Inferior Vena Cava Measurements Research Articles

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

Three-Dimensional inferior vena cava for assessing central venous pressure in patients with cardiogenic shock

Evaluation of central venous pressure (CVP) by inferior vena cava (IVC) measurements is crucial in the management of patients with cardiogenic shock to optimize drugs therapy. IVC has a complex 3-dimensional (3D) shape but measurements used to estimate CVP remain based on 2-dimensional (2D) echocardiographic imaging. The aim of this study was to investigate the accuracy of CVP estimation by IVC size and collapsibility index obtained using 3D-echocardiography compared with 2D in patients with cardiogenic shock. Eighty consecutive echocardiographic examinations performed in 33 patients (72 ± 15 years, left ventricular ejection fraction = 19 ± 10%) admitted for cardiogenic shock were prospectively included. Two and three-dimensional images of the IVC, performed at baseline and when CVP was ≤ 10 mmHg, were acquired simultaneous with invasive measurement of CVP, both at rest and during sniff test. 2D and 3D IVC diameters, 3D IVC area and collapsibility index (IVCCI) were assessed. The eccentricity index (EI) was computed from 3D data as the ratio of maximum over minimum IVC diameter. The cut-off value of 10 mmHg of CVP defined patient with euvolemia hemodynamic status. At rest, the IVC diameter averaged 23 ± 7 mm by 2D and 25 ± 8 × 19 ± 7 mm by 3D. IVC had an eccentric shape (EI = 1.3) that increased when CVP was ≤10 mmHg and during sniff test ( P < 0.001). IVC measurements by 2D and 3D were correlated with CVP. The best correlation was obtained with IVCCI derived from 2D diameters (R = -0.69) and 3D areas (R = −0.82). Using the cutoff value of 50% for IVCCI, a discrepancy between invasive CVP measurements and IVCCI has been observed for 11 examinations (13%) by 2D but only one was misclassified by 3D. Inter and intra-observer reproducibility for IVC area was 7 ± 6% and 5 ± 3%, respectively ( Fig. 1 ). In patients with cardiogenic shock, IVCCI from area by 3D echocardiography is reproducible and accurate to evaluate CVP.

Inferior vena cava diameter measurements and BUN/creatinine values to determine dehydration in patients with hip fractures preoperatively: A prospective observational study.

Dehydration is a common problem in patients undergoing hip fracture surgery. Sonographic inferior vena cava (IVC) diameter measurement evaluates to estimate volume status. The aim of the study to evaluate the relationship between IVC measurements (expiratory diameter of IVC, collabsibility index [CI], inspiratory diameter of IVC) and blood urea nitrogen (BUN)/creatinine ratio in patients undergoing hip fracture surgery. Ultrasonography of IVC was performed on 35 patients underwent hip fracture surgery. The end-expiratory diameter of IVC, end-inspiratory diameter of IVC, and CI were assessed preoperatively. The patients were classified as group 1 for BUN/Cr ratio <20, group 2 for BUN/Cr ratio of >20. Sonographic IVC measurement was not successful in 14.2% of patients and 30 patients remained. The mean age was 80.43 ± 11.10 (58–95) years. The IVC diameter values had no discriminatory value for the prediction of dehydration according to BUN/creatinine ratio (P > .05). Receiver operating characteristic curve indicated that area under the curve (AUC) for CI: 49.5%, (95% CI 26.5–72.5) P > .05; for IVC inspiratory diameter: AUC: 43.3%, (95% CI, 19.9–66.6) P > .05; for IVC expiratory diameter: AUC: 45.5%, (95% CI, 26.6–65.4) P > .05. No correlations of BUN/creatinine ratio with CI and IVC expiratory diameter were found (as r = −0.262 [P = .163]; [r = 0.206, P = .274]; respectively). There were not any correlation in linear regression analysis model between BUN/Cr ratio according to independent variables (Age, CI, IVCmax, IVCmin) (P = .108, P = .419, P = .282, P = .257; respectively). No discriminatory relationship was found between the bedside ultrasonographic measurement of IVC parameters and BUN/creatinine ratio in patients underwent hip fracture surgery to predict the preoperative dehydration.

