Vena cava diameter measurement for estimation of dry weight in haemodialysis patients

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.

Use of Point-of-Care Ultrasound for Evaluation of Extravascular and Intravascular Fluid Status in Pediatric Patients Maintained on Chronic Hemodialysis

AIMS

Traditional methods that use clinical parameters to determine dry weight in hemodialysis patients are inaccurate. This study aimed to compare clinical assessment of fluid status to sonographic parameters of fluid status in pediatric patients undergoing chronic hemodialysis.

METHODS

In a prospective observational study, pediatric patients maintained on chronic hemodialysis (ages 2.3-20 years) were evaluated clinically and sonographically before and after dialysis at 6 consecutive sessions. Sonographic parameters examined were number of lung B-lines as a measure of extravascular volume and inferior vena cava (IVC)/aorta ratio as a measure of intravascular volume. Clinical assessment of fluid status was compared to sonographic assessment.

RESULTS

Twelve patients were evaluated during 72 dialysis sessions. Sonographic parameters were significantly lower post-dialysis than pre-dialysis (B-lines number 4.5 ± 5 vs. 7.69 ± 7.46, p < 0.0001; IVC/aorta ratio 0.9 ± 0.2 vs. 1.1 ± 0.2, p < 0.0001, respectively). Ultrafiltration volume correlated with change in B-lines number during dialysis (r = 0.39, p < 0.01). Percent of blood volume drop correlated with post-dialysis IVC/aorta ratio (r = 0.48, p < 0.001). A higher percent of symptomatic episodes occurred with post-dialysis IVC/aorta ratio <0.8 versus ≥0.8 (39.1 vs. 15.2%, p = 0.036). Four patients were hypertensive, a clinical parameter implying fluid overload, in only one sonographic evaluation indicated fluid overload. Eight patients were clinically determined to be euvolemic, in three of them sonographic evaluation discovered covert fluids.

CONCLUSION

Bedside ultrasound is a single modality that can be used to assess both extravascular and intravascular fluid status. It may contribute to clinical decisions differentiating fluid-related versus fluid-unrelated hypertension and identifying patients with covert fluids.

Bioimpedance analysis is not superior to clinical assessment in determining hydration status: A prospective randomized-controlled trial in a Western dialysis population

INTRODUCTION

Fluid management is an important goal of dialysis treatment. The accurate assessment of fluid status is still a challenge for clinical nephrologists. Bioimpedance analysis (BIA) has been proposed as an objective tool to assess hydration.

METHODS

This was a prospective randomized controlled study to compare hydration status measured by clinical assessment compared to BIA using a body composition monitor (BCM). The primary outcome was defined as the decline of cardiac biomarker N-terminal pro brain natriuretic peptide (NT-proBNP) from baseline to the end of the study.

FINDINGS

About 281 chronic hemodialysis patients were assessed for eligibility, and 132 patients provided written informed consent to participate (65 BIA group, 67 clinical group). Predialytic NT-proBNP, and decline of NT-proBNP were similar in both groups. The amount of overhydration (2.18 ± 2.11 L vs. 1.29 ± 1.97 L; p 0.016) and the number of patients with severe overhydration (46.0% vs. 30.6%, p = 0.04) were significantly higher in the BIA group at the end of the study. Fluid accumulation in the interdialytic period was significantly lower in the clinical group (p = 0.013). Adverse events occurred more often in the BIA group (p = 0.032). The cumulative number of hypovolemic events was significantly higher in the BIA group (p = 0.002).

DISCUSSION

Fluid management by BIA does not lead to a better cardiac outcome (appraised by surrogate markers) than fluid management by careful clinical assessment. Adapting the dry weight according to BIA results increases the risk of adverse events, especially hypovolemic episodes. Careful clinical fluid assessment is important for optimal care of chronic hemodialysis patients.

Association of inferior vena cava diameter ratio measured on computed tomography scans with the outcome of patients with septic shock

The collapsibility and diameter of the inferior vena cava (IVC) are known to predict the volume state in critically ill patients. However, no study has examined the prognostic value of the IVC diameter ratio measured on computed tomography (CT) in patients with septic shock. A retrospective observational study was conducted on adult septic shock patients visiting the emergency department at a university hospital in Korea. The IVC diameter ratio was calculated by dividing the maximal transverse and anteroposterior diameters. Multivariable logistic regression analysis was conducted to investigate whether the IVC diameter ratio predicted in-hospital mortality. The area under the curve (AUC) was calculated, and the sensitivity, specificity, positive predictive value, and negative predictive value with the cut-off values were computed. A total of 423 adult septic shock patients were included, and the in-hospital mortality rate was 17%. The median IVC diameter ratio in non-survivors was significantly greater than in survivors (1.56 cm vs 1.4 cm, P = .004). The IVC diameter ratio was found to be significantly associated with in-hospital mortality on multivariate logistic regression analysis after adjustment for confounding variables (odds ratio = 1.48, confidence interval: 1.097-1.998, P = 0.01). The AUC for IVC diameter ratio was 0.607. A cut-off IVC diameter ratio of ≥1.31 cm had 75% sensitivity and 42% specificity for predicting in-hospital mortality. The IVC diameter ratio measured on CT may to be helpful in predicting the prognosis of septic shock patients. However, due to its low diagnostic performance and sensitivity, further research is warranted.

Venous and Arterial Responses to Partial Gravity

Introduction: Chronic exposure to the weightlessness-induced cephalad fluid shift is hypothesized to be a primary contributor to the development of spaceflight-associated neuro-ocular syndrome (SANS) and may be associated with an increased risk of venous thrombosis in the jugular vein. This study characterized the relationship between gravitational level (G_z-level) and acute vascular changes.

Methods: Internal jugular vein (IJV) cross-sectional area, inferior vena cava (IVC) diameter, and common carotid artery (CCA) flow were measured using ultrasound in nine subjects (5F, 4M) while seated when exposed to 1.00-G_z, 0.75-G_z, 0.50-G_z, and 0.25-G_z during parabolic flight and while supine before flight (0-G analog). Additionally, IJV flow patterns were characterized.

Results: IJV cross-sectional area progressively increased from 12 (95% CI: 9–16) mm² during 1.00-G_z seated to 24 (13–35), 34 (21–46), 68 (40–97), and 103 (75–131) mm² during 0.75-G_z, 0.50-G_z, and 0.25-G_z seated and 1.00-G_z supine, respectively. Also, IJV flow pattern shifted from the continuous forward flow observed during 1.00-G_z and 0.75-G_z seated to pulsatile flow during 0.50-G_z seated, 0.25-G_z seated, and 1.00-G_z supine. In contrast, we were unable to detect differences in IVC diameter measured during 1.00-G seated and any level of partial gravity or during 1.00-G_z supine. CCA blood flow during 1.00-G seated was significantly less than 0.75-G_z and 1.00-G_z supine but differences were not detected at partial gravity levels 0.50-G_z and 0.25-G_z.

