Quantifying changes in oxygen saturation of the internal jugular vein in vivo using deep neural networks and subject-specific three-dimensional Monte Carlo models.

Central venous oxygen saturation (ScvO2) is an important parameter for assessing global oxygen usage and guiding clinical interventions. However, measuring ScvO2 requires invasive catheterization. As an alternative, we aim to noninvasively and continuously measure changes in oxygen saturation of the internal jugular vein (SijvO2) by a multi-channel near-infrared spectroscopy system. The relation between the measured reflectance and changes in SijvO2 is modeled by Monte Carlo simulations and used to build a prediction model using deep neural networks (DNNs). The prediction model is tested with simulated data to show robustness to individual variations in tissue optical properties. The proposed technique is promising to provide a noninvasive tool for monitoring the stability of brain oxygenation in broad patient populations.

Differential Assessment of Internal Jugular Vein Stenosis in Patients Undergoing CT and MRI with Contrast.

OBJECTIVE: Internal Jugular Vein Stenosis (IJVS) is hypothesized to play a role in the pathogenesis of diverse neurological diseases. We sought to evaluate differences in IJVS assessment between CT and MRI in a retrospective patient cohort. METHODS: We included consecutive patients who had both MRI of the brain and CT of the head and neck with contrast from 1 June 2021 to 30 June 2022 within the same admission. The degree of IJVS was categorized into five grades (0-IV). RESULTS: A total of 35 patients with a total of 70 internal jugular (IJ) veins were included in our analysis. There was fair intermodality agreement in stenosis grades (κ = 0.220, 95% C.I. = [0.029, 0.410]), though categorical stenosis grades were significantly discordant between imaging modalities, with higher grades more frequent in MRI (χ2 = 27.378, p = 0.002). On CT-based imaging, Grade III or IV stenoses were noted in 17/70 (24.2%) IJs, whereas on MRI-based imaging, Grade III or IV stenoses were found in 40/70 (57.1%) IJs. Among veins with Grade I-IV IJVS, MRI stenosis estimates were significantly higher than CT stenosis estimates (77.0%, 95% C.I. [35.9-55.2%] vs. 45.6%, 95% C.I. [35.9-55.2%], p < 0.001). CONCLUSION: MRI with contrast overestimates the degree of IJVS compared to CT with contrast. Consideration of this discrepancy should be considered in diagnosis and treatment planning in patients with potential IJVS-related symptoms.

First assessment of flow phenomena of acute and chronic thrombosis in the jugular veins using new ultrasound vector-flow imaging.

AIM: First assessment of flow changes in the jugular veins using high resolution ultrasound vector flow. MATERIAL UND METHODS: 15 patients (8 males, 7 females) with an age range of 35 to 82 years (mean age 58.53±12.26 years) were examined by an experienced examiner using high power ultrasound equipment (Resona R9, Mindray) with probe technology (Mindray L9-3U Linear Array transducer, 2.5 to 9.0 MHz). This group was compared with five healthy subjects (mean age 35.4±13.79 years) as a reference. To assess flow changes, the color-coded duplex sonography and the novel vector flow technique were used. The evaluation was performed of vector morphology changes, turbulence, and wall resistance measurements. RESULTS: There were changes after acute and chronic thrombosis in 9 cases, and venous compression in 7 cases. Turbulence was measurable from 0.01 % to 64.44 %, the average turbulence was 19.73±22.06 %. Wall resistance measurement showed values from 0.01 Pa to 3.14 Pa, depending on the age of the thrombosis or compression. The reference veins showed turbulence of 0.94±1.5 % and a mean wall resistance of 0.05±0.05 Pa. There are statistically significant differences between normal and thrombotic or compressed veins in terms of maximum wall stress (p = 0.006) and mean degree of turbulence (p = 0.012), while the difference in mean wall stress is not statistically significant (p = 0.058). CONCLUSION: Despite still existing technical limitations, the combination of V-flow and wall stress measurements in jugular vein changes suggests a high diagnostic potential.

