperative ultrasound-based protocol for optimisation of fluid therapy to prevent early intraoperative hypotension: a randomised controlled study

BACKGROUND

Intraoperative hypotension is a risk factor for postoperative complications. Preoperative dehydration is a major contributor, although it is difficult to estimate its severity. Point-of-care ultrasound offers several potential methods, including measurements of the inferior vena cava. The addition of lung ultrasound may offer a safety limit. We aimed to evaluate whether the implication of an ultrasound-based preoperative fluid therapy protocol can decrease the incidence of early intraoperative hypotension.

METHODS

Randomised controlled study in a tertiary university department involves elective surgical patients of ASA 2-3 class, scheduled for elective major abdominal surgery under general anaesthesia with intubation. We randomised 40-40 patients; 38-38 were available for analysis. Conventional fluid therapy was ordered on routine preoperative visits. Ultrasound-based protocol evaluated the collapsibility index of inferior vena cava and lung ultrasound profiles. Scans were performed twice: 2 h and 30 min before surgery. A high collapsibility index (≥ 40%) indicated a standardised fluid bolus, while the anterior B-profile of the lung ultrasound contraindicated further fluid. The primary outcome was the incidence of postinduction and early intraoperative (0-10 min) hypotension (MAP < 65 mmHg and/or ≥ 30% of decrease from baseline). Secondary endpoints were postoperative lactate level, urine output and lung ultrasound score at 24 h.

RESULTS

The absolute criterion of postinduction hypotension was fulfilled in 12 patients in the conventional group (31.6%) and 3 in the ultrasound-based group (7.9%) (p = 0.0246). Based on composite criteria of absolute and/or relative hypotension, we observed 17 (44.7%) and 7 (18.4%) cases, respectively (p = 0.0136). The incidence of early intraoperative hypotension was also lower: HR for absolute hypotension was 2.10 (95% CI 1.00-4.42) in the conventional group (p = 0.0387). Secondary outcome measures were similar in the study groups.

CONCLUSION

We implemented a safe and effective point-of-care ultrasound-based preoperative fluid replacement protocol into perioperative care.

TRIAL REGISTRATION

The study was registered to ClinicalTrials.gov on 10/12/2021, registration number: NCT05171608 (registered prospectively on 10/12/2021).

Integrated ultrasonographic approach to evaluate fluid responsiveness in critically ill patients

In patients with acute circulatory failure, we tested the feasibility of the evaluation of the fluid-responsiveness (FR) by a combined approach with echocardiography and lung ultrasound. We enrolled 113 consecutive patients admitted to the Emergency Department High-Dependency Unit of Careggi University-Hospital from January 2015 to June 2020. We assessed: (1) inferior vena cava collapsibility index (IVCCI); (2) the variation of aortic flow (VTIAo) during the passive leg raising test (PLR); (3) the presence of interstitial syndrome by lung ultrasound. FR was defined as an increase in the VTIAo > 10% during PLR or IVCCI ≥ 40%. FR patients were treated with fluid and those non-FR with diuretics or vasopressors. The therapeutic strategy was reassessed after 12 h. The goal was to maintain the initial strategy. Among 56 FR patients, at lung ultrasound, 15 patients showed basal interstitial syndrome and 4 all-lung involvement. One fluid bolus was given to 51 patients. Among 57 non-FR patients, 26 patients showed interstitial syndrome at lung ultrasound (basal fields in 14, all lungs in 12). We administered diuretics to 21 patients and vasopressors to 4 subjects. We had to change the initial treatment plan in 9% non-FR patients and in 12% FR patients (p = NS). In the first 12 h after the evaluation, non-FR patients received significantly less fluids compared to those FR (1119 ± 410 vs 2010 ± 1254 ml, p < 0.001). The evaluation of the FR based on echocardiography and lung ultrasound was associated with the reduction in fluid administration for non-FR patients compared with those FR.

