Is caval index a sufficient parameter for determining and monitoring dehydration in intoxication patients?

BACKGROUND: Cases of intoxication are increasing day by day and these patients are presenting to emergency departments. These patients are usually individuals with poor self-care, inadequate oral intake, and unable to meet their own needs, and may have significant dehydration due to the agents they have taken. The caval index (CI) is a recently used index to determine fluid requirement and response. AIMS: We aimed to evaluate the success of CI in determining and monitoring dehydration in intoxication patients. METHODS: Our study was conducted prospectively in the emergency department of a single tertiary care center. A total of ninety patients were included in the study. Caval index was calculated by measuring inspiratory and expiratory inferior vena cava diameters. Caval index measurements were repeated after 2 and 4 h. RESULTS: Patients who were hospitalized, took multiple drugs, or needed inotropic agents had significantly higher caval index levels. A further increase in caval index levels was observed on second and third caval index evaluations in patients who received inotropic agents along with fluid resuscitation. Levels of systolic blood pressure recorded at admission (0. hour) showed a significant correlation with caval index and shock index. Caval index and the shock index were highly sensitive and specific at predicting mortality. CONCLUSION: In our study, we found that CI can be used as an index to assist emergency clinicians in determining and monitoring fluid requirement in cases of intoxication presenting to the emergency department.

Processing Ultrasound Scans of the Inferior Vena Cava: Techniques and Applications.

The inferior vena cava (IVC) is the largest vein in the body. It returns deoxygenated blood to the heart from the tissues placed under the diaphragm. The size and dynamics of the IVC depend on the blood volume and right atrial pressure, which are important indicators of a patient's hydration and reflect possible pathological conditions. Ultrasound (US) assessment of the IVC is a promising technique for evaluating these conditions, because it is fast, non-invasive, inexpensive, and without side effects. However, the standard M-mode approach for measuring IVC diameter is prone to errors due to the vein movements during respiration. B-mode US produces two-dimensional images that better capture the IVC shape and size. In this review, we discuss the pros and cons of current IVC segmentation techniques for B-mode longitudinal and transverse views. We also explored several scenarios where automated IVC segmentation could improve medical diagnosis and prognosis.

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.

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.

Inferior Vena Cava Edge Tracking Echocardiography: A Promising Tool with Applications in Multiple Clinical Settings.

Ultrasound (US)-based measurements of the inferior vena cava (IVC) diameter are widely used to estimate right atrial pressure (RAP) in a variety of clinical settings. However, the correlation with invasively measured RAP along with the reproducibility of US-based IVC measurements is modest at best. In the present manuscript, we discuss the limitations of the current technique to estimate RAP through IVC US assessment and present a new promising tool developed by our research group, the automated IVC edge-to-edge tracking system, which has the potential to improve RAP assessment by transforming the current categorical classification (low, normal, high RAP) in a continuous and precise RAP estimation technique. Finally, we critically evaluate all the clinical settings in which this new tool could improve current practice.

Sonographic Estimation Rather Than Quantification of Fluid Status Using Inferior Vena Cava and Other Major Vessel Parameters in a Non-Bleeding Fluid Loss and Centralization Model.

OBJECTIVE: A well-accepted step in emergency sonography is the estimation of a fluid deficit through Inferior Vena Cava (IVC) diameter variability with known cut-offs especially in bleeding. We sought to answer, whether a non-bleeding fluid deficit can be quantified through sonographic assessment of IVC diameter variability and related aortic parameters. Sport divers were used as human hypovolemic vasoconstriction models since immersion is known to cause relevant volume depletion through vasoconstriction and induced diuresis. MATERIALS AND METHODS: Forty-one sport divers performed 342 single and repetitive dives to account for intra- and interindividual variability and were assessed for inferior Vena Cava and neighboring aortic diameters as well as their cardiac/respiratory variations. Dive-related weight loss was measured together with sonographic vessel diameter changes inferior to the right atrium. RESULTS: Highest correlation with dive-related weight loss of max. 2.9 kg per an average 47 minutes dive was found with r=0.34 for the difference of IVC maximum diameter related to minimum Aortic diameter. Single or combined parameters, as well as Collapsibility Index, showed lower or no correlations. Vascular parameters were able to explain 7.5% of the variance of fluid losses, whereas interindividual effects explained 10%. The remaining 82.5% is of mixed intraindividual counterregulatory effects. CONCLUSION: IVC diameter changes in immersion-induced hypovolemic centralization provides qualitative information on relevant fluid loss only. Confounding factors like inter and intraindividual variability prevent a sufficient correlation for useful quantification of the experienced non-bleeding fluid deficit in the clinical setting.