Age-Related Changes in Inferior Vena Cava Dimensions among Children and Adolescents with Syncope

To test the hypothesis that increased venous compliance manifested as inferior vena cava (IVC) dilation is an important substrate for syncope in children. IVC diameters were measured in 191 children and adolescents with syncope and in 95 controls. Subjects were divided based on age <12 years (younger group) and ≥12 years (older group). IVC measurements at the right atrial junction (IVC-RA), 10 mm below the IVC-RA junction (IVC-RA10), and at the point of maximal diameter (IVCmax) were made. The linear relation to body surface area (BSA) was confirmed, as were dimensions indexed to BSA (iIVC). Relationships between iIVC and the time of day were evaluated. In the syncope group, the mean age was 12.9 ± 3.6 years, mean weight was 54.7 ± 23 kg, and mean BSA was 1.5 ± 0.4 m2. Among controls, all IVC dimensions varied linearly with BSA (P < .001). In the older group (140 patients with syncope and 60 controls), all iIVC dimensions were larger in the syncope cohort: iIVC-RA, 9 vs 7.7 mm/m2 (P < .0001); iIVC-RA10, 9.4 vs 8.1 mm/m2 (P < .0001); iIVCmax, 11.7 vs 10.6 mm/m2 (P = .002). In the younger group (51 patients with syncope and 35 controls), there were no differences in iIVC measurements between the syncope cohort and controls: iIVC-RA, 10.2 vs 11.3 mm/m2; iIVC-RA10, 11.7 vs 12.0 mm/m2; iIVCmax, 14.2 vs 14.7 mm/m2 (P > .05 for all). The IVC is enlarged in teenagers with syncope compared with controls, suggesting that venous capacitance and resultant pooling play roles in the pathogenesis of syncope. In contrast, younger children with syncope do not demonstrate IVC dilation, suggesting that their syncope arises from a different mechanism.

COMPARISON OF INFERIOR VENA CAVA ASSESSMENT BY 2-DIMENSIONAL AND M-MODE ECHOCARDIOGRAPHY FOR THE EVALUATION OF RIGHT ATRIAL PRESSURE

Echocardiographic estimation of right atrial pressure (RAP) is used to assess intravascular volume, is a marker of prognosis in patients with cardiovascular disease, and is an essential component of the Doppler echo measurement of pulmonary artery pressure. Current guidelines recommend measuring the diameter and collapsibility of the inferior vena cava (IVC) to assign a value for RAP but do not explicitly state whether 2-dimensional (2D) or M-mode (MM) echocardiography should be used. This has resulted in variations in clinical practice among centres. We sought to determine if MM and 2D techniques differ in their evaluation of RAP using current recommendations. 2D and MM images of the IVC were prospectively acquired by sonographers in 100 clinical echocardiograms performed on non-ventilated patients over a four-week period. Two reviewers independently assessed the 2D and MM images of the IVC and made guideline-based measurements of the diameter and collapsibility. Quality of MM cursor positioning was documented. RAP was classified as normal (3 mmHg), intermediate (8 mmHg), or high (15 mmHg) based on IVC diameter and collapsibility for the MM and 2D techniques. IVC measurements were larger by MM than 2D (IVC diameter 1.82±0.51 vs. 1.70±0.49 cm, p<0.001), and agreement between MM and 2D on the presence of IVC dilation was significantly influenced by the quality of M-mode cursor positioning (χ2=9.6582, p=0.002). IVC collapsibility was also greater by MM than 2D (61±20% vs. 55±22%, p=0.001). The agreement of MM- and 2D-derived RAP values was only moderate-good (74% agreement, weighted kappa 0.61) with no indication that one technique consistently overestimated or underestimated RAP relative to the other. In the subset of patients with MM RAP derived from an improperly positioned MM cursor (n=24), agreement between 2D and MM RAP was worse (58% agreement, weighted kappa 0.39, p=0.055 for interaction between MM cursor positioning and RAP agreement). Interobserver agreement for RAP was similar for 2D (weighted kappa=0.67) and MM (weighted kappa=0.69). IVC size and collapsibility differed when evaluated by MM and 2D techniques and resulted in discrepant assessments of RAP in 26% of patients. Quality of the MM cursor positioning was a predictor of the agreement between MM and 2D IVC size and tended to affect the RAP ultimately assigned. This study suggests that discrepant measurements of RAP using MM and 2D techniques are common in clinical practice, but can be minimized by ensuring proper MM techniques are employed.

