Inferior Vena Cava Parameters Research Articles

Assessment of volume status of pediatric hemodialysis patients.

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. 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. A total 60 children (mean age 9.4 ± 2.8years) 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. 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.

Correlation of Baseline Inferior Vena Cava Diameter and Collapsibility with Age and Sex in Normovolaemic Children: A Cross-sectional Study

Introduction: Ultrasound measurement of Inferior Vena Cava (IVC) diameter and collapsibility is increasingly used for volume status assessment and fluid responsiveness in paediatric and adult population. There is a wide variation in the age specific IVC diameters in paediatric population, whereas age specific variation in IVC collapsibility in euvolaemic children is not much known. Aim: To analyse the correlation of baseline IVC diameter and collapsibility with age and sex in euvolaemic children. Materials and Methods: This cross-sectional study was conducted at Kerala Institute of Medical Sciences, a tertiary care hospital in south Kerala, India, over a study period from June 2014 to May 2016. A total of 80 children in the age group of one month to 15 years, who presented without evidence of volume depletion were enrolled. The IVC was assessed approximately 2 cm distal to IVC-hepatic vein junction, Motion mode (M-mode) measurement of maximum (expiratory) and minimum (inspiratory) width of IVC diameter was measured. Collapsibility Index was also calculated for each subject by measuring difference between the maximum and minimum IVC diameters divided by the maximum diameter. The statistical data was analysed using the statistical software Statistical Package for Social Sciences (SPSS) version 16. All the numerical data was expressed as mean±Standard Deviation (SD). Quantitative analysis was performed using Analysis of Variance (ANOVA) and t-test. The correlation of IVC parameters were assessed using Karl Pearson correlation coefficient. The p-value less than 0.05 was considered as significant. Results: Eighty euvolaemic children between the age one month and 15 years were enrolled in the study. The mean age of study group was 5±4 years. Males 41 (51.3%) and females 39 (48.8%) were almost equally distributed. A significant strong positive correlation was found between IVC expiratory and inspiratory diameter with age using Karl Pearson correlation, r= 0.912, p<0.001; r=0.876, p<0.001, respectively. No significant correlation was found between IVC collapsibility and age, Karl Pearson correlation, r=0.079, p=0.485. No correlation was found between sex and the IVC parameters. Conclusion: According to the present study results, IVC diameter showed a positive correlation with age but not with sex. The IVC collapsibility had no correlation with either age or sex.

Correlation of preoperative inferior vena cava diameter and inferior vena cava collapsibility index with preoperative fasting status, patient demography and general anaesthesia associated hypotension: A prospective, observational study.

A definitive cutoff of inferior venacava (IVC) diameter in expiration (dIVCmax) and inferior vena cava collapsibility index (IVCCI) for predicting general anaesthesia associated hypotension (GAAH) is not yet determined. Primary objective of this study was to determine the correlation of dIVCmax and IVCCI, with GAAH. Other objectives were to determine the correlation of these IVC parameters with preoperative fasting duration, temperature and humidity. The correlation of dIVCmax with patient demography was also studied. A total of 110 adult patients undergoing elective surgery under general anaesthesia were included in the study. IVC ultrasonography was done in the preoperative room, 20 to 30 minutes before shifting the patient to the operating room. Hypotension at (hypo@) 2 minutes and 10 minutes after administering vecuronium was recorded. Hundred and seven patients were analysed. A significant positive correlation was present between patient height and dIVCmax (r = 0.25, P = 0.009). Area under receiver operating characteristics curve was 0.595 (95% confidence interval (CI) 0.485-0.705) and 0.568 (95% CI 0.458-0.679) for dIVCmax and IVCCI for predicting hypo@2 min, with a diagnostic accuracy of 54% and 53%, respectively. dIVCmax ≤1.14 cm had a sensitivity of 31% and specificity of 87% in predicting GAAH. IVCCI ≥63.3% could predict GAAH with 31% sensitivity and 84% specificity. No significant correlation was found between preoperative IVC parameters and preoperative fasting or environmental factors. Both dIVCmax and IVCCI have poor diagnostic accuracy, with good specificity and low sensitivity in predicting GAAH. A steady formula for calculating baseline IVC diameter adjusted for patient demography is needed.

