Does respiratory variation of inferior vena cava diameter predict fluid responsiveness in spontaneously ventilating children with sepsis

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

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

Stroke volume variation induced by lung recruitment maneuver to predict fluid responsiveness in patients receiving mechanical ventilation: A systematic review and meta-analysis

STUDY OBJECTIVE

The aim of this study was to evaluate the accuracy of lung recruitment maneuver induced stroke volume variation (ΔSVLRM) in predicting fluid responsiveness in mechanically ventilated adult patients by systematic review and meta-analysis.

METHODS

A comprehensive electronic search of relevant literature was conducted in PubMed, Web of Science, Cochrane Library, Ovid Medline, Embase and Chinese databases (including China National Knowledge Infrastructure, Wanfang and VIP databases). Review Manager 5.4, Meta-DiSc 1.4 and STATA 16.0 were selected for data analysis, and QUADAS-2 tool was used for quality assessment. Data from selected studies were pooled to obtain sensitivity, specificity, diagnostic likelihood ratio (DLR) of positive and negative, diagnostic odds ratio (DOR), and summary receiver operating characteristic curve.

RESULTS

A total of 6 studies with 256 patients were enrolled through March 2024. The risk of bias and applicability concerns for each included study were low, and there was no significant publication bias. There was moderate to substantial heterogeneity for the non-threshold effect, but not for the threshold effect. The combined sensitivity and specificity were 0.84 (95% CI, 0.77-0.90) and 0.79 (95% CI, 0.70-0.86), respectively. The DOR and the area under the curve (AUC) were 22.15 (95%CI, 7.62-64.34) and 0.90 (95% CI, 0.87-0.92), respectively. The positive and negative predictive values of DLR were 4.53 (95% CI, 2.50-8.18) and 0.19 (95% CI, 0.11-0.35), respectively. Fagan's nomogram showed that with a pre-test probability of 52%, the post-test probability reached 83% and 17% for the positive and negative tests, respectively.

CONCLUSIONS

Based on the currently available evidence, ΔSVLRM has a good diagnostic value for predicting the fluid responsiveness in adult patients undergoing mechanical ventilation. Given the heterogeneity and limitations of the published data, further studies with large sample sizes and different clinical settings are needed to confirm the diagnostic value of ΔSVLRM in predicting fluid responsiveness. PROSPERO registration number: CRD42023490598.

Updates on the clinical integration of point-of-care ultrasound in pediatric emergency medicine

PURPOSE OF REVIEW

There is expanding evidence for point-of-care ultrasound (POCUS) use in pediatric emergency medicine - this review highlights the benefits and challenges in the clinical integration of high-yield POCUS applications. Specifically, it will delve into POCUS applications during resuscitations, controversies of Focused Assessment with Sonography for Trauma (FAST) in pediatric trauma, POCUS-guided procedures, and examples of clinical pathways where POCUS can expedite definitive care.

RECENT FINDINGS

POCUS can enhance diagnostic accuracy and aid in management of pediatric patients in shock and help identify reversible causes during cardiac arrest. The use of the FAST in pediatric blunt abdominal trauma remains nuanced - its proper use requires an integration with clinical findings and an appreciation of its limitations. POCUS has been shown to enhance safety and efficacy of procedures such as nerve blocks, incision & drainage, and intravenous access. Integrating POCUS into pathways for conditions such as intussusception and testicular torsion expedites downstream care.

SUMMARY

POCUS enhances diagnostic efficiency and management in pediatric patients arriving at the ED with undifferentiated shock, cardiac arrest, or trauma. Additionally, POCUS improves procedural success and safety, and is integral to clinical pathways for expediting definitive care for various pediatric emergencies. Future research should continue to focus on the impact of POCUS on patient outcomes, ensuring user competency, and the expansion of POCUS into diverse settings.

Point-of-Care Ultrasonography for the Assessment of Dehydration in Children: A Systematic Review

OBJECTIVES

Accurate estimation of the degree of dehydration remains a diagnostic challenge. The primary objective was to systematically review the literature on the role of ultrasound in assessment of the degree of dehydration in children.