Conclusions: Acute exposure to decreasing G_z-levels is associated with an expansion of the IJV and flow patterns that become similar to those observed in supine subjects and in astronauts during spaceflight. These data suggest that G_z-levels greater than 0.50-G_z may be required to reduce the weightlessness-induced headward fluid shift that may contribute to the risks of SANS and venous thrombosis during spaceflight.

Assessment of Hydration Status in Peritoneal Dialysis Patients: Validity, Prognostic Value, Strengths, and Limitations of Available Techniques

BACKGROUND

The majority of patients undergoing peritoneal dialysis (PD) suffer from volume overload and this overhydration is associated with increased mortality. Thus, optimal assessment of volume status in PD is an issue of paramount importance. Patient symptoms and physical signs are often unreliable indexes of true hydration status.

SUMMARY

Over the past decades, a quest for a valid, reproducible, and easily applicable technique to assess hydration status is taking place. Among existing techniques, inferior vena cava diameter measurements with echocardiography and natriuretic peptides such as brain natriuretic peptide and N-terminal pro-B-type natriuretic peptide were not extensively examined in PD populations; while having certain advantages, their interpretation are complicated by the underlying cardiac status and are not widely available. Bioelectrical impedance analysis (BIA) techniques are the most studied tool assessing volume overload in PD. Volume overload assessed with BIA has been associated with technique failure and increased mortality in observational studies, but the results of randomized trials on the value of BIA-based strategies to improve volume-related outcomes are contradictory. Lung ultrasound (US) is a recent technique with the ability to identify volume excess in the critical lung area. Preliminary evidence in PD showed that B-lines from lung US correlate with echocardiographic parameters but not with BIA measurements. This review presents the methods currently used to assess fluid status in PD patients and discusses existing data on their validity, applicability, limitations, and associations with intermediate and hard outcomes in this population. Key Message: No method has proved its value as an intervening tool affecting cardiovascular events, technique, and overall survival in PD patients. As BIA and lung US estimate fluid overload in different compartments of the body, they can be complementary tools for volume status assessment.

The utility and limitation of inferior vena cava diameter as a dry weight marker

BACKGROUND

IVC diameter on expiration (IVCdexp) is measured by echocardiography routinely. It is used to estimate volume status and designated as a definitive marker for determining dry weight (DW) in patients undergoing hemodialysis (HD).

METHODS

A cross-sectional study. Outpatients (n = 107), and inpatients (n = 35) undergoing HD were enrolled. IVCdexp was measured on non-dialysis days in outpatients and dialysis days before and after the dialysis session in inpatients. In outpatients, the relationship of IVCdexp with echocardiography findings and clinical characteristics was analyzed. IVCdexp was compared with the other DW markers as a predictive factor for intradialytic hypotension. In inpatients, IVCdexp was analyzed by dividing inpatients with or without fluid in extravascular space.

RESULTS

IVCdexp ranged from 5.4 to 16.9 mm in outpatients who had optimal DW. IVCdexp could reflect on volume status, but not predictive for intradialytic hypotension and not suggestive of fluid in extravascular space.

CONCLUSIONS

IVCdexp was a rough marker to estimate volume status and only useful in suggesting apparent hypervolemia or hypovolemia. We should know that the IVCdexp value is affected by a lotof factors and not a definitive marker for estimating practical DW. J. Med. Invest. 66 : 172-177, February, 2019.

Respiratory variations of inferior vena cava fail to predict fluid responsiveness in mechanically ventilated patients with isolated left ventricular dysfunction

Background

Respiratory variation of inferior vena cava is problematic in predicting fluid responsiveness in patients with right ventricular dysfunction. However, its effectiveness in patients with isolated left ventricular systolic dysfunction (ILVD) has not been reported. We aimed to explore whether inferior vena cava diameter distensibility index (dIVC) can predict fluid responsiveness in mechanically ventilated ILVD patients.

Methods

Patients admitted to the intensive care unit who were on controlled mechanical ventilation and in need of a fluid responsiveness assessment were screened for enrolment. Several echocardiographic parameters, including dIVC, tricuspid annular plane systolic excursion (TAPSE), left ventricular ejection fraction (LVEF), and LV outflow tract velocity–time integral (VTI) before and after passive leg raising (PLR) were collected. Patients with LV systolic dysfunction only (TAPSE ≥ 16 mm, LVEF < 50%) were considered to have isolated left ventricular systolic dysfunction (ILVD).

Results

One hundred and twenty-nine subjects were enrolled in this study, among them, 28 were labelled ILVD patients, and the remaining 101 were patients with normal LV function (NLVF). The value of dIVC in ILVD patients was as high as that in NLVF patients, (20% vs. 16%, p = 0.211). The ILVD group contained a much lower proportion of PLR responders than NLVF patients did (17.9% vs. 53.2%, p < 0.001). No correlation was detected between dIVC and ΔVTI in ILVD patients (r = 0.196, p = 0.309). dIVC was correlated with ΔVTI in NLVF patients (r = 0.722, p < 0.001), and the correlation was strengthened compared with that derived from all patients (p = 0.020). A receiver-operating characteristic (ROC) analysis showed that the area-under-the-curve (AUC) of dIVC for determining fluid responsiveness from ILVD patients was not statistically significant (p = 0.251). In NLVF patients, ROC analysis revealed an AUC of 0.918 (95% CI 0.858–0.978; p < 0.001), which was higher than the AUC derived from all patients (p = 0.033). Patients with LVEF below 40% had a lower ΔVTI and fewer PLR responders than those with LVEF 40–50% and LVEF above 50% (p < 0.001).

Conclusion

dIVC should be used with caution when critically ill patients on controlled mechanical ventilation display normal right ventricular function in combination with abnormal left ventricular systolic function.

Steady Flow in a Patient-Averaged Inferior Vena Cava-Part I: Particle Image Velocimetry Measurements at Rest and Exercise Conditions

PURPOSE

Although many previous computational fluid dynamics (CFD) studies have investigated the hemodynamics in the inferior vena cava (IVC), few studies have compared computational predictions to experimental data, and only qualitative comparisons have been made. Herein, we provide particle image velocimetry (PIV) measurements of flow in a patient-averaged IVC geometry under idealized conditions typical of those used in the preclinical evaluation of IVC filters.

METHODS

Measurements are acquired under rest and exercise flow rate conditions in an optically transparent model fabricated using 3D printing. To ensure that boundary conditions are well-defined and to make follow-on CFD validation studies more convenient, fully-developed flow is provided at the inlets (i.e., the iliac veins) by extending them with straight rigid tubing longer than the estimated entrance lengths. Velocity measurements are then obtained at the downstream end of the tubing to confirm Poiseuille inflow boundary conditions.