Caudal vena cava collapsibility index in healthy cats by ultrasonography / [Índice de colapsibilidade da veia cava caudal em gatos domésticos Saudáveis, obtido por meio de ultrassonografia]

The objective of this study was to calculate the collapsibility index (CI) in a group of 15 healthy adult mixed breed cats via right hepatic intercostal ultrasound view. The minimal and the maximal diameters of the caudal vena cava (CVC) were obtained during inspiration and expiration, respectively, then CI was calculated. The mean diameter of the CVC was 0.5cm. The mean CI was 28±3% and CI was not significantly associated with gender. As in human medicine, there is a growing need for less invasive monitoring in small animal practice. The CI enables the assessment of estimated volemia without the need for a central venous catheter. This is the first reported study investigating CI in cats.(AU)

O objetivo deste estudo foi calcular o índice de colapsabilidade (IC) em um grupo de 15 gatos adultos, saudáveis e SRD, por meio da janela ultrassonográfica hepática intercostal direita. Os diâmetros mínimo e máximo da veia cava caudal (VCC) foram obtidos durante a inspiração e a expiração, respectivamente. O IC foi calculado, posteriormente. O diâmetro médio da VCC foi de 0,5cm. O diâmetro médio do IC foi de 28±3%, e o IC não foi significativamente associado ao gênero. Como na medicina humana, há uma necessidade crescente de monitoramento menos invasivo na prática de pequenos animais. O IC possibilita a avaliação da volemia estimada sem a necessidade de um cateter venoso central. Este é o primeiro estudo relatado sobre IC em gatos domésticos.(AU)

Accuracy of right atrial pressure estimation using a multi-parameter approach derived from inferior vena cava semi-automated edge-tracking echocardiography: a pilot study in patients with cardiovascular disorders.

The echocardiographic estimation of right atrial pressure (RAP) is based on the size and inspiratory collapse of the inferior vena cava (IVC). However, this method has proven to have limits of reliability. The aim of this study is to assess feasibility and accuracy of a new semi-automated approach to estimate RAP. Standard acquired echocardiographic images were processed with a semi-automated technique. Indexes related to the collapsibility of the vessel during inspiration (Caval Index, CI) and new indexes of pulsatility, obtained considering only the stimulation due to either respiration (Respiratory Caval Index, RCI) or heartbeats (Cardiac Caval Index, CCI) were derived. Binary Tree Models (BTM) were then developed to estimate either 3 or 5 RAP classes (BTM3 and BTM5) using indexes estimated by the semi-automated technique. These BTMs were compared with two standard estimation (SE) echocardiographic methods, indicated as A and B, distinguishing among 3 and 5 RAP classes, respectively. Direct RAP measurements obtained during a right heart catheterization (RHC) were used as reference. 62 consecutive 'all-comers' patients that had a RHC were enrolled; 13 patients were excluded for technical reasons. Therefore 49 patients were included in this study (mean age 62.2 ± 15.2 years, 75.5% pulmonary hypertension, 34.7% severe left ventricular dysfunction and 51% right ventricular dysfunction). The SE methods showed poor accuracy for RAP estimation (method A: misclassification error, ME = 51%, R2 = 0.22; method B: ME = 69%, R2 = 0.26). Instead, the new semi-automated methods BTM3 and BTM5 have higher accuracy (ME = 14%, R2 = 0.47 and ME = 22%, R2 = 0.61, respectively). In conclusion, a multi-parametric approach using IVC indexes extracted by the semi-automated approach is a promising tool for a more accurate estimation of RAP.

