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

Left Ventricular Geometry and Inferior Vena Cava Diameter Co-Modify the Risk of Cardiovascular Outcomes in Chronic Hemodialysis Patients

Background and Objectives: Left ventricular hypertrophy (LVH) represents a significant cardiovascular risk in patients undergoing chronic hemodialysis (CHD). A large inferior vena cava diameter (IVCD), potentially indicative of fluid overload and a contributing factor to elevated cardiovascular risk, has not been sufficiently explored. Therefore, our study aims to gain further insights into this aspect. Materials and Methods: A retrospective cohort study enrolled patients receiving CHD in a single medical center with available echocardiography from October to December 2018. They were categorized into four groups based on LVH geometry and IVCD. Cox proportional hazard models assessed the risk of major adverse cardiovascular effects (MACEs) and cardiovascular and overall mortality after multivariate adjustments. Kaplan-Meier analysis depicted MACE-free events and survival during the follow-up time. Results: Of the 175 CHD patients, 38, 42, 45, and 50 exhibited small IVCD with eccentric and concentric LVH and large IVCD with eccentric and concentric LVH, respectively. Compared to small IVCD and eccentric LVH, large IVCD and eccentric LVH had the highest risk of MACEs, followed by large IVCD and concentric LVH (aHR: 4.40, 3.60; 95% CI: 1.58-12.23, 1.28-10.12, respectively). As for cardiovascular mortality, large IVCD and concentric LVH had the highest risk, followed by large IVCD and eccentric LVH, and small IVCD and concentric LVH. (aHR: 14.34, 10.23, 8.87; 95% CI: 1.99-103.35, 1.41-74.33; 1.01-77.87). The trend in overall mortality risk among the groups was similar to that of cardiovascular mortality. Conclusions: LVH geometry and IVCD co-modify the risk of MACEs and cardiovascular and overall mortality in CHD patients. The highest risk of MACEs is associated with large IVCD and eccentric LVH, while the highest risk of cardiovascular and overall mortality is linked with large IVCD and concentric LVH.

A haptic guidance system for simulated catheter navigation with different kinaesthetic feedback profiles

BACKGROUND

This paper proposes a haptic guidance system to improve catheter navigation within a simulated environment.

METHODS

Three force profiles were constructed to evaluate the system: collision prevention; centreline navigation; and a novel force profile of reinforcement learning (RL). All force profiles were evaluated from the left common iliac to the right atrium.

RESULTS

Our findings show that providing haptic feedback improved surgical safety compared to visual-only feedback. If staying inside the vasculature is the priority, RL provides the safest option. It is also shown that the performance of each force profile varies in different anatomical regions.

CONCLUSION

The implications of these findings are significant, as they hold the potential to improve how and when haptic feedback is applied for cardiovascular intervention.

Preoperative Ultrasound for the Prediction of Postinduction Hypotension: A Systematic Review and Meta-Analysis

Postinduction hypotension (PIH) is closely associated with postoperative adverse outcomes. Preoperative hypovolemia is a key risk factor, and many parameters are available from ultrasound to detect hypovolemia, but the accuracy of PIH from ultrasound remains unclear. This systematic review and meta-analysis aimed to evaluate the commonly used measurements from ultrasound to predict PIH. We searched the PubMed, Cochrane Library, Embase, CNKI, and Web of Science databases from their inception to December 2023. Thirty-six studies were included for quantitative analysis. The pooled sensitivities for the inferior vena cava collapsibility index (IVC-CI), maximum inferior vena cava diameter (DIVCmax), minimum inferior vena cava diameter (DIVCmin), and carotid artery corrected flow time (FTc) were 0.73 (95% CI = 0.65, 0.79), 0.66 (95% CI = 0.54, 0.77), 0.74 (95% CI = 0.60, 0.85), and 0.81 (95% CI = 0.72, 0.88). The pooled specificities for the IVC-CI, DIVCmax, DIVCmin, and carotid artery FTc were 0.82 (95% CI = 0.75, 0.87), 0.75 (95% CI = 0.66, 0.82), 0.76 (95% CI = 0.65, 0.84), and 0.87 (95% CI = 0.77, 0.93). The AUC for the IVC-CI, DIVCmax, DIVCmin, and carotid artery FTc were 0.84 (95% CI = 0.81, 0.87), 0.77 (95% CI = 0.73, 0.81), 0.82 (95% CI = 0.78, 0.85), and 0.91 (95% CI = 0.88, 0.93). Our study demonstrated that ultrasound indices are reliable predictors for PIH. The carotid artery FTc is probably the optimal ultrasound measurement for identifying patients who will develop PIH in our study.

