Does inferior vena cava respiratory variability predict fluid responsiveness in spontaneously breathing patients?

Predictive accuracy of changes in the inferior vena cava diameter for predicting fluid responsiveness in patients with sepsis: A systematic review and meta-analysis

BACKGROUND

Existing guidelines emphasize the importance of initial fluid resuscitation therapy in sepsis management. However, in previous meta-analyses, there have been inconsistencies in differentiating between spontaneously breathing and mechanically ventilated septic patients.

OBJECTIVE

To consolidate the literature on the predictive accuracy of changes in the inferior vena cava diameter (∆IVC) for fluid responsiveness in septic patients.

METHODS

The Embase, Web of Science, Cochrane Library, MEDLINE, PubMed, Wanfang, China National Knowledge Infrastructure (CNKI), Chinese Biomedical (CBM) and VIP (Weipu) databases were comprehensively searched. Statistical analyses were performed with Stata 15.0 software and Meta-DiSc 1.4.

RESULTS

Twenty-one research studies were deemed suitable for inclusion. The sensitivity and specificity of ∆ IVC were 0.84 (95% CI 0.76, 0.90) and 0.87 (95% CI 0.80, 0.91), respectively. With respect to the distensibility of the inferior vena cava (dIVC), the sensitivity was 0.79 (95% CI 0.68, 0.86), and the specificity was 0.82 (95% CI 0.73, 0.89). For collapsibility of the inferior vena cava (cIVC), the sensitivity and specificity values were 0.92 (95% CI 0.83, 0.96) and 0.93 (95% CI 0.86, 0.97), respectively.

CONCLUSION

The results indicated that ∆IVC is as a dependable marker for fluid responsiveness in sepsis patients. dIVC and cIVC also exhibited high levels of accuracy in predicting fluid responsiveness in septic patients.

Carotid corrected flow time and Doppler shock index for prediction of post-induction hypotension in patients undergoing elective abdominal surgery: a prospective observational study

BACKGROUND

Abdominal surgical patients who have deficient blood volume are at an elevated risk of post-induction hypotension (PIH). New strategies have been adopted, i.e., carotid ultrasound, to evaluate volume status. The study aimed to investigate and compare the predictive value of various carotid ultrasound parameters for PIH.

METHODS

Adult patients scheduled for abdominal surgery were enrolled. Carotid ultrasound was performed before induction to evaluate the carotid flow time (FT), carotid artery velocity time integral (VTI), and Doppler shock index (the DSIFTc and DSIVTI). Both Wodey's (W) and Bazett's (B) formulae determined the corrected flow time (FTc). The predictive ability of these parameters was analyzed via receiver operating characteristic (ROC) curve analysis.

RESULTS

Finally, 94 patients were analyzed, and of those, 40 (42.6%) developed PIH. The areas under the curve for FT, FTc(W), 1/DSIFTc, and FTc(B) were 0.790 (95% CI 0.697-0.883) (P < 0.05), 0.788 (95% CI 0.695-0.881) (P < 0.001), 0.729 (95% CI 0.626-0.832) (P < 0.001), and 0.689 (95% CI 0.582-0.796) (P < 0.05), respectively. The optimal cut-off for FTc(W) was 334.15 ms (sensitivity 82.5%, specificity 70.4%), while for FT, it was 313.33 ms (sensitivity 72.5%, specificity 79.6%), indicating FTc(W) as the best predictor among these various parameters. The 1/DSIFTc was an inferior predictor of PIH, with an optimal cutoff value of 4.58. The sensitivity (80.0%) and specificity (61.1%) values were obtained.

CONCLUSION

Carotid flow time corrected by Wodey's formula was a reliable indicator of PIH in patients undergoing elective abdominal surgery, superior to FT, DSIFTc, and FTc(B).

Correlation Between the Inferior Vena Cava/Aorta (Ivc/Ao) Ratio and Serum Lactate Levels in Children With Renal Disorder

Background

Acute kidney injury (AKI) is common in critically ill children in the PICU, with incidence rates from 2.5% to 58%, impacting mortality and hospital duration. Early AKI detection is vital, but conventional hemodynamic monitoring often lacks specificity. This study investigates the relationship between the inferior vena cava/aortic (IVC/Ao) ratio and serum lactate levels as non-invasive indicators of renal hemodynamics and tissue perfusion in children. Understanding these parameters could improve early diagnosis, aid clinical decisions, and enhance outcomes for pediatric AKI patients, offering an accessible monitoring method for clinicians.

Methods

This cross-sectional study involved 48 pediatric patients aged 5-18 years showing Pediatric Early Warning Score (PEWS) ≥3 and diagnosed with renal disorders. Patients were admitted to the emergency department, high care unit, PICU, and pediatric ward at Dr. Hasan Sadikin Hospital, Bandung, between May and August 2023. AKI was diagnosed using pRIFLE or KDIGO criteria. The IVC/Ao ratio was assessed via transabdominal USG, and serum lactate levels were measured. Spearman correlation analysis was conducted to assess their relationship.

Results

The median (IQR) IVC/Ao ratio was 0.91 (0.70-1.10), and serum lactate levels were 1.5 (1.1-2.4) mmol/L. Spearman correlation analysis revealed a negative correlation between the IVC/Ao ratio and serum lactate (rho = -0.65, p < 0.001).

Conclusion

A decrease in the IVC/Ao ratio correlates with an increase in serum lactate levels in children with AKI.

Assessing fluid responsiveness by using functional hemodynamic tests in critically ill patients: a narrative review and a profile-based clinical guide

Fluids are given with the purpose of increasing cardiac output (CO), but approximately only 50% of critically ill patients are fluid responders. Since the effect of a fluid bolus is time-sensitive, it diminuish within few hours, following the initial fluid resuscitation. Several functional hemodynamic tests (FHTs), consisting of maneuvers affecting heart-lung interactions, have been conceived to discriminate fluid responders from non-responders. Three main variables affect the reliability of FHTs in predicting fluid responsiveness: (1) tidal volume; (2) spontaneous breathing activity; (3) cardiac arrythmias. Most FTHs have been validated in sedated or even paralyzed ICU patients, since, historically, controlled mechanical ventilation with high tidal volumes was the preferred mode of ventilatory support. The transition to contemporary methods of invasive mechanical ventilation with spontaneous breathing activity impacts heart-lung interactions by modifying intrathoracic pressure, tidal volumes and transvascular pressure in lung capillaries. These alterations and the heterogeneity in respiratory mechanics (that is present both in healthy and injured lungs) subsequently influence venous return and cardiac output. Cardiac arrythmias are frequently present in critically ill patients, especially atrial fibrillation, and intuitively impact on FHTs. This is due to the random CO fluctuations. Finally, the presence of continuous CO monitoring in ICU patients is not standard and the assessment of fluid responsiveness with surrogate methods is clinically useful, but also challenging. In this review we provide an algorithm for the use of FHTs in different subgroups of ICU patients, according to ventilatory setting, cardiac rhythm and the availability of continuous hemodynamic monitoring.

Navigating the Waves of Critical Care Echocardiography: Unveiling its Role, Advantages, and Pitfalls in the Cardiac Intensive Care Unit

PURPOSE OF REVIEW

Critical Care Echocardiography (CCE) is now established as an important tool in the intensive care unit (ICU). This paper aims to examine the expanding role of cardiovascular ultrasound in the ICU, focusing on its applications, benefits, and challenges, while highlighting recent advancements shaping the future of critical care echocardiography.