[The assessment of volume status]. / Het beoordelen van de vullingsstatus.

Accurately assessing volume status is crucial, as an incorrect evaluation can lead to inappropriate therapy. Evaluating volume status using medical history and physical examination can be challenging. Medical history and physical examination are readily available, cost-effective, and non-invasive, remaining the initial steps in assessing fluid status. Point-of-care ultrasound (POCUS) is a valuable adjunct to physical examination. The collapse point of the internal jugular vein, the diameter of the inferior vena cava, and the presence of pulmonary B-lines can be easily and rapidly assessed using POCUS. Combining medical history, physical examination, and POCUS enhances diagnostic certainty in evaluating volume status.

Assessment of venous pressure by compression sonography of the internal jugular vein during 3 days of bed rest.

Compression sonography has been proposed as a method for non-invasive measurement of venous pressures during spaceflight, but initial reports of venous pressure measured by compression ultrasound conflict with prior reports of invasively measured central venous pressure (CVP). The aim of this study is to determine the agreement of compression sonography of the internal jugular vein (IJVP) with invasive measures of CVP over a range of pressures relevant to microgravity exposure. Ten healthy volunteers (18-55 years, five female) completed two 3-day sessions of supine bed rest to simulate microgravity. IJVP and CVP were measured in the seated position, and in the supine position throughout 3 days of bed rest. The range of CVP recorded was in line with previous reports of CVP during changes in posture on Earth and in microgravity. The correlation between IJVP and CVP was poor when measured during spontaneous breathing (r = 0.29; R2  = 0.09; P = 0.0002; standard error of the estimate (SEE) = 3.0 mmHg) or end-expiration CVP (CVPEE ; r = 0.19; R2  = 0.04; P = 0.121; SEE = 3.0 mmHg). There was a modest correlation between the change in CVP and the change in IJVP for both spontaneous ΔCVP (r = 0.49; R2  = 0.24; P < 0.0001) and ΔCVPEE (r = 0.58; R2  = 0.34; P < 0.0001). Bland-Altman analysis of IJVP revealed a large positive bias compared to spontaneous breathing CVP (3.6 mmHg; SD = 4.0; CV = 85%; P < 0.0001) and CVPEE (3.6 mmHg; SD = 4.2; CV = 84%; P < 0.0001). Assessment of absolute IJVP via compression sonography correlated poorly with direct measurements of CVP by invasive catheterization over a range of venous pressures that are physiologically relevant to spaceflight. However, compression sonography showed modest utility for tracking changes in venous pressure over time. NEW FINDINGS: What is the central question of this study? Compression sonography has been proposed as a novel method for non-invasive measurement of venous pressures during spaceflight. However, the accuracy has not yet been confirmed in the range of CVP experienced by astronauts during spaceflight. What is the main finding and its importance? Our data show that compression sonography of the internal jugular vein correlates poorly with direct measurement of central venous pressures in a range that is physiologically relevant to spaceflight. However, compression sonography showed modest utility for tracking changes in venous pressure over time.

Assessment of jugular bulb variability based on 3D surface models: quantitative measurements and surgical implications.

PURPOSE: High-riding jugular bulbs (JBs) among other anatomical variations can limit surgical access during lateral skull base surgery or middle ear surgery and must be carefully assessed preoperatively. We reconstruct 3D surface models to evaluate recent JB classification systems and assess the variability in the JB and surrounding structures. METHODS: 3D surface models were reconstructed from 46 temporal bones from computed tomography scans. Two independent raters visually assessed the height of the JB in the 3D models. Distances between the round window and the JB dome were measured to evaluate the spacing of this area. Additional distances between landmarks on surrounding structures were measured and statistically analyzed to describe the anatomical variability between and within subjects. RESULTS: The visual classification revealed that 30% of the specimens had no JB, 63% a low JB, and 7% a high-riding JB. The measured mean distance from the round window to the jugular bulb ranges between 3.22 ± 0.97 mm and 10.34 ± 1.41 mm. The distance measurement (error rate 5%) was more accurate than the visual classification (error rate 15%). The variability of the JB was higher than for the surrounding structures. No systematic laterality was found for any structure. CONCLUSION: Qualitative analysis in 3D models can contribute to a better spatial orientation in the lateral skull base and, thereby, have important implications during planning of middle ear and lateral skull base surgery.