Three-Dimensional Ultrasound Imaging of Inferior Vena Cava Outperforms Standard Two-Dimensional Imaging as a Diagnostic Tool in Heart Failure

Background Right atrial pressure (RAP) and intravascular volume status are estimated by echocardiography with 2D imaging of inferior vena cava (IVC) diameter and collapsibility. 3D imaging can avoid misalignment and likely achieve more accurate length measurements. We sought to compare the diagnostic performance of 2D- and 3D-derived IVC measurements with regard to clinical parameters associated with heart failure (HF). We also assessed the degree of discordance between the two methods. Methods 200 patients had 2D and 3D subcostal IVC imaging performed before and after inspiratory sniff. Images were acquired using Philips iE33 and EPIQ7 systems and analyzed using QLAB v10.3 (Andover, MA). RAP was categorized as normal, mildly elevated, or elevated according to 2015 ASE guidelines. The reference 2D diameter limit was 2.1 cm and corresponding 3D-derived cross-sectional major axis (2.7 cm) and minor axis (1.9 cm) limits were obtained by regression analysis. Collapsibility index (CI) was calculated along each 2D and 3D axis direction. Sphericity index (SI) was calculated as the ratio of minor to major axis lengths and IVCs were categorized as either spherical (SI ≥ 0.7) or elliptical (SI Results 2D IVC diameter was 2.0 ± 0.6 cm, while 3D major and minor axes were 2.7 ± 0.7 cm and 1.9 ± 0.6 cm. 2D RAP category concordance with 3D major and minor axis RAP categories was 43% and 63%, respectively. CI was different along 3D major (44 ± 19%) and minor axes (52 ± 21%; p Table 1 . Conclusions Echocardiographic 2D- and 3D-derived categorization of RAP was discordant in roughly half of the analyzed cases. Collapsibility differs along the major and minor axes of the IVC. Vessel sphericity influences the discrepancies between 2D and 3D measurements. Furthermore, 3D cross-sectional IVC area outperformed standard 2D IVC diameter for predicting certain clinical variables. Since the IVC is typically dynamic and often non-cylindrical in shape, cross-sectional measurements by 3D imaging may provide greater fidelity in classifying RAP.

Pre-procedural CT angiography inferior vena cava measurements: a predictor of mortality in patients undergoing transcatheter aortic valve implantation.

