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.

Tibial anterior compartment compressibility in healthy subject, measured using compression sonography.

INTRODUCTION: Compression sonography has been introduced for non-invasive measurement of compartment compressibility and possible diagnostic tool for acute or chronic compartment syndrome in studies using human cadavers and animal models. To date, standard values in healthy subjects are not yet defined. The aim was to define standard compartment compressibility values in healthy human subjects and to assess the reliability of this measurement method. METHODS: In 60 healthy volunteers, using ultrasound, the diameter of the tibial anterior compartment was measured while applying no pressure, 10mbar and 80mbar of external pressure. A pressure manometer on the ultrasound head was used to monitor the externally applied pressure. Compartment compressibility ratio (R0-80, respectively R10-80) was calculated as following: The delta of the compartment diameter with high and low external pressure, divided through the diameter with low external pressure. In 10 volunteers, two examinators conducted each two measurements to assess the reliability. RESULTS: Mean compartment compressibility ratio R10-80 was 15.9% ±3.6 (range: 7.2 - 22.2). Mean compartment compressibility ratio R0-80 was 18.2% ±5.0 (3.0 - 32.1). There was no significant correlation with lower leg circumference, height, weight, BMI, gender, hours of sport per week and type of sport (e.g. weightlifting/ cardio). For R10-80, intraobserver ICC 2.1 was 0.89 for an experienced observer and 0.79 for a non-experienced observer. Interobserver ICC 2.1 was 0.78. For R0-80, intraobserver ICC 2.1 was 0.71 for the experienced and 0.56 for the unexperienced observer. Interobserver ICC 2.1 was 0.59. DISCUSSION: In healthy volunteers between 18 and 50 years of age, mean compartment compressibility ratio R10-80 was 15.9% ±3.6, independent of demographic factors and sport activity. Application of 10mbar instead of 0mbar increased image quality. Subsequently, R10-80 showed lower standard deviation and both higher intraobserver and interobserver reliability than R0-80. Using R10-80, this measurement method is reliable with very high intra- and interobserver correlation.

A Diagnostic Algorithm Based on a Simple Clinical Prediction Rule for the Diagnosis of Cranial Giant Cell Arteritis.

BACKGROUND: Risk stratification based on pre-test probability may improve the diagnostic accuracy of temporal artery high-resolution compression sonography (hrTCS) in the diagnostic workup of cranial giant cell arteritis (cGCA). METHODS: A logistic regression model with candidate items was derived from a cohort of patients with suspected cGCA (n = 87). The diagnostic accuracy of the model was tested in the derivation cohort and in an independent validation cohort (n = 114) by receiver operator characteristics (ROC) analysis. The clinical items were composed of a clinical prediction rule, integrated into a stepwise diagnostic algorithm together with C-reactive protein (CRP) values and hrTCS values. RESULTS: The model consisted of four clinical variables (age > 70, headache, jaw claudication, and anterior ischemic optic neuropathy). The diagnostic accuracy of the model for discrimination of patients with and without a final clinical diagnosis of cGCA was excellent in both cohorts (area under the curve (AUC) 0.96 and AUC 0.92, respectively). The diagnostic algorithm improved the positive predictive value of hrCTS substantially. Within the algorithm, 32.8% of patients (derivation cohort) and 49.1% (validation cohort) would not have been tested by hrTCS. None of these patients had a final diagnosis of cGCA. CONCLUSION: A diagnostic algorithm based on a clinical prediction rule improves the diagnostic accuracy of hrTCS.

Temporal artery compression sonography for the diagnosis of giant cell arteritis in elderly patients with acute ocular arterial occlusions.

OBJECTIVES: To validate cut-off values of quantitative high-resolution temporal artery compression sonography (TCS) for the diagnosis of cranial GCA (cGCA) in patients with acute arterial ocular occlusions and in an independent control group. METHODS: Consecutive patients who underwent TCS as part of the diagnostic workup of acute arterial ocular occlusions and controls not suffering from ocular ischaemia/systemic vasculitis were included. The diagnostic accuracy of the established TCS cut-off value of maximum temporal artery wall thickness (≥0.7 mm) and a novel numeric TCS score incorporating the degree of wall thickening in the four temporal artery segments assessed (0-3 points per segment) was tested by receiver operating characteristics analysis. Subgroup analyses were performed for female and male patients and patients older and younger than age of 70 years. RESULTS: Of 114 patients with acute ocular arterial occlusions, 30 patients received a final clinical diagnosis of cGCA. The sensitivity and specificity of the ≥0.7 mm TCS cut-off for the diagnosis of cGCA were 100 and 84.5% in the overall cohort. The TCS score did not improve the diagnostic yield (cut-off ≥5; sensitivity 100%, specificity 85.7%). In male patients >70 years of age, the specificity of TCS was limited, secondary to age- and sex-related differences in temporal artery wall thickness, which we confirmed in the independent control group. CONCLUSION: TCS yields high diagnostic accuracy in the diagnosis of cGCA in patients with acute ocular arterial occlusions. Age- and sex-related differences in temporal artery wall thickness influence the diagnostic accuracy of TCS.