Non-invasive Estimation of Right Atrial Pressure Using Inferior Vena Cava Echography.

The pulsatility of the inferior vena cava (IVC) reflects the volume status and central venous pressure of patients. The standard clinical indicator of IVC pulsatility is the caval index (CI), measured from ultrasound recordings. However, its estimation is not standardized and is vulnerable to artifacts, mostly because of IVC movements during respiration. Thus, we used a (recently patented) semi-automated method that tracks IVC movements and averages the CI across an entire section of the vein, which provides a more stable indication of pulsatility. This algorithm was used to estimate the CI, pulsatility indicators reflecting either respiratory or cardiac stimulation and the mean diameter of the IVC. These IVC indices, together with anthropometric information, were used as potential features to build an innovative model for the estimation of the right atrial pressure (RAP) recorded from 49 catheterized patients. An exhaustive search was carried out for the best among all possible models that could be obtained by using combinations of these features. The model with minimum estimation error (tested with a leave-one-out approach) was selected. This model estimated RAP with an error of about 3.6 ± 2.6 mm Hg (mean ± standard deviation); the error when using only operator measured variables, without software, was about 4.0 ± 2.5 mm Hg. These promising results underline the need for further study of our RAP estimation method on a larger data set.

Tracking and Monitoring Pulsatility of a Portion of Inferior Vena Cava from Ultrasound Imaging in Long Axis.

Pulsatility of the inferior vena cava (IVC) provides information on volume status in healthy subjects and in many clinical conditions. The ultrasound (US) approach to estimating the caval index (CI) is not standardized, as it is operator dependent and vulnerable to measurement errors because of different factors, including movements of the IVC and non-uniform IVC pulsatility along its longitudinal axis. We propose and test in healthy subjects an innovative automated approach, which tracks the IVC movements registered in a B-mode US video clip and estimates the pulsatility of an entire portion of the vein rather than of a single arbitrary section. Large variations in CI estimates were observed along the longitudinal axis (in the worst case, CI ranged between 15% and 60%), indicating the importance of investigating a whole portion of the vessel.

Is there an association between central venous pressure measurement and ultrasound assessment of the inferior vena cava?

INTRODUCTION: Early assessment of volume status is paramount in critically ill patients. Central venous pressure (CVP) measurement and ultrasound assessment of the inferior vena cava (IVC) are both used for volume assessment in the emergency centre. Recent data is conflicting over whether there is a correlation between CVP and ultrasound assessment of the IVC. METHODS: This was a retrospective review of an audit previously performed in the Emergency Unit of Ngwelezane Hospital in Kwazulu-Natal. The audit involved measuring inferior vena cava collapsibility index (IVC-CI) within 5 min of CVP measurement. In this retrospective study, audit data were analysed to determine if an association exists. RESULTS: Twenty-four patients were included. The median age of participants was 36 (IQR 42) years (95% CI 33-56). The median time to ultrasound was 18.6 (52.5) h (95% CI 7.5-36.2). The mean CVP was 13.7 ±â€¯7.7 cm H2O and mean IVC-CI was 39.4 ±â€¯17.8%. Based on a Pearson correlation test, there was a weak negative correlation between CVP and IVC-CI, which was not statistically significant (r = -0.05, n = 24, p = 0.81, 95% CI -0.5 to 0.4) for all participants. However, among females there was a moderate negative correlation between CVP and IVC-CI, which was not statistically significant (r = -0.43, n = 7, p = 0.34, 95% CI -0.9 to 0.5), while among males there was a weak positive correlation, which was not statistically significant (r = 0.16, n = 17, p = 0.53, 95% CI -0.3 to 0.6). DISCUSSION: There is no significant correlation between CVP and IVC-CI. Further validation research is required to support our preliminary findings of no significant correlation between CVP measurement and ultrasound assessment of the IVC. CVP and IVC ultrasound should be used as clinical adjuncts, and not as stand-alone measures of volume assessment.

