Inferior vena cava diameter: a useful method for estimation of fluid status in children on haemodialysis

Assessment of volume status of pediatric hemodialysis patients

BACKGROUND

Accurate volume status assessment and dry weight achievement are the most challenging goals for a nephrologist. We aimed to evaluate the role of ultrasonographic parameters including lung ultrasound and inferior vena cava (IVC) measurements as practical methods of volume status assessment in children on hemodialysis by comparing them with established techniques, such as clinical evaluation and bioimpedance spectroscopy.

METHODS

A prospective cross-sectional study compared pre- and post-dialysis volume status using bioimpedance spectroscopy (BIS) parameters and clinical data with ultrasonographic lung B-lines and IVC parameters in children on regular hemodialysis.

RESULTS

A total 60 children (mean age 9.4 ± 2.8 years) were enrolled. Twenty patients (33.3%) were clinically overloaded to varying degrees (17 patients had mild to moderate signs of fluid overload and 3 patients had moderate to severe signs of fluid overload). All other patients (66.7%) were clinically euvolemic. Sonographic parameters were significantly lower post-dialysis than pre-dialysis, including lung B-line count and IVC diameter. IVC collapsibility index mean was significantly higher post-dialysis than pre-dialysis. There was a significant correlation between the lung B-line count, IVC parameters, and BIS-measured overhydration both before and after hemodialysis. Nine patients had ≥ 8 B-lines post-dialysis, only three of them were hypertensive.

CONCLUSIONS

Clinical criteria alone are not specific for determining accurate fluid status in pediatric hemodialysis patients. Lung B-line score, IVC parameters, and BIS may be complementary to each other and to clinical data. Lung B-lines outperform IVC measurements and BIS in subclinical volume overload detection in pediatric hemodialysis patients.

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.

Assessment of fluid removal using ultrasound, bioimpedance and anthropometry in pediatric dialysis: a pilot study

BACKGROUND

Fluid overload is associated with morbidity and mortality in children receiving dialysis. Accurate clinical assessment is difficult, and using deuterium oxide (D₂O) to measure total body water (TBW) is impractical. We investigated the use of ultrasound (US), bioimpedance spectroscopy (BIS), and anthropometry to assess fluid removal in children receiving maintenance hemodialysis (HD).

METHODS

Participants completed US, BIS, and anthropometry immediately before and 1-2 h after HD for up to five sessions. US measured inferior vena cava (IVC) diameter, lung B-lines, muscle elastography, and dermal thickness. BIS measured the volume of extracellular (ECF) and intracellular (ICF) fluid. Anthropometry included mid-upper arm, calf and ankle circumferences, and triceps skinfold thickness. D₂O was performed once pre-HD. We assessed the change in study measures pre- versus post-HD, and the correlation of change in study measures with percent change in body weight (%∆BW). We also assessed the agreement between TBW measured by BIS and D₂O.

RESULTS

Eight participants aged 3.4-18.5 years were enrolled. Comparison of pre- and post-HD measures showed significant decrease in IVC diameters, lung B-lines, dermal thickness, BIS %ECF, mid-upper arm circumference, ankle, and calf circumference. Repeated measures correlation showed significant relationships between %∆BW and changes in BIS ECF (r_rm =0.51, 95% CI 0.04, 0.80) and calf circumference (r_rm=0.80, 95% CI 0.51, 0.92). BIS TBW correlated with D₂O TBW but overestimated TBW by 2.2 L (95% LOA, -4.75 to 0.42).

CONCLUSION

BIS and calf circumference may be helpful to assess changes in fluid status in children receiving maintenance HD. IVC diameter, lung B-lines and dermal thickness are potential candidates for future studies.

High Inferior Vena Cava Diameter with High Left Ventricular End Systolic Diameter as a Risk Factor for Major Adverse Cardiovascular Events, Cardiovascular and Overall Mortality among Chronic Hemodialysis Patients

Background: Little is known about the association of inferior vena cava diameter (IVCD) and left ventricular end-systolic diameter (LVESD) with mortality in patients undergoing hemodialysis (HD). Methods: The single medical center observational cohort study enrolled 241 adult chronic HD patients from 1 October 2018 to 31 December 2018. Echocardiography results of IVCD and LVESD prior to dialysis were retrieved and patients were divided into high IVCD and low IVCD groups. Patients who received HD via a tunneled cuffed catheter were excluded. Study outcomes included all-cause mortality, cardiovascular mortality, and major adverse cardiovascular events (MACE). Subgroup analyses of HD patients with high and low LVESD were also performed. Results: The incidence of all-cause mortality, cardiovascular mortality, and MACE were higher in chronic HD patients with high IVCD (p < 0.01). High IVCD patients had significantly greater all-cause mortality, cardiovascular mortality, and MACE (log-rank test; p < 0.05). High IVCD patients are also associated with an increased risk of all-cause mortality and MACE relative to low IVCD patients (aHRs, 2.88 and 3.42; 95% CIs, 1.06−7.86 and 1.73−6.77, respectively; all p < 0.05). In the subgroup analysis of patients with high or low LVESD, the high IVCD remained a significant risk factor for all-cause mortality and MACE, and the HR is especially high in the high LVESD group. Conclusions: Dilated IVCD is a risk factor for all-cause mortality and MACE in chronic HD patients. In addition, these patients with high LVESD also have a significantly higher HR of all-cause mortality and MACE.

A new technique for the detection of dry weight in hemodialysis patients: Estimated pulmonary capillary wedge pressure. A tissue Doppler imaging study

BACKGROUND AND OBJECTIVE

Fluid overload is an important factor of morbidity and mortality in hemodialysis patients. Today correct determination of dry weight (DW) remains an important issue of hemodialysis practice. Within this context, it is subjected to new method searching. The objective of this study was to calculate estimated pulmonary capillary wedge pressure (ePCWP) with Tissue Doppler Imaging (TDI) in hemodialysis patients and to evaluate its correlation with the other volume markers and to evaluate whether it can be a new method for detection of DW.

MATERIALS AND METHODS

Echocardiographic, hemodynamic, and biochemical volume markers of 41 hemodialysis patients were evaluated in the pre- and post-dialysis periods. Patients were divided into two groups based on ePCWP values (Group 1 ePCWP<20mmHg, Group 2 ePCWP>20mmHg).

RESULTS

In the pre-dialysis period; parameters related to volume load including ePCWP, systolic blood pressure, mean arterial pressure, pulse pressure, left atrial diameter, left atrial volume, E/é, ratio and E/V_p ratio were statistically significantly higher in Group2 compared to Group1. On the other hand, strong correlations were found between pre-dialysis ePCWP and systolic blood pressure, mean arterial pressure, pulse pressure, NT-ProBNP, left atrial diameter, E/é ratio and E/V_p ratio.