To assess the value of pre-procedural computed tomography angiography (CTA) measurements of the suprahepatic inferior vena cava (IVC) to detect elevated central venous pressure (CVP) assessed by right heart catheterisation (RHC), and to predict post-procedural 1-year mortality in a cohort of patients undergoing transcatheter aortic valve implantation (TAVI). We retrospectively evaluated 408 consecutive patients undergoing CTA before TAVI between January 2011 and December 2014. Two hundred and five patients were included in the RHC cohort, who underwent RHC and CTA within ≤1 day prior to TAVI. Two hundred and three patients not fulfilling this requirement were included in the validation cohort. Measurements of the IVC were performed between diaphragm and right atrium on axial slices. Receiver operating characteristic (ROC) analyses, Kaplan-Meier analyses and Cox regression analyses were performed. In the RHC cohort, ROC curve analyses for IVC area measurements indicated an AUC of 0.77 (p < 0.001) to detect CVP ≥10mmHg and an area under the ROC curve (AUC) of 0.72 (p < 0.001) to predict 1-year mortality. An IVC area cut-off of ≥665 mm2 predicted 1-year mortality with a specificity of 84% and a sensitivity of 63%. Kaplan-Meier analysis showed that patients with an IVC area ≥665 mm2 had a significantly higher post-procedural 1-year mortality (38% versus 7%, log-rank p < 0.001) with a hazard ratio of 5.5 (95% CI, 2.2-13.6; p < 0.001). Applying this cut-off value to the validation cohort confirmed a significantly higher 1-year mortality after TAVI (34% versus 11%; log-rank p = 0.004) for patients with an IVC area ≥665 mm2. Pre-procedural enlargement of the suprahepatic IVC is a predictor of post-procedural 1-year mortality in patients evaluated for TAVI. • IVC measurements are moderate predictors of an elevated CVP in TAVI patients. • Pre-procedural IVC enlargement is a predictor of 1-year mortality after TAVI. • IVC enlargement is associated with right heart dysfunction in TAVI patients.

Three-Dimensional Inferior Vena Cava for Assessing Central Venous Pressure in Patients with Cardiogenic Shock

The inferior vena cava (IVC) has a complex three-dimensional (3D) shape, but measurements used to estimate central venous pressure (CVP) remain based on two-dimensional (2D) echocardiographic imaging. The aim of this study was to investigate the accuracy of IVC size and collapsibility index obtained by 3D echocardiography for assessing CVP in patients with cardiogenic shock. Eighty consecutive echocardiographic examinations performed in 33 patients (mean age, 72±15years; mean left ventricular ejection fraction, 19±10%) admitted for cardiogenic shock were prospectively included. Two-dimensional and 3D images of the IVC were acquired simultaneously with invasive measurement of CVP, both at rest and during a sniff test. IVC diameters, 3D IVC area, and IVC collapsibility index (IVCCI) were assessed. The eccentricity index was computed from 3D data as the ratio of maximum to minimum IVC diameter. A cutoff value of 10mm Hg for CVP defined patients with euvolemic hemodynamic status. At rest, IVC diameter averaged 23±7mm by 2D imaging and 25±8×19±7mm by 3D imaging. The IVC had an eccentric shape (eccentricity index=1.3) that increased when CVP was ≤10mm Hg and during the sniff test (P<.001). IVC measurements by 2D and 3D imaging were correlated with CVP. The best correlation was obtained with IVCCI derived from 2D diameters (R=-0.69) and 3D areas (R=-0.82). Using a cutoff value of 50% for IVCCI, 11 examinations were misclassified by 2D imaging and only one by 3D imaging. Inter- and intraobserver reproducibility for IVC area was 7±6% and 5±3%, respectively. In patients with cardiogenic shock, IVCCI from area by 3D echocardiography is reproducible and accurate to evaluate CVP.

Preoperative and Postoperative Assessment of Ultrasonographic Measurement of Inferior Vena Cava: A Prospective, Observational Study.

Background: Ultrasound measurement of dynamic changes in inferior vena cava (IVC) diameter and collapsibility index (CI) are used to estimate the fluid responsiveness and intravascular volume status. We conducted an analysis to quantify the sonographic measurement of IVC diameter changes in adult patients at the preoperative and postoperative periods. Methods: Ultrasonography was performed on 72 patients scheduled for surgery with American Society of Anesthesiologists physical status I to III. Quantitative assessments of the end-expiration (Dmin), end-inspiration (Dmax), and CI at preoperative and postoperative period were compared in a prospective, observational study. The patients received intravenous fluid according to standard protocol regimes peroperatively. Results: Ultrasonography of IVC measurement was unsuccessful in 12.5% of patients and 63 patients remained for analyses. The mean age was 43.29 ± 17.22 (range 18–86) years. The average diameter of the Dmin, Dmax, and dIVC preoperative and postoperative were 1.99 ± 0.31 vs. 2.05 ± 0.29 cm, 1.72 ± 0.33 vs. 1.74 ± 0.32 cm, 14.0 ± 9.60% vs. 15.14 ± 11.18%, respectively (p > 0.05). CI was positively associated preoperatively and postoperatively (regression coefficient = 0.438, p < 0.01). Conclusion: The diameter of the IVC did not change preoperatively and postoperatively in adult patients with standard fluid regimens. The parameters of the IVC diameter increased postoperatively according to the preoperative period.