RESULTS

Measurements in the infrarenal IVC reveal that flow profiles are blunter in the sagittal plane (minor axis) than in the coronal plane (major axis). Peak in-plane velocity magnitudes are 4.9 cm/s and 27 cm/s under the rest and exercise conditions, respectively. Flow profiles are less parabolic and exhibit more inflection points at the higher flow rate. Bimodal velocity peaks are also observed in the sagittal plane at the elevated flow condition.

CONCLUSIONS

The IVC geometry, boundary conditions, and infrarenal velocity measurements are provided for download on a free and publicly accessible repository at https://doi.org/10.6084/m9.figshare.7198703 . These data will facilitate future CFD validation studies of idealized, in vitro IVC hemodynamics and of similar laminar flows in vascular geometries.

Establishment of reference values of the caudal vena cava by fast-ultrasonography through different views in healthy dogs

BACKGROUND

Clinical assessment of intravascular volume status is challenging. In humans, ultrasonographic assessment of the inferior vena cava diameter, directly or as a ratio to the aortic diameter is used to estimate intravascular volume status.

OBJECTIVES

To ultrasonographically obtain reference values (RV) for caudal vena cava diameter (CVCD ), area (CVCa ) and aortic ratios using 3 views in awake healthy dogs.

ANIMALS

One hundred and twenty-six healthy adult dogs from clients, students, faculty, or staff.

METHODS

Prospective, multicenter, observational study. Two observer pairs evaluated CVCD by a longitudinal subxiphoid view (SV), a transverse 11th-13th right hepatic intercostal view (HV), and a longitudinal right paralumbar view (PV). Inter-rater agreements were estimated using concordance correlation coefficients (CCC). For body weight (BW)-dependent variables, RVs were calculated using allometric scaling for variables with a CCC ≥ 0.7.

RESULTS

The CCC was ≤0.43 for the CVC/aorta ratio at the PV and ≤0.43 in both inspiration and expiration for CVC at the SV. The RVs using allometric scaling for CVCa at the HV for inspiration, expiration, and for CVCD at the PV were 6.16 × BW0.762 , 7.24 × BW0.787 , 2.79 × BW0.390 , respectively.

CONCLUSIONS AND CLINICAL IMPORTANCE

The CVCD , measured at the HV and PV in healthy awake dogs of various breeds has good inter-rater agreement suggesting these sites are reliable in measuring CVCD . Established RVs for CVCD for these sites need further comparison to results obtained in hypovolemic and hypervolemic dogs to determine their usefulness to evaluate volume status in dogs.

The Impact of Equations on Calculation of Lean Body Mass by Bioelectrical Impedance Analysis in RDT Patients

Several equations are available to derive lean body mass (LBM) from bioelectrical impedance analysis (BIA). The purpose of this study was to investigate in dialysis patients the impact of the equation used on the outcome of LBM assessment. To avoid dyshydration as a confounder, vena cava diameter measurement was used to assess normohydration in the 21 patients studied. Five equations were compared.

In a previously published study to assess total body water using antipyrine as a gold standard, Deurenberg's formula was advocated to be used in the estimation of LBM by BIA. Therefore, this formula was used as a basis for comparison with the other four equations.

One equation gave results comparable to those obtained by Deurenberg's formula. Despite high correlations and agreement according to Bland and Altman analysis, the other three equations showed a significant difference with Deurenberg-derived LBM. Thus, the equation used has a major impact on the outcome of LBM estimations. (Int J Artif Organs 2000; 23: 168–72)

Central venous pressure and ultrasonographic measurement correlation and their associations with intradialytic adverse events in hospitalized patients: A prospective observational study

PURPOSE

To investigate correlation of central venous pressure (CVP) with ultrasonographic measurement of central veins, along with association between these variables and occurrence of intradialytic adverse events in hospitalized patients.

MATERIALS AND METHODS

Patients requiring hemodialysis via dialysis catheter were prospectively enrolled. CVP measurements through catheter, internal jugular vein aspect ratio, subclavian vein collapsibility, inferior vena cava (IVC) maximal diameter, and IVC collapsibility were recorded before and after hemodialysis. Predictive accuracy of ultrasonographic measurements in discriminating high versus low CVP and their association with intradialytic adverse events were evaluated. Area under receiver operating characteristic curves (AUCs) were calculated.

RESULTS

Fifty-nine patients were enrolled. Median (interquartile range) pre- and post-dialysis CVPs were 8 (4-13)mmHg and 6 (3-10)mmHg, respectively (P<0.01). In pre-dialysis, IVC collapsibility had the highest AUC (0.79, P<0.01) to predict CVP >8mmHg. In post-dialysis, IVC maximal diameter had the highest AUC (0.86, P<0.01) to predict CVP ≤4mmHg. Fifteen patients (25%) had adverse events. Neither pre-dialytic CVP nor ultrasonographic variables were associated with occurrence of adverse events.

CONCLUSIONS

Highest accuracy in predicting low and high CVP was observed with ultrasonographic assessment of IVC diameter and collapsibility. Adverse events were not predicted by pre-dialytic CVP or ultrasonographic measurements.

Focused Real-Time Ultrasonography for Nephrologists

We propose that renal consults are enhanced by incorporating a nephrology-focused ultrasound protocol including ultrasound evaluation of cardiac contractility, the presence or absence of pericardial effusion, inferior vena cava size and collapsibility to guide volume management, bladder volume to assess for obstruction or retention, and kidney size and structure to potentially gauge chronicity of renal disease or identify other structural abnormalities. The benefits of immediate and ongoing assessment of cardiac function and intravascular volume status (prerenal), possible urinary obstruction or retention (postrenal), and potential etiologies of acute kidney injury or chronic kidney disease far outweigh the limitations of bedside ultrasonography performed by nephrologists. The alternative is reliance on formal ultrasonography, which creates a disconnect between those who order, perform, and interpret studies, creates delays between when clinical questions are asked and answered, and may increase expense. Ultrasound-enhanced physical examination provides immediate information about our patients, which frequently alters our assessments and management plans.