CONCLUSIONS

Strong correlations found between ePCWP which was calculated with TDI and the other volume markers both in pre-dialysis and post-dialysis periods. These findings can provide a significant contribution to routine evaluating of DW in hemodialysis patients. From this aspect, the prediction of ePCWP with TDI can be a new practical and reproducible method for the determination of DW.

Copeptin Concentrations in Plasma of Healthy Neonates in Relation to Water–Electrolyte Homeostasis in the Early Adaptation Period

Copeptin (CTproAVP) is a stable by-product of arginine–vasopressin synthesis and reflects its secretion by the pituitary gland, considered as a potential new marker of dehydration. The objective of the study was to investigate CTproAVP measured after the first 48 h of postnatal life in relation to serum effective osmolality, urine osmolality, and vessels filling according to the following variables: delivery mode, postnatal weight loss, fluids administered intravenously to the mother, and fluids given orally to the neonate. A prospective observational study was conducted with 200 healthy term infants (53% male) enrolled. Serum CTproAVP concentrations were measured using the ELISA kit; haematocrit, urine osmolality, serum effective osmolality were assessed after 48 h of life. Sonographic measurements of inferior vena cava (IVC) and aorta (Ao) were performed and IVC/Ao ratios were calculated. No correlations were found between CTproAVP concentrations and both serum effective osmolality and urine osmolality. There was also no association between CTproAVP concentrations and vessel filling represented by IVC/Ao index at 48 h of life.

Assessment of volemia status using ultrasound examination of the inferior vena cava and spectroscopic bioimpendance in hemodialysis patients

Background/Aim. Hypervolemia is an important risk factor for the development of cardiovascular morbidity and mortality in patients treated with regular hemodialysis. There is still no reliable method for assessing the status of volemia in these patients. The aim of the study was to assess the status of volemia in patients treated with regular hemodialysis by measuring the parameters of the inferior vena cava (IVC) and bioimpedance. Methods. The effect of hemodialysis treatment on ultrasound parameters of the IVC, as well as on the parameters measured by bioimpedance, was examined before and after hemodialysis. The values of the N-terminal prohormone of brain natriuretic peptide (NT-proBNP) were measured both before and after hemodialysis. Forty-five patients were involved in this non-interventional cross-section study, including the patients treated with standard bicarbonate dialysis. According to the interdialytic yield, the patients were divided into three groups: I (up to 2,000 mL), II (2,000?3,000 mL), and III (over 3,000 mL). Results. The values of the IVC parameters and the parameters measured with bioimpedance were significantly lower after treatment with hemodialysis (p < 0.005). The third group of patients had a significantly higher total fluid volume in the body com-pared to the group I, as well as a significantly greater volume of extracellular fluid (p < 0.005). The significantly lower values of NT-proBNP in all groups (p < 0.005) were detected after hemodialysis. After treatment with hemodialysis, a positive correlation was observed between the concentration of NT-proBNP in the serum and the extracellular/intracellular water ratio. However, the correlation between NT-proBNP concentration and total fluid measured by bioimpedance spectroscopy did not reach statistical significance. Conclusion. Measurement of the IVC ultrasound parameters and volemia parameters using bioimpedance significantly contributes to the assessment of the status of volemia. Nevertheless, it cannot be used as a separate parameter, only in combination with all other methods.

A new technique for the detection of dry weight in hemodialysis patients: Estimated pulmonary capillary wedge pressure. A tissue Doppler imaging study

BACKGROUND AND OBJECTIVE

Fluid overload is an important factor of morbidity and mortality in hemodialysis patients. Today correct determination of dry weight (DW) remains an important issue of hemodialysis practice. Within this context, it is subjected to new method searching. The objective of this study was to calculate estimated pulmonary capillary wedge pressure (ePCWP) with Tissue Doppler Imaging (TDI) in hemodialysis patients and to evaluate its correlation with the other volume markers and to evaluate whether it can be a new method for detection of DW.

MATERIALS AND METHODS

Echocardiographic, hemodynamic, and biochemical volume markers of 41 hemodialysis patients were evaluated in the pre- and post-dialysis periods. Patients were divided into two groups based on ePCWP values (Group 1 ePCWP<20mmHg, Group 2 ePCWP>20mmHg).

RESULTS

In the pre-dialysis period; parameters related to volume load including ePCWP, systolic blood pressure, mean arterial pressure, pulse pressure, left atrial diameter, left atrial volume, E/é, ratio and E/Vp ratio were statistically significantly higher in Group2 compared to Group1. On the other hand, strong correlations were found between pre-dialysis ePCWP and systolic blood pressure, mean arterial pressure, pulse pressure, NT-ProBNP, left atrial diameter, E/é ratio and E/Vp ratio.

CONCLUSIONS

Strong correlations found between ePCWP which was calculated with TDI and the other volume markers both in pre-dialysis and post-dialysis periods. These findings can provide a significant contribution to routine evaluating of DW in hemodialysis patients. From this aspect, the prediction of ePCWP with TDI can be a new practical and reproducible method for the determination of DW.

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.

Volume Balance in Chronic Kidney Disease: Evaluation Methodologies and Innovation Opportunities

BACKGROUND

Patients affected by chronic kidney disease are at a risk of cardiovascular morbidity and mortality. Body fluids unbalance is one of the main characteristics of this condition, as fluid overload is highly prevalent in patients affected by the cardiorenal syndrome.

SUMMARY

We describe the state of the art and new insights into body volume evaluation. The mechanisms behind fluid balance are often complex, mainly because of the interplay of multiple regulatory systems. Consequently, its management may be challenging in clinical practice and even more so out-of-hospital. Availability of novel technologies offer new opportunities to improve the quality of care and patients' outcome. Development and validation of new technologies could provide new tools to reduce costs for the healthcare system, promote personalized medicine, and boost home care. Due to the current COVID-19 pandemic, a proper monitoring of chronic patients suffering from fluid unbalances is extremely relevant. Key Message: We discuss the main mechanisms responsible for fluid overload in different clinical contexts, including hemodialysis, peritoneal dialysis, and heart failure, emphasizing the potential impact provided by the implementation of the new technologies.

