Venous Congestion Assessed by Venous Excess Ultrasound (VExUS) and Acute Kidney Injury in Children with Right Ventricular Dysfunction.

Background: Right ventricular dysfunction (RVD) is a complication following congenital cardiac surgery in children and can lead to systemic venous congestion, low cardiac output, and organ dysfunction. Venous congestion can be transmitted backwards and adversely affect encapsulated organs such as the kidneys. Primary objective: To investigate the association between systemic venous congestion, as estimated by Venous Excess Ultrasound (VExUS), and the occurrence of acute kidney injury (AKI) in children with RVD following congenital heart surgery. Secondary objectives included comparing changes in VExUS scores after initiating treatment for RVD and venous congestion. Methods and results: This was a prospective observational study in children with RVD. The VExUS study was performed on day 1, day 2, and day 3 and categorized as VExUS-1, VExUS-2, and VExUS-3. Among 43 patients with RVD and dilated inferior vena cava, 19/43 (44%), 10/43 (23%), and 12/43 (28%) were VExUS-2 and VExUS-3, respectively. There was an association between severe RVD and elevated pulmonary artery systolic pressures and a VExUS score >2. A significant association was observed between central venous pressure (CVP) measurements and VExUS. Among 31 patients with a high VExUS score >2, 18 (58%) had AKI. Additionally, improvement in CVP and fluid balance was associated with improving VExUS scores following targeted treatment for RVD. Conclusion: VExUS serves as a valuable bedside tool for diagnosing and grading venous congestion through ultrasound Doppler. An elevated VExUS score was associated with the occurrence of AKI, and among the components of VExUS, portal vein pulsatility may be useful as a predictor of AKI. How to cite this article: Natraj R, Bhaskaran AK, Rola P, Haycock K, Siuba MTT, Ranjit S. Venous Congestion Assessed by Venous Excess Ultrasound (VExUS) and Acute Kidney Injury in Children with Right Ventricular Dysfunction. Indian J Crit Care Med 2024;28(5):447-452.

Diagnostic accuracy of venous system ultrasound for subtypes of acute kidney injury.

BACKGROUND: Management of acute kidney injury (AKI) in the ED can be difficult due to uncertainty regarding the aetiology. This study investigated the diagnostic value of venous system ultrasound for determining the aetiological subtypes of AKI in the ED. METHODS: This multidisciplinary prospective cohort study was conducted in a single academic ED over the course of a year. Adult patients with AKI were evaluated using the venous excess ultrasound (VExUS) score, which is a four-step ultrasound protocol. The protocol begins with the inferior vena cava (IVC) measurement and examines organ flow patterns, including portal, hepatic and renal veins in the presence of dilated IVC. The AKI subtypes (hypovolaemia, cardiorenal, systemic vasodilatation and renal) were adjudicated by nephrologists and emergency physicians, considering data that became available during the hospitalisation. We determined the diagnostic test characteristics of VExUS for identifying each of the four AKI aetiological subtypes. RESULTS: 150 patients with AKI were included in the study. Hypovolaemia was the most frequent finally adjudicated cause of AKI (66%), followed by cardiorenal (18%), systemic vasodilatation (8.7%) and renal (7.3%). In diagnosing the cardiorenal subtype, the area under the curve (AUC) for VExUS grade >0 was 0.819, with 77.8% sensitivity and 80.5% specificity, and the AUC for IVC maximum diameter >20.4 mm was 0.865, with 74.1% sensitivity and 86.2% specificity. For the hypovolaemia subtype, the AUC for VExUS grade ≤0 was 0.711, with 83.8% sensitivity and 56.9% specificity, and the AUC for IVC maximum diameter ≤16.8 mm was 0.736, with 73.7% sensitivity and 68.6% specificity. None of the parameters achieved adequate test characteristics for renal and systemic vasodilatation subtypes. CONCLUSION: The VExUS score has good diagnostic accuracy for cardiorenal AKI and fair accuracy for hypovolaemic AKI but cannot identify renal and systemic vasodilatation subtypes. It should not therefore be used in isolation to determine the cause of AKI in the ED. TRIAL REGISTRATION NUMBER: NCT04948710.

Simultaneous Venous-Arterial Doppler Ultrasound During Early Fluid Resuscitation to Characterize a Novel Doppler Starling Curve: A Prospective Observational Pilot Study.