Inferior vena cava assessment can predict contrast-induced nephropathy in patients undergoing cardiac catheterization: A single-center prospective study.

BACKGROUND: Contrast-induced nephropathy (CIN) following cardiac catheterization remains a considerable clinic challenge. Volume status is very important in the development of CIN. It can be assessed noninvasively by measuring inferior vena cava (IVC) diameters. The aim of this study was to assess whether IVC can be used for prediction of CIN in patient undergoing cardiac catheterization. METHODS: A total of 269 patients undergoing cardiac catheterization were prospectively enrolled in this study. IVC inspiratory and expiratory diameters were measured by transthoracic echocardiography. Caval index was calculated as the percentage decrease in the IVC diameter during respiration. CIN was defined as a ≥0.5 mg/dL and/or a ≥25% increase in serum creatinine within 72 hour post-procedure. RESULTS: Contrast-induced nephropathy developed in 46 (17.1%) patients after cardiac catheterization. Caval index was significantly higher in patients with CIN than in patients without CIN (47% [40-64] vs 35% [26-50], P < 0.001). In addition, the used contrast volume (145 [90-217] vs 70 [60-100], P < 0.001) and the frequency of percutaneous coronary intervention (50% vs 17.9%, P < 0.001) were significantly higher in patients with CIN than in patients without CIN. In receiver operating characteristic (ROC) curve analysis, caval index ≥ 41% predicted CIN with a specificity of 69% and sensitivity of 72%. Multivariate analysis indicated that caval index ≥ 41% was an independent predictor of post-procedural CIN development (OR: 3.367, 95% CI: 1.574-7.203, P = 0.002). CONCLUSIONS: Caval index, a simple and noninvasive echocardiographic marker, is an independent predictor of post-procedural CIN development in patients undergoing cardiac catheterization.

The learning curve of sonographic inferior vena cava evaluation by novice medical students: the Pavia experience.

PURPOSE: The sonographic evaluation of inferior vena cava diameters and its collapsibility-that is also defined as the caval index-has become a popular way to easily obtain a noninvasive estimate of central venous pressure. This is generally considered an easy sonographic task to perform, and according to the American College of Emergency Physicians (ACEP) Guidelines 25 repetitions of this procedure should be sufficient to reach proficiency. However, little is known about the learning process for this sonographic technique. Therefore, we designed this study to investigate the learning curve of inferior vena cava evaluation. METHODS: We enrolled a sample of ten ultrasound-naïve medical students who received a preliminary training provided by two Junior Emergency Medicine Residents. Following training, each student performed the sonographic task on 25 different patients who were hospitalized in the internal medicine ward. The students' performance was compared with the results obtained by a consultant in internal medicine with extensive experience in point-of-care ultrasound, who repeated the procedure on the same patients (gold standard). In detail, we evaluated the time to complete the task, the quality of the obtained images, and the ability to visually estimate and measure the caval index. RESULTS: Although most students (9/10) reached the pre-defined level of competence, their overall performance was inferior to the one achieved by the gold standard, with little improvement over time. However, repetition was associated with progressive shortening of the time needed to achieve readable images. CONCLUSIONS: Overall, these findings suggest that, although allowing to obtain a pre-defined competence, 25 repetitions are not enough to reach a good level of proficiency for this technique, that needs a longer training to be achieved.

The PCQP Score for Volume Status of Acutely Ill Patients: Integrating Vascular Pedicle Width, Caval Index, Respiratory Variability of the QRS Complex and R Wave Amplitude.