Intraprocedural Use of the Novel Protrieve Sheath Removes Embolus During Mechanical Thrombectomy of a Complex Iliocaval Deep Vein Thrombosis

Extension of proximal deep vein thrombosis (DVT) into the inferior vena cava (IVC) complicates treatment with mechanical thrombectomy, as the presence of IVC thrombus increases embolization risks. In the case of a 39-year-old man with left-sided iliocaval DVT, the novel Protrieve sheath (Inari Medical, Irvine, California) was intraprocedurally placed in the IVC to ensure such complications would not outweigh the benefits of intervention. During successful thrombectomy, the sheath's wall-apposing funnel trapped and removed procedural embolus from the IVC, with no complications occurring. Studies to determine whether the device can broadly improve the safety of complex DVT procedures are warranted.

Deep learning in vivo catheter tip locations for photoacoustic-guided cardiac interventions

Significance

Interventional cardiac procedures often require ionizing radiation to guide cardiac catheters to the heart. To reduce the associated risks of ionizing radiation, photoacoustic imaging can potentially be combined with robotic visual servoing, with initial demonstrations requiring segmentation of catheter tips. However, typical segmentation algorithms applied to conventional image formation methods are susceptible to problematic reflection artifacts, which compromise the required detectability and localization of the catheter tip.

Aim

We describe a convolutional neural network and the associated customizations required to successfully detect and localize in vivo photoacoustic signals from a catheter tip received by a phased array transducer, which is a common transducer for transthoracic cardiac imaging applications.

Approach

We trained a network with simulated photoacoustic channel data to identify point sources, which appropriately model photoacoustic signals from the tip of an optical fiber inserted in a cardiac catheter. The network was validated with an independent simulated dataset, then tested on data from the tips of cardiac catheters housing optical fibers and inserted into ex vivo and in vivo swine hearts.

Results

When validated with simulated data, the network achieved an F 1 score of 98.3% and Euclidean errors (mean ± one standard deviation) of 1.02 ± 0.84    mm for target depths of 20 to 100 mm. When tested on ex vivo and in vivo data, the network achieved F 1 scores as large as 100.0%. In addition, for target depths of 40 to 90 mm in the ex vivo and in vivo data, up to 86.7% of axial and 100.0% of lateral position errors were lower than the axial and lateral resolution, respectively, of the phased array transducer.

Conclusions

These results demonstrate the promise of the proposed method to identify photoacoustic sources in future interventional cardiology and cardiac electrophysiology applications.

Ultrasonographic measurement of caudal vena cava to aorta ratio during fluid resuscitation of dogs with spontaneous circulatory shock

OBJECTIVES

To describe the change in the caudal vena cava to aorta ratio (CVC:Ao) ratio during fluid resuscitation of circulatory shock in dogs and compare these results with those of the physical examination and blood lactate.

MATERIALS AND METHODS

Perfusion parameters and blood lactate were recorded at admission. An abdominal point-of-care ultrasound protocol was performed, during which the caudal vena cava to aorta ratio was measured on the spleno-renal view. Measurements were performed within 5 minutes before and after a 10 mL/kg crystalloid fluid bolus. Investigators were not blinded to therapeutic interventions.