Background: The likelihood of a patient being preload responsive-a state where the cardiac output or stroke volume (SV) increases significantly in response to preload-depends on both cardiac filling and function. This relationship is described by the canonical Frank-Starling curve. Research Question: We hypothesize that a novel method for phenotyping hypoperfused patients (ie, the "Doppler Starling curve") using synchronously measured jugular venous Doppler as a marker of central venous pressure (CVP) and corrected flow time of the carotid artery (ccFT) as a surrogate for SV will refine the pretest probability of preload responsiveness/unresponsiveness. Study Design and Methods: We retrospectively analyzed a prospectively collected convenience sample of hypoperfused adult emergency department (ED) patients. Doppler measurements were obtained before and during a preload challenge using a wireless, wearable Doppler ultrasound system. Based on internal jugular and carotid artery Doppler surrogates of CVP and SV, respectively, we placed hemodynamic assessments into quadrants (Qx) prior to preload augmentation: low CVP with normal SV (Q1), high CVP and normal SV (Q2), low CVP and low SV (Q3) and high CVP and low SV (Q4). The proportion of preload responsive and unresponsive assessments in each quadrant was calculated based on the maximal change in ccFT (ccFTΔ) during either a passive leg raise or rapid fluid challenge. Results: We analyzed 41 patients (68 hemodynamic assessments) between February and April 2021. The prevalence of each phenotype was: 15 (22%) in Q1, 8 (12%) in Q2, 39 (57%) in Q3, and 6 (9%) in Q4. Preload unresponsiveness rates were: Q1, 20%; Q2, 50%; Q3, 33%, and Q4, 67%. Interpretation: Even fluid naïve ED patients with sonographic estimates of low CVP have high rates of fluid unresponsiveness, making dynamic testing valuable to prevent ineffective IVF administration.

What every intensivist should know about the IVC.

Assessment of the IVC by point-of-care ultrasound in the context of resuscitation has been a controversial topic in the last decades. Most of the focus had been on its use as a surrogate marker for fluid responsiveness, with results being equivocal. We review its important anatomical aspects as well as the physiological rationale behind ultrasound assessment and propose a new way to do so, as well as explain its central role in the concept of fluid tolerance.

Inferior Vena Caval Measures Do Not Correlate with Carotid Artery Corrected Flow Time Change Measured Using a Wireless Doppler Patch in Healthy Volunteers.

(1) Background: The inspiratory collapse of the inferior vena cava (IVC), a non-invasive surrogate for right atrial pressure, is often used to predict whether a patient will augment stroke volume (SV) in response to a preload challenge. There is a correlation between changing stroke volume (SV∆) and corrected flow time of the common carotid artery (ccFT∆). (2) Objective: We studied the relationship between IVC collapsibility and ccFT∆ in healthy volunteers during preload challenges. (3) Methods: A prospective, observational, pilot study in euvolemic, healthy volunteers with no cardiovascular history was undertaken in a local physiology lab. Using a tilt-table, we studied two degrees of preload augmentation from (a) supine to 30-degrees head-down and (b) fully-upright to 30-degrees head down. In the supine position, % of IVC collapse with respiration, sphericity index and portal vein pulsatility was calculated. The common carotid artery Doppler pulse was continuously captured using a wireless, wearable ultrasound system. (4) Results: Fourteen subjects were included. IVC % collapse with respiration ranged between 10% and 84% across all subjects. Preload responsiveness was defined as an increase in ccFT∆ of at least 7 milliseconds. A total of 79% (supine baseline) and 100% (head-up baseline) of subjects were preload-responsive. No supine venous measures (including IVC % collapse) were significantly related to ccFT∆. (5) Conclusions: From head-up baseline, 100% of healthy subjects were 'preload-responsive' as per the ccFT∆. Based on the 42% and 25% IVC collapse thresholds in the supine position, only 50% and 71% would have been labeled 'preload-responsive'.

Unifying Fluid Responsiveness and Tolerance With Physiology: A Dynamic Interpretation of the Diamond-Forrester Classification.

Point of care ultrasound (POCUS) is a first-line tool to assess hemodynamically unstable patients, however, there is confusion surrounding intertwined concepts such as: "flow," "congestion," "fluid responsiveness (FR)," and "fluid tolerance." We argue that the Frank-Starling relationship is clarifying because it describes the interplay between "congestion" and "flow" on the x-axis and y-axis, respectively. Nevertheless, a single, simultaneous assessment of congestion and flow via POCUS remains a static approach. To expand this, we propose a two-step process. The first step is to place the patient on an ultrasonographic Diamond-Forrester plot. The second step is a dynamic assessment for FR (e.g., passive leg raise), which individualizes therapy across the arc of critical illness.