Automated Identification and Localization of the Inferior Vena Cava Using Ultrasound: An Animal Study.

Ultrasound measurement of the inferior vena cava (IVC) is widely implemented in the clinic. However, the process is time consuming and labor intensive, because the IVC diameter is continuously changing with respiration. In addition, artificial errors and intra-operator variations are always considerable, making the measurement inconsistent. Research efforts were recently devoted to developing semiautomated methods. But most required an initial identification of the IVC manually. As a first step toward fully automated IVC measurement, in this paper, we present an intelligent technique for automated IVC identification and localization. Forty-eight ultrasound data sets were collected from eight pigs, each of which included two frames in B-mode and color mode (C-mode) collected at the inspiration, and two cine loops in B-mode and C-mode. Static and dynamic automation algorithms were applied to the data sets for identifying and localizing the IVC. The results were evaluated by comparing with the manual measurement of experienced clinicians. The automated approaches successfully identified the IVC in 47 cases (success rate: 97.9%). The automated localization of the IVC is close to the manual counterpart, with the difference within one diameter. The automatically measured diameters are close to those measured manually, with most differences below 15%. It is revealed that the proposed method can automatically identify the IVC with high success rate and localize the IVC with high accuracy. But the study with high accuracy was conducted under good control and without considering difficult cases, which deserve future explorations. The method is a first step toward fully automated IVC measurement, which is suitable for point-of-care applications.

ASSESSMENT OF RIGHT ATRIAL PRESSURE IN CHILDREN WITH CONGENITAL HEART DISEASE: SIMULTANEOUS THREE-DIMENSIONAL ECHOCARDIOGRAPHY AND CATHETERIZATION STUDY

Echocardiographic estimation of right atrial pressure (RAP) using inferior vena cava (IVC) dimensions and its collapsibility in children remains controversial. To access IVC measurements without the influence of translation of IVC into another plane during respiration is essential but challenging.

459: Sonographically measured inferior vena caval diameter in response to different maternal positions in pregnancy

Placing pregnant patients in left lateral tilt (LLT) position to avoid compression of the inferior vena cava (IVC) has long been standard obstetric practice. The American Heart Association recommends continuous manual left uterine displacement (LUD) instead of LLT position during a maternal cardiac arrest. The relationship between maternal position and proximal filling of the IVC is unknown. The hypothesis is that the maternal IVC diameter would increase in response to LLT and LUD compared to supine position. A pilot prospective observational study was performed on 60 healthy gravidas. 30 patients at 20-24 weeks and 30 patients at 37-41 weeks were recruited. Patients were placed in supine, 30 degree left lateral tilt and supine with left uterine displacement positions. The IVC was visualized by ultrasound using the subxiphoid technique. The primary outcome was IVC diameter at end expiration. Descriptive analysis and student's paired t-test were performed. In the 20-24 weeks cohort, patients in LLT position (77.5 +/- 9.8, p=0.03) and LUD position (77.3 +/-9.5, p=0.04) had a significant decrease in heart rate (bpm) compared to supine position (80.5 +/-8.5). Patients in the LUD position (80.7 +/-7.6, p<0.001) had a significant decrease in MAP compared to supine position (83.7 +/- 7.4). No significant differences were seen in the IVC diameter between all 3 positions.In the 37-41 weeks cohort, there were no significant differences in the MAP, heart rate, and IVC measurement between all 3 positions.In the 20-24 weeks cohort, 48.3%, 30%, 18.3% of patients had their largest IVC diameter in the LUD, LLT, and supine position, respectively. In the 37-41 weeks cohort, 33.3%, 28.3%, 30% of patients had their largest IVC diameter in the LUD, LLT, and supine position, respectively. 1 subject in each cohort experienced symptoms consistent with supine hypotension syndrome in the supine position (3.33%). Sonographically the IVC diameters were not statistically different between all 3 positions. Furthermore, 18% in the 20-24 weeks cohort and 30% in the 37-41 weeks cohort had their largest IVC diameter in the supine position. This observation challenges the universal belief of uterine IVC compression with associating decrease in proximal IVC filling among pregnant cohort. This study suggests that LLT or LUD may not be universally beneficial.