RESULTS

Twenty-nine dogs with physical signs of circulatory shock were enrolled. Caudal vena cava to aorta ratios were below reference interval in 28 of 29 dogs. After bolus administration, median caudal vena cava diameter increased by 0.14 cm (0.69 to 0.83 cm) and median aorta diameter increased by 0.03 cm (0.87 to 0.90 cm) and caudal vena cava to aorta ratio returned to within reference range in 65% of dogs (13/29). Bolus administration was associated with an increase in median caudal vena cava to aorta ratio of 0.10 (95% CI:0.05 to 0.16, P=0.0005). Blood lactate did not change significantly. Heart rate and capillary refill time decreased significantly after fluid bolus (heart rate: estimate=-19 bpm, 95% CI:-30 to -8, P=0.002; capillary refill time: estimate=-1.0 s, 95% CI:-1.3 to -0.7, P < 0.0001).

CLINICAL SIGNIFICANCE

In this population of dogs with circulatory shock, the caudal vena cava to aorta ratio significantly increased after a fluid bolus. Future studies that implement blinding of the outcome assessors are warranted to confirm these findings.

Establishment of Reference Intervals for Caudal Vena Cava-to-Aorta Ratio Measured Ultrasonographically in Healthy Nonsedated Dogs

The ultrasonographic assessment of the caudal vena cava-to-aorta ratio (CVC:Ao) appears to be a promising method for early recognition of alterations of intravascular volume status in veterinary medicine. The primary objective of this study was to establish the reference intervals of the CVC:Ao ratio with ultrasound in nonsedated healthy dogs. Secondary objectives were to determine the influence of the respiratory cycle and to evaluate correlations between ultrasonographic measurements, signalment and physical exam findings. Ultrasonographic measurements of Ao and CVC diameters were successfully obtained for all sixty dogs included. No evidence of a difference was observed between the measurements of Ao and CVC diameters, and CVC:Ao ratio between inspiration and expiration (P = .373, P = .318, and P = .537, respectively). The reference interval for CVC:Ao ratio (95% CI), generated from US measurements performed at any moment of the respiratory cycle was defined as 0.93 (0.91-0.95) -1.32 (1.30-1.34). The CVC:Ao ratio was significantly negatively correlated with age (r = -0.341, P = .008) and positively correlated with respiratory rate (r = 0.423, P < .001), but not with heart rate (P = .573) or arterial systolic blood pressure (P = .166). A low inter- and intraoperator variability in repeated measurements was observed for each operator and between operators. The ultrasonographic measurement of the CVC:Ao ratio appears as a simple method with low inter- and intraoperator variability using the ultrasonographic protocol described in the current study. With the reference interval established in the present study in healthy nonsedated dogs, further studies should evaluate the utility of this simple method in assessing and monitoring volume status in hypo- and hypervolemic dogs.

The potential of point-of-care diagnostics to optimise prehospital trauma triage: a systematic review of literature

PURPOSE

In the prehospital care of potentially seriously injured patients resource allocation adapted to injury severity (triage) is a challenging. Insufficiently specified triage algorithms lead to the unnecessary activation of a trauma team (over-triage), resulting in ineffective consumption of economic and human resources. A prehospital trauma triage algorithm must reliably identify a patient bleeding or suffering from significant brain injuries. By supplementing the prehospital triage algorithm with in-hospital established point-of-care (POC) tools the sensitivity of the prehospital triage is potentially increased. Possible POC tools are lactate measurement and sonography of the thorax, the abdomen and the vena cava, the sonographic intracranial pressure measurement and the capnometry in the spontaneously breathing patient. The aim of this review was to assess the potential and to determine diagnostic cut-off values of selected instrument-based POC tools and the integration of these findings into a modified ABCDE based triage algorithm.

METHODS

A systemic search on MEDLINE via PubMed, LIVIVO and Embase was performed for patients in an acute setting on the topic of preclinical use of the selected POC tools to identify critical cranial and peripheral bleeding and the recognition of cerebral trauma sequelae. For the determination of the final cut-off values the selected papers were assessed with the Newcastle-Ottawa scale for determining the risk of bias and according to various quality criteria to subsequently be classified as suitable or unsuitable. PROSPERO Registration: CRD 42022339193.