RECENT FINDINGS

Non-invasive echocardiographic measurement of hemodynamic parameters including stroke volume, cardiac output, left ventricular filling pressures, and pulmonary pressures have been well-validated against invasive measurements. Myocardial perfusion can also be evaluated using ultrasound enhancing agent techniques to further risk-stratify patients with chest pain. Echocardiography enables clinicians to visualize cardiac anatomy and physiology directly at the bedside, providing immediate feedback in rapidly changing clinical situations. Assessment of stroke volume, cardiac output, and left ventricular filling pressures can be readily measured at the bedside and correspond with clinical outcomes including mortality. Measurement of central venous pressure and pulmonary pressures may guide clinical decisions in fluid management and mechanical ventilation strategies. Lastly, myocardial perfusion imaging can supplement the 2D echocardiographic evaluation to further risk-stratify patients presenting with chest pain.

Assessment of Fluid Responsiveness via Central Venous Ultrasound Measurement: A Network Meta-Analysis

Background: Ultrasonographic assessment of the diameters of various veins and their indices are among the most applied diagnostic tools for evaluating fluid responsiveness in clinical practice. Despite their widespread use, there is no definitive answer on which is preferable. Our study aimed to investigate the diagnostic accuracy of different venous diameters and their indices to assess fluid responsiveness. Methods: We conducted a systematic review and network meta-analysis, analyzing prospective studies evaluating the diagnostic accuracy of venous diameters (inferior vena cava [IVC], internal jugular vein [IJV], superior vena cava, and subclavian vena) and their indices for fluid responsiveness. Electronic databases were searched from inception until March 2024; this search was supplemented by snowballing methods. The risk of bias was evaluated with QUADAS-2, and evidence certainty was assessed using the GRADE approach. Nine prospective cohort studies (560 patients) were included. Results: The network meta-analysis revealed that the ΔCaval index exhibited a significant performance advantage over other "venous" test parameters. The caval index significantly outperformed IJV min/max and IVCmax. IJV index and IVCmin significantly outperformed IJVmin/max. The caval index was comparable to the IJV index. The caval index was comparable during mechanical ventilation and spontaneous breathing. Conclusions: In this meta-analysis, the ΔCaval index test showed higher diagnostic accuracy for fluid responsiveness compared with other venous tests. Caval and jugular indices displayed similar accuracy, and caval indices were consistent under mechanical ventilation and spontaneous breathing. Indices generally outperformed absolute values, except for IVCmin, which equaled the caval index in efficacy. This study was registered on the International Platform for Registered Protocols for Systematic Reviews and Meta-Analyses: INPLASY202430104.

2025 Expert Consensus Recommendations for the Diagnostic Requirements in Routine Practices of Transthoracic Echocardiography

Transthoracic echocardiography plays a crucial role in clinical diagnosis and is increasingly being used around the world. Comprehensive echocardiographic examinations require accurate measurements and the operators to have excellent technical skills. Despite the availability of several published echocardiographic guidelines, the absence of recommended operational manuals in daily practice has resulted in significant variation in the content of echocardiography reports across different medical institutions. This variability has created communication barriers between medical institutions and also hampered the development of a national echocardiography database in Taiwan. Balancing quality and efficiency is a critical concern in echocardiography, and most published guidelines for echocardiography primarily focus on disease categorization. In the current document, we focus on information about the scanning sequence, including scanning techniques, common pitfalls, simple disease interpretation, and the recommended intensity. Based on a growing body of research, we particularly emphasize right-sided imaging and measurement information. We also discuss equipment settings, which have often been overlooked but are essential to obtaining good imaging and accurate measurements. Our recommendations could enhance clinicians' and sonographers' understanding of the core aspects of echocardiography and were developed with consideration of the health-care payment system in Taiwan. Implementing our recommendations may subsequently enable the establishment of a national echocardiography database in Taiwan.

[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.

Advances in the application of ultrasonographic parameters for fluid management in obstetric anesthesia

Ultrasound provides a valuable non-invasive approach for fluid management in obstetric anesthesia. Ultrasonographic parameters assist anesthesiologists to effectively assess the fluid status of parturients and reduce related complications. In addition to conventional parameters, which have been widely validated in clinical practice, we provide new insights into arterial parameters such as peak velocity, velocity-time integral, corrected flow time, and vein-related parameters, including the internal jugular vein and its collapsibility index, the inferior vena cava and its collapsibility index, as well as subclavian vein and its collapsibility index. These parameters can potentially enhance fluid management in obstetric anesthesia.

Evaluation of the role of repeated inferior vena cava sonography in estimating first 24 h fluid requirement in resuscitation of major blunt trauma patients in emergency department Suez Canal University Hospital

INTRODUCTION

The assessment of hemodynamic status in polytrauma patients is an important principle of the primary survey of trauma patients, and screening for ongoing hemorrhage and assessing the efficacy of resuscitation is vital in avoiding preventable death and significant morbidity in these patients. Invasive procedures may lead to various complications and the IVC ultrasound measurements are increasingly recognized as a potential noninvasive replacement or a source of adjunct information.

AIMOF THIS STUDY

The study aimed to determine if repeated ultrasound assessment of the inferior vena cava (diameter, collapsibility (IVC- CI) in major trauma patients presenting with collapsible IVC before resuscitation and after the first hour of resuscitation will predict total intravenous fluid requirements at first 24 h.

PATIENTS & METHODS

The current study was conducted on 120 patients presented to the emergency department with Major blunt trauma (having significant injury to two or more ISS body regions or an ISS greater than 15). The patients(cases) group (shocked group) (60) patients with signs of shock such as decreased blood pressure < 90/60 mmHg or a more than 30% decrease from the baseline systolic pressure, heart rate > 100 b/m, cold, clammy skin, capillary refill > 2 s and their shock index above0.9. The control group (non-shocked group) (60) patients with normal blood pressure and heart rate, no other signs of shock (normal capillary refill, warm skin), and (shock index ≤ 0.9). Patients were evaluated at time 0 (baseline), 1 h after resucitation, and 24 h after 1st hour for:(blood pressure, pulse, RR, SO2, capillary refill time, MABP, IVCci, IVCmax, IVCmin).

RESULTS

Among 120 Major blunt trauma patients, 98 males (81.7%) and 22 females (18.3%) were included in this analysis; hypovolemic shocked patients (60 patients) were divided into two main groups according to IVC diameter after the first hour of resuscitation; IVC repleted were 32 patients (53.3%) while 28 patients (46.7%) were IVC non-repleted. In our study population, there were statistically significant differences between repleted and non-repleted IVC cases regarding IVCD, DIVC min, IVCCI (on arrival) (after 1 h) (after 24 h of 1st hour of resuscitation) ( p-value < 0.05) and DIVC Max (on arrival) (after 1 h) (p-value < 0.001). There is no statistically significant difference (p-value = 0.075) between repleted and non-repleted cases regarding DIVC Max (after 24 h).In our study, we found that IVCci0 at a cut-off point > 38.5 has a sensitivity of 80.0% and Specificity of 85.71% with AUC 0.971 and a good 95% CI (0.938 - 1.0), which means that IVCci of 38.6% or more can indicate fluid responsiveness. We also found that IVCci 1 h (after fluid resuscitation) at cut-off point > 28.6 has a sensitivity of 80.0% and Specificity of 75% with AUC 0.886 and good 95% CI (0.803 - 0.968), which means that IVCci of 28.5% or less can indicate fluid unresponsiveness after 1st hour of resuscitation. We found no statistically significant difference between repleted and non-repleted cases regarding fluid requirement and amount of blood transfusion at 1st hour of resuscitation (p-value = 0.104).