Role of non-invasive imaging in budd-chiari syndrome

Background and Objectives: Symptoms of Budd-Chiari syndrome (BCS) are often nonspecific or even absent; as a result radiographic imaging plays a critical role in diagnosis. The diagnosis is profoundly dependent on modern radiological imaging techniques, depending on the detection of thrombosis and/or stenosis of hepatic veins or the upper portion of the inferior vena cava. This study was hence conducted to evaluate the role of imaging in BCS.Materials and Methods: This prospective study was conducted in 40 patients diagnosed with BCS over a period of three years. Patients with history of frequent abdominal pain, ascites, hepatomegaly, fever, hepatic encephalopathy and variceal bleeding were included. All patients underwent imaging tests like ultrasonography, or computed tomography scan, and magnetic resonance imaging (MRI). Results: A total of 40 patients, with an average age of 35.13 ± 15.19 years, were included in our study. There was no significant difference in the size of liver and size of spleen estimated by the imaging techniques; however, the type of liver margin was better identified by the MRI. There was no significant difference in the caudate lobe-to-right lobe ratio, distribution of enhancement patterns, intrahepatic collaterals, inferior vena cava parameters, and ultrasonography spectral findings of the three hepatic veins between the modalities.MR venography was found to be better at identifying the different patterns in the right, middle and left hepatic veins.Conclusions: Not only does MRI identify BCS stages and potential complications, these findings are diagnosed with an added advantage of no radiation exposure and reproducibility of findings.

Clinical Utility of Superior Vena Cava Flow Velocity Waveform Measured from the Subcostal Window for Estimating Right Atrial Pressure

The superior vena cava (SVC) flow velocity waveform from the supraclavicular window reflects right atrial pressure (RAP) status. Recent guidelines have stated that the subcostal window is an alternative view for recording SVC flow, but the validity of this approach remains unclear. The aim of this study was to determine the usefulness of SVC flow evaluation from the subcostal window for estimating RAP. Differences in SVC flow characteristics between opposite approaches were examined in 38 healthy adults. In 115 patients with cardiovascular diseases who underwent cardiac catheterization and echocardiography within 48hours, the ratio of peak systolic to diastolic forward SVC flow (SVC-S/D) was measured, and the diagnostic ability of SVC-S/D for elevated RAP was tested. A validation cohort was used to confirm the diagnostic ability of SVC-S/D in 48 patients who underwent both cardiac catheterization and echocardiography within 24hours. In 59 patients in the derivation and validation cohorts, the relationship between SVC flow and RAP was compared between the opposite windows. Both systolic and diastolic SVC flow velocities were higher in the subcostal than in the supraclavicular approach, and effect of position change on subcostal SVC-S/D was smaller than that on supraclavicular SVC-S/D in healthy adults. Measurement of SVC-S/D from the subcostal window was feasible in 98 patients (85%). RAP was inversely correlated with SVC-S/D (r=-0.50, P<.001) and was an independent determinant of SVC-S/D after adjustment for right ventricular systolic function (β=-0.48, P<.001). A cutoff value of 1.9 for SVC-S/D showed 85% sensitivity and 74% specificity in identifying elevated RAP. Additionally, SVC-S/D showed an incremental diagnostic value combined with inferior vena cava size and collapsibility (P=.006). When a cutoff value of SVC-S/D<1.9 was applied to the validation cohort, it showed acceptable accuracy of 72% and incremental diagnostic value combined with inferior vena cava parameters (P=.033). SVC-S/D from the subcostal window correlated better with RAP than that from the supraclavicular window (P<.001, Meng's test). Measurement of SVC flow velocity from the subcostal window was feasible, and SVC-S/D from the subcostal window could be an additive parameter for estimating RAP.

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 &lt; 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 &lt; 0.005). The significantly lower values of NT-proBNP in all groups (p &lt; 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.

Prediction of post-induction hypotension in young adults using ultrasound-derived inferior vena cava parameters: An observational study.