Evaluation of Portal, Splenic, and Hepatic Vein Flows in Children Undergoing Congenital Heart Surgery

OBJECTIVE

Little is known about changes in portal, splenic, and hepatic vein flow patterns in children undergoing congenital heart surgery. This study aimed to determine the characteristics of portal, splenic, and hepatic vein flow patterns using ultrasonography in children undergoing cardiac surgery.

DESIGN

Single-center, prospective observational study.

SETTING

Tertiary children's hospital, operating room.

PARTICIPANTS

Children undergoing cardiac surgery.

MEASUREMENT AND MAIN RESULTS

The authors obtained ultrasound data from the heart, inferior vena cava, portal, splenic, and hepatic veins before and after surgeries. In the biventricular group, which included children with atrial and ventricular septal defects and pulmonary stenosis (n = 246), the portal pulsatility index decreased from 38.7% to 25.6% (p < 0.001) after surgery. The preoperative portal pulsatility index was significantly higher in patients with pulmonary hypertension (43.3% v 27.4%; p < 0.001). In the single-ventricle group (n = 77), maximum portal vein flow velocities of Fontan patients were significantly lower (13.5 cm/s) compared with that of patients with modified Blalock-Taussig shunt (19.7 cm/s; p = 0.035) or bidirectional cavopulmonary shunt (23.1 cm/s; p < 0.001). The cardiac index was inversely correlated with the portal pulsatility index in the bidirectional cavopulmonary shunt and Fontan circulation. (β = -5.693, r² = 0.473; p = 0.001) The portal pulsatility index was correlated with splenic venous pulsatility and hepatic venous atrial reverse flow velocity in biventricular and single-ventricle groups.

CONCLUSIONS

The characteristics of venous Doppler patterns in the portal, splenic, and hepatic veins differed according to congenital heart disease. Further studies are required to determine the association between splanchnic venous Doppler findings and clinical outcomes in this population.

Assessment of the inferior vena cava collapsibility from subcostal and trans-hepatic imaging using both M-mode or artificial intelligence: a prospective study on healthy volunteers

PURPOSE

Assessment of the inferior vena cava (IVC) respiratory variation may be clinically useful for the estimation of fluid-responsiveness and venous congestion; however, imaging from subcostal (SC, sagittal) region is not always feasible. It is unclear if coronal trans-hepatic (TH) IVC imaging provides interchangeable results. The use of artificial intelligence (AI) with automated border tracking may be helpful as part of point-of-care ultrasound but it needs validation.

METHODS

Prospective observational study conducted in spontaneously breathing healthy volunteers with assessment of IVC collapsibility (IVCc) in SC and TH imaging, with measures taken in M-mode or with AI software. We calculated mean bias and limits of agreement (LoA), and the intra-class correlation (ICC) coefficient with their 95% confidence intervals.

RESULTS

Sixty volunteers were included; IVC was not visualized in five of them (n = 2, both SC and TH windows, 3.3%; n = 3 in TH approach, 5%). Compared with M-mode, AI showed good accuracy both for SC (IVCc: bias - 0.7%, LoA [- 24.9; 23.6]) and TH approach (IVCc: bias 3.7%, LoA [- 14.9; 22.3]). The ICC coefficients showed moderate reliability: 0.57 [0.36; 0.73] in SC, and 0.72 [0.55; 0.83] in TH. Comparing anatomical sites (SC vs TH), results produced by M-mode were not interchangeable (IVCc: bias 13.9%, LoA [- 18.1; 45.8]). When this evaluation was performed with AI, such difference became smaller: IVCc bias 7.7%, LoA [- 19.2; 34.6]. The correlation between SC and TH assessments was poor for M-mode (ICC = 0.08 [- 0.18; 0.34]) while moderate for AI (ICC = 0.69 [0.52; 0.81]).

CONCLUSIONS

The use of AI shows good accuracy when compared with the traditional M-mode IVC assessment, both for SC and TH imaging. Although AI reduces differences between sagittal and coronal IVC measurements, results from these sites are not interchangeable.