Bedside Ultrasound in the Management of Cardiorenal Syndromes: An Updated Review.

BACKGROUND: Cardiorenal syndromes constitute a spectrum of disorders involving heart and kidney dysfunction modulated by a complex interplay of neurohormonal, inflammatory, and hemodynamic derangements. The management of such patients often poses a diagnostic and therapeutic challenge to physicians owing to gaps in understanding of pathophysiology, paucity of objective bedside diagnostic tools, and individual biases. SUMMARY: In this narrative review, we discuss the role of clinician who performed bedside ultrasound in the management of patients with cardiorenal syndromes. Novel sonographic applications such as venous excess ultrasound score (VExUS) are reviewed in addition to the lung and focused cardiac ultrasound. Further, underrecognized causes of heart failure such as high-flow arteriovenous fistula are discussed. KEY MESSAGE: Bedside ultrasound allows a comprehensive hemodynamic characterization of cardiorenal syndromes.

Doppler identified venous congestion in septic shock: protocol for an international, multi-centre prospective cohort study (Andromeda-VEXUS).

INTRODUCTION: Venous congestion is a pathophysiological state where high venous pressures cause organ oedema and dysfunction. Venous congestion is associated with worse outcomes, particularly acute kidney injury (AKI), for critically ill patients. Venous congestion can be measured by Doppler ultrasound at the bedside through interrogation of the inferior vena cava (IVC), hepatic vein (HV), portal vein (PV) and intrarenal veins (IRV). The objective of this study is to quantify the association between Doppler identified venous congestion and the need for renal replacement therapy (RRT) or death for patients with septic shock. METHODS AND ANALYSIS: This study is a prespecified substudy of the ANDROMEDA-SHOCK 2 (AS-2) randomised control trial (RCT) assessing haemodynamic resuscitation in septic shock and will enrol at least 350 patients across multiple sites. We will include adult patients within 4 hours of fulfilling septic shock definition according to Sepsis-3 consensus conference. Using Doppler ultrasound, physicians will interrogate the IVC, HV, PV and IRV 6-12 hours after randomisation. Study investigators will provide web-based educational sessions to ultrasound operators and adjudicate image acquisition and interpretation. The primary outcome will be RRT or death within 28 days of septic shock. We will assess the hazard of RRT or death as a function of venous congestion using a Cox proportional hazards model. Sub-distribution HRs will describe the hazard of RRT given the competing risk of death. ETHICS AND DISSEMINATION: We obtained ethics approval for the AS-2 RCT, including this observational substudy, from local ethics boards at all participating sites. We will report the findings of this study through open-access publication, presentation at international conferences, a coordinated dissemination strategy by investigators through social media, and an open-access workshop series in multiple languages. TRIAL REGISTRATION NUMBER: NCT05057611.

Evaluating the Effect of Nursing-Performed Point-of-Care Ultrasound on Septic Emergency Department Patients.

Introduction Nursing-performed point-of-care ultrasound (NP-POCUS) studies have been performed on applications such as ultrasound-guided peripheral intravenous line placement and assessing bladder volume. However, research on the use of NP-POCUS in the management of septic patients remains limited. The purpose of this quality improvement study was to investigate how NP-POCUS could impact fluid treatment decisions affecting septic patients in the emergency department (ED) using a focused IVC and lung ultrasound protocol. Methods Nurses received standardized training in POCUS and performed inferior vena cava (IVC) and lung ultrasound scans on septic patients in the ED at predetermined intervals (hours: zero, three, and six). Based on their findings, they were asked to make recommendations on fluid management. Emergency physicians (EPs), both residents and attendings, are providing recommendations for fluid management without the use of ultrasound, which is being compared to the nurse-driven POCUS assessment of fluid management. EPs reviewed the NP-POCUS assessments of patient fluid status to determine nursing accuracy. Results A total of 104 patients were scanned, with a mean age of 60.7 years. EPs agreed with nursing ultrasound assessments in 99.1% of cases. Nursing ultrasound images changed management or increased physician confidence in current treatment plans 83.7% and 96.6% of the time, respectively. Before reviewing saved nursing ultrasound images, EPs underestimated fluid tolerance in 37.5% of cases, overestimated fluid tolerance in 26% of cases, and correctly estimated fluid tolerance (within 500 ml) in 36.5% of cases. Throughout resuscitation, IVCs became less collapsible, the number of cases with B-lines was essentially unchanged, and less fluid was recommended. Conclusion  This study demonstrated that nurse-performed POCUS is feasible and may have a meaningful impact on how physicians manage septic patients in the emergency department.