Clinical Relevance of Fluid Volume Status Assessment by Bioimpedance Spectroscopy in Children Receiving Maintenance Hemodialysis or Peritoneal Dialysis

Bioimpedance spectroscopy (BIS) is a noninvasive method used to evaluate body fluid volume status in dialysis patients, but reports on its effectiveness in pediatrics are scarce. We investigated the correlation between BIS and clinical characteristics and identified the changes in patients whose dialysis prescription was modified based on BIS. The medical records of children on maintenance dialysis who had undergone BIS between 2017 and 2019 were reviewed. Of the 49 patients, 14 were overhydrated, based on the >15% proportion of overhydration relative to extracellular water (OH/ECW) measured by BIS. Intake of ≥two antihypertensive medications was noted in the majority (85.7%) of children with fluid overload and only in 48.6% of those without fluid overload (p = 0.017). Elevated blood pressure despite medication use was significantly more common in patients with fluid overload than in those without fluid overload (78.6% vs. 45.7%, p = 0.037). Of the 14 overhydrated children, 13 (92.9%) had significant changes in body weight, OH/ECW, the number of antihypertensive drugs, left ventricular end-diastolic diameter, and cardiothoracic ratio after the change in dialysis prescription. BIS is a useful and noninvasive method to assess fluid status in dialysis children. Long-term follow-up and correlation with a more objective clinical indicator of fluid overload is necessary to verify the clinical effectiveness of BIS.

Evaluation of Hypervolemia in Children

Hypervolemia is a condition with an excess of total body water and when sodium (Na) intake exceeds output. It can have different causes, such as hypervolemic hyponatremia (often associated with decreased, effective circulating blood volume), hypervolemia associated with metabolic alkalosis, and end-stage renal disease. The degree of hypervolemia in critically ill children is a risk factor for mortality, regardless of disease severity. A child (under 18 years of age) with hypervolemia requires fluid removal and fluid restriction. Diuretics are able to increase or maintain urine output and thus improve fluid and nutrition management, but their benefit in preventing or treating acute kidney injury is questionable.

Fluid and hemodynamic management in hemodialysis patients: challenges and opportunities

Fluid volume and hemodynamic management in hemodialysis patients is an essential component of dialysis adequacy. Restoring salt and water homeostasis in hemodialysis patients has been a permanent quest by nephrologists summarized by the ‘dry weight’ probing approach. Although this clinical approach has been associated with benefits on cardiovascular outcome, it is now challenged by recent studies showing that intensity or aggressiveness to remove fluid during intermittent dialysis is associated with cardiovascular stress and potential organ damage. A more precise approach is required to improve cardiovascular outcome in this high-risk population. Fluid status assessment and monitoring rely on four components: clinical assessment, non-invasive instrumental tools (e.g., US, bioimpedance, blood volume monitoring), cardiac biomarkers (e.g. natriuretic peptides), and algorithm and sodium modeling to estimate mass transfer. Optimal management of fluid and sodium imbalance in dialysis patients consist in adjusting salt and fluid removal by dialysis (ultrafiltration, dialysate sodium) and by restricting salt intake and fluid gain between dialysis sessions. Modern technology using biosensors and feedback control tools embarked on dialysis machine, with sophisticated analytics will provide direct handling of sodium and water in a more precise and personalized way. It is envisaged in the near future that these tools will support physician decision making with high potential of improving cardiovascular outcome.

Caval Aortic Index: A Novel Tool for Fluid Assessment in Obstetric Emergencies

Background:

Uncorrected maternal hypotension occurring during obstetric emergencies may result in maternal and fetal morbidity. Fluid status of the pregnant mother is a major variable which affects the maternal hemodynamics during patient management, and there is no objective assessment tool for the same. A relatively new sonographic parameter, the inferior vena cava aorta (IVC/Ao) diameter index or caval aortic index, showed promise in this regard, and its application was studied in obstetric patients.

Methodology:

A prospective analytical study was conducted involving 50 pregnant and 50 nonpregnant women of reproductive age group. Using both subxiphoid and transhepatic views, their normal fasting caval aortic indices were determined from the ratio of mean IVC diameter to the mean aortic diameter. Descriptive and inferential statistical analyses were carried out accordingly.

Results:

Normal IVC/Ao diameter index for nonpregnant healthy women of reproductive age was 1.11 ± 0.29 in the subxiphoid view and 1.21 ± 0.33 in the transhepatic view. The difference between the two views was not statistically significant. IVC/Ao diameter index for a normal term pregnant woman was 1.03 ± 0.26, and term pregnancy does not significantly cause variation in the index.

Conclusions:

Caval aortic index is a useful noninvasive tool to assess volume status and guide fluid management in pregnant women presenting to the emergency department, and the transhepatic view is comparable to the traditional subxiphoid view for the measurement of the same.

Diagnostic efficacy of bedside ultrasound to detect dehydration in older patients attending an emergency care unit

BACKGROUND

The diagnosis of dehydration in older patients remains a challenge because clinical and laboratory signs are unspecific. The use of B‑Mode ultrasound of the inferior vena cava is proposed to aid in the diagnosis but data concerning diagnostic efficacy of bedside ultrasound are lacking.

METHODS

In this study 78 patients ≥65 years old referred to the emergency unit of a university hospital and identified as being dehydrated by applying clinical signs were compared with a reference of 121 patients. The diameter of the inferior vena cava (IVC) was assessed by ultrasound while compressing the IVC during an inspiratory maneuver and the minimum and maximum diameter in M‑Mode.

RESULTS

Significant differences were found concerning compressibility, variability of the diameter assessed by M‑Mode and the diameter during an inspiratory maneuver of the IVC (<0.001); however, a receiver operator characteristics (ROC) showed only moderate values for diagnostic efficacy for all these parameters where the best result was found for the inspiratory maneuver (Area under the curve [AUC] = 0.73). To reach a specificity of 0.8 to diagnose dehydration, a cut-off value of ≤0.4 cm for IVC diameter was suitable.

CONCLUSION

Ultrasound of the IVC can easily be applied in a bedside setting and may be helpful in identifying dehydration in older patients; however, this remains challenging and a synopsis covering clinical and technical data is indispensable.

Sodium and water handling during hemodialysis: new pathophysiologic insights and management approaches for improving outcomes in end-stage kidney disease

Space medicine and new technology such as magnetic resonance imaging of tissue sodium stores (²³NaMRI) have changed our understanding of human sodium homeostasis and pathophysiology. It has become evident that body sodium comprises 3 main components. Two compartments have been traditionally recognized, namely one that is circulating and systemically active via its osmotic action, and one slowly exchangeable pool located in the bones. The third, recently described pool represents sodium stored in skin and muscle interstitium, and it is implicated in cell and biologic activities via local hypertonicity and sodium clearance mechanisms. This in-depth review provides a comprehensive view on the pathophysiology and existing knowledge gaps of systemic hemodynamic and tissue sodium accumulation in dialysis patients. Furthermore, we discuss how the combination of novel technologies to quantitate tissue salt accumulation (e.g., ²³NaMRI) with devices to facilitate the precise attainment of a prescribed hemodialytic sodium mass balance (e.g., sodium and water balancing modules) will improve our therapeutic approach to sodium management in dialysis patients. While prospective studies are required, we think that these new diagnostic and sodium balancing tools will enhance our ability to pursue more personalized therapeutic interventions on sodium and water management, with the eventual goal of improving dialysis patient outcomes.