Fluid status evaluation by inferior vena cava diameter and bioimpedance spectroscopy in pediatric chronic hemodialysis

BackgroundEvaluation of patient’s dry weight remains challenging in chronic hemodialysis (HD) especially in children. Inferior Vena Cava (IVC) measurement was reported useful to assess fluid overload both in adults and children.MethodsWe performed a monocentric prospective study to evaluate the relation between predialytic IVC diameter measurements and hydration status evaluated by physicians and bioimpedance spectroscopy (BIS) and between IVC measurements and persistent hypertension.ResultsForty-eight HD sessions in 16 patients were analyzed. According to physicians, patients were overhydrated in 84.5% of dialysis sessions, 20.8% according to BIS, and 0%, 4.1% and 20.8% according to IVC inspiratory, expiratory and collapsibility index reference curves respectively. There was no correlation between relative overhydration evaluated by BIS and IVC measurements z-scores (p = 0.20). Patients whose blood pressure normalized after HD had a more dilated maximal IVC diameter before dialysis session than patients with persistent hypertension (median − 0.07SD [−0.8; 0.88] versus −1.61SD [−2.18; −0.74] (p = 0.03)) with an optimal cut-off of −0.5 SD.ConclusionsIn our study, IVC measurement is not reliable to assess fluid overload in children on HD and was not correlated with extracellular fluid volume assessed by BIS measurements. However, IVC measurements might be of interest in differentiating volume-dependant hypertension from volume-independant hypertension.

Volume Assessment by Inferior Vena Cava Examination: Bedside Ultrasound Techniques and Practical Difficulties

This article reviews the published literature that evaluated the reliability and accuracy of inferior vena cava (IVC) parameters measured by ultrasound for volume assessment, as well as those that described the potential change in these parameters induced by other factors. Several IVC parameters, including IVC diameter, phasic respiratory variation, and IVC/Aorta diameter ratio, were recommended for assessing volume status. They have been proven to be reliable, repeatable, and have good relationship with other indicators of volume status. However, the body size, respiratory status, anesthetics, and intra-thoracic and intra-abdominal pressure could affect their values. The reverse in IVC respiratory variation resulted from change in ventilation mode limits its application in the perioperative period. Ultrasound IVC measurements are reliable for volume assessment to facilitate clinical decision. The interpretation of the IVC parameters measured by ultrasound should be done by physicians aware of physiological principle and expected changes in IVC under certain circumstances.

Inaccuracy of Right Atrial Pressure Estimates Through Inferior Vena Cava Indices

The precision of echocardiography in estimating pulmonary pressures has been debated. A value of right atrial pressure (RAP) is needed for pulmonary pressure estimation, and it could be partly responsible for the estimation error. Several schemes based on the inferior vena cava (IVC) are commonly used in clinical practice and in experimental studies for RAP estimation. However, the majority lack proper validation, and thus far, no study has compared them all. In this prospective, blinded study, a comprehensive transthoracic echocardiography was performed on 200 patients referred for right heart catheterization. The IVC was measured in different views and RAP was estimated according to 6 different schemes. One hundred ninety patients were suitable for analysis. IVC measurements were significantly but poorly associated with invasive RAP. All RAP schemes showed poor accuracy compared with invasive RAP (average accuracy 34%). None of the schemes showed a clear superiority over the others. No echocardiographic or clinical variables showed a relevant impact on the estimation error. In conclusion, RAP estimation based on the IVC is highly inaccurate irrespective of the method used and should be avoided whenever possible. Whether adding estimated RAP values affects the estimation of pulmonary pressures is yet to be determined.