METHODS

Data sources included Ovid MEDLINE, Web of Science Core Collection, Current Index to Nursing and Allied Health Literature, Cochrane Library, ClinicalTrials.gov , and Trip Pro Database. Two independent reviewers used screening protocol to include articles on assessment of dehydration in children with the use of point-of-care ultrasonography (POCUS). The level of evidence was assessed in accordance with the "The Oxford 2011 Levels of Evidence." The Quality Assessment of Diagnostic Accuracy Studies-2 tool was used to evaluate risk of bias.

RESULTS

We identified 108 studies, and 8 studies met our inclusion criteria. All studies were prospective cohort studies (level of evidence, 3-4). The authors of 5 studies used difference between ill weight and weight after rehydration as the reference standard for dehydration, and the authors of 3 studies used clinical dehydration scale. Two studies from the United States showed acceptable areas under the curve for inferior vena cava to aorta (IVC/Ao) diameter ratio at 0.72 and 0.73 for prediction of significant dehydration (>5% weight loss). The IVC/Ao ratio with cut-off at 0.8 had sensitivity of 67% and 86% and specificity of 71% and 56% for prediction of significant dehydration. Studies from the resource-limited settings were more heterogeneous. One study with acceptable risk of biases reported poor sensitivity (67%) and specificity (49%) of Ao/IVC ratio with cut-off of 2.0 for predicting severe dehydration (>9% weight loss) with area under the curve at 0.6. Three studies showed increase in IVC diameter with fluid resuscitation with mean change in IVC diameter by 30% in children with significant dehydration (>5% weight loss) and by 22% without significant dehydration (<5% weight loss). Metaanalysis was not completed due to high heterogeneity.

CONCLUSIONS

This study showed that the quantity and quality of research on the application of POCUS for the assessment of dehydration in children is limited. There is no criterion standard for assessing the degree of dehydration and no universal definition of the degree of dehydration. Thus, more methodologically rigorous studies are required. Current systematic review does not support the routine use of US to determine the severity of dehydration in children. Despite these limitations, the use of POCUS in children with dehydration demonstrates potential. Given the clear increase in IVC size with rehydration, repeated IVC US scans may be helpful in guiding fluid resuscitation in children with dehydration. From different proposed US parameters, IVC/Ao ratio has better diagnostic accuracy in detecting significant dehydration than Ao/IVC ratio and IVC collapsibility index. Despite low to moderate diagnostic performance, US still showed better assessment of dehydration than physician gestalt and World Health Organization score.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Evaluation of the Inferior Vena Cava Diameter in Dehydrated Children Using Bedside Ultrasonography

Objective

Bedside ultrasonography (US) is a new imaging modality that has begun to be used in the Pediatric Emergency Unit to evaluate inferior vena cava (IVC) diameter for intravascular volume status. In this article, we aimed to evaluate IVC diameter with bedside US before and after the fluid therapy in dehydrated children.

Methods

A total of 124 dehydrated patients were enrolled, aged 8 months to 17 years. The maximum diameters of the IVC and aorta (AO) were measured. IVC/AO ratio and IVC collapsibility index IVC–CI were calculated before and after the fluid therapy and correlation with the degree of dehydration and laboratory parameters was investigated.

Results

Of the 124 patients, 49.2% (n = 61) were male, the mean age was 7.5 ± 4.94 years. The IVC/AOs ratio was increased in mild and moderate/severe groups after fluid therapy compared to before fluid administration. While the mean rate of heart rate, blood urea nitrogen (BUN), creatinine, and uric acid values were higher in the moderate/severe group, potassium and HCO₃ were lower. There was no significant change in AO diameter and IVC–CI after fluid therapy in all groups. When the factors affecting the IVC/AOs ratio were analyzed with the logistic regression backward model; the IVC/AO ratio was found to increase as the degree of dehydration decreased (Adj.β = −0.318) and as the age (Adj.β = 0.242) and CRP (Adj.β = 0.186) value increased.

Conclusion

The IVC/AO ratio can be a promising index for the assessment and grading of dehydration in children, and cutoff values that vary according to age are necessary for a more objective assessment of dehydration.