Background and Aims:Inferior vena cava (IVC) diameter and its respiratory variability have been shown to predict post-induction hypotension with high specificity in a mixed population of patients. We assessed whether these parameters could be as reliable in healthy adult patients as in a mixed patient population.Methods:In the present prospective observational study, 110 patients of either sex, aged between 18 and 50 years, belonging to American Society of Anesthesiologists class I and II, fasted as per the institutional protocol and scheduled for elective surgery under general anaesthesia were enroled. Prior to induction, ultrasound examination of IVC was done and variation in IVC diameter with respiration was assessed. Maximum and minimum IVC diameters [(dIVCmax) and (dIVCmin), respectively] over a single respiratory cycle were measured and collapsibility index (CI) was calculated. Vitals were recorded just before induction and at every minute after induction for 10 min. Episodes of hypotension (mean arterial pressure [MAP] <65 mmHg or fall in MAP >30% from baseline) during the observation period were recorded. The receiver operating characteristic (ROC) curve was constructed for determining optimum cut-off with sensitivity and specificity of IVC diameters and CI for development of hypotension.Results:IVC was not visualised in 22 patients. Out of the remaining 88 patients, 17 (19.3%) patients developed hypotension after induction. The dIVCmax, dIVCmin and CI were comparable between patients who developed and who did not develop hypotension. The area under curve of ROC for CI, dIVCmax and dIVCmin was 0.51, 0.55 and 0.52, respectively, with optimum cut-off value of 0.46, 1.42 and 0.73, respectively.Conclusion:Ultrasound-derived IVC parameters demonstrate poor diagnostic accuracy for prediction of hypotension after induction in healthy adult patients.

Role of Inferior Vena Cava Parameters as Predictors of Fluid Responsiveness in Pediatric Septic Shock: A Prospective Study

AbstractFluid resuscitation is the initial therapy for septic shock worldwide. Prediction of fluid responsiveness is essential for optimizing fluid administration. Only few pediatric studies have evaluated the role of inferior vena cava (IVC) as a reliable predictor of fluid responsiveness. The aim of this study was to evaluate the role of IVC parameters as predictors of fluid responsiveness in children (under the age of 5 years) having septic shock at different times from admission. A prospective observational study included 51 children having septic shock. It was conducted in the nine-bedded pediatric intensive care unit of a university hospital from January 1, 2018, to the August 31, 2018. Echocardiography was used to assess minimal and maximal IVC diameters and its distensibility index with simultaneous assessment of stroke volume (SV), at 1, 6, and 24 hours from admission. The decision to give fluid in these children was thereby based on the presence of at least one sign of inadequate tissue perfusion. SV was reassessed directly after administration of a fluid bolus of 10 mL/kg over 10 minutes. Fluid responsiveness was considered adequate when there was ≥ 10% increase in SV after fluid bolus. Minimal IVC diameter indexed to body surface area and its distensibility index can be predictors of fluid responsiveness at all times: 1 hour (area under curve [AUC] = 0.88; 95% confidence interval [CI] = 0.77–0.96), 6 hours (AUC = 0.86; 95% CI = 0.67–0.97), and 24 hours (AUC = 0.77; 95% CI = 0.6–0.95). IVC distensibility index can also predict fluid responsiveness at 1 hour (AUC= 0.87; 95% CI = 0.74–0.95), 6 hours (AUC = 0.86; 95% CI = 0.73–0.94), and 24 hours (AUC = 1; 95% CI = 0.77–1). The cutoff points of each parameter differed from time to time (contradicts with previous statement that says it is predictor at all times). The maximum IVC diameter could not predict fluid responsiveness at any time from admission. Minimal IVC diameter and its distensibility index were feasible noninvasive surrogates of fluid responsiveness in pediatric septic shock at different times from admission.