Capillary Leak Syndrome Following Snakebite Envenomation

Capillary leak syndrome is a unique complication that follows Russell's viper envenomation. This syndrome has a very high fatality rate and is characterized by parotid swelling, chemosis, periorbital edema, hypotension, albuminuria, hypoalbuminemia, and hemoconcentration. This syndrome is frequently recognized from the southern parts of India, especially from the state of Kerala. It has been postulated that a vascular apoptosis inducing component of Russell's viper venom that is not neutralized by the commercially available anti-snake venom (ASV) is responsible for this complication as it occurs even after adequate doses of ASV administration in most cases. Acute kidney injury often requiring dialysis is invariably present in all patients because of reduced renal perfusion and ischemic acute tubular necrosis as a result of hypotension. Management mainly involves aggressive fluid resuscitation to maintain adequate tissue perfusion. There are no other proven effective treatment modalities, except a few reports of successful treatment with plasmapheresis. Methylprednisolone pulse therapy, terbutaline, aminophylline, and intravenous immunoglobulin are other treatment modalities tried.

Comparison of multiple fluid status assessment methods in patients on chronic hemodialysis

PURPOSE

Control of hydration status is an important constituent of adequate and efficient hemodialysis (HD) treatment. Nevertheless, there are no precise clinical indices for early recognition of small changes in fluid status of patients undergoing chronic hemodialysis therapy. This study aimed to evaluate and compare the widely used and reliable method of indexed inferior vena cava diameter (IVCDi) with established and more recently available techniques (bioelectrical impedance analysis [BIA], continuous blood volume monitoring [Crit-line], and the B-line score [BLS] with lung ultrasonography) for estimating the hydration status of patients on HD.

METHODS

Fifty-three patients undergoing chronic HD thrice weekly were included in the study. Evaluation of hydration status methods (IVCDi, BLS, BIA, and Crit-line) was performed thrice weekly before and after HD. Receiver operating characteristic curve analysis was performed to evaluate the discriminative power of (methods) the BLS, BIA, and Crit-line for predicting over- and underhydration of patients, as determined by the reference method, IVCDi.

RESULTS

BLS showed the most promising results in predicting overhydration, as determined by IVCDi, compared with BIA and Crit-line and presented a sensitivity of 77% and specificity of 74%. The accuracy of the BLS was higher than that of BIA (0.81 vs. 0.71, p = 0.032) and Crit-line (0.61, p = 0.001). BLS also showed more promising results in predicting underhydration, as determined by IVCDi, than BIA and Crit-line and presented a sensitivity of 78% and a specificity of 73%. The accuracy of the BLS was higher than that of BIA (0.83 vs. 0.76, p = 0.035) and Crit-line (0.50, p < 0.001).

CONCLUSIONS

The BLS is a useful and easily performed technique that has recently become available for accurate evaluation of dry weight and fluid status in patients with end-stage renal disease undergoing chronic HD. This method might help recognize asymptomatic lung congestion in these patients.

Assessment of inferior vena cava diameter by echocardiography in normal Indian population: A prospective observational study

BACKGROUND

The assessment of the IVC diameter is self explanatory for evaluation of the individuals' volume status. Studies regarding IVC diameter estimation in normal individuals are scarce.

AIM

The present study aimed to define normal criteria of size and dynamics of the inferior vena cava (IVC) by M-mode echocardiography in normal individuals.

METHODS

This was a prospective, single-center, observational study carried out at Sri Jayadeva Institute of Cardiovascular Sciences and Research between December 2011 and April 2014. A total of 4126 consecutive individuals were enrolled. Normal IVC diameter was measured both during inspiration and expiration by M-mode echocardiography in subcostal view.

RESULTS

The IVC diameter varied from 0.46 to 2.26cm in the study individuals. The IVC diameter ranged from 0.97 to 2.26cm during expiration and from 0.46 to 1.54cm during inspiration. A strong correlation was observed between IVC diameter and height, weight and BMI of the individuals, calculated using Pearson correlation. The correlation coefficients for expiratory and inspiratory IVC diameters as a function of BMI were 0.686 and 0.7, respectively.

CONCLUSIONS

Our findings corroborate the correlations between height, weight and BMI with IVC diameter. Future studies could be focused to bring about a steadfast formula for calculating IVC diameter based on demographic parameters of an individual.

Agreement between inferior vena cava diameter measurements by subxiphoid versus transhepatic views

Context:

Correcting hypovolemia is extremely important. Central venous pressure measurement is often done to assess volume status. Measurement of inferior vena cava (IVC) is conventionally done in the subcostal view using ultrasonography. It may not be possible to obtain this view in all patients.

Aims:

We therefore evaluated the limits of agreement between the IVC diameter measurement and variation in subcostal and that by the lateral transhepatic view.

Settings and Design:

Prospective study in a tertiary care referral hospital intensive care unit.

Subjects and Methods:

After Institutional Ethics Committee approval and informed consent, we obtained 175 paired measurements of the IVC diameter and variation in both the views in adult mechanically ventilated patients. The measurements were carried out by experienced researchers. We then obtained the limits of agreement for minimum, maximum diameter, percentage variation of IVC in relation to respiration.

Statistical Analysis Used:

Bland–Altman's limits of agreement to get precision and bias.

Results:

The limits of agreement were wide for minimum and maximum IVC diameter with variation of as much as 4 mm in both directions. However, the limits of agreement were much narrower when the percentage variation in relation to respiration was plotted on the Bland–Altman plot.

Conclusions:

We conclude that when it is not possible to obtain the subcostal view, it is possible to use the lateral transhepatic view. However, using the percentage variation in IVC size is likely to be more reliable than the absolute diameter alone. It is possible to use both views interchangeably.

Clinical Significance of the Edema Index in Incident Peritoneal Dialysis Patients

Background

Proper monitoring for volume overload is important to improve prognosis in peritoneal dialysis (PD) patients. The association between volume status and residual renal function (RRF) remains an unresolved issue. The aim of the present study was to evaluate the association between the edema index and survival or RRF in incident PD patients.

Patients and Methods

We identified all adults who underwent PD. The edema index was defined as the ratio of extracellular fluid to total body fluid. Participants with available data regarding survivorship or non-survivorship during the first year after PD initiation were included in the area under the receiver operating characteristic curve analysis. The cutoff value of the edema index for 1-year mortality was >0.371 in men and >0.372 in women. Participants were divided into two groups according to the cutoff value of their baseline edema indices: High (>cutoff value) and Low (≤cutoff value). Survivors during the first year after PD initiation were divided into two groups according to the initial and 1-year edema index: Non-improvement (maintenance of criteria in the initial Low group during the year) and Other (all participants except those in the Non-improvement group).