Hemodynamic monitoring and management of pediatric septic shock

Sepsis remains a major cause of morbidity and mortality among children worldwide. Furthermore, refractory septic shock and multiple organ dysfunction syndrome are the most critical groups which account for a high mortality rate in pediatric sepsis, and their clinical course often deteriorates rapidly. Resuscitation based on hemodynamics can provide objective values for identifying the severity of sepsis and monitoring the treatment response. Hemodynamics in sepsis can be divided into two groups: basic and advanced hemodynamic parameters. Previous therapeutic guidance of early-goal directed therapy (EGDT), which resuscitated based on the basic hemodynamics (central venous pressure and central venous oxygen saturation (ScvO2)) has lost its advantage compared with “usual care”. Optimization of advanced hemodynamics, such as cardiac output and systemic vascular resistance, has now been endorsed as better therapeutic guidance for sepsis. Despite this, there are still some important hemodynamics associated with prognosis. In this article, we summarize the common techniques for hemodynamic monitoring, list important hemodynamic parameters related to outcomes, and update evidence-based therapeutic recommendations for optimizing resuscitation in pediatric septic shock.

Optimizing Fluid Resuscitation and Preventing Fluid Overload in Patients with Septic Shock

Intravenous fluid administration remains an important component in the care of patients with septic shock. A common error in the treatment of septic shock is the use of excessive fluid in an effort to overcome both hypovolemia and vasoplegia. While fluids are necessary to help correct the intravascular depletion, vasopressors should be concomitantly administered to address vasoplegia. Excessive fluid administration is associated with worse outcomes in septic shock, so great care should be taken when deciding how much fluid to give these vulnerable patients. Simple or strict "recipes" which mandate an exact amount of fluid to administer, even when weight based, are not associated with better outcomes and therefore should be avoided. Determining the correct amount of fluid requires the clinician to repeatedly assess and consider multiple variables, including the fluid deficit, organ dysfunction, tolerance of additional fluid, and overall trajectory of the shock state. Dynamic indices, often involving the interaction between the cardiovascular and respiratory systems, appear to be superior to traditional static indices such as central venous pressure for assessing fluid responsiveness. Point-of-care ultrasound offers the bedside clinician a multitude of applications which are useful in determining fluid administration in septic shock. In summary, prevention of fluid overload in septic shock patients is extremely important, and requires the careful attention of the entire critical care team.

Fifteen-minute consultation: Point of care ultrasound in the management of paediatric shock

The use of point of care ultrasound (POCUS) in the assessment of the acutely shocked adult patient has been well established for over a decade. Comparatively, its use in paediatrics has been limited, but this is starting to change with the recent introduction of Children's Acute Ultrasound training. This article highlights the pathophysiology of shock in children and demonstrates how bedside ultrasound can be used to assist decision making in the clinical assessment of the neonate, infant or older child presenting with undifferentiated shock. We discuss a structured protocol to use when performing the POCUS examination and explain how this could lead to a more rapid correlation of the ultrasound findings with the underlying cause of shock.

Functional echocardiographic preload markers in neonatal septic shock

BACKGROUND

There are no established clinical or laboratory markers of preload adequacy and fluid responsiveness in management of neonatal shock. Functional echocardiographic preload markers are evaluated in children and adults, but there is no data in neonatal septic shock. We evaluated five functional echocardiographic preload markers during intravenous volume resuscitation in neonatal septic shock.

OBJECTIVE

(1) To compare baseline functional echocardiographic preload markers between neonates with septic shock and their "matched" healthy controls. (2) To compare echocardiographic preload markers before and after intravenous volume resuscitation.

METHODS

In this cohort study, we enrolled neonates with septic shock (cases) and recorded five preload markers - inferior vena cava collapsibility index (IVC-CI), left ventricular end-diastolic (LVEDV) & end-systolic volume (LVESV) and their indices (LVEDVI, LVESVI) - before initiation of intravenous fluid resuscitation (baseline evaluation). An equal number of "matched hemodynamically stable" controls were recruited, who underwent functional echocardiographic assessment once. In neonates with shock, we recorded these markers again after volume resuscitation.