SUN-081 USE OF HANDHELD ULTRASOUND TO ESTIMATE FLUID STATUS OF HEMODIALYSIS PATIENTS

Accurate assessment of fluid status in hemodialysis patients presents a significant challenge. Nephrologists have long relied on dry weight estimation based solely on clinical parameters to decide the ultrafiltration volume for patients with end-stage kidney disease on dialysis. However, this method is far from accurate and many patients recurrently suffer from signs and symptoms of fluid overload or circulatory collapse from overaggressive ultrafiltration. Invasive methods such as measurement of central venous pressure cannot be used routinely. We evaluated the usefulness of inferior vena cava (IVC) diameter measured by handheld ultrasound in the estimation of fluid status in patients before and after hemodialysis. Clinical assessment included patients’ symptoms, weight, blood pressure, heart rate, and presence of edema before and after dialysis session. Dry weight was assessed based on the above parameters. Each patient underwent measurement of inferior vena cava before and after hemodialysis. The anteroposterior IVC diameter (IVCD) was measured 1.5 cm below the diaphragm in the hepatic segment in supine position during normal inspiration and expiration. Thirty hemodialysis patients (mean age 51.6±18.03 years) were evaluated in outpatient dialysis unit. Following hemodialysis mean IVCe (IVC diameter in expiration) decreased from 1.40±0.38 to 0.91±0.30 cm (p<0.001). Similarly, mean IVCi (IVC diameter in inspiration) decreased from 0.67±0.34 to 0.35±0.19 cm (p<0.001). Changes in IVCD were significantly correlated with alterations in body weight following dialysis (p<0.0001). The IVC collapsibility index (IVC-CI, per cent of change in IVC diameter in expiration vs. inspiration) increased significantly from 0.53±0.18 to 0.68±0.18 after dialysis (p=0.002). IVC diameter and IVC-CI clearly reflected alterations in fluid status. Regarding the clinical parameters of fluid status, following hemodialysis, mean heart rate increased from 81.17±5.21 beats per minute to 86.50±7.99, (p=0.003), systolic blood pressure increased from 148.67±26.36 mmHg to 155.00±28.50, (p=0.05), and diastolic blood pressure increased from 78.62±12.74 mmHg to 84.83±14.55, (p<0.001). Our findings support the applicability of IVCD measurement and IVC-CI in the estimation of fluid status in end stage kidney disease patients on hemodialysis. The clinical parameters of fluid status including heart rate, systolic blood pressure, and diastolic blood pressure suggest that significant numbers of patients underwent excess ultrafiltration based on their traditional dry weight calculation. Thus, using IVC parameters before and during hemodialysis might give a better estimation of fluid status of the patient and guide the amount of ultrafiltration to be done.

Diagnosis of Acute Heart Failure Using Inferior Vena Cava Ultrasound: Systematic Review and Meta-analysis.

The utility of bedside inferior vena cava (IVC) ultrasound (US) in the diagnosis of heart failure (HF) is unclear. The aim of this study was to determine whether IVC parameters in patients with acute heart failure (AHF) are statistically different from those without HF. The MEDLINE database of English-language publications from 1966 to August 2018 was searched. Retrospective and prospective studies that included either IVC expiratory diameter (IVCexp ) or IVC collapsibility index (IVC-CI) values were collected in patients with and without HF. to determine whether there was a statistical difference in the IVC parameters between these groups. A total of 27 articles with a total of 1472 patients with AHF were included. The standard mean differences for the IVCexp and IVC-CI for the control group versus the AHF group were found to be statistically significant (P < .0001). The combined mean IVCexp values were 15.11 mm (95% confidence interval [CI], 14.19-16.02 mm) for the control group and 20.26 mm (95% CI, 14.82-25.71 mm) for the AHF group. The combined mean IVC-CI values were 61.6% (95% CI, 48.4%-74.7%) for the control group and 30.5% (95% CI, 26.4%-34.6%) for the AHF group. Bedside IVC US showed that a statistically significant difference existed in the IVC parameters between patients with and without AHF. Based on mean calculations, an IVCexp of greater than 2.0 cm and an IVC-CI of less than 30% are reasonable cutoffs to suggest that a patient with acute dyspnea is more likely to have AHF than a non-AHF condition. Given the high degree of heterogeneity across the studies and the high risk of bias, larger randomized studies are warranted to explore the use of IVC US in patients with HF.