Ultrasound-based clinical profiles for predicting the risk of intradialytic hypotension in critically ill patients on intermittent dialysis: a prospective observational study

BACKGROUND

Intradialytic hypotension, a complication of intermittent hemodialysis, decreases the efficacy of dialysis and increases long-term mortality. This study was aimed to determine whether different predialysis ultrasound cardiopulmonary profiles could predict intradialytic hypotension.

METHODS

This prospective observational single-center study was performed in 248 critically ill patients with acute kidney injury undergoing intermittent hemodialysis. Immediately before hemodialysis, vena cava collapsibility was measured by vena cava ultrasound and pulmonary congestion by lung ultrasound. Factors predicting intradialytic hypotension were identified by multiple logistic regression analysis.

RESULTS

Intradialytic hypotension was observed in 31.9% (n = 79) of the patients, interruption of dialysis because of intradialytic hypotension occurred in 6.8% (n = 31) of the sessions, and overall 28-day mortality was 20.1% (n = 50). Patients were classified in four ultrasound profiles: (A) 108 with B lines > 14 and vena cava collapsibility > 11.5 mm m^-2, (B) 38 with B lines < 14 and vena cava collapsibility ≤ 11.5 mm m^-2, (C) 36 with B lines > 14 and vena cava collapsibility Di ≤ 11.5 mm m^-2, and (D) 66 with B lines < 14 and vena cava collapsibility > 11.5 mm m^-2. There was an increased risk of intradialytic hypotension in patients receiving norepinephrine (odds ratios = 15, p = 0.001) and with profiles B (odds ratios = 12, p = 0.001) and C (odds ratios = 17, p = 0.001).

CONCLUSION

In critically ill patients on intermittent hemodialysis, the absence of hypervolemia as assessed by lung and vena cava ultrasound predisposes to intradialytic hypotension and suggests alternative techniques of hemodialysis to provide better hemodynamic stability.

Quantitative Time-Harmonic Ultrasound Elastography of the Abdominal Aorta and Inferior Vena Cava

The purpose of this study was to evaluate the sensitivity of quantitative time-harmonic ultrasound elastography (THE) of the inferior vena cava (IVC) and abdominal aorta (AA) to changes in central volume status. THE of the IVC and AA was performed in 20 healthy volunteers before and after oral intake of 1 L of water and before or during passive leg raising to augment venous filling. Compound maps of shear wave speed (SWS) as surrogate measures of vessel wall stiffness were generated within the full field of view from multifrequency harmonic wave fields. SWS was measured in regions of the IVC and AA. Blood pressure, stroke volume, cardiac output and pulse wave velocity were recorded. Statistical significance of SWS changes was tested using one-way repeated-measures analysis of variance. SWS measured in the IVC increased from 1.71 ± 0.1 m/s before water intake to 1.82 ± 0.1 m/s during passive leg raising and, further, to 1.87 ± 0.1 m/s after hydration and to 1.95 ± 0.1 m/s with hydration plus passive leg raising (p < 0.001). SWS in the AA did not change significantly after hydration (2.14 ± 0.13 m/s vs. 2.15 ± 0.16 m/s; p = 0.792). SWS was significantly higher in the AA than in the IVC across all experiments (p < 0.001). Water drinking did not significantly influence blood pressure, pulse wave velocity and cardiac output (all p values >0.1), whereas stroke volume increased significantly (p = 0.031). Time-harmonic ultrasound elastography enables quantification of the wall stiffness of the large abdominal vessels and is sensitive to different volume and pressure states in the IVC.

A Deployable Transseptal Brace for Stabilizing Cardiac Catheters

A bracing device for stabilizing cardiac catheters inside the heart was developed to provide surgical-level dexterity to minimally invasive catheter-based procedures for cardiac valve disease. The brace was designed to have a folding structure, which lies flat along a catheter during navigation through vasculature and then unfolds into a rigid bracing configuration after deployment across the interatrial septum. The brace was designed to be easily deployable, provide bracing support for a transseptal catheter, and also be compliant enough to be delivered to the heart via tortuous vasculature. This aims to improve dexterity in catheter-based mitral valve repair and enable other complex surgical procedures to be done with minimally invasive instruments.

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

OBJECTIVES

To evaluate normative sonographic measurements of the inferior vena cava (IVC), aorta (Ao), and IVC/Ao ratio in the first 2 days of life in term neonates.

METHODS

We prospectively observed 200 term (more than 36 and 6/7 weeks of gestation), single, healthy neonates born in a city hospital. The exclusion criteria were congenital abnormalities, an Apgar score of less than 8, and hyperbilirubinemia requiring phototherapy. Maximum IVC (distal to the hepatic-IVC junction) and Ao (above the superior mesenteric artery) diameters were measured in the first 2 days of life in the longitudinal plane. Neonatal weight loss was calculated as a percentage lost from birth weight (BW).

RESULTS

A total of 200 (50% born vaginally, 53% male) neonates were enrolled. Correlations between IVC and aortic diameters as a function of gestational age, method of birth, weight loss, and body surface area (BSA) were calculated using the Spearman's rank correlation coefficient. The correlation coefficients were statistically significant for the IVC (P = .017) and Ao (P = .006) abdominal diameters versus gestational age. The Ao diameter correlated with BSA (P = .0001). In neonates with weight loss less than 8% of BW, the IVC/Ao ratio remained constant at 0.62 (95% confidence interval, 0.60-0.63).

CONCLUSIONS

Sonographic measurements of IVC and Ao maximum diameters in term neonates suggests a significant positive correlation among gestational age, BSA, and IVC and Ao diameters. The IVC/Ao ratios remain constant over 48 hours after birth in neonates with weight loss up to 8% of BW, and appear to be lower than previously reported ratios for healthy children.

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

Background

Evaluation of patient’s dry weight remains challenging in chronic hemodialysis (HD) especially in children. Inferior Vena Cava (IVC) measurement was reported useful to assess fluid overload both in adults and children.

Methods

We performed a monocentric prospective study to evaluate the relation between predialytic IVC diameter measurements and hydration status evaluated by physicians and bioimpedance spectroscopy (BIS) and between IVC measurements and persistent hypertension.