RESULTS

We analyzed 46 neonates (23 cases and 23 controls). Neonates with shock had significantly elevated baseline IVC-CI as compared to controls [53% (21, 100) vs. 20% (15, 24) respectively, p-value = .01). Rest 4 echocardiographic markers (LVEDV, LVESV, LVEDVI, and LVESVI) were comparable between cases and controls. Sixteen neonates (70% of 23) received intravenous fluid resuscitation and rest 7 (30%) were started directly on vasoactive drugs. None of the preload markers changed significantly after volume resuscitation as compared to the baseline values including IVC-CI, which was almost significant [74% (33, 100) at baseline to 48% (13, 93) after 10 mL/kg and 50% (40, 69) after 20 mL/kg, (p = .05). All preload markers were comparable between survivors and non-survivors.

CONCLUSION

Neonates with septic shock had significantly elevated IVC-CI at baseline as compared to hemodynamically stable neonates. None of the preload markers changed significantly after volume resuscitation as compared to the baseline values including IVC-CI, which was almost significant.

Central Venous Pressure Estimation by Ultrasound Measurement of Inferior Vena Cava and Aorta Diameters in Pediatric Critical Patients: An Observational Study

OBJECTIVES

To evaluate the ability to predict central venous pressure by ultrasound measured inferior vena cava and aortic diameters in a PICU population and to assess interoperator concordance.

DESIGN

Noninterventional observational study.

SETTING

PICU of a tertiary-care academic center.

PATIENTS

Eighty-eight pediatric patients (0-16 yr old) with a central venous catheter in place were studied. Sixty-nine percent of the patients received positive-pressure ventilation.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

An experienced and a nonexperienced operator used ultrasound to measure the maximal diameter of inferior vena cava and minimal diameter of the inferior vena cava and the maximum diameter of the abdominal aorta from the subxiphoid window. The inferior vena cava collapsibility index and the ratio of maximal diameter of inferior vena cava/maximum diameter of the abdominal aorta were then derived. The central venous pressure was measured using a central venous catheter and recorded. Twenty-three patients had low central venous pressure values (≤ 4 mm Hg), 35 patients a value in the range of 5-9 mm Hg, and 30 patients high values (≥ 10 mm Hg). Both inferior vena cava collapsibility index and ratio of maximal diameter of inferior vena cava/maximum diameter of the abdominal aorta were predictive of high (≥ 10 mm Hg) or low (≤ 4 mm Hg) central venous pressure. The test accuracy showed the best results in predicting low central venous pressure with an inferior vena cava collapsibility index greater than or equal to 35% and ratio of maximal diameter of inferior vena cava/maximum diameter of the abdominal aorta less than or equal to 0.8, and in predicting high central venous pressure with an inferior vena cava collapsibility index less than or equal to 20% and ratio of maximal diameter of inferior vena cava/maximum diameter of the abdominal aorta greater than or equal to 1.3. Inferior vena cava collapsibility index returned generally higher accuracy values than ratio of maximal diameter of inferior vena cava/maximum diameter of the abdominal aorta. Lin's coefficient of concordance between the operators was 0.78 for inferior vena cava collapsibility index and 0.86 for ratio of maximal diameter of inferior vena cava/maximum diameter of the abdominal aorta.

CONCLUSIONS

Inferior vena cava collapsibility index and ratio of maximal diameter of inferior vena cava/maximum diameter of the abdominal aorta correlate well with central venous pressure measurements in this PICU population, and specific inferior vena cava collapsibility index or ratio of maximal diameter of inferior vena cava/maximum diameter of the abdominal aorta thresholds appear to be able to differentiate children with high or low central venous pressure. However, the actual clinical application of these statistically significant results remains limited, especially by the intrinsic flaws of the procedure.

Comparison of Respiratory Variations of Subclavian Vein and Inferior Vena Cava in Hospitalized Patients with Kidney Disease

Background

Accurate assessment of relative intravascular volume is critical for appropriate volume management of patients with kidney disease. Respiratory variations of inferior vena cava (IVC) diameter have been used and may correlate with those of subclavian vein (SCV) by bedside ultrasound. The purpose of this study was to assess the relationship between SCV and IVC respiratory variations by bedside ultrasound in a large group of hospitalized patients with acute and/or chronic kidney disease.

Methods

We compared 160 paired SCV and IVC bedside ultrasound studies from 102 semi-recumbent hospitalized adult patients with kidney disease. Patient encounters in which the SCV or IVC could not be clearly visualized were excluded. Collapsibility index=(Dmax–Dmin)/Dmax*100%; D=venous diameter.