The Value of the Inferior Vena Cava Area Distensibility Index and its Diameter Ratio for Predicting Fluid Responsiveness in Mechanically Ventilated Patients.

It is necessary to evaluate fluid responsiveness before fluid resuscitation. We evaluated the value of inferior vena cava (IVC) area respiratory variation and the IVC diameter ratio (IVC DR) for predicting fluid responsiveness in mechanically ventilated patients. A prospective observational study was performed in the intensive care unit between December 2017 and March 2018. Mechanically ventilated patients were enrolled and received ultrasound monitoring. IVC diameter distensibility index from the subxiphoid area (IVC-sx DDI), IVC diameter distensibility index from the right midaxillary line (IVC-rm DDI), IVC area distensibility index (IVC ADI), and IVC DR in cross-section were calculated by ultrasound monitoring IVC parameters. The enrolled patients were classified as nonresponders group and responders group according to whether the cardiac output increased by >10% after passive leg raising. Data from 67 mechanically ventilated patients were analyzed. 55.2% of patients had positive fluid responsiveness. The area of receiver operating characteristic curves evaluating the ability of the IVC-sx DDI, IVC-rm DDI, IVC ADI, and IVC DR to predict the fluid responsiveness were 0.702, 0.686, 0.749, and 0.829, respectively. IVC DR level of 1.43 was predictive of positive fluid responsiveness with 90.0% specificity and 67.6% sensitivity. IVC ADI level of 10.2% was predictive of positive fluid responsiveness with 40.0% specificity and 97.3% sensitivity. IVC ADI and its diameter ratio in cross-section had more value than IVC diameter distensibility index for predicting fluid responsiveness in mechanically ventilated patients.

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

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

Use of Handheld Ultrasound to Estimate Fluid Status of Hemodialysis Patients

Introduction: Accurate assessment of fluid status in hemodialysis patients presents a significant challenge. Nephrologists have long relied on dry weight estimation based solely on clinical parameters to decide the ultrafiltration volume for patients with end-stage kidney disease on dialysis. However, this method is far from accurate and many patients recurrently suffer from signs and symptoms of fluid overload or circulatory collapse from overaggressive ultrafiltration. Invasive methods such as measurement of central venous pressure cannot be used routinely. We evaluated the usefulness of inferior vena cava (IVC) diameter measured by handheld ultrasound in the estimation of fluid status in patients before and after hemodialysis. Materials and Methods: Clinical assessment included patients’ symptoms, weight, blood pressure, heart rate, and presence of edema before and after dialysis session. Dry weight was assessed based on the above parameters. Each patient underwent measurement of inferior vena cava before and after hemodialysis. The anteroposterior IVC diameter (IVCD) was measured 1.5 cm below the diaphragm in the hepatic segment in supine position during normal inspiration and expiration.Results: Thirty hemodialysis patients (mean age 51.6±18.03 years) were evaluated in outpatient dialysis unit. Following hemodialysis mean IVCe (IVC diameter in expiration) decreased from 1.40±0.38 to 0.91±0.30 cm (p&lt;0.001). Similarly, mean IVCi (IVC diameter in inspiration) decreased from 0.67±0.34 to 0.35±0.19 cm (p&lt;0.001). Changes in IVCD were significantly correlated with alterations in body weight following dialysis (p&lt;0.0001). The IVC collapsibility index (IVC-CI, per cent of change in IVC diameter in expiration vs. inspiration) increased significantly from 0.53±0.18 to 0.68±0.18 after dialysis (p=0.002). IVC diameter and IVC-CI clearly reflected alterations in fluid status. Regarding the clinical parameters of fluid status, following hemodialysis, mean heart rate increased from 81.17±5.21 beats per minute to 86.50±7.99, (p=0.003), systolic blood pressure increased from 148.67±26.36 mmHg to 155.00±28.50, (p=0.05), and diastolic blood pressure increased from 78.62±12.74 mmHg to 84.83±14.55, (p&lt;0.001).Conclusions: Our findings support the applicability of IVCD measurement and IVC-CI in the estimation of fluid status in end stage kidney disease patients on hemodialysis. The clinical parameters of fluid status including heart rate, systolic blood pressure, and diastolic blood pressure suggest that significant numbers of patients underwent excess ultrafiltration based on their traditional dry weight calculation. Thus, using IVC parameters before and during hemodialysis might give a better estimation of fluid status of the patient and guide the amount of ultrafiltration to be done.