Results

Forty-eight HD sessions in 16 patients were analyzed. According to physicians, patients were overhydrated in 84.5% of dialysis sessions, 20.8% according to BIS, and 0%, 4.1% and 20.8% according to IVC inspiratory, expiratory and collapsibility index reference curves respectively. There was no correlation between relative overhydration evaluated by BIS and IVC measurements z-scores (p = 0.20). Patients whose blood pressure normalized after HD had a more dilated maximal IVC diameter before dialysis session than patients with persistent hypertension (median − 0.07SD [−0.8; 0.88] versus −1.61SD [−2.18; −0.74] (p = 0.03)) with an optimal cut-off of −0.5 SD.

Conclusions

In our study, IVC measurement is not reliable to assess fluid overload in children on HD and was not correlated with extracellular fluid volume assessed by BIS measurements. However, IVC measurements might be of interest in differentiating volume-dependant hypertension from volume-independant hypertension.

Electronic supplementary material

The online version of this article (10.1186/s12882-017-0793-1) contains supplementary material, which is available to authorized users.

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.

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

OBJECTIVES

To evaluate the correlation between echocardiographic inferior vena cava (IVC) measurements and central venous pressure (CVP) in neonates. Also, to evaluate the correlation between IVC measurements and gestational age (GA) and body weight (BW).

METHODS

This cross sectional analytical study was conducted from June 2014 through June 2016 in a level III NICU. All neonates requiring intensive hemodynamic monitoring and having umbilical venous catheter (UVC) in place for clinical indications were enrolled in the study. IVC measurements were recorded by echocardiography (ECHO) and CVP was measured concomitantly in neonates having appropriate sized UVC in place. IVC measurements were evaluated and compared for any correlation with the CVP, GA and BW.

RESULTS

Fifty neonates with median gestation of 37 wk [Q1 = 29.2, Q3 = 37.8, interquartile range (IQR) = 8.6 wk] and median birth weight of 2420 g (Q1 = 923.5, Q3 = 2850, IQR = 1926.5 g) were included in the study. A strong negative linear correlation was observed between IVC collapsibility index (IVC-CI) and CVP (r = -0.968, r² = -0.937, p 0.000). No correlation was observed between IVC-CI and GA or BW. IVC minimum and IVC maximum diameters did not correlate with CVP but correlated well with GA and BW.

CONCLUSIONS

Echocardiographic IVC-CI measurement has a good correlation with CVP measurement in neonates. The clinical use will depend on the ability of IVC-CI to predict surrogate markers of tissue perfusion in shock.

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.

Use of ultrasound by registered nurses-a systematic literature review

BACKGROUND

In Western Australia (WA), most stable patients undergoing haemodialysis receive treatment in a satellite setting where no doctors are on-site during treatment hours, so nurses must make critical decisions about fluid removal. Some patients regularly experience adverse events during dialysis (intradialytic), often due to excessive ultrafiltration goals, with intradialytic hypotension being particularly challenging. Ultrasound of the inferior vena cava has been previously demonstrated being a rapid and non-invasive method for volume assessment on haemodialysis patients, thus could hold valuable information for the treating nurse.

AIM

This paper examines the existing literature in regards to the use of ultrasound measurements of the inferior vena cava in patients on haemodialysis for objective assessment of their intravascular volume status by renal nurses.

METHOD

A systematic literature review was performed within medical and nursing databases including CINAHL Plus with Full Text, SCOPUS, Web of Science and MEDLINE.

RESULTS

Renal nurses are conscious of the significance of intradialytic hypotension and have only limited options for its prevention. Ultrasound of the inferior vena cava could add another objective dimension for intravascular volume assessment and prevention of intradialytic hypotension, but to date renal nurses have not been using this technique.

CONCLUSIONS

Ultrasound of the inferior vena cava has the potential to assist in defining the ultrafiltration goal for that particular dialysis session, thus reducing the risk of intradialytic hypotension. Additionally, it has potential to change current renal nursing practice when added to clinical nursing assessment methods. Further studies are required to validate this assessment tool carried out by a renal nurse compared with a skilled ultrasonographer.

Inferior Vena Cava Collapsibility Index is a Valuable and Non-Invasive Index for Elevated General Heart End-Diastolic Volume Index Estimation in Septic Shock Patients

Background

This study aimed to investigate the relationship between the inferior vena cava respirophasic variation (IVC collapsibility index [IVCCI]) and the general heart end-diastolic volume index (GEDVI). By determining the above relationship, we could evaluate the utility of IVCCI as an indicator.

Material/Methods

Forty-two septic patients were finally enrolled in this study. The inferior vena cava’s diameter was measured with the largest at the end of expiration (IVC3) and with the smallest at the end of inspiration (IVCi) on the ultrasound (IVCCI=[(IVCD e – IVCD i)/IVCD e] ×100%). The central venous pressure (CVP), cardiac index (CI), and GEDVI were also measured at least 3 times. After fluid resuscitation therapy, the patients with a CI increase induced by more than 15% and less than 15% were classified as the positive response group (PRG) and the negative response group (NRG), respectively.

Results

After treatment, the average levels of CVP, CI, and GEDVI were significantly higher (P<0.01) in both groups, whereas the IVCCI was reduced. CVP, CI, and GEDVI were negatively correlated with IVCCI in both groups. The correlation coefficient between IVCCI and GEDVI was the greatest (correlation coefficient in the PRG group was 0.889 and in the NRG group it was 0.672). The ROC curve analysis indicated that IVCCI illustrated the best area under the curve, with a sensitivity of 100% and specificity of 100%, and a cut-off value of 12.9% to predict GEDVI <600 ml/m² in the PRG group.

Conclusions

IVCCI was a good predictor of low-volume state. The IVCCI appears to be a valuable and non-invasive index for the estimation of elevated GEDVI during fluid resuscitation in septic shock patients.

Measurement of Central Venous Pressure Using Ultrasound in Emergency Department

Background:

In order to assessment of intravascular fluid measurement of central venous pressure (CVP) is used via central venous catheterization (CVC). This procedure is highly invasive and may cause serious complications such as pneumothorax, infection, hematoma and etc. It is so valuable procedure if we can uses a less invasive or noninvasive procedure to assess patients intravascular fluid in critical positions.

Objectives:

In this study, the ultrasound was used to measure the central venous pressure (CVP).

Patients and Methods:

In this study, patients with Central venous catheterization were selected using simple random sampling. The largest diameter of longitudinal, transverse views and the cross-section of inferior vena cava (IVC) and internal jugular vein (IJV) were measured using the ultrasound in the bedside of the patients. Central venous pressure was measured using routine methods. Correlations between variables were analyzed using SPSS and linear regression.