CONCLUSION

Repeated bedside ultrasonography of IVCD, and IVCci before and after the first hour of resuscitation could be an excellent reliable invasive tool that can be used in estimating the First 24 h of fluid requirement in Major blunt trauma patients and assessment of fluid status.

Correlation between inferior vena cava collability index and malnutrition in critical patients: A prospective observational study

Background

We aimed to investigate the correlation between the inferior vena cava collability index(IVC-CI) used in the evaluation of fluid volume and the Nutrition Risk Index(NRI), Prognostic Nutrition Index(PNI), Geriatric Nutrition Risk Index(GNRI) and Controlling Nutritional Status Scoring(CONUT) used in the evaluation of malnutrition.

Methods

This study is a prospective observational study. Demographic data, laboratory data, Body Max Indexes(BMI), NRI, PNI, GNRI and CONUT in the first 24 hours of admission to the intensive care unit of 96 critically ill patients admitted to the tertiary intensive care unit with assisted invasive mechanical ventilator support and IVC-CI values were recorded. Patients with an IVC-CI >45% were evaluated as hypovolemia. Of the patients, 61 (63.5%) patients with an IVC-CI value of 45%≥ were group 1, and 35 (36.5%) patients with an IVC-CI value of >45% were determined as group 2. Correlation between the IVC-CI and malnutrition scores was investigated between the groups.

Results

As a result of the statistical analysis; there was a statistically significant difference between the two groups in terms of BMI, NRI, PNI, GNRI and CONUT (p<0.001). According to the correlation analysis results, NRI (rs=-0.716, p<0.001), PNI (rs=-0.743, p<0.001), GNRI (rs=-0.723, p<0.001), CONUT (rs=0.741, p<0.001) were significantly correlated with the IVC-CI.

Conclusions

This study shows that there is a correlation between the IVC-CI used in the evaluation of fluid volume and malnutrition.

How to use echocardiography to manage patients with shock?

Echocardiography enables the intensivist to assess the patient with circulatory failure. It allows the clinician to identify rapidly the type and the cause of shock in order to develop an effective management strategy. Important characteristics in the setting of shock are that it is non-invasive and can be rapidly applied. Early and repeated echocardiography is a valuable tool for the management of shock in the intensive care unit. Competency in basic critical care echocardiography is now regarded as a mandatory part of critical care training with clear guidelines available. The majority of pathologies found in shocked patients are readily identified using basic level 2D and M-mode echocardiography. The four core types of shock (cardiogenic, hypovolemic, obstructive, and septic) can readily be identified by echocardiography. Echocardiography can differentiate the different pathologies that may be the cause of each type of shock. More importantly, as a result of more complex and elderly patients, the shock may be multifactorial, such as a combination of cardiogenic and septic shock, which emphasises on the added value of transthoracic echocardiography (TTE) in such population of patients. In this review we aimed to provide to clinicians a bedside strategy of the use of TTE parameters to manage patients with shock. In the first part of this overview, we detailed the different TTE parameters and how to use them to identify the type of shock. And in the second part, we focused on the use of these parameters to evaluate the effect of treatments, in different types of shock.

Usefulness of Non-Invasive Parameters (Inferior Vena Cava Diameter, Inferior Vena Cava Collapsibility, Inferior Vena Cava-Aortic Ratio) for Hemodynamic Monitoring in Critically Ill Children: A Systematic Review

Purpose

Volume measurement in critically ill children can be conducted using invasive procedure such as Central Venous Pressure (CVP), or non-invasive procedure such as measurement of Inferior Vena Cava (IVC) indices using ultrasonography. However, their accuracy and efficacy are still under scrutiny. We aim to compare CVP and IVC indices as non-invasive parameters in assessing volume status in critically ill children.

Methods

We conducted a systematic review based on literature searching from four electronic databases which were PubMed, Cochrane, ScienceDirect, SpringerLink with keywords: "CENTRAL VENOUS PRESSURE", "INFERIOR VENA CAVA DIAMETER", "INFERIOR VENA CAVA COLLAPSIBILITY", "INFERIOR VENA CAVA AORTIC-RATIO", "VOLUME STATUS", "FLUID STATUS", "CRITICAL ILL", "CHILDREN", and "PEDIATRICS". We included relevant studies in English published from 2000 to 2023 on critically ill children aged 0-18 years. Comparison between CVP and IVC indices was resumed.

Results

Eight articles were included in this study. Majority of the studies showed a consistent correlation between CVP and IVC indices. IVC-CI was the most common parameter evaluated in the included studies. There was moderate to strong correlations using IVC-CI and IVC-DI, and moderate correlation using IVC-Ao ratio.

Conclusion

We found that non-invasive tools might have a potential role to measure volume in critically ill children equals to CVP. Further high-quality and longitudinal studies are needed to validate these findings and to establish a clear guideline for the non-invasive tool to be used in daily clinical practice.

Use of POCUS for the assessment of dehydration in pediatric patients-a narrative review

In pediatric practice, POCUS (point-of-care ultrasound) has been mostly implemented to recognize lung conditions and pleural and pericardial effusions, but less to evaluate fluid depletion. The main aim of this review is to analyze the current literature on the assessment of dehydration in pediatric patients by using POCUS. The size of the inferior vena cava (IVC) and its change in diameter in response to respiration have been investigated as a tool to screen for hypovolemia. A dilated IVC with decreased collapsibility (< 50%) is a sign of increased right atrial pressure. On the contrary, a collapsed IVC may be indicative of hypovolemia. The IVC collapsibility index (cIVC) reflects the decrease in the diameter upon inspiration. Altogether the IVC diameter and collapsibility index can be easily determined, but their role in children has not been fully demonstrated, and an estimation of volume status solely by assessing the IVC should thus be interpreted with caution. The inferior vena cava/abdominal aorta (IVC/AO) ratio may be a suitable parameter to assess the volume status in pediatric patients even though there is a need to define age-based thresholds. A combination of vascular, lung, and cardiac POCUS could be a valuable supplementary tool in the assessment of dehydration in several clinical scenarios, enabling rapid identification of life-threatening primary etiologies and helping physicians avoid inappropriate therapeutic interventions.   Conclusion: POCUS can provide important information in the assessment of intravascular fluid status in emergency scenarios, but measurements may be confounded by a number of other clinical variables. The inclusion of lung and cardiac views may assist in better understanding the patient's physiology and etiology regarding volume status. What is Known: • In pediatric practice, POCUS (point-of-care ultrasound) has been mostly implemented to recognize lung conditions (like pneumonia and bronchiolitis) and pleural and pericardial effusions, but less to evaluate fluid depletion. • The size of the IVC (inferior vena cava) and its change in diameter in response to respiration have been studied as a possible screening tool to assess the volume status, predict fluid responsiveness, and assess potential intolerance to fluid loading. What is New: • The IVC diameter and collapsibility index can be easily assessed, but their role in predicting dehydration in pediatric age has not been fully demonstrated, and an estimation of volume status only by assessing the IVC should be interpreted carefully. • The IVC /AO(inferior vena cava/abdominal aorta) ratio may be a suitable parameter to assess the volume status in pediatric patients even though there is a need to define age-based thresholds. A combination of vascular, lung, and cardiac POCUS can be a valuable supplementary tool in the assessment of intravascular volume in several clinical scenarios.