Portable ultrasound assessment of jugular venous pressure is an accurate method for estimating volaemic status in patients with cardiac disease.

PURPOSE: The objective of this study was to determine whether ultrasound-measured jugular venous pressure (U-JVP) could accurately estimate central venous pressure (CVP). METHODS: This prospective, diagnostic, single-centre study was performed at the Cardiac Intensive Care Unit of the Northern General Hospital, Sheffield, UK. Post-cardiac surgery patients were recruited from January to May 2019. The investigators were blinded to the central venous pressure when measuring the jugular venous pressure. U-JVP and direct CVP were measured simultaneously. Measurements were taken whilst the patient was ventilated and then repeated when the patient was extubated, providing non-ventilated readings. RESULTS: One-hundred and fourteen consecutive participants with a male predominance of 71% and mean age of 65 ± 12 years were included in the analysis. Bland-Altman plots revealed that U-JVP marginally overestimated CVP by 0.91 mmHg (95% limits of agreement were -2.936 to 4.754) in ventilated patients and by 0.11 mmHg (95% limits of agreement between -2.481 and 2.695) in non-ventilated patients. Reasonable sensitivity and specificity of ultrasound-measured jugular venous pressure was achieved for low and high central venous pressure in both ventilated and non-ventilated patients. CONCLUSION: U-JVP accurately estimates cardiac filling pressure and fluid status in patients after cardiac surgery, irrespective of their ventilatory status. Jugular venous pressure measurement by insonation is a reliable technique that can be taught to medical students and other health professionals to non-invasively estimate central venous pressure and may be useful for assessment of volaemic status in patients with heart failure. TRIAL REGISTRATION: ClinicalTrials.gov public (identifier NCT03815188).

Characteristics of the Maternal Jugular Venous Pulse Waveform by Combined Doppler-Electrocardiogram Assessment.

Standardized combined Doppler-electrocardiogram assessment was performed longitudinally at three different locations of internal jugular veins between 12 wk of gestation and 6 wk postnatally in 24 uncomplicated pregnancies. All images were classified as typical or non-typical based on the presence of the physiologic deflections A, X, H and C. Linear mixed models with random intercepts of typical images were used to investigate gestational changes in venous pulse transit time and venous impedance index. Unequivocal identification of venous pulse transit time and venous impedance index was possible in 2617 of 3798 (69%) and 2234 of 3798 (59%) images, respectively. The best identification rate (80%, 1018/1266) was at the right distal internal jugular vein. Venous pulse transit time increased with gestational age at all locations; venous impedance index decreased at the right sided internal jugular vein. Maternal jugular venous pulse waveform by combined Doppler-electrocardiogram allows unequivocal identification of A-deflection and calculation of venous pulse transit time and venous impedance index in around two-thirds of assessments, with the highest success rate at the right distal internal jugular vein. Gestational evolutions of venous pulse transit time and venous impedance index are similar to those reported at the level of renal interlobar and hepatic veins.

Jugular Venous Pressure Response to Inspiration for Risk Assessment of Heart Failure.