Results:

Twenty patients with the mean age of 60.3 were studied. The main reason for cardiac catheterization was shock. There are no relationship between anterior posterior diameter of inferior vena cava and CVP of patients (P = 0.257). The longest diameter of IVC in ultrasonographic transverse view had significant association with CVP of patients (P = 0.045) but in patients with BMI > 25 it was not significant. Cross section of internal jugular vein had significant association with CVP of patients (P = 0.003). Longitudinal diameter of internal jugular vein had no significant association with CVP of patients (P = 0.052), but transverse diameter of internal jugular generally had significant association with CVP of patients (P = 0.003). Cross section of internal jugular had significant association with CVP (P = 0.001).

Conclusions:

Noninvasive assessment of the patient hydration condition using the ultrasound is a simple and practicable measure in emergency. With regard to the considerations, it is possible to estimate CVP via diameter measurement and cross-section of the central veins.

Finding covert fluid: methods for detecting volume overload in children on dialysis

BACKGROUND

Lung ultrasound is a novel technique for detecting generalized fluid overload in children and adults with end-stage renal disease (ESRD). Echocardiography and bioimpedance spectroscopy are established methods, albeit variably adopted in clinical practice. We compared the practicality and accuracy of lung ultrasound with current objective techniques for detecting fluid overload in children with ESRD.

METHODS

A prospective observational study was performed to compare lung ultrasound B-lines, echocardiographic measurement of inferior vena cava parameters and bioimpedance spectroscopy in the assessment of fluid overload in children with ESRD on dialysis. The utility of each technique in predicting fluid overload, based on short-term weight gain, was assessed. Multiple linear regression models to predict fluid overload by weight were explored.

RESULTS

A total of 22 fluid assessments were performed in 13 children (8 on peritoneal dialysis, 5 on haemodialysis) with a median age of 4.0 (range 0.8-14.0) years. A significant linear correlation was observed between the number of B-lines detected by lung ultrasound and fluid overload by weight (r = 0.57, p = 0.005). A non-significant positive linear correlation was observed between fluid overload by weight and bioimpedance spectroscopy (r = 0.43, p = 0.2), systolic blood pressure (r = 0.19, p = 0.4) and physical examination measurements (r = 0.19, p = 0.4), while a non-significant negative linear relationship was found between the inferior vena cava collapsibility index and fluid overload by weight (r = -0.24, p = 0.3). In multiple linear regression models, a combination of three fluid parameters, namely lung ultrasound B-lines, clinical examination and systolic blood pressure, best predicted fluid overload (R ²  = 0.46, p = 0.05).

CONCLUSIONS

Lung ultrasound may be superior to echocardiographic methods and bioimpedance spectroscopy in detecting volume overload in children with ESRD. Given the practicality and sensitivity of this new technique, it can be adopted alongside clinical examination and blood pressure in the routine assessment of fluid status in children with ESRD.

Point-of-Care Ultrasound for Pediatric Shock

The evaluation of critically ill children in the emergency department is oftentimes challenging. Point-of-care ultrasound is an essential tool in the rapid identification of reversible pathology and provides unique insight into the appropriate treatment approach. In this article, we discuss a straightforward sonographic approach to pediatric patients who present in shock.

The baseline diameter of the inferior vena cava measured by sonography increases with age in normovolemic children

OBJECTIVES

To evaluate normative sonographic measurements of the inferior vena cava (IVC) diameter in healthy pediatric patients.

METHODS

We performed a prospective observational study of a convenience sample of healthy patients between the ages of 0 and 22 years presenting to a pediatric emergency department. Exclusion criteria included abnormal vital signs, pregnancy, or illnesses thought to influence volume status. During quiet respiration, the maximum and minimum IVC diameters were measured in the sagittal plane distal to the hepatic vein-IVC junction. As second measurements, the maximum diameters of the IVC and aorta were measured in the transverse plane distal to the insertion of the left renal vein into the IVC.

RESULTS

From February 2013 through April 2014, 63 children (51% female; mean age, 11 years) were enrolled. There were 20 children in each age group of 2 to 7, 7 to 12, and 12 to 22 years. The correlations between IVC and aortic diameters as a function of age were calculated using the Spearman rank correlation coefficient. The correlation coefficients were all statistically significant (P < .001): sagittal maximum IVC diameter (0.81), sagittal minimum IVC diameter (0.79), transverse maximum IVC diameter (0.79), and transverse maximum aortic diameter (0.81).

CONCLUSIONS

This pilot study of sonographic measurements of the IVC diameter in normovolemic children suggests a statistically significant positive correlation between age and IVC diameter. Future studies should focus on multicenter enrollment, children in the youngest age group, and the development of normative growth curves for the IVC by age, sex, and body mass index.

Bedside ultrasonographic measurement of the inferior vena cava fails to predict fluid responsiveness in the first 6 hours after cardiac surgery: a prospective case series observational study

OBJECTIVE

To assess validity of respiratory variation of inferior vena cava (IVC) diameter to predict fluid responsiveness and guide fluid therapy in mechanically ventilated patients during the first 6 hours after elective cardiac surgery.

DESIGN

Prospective observational case series study.

SETTING

Single-center hospital.

PATIENTS

50 consecutive patients undergoing elective cardiac surgery.

INTERVENTIONS

Transthoracic bedside echocardiography.

MEASUREMENTS AND MAIN RESULTS

Parameters derived from ultrasonographic assessment of the IVC diameter (collapsibility index [CI], distensibility index [DI], and IVC/aorta index). In the whole study group, change in fluid balance correlated with change in IVC maximum diameter (p = 0.034, r = 0.176). IVC-CI and IVC-DI correlated with IVC/aorta index. A weak correlation between central venous pressure (CVP) and IVC-derived parameters (IVC-CI and IVC-DI) was noticed. Despite statistical significance (p<0.05), all observed correlations expressed low statistical power (r<0.21). There were no statistically significant differences between fluid responders and nonresponders in relation to clinical parameters, CVP, ultrasound IVC measurement, and IVC-derived indices.

CONCLUSION

Dynamic IVC-derived parameters (IVC-CI, IVC-DI, and IVC/aorta index) and CVP are not reliable predictors of fluid responsiveness in the first 6 hours after cardiac surgery. Complexity of physiologic factors modulating cardiac performance in this group may be responsible for the difficulty in finding a plausible monitoring tool for fluid guidance. Bedside ultrasonographic measurement of IVC is unable to predict fluid responsiveness in the first 6 hours after cardiac surgery.

