Inferior vena cava evaluation in fluid therapy decision making in intensive care: practical implications

Comment on Levitt et al. Approach to Decompensated Right Heart Failure in the Acute Setting. J. Clin. Med. 2024, 13, 869

We read with great interest the article titled "Approach to Decompensated Right Heart Failure in the Acute Setting" [...].

Systemic Venous Congestion Reviewed

Accurate determination of intravascular volume status is challenging in acutely ill patients. Favorable patient outcome is vital to correctly identify intravascular volume depletion and avoid systemic venous congestion. Most of the conventional means of hemodynamic monitoring in the acute healthcare setting are geared toward addressing the cardiac output and maintaining an optimum mean arterial pressure. While assessing and maintaining cardiac output in an acutely ill patient is very important, a venous congestion cascade is often overlooked, which can negatively affect the intraabdominal end organs. The prospect of using point-of-care ultrasound (POCUS) to determine systemic venous congestion could be a potentially handy tool for clinicians. Venous excess ultrasound score (VExUS) has also been utilized by clinicians as a semi-quantitative assessment tool to assess fluid status. This review aims to discuss the potential role of POCUS and VExUS scores in determining systemic venous congestion through a narrative review of recently published literature.

Point-of-Care Ultrasonography in Internal Medicine: Limitations and Pitfalls for Novice Users

Point-of-care ultrasound (POCUS) is increasingly being adopted in the field of internal medicine, leading to the development of POCUS curricula in undergraduate and postgraduate medical education programs. Prominent internal medicine societies and organizations worldwide recognize the expanding utilization of POCUS by internal medicine physicians, emphasizing the need for practitioners to be aware of both its benefits and limitations. Despite the growing enthusiasm for POCUS, clinicians, particularly those with limited clinical experience, must be cautious regarding its inherent limitations and the potential impact on their clinical practice. This review aims to outline the limitations and potential drawbacks of POCUS for medical students, residents, and internists who wish to stay abreast of the escalating use of POCUS in internal medicine and have a desire, or have already commenced, to incorporate POCUS into their practice. Additionally, it provides recommendations for enhancing POCUS proficiency to mitigate these limitations.

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.

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.

Feasibility and Efficacy of Sustained Low-Efficiency Dialysis in Critically Ill Children with Severe Acute Kidney Injury

OBJECTIVES

To examine the feasibility, efficacy, and safety of sustained low-efficiency dialysis (SLED) in hemodynamically unstable, critically ill children.

METHODS

Critically ill patients, 1-18 y old with hemodynamic instability (≥ 1 vasoactive drugs) and severe acute kidney injury (AKI) requiring kidney replacement therapy (KRT) in a tertiary care pediatric intensive care unit were prospectively enrolled. Patients weighing ≤ 8 kg or with mean arterial pressure < 5^th percentile despite > 3 vasoactive drugs, were excluded. Patients underwent SLED until hemodynamically stable and off vasoactive drugs, or lack of need for dialysis. The primary outcome was the proportion of patients in whom the first session of SLED was initiated within 12 h of its indication and completed without premature (< 6 h) termination. Efficacy was estimated by ultrafiltration, urea reduction ratio (URR), and equilibrated Kt/V. Other outcomes included: changes in hemodynamic scores, circuit clotting, adverse events, and changes in indices on point-of-care ultrasonography and echocardiography.

RESULTS

Between November 2018 and March 2020, 18 patients with median age 8.6 y and vasopressor dependency index of 83.2, underwent 41 sessions of SLED. In 16 patients, SLED was feasible within 12 h of indication. No session was terminated prematurely. Ultrafiltration achieved was 4.0 ± 2.2 mL/kg/h, while URR was 57.7 ± 16.2% and eKt/V 1.17 ± 0.56. Hemodynamic scores did not change significantly. Asymptomatic hypokalemia was the chief adverse effect. Sessions were associated with a significant improvement in indices on ultrasound and left ventricular function. Fourteen patients died.

CONCLUSIONS

SLED is feasible, safe, and effective in enabling KRT in hemodynamically unstable children with severe AKI.

Fluid responsiveness assessment using inferior vena cava collapsibility among spontaneously breathing patients: Systematic review and meta-analysis

OBJECTIVE

To synthesize the evidence about diagnostic accuracy of inferior vena cava collapsibility (IVCc) in prediction of fluid responsiveness among spontaneously breathing patients.