Simplifying jugular venous pressure (JVP), visibility of the right internal jugular vein above the right clavicle in the sitting position, has been proposed in the management of heart failure (HF) because of its convenience. However, this method may be undervalued for the detection of mildly to moderately increased JVP. Increased JVP on inspiration, known as Kussmaul sign, may be a useful physical finding in this condition. This study consisted of 138 patients who were admitted for the management of HF. Using this simple method, JVP was assessed at rest in the sitting position before discharge; its response to inspiration was also examined if no high JVP was noted at rest. The primary outcome was a composite of cardiac death and hospitalization for worsening HF. Among all the patients, 16 patients (12%) had high JVP at rest and another 16 patients (12%) had high JVP not at rest but on inspiration. During a follow-up period of 249 ± 182 days, a primary outcome event occurred in 63 patients (46%). The incidence of adverse cardiac events was higher in patients with a high JVP at rest (69%; hazard ratio 3.31, 95% confidence interval 1.64 to 6.67, p = 0.0009) and in patients with a high JVP on inspiration (56%; hazard ratio 2.18, 95% confidence interval 1.02 to 4.63, p = 0.043) than in patients without a high JVP in both conditions (41%). In conclusion, a high JVP not only at rest but also on inspiration was associated with a poor prognosis. The response of JVP to inspiration using this simple technique of physical examination may be a new approach in the management of HF.

The risk of fatal bleeding complications in jugular catheterization in patients with coagulopathy: A retrospective analysis of death cases in closed claims and the Medical Accident Investigating System in Japan.

BACKGROUND: To prevent recurrence of medical accidents, the Medical Accident Investigating System was implemented in October 2015 by the Japan Medical Safety Research Organization (Medsafe Japan) to target deaths from medical care that were unforeseen by the administrator. Medsafe Japan analyzed the 10 cases of central venous catheterization-related deaths reported in the system and published recommendations in March 2017. However, the particular emphasis for the prevention of central venous catheterization-related deaths is unclear. METHODS: This study aimed to identify the recommendation points that should be emphasized to prevent recurrence of central venous catheterization-related deaths. We assessed central venous catheterization in 8530 closed-claim cases between January 2002 and December 2016 covered by the medical insurer Sompo-Japan. Moreover, we compared central venous catheterization-related death in closed-claim cases with death in reported cases. RESULTS: The background, error type, anatomic insertion site, and fatal complication data were evaluated for 37 closed-claim cases, of which 12 (32.4%) were death cases. Of the 12 closed-claim cases and 10 reported cases, 9 (75.0%) closed-claim cases and 9 (90.0%) reported cases were related to vascular access. Among these, 5 closed-claim cases (41.7%) and 7 reported cases (77.8%) were related to internal jugular vein catheterization (p = 0.28). Coagulopathy was observed in 3 (60.0%) of 5 closed-claim cases and 6 (85.7%) of 7 reported cases. CONCLUSIONS: The risk of internal jugular catheterization in patients with coagulopathy must be carefully considered.

Point-of-Care Ultrasound for Central Venous Assessment in the Emergency Department: A Prospective Study Comparing the Femoral and Internal Jugular Veins.

OBJECTIVES: The objective of this study was to estimate the width, height, and depth of the femoral vein (FV) and internal jugular vein (IJV), both sites of potential central line placement in children, using point-of-care ultrasound. METHODS: This was a prospective observational study. Point-of-care ultrasound was used to measure the width, height, and depth of the right FV and IJV in 100 children. The primary outcome was a comparison of the widths of the FV and the IJV in the same child. Our primary hypothesis was that the IJV would be wider than the FV. Secondary outcome measures included comparison of the heights and depths the FV and IJV and description of vessel overlap frequency between the 2 sites. RESULTS: A total of 106 children were enrolled, with 6 subjects excluded, and equally divided into 5 age groups (0-30 days, 1-24 months, 2-5 years, 6-11 years, and 12-17 years). The FV/IJV width ratios (95% confidence interval) by age were 0.58 (0.49-0.68), 0.53 (0.43-0.66), 0.57 (0.49-0.67), 0.68 (0.55-0.85), and 0.73 (0.62-0.85), all P < 0.002. The FV/IJV height ratios were <1 in all age groups, with P < 0.003 in the 4 youngest age groups. The FV/IJV depth ratios were >1 in 6 to 11 years (P = 0.018) and 12 to 17 years (P < 0.001). CONCLUSIONS: The IJV was significantly wider and taller than the FV in the same child in all age groups. The FV was significantly deeper than the IJV in children 6 years and older. This supports the use of the IJV as a potential site when placing ultrasound-guided central lines in children.