INTRODUCTION: Techniques for measuring volume status of critically ill patients include invasive, less invasive, or noninvasive ones. The present study aims to assess the accuracy of noninvasive techniques for measuring volume status of critically ill patients. PATIENTS AND METHODS: A total of 111 critically ill patients admitted to the emergency department and undergoing central venous catheterization were included in the study. Five parameters were measured including vascular pedicle width (VPW), diameter of inferior vena cava, caval index, respiratory changes in QRS, and P wave amplitude. Patients with risk factors which could decrease the accuracy of central venous pressure (CVP) value were excluded from study. We compared these parameters with static CVP parameter. Finally, based on the afore-mentioned parameters, PCQP role in criteria was designed. RESULTS: In detecting loss of circulating blood volume, area under the curve of VPW was 0.92 (90%, confidence interval [CI]: 0.85-0.99), diameter of inferior vena cava was 0.82 (90%, CI: 0.72-0.91), caval index was 0.9 (90%, CI: 0.82-0.98), and changes in QRS and P waves were 0.88 (95%, CI: 0.81-0.95) and 0.73 (95%, CI: 0.63-0.82), respectively. PCQP role in criteria was designed according to these parameters, and at its best cutoff point (score 6), VPW had a sensitivity of 97.4% (95%, CI: 84.57-99.99) and specificity of 83.6% (95%, CI: 72.65-90.86) for the detection of loss of circulating blood volume (<8 cmH2O). CONCLUSION: PCQP score could be a reliable and noninvasive technique for the assessment of volume status in critically ill patients.

Vena Cava Responsiveness to Controlled Isovolumetric Respiratory Efforts.

OBJECTIVES: Respirophasic variation of inferior vena cava (IVC) size is affected by large variability with spontaneous breathing. This study aims at characterizing the dependence of IVC size on controlled changes in intrathoracic pressure. METHODS: Ten healthy subjects, in supine position, performed controlled isovolumetric respiratory efforts at functional residual capacity, attaining positive (5, 10, and 15 mmHg) and negative (-5, -10, and -15 mmHg) alveolar pressure levels. The isovolumetric constraint implies that equivalent changes are exhibited by alveolar and intrathoracic pressures during respiratory tasks. RESULTS: The IVC cross-sectional area equal to 2.88 ± 0.43 cm2 at baseline (alveolar pressure = 0 mmHg) was progressively decreased by both expiratory and inspiratory efforts of increasing strength, with diaphragmatic efforts producing larger effects than thoracic ones: -55 ± 15% decrease, at +15 mmHg of alveolar pressure (P < .01), -80 ± 33 ± 12% at -15 mmHg diaphragmatic (P < .01), -33 ± 12% at -15 mmHg thoracic. Significant IVC changes in size (P < .01) and pulsatility (P < .05), along with non significant reduction in the response to respiratory efforts, were also observed during the first 30 minutes of supine rest, detecting an increase in vascular filling, and taking place after switching from the standing to the supine position. CONCLUSIONS: This study quantified the dependence of the IVC cross-sectional area on controlled intrathoracic pressure changes and evidenced the stronger influence of diaphragmatic over thoracic activity. Individual variability in thoracic/diaphragmatic respiratory pattern should be considered in the interpretation of the respirophasic modulations of IVC size.

Ultrasonographic caval indices do not significantly contribute to predicting fluid responsiveness immediately after coronary artery bypass grafting when compared to passive leg raising.

BACKGROUND: Appropriate fluid management is one of the most important elements of early goal-directed therapy after cardiothoracic surgery. Reliable determination of fluid responsivenss remains the fundamental issue in volume therapy. The purpose of the study was to assess the usefulness of dynamic IVC-derived parameters (collapsibility index, distensibility index) in comparison to passive leg raising, in postoperative fluid management in mechanically ventilated patients with left ventricular ejection fraction ≥ 30 %, immediately after elective coronary artery bypass grafting. METHODS: Prospective observational case series study including 35 patients with LVEF ≥ 30 %, undergoingelective coronary artery bypass grafting was conducted. Transthoracic echocardiography, passive leg raising and intravenous administration of saline were performed in all study subjects. Dynamic parameters derived from ultrasonographic assessment of the IVC diameter (collapsibility index-CI and distensibility index-DI), cardiac output RESULTS: There were 24 (68.57 %) responders in the study population. There were no statistical differences between the groups in relation to: clinical parameters, pre- and postoperative LVEF, fluid balance and CVP. Change in cardiac output after passive leg raising correlated significantly with that after the volume expansion (p=0.000, r=0.822). Dynamic IVC derivatives were slightly higher in fluid responders, however this trend did not reach statistical significance. None of the caval indices correlated with fluid responsiveness. CONCLUSION: Dynamic IVC-derived parameters do not predict fluid responsiveness in mechanically ventilated patients with preserved ejection fraction immediately after elective coronary artery bypass grafting. Passive leg raising is not inferior to volume expansion in differentiating between fluid responders and nonresponders. Immediate fluid challenge after CABG is safe and well tolerated.