Handheld Ultrasound as a Novel Predictive Tool in Atrial Fibrillation: Prediction of Outcomes Following Electrical Cardioversion.

BackgroundAtrial fibrillation (AF) recurrence after successful direct current cardioversion (CV) is common, and clinical predictors may be useful. We evaluated the risk of early AF recurrence according to inferior vena cava (IVC) measurements by handheld ultrasound (HHU) at the time of CV.ObjectiveAssess HHU and objectively obtained measurements acquired at the point of care as potential clinical predictors of future clinical outcomes in patients with AF undergoing CV.MethodsMaximum IVC diameter (IVCd) and collapsibility with inspiration were measured by the Vscan HHU (General Electric Healthcare Division) in 128 patients immediately before and after successful CV for AF. Patients were followed by chart review for recurrence of AF.ResultsMean IVCd was 2.16 cm in AF pre-CV and 2.01 cm in sinus rhythm post-CV (P<.001). AF recurred within 30 days of CV in 34 of 128 patients (26.6%). Among patients with IVCd <2.1 cm pre-CV and decrease in IVCd post-CV, AF recurrence was 12.1%, compared to 31.6% in patients not meeting these parameters (odds ratio [OR] 0.299, P=.04). This association persisted after adjustment for age, ejection fraction <50%, left atrial enlargement, and amiodarone use (adjusted OR 0.185, P=.01). Among patients with IVCd post-CV <1.7 cm, AF recurrence was 13.5%, compared to 31.9% in patients not meeting this parameter (OR 0.185, P=.01). IVC parameters did not predict AF recurrence at 180 or 365 days.ConclusionsThe presence of a normal IVCd pre-CV that becomes smaller post-CV and the presence of a small IVCd post-CV were each independently associated with reduced likelihood of early, but not late, AF recurrence. HHU assessment of IVCd at the time of CV may be useful to identify patients at low risk of early recurrence of AF after CV.

Focused cardiac ultrasound as a predictor of readmission in acute decompensated heart failure.

Acute decompensated heart failure (ADHF) is a common reason for admission to the hospital, and readmission is frequent. Multiple factors contribute to rehospitalizations, but inadequate assessment of volume status leading to persistent congestion is an important factor. We sought to determine if focused cardiac ultrasound (FCU) of the inferior vena cava (IVC), as a surrogate of volume status, would predict readmission of ADHF patients after index hospitalization. Patients admitted with a primary diagnosis of ADHF were prospectively enrolled. All patients underwent FCU of the IVC on admission and then daily. 82 patients were enrolled. Patients demonstrated improvement in heart failure physical examination findings and symptoms during the hospitalization. There was a reduction in the size of the IVC and a significant increase in patients with small collapsible vena cava. Logistic regression analysis of physical examination, patient symptoms, and IVC parameters at discharge demonstrated IVC collapsibility and patient reported dyspnea improvement as the only significant variables to predict readmission or emergency department visit. FCU assessment of IVC size and collapsibility may be useful in patients with ADHF to predict risk of being readmitted within 30days of hospital discharge.

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

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

Dynamic Measurement of Hemodynamic Parameters and Cardiac Preload in Adults with Dengue: A Prospective Observational Study.