The effect of gravity-induced preload change on the venous excess ultrasound (VExUS) score and internal jugular vein Doppler in healthy volunteers.

BACKGROUND: The venous excess ultrasound (VExUS) score is a multi-organ Doppler approach to assess venous congestion. Despite growing use of VExUS in research and clinical practice, other veins can be visualized to assess for venous hypertension, which may overcome acquisition barriers of the VExUS exam. In this pilot, observational study, we used a wearable Doppler ultrasound to assess the relationship between jugular venous Doppler and the VExUS score under different preload conditions. We hypothesized that jugular Doppler morphology would accurately distinguish preload conditions, that it would most closely relate to the hepatic venous Doppler morphology in the fully supine position and that the VExUS score would be influenced by preload condition. RESULTS: We recruited 15 healthy volunteers with no cardiovascular history. Preload change was achieved using a tilt-table with three positions: supine, fully upright, and 30-degree head-down tilt. In each position, a VExUS score was performed; furthermore, inferior vena collapsibility and sphericity index were calculated. At the same time, jugular venous Doppler was captured by a novel, wireless, wearable ultrasound system. A continuous jugular venous Doppler morphology was 96% accurate for detecting the low preload condition. The jugular venous Doppler morphology was highly correlated with the hepatic vein, but only in the supine position. Gravitational position did not significantly affect the sphericity index or the VExUS score. CONCLUSIONS: The jugular vein Doppler morphology was able to accurately distinguish low from high preload conditions in healthy volunteers. Comparisons between VExUS Doppler morphologies and other veins should occur in the supine position when gravitational pressure gradients are minimized; finally, different preload conditions in healthy subjects did not affect the VExUS score.

Fluid management in acute kidney injury: from evaluating fluid responsiveness towards assessment of fluid tolerance.

Despite the widespread use of intravenous fluids in acute kidney injury (AKI), solid evidence is lacking. Intravenous fluids mainly improve AKI due to true hypovolaemia, which is difficult to discern at the bedside unless it is very pronounced. Empiric fluid resuscitation triggered only by elevated serum creatinine levels or oliguria is frequently misguided, especially in the presence of fluid intolerance syndromes such as increased extravascular lung water, capillary leak, intra-abdominal hypertension, and systemic venous congestion. While fluid responsiveness tests clearly identify patients who will not benefit from fluid administration (i.e. those without an increase in cardiac output), the presence of fluid responsiveness does not guarantee that fluid therapy is indicated or even safe. This review calls for more attention to the concept of fluid tolerance, incorporating it into a practical algorithm with systematic venous Doppler ultrasonography assessment to use at the bedside, thereby lowering the risk of detrimental kidney congestion in AKI.

Clinical applications of the venous excess ultrasound (VExUS) score: conceptual review and case series.

The importance of functional right ventricular failure and resultant splanchnic venous congestion has long been under-appreciated and is difficult to assess by traditional physical examination and standard diagnostic imaging. The recent development of the venous excess ultrasound score (VExUS) and growth of point-of-care ultrasound in the last decade has made for a potentially very useful clinical tool. We review the rationale for its use in several pathologies and illustrate with several clinical cases where VExUS was pivotal in clinical management.

Transthoracic Right Heart Echocardiography for the Intensivist.

BACKGROUND: The impact of critical illness on the right ventricle (RV) can be profound and RV dysfunction is associated with mortality. Intensivists are becoming more facile with bedside echocardiography, however, pedagogy has largely focused on left ventricular function. Here we review measurements of right heart function by way of echocardiographic modalities and list clinical scenarios where the RV dysfunction is a salient feature. MAIN: RV dysfunction is heterogeneously defined across many domains and its diagnosis is not always clinically apparent. The RV is affected by conditions commonly seen in the ICU such as acute respiratory distress syndrome, pulmonary embolism, RV ischemia, and pulmonary hypertension. Basic ultrasonographic modalities such as 2D imaging, M-mode, tissue Doppler, pulsed-wave Doppler, and continuous Doppler provide clinicians with metrics to assess RV function and response to therapy. CONCLUSION: The right ventricle is impacted by various critical illnesses with substantial mortality and mortality. Focused bedside echocardiographic exams with attention to the right heart may provide intensivists insight into RV function and provide guidance for patient management.