RESULTS

267 papers were identified as potentially relevant and processed in full text form. 61 papers were selected for the final evaluation, of which 13 papers were decisive for determining the cut-off values. Findings illustrate that a preclinical use of point-of-care diagnostic is possible. These adjuncts can provide additional information about the expected long-term clinical course of patients. Clinical outcomes like mortality, need of emergency surgery, intensive care unit stay etc. were taken into account and a hypothetic cut-off value for trauma team activation could be determined for each adjunct. The cut-off values are as follows: end-expiratory CO2: < 30 mm/hg; sonography thorax + abdomen: abnormality detected; lactate measurement: > 2 mmol/L; optic nerve diameter in sonography: > 4.7 mm.

DISCUSSION

A preliminary version of a modified triage algorithm with hypothetic cut-off values for a trauma team activation was created. However, further studies should be conducted to optimize the final cut-off values in the future. Furthermore, studies need to evaluate the practical application of the modified algorithm in terms of feasibility (e.g. duration of application, technique, etc.) and the effects of the new algorithm on over-triage. Limiting factors are the restriction with the search and the heterogeneity between the studies (e.g. varying measurement devices, techniques etc.).

Evaluation of Cardiac, Autonomic Functions in Ambulant Patients with Duchenne Muscular Dystrophy

Duchenne muscular dystrophy (DMD) is an X-linked genetic disorder caused by dystrophin gene mutation resulting in muscle weakness, motor delays, difficulty in standing, and inability to walk by 12 years. As disease progresses, it leads to cardiac and respiratory failure. Evaluation of cardiac autonomic status and echocardiography in DMD patients at a young age can be a potential biomarker to assess disease progression. This study aimed to investigate the younger DMD population of 5-11years of age with mild to moderate cardiac involvement for early detection using non-invasive and cost-effective tools. Genetically confirmed male DMD patients, aged 5-11 years (n = 47), screened from the outpatient department of a tertiary neuroscience institution were subjected to heart rate variability and echocardiographic analysis, and values were correlated with their clinical variables. DMD patients showed a significantly higher difference in HR, interventricular septum, E m/s, and E-wave to A-wave (E/A) ratio than normal values (p < 0.001). Significantly higher HR indicates initial sinus tachycardia and decreased IVD (d), and increased E m/s and E/A ratio mark the onset of cardiac symptoms in DMD patients even though its chamber dimension remains normal and are associated with cardiac muscle fibrosis.

Evaluation of Normal Inferior Vena Cava Diameters in the Indian Adult Population by Computed Tomography

Background The imaging evaluation of inferior vena cava (IVC) diameters is essential for the estimation of vena caval pathologies and can also detect early hypovolemic shock. There are very few studies on normal IVC diameters on CT scan done in foreign countries, and none done in the Indian population. Aims The goal of this research is to assess the normal IVC diameter in the Indian adult population by performing a CT scan of the abdomen. Material and methods In this study, CT scans of 200 individuals (aged 19-83) without any circulatory and vascular disorders were analyzed retrospectively. The anteroposterior (AP) and transverse diameters of the IVC were measured at the level of the renal vein and at the level 2 cm proximal to insertion in the heart (usual area of measurement on ultrasonography). Results The study discovered normal adult mean AP and transverse dimensions of the IVC at the level of the renal vein as 16.3 ± 2.9 mm and 25.8 ± 3.5 mm, respectively, and 16.9 + 3.2 mm and 26.2 + 3.6 mm at the level 2 cm proximal to its insertion in the right atrium. Conclusions In this study, the normal morphometric dimensions of the IVC in the Indian adult population were established. The diameters of the IVC and the age of the participants in our study had no statistically significant correlation, however, the IVC changes its cross-sectional area and diameter due to changes in venous pressure and blood pressure and hence is a highly compliant vessel. The results of the study will be used as baseline data for the assessment of IVC disorders.