Sonographic inferior vena cava measurements to assess hydration status in college football players during preseason camp.

OBJECTIVES: The purpose of this study was to determine whether sonographic measurement of the inferior vena cava (IVC) in college football players during preseason camp is a reliable way to detect and monitor dehydration. Our primary hypothesis was that IVC diameter measurements, the postpractice caval index, and expiratory diameter were significantly related to percent weight loss after a preseason football practice. METHODS: A prospective cohort sample of Division I intercollegiate football players in preseason training camp was recruited before practice. All football players on the active roster who were at least 18 years of age were eligible to participate in the study. Sonographic IVC measurements were obtained in the long axis using either the subcostal or subxiphoid approach during inspiration and expiration both before and after an approximately 3-hour practice with moderate to high levels of exertion at high ambient temperatures. Player weights were recorded in the locker room before and after practice. RESULTS: A total of 27 prepractice and postpractice sonographic measurements were obtained. The postpractice expiratory IVC diameter was significantly related to percent weight loss after practice (R(2) = 0.153; P = .042), with the IVC diameter being significantly inversely correlated with percent weight loss; the regression coefficient was -1.07 (95% confidence interval, -2.09 to -0.04). There was no statistically significant relationship between percent weight loss and the postpractice caval index; the regression coefficient was 0.245 (95% confidence interval, -0.10 to 0.59; R(2) = 0.078; P = .16). CONCLUSIONS: The postpractice expiratory IVC diameter was significantly related to percent weight loss after practice, whereas the caval index was not found to correlate with weight loss.

Correlation of caval index, inferior vena cava diameter, and central venous pressure in shock patients in the emergency room.

OBJECTIVES: This study aims to determine the correlation of the caval index, inferior vena cava (IVC) diameter, and central venous pressure (CVP) in patients with shock in the emergency room. MATERIALS AND METHODS: This is a prospective double-blind observational study conducted in the emergency room of a tertiary care center. All patients who presented with shock and had a central venous catheter insertion performed were enrolled. The caval index was calculated as a relative decrease in the IVC diameter during the normal respiratory cycle. The correlation of CVP and the caval index were calculated by Pearson's product-moment correlation coefficient. RESULTS: Among the 30 patients enrolled, the median age was 59.90±21.81 years and 17 (56.7%) patients were men. The summary statistics that were generated for the participants' characteristics were divided into CVP <10 cm H2O, 10-15 cm H2O, and >15 cm H2O. The correlation of the CVP measurement with the ultrasound IVC caval index was r=-0.721 (P=0.000) by two-dimensional mode ultrasound and r=-0.647 (P=0.001) by M-mode. The correlations of CVP with the end-expiratory IVC diameter were r=0.551 (P=0.002) by two-dimensional mode ultrasound and r=0.492 (P=0.008) by M-mode. The sensitivity and specificity of the caval index were calculated to predict the CVP. The results showed that the cut-off points of the caval index were 30, 20, and 10 at CVP levels <10 cm H2O, 10-15 cm H2O, and >15 cm H2O, respectively. CONCLUSION: The caval index calculated from the IVC diameter measured by bedside ultrasound in the emergency room has a good correlation with CVP.