Sonographic assessment of the inferior vena cava/aorta index measured with the transducer placed in the anterior median line and right anterior axillary line - a comparison

The aim of the study was to compare the values of the sonographic inferior vena cava/ aorta index obtained with the transducer placed in the median line and right anterior axillary line.

Inferior vena cava/aorta diameter index in the assessment of the body fluid status - a comparative study of measurements performed by experienced and inexperienced examiners in a group of young adults

The assessment of the body fluid status is one the most challenging tasks in clinical practice. Although there are many methods to assess the body fluid status of patients, none of them is fully satisfactory in contemporary medical sciences. In the article below, we compare the results of measurements performed by experienced and inexperienced examiners based on the inferior vena cava/aorta diameter index in a sonographic hydration assessment. The study enrolled 50 young students at the age of 19-26 (the median age was 22.95) including 27 women and 23 men. The volunteers were examined in the supine position with GE Logiq 7 system and a convex transducer with the frequency of 2-5 MHz. The measurements were performed in the longitudinal and transverse planes by two inexperienced examiners - the authors of this paper, following a four-hour training conducted by an experienced sonographer. The longitudinal values of the inferior vena cava/aorta diameter index obtained in this study were similar to those found in the literature. The reference value for the inferior vena cava/aorta index determined by Kosiak et al., which constituted 1.2 ± 2 SD, for SD = 0.17, was similar to the values obtained by the authors of this paper which equaled 1.2286 ± 2 SD, for SD = 0.2. The article presented below proves that measuring the inferior vena cava/aorta diameter index is not a complex examination and it may be performed by physicians with no sonographic experience. Furthermore, the paper demonstrates that the inferior vena cava/aorta diameter index measured in the transverse plane is similar to the inferior vena cava/aorta diameter index determined in the longitudinal plane. Thus, both measurements may be used interchangeably to assess the hydration status of patients.

Lung ultrasonography for the assessment of rapid extravascular water variation: evidence from hemodialysis patients

Chest ultrasonography is a useful tool to assess extravascular lung water at bedside. In presence of interstitial-alveolar imbibition, vertical artifacts arising from the pleura are detected; these are called B-lines. Although a positive linear correlation between B-lines and extravascular lung water has been shown in symptomatic heart failure patients, the subclinical phase of pulmonary imbibition and the clearance of B-lines after rapid body fluid removal have been less investigated. The aim of this study was to assess if chest ultrasound could detect lung water imbibition and its variations induced by dialysis, an experimental model of controlled rapid fluid loss. Forty-one patients undergoing hemodialysis were studied. Total number of B-lines from ultrasound chest scanning and vena cava diameters were measured before and after treatment. Before dialysis, most of the patients presented ultrasound signs of pulmonary imbibition despite the absence of dyspnea; the number of B-lines was associated with the accumulated weight before treatment (p < 0.05) as well as with the residual weight after dialysis (p < 0.01); B-lines and end-inspiratory and end-expiratory vena cava diameters were also significantly reduced after dialysis. Moreover, B-lines reduction was significantly related to weight loss. Ultrasound performed at the bedside can detect lung water and intravascular overload and their reduction after dialysis in yet asymptomatic patients. These observations add further evidence regarding the use of lung ultrasound and inferior vena cava measurement in estimating volume overload and monitoring the response to therapy both in hemodialysis and congestive heart failure patients.

The diameter of the inferior vena cava provides a noninvasive way of calculating central venous pressure in neonates

AIM

To explore a less invasive way of assessing preload in neonates than fitting catheters to measure central venous pressure (CVP). This study evaluated the relationship between inferior vena cava (IVC) measurements and gestational age (GA) or body weight (BW) in term and premature infants and the correlation between those measurements and CVP in sick infants under mechanical ventilation.

METHODS

We studied 57 clinically stable infants, together with 14 sick infants fitted with central venous catheters to measure CVP. Subcostal transverse views were recorded at the level of the left branch of portal vein, and the minimum (DS ) and maximum (DL ) diameters of the IVC were measured. We evaluated the values of DS and DL and the S/L ratio (DS divided by DL ) in the clinically stable infants and the correlation between S/L and CVP in the sick infants with central catheters.

RESULTS

DS and DL correlated positively and strongly with both GA and BW, whereas S/L was almost independent of both GA and BW and correlated strongly with CVP.

CONCLUSION

At the subcostal transverse views, S/L is much less affected by either GA or BW than DS or DL and correlates strongly with CVP in mechanically ventilated infants.

Does bedside sonographic measurement of the inferior vena cava diameter correlate with central venous pressure in the assessment of intravascular volume in children?

OBJECTIVES

Previous studies demonstrated that the collapsibility index (percent decrease in inferior vena cava [IVC] diameter with inspiration) of 50% or greater and an IVC/aorta ratio of 0.8 or less correlated with a low intravascular volume. Our study sought to determine if bedside ultrasound (BUS) measurements of the IVC diameter correlate with central venous pressure (CVP) measurements as an indicator of intravascular volume status in acutely ill children.

METHODS

A convenience sample of children younger than 21 years who were admitted to the pediatric critical care unit and required CVP monitoring had BUS measurements of both IVC and aortic diameters with simultaneous CVP measurement. The collapsibility index (sagittal view) and IVC/aorta ratio (transverse view) were calculated from these measurements. A CVP of 8 mm Hg or less was considered as a marker for decreased intravascular volume.

RESULTS

Of the 51 participants, 21 (43%) had a CVP of 8 mm Hg or less. Eight (16%) of 51 children had a collapsibility index 50% or greater, and 8 (18%) of 43 had an IVC/aorta ratio of 0.8 or less. The sensitivity of a collapsibility index 0.5 or greater to predict a CVP of 8 mm Hg or less was 14%, the specificity was 83%, the positive predictive value was 38%, and the negative predictive value was 57%. Neither collapsibility index (r = -0.23, P = 0.11) nor IVC/aorta (r = -0.19, P = 0.22) correlated with CVP in assessing intravascular volume in our study population.

CONCLUSIONS

Based on these data, the IVC and aortic measurements by BUS are not reliable indicators of intravascular volume (as determined by CVP) in acutely ill children.

Resuscitation of the pregnant patient: What is the effect of patient positioning on inferior vena cava diameter?

STUDY OBJECTIVE

Patients in the third trimester of pregnancy presenting to the emergency department (ED) with hypotension are routinely placed in the left lateral tilt (LLT) position to relieve inferior vena cava (IVC) compression from the gravid uterus thereby increasing venous return. However, the relationship between patient position and proximal intrahepatic IVC filling has never assessed directly. This study set out to determine the effect of LLT position on intrahepatic IVC diameter in third trimester patients under real-time visualization with ultrasound.