Central venous pressure estimation from ultrasound assessment of the jugular venous pulse.

OBJECTIVES: Acquiring central venous pressure (CVP), an important clinical parameter, requires an invasive procedure, which poses risk to patients. The aim of the study was to develop a non-invasive methodology for determining mean-CVP from ultrasound assessment of the jugular venous pulse. METHODS: In thirty-four adult patients (age = 60 ± 12 years; 10 males), CVP was measured using a central venous catheter, with internal jugular vein (IJV) cross-sectional area (CSA) variation along the cardiac beat acquired using ultrasound. The resultant CVP and IJV-CSA signals were synchronized with electrocardiogram (ECG) signals acquired from the patients. Autocorrelation signals were derived from the IJV-CSA signals using algorithms in R (open-source statistical software). The correlation r-values for successive lag intervals were extracted and used to build a linear regression model in which mean-CVP was the response variable and the lagging autocorrelation r-values and mean IJV-CSA, were the predictor variables. The optimum model was identified using the minimum AIC value and validated using 10-fold cross-validation. RESULTS: While the CVP and IJV-CSA signals were poorly correlated (mean r = -0.018, SD = 0.357) due to the IJV-CSA signal lagging behind the CVP signal, their autocorrelation counterparts were highly positively correlated (mean r = 0.725, SD = 0.215). Using the lagging autocorrelation r-values as predictors, mean-CVP was predicted with reasonable accuracy (r2 = 0.612), with a mean-absolute-error of 1.455 cmH2O, which rose to 2.436 cmH2O when cross-validation was performed. CONCLUSIONS: Mean-CVP can be estimated non-invasively by using the lagged autocorrelation r-values of the IJV-CSA signal. This new methodology may have considerable potential as a clinical monitoring and diagnostic tool.

Correlation and assessment of coronary artery luminal stenosis: Post-mortem computed tomography angiogram versus histopathology.

BACKGROUND: Post-mortem Computed Tomography (PMCT) allows non-invasive or minimally invasive detection of findings that may or may not be visible during conventional autopsy, however, it does not allow the investigator to draw any conclusions regarding patency of the vessel's lumen. To address this deficiency, Post-mortem Computed Tomography Angiography (PMCTA) utilizing different contrast media and techniques have been introduced with various studies looking at the correlation between PMCTA, autopsy (gross) findings and coronary artery histology in diagnosing coronary artery disease. OBJECTIVES: The aim of this study is to investigate the sensitivity and specificity of PMCTA in diagnosing coronary artery stenosis using water-based contrast media introduced though the vessels of the neck, compared to the gold standard of diagnosis i.e. gross and histological evaluation of the coronary artery. METHOD: This was a cross sectional study of 158 arterial sections involving 37 subjects recruited from the National Institute of Forensic Medicine (IPFN), Hospital Kuala Lumpur (HKL). An unenhanced PMCT was performed followed by PMCTA using water-based contrast media introduced though the vessels of the neck. Coronary artery stenosis was determined using multiplanar reconstructionD while the degree of stenosis was determined by calculating the percentage of luminal diameter divided by the diameter of the vessel internal elastic. RESULTS: The analysis of PMCTA and histopathology examinations revealed a sensitivity of 61.5%, specificity of 91.7%; positive predictive value (PPV) of 40.0% and negative predictive value (NPV) of 96.4%. CONCLUSION: PMCTA utilizing water-based contrast introduced though the vessels of the neck yielded similar results as other methods and techniques of PMCTA. We would therefore conclude that PMCTA utilizing this technique could be used to assess the degree of calcification and the presence of significant stenosis.