Few previous studies have monitored hemodynamic parameters to determine the physiological process of dengue or examined inferior vena cava (IVC) parameters to assess cardiac preload during the clinical phase of dengue. From January 2013 to July 2015, we prospectively studied 162 hospitalized adults with confirmed dengue viral infection using non-invasive cardiac output monitoring and bedside ultrasonography to determine changes in hemodynamic and IVC parameters and identify the types of circulatory shock that occur in patients with dengue. Of 162 patients with dengue, 17 (10.5%) experienced dengue shock and 145 (89.5%) did not. In patients with shock, the mean arterial pressure was significantly lower on day 6 after fever onset (P = 0.045) and the pulse pressure was significantly lower between days 4 and 7 (P<0.05). The stroke volume index and cardiac index were significantly decreased between days 4 and 15 and between days 5 and 8 after fever onset (P<0.05), respectively. A significant proportion of patients with dengue shock had an IVC diameter <1.5 cm and IVC collapsibility index >50% between days 4 and 5 (P<0.05). Hypovolemic shock was observed in 9 (52.9%) patients and cardiogenic shock in 8 (47.1%), with a median (interquartile range) time to shock onset of 6.0 (5.0–6.5) days after fever onset, which was the median day of defervescence. Intravascular hypovolemia occurred before defervescence, whereas myocardial dysfunction occurred on the day of defervescence until 2 weeks after fever onset. Hypovolemic shock and cardiogenic shock each occurred in approximately half of the patients with dengue shock. Therefore, dynamic measures to estimate changes in hemodynamic parameters and preload should be monitored to ensure adequate fluid therapy among patients with dengue, particularly patients with dengue shock.

Effect of Inhalational Anesthetics and Positive-pressure Ventilation on Ultrasound Assessment of the Great Vessels: A Prospective Study at a Children's Hospital.

Bedside ultrasound has emerged as a rapid, noninvasive tool for assessment and monitoring of fluid status in children. The inferior vena cava (IVC) varies in size with changes in blood volume and intrathoracic pressure, but the magnitude of change to the IVC with inhalational anesthetic and positive-pressure ventilation (PPV) is unknown. Prospective observational study of 24 healthy children aged 1 to 12 yr scheduled for elective surgery. Ultrasound images of the IVC and aorta were recorded at five time points: awake; spontaneous ventilation with sevoflurane by mask; intubated with peak inspiratory pressure/positive end-expiratory pressure of 15/0, 20/5, and 25/10 cm H2O. A blinded investigator measured IVC/aorta ratios (IVC/Ao) and changes in IVC diameter due to respiratory variation (IVC-RV) from the recorded videos. Inhalational anesthetic decreased IVC/Ao (1.1 ± 0.3 vs. 0.6 ± 0.2; P < 0.001) but did not change IVC-RV (median, 43%; interquartile range [IQR], 36 to 58% vs. 46%; IQR, 36 to 66%; P > 0.99). The initiation of PPV increased IVC/Ao (0.64 ± 0.21 vs. 1.16 ± 0.27; P < 0.001) and decreased IVC-RV (median, 46%; IQR, 36 to 66% vs. 9%; IQR, 4 to 14%; P < 0.001). There was no change in either IVC/Ao or IVC-RV with subsequent incremental increases in peak inspiratory pressure/positive end-expiratory pressure (P > 0.99 for both). Addition of inhalational anesthetic affects IVC/Ao but not IVC-RV, and significant changes in IVC/Ao and IVC-RV occur with initiation of PPV in healthy children. Clinicians should be aware of these expected vascular changes when managing patients. Establishing these IVC parameters will enable future studies to better evaluate these measurements as tools for diagnosing hypovolemia or predicting fluid responsiveness.

THE UTILITY OF BEDSIDE CLINICAL ASSESSMENT OF INTRAVASCULAR VOLUME STATUS WITH HAND CARRIED ULTRASOUND DEVICES IN HEMODIALYSIS CLINICS