Inferring the Frank-Starling Curve From Simultaneous Venous and Arterial Doppler: Measurements From a Wireless, Wearable Ultrasound Patch.

The Frank-Starling relationship is a fundamental concept in cardiovascular physiology, relating change in cardiac filling to its output. Historically, this relationship has been measured by physiologists and clinicians using invasive monitoring tools, relating right atrial pressure (P ra) to stroke volume (SV) because the P ra-SV slope has therapeutic implications. For example, a critically ill patient with a flattened P ra-SV slope may have low P ra yet fail to increase SV following additional cardiac filling (e.g., intravenous fluids). Provocative maneuvers such as the passive leg raise (PLR) have been proposed to identify these "fluid non-responders"; however, simultaneously measuring cardiac filling and output via non-invasive methods like ultrasound is cumbersome during a PLR. In this Hypothesis and Theory submission, we suggest that a wearable Doppler ultrasound can infer the P ra-SV relationship by simultaneously capturing jugular venous and carotid arterial Doppler in real time. We propose that this method would confirm that low cardiac filling may associate with poor response to additional volume. Additionally, simultaneous assessment of venous filling and arterial output could help interpret and compare provocative maneuvers like the PLR because change in cardiac filling can be confirmed. If our hypothesis is confirmed with future investigation, wearable monitors capable of monitoring both variables of the Frank-Starling relation could be helpful in the ICU and other less acute patient settings.

Quantifying systemic congestion with Point-Of-Care ultrasound: development of the venous excess ultrasound grading system.

BACKGROUND: Organ congestion is a mediator of adverse outcomes in critically ill patients. Point-Of-Care ultrasound (POCUS) is widely available and could enable clinicians to detect signs of venous congestion at the bedside. The aim of this study was to develop several grading system prototypes using POCUS and to determine their respective ability to predict acute kidney injury (AKI) after cardiac surgery. This is a post-hoc analysis of a single-center prospective study in 145 patients undergoing cardiac surgery for which repeated daily measurements of hepatic, portal, intra-renal vein Doppler and inferior vena cava (IVC) ultrasound were performed during the first 72 h after surgery. Five prototypes of venous excess ultrasound (VExUS) grading system combining multiple ultrasound markers were developed. RESULTS: The association between each score and AKI was assessed using time-dependant Cox models as well as conventional performance measures of diagnostic testing. A total of 706 ultrasound assessments were analyzed. We found that defining severe venous congestion as the presence of severe flow abnormalities in multiple Doppler patterns with a dilated IVC (≥ 2 cm) showed the strongest association with the development of subsequent AKI compared with other combinations (HR: 3.69 CI 1.65-8.24 p = 0.001). The association remained significant after adjustment for baseline risk of AKI and vasopressor/inotropic support (HR: 2.82 CI 1.21-6.55 p = 0.02). Furthermore, this severe VExUS grade offered a useful positive likelihood ratio (+LR: 6.37 CI 2.19-18.50) when detected at ICU admission, which outperformed central venous pressure measurements. CONCLUSIONS: The combination of multiple POCUS markers may identify clinically significant venous congestion.

Can the bispectral index monitor the sedation adequacy of intubated ED adults?

The Bispectral Index Monitor (BIS) is validated as a measure of sedation depth during general anesthesia, but its value otherwise remains unclear. We hypothesized that BIS scores would correlate with standard subjective measures of assessing sedation in intubated adult ED patients and that BIS would predict inadequate sedation. Sedation was assessed by recording clinical features and by having treating physicians complete a visual analog scale (VAS; rated "not sedated" to "completely sedated") at 10, 30, and 60 minutes after intubation. Measurements of BIS were later paired with sedation assessments. Despite being statistically significant (p=.002), the correlation between BIS and VAS in our 147 paired readings was fair (Pearson's rho=-0.37) and displayed wide variability. Receiver operating characteristic curve analysis of BIS demonstrated no discriminatory power in predicting sedation adequacy (area under curve 0.53). BIS is not associated with and did not predict standard measures of sedation adequacy in intubated adults.