Homologous and heterologous assessment of a novel biomaterial for venous patch.

OBJECTIVE: This study evaluated swine and bovine pulmonary visceral pleura (PVP) as a vascular patch. Venous patches are frequently used in surgery for repair or reconstruction of veins. Autologous patches are often limited by the number and dimension of donor tissue and can result in donor complications. Bovine pericardium is the most common heterologous patch used by vascular surgeons. Researchers, however, are continually seeking to improve heterologous and synthetic patches for improved outcome. METHODS: The PVP was peeled from swine and bovine lungs and cross-linked with glutaraldehyde. After sterilization and rinsing, the PVP patches were implanted in the jugular vein (10 × 35 mm) of pigs and dogs. Patency was evaluated by ultrasound, and animals were euthanized at 2 and 4 months. Neoendothelium and neomedia were evaluated by histologic analysis. RESULTS: The jugular vein patched by PVP in pigs and dogs remained patent at 2 and 4 months with no adhesions, inflammation, or aneurysm in the patches. The biomarkers of endothelial cells-factor VIII, platelet/endothelial cell adhesion molecule 1, and endothelial nitric oxide synthase-were detected in the neoendothelial cells. The expression of vascular smooth muscle cell (VSMC) α-actin was robust in the neomedia at 2 and 4 months. Neomedia composed of VSMCs developed to nearly double the thickness of adjacent jugular vein. The circumferential orientation of VSMCs in neomedia further increased in the 4-month group. CONCLUSIONS: The cross-linked swine and bovine PVP patch has a nonthrombogenic surface that maintains patency. The PVP patch may overcome the pitfall of compliance mismatch of synthetic patches. The proliferation of vascular cells assembled in the neoendothelium and neomedia in the patches may support long-term patency.

Feasibility of a Porcine Arteriovenous Shunt Model for Assessment of Acute Thrombogenicity in Bifurcation Stenting Technique By Optical Coherence Tomography.

BACKGROUND: Double kissing (DK) crush stenting has been reported as a superior bifurcation stenting strategy compared to culotte stenting. However, the mechanism associated with the reduction of clinical events by DK crush stenting remains unclear. We therefore investigated the thrombogenicity of DK crush stenting and culotte stenting with both bare-metal stents (BMS) and drug-eluting stents (DES) and the feasibility of a novel porcine arteriovenous shunt model. METHODS: High-resolution intracoronary imaging with optical coherence tomography (OCT) evaluated the bifurcation stenting models for thrombogenicity. RESULTS: All porcine models retained continuous circulation without blood leakage. Thrombus was macroscopically demonstrated around the bifurcation in all settings. The volume of thrombus (mm3) with BMS using DK crush/culotte and DES using DK crush/culotte were 1.38/1.19 and 0.09/0.15, respectively. Culotte stenting had more thrombus in the proximal main branch, and DK crush stenting had more at the bifurcation. Unlike DK crush stenting, culotte stenting showed malapposition in the proximal main branch and bifurcation segments. CONCLUSION: The feasibility of a porcine arteriovenous shunt model to assess thrombogenicity by OCT in bifurcation stenting technique was confirmed. OCT detected less thrombogenicity in DES when used in the bifurcation model when compared to BMS.

Cephalic vein approach for the implantable central venous access: A retrospective review of the single institution's experiences; Cohort Study.