Baseline Diameters of Inferior Vena Cava and Abdominal Aorta Measured by Ultrasonography in Healthy Term Neonates During Early Neonatal Adaptation Period

To evaluate normative sonographic measurements of the inferior vena cava (IVC), aorta (Ao), and IVC/Ao ratio in the first 2 days of life in term neonates. We prospectively observed 200 term (more than 36 and 6/7 weeks of gestation), single, healthy neonates born in a city hospital. The exclusion criteria were congenital abnormalities, an Apgar score of less than 8, and hyperbilirubinemia requiring phototherapy. Maximum IVC (distal to the hepatic-IVC junction) and Ao (above the superior mesenteric artery) diameters were measured in the first 2 days of life in the longitudinal plane. Neonatal weight loss was calculated as a percentage lost from birth weight (BW). A total of 200 (50% born vaginally, 53% male) neonates were enrolled. Correlations between IVC and aortic diameters as a function of gestational age, method of birth, weight loss, and body surface area (BSA) were calculated using the Spearman's rank correlation coefficient. The correlation coefficients were statistically significant for the IVC (P = .017) and Ao (P = .006) abdominal diameters versus gestational age. The Ao diameter correlated with BSA (P = .0001). In neonates with weight loss less than 8% of BW, the IVC/Ao ratio remained constant at 0.62 (95% confidence interval, 0.60-0.63). Sonographic measurements of IVC and Ao maximum diameters in term neonates suggests a significant positive correlation among gestational age, BSA, and IVC and Ao diameters. The IVC/Ao ratios remain constant over 48 hours after birth in neonates with weight loss up to 8% of BW, and appear to be lower than previously reported ratios for healthy children.

Echocardiographic Inferior Vena Cava Measurement As An Alternative to Central Venous Pressure Measurement in Neonates.

To evaluate the correlation between echocardiographic inferior vena cava (IVC) measurements and central venous pressure (CVP) in neonates. Also, to evaluate the correlation between IVC measurements and gestational age (GA) and body weight (BW). Thiscross sectional analytical studywas conducted from June 2014 through June 2016 in a level III NICU. All neonates requiring intensive hemodynamic monitoring and having umbilical venous catheter (UVC) in place for clinical indications were enrolled in the study. IVC measurements were recorded by echocardiography (ECHO) and CVP was measured concomitantly in neonates having appropriate sized UVC in place. IVC measurements were evaluated and compared for any correlation with the CVP, GA and BW. Fifty neonates with median gestation of 37 wk [Q1=29.2, Q3=37.8, interquartile range (IQR)=8.6 wk] and median birth weight of 2420g (Q1=923.5, Q3=2850, IQR=1926.5g) were included in the study. A strong negative linear correlation was observed between IVC collapsibility index (IVC-CI) and CVP (r=-0.968, r2=-0.937, p 0.000). No correlation was observed between IVC-CI and GA or BW. IVC minimum and IVC maximum diameters did not correlate with CVP but correlated well with GA and BW. Echocardiographic IVC-CI measurement has a good correlation with CVP measurement in neonates. The clinical use will depend on the ability of IVC-CI to predict surrogate markers of tissue perfusion in shock.

Inferior Vena Cava Measurement with Ultrasound: What Is the Best View and Best Mode?