Diagnostic accuracy of left ventricular outflow tract velocity time integral versus inferior vena cava collapsibility index in predicting post-induction hypotension during general anesthesia: an observational study

BACKGROUND

Point of care ultrasound (POCUS) is being explored for dynamic measurements like inferior vena cava collapsibility index (IVC-CI) and left ventricular outflow tract velocity time integral (LVOT-VTI) to guide anesthesiologists in predicting fluid responsiveness in the preoperative period and in treating post-induction hypotension (PIH) with varying accuracy.

METHODS

In this prospective, observational study on included 100 adult patients undergoing elective surgery under general anesthesia, the LVOT-VTI and IVC-CI measurements were performed in the preoperative room 15 minutes prior to surgery, and PIH was measured for 20 minutes in the post-induction period.

RESULTS

The incidence of PIH was 24%. The area under the curve, sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy of the two techniques at 95% confidence interval was 0.613, 30.4%, 93.3%, 58.3%, 81.4%, 73.6% for IVC-CI and 0.853, 83.3%, 80.3%, 57.1%, 93.8%, 77.4% for LVOT-VTI, respectively. In multivariate analysis, the cutoff value for IVC-CI was >51.5 and for LVOT-VTI it was ≤17.45 for predicting PIH with odd ratio [OR] of 8.491 (P=0.025) for IVCCI and OR of 17.427 (P<0.001) for LVOT. LVOT-VTI assessment was possible in all the patients, while 10% of patients were having poor window for IVC measurements.

CONCLUSIONS

We recommend the use of POCUS using LVOT-VTI or IVC-CI to predict PIH, to decrease the morbidity of patients undergoing surgery. Out of these, we recommend LVOT-VTI measurements as it has showed a better diagnostic accuracy (77.4%) with no failure rate.

Effect of carotid corrected flow time combined with perioperative fluid therapy on preventing hypotension after general anesthesia induction in elderly patients: a prospective cohort study

BACKGROUND

Hypotension often occurs following the induction of general anesthesia in elderly patients undergoing surgery and can lead to severe complications. This study assessed the effect of carotid corrected flow time (FTc) combined with perioperative fluid therapy on preventing hypotension after general anesthesia induction in elderly patients.

MATERIALS AND METHODS

The prospective cohort study was divided into two parts. The first part (Part I) consisted of 112 elderly patients. Carotid FTc was measured using Color Doppler Ultrasound 5 min before anesthesia induction. Hypotension was defined as a decrease of greater than 30% in systolic blood pressure (SBP) or a decrease of greater than 20% in mean arterial pressure (MAP) from baseline, or an absolute SBP below 90 mmHg and MAP below 60 mmHg within 3 min after induction of general anesthesia. The predictive value of carotid FTc was determined using receiver operating characteristic (ROC) curve. The second part (Part II) consisted of 65 elderly patients. Based on the results in Part I, elderly patients with carotid FTc below the optimal cut-off value received perioperative fluid therapy at a volume of 8 ml/kg of balanced crystalloids (lactated Ringer's solution) in 30 min before induction. The effect of carotid FTc combined with perioperative fluid therapy was assessed by comparing observed incidence of hypotension after induction.

RESULTS

The area under the ROC for carotid FTc to predict hypotension after induction was 0.876 [95% confidence interval (CI) 0.800-0.952, P <0.001]. The optimal cut-off value was 334.95 ms (sensitivity of 87.20%; specificity of 82.20%). The logistic regression analysis revealed that carotid FTc is an independent predictor for post-induction hypotension in elderly patients. The incidence of post-induction hypotension was significantly lower ( P <0.001) in patients with carotid FTc less than 334.95 ms who received perioperative fluid therapy (35.71%) compared to those who did not (92.31%).

CONCLUSIONS

Carotid FTc combined with the perioperative fluid therapy could significantly reduce the incidence of hypotension after the induction of general anesthesia in elderly patients.

The diagnostic accuracy of preoperative perfusion index as a predictor of postspinal anesthesia hypotension in parturients undergoing cesarean delivery: A prospective non-blinded observational study

BACKGROUND AND OBJECTIVES

Spinal anesthesia is the technique of choice for elective cesarean section with a prominent side effect of postspinal anesthesia hypotension (PSH). This needs an early prediction to avoid feto-maternal complication. This study aimed to assess the diagnostic accuracy of perfusion index (PI) and inferior vena cava collapsibility index (IVCCI) in the prediction of PSH.

MATERIAL AND METHODS

Thirty parturients of American Society of Anesthesiologists Physical Status (ASA-PS) 1 and two undergoing cesarean delivery participated in the study. IVCCI, PI, baseline systolic blood pressure (SBP), diastolic blood pressure (DBP), mean blood pressure (MBP), and heart rate (HR) were noted in the preoperative period. The fall of MBP by 20% from baseline or below 65 mm Hg was considered PSH. After spinal anesthesia, SBP, DBP, MBP, and HR were noted again for diagnosing PSH.

RESULTS

It did not show any statistical difference when comparing the PI between the PSH and non-PSH groups in both the PSH definition groups. IVCCI was significantly higher when PSH was considered MBP <65 mm Hg (P = 0.01). However, IVCCI was found to be statistically insignificant if PSH was considered a 20% reduction in baseline MBP. The correlation matrix between IVCCI and PI showed Pearson's r-value of 0.525, indicating a substantial relationship between the two (P = 0.003). Multivariate logistic regression analysis had shown that neither IVCCI nor PI was a good predictor of PSH in parturients for both definition groups for PSH.

CONCLUSION

Although there is a modest correlation between PI and IVCCI, both cannot be used to predict postspinal hypotension in parturients undergoing elective lower-segment cesarean section (LSCS).

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.

Inferior vena cava to aorta ratio in dehydrated pediatric patients: a systematic review and meta-analysis

BACKGROUND

Dehydration due to acute diarrhea is among the leading causes of mortality. However, advancements in management and technology do not help clinicians differentiate dehydration degrees. Ultrasound using the inferior vena cava to aorta (IVC/ Ao) ratio is a promising noninvasive technique to identify significant pediatric dehydration.

PUSPOSE

Therefore, this systematic review and meta-analysis aimed to examine the diagnostic parameters of the IVC/Ao ratio for predicting clinically significant dehydration in pediatric patients.

METHODS

We searched the MEDLINE, PubMed, Cochrane Library, ScienceDirect, and Google Scholar databases for studies of pediatric patients (≤18 years old) who presented with signs and symptoms of dehydration due to acute diarrhea, gastroenteritis, or vomiting. The inclusion criteria were cross-sectional, case-control, cohort, and randomized controlled trial study design and publication in any language. We then conducted a meta-analysis using the midas and metandi commands from Stata software.

RESULTS

Five studies of 461 patients were included. The combined sensitivity was 86% (95% confidence interval [CI], 79%-91%), while the specificity was 73% (95% CI, 59%-84%). The area under the curve was 0.89 (95% CI, 0.86-0.91). The positive likelihood ratio (LR+) was 3.2 (95% CI, 2.1-5.1) with a 76% posttest probability, while the negative likelihood ratio (LR-) was 0.18 (95% CI, 0.12-0.28) with a 16% posttest probability. The combined negative predictive value was 0.83 (95% CI, 0.75-0.91), while the positive predictive value was 0.75 (95% CI, 0.68-0.82).

CONCLUSION

The IVC/Ao ratio was insufficient to exclude or confirm significant dehydration in pediatric patients. More studies are needed, especially multicenter, adequately powered diagnostic research, to will help establish the usefulness of the IVC/Ao ratio.