METHODS

This prospective observational study on the labor and delivery floor of a large urban academic teaching hospital enrolled patients between 30 and 42 weeks estimated gestational age from August 2011 to March 2012. Patients were placed in three different positions: supine, LLT, and right lateral tilt (RLT). After the patient was in each position for at least 3 min, IVC ultrasound using the intercostal window was performed by one of three study sonologists. Maternal and fetal hemodynamics were also monitored and recorded in each position.

RESULTS

A total of 26 patients were enrolled with one excluded from data analysis due to inability to obtain IVC measurements. The median IVC maximum diameter was 1.26 cm (95% confidence interval [CI] 1.13-1.55) in LLT compared to 1.13 cm (95% CI 0.89-1.41) in supine, p=0.01. When comparing each individual patient's LLT to supine measurement, LLT lead to an increase in maximum IVC diameter in 76% (19/25) of patients with the average LLT measurement 29% (95% confidence interval 10-48%) larger. Six patients had the largest maximum IVC measurement in the supine position. No patients experienced any hemodynamic instability or distress during the study.

CONCLUSION

IVC ultrasound is feasible in late pregnancy and demonstrates an increase in diameter with LLT positioning. However, a quarter of patients had a decrease in IVC diameter with tilting and, instead, had the largest IVC diameter in the supine position suggesting that uterine compression of the IVC may not occur universally. IVC assessment at the bedside may be a useful adjunct in determining optimal positioning for resuscitation of third trimester patients.

Caval Aorta Index and Central Venous Pressure Correlation in Assessing Fluid Status! “Ultrasound Bridging the Gap”

Accurate body fluid assessment and estimation of fluid status are essential in guiding fluid therapy in emergency setup. This prospective cross-sectional descriptive study conducted to ascertain the effectiveness of inferior vena cava and aorta (IVC/Aorta) index in assessing the fluid status by comparing it with the central venous pressure (CVP). Results showed the mean IVC/Aorta index in patients who had normal CVP range was 1.2 ± 0.12 SD, while in patients with low CVP, the mean index was 0.7 ± 0.09 SD, and, patients with high CVP, the mean index was 1.6 ± 0.05 SD. In conclusion, the sonographic IVC/Aorta index assessment seems to be a quick, simple, noninvasive, and reliable method to access the fluid status in a busy setup like an emergency room.

Correlation of internal jugular vein/common carotid artery ratio to central venous pressure: a pilot study in pediatric burn patients

The purpose of this pilot study was to identify the relationship between the ratio of the diameter/cross-sectional area of the internal jugular vein (IJV) and carotid artery and the central venous pressure (CVP). After obtaining approval from our Institutional Review Board, ultrasound images were repeatedly obtained from participants on consecutive days when a thoracic central line was in place. The CVP was then measured in standardized fashion, using our bedside monitors. A blinded observer measured the diameter of the common carotid artery and IJV, for comparison. Similarly, digital images were analyzed to compare an estimate of the cross-sectional areas of the same vessels. Six patients met enrollment criteria, and one patient was excluded after enrollment before any measurements being made. The remaining five patients had a mean age of 7 years (range: 9 months to 15 years) and mean burn size of 64% (SD, ±15), and no patients had inhalation injuries. All patients in this study were mechanically ventilated. Measurements were made from one patient while spontaneously breathing. One patient reading occurred while on vasopressor support (levophed at 2 μg/kg/hr). CVP values ranged from 1 to 25 mm Hg. Comparison of the ratio of the IJV/common carotid artery cross-sectional area with CVP revealed that a ratio of 2 or greater was associated with a CVP of at least 8 mm Hg (P < .001). These preliminary results suggest that if the cross-sectional area of the vein is at least twice that of the artery, then the CVP seems to be ≥8 mm Hg.

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.

Emergency echocardiography

Emergency echocardiography refers to the use of cardiac ultrasound to address critical and time-sensitive clinical questions during the initial evaluation and treatment of the critically ill patient presenting to the emergency department. The information obtained can be pivotal to a physician's clinical decision making and can guide further diagnostic or therapeutic interventions. This article provides an evidence-based discussion of the common uses of emergency transthoracic echocardiography, as well as its benefits and limitations in the current practice of emergency medicine.

Comparison of serial qualitative and quantitative assessments of caval index and left ventricular systolic function during early fluid resuscitation of hypotensive emergency department patients

OBJECTIVES

The objective was to determine whether serial bedside visual estimates of left ventricular systolic function (LVF) and respiratory variation of the inferior vena cava (IVC) diameter would agree with quantitative measurements of LVF and caval index in hypotensive emergency department (ED) patients during fluid challenges. The authors hypothesized that there would be moderate inter-rater agreement on the visual estimates.

METHODS

This prospective observational study was performed at an urban, regional ED. Patients were eligible for enrollment if they were hypotensive in the ED as defined by a systolic blood pressure (sBP) of <100 mm Hg or mean arterial pressure of ≤65 mm Hg, exhibited signs or symptoms of shock, and the treating physician intended to administer intravenous (IV) fluid boluses for resuscitation. Sonologists performed a sequence of echocardiographic assessments at the beginning, during, and toward the end of fluid challenge. Both caval index and LVF were determined by the sonologist in qualitative then quantitative manners. Deidentified digital video clips of two-dimensional IVC and LVF assessments were later presented, in random order, to an ultrasound (US) fellowship-trained emergency physician using a standardized rating system for review. Statistical analysis included both descriptive statistics and correlation analysis.

RESULTS

Twenty-four patients were enrolled and yielded 72 caval index and LVF videos that were scored at the bedside prior to any measurements and then reviewed later. Visual estimates of caval index compared to measured caval index yielded a correlation of 0.81 (p < 0.0001). Visual estimates of LVF compared to fractional shortening yielded a correlation of 0.84 (p < 0.0001). Inter-rater agreement of respiratory variation of IVC diameter and LVF scores had simple kappa values of 0.70 (95% confidence interval [CI] = 0.56 to 0.85) and 0.46 (95% CI = 0.29 to 0.63), respectively. Significant differences in mean values between time 0 and time 2 were found for caval index measurements, the visual scores of IVC diameter variation, and both maximum and minimum IVC diameters.

CONCLUSIONS

This study showed that serial visual estimations of the respiratory variation of IVC diameter and LVF agreed with bedside measurements of caval index and LVF during early fluid challenges to symptomatic hypotensive ED patients. There was moderate inter-rater agreement in both visual estimates. In addition, acute volume loading was associated with detectable acute changes in IVC measurements.