Results

In total, 631 patients were enrolled in the present study. The cutoff value of the edema index for 1-year mortality was >0.371 in men and >0.372 in women. The respective mean initial RRF values (mL·min^-1·1.73 m^-2) in the Low and High groups, respectively, were 4.88 ± 4.09 and 4.21 ± 3.28 in men (P = 0.108), and 3.19 ± 2.57 and 2.98 ± 2.70 in women (P = 0.531). There were no significant differences between groups in either sex. The respective mean RRF values at 1 year after PD initiation in the Low and High groups, respectively, were 3.56 ± 4.35 and 2.73 ± 2.53 in men, and 2.80 ± 2.36 and 1.85 ± 1.51 in women. RRF at 1 year after PD initiation was higher in the Low group than in the High group (men: P = 0.027; women: P = 0.001). In men, the cumulative 5-year survival rates were 78.7% and 46.2% in the Low and High groups, respectively, whereas in women, rates were 77.2% and 58.8% in the Low and High groups, respectively. For survivors during the first year after PD initiation, the Non-improvement group was associated with a poor survival rate compared with the Other group for both sexes.

Conclusion

A high edema index was associated with mortality in incident PD patients at baseline and follow-up. The edema index may be used as a new marker for predicting mortality in PD patients.

Impact of hyponatremia on frequency of complications in patients with decompensated liver cirrhosis

Introduction

Hyponatremia is common in cirrhosis. The relationship between hyponatremia and severity of cirrhosis is evidenced by its close association with the occurrence of complications, the prevalence of hepatic encephalopathy, hepatorenal syndrome, spontaneous bacterial peritonitis, refectory ascites, and hepatic hydrothorax. The aim of this study was assess the impact of hyponatremia on the occurrence of both liver-related complications and the hemodynamic cardiovascular dysfunction.

Methods

This prospective study was conducted in 2015 on 74 patients with liver cirrhosis. The patients were from the Gastroenterology and Hepatology Department of Theodor Bilharz Research Institute in Giza, Egypt. The patients were divided into three groups according to their serum level of sodium. Group 1 included 30 patients with serum sodium >135 meq/L, group 2 included 24 patients with serum sodium between135 and 125 meq/L, and group 3 included 20 patients with serum sodium <125 meq/L. For each of the patients, we conducted aclinical examination, laboratory investigations, chest X-ray, ECG, abdominal sonar, and echocardiography.

Results

Hyponatremia was found in 59.46% of our cirrhotic patients, and they showed significantly increased Model for End-Stage Liver Disease (MELD) score, MELD-Na score, QTc interval, Pulmonary vascular resistance (PVR) and inferior vena cava (IVC) collapsibility, and decreased SVR and IVC diameter. Also hepatic encephalopathy, ascites, renal failure, infectious complications, and pleural effusion were significantly more common in hyponatremic cirrhotic patients.

Conclusion

In cirrhosis, hyponatremia is more common in severe cardiovascular dysfunction and associated with increased risk of hepatic encephalopathy, ascites, illness severity scores, renal failure, infectious complications, and pleural effusion. We recommend selective oral administration of vasopressin V2-receptor antagonist, tolvaptan, which acts to increase the excretion of free water, thereby resolving hypervolemic hyponatremia and may have the potential to improve outcomes in these patients.

Systemic vascular resistance and fluid status in patients with decompensated liver cirrhosis with or without functional renal failure in Egypt

BACKGROUND

Functional renal failure and cardiovascular dysfunction are common complications of liver cirrhosis. This study aimed to evaluate cardiac performance, systemic vascular resistance (SVR) and fluid status in patients with decompensated liver cirrhosis either with or without functional renal failure.

METHODS

Sixty patients diagnosed as having decompensated liver cirrhosis were divided into two groups. Group 1 included 30 patients with decompensated liver cirrhosis with ascites and with creatinine values ≤ 1.5 mg/dl. Group 2 included 30 azotemic decompensated cirrhotic patients with diagnostic criteria of hepatorenal syndrome (HRS). Also, 20 healthy subjects, of matched age and sex to the Group 1 and Group 2 patients, were included in the study as the control group. All patients and normal controls were subjected to clinical examination, laboratory evaluation, ECG, abdominal ultrasonography and echocardiographic studies.

RESULTS

The echocardiographic and ECG data showed significant increase in LAD (P<0.01, P<0.01), AoD (P<0.05, P<0.01), interventricular septum thickness (IVST) (P<0.01, P<0.01), posterior wall thickness (PWT) (P<0.01, P<0.01), EDD (P<0.01, P<0.01), ESD (P<0.05, P<0.01), left ventricular (LV) mass (P<0.01, P<0.01), and Corrected QT (QTc) (P<0.01, P<0.01) interval with significant decrease in SVR (P<0.01, P<0.01). Additionally, there was significant decrease in IVC diameter in both patients groups compared to the control group (P<0.01, P<0.01).

CONCLUSION

Patients with decompensated liver cirrhosis have low SVR, and Doppler echocardiography provides an easy noninvasive tool to assess this finding. Also, these patients demonstrate small inferior vena cava (IVC) diameter with normal collapsibility, which indicates low effective plasma volume. Measuring IVC diameter and collapsibility are of value in the prediction of intravascular fluid status in liver cirrhosis. This is especially true with renal dysfunction. Early addition of oral vasoconstrictors in decompensated patients may correct the SVR and circulatory dysfunction and hinder HRS occurrence.

Inferior Vena Cava Assessment: Correlation with CVP and Plethora in Tamponade

Bedside assessment of intravascular volume status plays an important role in the management of critically ill patients, guiding fluid replacement therapy and the use of vasopressor agents. Despite controversy in the existing evidence, many clinicians advocate the use of inferior vena cava ultrasound (IVC-US) in the assessment of intravascular volume status in critically ill patients. Respirophasic variation in IVC diameter may provide useful information regarding intravascular volume status, particularly in patients with high and low caval indices. However, due to conflicting results of small-scale clinical trials of divergent sample populations, there is insufficient evidence to support routine US assessment of the IVC to determine fluid responsiveness in spontaneous breathing with circulatory compromise. Additional large-scale clinical trials are required to determine the accuracy of IVC-US measurements in diverse populations and to ascertain the effects on IVC dimensions that result from cardiac dysfunction and intra-abdominal hypertension.

Inferior vena cava diameter change after intravenous furosemide in patients diagnosed with acute decompensated heart failure

PURPOSE

Measurement of the inferior vena cava (IVC) diameters may improve decision-making for patients hospitalized with acute decompensated heart failure. Nevertheless, little is known about how the IVC is affected by loop diuretics. We sought to determine if bolus infusions of intravenous furosemide affect IVC diameters measured by hand-carried ultrasonography.

METHODS

We conducted a prospective cohort study at a public teaching hospital from September 2009 through June 2010. Physician investigators performed IVC ultrasonography on a convenience sample of 70 hospitalized adults who were prescribed intravenous furosemide for the diagnosis of acute decompensated heart failure.

RESULTS

Participants' median baseline IVC diameter was 2.38 cm (interquartile range, 1.91-2.55 cm). At 1-2 hours after furosemide, IVC diameters decreased an average of 0.21 cm (95% CI, 0.13-0.29 cm) and remained significantly below baseline at 2-3 hours after furosemide by an average of 0.15 cm (95% CI, 0.07-0.22 cm).