Association of infraclavicular axillary vein diameter and collapsibility index with general anesthesia-induced hypotension in elderly patients undergoing gastrointestinal surgery: an observational study

BACKGROUND

The collapse index of inferior Vena Cava (IVC) and its diameter are important predictive tools for fluid responsiveness in patients, especially critically ones. The collapsibility of infraclavicular axillary vein (AXV) can be used as an alternative to the collapsibility of IVC (IVC-CI) to assess the patient's blood volume.

METHODS

A total of 188 elderly patients aged between 65 and 85 years were recruited for gastrointestinal surgery under general anesthesia. Ultrasound measurements AXV and IVC were performed before induction of general anesthesia. Patients were grouped in accordance to the hypotension after induction. ROC curves were used to analyze the predictive value of ultrasound measurements of AXV and IVC for hypotension after induction of anesthesia. Pearson linear correlation was used to assess the correlation of ultrasound measurements and decrease in mean arterial blood pressure (MAP).

RESULTS

The maximum diameter of AXV(dAXVmax) and the maximum diameter of IVC (dIVCmax) were not related to the percentage decrease in MAP; the collapsibility of AXV (AXV-CI) and IVC-CI were positively correlated with MAP changes (correlation coefficients:0.475, 0.577, respectively, p < 0.001). The areas under the curve (AUC) was 0.824 (0.759-0.889) for AXV-CI, and 0.874 (0.820-0.928) for IVC-CI. The optimal threshold for AXV-CI was 31.25% (sensitivity 71.7%, specificity 90.1%), while for IVC-CI was 36.60% (sensitivity 85.9%, specificity 79.0%). Hypotension and down-regulation of MAP during induction can be accurately predicted by AXV-Cl after correction for confounding variables.

CONCLUSION

Infraclavicular axillary vein diameter has no significant correlation with postanesthesia hypotension, whereas AXV-CI may predict postanesthesia hypotension during gastrointestinal surgery of the elderly.

TRIAL REGISTRATION

This study was registered in the Clinical Trial Registry of China on 05/06/2022 (ChiCTR2200060596).

THE ACCURACY OF INFERIOR VENA CAVA DISTENSIBILITY THROUGH THE TRANSHEPATIC APPROACH TO PREDICT FLUID RESPONSIVENESS IN PATIENTS WITH SEPTIC SHOCK AFTER EMERGENCY LAPAROTOMY

ABSTRACT

Background: We aimed to evaluate the ability of inferior vena cava (IVC) distensibility using the transhepatic approach to predict fluid responsiveness in mechanically ventilated patients with septic shock after emergency laparotomy. Methods: This prospective observational study included mechanically ventilated paralyzed adult who had septic shock after emergency laparotomy. The IVC dimensions were measured through the transhepatic and subxiphoid approaches. The fluid responsiveness was confirmed with >15% increase in cardiac output after 500 mL of fluid bolus. The outcomes were the ability of transhepatic (primary outcome) and subxiphoid approach to predict fluid responders using the area under the receiver operating characteristics curve analysis. The gray zone for the two approaches was calculated. Results: Data from 51 patients were analyzed, and the number of fluid responders was 30 of 52 (58%). The transhepatic approach was feasible in all patients, whereas the subxiphoid approach was only feasible in 42 patients. The area under the receiver operating characteristics curve (95% confidence interval) for the transhepatic IVC distensibility was 0.88 (0.76-0.95), and it was comparable with that of the subxiphoid approach (0.81 [0.66-0.92], P = 0.417). The gray zone for the transhepatic IVC distensibility was 17% to 35% including 24 of 51 patients (47%), whereas the gray zone for the subxiphoid IVC distensibility was 13% to 34% including 18 of 42 patients (43%). Conclusion: In conclusion, the transhepatic approach for evaluation of IVC distensibility showed good accuracy in predicting fluid responsiveness in patients with septic shock after emergency laparotomy. The transhepatic approach showed the same accuracy as the subxiphoid approach with the advantage of being feasible in larger number of patients.

Does respiratory variation in inferior vena cava diameter predict fluid responsiveness in adult patients? A systematic review and meta-analysis of diagnostic accuracy studies

Objectives:

To systematically review the diagnostic utility of the respiratory variation of the inferior vena cava diameter measured using ultrasonography for predicting fluid responsiveness in adult patients and compare the three commonly used equations, inferior vena cava distensibility, inferior vena cava collapsibility and inferior vena cava variability.

Methods:

We searched PubMed, Scopus, Web of Science and Cochrane library, and included studies investigating the diagnostic accuracy of the respiratory variation of the inferior vena cava measured using ultrasonography compared to a reference standard for measuring cardiac output after a fluid challenge for fluid responsiveness, and stratified participants as fluid responsive or not. We included studies conducted in the emergency department or intensive care unit. We excluded studies on paediatric, prehospital, cancer, pregnant, dialysis patients or healthy volunteers.

Results:

We retrieved 270 records and excluded 171 because of irrelevance, patient population or publication type. We screened the abstracts of 99 studies and then the full texts of 42 studies. Overall, 21 studies with 1321 patients were included, of whom 689 (52%) were fluid responsive. The mean threshold value for positive inferior vena cava distensibility, inferior vena cava collapsibility and inferior vena cava variability was 17%, 35% and 12%, respectively. The heterogeneity between studies was high. Bivariate diagnostic random-effects meta-analysis was used to calculate the summary receiver operating characteristics curves. The overall accuracy, sensitivity and specificity of respiratory variation of the inferior vena cava diameter were 0.85, 0.72 and 0.81, respectively. The accuracy of inferior vena cava distensibility and inferior vena cava collapsibility was similar. The diagnostic utility of respiratory variation of the inferior vena cava diameter was lower but not statistically significant in mechanically ventilated patients compared with spontaneous breathing for predicting fluid responsiveness.

Conclusion:

The respiratory variation of the inferior vena cava diameter has moderate diagnostic utility for predicting fluid responsiveness independent of the equation used.

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.

Inspiratory effort impacts the accuracy of pulse pressure variations for fluid responsiveness prediction in mechanically ventilated patients with spontaneous breathing activity: a prospective cohort study

BACKGROUND

Pulse pressure variation (PPV) is unreliable in predicting fluid responsiveness (FR) in patients receiving mechanical ventilation with spontaneous breathing activity. Whether PPV can be valuable for predicting FR in patients with low inspiratory effort is unknown. We aimed to investigate whether PPV can be valuable in patients with low inspiratory effort.

METHODS

This prospective study was conducted in an intensive care unit at a university hospital and included acute circulatory failure patients receiving volume-controlled ventilation with spontaneous breathing activity. Hemodynamic measurements were collected before and after a fluid challenge. The degree of inspiratory effort was assessed using airway occlusion pressure (P0.1) and airway pressure swing during a whole breath occlusion (ΔPocc) before fluid challenge. Patients were classified as fluid responders if their cardiac output increased by ≥ 10%. Areas under receiver operating characteristic (AUROC) curves and gray zone approach were used to assess the predictive performance of PPV.