Long-term venous access is usually required in patients receiving chemotherapy. We hypothesized that, out of the various central line approach techniques, the cephalic vein cut-down technique can be a safe and simple alternative in terms of surgical safety, feasibility, cost-effectiveness, and functional outcomes.We retrospectively reviewed the medical records of 569 patients who underwent implantable central venous access between January 2012 and December 2014 at our hospital.We classified our cohort according to access routes, as follows: 230 patients underwent subclavian vein access, 134 patients underwent internal jugular vein access, 25 patients underwent external jugular vein access, and 119 patients underwent cephalic vein access. The cephalic vein group had a significantly longer operation time than the subclavian group (P < .01); however, there was no difference in operation time between the internal jugular vein and cephalic vein groups (P = .59). The procedure-related complications and functional outcomes of the implanted venous port during chemotherapy were comparable between the cephalic group and other groups. Additionally, body mass index, operation time, and age did not correlate with catheter dysfunction in the multivariate logistic regression analysis (P = .53; P = .66; P = .19, respectively).We suggest that a cut-down central venous catheter insertion through the cephalic vein can be performed easily and safely with no differences in surgical and clinical outcomes compared to those of conventional percutaneous approaches. Moreover, the cephalic vein approach requires no specialized equipment, including percutaneous vascular kits, tunneling instruments, and intraoperative ultrasonography. Therefore, this technique might incur less medical expenses than conventional approaches and would be helpful for both patients and surgeons.

Assessment of Jugular Venous Blood Flow Stasis and Thrombosis During Spaceflight.

Importance: Exposure to a weightless environment during spaceflight results in a chronic headward blood and tissue fluid shift compared with the upright posture on Earth, with unknown consequences to cerebral venous outflow. Objectives: To assess internal jugular vein (IJV) flow and morphology during spaceflight and to investigate if lower body negative pressure is associated with reversing the headward fluid shift experienced during spaceflight. Design, Setting, and Participants: This prospective cohort study included 11 International Space Station crew members participating in long-duration spaceflight missions . Internal jugular vein measurements from before launch and approximately 40 days after landing were acquired in 3 positions: seated, supine, and 15° head-down tilt. In-flight IJV measurements were acquired at approximately 50 days and 150 days into spaceflight during normal spaceflight conditions as well as during use of lower body negative pressure. Data were analyzed in June 2019. Exposures: Posture changes on Earth, spaceflight, and lower body negative pressure. Main Outcomes and Measures: Ultrasonographic assessments of IJV cross-sectional area, pressure, blood flow, and thrombus formation. Results: The 11 healthy crew members included in the study (mean [SD] age, 46.9 [6.3] years, 9 [82%] men) spent a mean (SD) of 210 (76) days in space. Mean IJV area increased from 9.8 (95% CI, -1.2 to 20.7) mm2 in the preflight seated position to 70.3 (95% CI, 59.3-81.2) mm2 during spaceflight (P < .001). Mean IJV pressure increased from the preflight seated position measurement of 5.1 (95% CI, 2.5-7.8) mm Hg to 21.1 (95% CI, 18.5-23.7) mm Hg during spaceflight (P < .001). Furthermore, stagnant or reverse flow in the IJV was observed in 6 crew members (55%) on approximate flight day 50. Notably, 1 crew member was found to have an occlusive IJV thrombus, and a potential partial IJV thrombus was identified in another crew member retrospectively. Lower body negative pressure was associated with improved blood flow in 10 of 17 sessions (59%) during spaceflight. Conclusions and Relevance: This cohort study found stagnant and retrograde blood flow associated with spaceflight in the IJVs of astronauts and IJV thrombosis in at least 1 astronaut, a newly discovered risk associated with spaceflight. Lower body negative pressure may be a promising countermeasure to enhance venous blood flow in the upper body during spaceflight.

Ultrasonographic assessment of normal jugular veins in Standardbred horses.