Results

Relationships between SCV collapsibility index and IVC collapsibility index were not different for longitudinal and transverse views of the SCV. Correlation of SCV collapsibility index with IVC collapsibility index was 0.75 for mechanical ventilation (n=65, P<0.0001) and 0.67 for spontaneous breathing (n=95, P<0.0001). IVC collapsibility index cut-offs <20% for hypervolemia and >50% for hypovolemia corresponded to SCV collapsibility index cut-offs of <22% and >39%, respectively, for both mechanical ventilation and spontaneous breathing encounters. Using these cut-offs for SCV collapsibilities, assessment as hypervolemia versus not-hypervolemia had maximal sensitivity and specificity for predicting respective IVC collapsibility cut-offs of 88% for mechanical ventilation and 74% for spontaneous breathing, and assessment as hypovolemia versus not-hypovolemia had maximal sensitivity and specificity of 91% and 70%, respectively. Concordance, defined as agreement between assessment using SCV CI and assessment using IVC CI, was 85% for mechanical ventilation and 72% for spontaneous breathing when differentiating hypervolemia versus not-hypervolemia and was 89% and 71% respectively when differentiating hypovolemia versus not-hypovolemia.

Conclusion

Assessment using SCV collapsibility index in the semi-recumbent position has a reasonable concordance with assessment using IVC collapsibility index for both spontaneous breathing and mechanical ventilation, in a wide range of hospitalized patients with concurrent kidney disease, and may be a useful adjunct to assess relative intravascular volume in patients with kidney disease.

Caudal vena cava collapsibility index as a tool to predict fluid responsiveness in dogs

OBJECTIVE

To evaluate the use of the caudal vena cava collapsibility index (CVCCI) as a predictor of fluid responsiveness in hospitalized, critically ill dogs with hemodynamic or tissue perfusion abnormalities.

DESIGN

Retrospective observational study.

SETTING

Private referral center.

ANIMALS

Twenty-seven critically ill, spontaneously breathing dogs with compromised hemodynamics or tissue hypoperfusion.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The electronic medical records were searched for dogs admitted for any cause, from August 2016 to December 2017. We included dogs with ultrasound measurements of: CVCCI, performed at baseline; and velocity time integral (VTI) of the subaortic blood flow, carried out before and after a fluid load. CVCCI was estimated as: (maximum diameter-minimum diameter/maximum diameter) × 100. Dogs in which VTI increased ≥15% were considered fluid responders. The CVCCI accurately predicted fluid responsiveness with an area under the receiver operating characteristic curve of 0.96 (95% CI, 0.88 to 1.00). The optimal cut-off of CVCCI that better discriminated between fluid responders and nonresponders was 27%, with 100.0% sensitivity and 83.3% specificity. At baseline, fluid responders had lower VTI (5.48 [4.26 to 7.40] vs 10.61 [7.38 to 13.23] cm, P = 0.004) than nonresponders. The basal maximum diameter of the caudal vena cava adjusted to body weight was not different between responders and nonresponders (0.050 [0.030 to 0.100] vs 0.079 [0.067 to 0.140] cm/kg, P = 0.339). The increase in VTI was related to basal CVCCI (R = 0.60, P = 0.001). Bland-Altman analysis showed narrow 95% limits of agreement between measurements of CVCCI and VTI performed by different observers or by the same observer.

CONCLUSIONS

The results of this small cohort study suggest that CVCCI can accurately predict fluid responsiveness in critically ill dogs with perfusion abnormalities. Further research is necessary to extrapolate these results to larger populations of hospitalized dogs.

Ultrasonographic inferior vena cava collapsibility and distensibility indices for detecting the volume status of critically ill pediatric patients