Inferior Vena Cava Ultrasonography for Volume Status Evaluation: An Intriguing Promise Never Fulfilled

The correct determination of volume status is a fundamental component of clinical evaluation as both hypovolaemia (with hypoperfusion) and hypervolaemia (with fluid overload) increase morbidity and mortality in critically ill patients. As inferior vena cava (IVC) accounts for two-thirds of systemic venous return, it has been proposed as a marker of volaemic status by indirect assessment of central venous pressure or fluid responsiveness. Although ultrasonographic evaluation of IVC is relatively easy to perform, correct interpretation of the results may not be that simple and multiple pitfalls hamper its wider application in the clinical setting. In the present review, the basic elements of the pathophysiology of IVC behaviour, potential applications and limitations of its evaluation are discussed.

Point-of-care ultrasonography to predict fluid responsiveness in children: A systematic review and meta-analysis

BACKGROUND

Point-of-care ultrasonography (POCUS) is proposed as a valuable method for hemodynamic monitoring and several ultrasound-based predictors of fluid responsiveness have been studied. The main objective of this study was to assess the accuracy of these predictors in children.

METHODS

PubMed, Embase, Scopus, ClinicalTrials.gov, and Cochrane Library databases were searched for relevant publications through July 2022. Pediatric studies reporting accuracy estimates of ultrasonographic predictors of fluid responsiveness were included since they had used a standard definition of fluid responsiveness and had performed an adequate fluid challenge.

RESULTS

Twenty-three studies involving 1028 fluid boluses were included, and 12 predictors were identified. A positive response to fluid infusion was observed in 59.7% of cases. The vast majority of participants were mechanically ventilated (93.4%). The respiratory variation in aortic blood flow peak velocity (∆Vpeak) was the most studied predictor, followed by the respiratory variation in inferior vena cava diameter (∆IVC). The pooled sensitivity and specificity of ∆Vpeak were 0.84 (95% CI, 0.76-0.90) and 0.82 (95% CI, 0.75-0.87), respectively, and the area under the summary receiver operating characteristic curve (AUSROC) was 0.89 (95% CI, 0.86-0.92). The ∆IVC presented a pooled sensitivity and specificity of 0.79 (95% CI, 0.62-0.90) and 0.70 (95% CI, 0.51-0.84), respectively, and an AUSROC of 0.81 (95% CI, 0.78-0.85). Significant heterogeneity in accuracy estimates across studies was observed.

CONCLUSIONS

POCUS has the potential to accurately predict fluid responsiveness in children. However, only ∆Vpeak was found to be a reliable predictor. There is a lack of evidence supporting the use of POCUS to guide fluid therapy in spontaneously breathing children.

Circulatory shock in adults in emergency department

Circulatory shock is a common condition that carries high morbidity and mortality. This review aims to update the critical steps in managing common types of shock in adult patients admitted to medical emergency and intensive care units. A literature review was performed by searching PubMed, EMBASE Ovid, and Cochrane Library, using the following search items: ("shock" OR "circulatory shock" OR "septic shock" OR "cardiogenic shock") AND ("management" OR "treatment" OR "resuscitation"). The review emphasizes prompt shock identification with tissue hypoperfusion, knowledge of the underlying pathophysiological mechanism, initial fluid resuscitation with balanced crystalloids, norepinephrine as the preferred vasopressor in septic and profound cardiogenic shock, and tailored intervention addressing specific etiologies. Point-of-care ultrasound may help evaluate an undifferentiated shock and determine fluid responsiveness. The approach to septic shock is improving; however, confirmatory studies are required for many existing (e.g., amount of initial fluids and steroids) and emerging (e.g., angiotensin II) therapies. Knowledge gaps and wide variations persist in managing cardiogenic shock that needs urgent addressing to improve outcomes.

Cardiac function in critically ill patients with severe COVID: A prospective cross-sectional study in mechanically ventilated patients

PURPOSE

To evaluate cardiac function in mechanically ventilated patients with COVID-19.

MATERIALS AND METHODS

Prospective, cross-sectional multicenter study in four university-affiliated hospitals in Chile. All consecutive patients with COVID-19 ARDS requiring mechanical ventilation admitted between April and July 2020 were included. We performed systematic transthoracic echocardiography assessing right and left ventricular function within 24 h of intubation.