RESULTS

Among the 189 included patients, 53 (28.0%) were defined as responders. A PPV > 9.5% enabled to predict FR with an AUROC of 0.79 (0.67-0.83) in the whole population. The predictive performance of PPV differed significantly in groups stratified by the median value of P0.1 (P0.1 < 1.5 cmH2O and P0.1 ≥ 1.5 cmH2O), but not in groups stratified by the median value of ΔPocc (ΔPocc < - 9.8 cmH2O and ΔPocc ≥ - 9.8 cmH2O). Specifically, in patients with P0.1 < 1.5 cmH2O, PPV was associated with an AUROC of 0.90 (0.82-0.99) compared with 0.68 (0.57-0.79) otherwise (p = 0.0016). The cut-off values of PPV were 10.5% and 9.5%, respectively. Besides, patients with P0.1 < 1.5 cmH2O had a narrow gray zone (10.5-11.5%) compared to patients with P0.1 ≥ 1.5 cmH2O (8.5-16.5%).

CONCLUSIONS

PPV is reliable in predicting FR in patients who received controlled ventilation with low spontaneous effort, defined as P0.1 < 1.5 cmH2O. Trial registration NCT04802668. Registered 6 February 2021, https://clinicaltrials.gov/ct2/show/record/NCT04802668.

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.

Monitoring Macro- and Microcirculation in the Critically Ill: A Narrative Review

Circulatory shock is a common and important diagnosis in the critical care environment. Hemodynamic monitoring is quintessential in the management of shock. The currently used hemodynamic monitoring devices not only measure cardiac output but also provide data related to the prediction of fluid responsiveness, extravascular lung water, and also pulmonary vascular permeability. Additionally, these devices are minimally invasive and associated with fewer complications. The area of hemodynamic monitoring is progressively evolving with a trend toward the use of minimally invasive devices in this area. The critical care physician should be well-versed with current hemodynamic monitoring limitations and stay updated with the upcoming advances in this field so that optimal therapy can be delivered to patients in circulatory shock.

Carotid artery corrected flow time and respiratory variation of blood flow peak velocity for prediction of hypotension after induction of general anesthesia in adult patients undergoing emergency laparotomy for peritonitis: A prospective, observational study

Background and Aims

Doppler waveform analysis of carotid artery has been found to predict fluid responsiveness in patients undergoing elective surgeries. We evaluated the role of carotid artery corrected flow time (FTc) and respiratory variation of blood flow peak velocity (ðVpeak) in predicting post induction hypotension in patients undergoing emergency laparotomy for peritonitis.

Material and Methods

Adult patients (n = 60) with perforation peritonitis undergoing emergency laparotomy under general anesthesia (GA) were recruited in this prospective, observational study. Carotid ultrasonography was performed pre-induction, to determine FTc and ðVpeak. Post-induction hemodynamic parameters were recorded for 5 minutes. Spearman's rank correlation coefficient was used to determine the relationship between hypotension and carotid artery measurements.

Results

Post-induction hypotension occurred in 48.3% of patients. The carotid artery FTc was significantly lower (P = 0.008) in patients who developed post-induction hypotension, but ðVpeak was statistically similar (P = 0.62) in both groups. Spearman's rank correlation coefficient revealed a statistically significant correlation between FTc and systolic blood pressure (SBP) change at one-minute post induction (r2 = -0.29, P = 0.03); however statistical significance were not achieved at 2 minutes and 3 minutes (P = 0.05 at both time points). Carotid artery FTc had an area under the receiver operating characteristic (AUROC) curve (95% CI) of 0.70 (0.57-0.84) to predict post-induction hypotension and best cutoff value of 344.8 ms with a sensitivity and specificity of 61% and 79%, respectively. Carotid artery ðVpeak had an AUROC curve (95% CI) of 0.54 (0.39-0.69) to predict post-induction hypotension and best cutoff value of 7.9% with a sensitivity and specificity of 62% and 55%, respectively.

Conclusion

Carotid artery FTc and ðVpeak are not reasonable predictors of hypotension in patients undergoing emergency laparotomy for perforation peritonitis.

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.

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.

The use of bedside echocardiography in the care of critically ill patients - a joint consensus document of the Associação de Medicina Intensiva Brasileira, Associação Brasileira de Medicina de Emergência and Sociedade Brasileira de Medicina Hospitalar. Part 2 - Technical aspects

Echocardiography in critically ill patients has become essential in the evaluation of patients in different settings, such as the hospital. However, unlike for other matters related to the care of these patients, there are still no recommendations from national medical societies on the subject. The objective of this document was to organize and make available expert consensus opinions that may help to better incorporate echocardiography in the evaluation of critically ill patients. Thus, the Associação de Medicina Intensiva Brasileira, the Associação Brasileira de Medicina de Emergência, and the Sociedade Brasileira de Medicina Hospitalar formed a group of 17 physicians to formulate questions relevant to the topic and discuss the possibility of consensus for each of them. All questions were prepared using a five-point Likert scale. Consensus was defined a priori as at least 80% of the responses between one and two or between four and five. The consideration of the issues involved two rounds of voting and debate among all participants. The 27 questions prepared make up the present document and are divided into 4 major assessment areas: left ventricular function, right ventricular function, diagnosis of shock, and hemodynamics. At the end of the process, there were 17 positive (agreement) and 3 negative (disagreement) consensuses; another 7 questions remained without consensus. Although areas of uncertainty persist, this document brings together consensus opinions on several issues related to echocardiography in critically ill patients and may enhance its development in the national scenario.

Fluids and vasopressors in septic shock: basic knowledge for a first approach in the emergency department

Much research, both pathophysiological and clinical, has been produced about septic shock during the last 20 years. Nevertheless, many aspects of treatment are still controversial, among these the approach to the administration of fluids and vasopressors. After the first clinical trial on Early goal-directed therapy (EGDT) was published, a liberal approach to the use of fluids and conservative use of vasopressors prevailed, but in recent years a more restrictive use of fluids and an earlier introduction of vasopressors seem to be preferred. Although both treatments are based on sound pathophysiological knowledge,  clinical evidence is still inadequate and somehow controversial.  In this non-systematic review, recent research on the hemodynamics of septic shock and its treatment with fluids and inotropes is discussed. As a conclusion, general indications are proposed for a practical approach to patients in septic shock.

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.

Preanesthetic ultrasonography assessment of inferior vena cava diameter in the supine position, left lateral tilt position, and with the left uterine displacement maneuver in full-term pregnant women: A randomized cross-over design study

Preanesthetic ultrasonography assessment of inferior vena cava diameter (IVCD) in the supine position (SP), left lateral tilt position (LLT), and with the left uterine displacement maneuver (LUD) in full-term pregnant women: a randomized cross-over design study.

AIM

We pre-anesthetically measured IVCD using ultrasonography in the SP, LLT, and the LUD in full-term pregnant women, using a cross-over design, to evaluate the effectiveness of LLT and LUD on increasing IVCD, and the presence of inter-individual differences among patients in the effect of posture on IVCD.

METHODS

Twenty-two parturients scheduled for elective cesarean section under spinal anesthesia were recruited. All patients were sequentially placed in the SP, LLT, and with LUD before spinal anesthesia induction. Indices of IVCD, measured by subxiphoid ultrasonography, including maximum IVCD (IVCDmax), minimum IVCD (IVCDmin), and collapsibility index (CI) were recorded in each of the postures. Mean or median values of all measurements were compared among the postures.

RESULTS

The mean values of IVCDmax observed with both LLT and LUD were significantly larger than those in the SP, respectively (SP vs. LLT: p < 0.05, SP vs. LUD: p < 0.01), although there were no significant differences between IVCDmax with LLT and LUD. There were no significant differences in IVCDmin and CI between any of the postures. IVCDmax was highest with LUD in 11 patients (55%), in the LLT in seven patients (35%) and in the SP in two patients (10%).