Especially in recent years, the use of point-of-care ultrasound by non-radiologist clinicians has become widespread. Point-of-care ultrasound provides rapid responses to the problems of critically ill patients at the bedside. This technique has many important advantages, including being non-invasive, cheap, repeatable, painless, and radiation-free. Numerous studies have revealed the most important clinical benefits of point-of-care ultrasound use by pediatric intensive care providers. The inferior vena cava is a vessel that is highly sensitive to fluid changes. The inferior vena cava diameter can be measured by a point-of-care ultrasound, and represents a critical parameter in assessing the patient’s fluid status. The inferior vena cava collapsibility index (in spontaneously breathing patients) and the inferior vena cava distensibility index (in mechanically ventilated patients) are calculated by determined formulas by using maximum and minimum diameters of the inferior vena cava. The indices are important guides for pediatric intensive care providers for managing their patients’ fluid treatment. Although some authors claim it is not a reliable method, the technique is coming to fore in intensive care units day by day, and has an increasing trend among pediatric intensive care specialists. Here, we aim to give detailed information on the ultrasonographic inferior vena cava diameter measurement methods, and calculations of the inferior vena cava collapsibility index and inferior vena cava distensibility index, and emphasize the importance of a noninvasive, bedside, and objective method of detecting the volume status of critically ill patients for pediatric intensive care specialists according to the published literature.

Comparison of cardiac output, IVC diameters and lactate levels in prediction of mortality in patients in emergency department; An observational study

Objective:

Fluid overload is an independent marker for mortality in critically ill patients. Assessment of fluid status and fluid responsiveness is crucial for the management of these patients. In this study, we compared the lactate level, inferior vena cava (IVC) diameter and non-invasive cardiac output (CO) monitoring in prediction of mortality in emergency department.

Methods:

This was a cross sectional observational study which comprised of 68 patients and was performed in ED of Tabriz University of Medical Sciences, Iran, from Sept 2016 until Sept 2017. IVC diameter was measured before the P-wave on ECG to avoid interference with a-wave and v-wave on the venous pressure curve, and during maximal inspiration and expiration to avoid Valsalva-like maneuvers. An arterial lactate sample was taken from all patients before performing the initial resuscitation. All patients underwent non-invasive CO monitoring by CO₂ rebreathing technique. Mortality was noted on day 28.

Results:

Deceased patients had a significantly low level of IVC diameters, less CO values and more lactate levels. However, based on ROC curve analysis, the prediction accuracy and validity of both CO values obtained by rebreathing CO₂ and IVC diameter was poor and the highest accuracy was obtained by lactate level assessment.

Conclusion:

Initial lactate value is a reliable parameter for prediction of mortality in non-traumatic critically ill patients. IVC diameter changes during spontaneous ventilation and non-invasive CO monitoring does not possess acceptable accuracy for prediction of mortality in these patients.

Inferior Vena Cava Ultrasound in Children: Comparing Two Common Assessment Methods

OBJECTIVES

Inferior vena cava ultrasound has been used as a predictor of fluid responsiveness in children. Two ultrasonographic modes can be used to measure the respiratory variation of inferior vena cava diameter: M-mode and B-mode. Inconsistencies in measurements between the modes can result in inaccuracies in commonly used indices that assess fluid responsiveness. Our primary objective was to determine whether there are differences in the ultrasound-based measurements between these two modes of evaluation, which would impact respiratory variation of inferior vena cava diameter calculation. Our secondary objective was to assess inferior vena cava displacements during the respiratory cycle as a possible mechanism for measurement differences between the modes.

DESIGN

Prospective observational study.

SETTING

PICU of a tertiary care teaching hospital.

PATIENTS

Seventy-three children under controlled ventilation (median age of 16 mo and weight of 10 kg).

INTERVENTIONS

The inferior vena cava diameters were measured using a longitudinal view using B- and M-mode ultrasound. Two respiratory variation of inferior vena cava diameter indices were evaluated: distensibility and respiratory variation. Maximum craniocaudal and mediolateral displacements of the inferior vena cava were measured using the B-mode ultrasound.

MEASUREMENTS AND MAIN RESULTS

Maximum diameters of the inferior vena cava were similar between the B- and M-modes (7.90 vs 7.90 mm, respectively; p = 0.326), but minimum diameters were smaller when measured by M-mode (6.36 vs 5.00 mm; p = 0.003). When calculated by data obtained from M-mode, respiratory variation of inferior vena cava diameter indices presented significantly higher values compared to B-mode measures (p ≤ 0.001, for both). Median inferior vena cava displacements were 5.00 mm (interquartile range, 3.68-6.26 mm) in the craniocaudal and 0.80 mm (interquartile range, 0.12-1.23 mm) in the mediolateral directions.