RESULTS

140 patients aged 57 ± 11, 29% female were included. Cardiac output was 5.1 L/min [IQR 4.5-6.2] and 86% of the patients required norepinephrine. ICU mortality was 29% (40 patients). Fifty-four patients (39%) exhibited right ventricle dilation out of whom 20 patients (14%) exhibited acute cor pulmonale (ACP). Eight out of the twenty patients with ACP exhibited pulmonary embolism (40%). Thirteen patients (9%) exhibited left ventricular systolic dysfunction (ejection fraction <45%). In the multivariate analysis acute cor pulmonale and PaO₂/FiO₂ ratio were independent predictors of ICU mortality.

CONCLUSIONS

Right ventricular dilation is highly prevalent in mechanically ventilated patients with COVID-19 ARDS. Acute cor pulmonale was associated with reduced pulmonary function and, in only 40% of patients, with co-existing pulmonary embolism. Acute cor pulmonale is an independent risk factor for ICU mortality.

Ultrasound-guided venous pressure measurement

Current standard technique for venous pressure measurement is still invasive, requiring insertion of a catheter. Additionally, clinical estimation of central venous pressure (CVP) has proven unreliable compared to invasive methods. Meanwhile, different non-invasive ultrasound guided modalities may provide a valid alternative to invasive venous pressure measurement. Particularly promising is a novel compression ultrasound (CUS) which combines ultrasound properties with a tissue pressure manometer enabling even further future applications. This review provides an overview using ultrasound guided non-invasive venous pressure measurement (UGPni) in clinical trials so far and focuses on three objectives: (1) To summarize the main methods using UGPni for central venous pressure measurement (2) To outline the key findings of previous clinical trials for UGPni regarding CVP measurement with primary focus on novel compression ultrasound of a forearm vein (3) To point out limitations and possible future clinical implications of these ultrasound modalities UGPni represents an easy-to-perform and safe alternative to invasive "gold standard" diagnostic tools for measuring central venous pressure. After a brief introduction, non-specialist personnel using a portable ultrasound device can apply this method in a feasible way. Of all mentioned methods in this review CUS is the method of choice underscoring its ability to assess a patient's CVP categories correctly. Furthermore, detection of non-invasive central venous pressure in the emergency room represents an independent predictor for cardiac rehospitalization in patients with decompensated heart failure, thus helping in risk stratification as well as being an additive tool in general hemodynamic management of critically ill patients. This review concludes a significant role for ultrasound guided non-invasive venous pressure measurement suitable for a wide range of everyday clinical practice. However, further studies are warranted to proof a causal relationship in this regard.

How can assessing hemodynamics help to assess volume status?

In critically ill patients, fluid infusion is aimed at increasing cardiac output and tissue perfusion. However, it may contribute to fluid overload which may be harmful. Thus, volume status, risks and potential efficacy of fluid administration and/or removal should be carefully evaluated, and monitoring techniques help for this purpose. Central venous pressure is a marker of right ventricular preload. Very low values indicate hypovolemia, while extremely high values suggest fluid harmfulness. The pulmonary artery catheter enables a comprehensive assessment of the hemodynamic profile and is particularly useful for indicating the risk of pulmonary oedema through the pulmonary artery occlusion pressure. Besides cardiac output and preload, transpulmonary thermodilution measures extravascular lung water, which reflects the extent of lung flooding and assesses the risk of fluid infusion. Echocardiography estimates the volume status through intravascular volumes and pressures. Finally, lung ultrasound estimates lung edema. Guided by these variables, the decision to infuse fluid should first consider specific triggers, such as signs of tissue hypoperfusion. Second, benefits and risks of fluid infusion should be weighted. Thereafter, fluid responsiveness should be assessed. Monitoring techniques help for this purpose, especially by providing real time and precise measurements of cardiac output. When decided, fluid resuscitation should be performed through fluid challenges, the effects of which should be assessed through critical endpoints including cardiac output. This comprehensive evaluation of the risk, benefits and efficacy of fluid infusion helps to individualize fluid management, which should be preferred over a fixed restrictive or liberal strategy.