DESIGN

Systematic review of diagnostic accuracy studies.

SETTING

Intensive care units or emergency departments.

PATIENTS AND PARTICIPANTS

spontaneously breathing patients with indication for fluid bolus administration.

INTERVENTIONS

A search was conducted in MEDLINE and EMBASE. We included studies assessing IVCc accuracy for fluid responsiveness assessment with a standard method for cardiac output measure as index test.

MAIN VARIABLES OF INTEREST

General information (year, setting, cutoffs, standard method), sensitivity, specificity, and area under the receiving operator characteristics curve (AUROC). Risk of bias was assessed with QUADAS 2 tool. We obtained the pooled sensitivity, specificity and summary ROC curve, with estimated confidence intervals from a bivariate model. We also calculated positive and negative likelihood ratios and developed a Fagon nomogram.

RESULTS

Eight studies were included with 497 patients. Overall, the studies presented a high risk of bias. IVCc sensitivity was 63% (95% CI - 46-78%) and specificity 83% (95% CI - 76-87%). Despite moderate accuracy of IVCc (SROC 0.83, 95% CI - 0.80-0.86), post-test probability of being fluid responsive based on a 50% pre-test probability led to considerable misclassification.

CONCLUSIONS

IVCc had moderate accuracy for fluid responsiveness assessment in spontaneously breathing patients and should not be used in isolation for this purpose.

Concise, Practical Review on Transthoracic Lung Ultrasound in Prehospital Diagnosis of Dyspnea in Adults

Ultrasonography is a relatively young but widely recognized method of imaging parenchymal organs, including the lungs. Our concise, practical review on transthoracic lung ultrasound (LUS) in the prehospital diagnosis of dyspnea in adults attempts to summarize current knowledge in the field. Furthermore, we discussed POCUS protocols in the analyzed context, discussing their usefulness. We concluded that bedside ultrasonography, or point of care (POCUS), is developing rapidly; however, the knowledge about the use of LUS in a pre-hospital setting is scarce, highlighting the need for further research in this field. Additionally, despite the possibility of using various ultrasound protocols in diagnosing a patient with dyspnea, there is no comprehensive and, at the same time, highly sensitive and specific protocol covering a satisfactory saccade of differential diagnosis of this symptom. It seems reasonable to conduct further targeted research to create such a dedicated solution.

Evaluation Of Congestion Levels in Septic Patients Admitted to Critical Care Units with a Combined Venous Excess-Lung Ultrasound Score (VExLUS) - a Research Protocol

Sepsis is defined as a life-threatening organ dysfunction caused by a dysregulated host response to infection with a high mortality rate. Septic shock is a subset of sepsis with manifest circulatory dysfunction (use of vasopressors and persistent elevation of lactic acid) . As stated in literature, in addition to the use of empiric antibiotics and control of the infectious focus, intravenous fluid therapy is an essential intervention to promote hemodynamic stabilization. However, the literature also describes harmful outcomes related to fluid overload. Hemodynamic management in critically ill patients has traditionally focused on maintaining adequate cardiac output and arterial blood pressure by relying on fluid administration and/or vasopressor/inotropic support. However, organ perfusion is affected by other important factors, such as venous pressure, which can be overlooked. The evaluation of lung congestion with point of care ultrasound (POCUS), as a signal of extravascular fluid, and, more recently, a venous excess Doppler ultrasound (VExUS) grading system, are parameters for the assessment of the fluid status of the patient and organ congestion. Our main hypothesis is that adding a modified lung ultrasound score to the VExUS protocol could provide higher sensitivity and earlier identification of fluid overload, guiding the clinician in the decision of fluid administration in patients with sepsis.

The diagnostic capabilities of the combined cardiac and lung point of care ultrasound in shocked patients at the emergency department - Resourced limited country

Purpose

Cardiac, lung, and inferior vena cava (IVC) ultrasound are commonly performed in the care of emergency patients especially patient presented with hypotension or shock. However, the literature indicated the limitation of IVC to assess shocked patients. This study aims to determine the efficacy of combined cardiac and lung ultrasound for evaluation the etiology of shock.