Dual-wavelength photoacoustic atlas method to estimate fractional methylene blue and hemoglobin contents

SIGNIFICANCE

Methylene blue (MB) is an exogenous contrast agent that has the potential to assist with visualization and penetration challenges in photoacoustic imaging. However, monitoring the local concentration between MB and endogenous chromophores is critical for avoiding unnecessary MB accumulations that could lead to adverse effects such as hemolysis when exposed to increased dose and photodamage when exposed to high laser energies.

AIM

We developed a modified version of a previously proposed acoustic-based atlas method to estimate concentration levels from a mixture of two photoacoustic-sensitive materials after two laser wavelength emissions.

APPROACH

Photoacoustic data were acquired from mixtures of 100-μM MB and either human or porcine blood (Hb) injected in a plastisol phantom, using laser wavelengths of 710 and 870 nm. An algorithm to perform linear regression of the acoustic frequency response from an atlas composed of pure concentrations was designed to assess the concentration levels from photoacoustic samples obtained from 11 known MB/Hb volume mixtures. The mean absolute error (MAE), coefficient of determination (i.e., R2), and Spearman's correlation coefficient (i.e., ρ) between the estimated results and ground-truth labels were calculated to assess the algorithm performance, linearity, and monotonicity, respectively.

RESULTS

The overall MAE, R2, and ρ were 12.68%, 0.80, and 0.89, respectively, for the human Hb dataset and 9.92%, 0.86, and 0.93, respectively, for the porcine Hb dataset. In addition, a similarly linear relationship was observed between the acoustic frequency response at 2.3 MHz and 870-nm laser wavelength and the ground-truth concentrations, with R2 and | ρ | values of 0.76 and 0.88, respectively.

CONCLUSIONS

Contrast agent concentration monitoring is feasible with the proposed approach. The potential for minimal data acquisition times with only two wavelength emissions is advantageous toward real-time implementation in the operating room.

Renal vein measurement using ultrasonography in patients with cirrhotic ascites and congestive heart failure

PURPOSE

Ascites can cause compression of the inferior vena cava (IVC), leading to increased renal venous pressure and renal congestion. Previously, the left renal vein diameter in liver cirrhosis patients with ascites was measured using computed tomography, showing that enlargement of the left renal vein diameter affects the prognosis. Herein, the diameter and flow velocity of the renal veins were measured using ultrasonography.

METHODS

Abdominal ultrasonography was performed on 186 patients. The patients were divided into four groups: normal liver (n = 102), liver cirrhosis (LC) without ascites (n = 37), LC with ascites (n = 30), and congestive liver (n = 17). Ultrasonographic measurements for diameter and flow velocity of the IVC, left renal vein main trunk, and segmental renal vein were performed.

RESULTS

The left renal vein diameter increased in the following order: normal liver, LC, LC with ascites, and congestive liver groups (P < 0.001). IVC flow velocity was lower and left renal vein diameter was larger in the congestive liver and LC with ascites groups. These results suggest that the two groups have different pathological conditions, but the mechanism of renal congestion is similar. In patients with LC, IVC compression due to ascites might cause blood stagnation and renal congestion.

CONCLUSION

The left renal vein and IVC can be measured using ultrasonography. It might help in furthering our understanding of the pathophysiology of renal congestion in these patients.

Computational fluid dynamics of the right atrium: Assessment of modelling criteria for the evaluation of dialysis catheters

Central venous catheters are widely used in haemodialysis therapy, having to respect design requirements for appropriate performance. These are placed within the right atrium (RA); however, there is no prior computational study assessing different catheter designs while mimicking their native environment. Here, a computational fluid dynamics model of the RA, based on realistic geometry and transient physiological boundary conditions, was developed and validated. Symmetric, split and step catheter designs were virtually placed in the RA and their performance was evaluated by: assessing their interaction with the RA haemodynamic environment through prediction of flow vorticity and wall shear stress (WSS) magnitudes (1); and quantifying recirculation and tip shear stress (2). Haemodynamic predictions from our RA model showed good agreement with the literature. Catheter placement in the RA increased average vorticity, which could indicate alterations of normal blood flow, and altered WSS magnitudes and distribution, which could indicate changes in tissue mechanical properties. All designs had recirculation and elevated shear stress values, which can induce platelet activation and subsequently thrombosis. The symmetric design, however, had the lowest associated values (best performance), while step design catheters working in reverse mode were associated with worsened performance. Different tip placements also impacted on catheter performance. Our findings suggest that using a realistically anatomical RA model to study catheter performance and interaction with the haemodynamic environment is crucial, and that care needs to be given to correct tip placement within the RA for improved recirculation percentages and diminished shear stress values.