In Canada, the majority of end stage renal disease (ESRD) patients undergo conventional facility based hemodialysis. Despite technological advancements, conventional hemodialysis is associated with significant patient morbidity and mortality related to fluid imbalances. Inaccurate hemodialysis prescriptions calculated from clinical estimates of intravascular volume status (IVS) may serve as a major contributor to patient morbidity. Previous studies have demonstrated improved patient outcomes by adjusting hemodialysis prescriptions based on echocardiographic volume assessments. However, implementation of this platform in practice remains impractical, warranting further research in order to assess whether Hand-Carried Ultrasound (HCU) provides similar benefits in chronic hemodialysis patients. The primary objective of this study is to investigate the utility of inferior vena cava (IVC) measurements using HCU as an imaging modality to accurately assess IVS in hemodialysis patients. The potential impact would be a portable, cost-efficient, and accurate measurement of patient volume status in order to improve hemodialysis prescriptions and fluid homeostasis. This prospective study involved ESRD patients on hemodialysis at a single tertiary care centre. IVC diameter (IVCdi) and collapsibility index (IVCci) were measured at three hemodialysis sessions for each patient. At each dialysis session, pre-, mid-, and post-dialysis values were collected. IVC parameters were compared to clinical indices of volume status including blood pressure, patient symptoms, and ultrafiltration. A total of 29 patients were included in this study (19 males, mean age 63±16 years). The mean IVC diameter for the pre-dialysis, mid-dialysis, and post-dialysis time points was 1.65±0.40 cm, 1.29 ± 0.33 cm, and 1.39±0.32 cm, respectively (p<0.05). The IVCdi decreased in size from the pre-dialysis to mid-dialysis time points and subsequently increased at the post-dialysis measurement (Figure 1). A subset of 5 patients came back for an additional scan two hours after their dialysis session ended; their IVC diameters continued to increase in size toward pre-dialysis levels. A comparison of IVCdi measurements and clinical indices demonstrated a significant correlation only between post-dialytic IVCdi and post-dialytic symptoms. IVCci did not correlate with blood pressure, volume removal, or patient symptoms at any of the three time points. IVC indices by HCU did not correlate with changes in systolic blood pressure, ultrafiltration, or patient symptoms. These clinical determinants of volume status are inherently inaccurate and do not disprove the validity of HCU in volume assessments. Further studies are warranted to evaluate the benefit of HCU guided hemodialysis prescriptions on patient morbidity and mortality.

Impact of Body Size on Inferior Vena Cava Parameters for Estimating Right Atrial Pressure: A Need for Standardization?

Inferior vena cava (IVC) diameter and its respiratory change, as determined using echocardiography, are commonly used to assess right atrial pressure (RAP). Despite the widespread use of the IVC approach for RAP assessment, the relations among body surface area (BSA), IVC diameter, and respirophasic change remain unclear. The aim of this study was to investigate the impact of BSA on IVC parameters for predicting elevated RAP. Ninety consecutive patients undergoing right-heart catheterization or central venous catheter insertion were prospectively included. To investigate the impact of BSA on IVC parameters, patients were divided into higher and lower BSA groups by comparing individual BSA measurements with the median value. Optimal cutoff points of IVC parameters for detecting RAP of ≥ 10 mm Hg were defined using receiver operating characteristic curves. The median RAP and BSA were 8 mm Hg (range, 1-25 mm Hg) and 1.61 m(2) (range, 1.23-2.22 m(2)), respectively. In all patients, the optimal cutoff point for maximal IVC diameter (IVCDmax) and IVC collapsibility for the detection of RAP ≥ 10 mm Hg were 20 mm and 49.0%, respectively. The optimal cutoff point of IVCDmax for predicting RAP of ≥ 10 mm Hg was significantly larger in patients with higher BSAs than in those with lower BSAs (21 vs 17 mm, P = .0342). No differences in collapsibility indices were detected between the two groups. IVCDmax was larger in men (19 ± 5 vs 17 ± 5 mm in women, P = .0347) and weakly correlated with BSA (r = 0.35, P = .0007), whereas no relation was found between IVCDmax and age. However, the partial correlation coefficient of the entire cohort demonstrated that only BSA was still associated with IVCDmax after adjusting for age and gender (partial correlation coefficient = 0.32, P = .0020). Body size, measured as BSA, is important to consider when IVC diameter is used to assess RAP. The optimal cutoff point of IVCDmax was 21 mm for patients with larger BSAs and 17 mm for those with smaller BSAs. However, the cutoff point of IVC collapsibility was not influenced by the difference of BSA.