IntroductionIntravascular volume status is an important clinical consideration in the management of the critically ill. Point-of-care ultrasonography (POCUS) has gained popularity as a non-invasive means of intravascular volume assessment via examination of the inferior vena cava (IVC). However, there are limited data comparing different acquisition techniques for IVC measurement by POCUS. The goal of this evaluation was to determine the reliability of three IVC acquisition techniques for volume assessment: sub-xiphoid transabdominal long axis (LA), transabdominal short axis (SA), and right lateral transabdominal coronal long axis (CLA) (aka “rescue view”).MethodsVolunteers were evaluated by three experienced emergency physician sonographers (EP). Gray scale (B-mode) and motion-mode (M-mode) diameters were measured and IVC collapsibility index (IVCCI) calculated for three anatomic views (LA, SA, CLA). For each IVC measurement, we calculated descriptive statistics, intra-class correlation coefficients (ICC), and two-way univariate analyses of variance.ResultsEPs evaluated 39 volunteers, yielding 351 total US measurements. Measurements of the three views had similar means (LA 1.9 ± 0.4cm; SA 1.9 ± 0.4cm; CLA 2.0 ± 0.5cm). For B-Mode, LA had the highest ICC (0.86, 95% CI [0.76–0.92]) while CLA had the poorest ICC (0.74, 95% CI [0.56–0.85]). ICCs for all M-mode IVCCI were low. Significant interaction effects between anatomical view and EP were observed for B-mode and M-mode measurements. Post-hoc analyses revealed difficulty in consistent view acquisition between EPs.ConclusionInter-rater reliability of the IVC by EPs was highest for B-mode LA and poorest for all M-Mode IVC collapsibility indices (IVCCI). These results suggest that B-mode LA holds the most promise to deliver reliable measures of IVC diameter. Future studies may focus on validation in a clinical setting as well as comparison to a reference standard.

IVC Measurements in Critically Ill Patients with Acute Renal Failure.

Objective To determine whether the inferior vena cava (IVC) measurement by bedside ultrasound (US-IVC) predicts improvement in renal function in patients with acute kidney injury (AKI). Design Prospective observational study. Setting Medical intensive care unit. Patients 33 patients with AKI were included. Intervention US-IVC was done on admission. The patients' management was done by the primary teams, who were unaware of the US-IVC findings. Two groups of patients were identified. Group 1 included patients who were managed in concordance with their US-IVC (potential volume responders who had a positive fluid balance at 48 h after admission and potential volume nonresponders who had an even or negative fluid balance at 48 hours after admission). Group 2 included patients in whom the fluid management was discordant with their US-IVC. Measurements and Main Results At 48 hours, Group 1 patients had a greater improvement in creatinine [85% versus 31%, p = 0.0002], creatinine clearance (78 ± 93% versus 8 ± 64%, p = 0.002), and urine output (0.86 ± 0.54 versus 0.45 ± 0.36 ml/Kg/h, p = 0.03). Conclusion In critically ill patients with AKI, concurrence of fluid therapy with IVC predicted fluid management, as assessed by bedside ultrasound, was associated with improved renal function at 48 hours. This trial is registered with ClinicalTrials.gov registration number: NCT02064244.

Can Bedside Ultrasound Inferior Vena Cava Measurements Accurately Diagnose Congestive Heart Failure in the Emergency Department? A Clin-IQ

Congestive heart failure (CHF) is a major cause of morbidity and mortality. Early diagnosis of CHF in patients presenting to the emergency department (ED) with undifferentiated dyspnea would allow clinicians to begin appropriate treatment more promptly. Current guidelines recommend B-type natriuretic peptide (BNP) levels for more accurate diagnosis of CHF in dyspneic patients. Although BNP levels are relatively inexpensive, the test is not usually performed at bedside and results may take up to an hour or more. BNP may also have a "gray zone" in which the values can neither confirm nor rule out CHF. BNP has a reported sensitivity of 87% and specificity of 74% at a cutoff of 400 pg/ml. Studies investigating the sensitivity and specificity of bedside ultrasound (US) inferior vena cava (IVC) measurements for identifying CHF report a specificity of 84% to 96% and sensitivity values ranging from 37% to 93%, depending on the study. Given that US IVC measurements are performed at bedside and results are available rapidly, it is reasonable to evaluate whether US IVC measurements, taken by appropriately trained ED clinicians, alone or in combination with BNP, may increase diagnostic accuracy of congestive heart failure.