Association between transoesophageal echocardiography monitoring indicators and the incidence of postoperative acute kidney injury in coronary artery bypass grafting: a study protocol for a prospective multicenter cohort study

INTRODUCTION

Previous studies on transoesophageal echocardiography in coronary artery bypass grafting mainly focused on whether to change the surgical plan rather than improve the clinical prognosis. Currently, there are sparse studies on the relationship between transoesophageal echocardiography indicators and the prognosis of patients undergoing coronary artery bypass grafting. The primary aim of this study is to explore the association between transoesophageal echocardiography monitoring indicators the respiratory variability of inferior vena cava diameter, tricuspid annular plane systolic excursion and the incidence of acute kidney injury in coronary artery bypass grafting patients.

METHODS AND ANALYSIS

We designed this prospective multicenter cohort study, which included approximately 150 adult patients (≥18 years) undergoing elective coronary artery bypass surgery. Different hospitals will be assessed to obtain information on the prevalence, risk factors, management strategies and outcomes in coronary artery bypass surgery. The cohort will be followed after the coronary artery bypass surgery period, up to 30 days after enrolment. The incidence of postoperative acute kidney injury and baseline data will be presented by descriptive statistics. We will use Freidman inspection and multivariable logistic regression to assess the association between transoesophageal echocardiography monitoring indicators and the incidence of acute kidney injury in coronary artery bypass grafting patients.

ETHICS AND DISSEMINATION

The study has been approved by the ethics committee of Shandong Provincial Qianfoshan Hospital, China (approval number: YXLL-KY-2021(067)). This is an observational study that poses no risk to the patients. All participants will obtain informed consent according to the ethics committee before patient enrolment. Funding sources will have no influence on data handling, analyses or writing of the manuscript. The article is planned for submission in an international peer-reviewed journal.

TRIAL REGISTRATION NUMBER

NCT05139108.

Artificial intelligence (AI) versus expert: A comparison of left ventricular outflow tract velocity time integral (LVOT-VTI) assessment between ICU doctors and an AI tool

PURPOSE

The application of point of care ultrasound (PoCUS) in medical education is a relatively new course. There are still great differences in the existence, quantity, provision, and depth of bedside ultrasound education. The left ventricular outflow tract velocity time integral (LVOT-VTI) has been successfully used in several studies as a parameter for hemodynamic management of critically ill patients, especially in the evaluation of fluid responsiveness. While LVOT-VTI has been broadly used, valuable applications using artificial intelligence (AI) in PoCUS is still limited. We aimed to identify the degree of correlation between auto LVOT-VTI and the manual LVOT-VTI acquired by PoCUS trained ICU doctors.

METHODS

Among the 58 ICU doctors who attended PoCUS training from 1 September 2019 to 30 November 2020, 46 ICU doctors who trained for more than 3 months were enrolled. At the end of PoCUS training, each of the enrolled ICU doctors acquired echocardiography parameters of a new ICU patient in 2 h after new patient was admitted. One of the two bedside expert sonographers would take standard echocardiogram of new ICU patients within 24 h. For ICU doctors, manual LVOT-VTI was obtained for reference and auto LVOT-VTI was calculated instantly by using an AI software tool. Based on the image quality of the auto LVOT-VTI, ICU patients was separated into ideal group (n = 31) and average group (n = 15).

RESULTS

Left ventricular end-diastolic dimension (LVEDd, p = 0.1028), left ventricular ejection fraction (LVEF, p = 0.3251), left atrial dimension (LA-d, p = 0.0962), left ventricular E/A ratio (p = 0.160), left ventricular wall motion (p = 0.317) and pericardial effusion (p = 1) had no significant difference between trained ICU doctors and expert sonographer. ICU patients in average group had greater sequential organ failure assessment (SOFA) score (7.33 ± 1.58 vs. 4.09 ± 0.57, p = 0.022) and lactic acid (3.67 ± 0.86 mmol/L vs. 1.46 ± 0.12 mmol/L, p = 0.0009) with greater value of LVEDd (51.93 ± 1.07 vs. 47.57 ± 0.89, p = 0.0053), LA-d (39.06 ± 1.47 vs. 35.22 ± 0.98, p = 0.0334) and percentage of decreased wall motion (p = 0.0166) than ideal group. There were no significant differences of δLVOT-VTI (|manual LVOT-VTI - auto LVOT-VTI|/manual VTI*100%) between the two groups (8.8% ± 1.3% vs. 10% ± 2%, p = 0.6517). Statistically, significant correlations between manual LVOT-VTI and auto LVOT-VTI were present in the ideal group (R2  = 0.815, p = 0.00) and average group (R2  = 0.741, p = 0.00).