CONCLUSIONS

LLT and LUD might be equally effective in enlarging the narrowed IVCD as compared to SP. However, both LLT and LUD might not necessarily be appropriate treatments to relieve IVC compression in some cases.

Effect of inferior vena cava respiratory variability-guided fluid therapy after laparoscopic hepatectomy: a randomized controlled clinical trial

BACKGROUND

After major liver resection, the volume status of patients is still undetermined. However, few concerns have been raised about postoperative fluid management. We aimed to compare gut function recovery and short-term prognosis of the patients after laparoscopic liver resection (LLR) with or without inferior vena cava (IVC) respiratory variability-directed fluid therapy in the anesthesia intensive care unit (AICU).

METHODS

This randomized controlled clinical trial enrolled 70 patients undergoing LLR. The IVC respiratory variability was used to optimize fluid management of the intervention group in AICU, while the standard practice of fluid management was used for the control group. The primary outcome was the time to flatus after surgery. The secondary outcomes included other indicators of gut function recovery after surgery, postoperative length of hospital stay (LOS), liver and kidney function, the severity of oxidative stress, and the incidence of severe complications associated with hepatectomy.

RESULTS

Compared with patients receiving standard fluid management, patients in the intervention group had a shorter time to anal exhaust after surgery (1.5 ± 0.6 days vs. 2.0 ± 0.8 days) and lower C-reactive protein activity (21.4 [95% confidence interval (CI): 11.9-36.7] mg/L vs. 44.8 [95%CI: 26.9-63.1] mg/L) 24 h after surgery. There were no significant differences in the time to defecation, serum concentrations of D-lactic acid, malondialdehyde, renal function, and frequency of severe postoperative complications as well as the LOS between the groups.

CONCLUSION

Postoperative IVC respiratory variability-directed fluid therapy in AICU was facilitated in bowel movement but elicited a negligible beneficial effect on the short-term prognosis of patients undergoing LLR.

TRIAL REGISTRATION

ChiCTR-INR-17013093.

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.

The Value of Inferior Vena Cava Ultrasonography Administration for Hypovolemia Detection in Patients with Acute Kidney Injury Hospitalized in Intensive Care Unit

Background

The hypo-perfusion of the kidneys can lead to impairment in renal function and induce renal injury in case of delayed diagnosis and treatment. To date, laboratory markers are routinely used to determine the fluid volume status of the patients. The current study aims to evaluate the values of inferior vena cava (IVC) collapsibility index in hypovolemia diagnosis among critical patients admitted at the intensive care unit (ICU).

Materials and Methods

This is a cross-sectional study performed on 67 patients admitted to the ICU due to acute kidney injury from May 2018 to October 2019. Hypovolemia was assessed assessing IVC collapsibility using ultrasonography. Laboratory data, including urine osmolality, urine-plasma creatinine ratio, sodium excretion fraction and urinary sodium level were checked. Afterward, IVC collapsibility index was measured for each patient using ultrasonography and the values of this index in accordance with the mentioned criteria was evaluated. Accordingly, reciever operating curve was depicted.

Results

There was no significant asosociation between IVC collapsibility index with fractional excretion of sodium (P = 0.69), urine Na (P = 0.93) and urine osmolality ([P = 0.09]), while urine: Plasma creatinie ration revealed a significant association with IVC collapsibility index at cut point of 40.5% with sensitivity and specificity of 96% and 44% (P = 0.017, area under the curve: 0.67, 95% confidence interval: 0.551-0.804), respectively.

Conclusion

According to the findings of this study, IVC collapsibility detected via ultrasonography was not an appropriate index to figure out hypovolemia in ICU patients. Furthermore, detailed studies are recommended.

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.

Caudal vena cava measurements and fluid responsiveness in hospitalized cats with compromised hemodynamics and tissue hypoperfusion

OBJECTIVE

To evaluate the use of the caudal vena cava collapsibility index (CVCCI) and the inspiratory/minimum and expiratory/maximum diameters of the vena cava to predict fluid responsiveness in hospitalized, critically ill cats with hemodynamic and tissue perfusion abnormalities.

DESIGN

Diagnostic test study in a prospective cohort of hospitalized cats.

SETTING

Private practice referral hospital.

ANIMALS

Twenty-four hospitalized cats with spontaneous breathing and compromised hemodynamics and tissue hypoperfusion.

INTERVENTIONS

Ultrasonographic examination before and after fluid expansion with 10 ml/kg of lactated Ringer's solution.

MEASUREMENTS AND MAIN RESULTS

Fluid responsiveness was evaluated using the velocity-time integral (VTI) of the subaortic blood flow, by measuring it before and after a fluid load of 10 ml/kg of lactated Ringer's solution. The CVCCI was calculated using the following formula: (maximum diameter - minimum diameter / maximum diameter) × 100. Ten cats were fluid responders (42 %) and 14 were nonresponders (58 %). The area under the receiver operating characteristic curve (AUROC) with their 95% confidence interval for the predictors and the best cutoff values were as follows: CVCCI, AUROC = 0.83 (0.66-1.00) and cutoff = 31%; inspiratory/minimum diameter, AUROC = 0.86 (0.70-1.00) and cutoff = 0.24 cm; expiratory/maximum diameter, AUROC = 0.88 (0.74-1.00) and cutoff = 0.22 cm. A significant lineal correlation was observed between the percentage of increase in VTI after expansion and CVCCI (r_s  = 0.68, P < 0.001), expiratory/maximum diameter (r_s  = -0.72, P < 0.001), and inspiratory/minimum diameter (r_s  = -0.71, P < 0.001). The intraobserver and interobserver variability was low for VTI, and the expiratory/maximum diameter and inspiratory/minimum diameter were high for CVCCI.

CONCLUSIONS

Caudal vena cava measurements could be useful to predict the response to fluids in hospitalized cats with hemodynamic and tissue perfusion alterations. Additional studies are required to draw definitive conclusions about the role of these variables to guide fluid administration in cats.

The effect of continuous positive airway pressure on inferior vena cava collapsibility as measured by bedside ultrasound

Objectives

The purpose of this study was to determine the impact of progressively increasing continuous positive airway pressure (CPAP) on measurements of the caval index (CI) using bedside ultrasound at the 3 common inferior vena cava (IVC) evaluation sites.

Methods

This was a prospective, observational trial that included 165 healthy adults over 18 years old enrolled between February 2015 and May 2018. Measurements of the IVC were obtained during normal tidal respirations from the subxiphoid area in the long and short axis and from the right mid-axillary line in the long axis. Measurements were obtained in each of these locations at atmospheric pressure and with CPAP at 5, 10, and 15 cmH2O. The CI was then calculated for each of the 3 selected locations at each level of pressure.

Results

As CPAP pressures increased from 0 to 15 cmH2O the CI measurements obtained at the lateral mid-axillary line did not show any statistically significant variation. There was a statistically significant difference (P < 0.001) when comparing measurements of the CI from the lateral mid-axillary line location to both anterior locations. As CPAP pressures increased, the CI calculated from the subxiphoid area in both the anterior short and anterior long axis orientations initially trended upwards at 5 cmH2O, then began to downtrend as the pressures increased to 10 and 15 cmH2O. Comparing the CI measurements from the anterior long and anterior short axis at 0, 5, 10, and 15 cmH2O, there was no statistically significant difference at any pressure (P > 0.05).

Conclusion

When evaluating the IVC in a spontaneously breathing patient, measurements from an anterior orientation are preferred as the lateral mid-axillary view can underestimate CI calculations.