Point-of-Care Ultrasound in Acute Care Nephrology

The use of point-of-care ultrasound (POCUS) is rapidly increasing in nephrology. It provides the opportunity to obtain complementary information that is more accurate than the classic physical examination. One can quickly follow the physical examination with a systematic POCUS evaluation of the kidneys, ureter bladder, inferior vena cava, heart, and lungs, which can provide diagnostic information and an accurate assessment of the patient's hemodynamics and volume status. Moreover, because it is safe and relatively easy to perform, it can be performed in a repeated manner as often as necessary so that the physician can reassess the patient's hemodynamics and volume status and adjust their therapy accordingly, permitting a more personalized approach to patient care (rather than blindly following protocols), especially to patients in acute care nephrology. Despite these advantages, nephrologists have been slow to adopt this diagnostic modality, perhaps because of lack of expertise. This review will provide an overview of the most commonly used POCUS examinations performed by nephrologists in the acute care setting. Its aim is to spark interest in in POCUS and to lay the foundation for readers to pursue more advanced training so that POCUS becomes a readily available tool in your diagnostic arsenal.

Dynamic assessment of the central vein throughout the cardiac cycle in adults with no right heart disease by cardiac CT

PURPOSE

The aim of this study was to investigate the effect of the cardiac cycle on the vena cava and determine the phase of measuring maximum diameters.

METHODS

A total of 152 patients who underwent cardiac computed tomography (CT) were included. Patients' basic information was collected. The major axis, minor axis, and cross-sectional area (CSA) of the vena cava in 10 phases reconstructed at 10% step from 5% to 95% R-R interval were measured in four planes (SVC1 layer: the bifurcation of the pulmonary artery; SVC2 layer: the superior vena cava (SVC) into the right atrium; IVC1 layer: the intersection of the inferior vena cava (IVC) and the right atrium; IVC2 layer: the IVC into the anterior hepatic plane). The difference in vena cava diameters between cardiac cycles was determined using the linear mixed model.

RESULTS

The variations in diameter and CSA of the SVC in cardiac cycles were statistically significant (p < 0.05), while those of the suprahepatic IVC were not. In the SVC1 layer, the maximum value of the SVC major and minor axes was observed in 85% and 45% phases, respectively, while that in the SVC2 layer was observed in 45% phases. The maximum SVC diameters in the SVC1 and SVC2 layers were 19.48 ± 2.57 mm and 17.43 ± 3.09 mm, respectively. The SVC and IVC diameters and CSA were positively correlated with the body surface area in the linear mixed model.

CONCLUSION

The maximum SVC diameter and CSA were mostly observed in 45% phase, which provides a reference for selecting the best phase to measure the abnormality of vena cava diameter in the future.

Differences in pharmacological property between combined therapy of the vasopressin V2-receptor antagonist tolvaptan plus furosemide and monotherapy of furosemide in patients with hospitalized heart failure

BACKGROUND

Tolvaptan has been shown to improve congestion in heart failure patients. The purpose of this study was to evaluate the pharmacology and clinical efficacy of combined tolvaptan and furosemide therapy.

METHODS

This study included 40 patients with systemic volume overload who were hospitalized for heart failure. Patients who showed no improvement in the condition after receiving 20 mg intravenous furosemide were included and were randomly selected to receive tolvaptan as an add-on to furosemide or to receive an increased dose of furosemide. We evaluated the bioelectrical impedance analyzer parameters, the parameters of the inferior vena cava using echocardiography, vital signs, body weight, urine output, and laboratory data for 5 days.