CONCLUSIONS

ICU doctors could achieve the satisfied level of expertise as expert sonographers after 3 months of PoCUS training. Nearly two thirds of the enrolled ICU doctors could obtain the ideal view and one third of them could acquire the average view. ICU patients with higher SOFA scores and lactic acid were less likely to acquire the ideal view. Manual and auto LVOT-VTI had statistically significant agreement in both ideal and average groups. Auto LVOT-VTI in ideal view was more relevant with the manual LVOT-VTI than the average view. AI might provide real-time guidance among novice operators who lack expertise to acquire the ideal standard view.

Correlation between transhepatic and subcostal inferior vena cava ultrasonographic images for evaluating fluid responsiveness after cardiac surgery

BACKGROUND

Echocardiographic monitoring during the postoperative period following cardiac surgery is essential because patients often develop hemodynamic instability from hypovolemia and other causes. Therefore, predicting fluid responsiveness by measuring respirophasic variation in the inferior vena cava (IVC) is essential in this population. Yet it is not always possible to evaluate using the traditional subcostal view.

METHODS

This cross-sectional study of 36 consecutive adult patients who underwent cardiac surgery included those in whom it was possible to adequately visualize the IVC in both the subcostal and transhepatic views. The maximum and minimum diameters and respirophasic variation were measured in each view. These views were then correlated and the capacity of the transhepatic view to predict fluid responsiveness was evaluated.

RESULTS

There was a strong positive correlation between IVC maximum and minimum diameters and respirophasic variation according to subcostal and transhepatic views. Evaluation of IVC respirophasic variation indices using the transhepatic view also showed high sensitivity for predicting fluid responsiveness.

CONCLUSION

There is a correlation between the transhepatic and subcostal views for determining maximum and minimum IVC diameters, and distensibility and variability indices for predicting fluid responsiveness in postoperative cardiac surgery patients.

Association of inferior vena cava diameter ratio with outcomes in patients with gastrointestinal bleeding

Objective

To examine the association of inferior vena cava (IVC) diameter ratio measured using computed tomography with outcomes in patients with gastrointestinal bleeding (GIB).

Methods

A single-center retrospective observational study was conducted on consecutive patients with GIB who presented to the emergency department. The IVC diameter ratio was calculated by dividing the maximum transverse and anteroposterior diameters perpendicular to it. The association of the IVC diameter ratio with outcomes was examined using multivariable logistic regression analysis. The primary outcome was in-hospital mortality. The area under the receiver operator characteristic curve (AUC) of the IVC diameter ratio was calculated, and the sensitivity and specificity, including the cutoff values, were computed.

Results

In total, 585 patients were included in the final analysis. The in-hospital mortality rate was 4.6% (n=27). The IVC diameter ratio was significantly associated with higher in-hospital mortality in multivariable logistic regression analysis (odds ratio, 1.793; 95% confidence interval [CI], 1.239–2.597; P=0.002). The AUC of the IVC diameter ratio for in-hospital mortality was 0.616 (95% CI, 0.498–0.735). With a cutoff of the IVC diameter ratio (≥2.1), the sensitivity and specificity for predicting in-hospital mortality were 44% (95% CI, 26%–65%) and 71% (95% CI, 67%–75%), respectively.

Conclusion

The IVC diameter ratio was independently associated with in-hospital mortality in patients with GIB. However, the AUC of the IVC diameter ratio for in-hospital mortality was low.