Fluid challenge in critically ill patients receiving haemodynamic monitoring: a systematic review and comparison of two decades

Introduction

Fluid challenges are widely adopted in critically ill patients to reverse haemodynamic instability. We reviewed the literature to appraise fluid challenge characteristics in intensive care unit (ICU) patients receiving haemodynamic monitoring and considered two decades: 2000–2010 and 2011–2021.

Methods

We assessed research studies and collected data regarding study setting, patient population, fluid challenge characteristics, and monitoring. MEDLINE, Embase, and Cochrane search engines were used. A fluid challenge was defined as an infusion of a definite quantity of fluid (expressed as a volume in mL or ml/kg) in a fixed time (expressed in minutes), whose outcome was defined as a change in predefined haemodynamic variables above a predetermined threshold.

Results

We included 124 studies, 32 (25.8%) published in 2000–2010 and 92 (74.2%) in 2011–2021, overall enrolling 6,086 patients, who presented sepsis/septic shock in 50.6% of cases. The fluid challenge usually consisted of 500 mL (76.6%) of crystalloids (56.6%) infused with a rate of 25 mL/min. Fluid responsiveness was usually defined by a cardiac output/index (CO/CI) increase ≥ 15% (70.9%). The infusion time was quicker (15 min vs 30 min), and crystalloids were more frequent in the 2011–2021 compared to the 2000–2010 period.

Conclusions

In the literature, fluid challenges are usually performed by infusing 500 mL of crystalloids bolus in less than 20 min. A positive fluid challenge response, reported in 52% of ICU patients, is generally defined by a CO/CI increase ≥ 15%. Compared to the 2000–2010 decade, in 2011–2021 the infusion time of the fluid challenge was shorter, and crystalloids were more frequently used.

Carotid artery corrected flow time and respiratory variations of peak blood flow velocity for prediction of hypotension after induction of general anesthesia in elderly patients

Background

Postinduction hypotension is closely related to postoperative complications. Elderly patients with compromised cardiovascular compensatory reserve are more susceptible to hypotension after induction of general anesthesia. This study investigated whether the carotid artery corrected flow time (FTc) and respiratory variation of peak blood flow velocity in the common carotid artery (ΔVpeak) could predict postinduction hypotension in elderly patients.

Methods

This prospective observational study included elderly patients aged 65 to 75 who were scheduled for elective surgery under general anesthesia with ASA physical status class of I-II, without cardiovascular disease, hypertension, diabetes, or obesity. Anesthesia was induced by midazolam, sufentanil, and etomidate and was maintained by sevoflurane. The carotid artery FTc and ΔVpeak were measured by ultrasound before induction of anesthesia. Hemodynamic data were recorded before induction and then during the first 10 min after induction.

Results

Ninety-nine patients were included in the final analysis, of whom 63 developed postinduction hypotension. The area under the receiver operating characteristic curves was 0.87 (0.78 to 0.93) for carotid artery FTc and 0.67 (0.56 to 0.76) for ΔVpeak, respectively. The optimal cutoff value for predicting postinduction hypotension was 379.1 ms for carotid artery FTc, with sensitivity and specificity of 72.2 and 93.7%, respectively. The best cutoff value was 7.5% for ΔVpeak, with sensitivity and specificity of 55.6 and 75.0%, respectively.

Conclusions

The carotid artery FTc is a reliable predictor of postinduction hypotension in elderly patients with ASA status of I or II, without cardiovascular disease, hypertension, diabetes, or obesity. Elderly patients with a carotid artery FTc less than 379.1 ms before anesthesia have a higher risk of postinduction hypotension.

Trial registration

Clinical Trial Registry on August 2nd, 2020 (www.chictr.org.cn; ChiCTR2000035190).

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.

Comparison of inferior vena cava collapsibility and central venous pressure in assessing volume status in shocked patients

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An accurate diagnosis of shock state can be challenging, particularly in low-income countries, such as African countries, because physical signs of hypovolaemic, distributive, cardiogenic, and obstructive shock frequently overlap.

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Low-income countries therefore require easy and noninvasive methods, such as ultrasound devices.

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This study aims to provide an accurate estimation of intravascular volume status using bedside noninvasive methods as an essential part of the management of shocked patients.

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We discovered that the inferior vena cava collapsibility index (IVC-ci) could be a good tool with moderate reliability for detecting fluid responsiveness because it is a less invasive and fast method.

Introduction

Determination of intravascular volume status in patients admitted to the emergency centre is critical. Physical signs of hypovolaemic, distributive, cardiogenic, and obstructive shock frequently overlap, making an accurate diagnosis of shock state difficult. This is problematic because fluid loading is considered the first step in haemodynamically unstable patients’ resuscitation. Yet, multiple studies have shown that only approximately 50% of haemodynamically unstable patients in the intensive care unit and operating theatre respond to a fluid challenge. This study aims to provide an accurate estimation of intravascular volume status using bedside noninvasive methods as an essential part of the assessment of volume status in shocked patients.

Methodology

This is a cross-sectional analytical study conducted on 102 shocked patients presented to the emergency centre. IV fluid boluses were standardized to be administered at 500 mL every 30 min over 120 min, as clinically indicated. Concurrent measurements of inferior vena cava collapsibility index (IVC-ci) were performed shortly before the initiation of IV bolus (i.e., time 0), and then at 30, 90, and 120 min, we measured both venous collapsibility index (CI) and central venous pressure (CVP). At each session, we recorded patient demographics, fluid responsiveness, and vital sign assessments.

Results

We discovered that IVC-ci at cut-off point 40 has a sensitivity of 93.3% and specificity of 70.7% with an AUC of 0.908 and a good 95% CI (0.84–0.975), implying that IVC-ci of 40% or higher can indicate fluid responsiveness in shocked patients. CVP, despite having a good sensitivity of 88.6%, high specificity of 100%, and a significant p-value, is not a reliable detector of fluid responsiveness due to its small AUC value and low 95% CI.

Conclusion

IVC-ci could be a good tool with moderate reliability for detecting fluid responsiveness because it is a less invasive and fast method.

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.

Correlation of Ultrasound-Based Hydration Assessment Measures with CVP and Clinical Hydration Status among Children Admitted to the PICU: A Prospective Observational Study

Purpose This article assesses the correlation of respiratory variation in inferior vena cava (IVC) with central venous pressure (CVP) in children. Secondary objective was to evaluate IVC variability with clinical hydration status.

Methods IVC variability was assessed at the subcostal (SC) and right lateral (RL) region, and collapsibility index (CI) (spontaneously breathing) and distensibility index (DI) (positive pressure) and IVC/aortic ratio were calculated. Partial correlations were calculated between CI/DI with CVP adjusting for body mass index and age. Sensitivity of CI and DI to predict clinical dehydration was calculated using receiver operating characteristic curves.

Results A total of 145 ultrasounds were performed on 72 patients (41% positive pressure). Only RL CI in spontaneously breathing patients strongly correlated with CVP (r = –0.65, p < 0.001). A moderate correlation was observed between CI and DI from SC and RL regions (r's = 0.38 and 0.47). Among spontaneously breathing patients, a significant difference was observed in the SC CI based on hydration status. For patients on positive pressure, IVC/aortic ratio had a significant difference. SC CI had the highest area under the curve (0.82) to detect dehydration with 80% sensitivity/87% specificity for a cutoff of 40%.

Conclusion SC CI is the most reliable measure to assess the hydration status of spontaneously breathing children, while the IVC/aortic ratio performs well for patients under positive pressure. RL CI has strong negative correlation with CVP in spontaneously breathing patients.