Materials and Methods

A cross-sectional study was conducted on patient with shock at emergency department, Srinagarind Hospital, Thailand, from January to December 2021. Adult shocked patients who met the criteria were included in this study. Ultrasound and emergency department medical records were documented and analyzed as sensitivity, specificity, predictive value, negative predictive value, diagnostic accuracy, and Cohen's kappa coefficient (κ).

Results

One hundred and two who met the criteria were enrolled. Combined cardiac and lung scans were found to be accurate 99.02% and 93.04% in obstructive and cardiogenic shock. In patients with obstructive shock was the almost perfect agreement, (κ) = 0.85. However, distributive, and hypovolemic shock had the low concordance with the final hospital diagnosis, (κ) = 0.37 and 0.43, respectively.

Conclusions

The integration of cardiac and lung ultrasound can be effectively used to narrow differential diagnosis of shock.

Accuracy of echocardiography and ultrasound protocol to identify shock etiology in emergency department

Background

Early diagnosis and appropriate management of shock aimed at prevention of prolonged hypoperfusion has shown to decrease morbidity and mortality in patients with undifferentiated shock. However, there is often a challenge in emergency department (ED) – where diagnosis is mainly based on clinical signs and standard monitoring parameters. Early use of point of care ultrasound could reduce the diagnostic time and improve diagnostic accuracy.

Purpose

The aim of this study is to investigate the accuracy of echocardiography - ultrasound protocol to identify the cause of shock in ED.

Method

The study was conducted on 150 shocked patients admitted to emergency department of Alexandria Main University Hospital from December 2018 to December 2020. The study was conducted to reach initial impression about shock etiology which was then compared to final diagnosis to determine accuracy, agreement, sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV).

Results

One hundred forty patients were included in the study (10 patients were excluded). The protocol was 100% accurate for diagnosing cases with obstructive and mixed obstructive distributive shock. It showed excellent rule- out characteristics for cardiogenic shock (sensitivity and NPV = 100%). There was almost perfect agreement between provisional and final shock type for mixed distributive cardiogenic shock (kappa 0.915). Echo- US protocol had lowest agreement and PPV for patients with hypovolemic shock Kappa 0.48 and 35% respectively.

Conclusion

The Echo- US protocol showed a high accuracy in identifying shock etiology in ED and is likely a promising diagnostic tool in emergency care.

The Intensivist's Perspective of Shock, Volume Management, and Hemodynamic Monitoring

One of the primary reasons for intensive care admission is shock. Identifying the underlying cause of shock (hypovolemic, distributive, cardiogenic, and obstructive) may lead to entirely different clinical pathways for management. Among patients with hypovolemic and distributive shock, fluid therapy is one of the leading management strategies. Although an appropriate amount of fluid administration might save a patient's life, inadequate (or excessive) fluid use could lead to more complications, including organ failure and mortality due to either hypovolemia or volume overload. Currently, intensivists have access to a wide variety of information sources and tools to monitor the underlying hemodynamic status, including medical history, physical examination, and specific hemodynamic monitoring devices. Although appropriate and timely assessment and interpretation of this information can promote adequate fluid resuscitation, misinterpretation of these data can also lead to additional mortality and morbidity. This article provides a narrative review of the most commonly used hemodynamic monitoring approaches to assessing fluid responsiveness and fluid tolerance. In addition, we describe the benefits and disadvantages of these tools.

Echocardiography in a critical care unit: A contemporary review

INTRODUCTION

Echocardiography is a rapid, noninvasive, and complete cardiac assessment tool for patients with hemodynamic instability. This review provides an overview of the evidence for current practices in critical care units (CCUs), incorporating the use of echocardiography in different etiologies of shock.

AREAS COVERED

: Relevant articles were extracted after searching on databases by two reviewers and incorporated in this review in a narrative style.

EXPERT OPINION

: In an acute scenario, a basic echocardiographic study yields prompt diagnosis, allowing for the initiation of treatment. The most common pathologies in shocked patients are identified promptly using two-dimensional (2D) and M-mode echocardiography. A more comprehensive assessment can follow after patients have been stabilized. There are four types of shock: (i) cardiogenic shock, (ii) hypovolemic shock, (iii) obstructive shock, and (iv) septic shock. All of them can be readily identified by echocardiography. As echocardiography is increasingly being used in an intensive care setting, its applications and evidence base should be expanded by randomized controlled trials to demonstrate patient outcomes in critical care.