CONCLUSIONS

IVC diameters of adults diagnosed with acute decompensated heart failure become measurably smaller after single doses of intravenous furosemide. Whether this represents a true change in volume status has not been studied.

Non-invasive bedside assessment of central venous pressure: scanning into the future

BACKGROUND

Noninvasive evaluation of central venous pressure (CVP) can be achieved by assessing the Jugular Venous Pressure (JVP), Peripheral Venous Collapse (PVC), and ultrasound visualization of the inferior vena cava. The relative accuracy of these techniques compared to one another and their application by trainees of varying experience remains uncertain. We compare the application and utility of the JVP, PVC, and handheld Mini Echo amongst trainees of varying experience including a medical student, internal medicine resident, and cardiology fellow. We also introduce and validate a new physical exam technique to assess central venous pressures, the Anthem sign.

METHODS

Patients presenting for their regularly scheduled echocardiograms at the hospital echo department had clinical evaluations of their CVP using these non-invasive bedside techniques. The examiners were blinded to the echo results, each other's assessments, and patient history; their CVP estimates were compared to the gold standard level 3 echo-cardiographer's estimates at the completion of the study.

RESULTS

325 patients combined were examined (mean age 65, s.d. 16 years). When compared to the gold standard of central venous pressure by a level 3 echocardiographer, the JVP was the most sensitive at 86%, improving with clinical experience (p<0.01). The classic PVC technique and Anthem sign had better specificity compared to the JVP. Mini Echo estimates were comparable to physical exam assessments.

CONCLUSIONS

JVP evaluation is the most sensitive physical examination technique in CVP assessments. The PVC techniques along with the newly described Anthem sign may be of value for the early learner who still has not mastered the art of JVP assessment and in obese patients in whom JVP evaluation is problematic. Mini Echo estimates of CVPs are comparable to physical examination by trained clinicians and require less instruction. The use of Mini Echo in medical training should be further evaluated and encouraged.

Techniques for the assessment of volume status in patients with end stage renal disease

While advances in assessing extracellular volume status have occurred, no methodology is sufficiently robust and accurate in all patients to recommend routine use in clinical practice. All of the methods described also perform best when measured serially in patients and when correlated with other ancillary methods of volume assessment such as body weight, physical examination and determination of vital signs and symptomatology. Perhaps, the best method for assessing and modifying dry weight is to utilize multiple complementary methods such as advocated by Ronco et in the “5B” approach (39). In this approach, the clinician utilizes data from: fluid balance (body weight changes), blood pressure, biomarkers (such as the natriuretic peptides), bioimpedance, and blood volume changes. Body (thoracic and IVC) ultrasound can also be included (Fig. 1). These combined data sources will likely lead to greater detection of subtle volume overload, a finding likely to contribute to excess mortality and morbidity. Clinical trials of such strategies are needed to better inform clinicians.

Initial inferior vena cava diameter on computed tomographic scan independently predicts mortality in severely injured trauma patients

BACKGROUND

In the trauma population, patients with physiologic compromise may present with "normal" vital signs. We hypothesized that the inferior vena cava (IVC) diameter could be used as a surrogate marker for hypovolemic shock and predict mortality in severely injured trauma patients.

METHODS

A retrospective cohort study was performed at a Level I trauma center on 161 severely injured adult (aged ≥ 16 years) trauma patients who were transported from the scene and underwent abdominal computed tomography within 1 hour. Exposure of interest was dichotomously defined as having an infrarenal transverse to anteroposterior IVC ratio of ≥ 1.9 (flat IVC) or <1.9 (not exposed) based on the area under the curve analysis. The primary outcome was in-hospital mortality. Covariates included initial heart rate, systolic blood pressure, bicarbonate, base excess, creatinine, hemoglobin, and Injury Severity Score (ISS). Correlation analysis between IVC ratio and other known markers of hypoperfusion was performed. Logistic regression was used to determine the independent effect of the IVC ratio on mortality.

RESULTS

Of the 161 patients, 30 had a flat IVC. The IVC ratio had a significant (p < 0.05) inverse correlation with initial bicarbonate, hemoglobin, and base excess and a direct correlation with Cr and ISS. After controlling for age, ISS, and presence of severe head injury, patients who had a flat IVC were 8.1 times (95% confidence interval, 1.5-42.9) more likely to die compared with the nonexposed cohort. Importantly, heart rate and systolic blood pressure had no predictive value in this patient population.

CONCLUSION

A flat IVC on initial abdominal computed tomographic scan has a significant correlation with other known markers of shock and is an independent predictor of mortality in severely injured trauma patients. This finding should heighten the awareness of the need for aggressive intervention and potential for physiological decompensation in patients with otherwise "normal" vital signs.

LEVEL OF EVIDENCE

Prognostic study, level III.

Cardiopulmonary interactions and volume status assessment

Assessment of the hemodynamics and volume status is an important daily task for physicians caring for critically ill patients. There is growing consensus in the critical care community that the "traditional" methods-e.g., central venous pressure or pulmonary artery occlusion pressure-used to assess volume status and fluid responsiveness are not well supported by evidence and can be misleading. Our purpose is to provide here an overview of the knowledge needed by ICU physicians to take advantage of mechanical cardiopulmonary interactions to assess volume responsiveness. Although not perfect, such dynamic assessment of fluid responsiveness can be helpful particularly in the passively ventilated patients. We discuss the impact of phasic changes in lung volume and intrathoracic pressure on the pulmonary and systemic circulation and on the heart function. We review how respirophasic changes on the venous side (great veins geometry) and arterial side (e.g., stroke volume/systolic blood pressure and surrogate signals) can be used to detect fluid responsiveness or hemodynamic alterations commonly encountered in the ICU. We review the physiological limitations of this approach.

Left-sided and duplicate inferior vena cava: a case series and review

Left-sided and duplicate inferior vena cava (IVC) are two major anatomical variants within the spectrum of IVC malformations, both of which are developmental abnormalities of the supracardinal veins. Four clinical cases are described to highlight the computed tomographic appearances of these vascular malformations and provide novel data on venous dimensions. A systematic review of the recent literature (2000-2011) was conducted focusing on the anatomy, demographics, and associated pathology (congenital and acquired) of isolated left-sided and duplicate IVC. A total of 73 relevant articles were retrieved, consisting of case reports and small case series. The prevalence of left-sided IVC is about 0.1-0.4% and that for duplicate IVC about 0.3-0.4%; both anomalies show a slight male preponderance. In each condition, there are documented variations in the course and tributaries of the IVC. The clinical importance of these anomalies lies in three principal areas: the potential for misdiagnosis on imaging; technical difficulties during retroperitoneal surgery (particularly abdominal aortic aneurysm repair and live donor nephrectomy); and their significance in relation to the etiology and management of venous thromboembolism.