CONCLUSIONS

There is a significant difference between measurements of the minimum inferior vena cava diameter observed in M- and B-mode ultrasound during the respiratory cycle in children under controlled ventilation. This results in imprecise respiratory variation of inferior vena cava diameter indices. Displacements of the inferior vena cava during the respiratory cycle may influence the reliability of ultrasonographic measurements, particularly in M-mode.

Fluid responsiveness in the pediatric population

It is challenging to predict fluid responsiveness, that is, whether the cardiac index or stroke volume index would be increased by fluid administration, in the pediatric population. Previous studies on fluid responsiveness have assessed several variables derived from pressure wave measurements, plethysmography (pulse oximeter plethysmograph amplitude variation), ultrasonography, bioreactance data, and various combined methods. However, only the respiratory variation of aortic blood flow peak velocity has consistently shown a predictive ability in pediatric patients. For the prediction of fluid responsiveness in children, flow- or volume-dependent, noninvasive variables are more promising than pressure-dependent, invasive variables. This article reviews various potential variables for the prediction of fluid responsiveness in the pediatric population. Differences in anatomic and physiologic characteristics between the pediatric and adult populations are covered. In addition, some important considerations are discussed for future studies on fluid responsiveness in the pediatric population.

Cardiac and lung point-of-care ultrasound in pediatric anesthesia and critical care medicine: Uses, pitfalls, and future directions to optimize pediatric care

Point-of-care ultrasound (POCUS) has found many relevant applications in pediatric anesthesia and critical care medicine. Specifically, the cardiac and pulmonary POCUS examinations provide a wealth of information from physical examination assistance to diagnostic evaluation and assessment of treatment response. However, as with any adjunct, potentially dangerous pitfalls exist when POCUS is performed, interpreted, and applied by the novice sonographer. Using case illustrations, we highlight the clinical application of POCUS in addition to potential dangers. Additionally, suggestions for learning POCUS, assessing competency and credentialing are reviewed.

Getting to know a familiar face: Current and emerging focused ultrasound applications for the perioperative setting

Ultrasound technology is available in many pediatric perioperative settings. There is an increasing number of ultrasound applications for anesthesiologists which may enhance clinical performance, procedural safety, and patient outcomes. This review highlights the literature and experience supporting focused ultrasound applications in the pediatric perioperative setting across varied disciplines including anesthesiology. The review also suggests strategies for building educational and infrastructural systems to translate this technology into clinical practice.

Inferior vena cava, abdominal aorta, and IVC-to-aorta ratio in healthy Caucasian children: Ultrasound Z-scores according to BSA and age

The pediatric ultrasound measurement of the inferior vena cava (IVC) and aorta (AO) with the study of the collapsibility index (CI) and of IVC-to-AO ratio (IVC/AO) can provide clinicians in the acute care setting with information on abnormal volume status but one of the major limitations is a lack of reference normal values by body surface area (BSA) and age. The aim of this study was to provide reference ranges for the sonographic measurement of IVC, AO, and IVC/AO ratio in healthy Caucasian Italian children.

METHODS

We enrolled prospectively 516 healthy Caucasian Italian children aged between 1 month and 16 years. Echocardiographic IVC and AO diameters were collected and presented separately for children aged ≤1 year and for children aged over 1 year. For children >1 year we categorized subjects into 3 years classes. CI and IVC/AO for the systolic aortic diameter were then calculated. For children over 1 year, age reference ranges were age-related or BSA-related; for children of ≤1 year, reference ranges were determined with their 90% confidence intervals regardless of age and of BSA.

RESULTS

Tables and charts with reference ranges for all the echocardiographic measurements are presented for children aged >1 year according to age and BSA. The equations to obtain percentile and Z-score for each echocardiographic measurement are provided. The reference ranges for children aged ≤1 year are shown considering the small 90% confidence intervals for upper and lower limits. CI was 30% (SD 17%) in children >1 year and 36% (SD 16%) in children <1 year. IVC/AOs showed age-dependent values from 0.83 (SD 0.20) age <1 year to 1.22 (SD 0.31) in older subjects.

CONCLUSIONS

We report reliable reference ranges for echocardiographic measurement of IVC, AO, CI, and IVC/AO for a Caucasian Italian healthy pediatric population.