BACKGROUND: Ultrasonography (US) is the recommended imaging technique to evaluate jugular veins. This prospective randomized clinical study was designed to collect a series of B-mode US measurements of manually distended jugular veins in healthy Italian Standardbreds and to find possible correlations between ultrasound measurements and animal morphometric characteristics. Forty-two horses, eight males and 34 females (range 3-22 years; bodyweight 494.4 ± 41.7 kg), were included in the study. The diameters and wall thicknesses of both jugular veins were measured at three different sites of the neck. The differences in ultrasound measurements based on scans, age, gender, side, and site of the neck were evaluated by ANOVA or by the Kruskal-Wallis test. The effects of the morphometric measures on each ultrasound parameter were evaluated by MANOVA (P < 0.05). RESULTS: The ultrasound measurements did not differ significantly between the three different sites or between genders; hence, they were pooled together in the results. On the transverse scan, the mean dorsoventral and lateromedial diameters were 1.58 ± 0.23 and 2.20 ± 0.25 cm, respectively; the mean superficial and deep wall thicknesses (SWT and DWT) were 0.07 ± 0.01 and 0.08 ± 0.01 cm, respectively. On the longitudinal scan, the mean dorsoventral diameter was 1.59 ± 0.26 cm, and the SWT and DWT were both 0.08 ± 0.01 cm. Neck length, from the caudal edge of the mandible to the thoracic inlet, was related to the dorsoventral diameter in both longitudinal and transverse scan and to the SWT and DWT in transverse scan, whereas height at the withers (measured with tape) and estimated weight were related to the wall thickness. Dividing the subjects into groups by age in years ("young" 3-7, "mature" 8-14, "old" > 14), differences were found for the lateromedial diameter in the transverse scan and the SWT on the longitudinal scan. The main limitation of this study was that only one operator performed the measurements. CONCLUSION: The US measurements of the jugular veins and their relationship with morphometric measures reported in this manuscript might be considered as guidelines both for early diagnosis and monitoring jugular vein abnormalities in healthy Italian Standardbred horses.

Use of point-of-care ultrasound for the assessment of intravascular volume in five rural New Zealand hospitals.

INTRODUCTION: Measuring the diameter of the inferior vena cava (IVC) or the height of the jugular venous pressure (JVP) with point-of-care ultrasound (POCUS) is a practical alternative method for estimating a patient's intravascular volume in the rural setting. This study aims to determine whether or not POCUS of the IVC or JVP generates additional useful clinical information over and above routine physical examination in this context. METHODS: Twenty generalist physicians, working in five New Zealand rural hospitals, recorded their estimation of a patient's intravascular volume based on physical examination and then again after performing POCUS of the IVC or JVP, using a visual scale from 1 to 11. RESULTS: Data were available for 150 assessments. There was an only moderate agreement between the pre- and post-test findings (Spearman's correlation coefficient = 0.46). In 28% (42/150) of cases, the difference was four or more points on the scale, and therefore, had the potential to be clinically significant. CONCLUSION: In the rural context, POCUS provides new information that frequently alters the clinician's estimation of a patient's intravascular volume.

Résumé Introduction: La mesure du diamètre de la veine cave inférieure ou de la hauteur de la pression veineuse jugulaire à l'aide de l'échographie au point de service est une méthode pratique pour estimer le volume intravasculaire d'un patient en région rurale. Cette étude vise à déterminer si oui ou non l'échographie au point de service de la veine cave inférieure ou de la pression veineuse jugulaire génère un surcroît d'information clinique utile par rapport à l'examen physique de routine dans ce contexte. Méthodologie: Vingt médecins généralistes de 5 hôpitaux des régions rurales de la Nouvelle-Zélande ont noté sur une échelle visuelle de 1 à 11 leur estimation du volume intravasculaire des patients basée sur l'examen physique, puis après une échographie au point de service de la veine cave inférieure ou de la pression veineuse jugulaire. Résultats: Des données se rapportant à 150 évaluations étaient disponibles. La concordance entre les résultats d'avant le test et d'après le test n'était que modérée (coefficient de corrélation de Spearman = 0,46). Dans 28 % (42/150) des cas, la différence était de quatre points ou plus sur l'échelle et avait donc le potentiel d'être cliniquement significative. Conclusion: En contexte rural, l'échographie au point de service fournit de nouveaux renseignements qui altèrent fréquemment l'estimation du volume intravasculaire par le clinicien. Mots-clés: Échographie, évaluation du volume, point de service, rural, veine cave inférieure.