Role of inferior vena cava diameter in assessment of volume status: a meta-analysis

BACKGROUND AND OBJECTIVE

Hypovolemic shock is an important cause of death in the emergency department (ED). We sought to conduct a meta-analysis to quantify existing evidence on sonographic measurement of inferior vena cava (IVC) diameter in assessing of volume status adult ED patients.

METHODS

A search of 5 major databases of biomedical publication, EMBASE, Ovid Medline, evidence-based medicine (EBM) Reviews, Scopus, and Web of Knowledge, was performed in first week of March 2011. Studies meeting the following criteria were included: (1) prospectively conducted, (2) measured IVC diameter using ultrasonography, (3) inpatients under spontaneous ventilation, and (4) reported IVC diameter measurement with volume status or shock. Article search, study quality assessment, and data extraction were done independently and in duplicate. Mean difference in IVC diameter was calculated using RevMan version 5.5 (Cochrane collaboration).

RESULTS

A total of 5 studies qualified for study eligibility from 4 different countries, 3 being case-control and 2 before-and-after design, studying 86 cases and 189 controls. Maximal IVC diameter was significantly lower in hypovolemic status compared with euvolemic status; mean difference (95% confidence interval) was 6.3 mm (6.0-6.5 mm). None of the studies blinded interpreters for volume status of participants.

CONCLUSION

Moderate level of evidence suggests that the IVC diameter is consistently low in hypovolemic status when compared with euvolemic. Further blinded studies are needed before it could be used in the ED with confidence.

Does a simple bedside sonographic measurement of the inferior vena cava correlate to central venous pressure?

BACKGROUND

Bedside ultrasound has been suggested as a non-invasive modality to estimate central venous pressure (CVP).

OBJECTIVE

Evaluate a simple bedside ultrasound technique to measure the diameter of the inferior vena cava (IVC) and correlate to simultaneously measured CVP. Secondary comparisons include anatomic location, probe orientation, and phase of respiration.

METHODS

An unblinded prospective observation study was performed in an emergency department and critical care unit. Subjects were a convenience sample of adult patients with a central line at the superior venocaval-atrial junction. Ultrasound measured transverse and longitudinal diameters of the IVC at the subxiphoid, suprailiac, and mid-abdomen, each measured at end-inspiration and end-expiration. Correlation and regression analysis were used to relate CVP and IVC diameters.

RESULTS

There were 72 subjects with a mean age of 67 years (range 21-94 years), 37 (53%) male, enrolled over 9 months. Seven subjects were excluded for tricuspid valvulopathy. Primary diagnoses were: respiratory failure 12 (18%), sepsis 11 (17%), and pancreatitis 3 (5%). There were 28 (43%) patients mechanically ventilated. Adequate measurements were obtainable in 57 (89%) using the subxiphoid, in 44 (68%) using the mid-abdomen, and in 28 (43%) using the suprailiac views. The correlation coefficients were statistically significant at 0.49 (95% confidence interval [CI] 0.26-0.66), 0.51 (95% CI 0.23-0.71), and 0.50 (95% CI 0.14-0.74) for end-inspiratory longitudinal subxiphoid, midpoint, and suprailiac views, respectively. Transverse values were statistically significant at 0.42 (95% CI 0.18-0.61), 0.38 (95% CI 0.09-0.61), and 0.67 (95% CI 0.40-0.84), respectively. End-expiratory measurements gave similar or slightly less significant values.

CONCLUSION

The subxiphoid was the most reliably viewed of the three anatomic locations; however, the suprailiac view produced superior correlations to the CVP. Longitudinal views generally outperformed transverse views. A simple ultrasound measure of the IVC yields weak correlation to the CVP.

Estimation of normal hydration in dialysis patients using whole body and calf bioimpedance analysis

Prescription of an appropriate dialysis target weight (dry weight) requires accurate evaluation of the degree of hydration. The aim of this study was to investigate whether a state of normal hydration (DW(cBIS)) as defined by calf bioimpedance spectroscopy (cBIS) and conventional whole body bioimpedance spectroscopy (wBIS) could be characterized in hemodialysis (HD) patients and normal subjects (NS). wBIS and cBIS were performed in 62 NS (33 m/29 f) and 30 HD patients (16 m/14 f) pre- and post-dialysis treatments to measure extracellular resistance and fluid volume (ECV) by the whole body and calf bioimpedance methods. Normalized calf resistivity (ρ(N)(,5)) was defined as resistivity at 5 kHz divided by the body mass index. The ratio of wECV to total body water (wECV/TBW) was calculated. Measurements were made at baseline (BL) and at DW(cBIS) following the progressive reduction of post-HD weight over successive dialysis treatments until the curve of calf extracellular resistance is flattened (stabilization) and the ρ(N)(,5) was in the range of NS. Blood pressures were measured pre- and post-HD treatment. ρ(N)(,5) in males and females differed significantly in NS. In patients, ρ(N)(,5) notably increased with progressive decrease in body weight, and systolic blood pressure significantly decreased pre- and post-HD between BL and DW(cBIS) respectively. Although wECV/TBW decreased between BL and DW(cBIS), the percentage of change in wECV/TBW was significantly less than that in ρ(N)(,5) (-5.21 ± 3.2% versus 28 ± 27%, p < 0.001). This establishes the use of ρ(N)(,5) as a new comparator allowing a clinician to incrementally monitor removal of extracellular fluid from patients over the course of dialysis treatments. The conventional whole body technique using wECV/TBW was less sensitive than the use of ρ(N)(,5) to measure differences in body hydration between BL and DW(cBIS).

Two types of orthostatic dysregulation assessed by diameter of inferior vena cava

AIMS

Orthostatic dysregulation (OD) is common in adolescents. This study was conducted to evaluate the usefulness of the measurement of the diameter of the inferior vena cava (IVC) for objective assessment of patients with OD.

METHODS

Twenty children with OD (median 14 years, range 9-15 years) and 23 age-matched healthy children (median 12 years, range 10-15 years) were enrolled. A diameter of IVC was measured by an abdominal echogram before and after a head-up tilt table testing (HUT). Changes in IVC was assessed by an arbitrary parameter, collapse index (CI) as the following equation: [(maximal IVC diameter in the supine position - maximal IVC diameter in the standing position)/(maximal IVC diameter in the supine position)]× 100. CI was evaluated 4 weeks after treatment with an adrenergic agent.