Compression sonography for non-invasive measurement of lower leg compartment pressure in an animal model.

INTRODUCTION: Compression ultrasound is a non-invasive technique allowing for qualitative visualization and quantitative measurements of mechanical tissue properties. In acute compartment syndrome (ACS), cadaver studies have proven that the intra-compartmental pressure (ICP) measured by compression sonography correlates with the ICP measured invasively. This study aimed to evaluate compression sonography for compartment pressure measurements in an animal model. MATERIAL AND METHODS: The pressure in the anterior tibial compartment of 6 domestic pig legs was increased from baseline to 40mmHg in 5mmHg steps. Using compression sonography, the compartment diameter was measured without external pressure and during manual application of five levels of external pressure. The elasticity ratio (ER) was computed as the ratio of the compartment diameter with and without external pressure. At 40mmHg of external pressure the ERs at different ICP levels were compared using repeated ANOVA measurements. Post-hoc comparisons evaluated the lowest detectable ICP fulfilling the definition of ACS (ICP≥30mmHg) by starting from each pressure below 30mmHg (baseline, 20mmHg and 25mmHg, respectively). Receiver operator characteristic analyses defined ER limits with appropriate sensitivity and specificity to detect ACS. RESULTS: The ER increased from 79.0% at baseline ICP to 89.3% at 40mmHg ICP. The ER at baseline and at 20mmHg ICP significantly differed from the ER at 30mmHg ICP (p=0.007 and 0.002, respectively); the ER at 25mmHg ICP significantly differed from the ER at 40mmHg ICP (p=0.001). An ER less than 87.1% had a sensitivity of 94.4% and a specificity of 88.9% to proper diagnosis of ACS. CONCLUSION: Compression sonography might offer a non-invasive technique to guide treatment in cases of uncertain acute compartment syndrome. Further studies are needed to collect elasticity ratio data in humans and to clinically validate compression sonography for compartment pressure measurements.

Syncope as a presentation of acute pulmonary embolism.

PURPOSE: Syncope is an atypical presentation for acute pulmonary embolism (APE). There are conflicting data concerning syncope and prognosis of APE. PATIENTS AND METHODS: One hundred and seventy-nine consecutive patients aged 22-96 years (median, 68 years) with APE were retrospectively enrolled in the study. RESULTS: Prevalence of syncope was 13% (n=23) at the time of presentation. Compared to patients without syncope, those with syncope had a higher rate of central embolism (83% vs 43%, respectively, P=0.002), right ventricular dysfunction (91% vs 68%, P=0.021), and troponin positivity (80% vs 39%, P=0.001) but not 30-day mortality (13% vs 10%, P=0.716). Multivariate analysis showed that central localization (odds ratio: 9.08) and cardiac troponin positivity (odds ratio: 4.67) were the independent correlates of the presence of syncope in the patients with APE. Frequency of cardiopulmonary disease was lower, and duration from symptom onset to hospital admission was shorter in patients with syncope (P=0.138 and 0.118, respectively), although not significant. CONCLUSION: Syncope most likely represents an intermediate condition between massive APE and hypotension. In APE patients with syncope, the prognosis seems to depend on the underlying pathology, the patient's age, comorbidities and duration from symptom onset to hospital admission, and the use of thrombolytic therapy.

[Ultrasound in thromboembolism]. / Sonografie bei Thromboembolie.

Imaging of pulmonary embolism (PTE) remains a great challange. Mortatity is even high. Possibilities of lung ultrasound, echocardiography, and compression leg vein sonography are discussed. Hemodynamic instable patients should achieve echocardiography at bed side with an accuracy of 90% and immeadiatly treated. In case of a suspected PTE, compression sonography of the leg veins is recommended. It can be performed within 2 min but, on average, yields a positive result in only one-half of the cases of PTE. During the last years, pulmonary sonography took root as a complementary method to MSCT either when the latter is not available or when it is contraindicated because of contrast agent allergy, renal insufficiency, or pregnancy. This method was able to provide evidence of subpleural pulmonary consolidations due to embolism in at least three-fourths of patients having a PTE. According to clinical presentation, combination of lung ultrasound, echocardiograpphy, and compression ultrasoud of the leg veins showed a sensitiviy of more than 90%.