RESULTS

In the changes from baseline between intracellular water volume (ICW) and extracellular water volume (ECW) after additional use of tolvaptan or furosemide from Day 1 to Day 5, there were no significant differences observed between ICW and ECW over 5 days in the tolvaptan + furosemide group, although differences were found in the furosemide group from Day 2 onward. Changes in the respiratory collapse of inferior vena cava increased significantly, and systolic blood pressure decreased significantly only in the furosemide group.

CONCLUSIONS

The present study clearly demonstrates that combined therapy with tolvaptan and furosemide removed excess ICW and ECW to an equal extent, while furosemide alone primarily removed ECW, including intravascular water.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

A comparison of noninvasive methods for early detection of hemorrhage: Inferior vena cava ultrasonography and spectrophotometric hemoglobin levels

OBJECTIVES

Blood hemoglobin concentration measurements using a spectrophotometric method (SpHb), and inferior vena cava ultrasonography (IVC-US) are noninvasive methods used to follow-up hemorrhages. We compared their efficacy using voluntary blood donation as a model of moderate (approx. 500 mL) blood loss.

METHODS

In this prospective observational study enrolling blood-donor volunteers (BD) and matched controls, we recorded SpHb, IVC diameters, and vital signs. Changes in variables from baseline were compared between BD and controls using the paired t test and Wilcoxon signed rank test.

RESULTS

We included 118 subjects in the BD group and 95 healthy subjects in the control group. Changes in IVC maximum diameter, IVC minimum diameter, pulse rate, mean arterial pressure, pulse pressure, and shock index, but not in other variables, were significantly different in the BD and the control group (P < 0.05). IVCmax ≥1.1 mm yielded a 74% sensitivity and 77% specificity (PPV 79.8%, NPV 70.2%) in detecting early hemorrhage. With these cutoff values, IVCmax or PR reached a 90% sensitivity, while IVCmin and PR reached 98% specificity.

CONCLUSIONS

IVC ultrasound may be superior to SpHb in predicting blood loss and may be useful in addition to vital signs for its follow-up.

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

BACKGROUND

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

OBJECTIVES

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

ANIMALS

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

METHODS

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

RESULTS

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

CONCLUSIONS AND CLINICAL IMPORTANCE

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

Correlation of IVC Diameter and Collapsibility Index With Central Venous Pressure in the Assessment of Intravascular Volume in Critically Ill Patients

Objective

The objective of our study is to assess the correlation between inferior vena cava (IVC) diameters, central venous pressure (CVP) and the IVC collapsibility index for estimating the volume status in critically ill patients.

Methods

This cross-sectional study used the convenient sampling of 100 adult medical intensive care unit (ICU) patients for a period of three months. Patients ≥ 18 years of age with an intrathoracic central venous catheter terminating in the distal superior vena cava connected to the transducer to produce a CVP waveform were included in the study. A Mindray diagnostic ultrasound system model Z6 ultrasound machine (Mindray, NJ, USA) was used for all examinations. An Ultrasonic Transducer model 3C5P (Mindray, NJ, USA) for IVC imaging was utilized. A paired sampled t-test was used to compute the p-values.

Results

A total of 32/100 (32%) females and 68/100 (68%) males were included in the study with a mean age of 50.4 ± 19.3 years. The mean central venous pressure maintained was 10.38 ± 4.14 cmH2O with an inferior vena cava collapsibility index of 30.68 ± 10.93. There was a statistically significant relation among the mean CVP pressure, the IVC collapsibility index, the mean maximum and minimum IVC between groups as determined by one-way analysis of variance (ANOVA) (p < 0.001). There was a strong negative correlation between CVP and IVC collapsibility index (%), which was statistically significant (r = -0.827, n = 100, p < 0.0005). A strong positive correlation between CVP and maximum IVC diameter (r = 0.371, n = 100, p < 0.0005) and minimum IVC diameter (r = 0.572, n = 100, p < 0.0005) was found.

Conclusion

There is a positive relationship of CVP with minimum and maximum IVC diameters but an inverse relationship with the IVC collapsibility index.