RESULTS

Children with OD demonstrated either higher CI or lower CI compared to that in control children: CI was more than 50 (range 50-71) in 12 patients with OD while that was equal to or less than 0 (range -225 to 0) in eight out of 20 patients. In contrast, CI was between 0 and 50 (range 1-26) in 23 healthy children. Pharmacological treatment induced the normalization in the CI in both higher and lower CI group.

CONCLUSION

OD can be classified into two subtypes: by HUT, one is characterized by an increase of IVC diameter while another is characterized by its decrease. Measurement of IVC diameter by HUT is useful to understand the pathophysiology and to assess the efficacy of treatment.

Tissue Doppler of early mitral filling correlates with simulated volume loss in healthy subjects

OBJECTIVES

The accurate noninvasive assessment of preload in emergency department (ED) patients remains elusive. Point-of-care ultrasound (US) imaging, particularly evaluation of the inferior vena cava (IVC), has been shown to be qualitatively helpful. Doppler and tissue Doppler are now routinely available on ED US equipment, but few studies have looked at the correlation of dynamic changes in these parameters in a controlled model of hypovolemia. Our objective was to examine the correlation of Doppler parameters to simulated volume loss in healthy subjects using a lower-body negative pressure (LBNP) model and to compare these measurements to commonly used IVC measurements of preload.

METHODS

Twelve paid volunteers with no known cardiovascular disease between the ages of 23 and 31 years old (mean ± SD = 25.5 ± 2.5 years old) were recruited. Hypovolemia was simulated using graduated LBNP levels with measurements taken at 0, -30, and -60 mm Hg and lower pressures as tolerated. Vital signs were monitored in all patients. US measurements recorded at each negative pressure level included IVC maximum (IVC(max)) and minimum (IVC(min)) dimensions; early (E) and late (A) transmitral filling velocities using pulsed-wave spectral Doppler; and early (E') and late (A') tissue Doppler velocities at the septal ((sep)) and lateral ((lat)) mitral annulus, using pulsed-wave tissue Doppler.

RESULTS

Lower-body negative pressure correlated significantly and positively within subjects for all US parameters except for the A filling wave. E'(lat) and E'(sep) showed the strongest correlation with R² values of 0.749 (95% confidence interval [CI] = 0.577 to 0.854) and 0.738 (95% CI = 0.579 to 0.875) respectively, followed by A'(sep) 0.674 (95% CI = 0.416 to 0.845), IVC(max) 0.638 (95% CI = 0.425 to 0.806), A'(lat) 0.547 (95% CI = 0.280 to 0.802), IVC(min) 0.512 (95% CI = 0.192 to 0.777), and E 0.478 (95% CI = 0.187 to 0.762). Ratios correlated only moderately with LBNP level, including E/ E'(lat) R² of 0.430 (95% CI = 0.131 to 0.706), E/ E'(sep) 0.416 (95% CI = 0.183 to 0.686), and IVC collapsibility index (IVC(CI)) 0.201 (95% CI = 0.003 to 0.681). Vital signs, including heart rate and blood pressure, did not vary significantly with LBNP levels.

CONCLUSIONS

In this pilot study of healthy subjects, tissue Doppler assessment of early diastolic filling correlated most strongly with simulated hypovolemia.

Clinician performed resuscitative ultrasonography for the initial evaluation and resuscitation of trauma

BACKGROUND

Traumatic injury is a leading cause of morbidity and mortality in developed countries worldwide. Recent studies suggest that many deaths are preventable if injuries are recognized and treated in an expeditious manner - the so called 'golden hour' of trauma. Ultrasound revolutionized the care of the trauma patient with the introduction of the FAST (Focused Assessment with Sonography for Trauma) examination; a rapid assessment of the hemodynamically unstable patient to identify the presence of peritoneal and/or pericardial fluid. Since that time the use of ultrasound has expanded to include a rapid assessment of almost every facet of the trauma patient. As a result, ultrasound is not only viewed as a diagnostic test, but actually as an extension of the physical exam.

METHODS

A review of the medical literature was performed and articles pertaining to ultrasound-assisted assessment of the trauma patient were obtained. The literature selected was based on the preference and clinical expertise of authors.

DISCUSSION

In this review we explore the benefits and pitfalls of applying resuscitative ultrasound to every aspect of the initial assessment of the critically injured trauma patient.

Predicting the development of anemia by measuring the diameter of the inferior vena cava of patients with spinal cord injury

PURPOSE AND METHODS

We retrospectively investigated whether measurement of the diameter of the inferior vena cava (IVC) is useful in predicting the development of anemia in 12 patients with spinal cord injury. Measurement of the IVC was performed in conjunction with computed tomography scan upon arrival. The subjects were divided into two groups: those with a minimum (Min) hemoglobin (Hb) of less than 10 g/dL, and those with a Min Hb greater than 10 g/dL during hospitalization.

RESULTS

The average diameter of IVC in the Hb<10 g/dL group was smaller that that in the Hb>10g/dL group. Blood pressure was not significantly different between the two groups. The difference between the Min and initial Hb value and incidence of blood transfusion in the Hb<10g/dL group was significantly greater than that in the Hb>10g/dL group.

CONCLUSION

To predict the development of anemia, measurement of the IVC of patients with spinal cord injury may therefore be useful.

Hypovolemic shock evaluated by sonographic measurement of the inferior vena cava during resuscitation in trauma patients

BACKGROUND

Inferior vena cava (IVC) diameter immediately after fluid resuscitation has not yet been investigated in trauma patients with shock on arrival.

METHODS

Between June 2004 and May 2005, 30 trauma patients with hemorrhagic shock were prospectively investigated. Using ultrasound, we measured maximum anterior-posterior diameter of the IVC just below the diaphragm in the hepatic segment, in the expiratory phase. This was performed on arrival and when systolic blood pressure had been raised to over 90 mm Hg by fluid resuscitation in the emergency room. Subjects were divided into two groups: a transient responder group (n = 17) in which shock recurred after leaving the emergency room and a responder group (n = 13) in which blood pressure remained stable.

RESULTS

There were no significant differences between the two groups regarding age or gender, or regarding vital signs or IVC diameter on arrival. Average injury severity score in the transient responder group was significantly greater than that in the responder group. After fluid resuscitation, no significant intergroup differences were observed regarding vital signs. However, IVC diameter was significantly smaller in the transient responder group than in the responder group (6.5 +/- 0.5 mm; mean +/- SE vs. 10.7 +/- 0.7 mm, p < 0.05).

CONCLUSION

In trauma patients, inadequate dilatation of the IVC by fluid resuscitation, might indicate insufficient circulating blood volume despite normalization of blood pressure. In this small study, IVC diameter appeared a better predictor of recurrence of shock than blood pressure, heart rate, or arterial base excess. A larger prospective study is called for to clearly establish the sensitivity and specificity of this method.