Wall shear stress measurement in carotid artery phantoms with variation in degree of stenosis using plane wave vector doppler

Wall shear stress (WSS) plays an important role in the formation, growth, and rupture of atherosclerotic plaques in arteries. This study measured WSS in diseased carotid artery phantoms with degrees of stenosis varying from 0 to 60% with both steady and pulsatile flow. Experiments were performed using in silico and real flow phantoms. Blood velocities were estimated using plane wave (PW) vector Doppler. Wall shear stress was then estimated from the velocity gradient near the wall multiplied by the viscosity of a blood-mimicking fluid. The estimated WSS using the in silico phantom agreed within 10% of the ground-truth values (root-mean-square error). The phantom experiment showed that the mean WSS and maximum WSS increased with the increasing degree of stenosis. The simulation and experiment results provide the necessary validation data to give confidence in WSS measurements in patients using the PW vector Doppler technique

Geoeconomic variations in epidemiology, ventilation management, and outcomes in invasively ventilated intensive care unit patients without acute respiratory distress syndrome: a pooled analysis of four observational studies

Background: Geoeconomic variations in epidemiology, the practice of ventilation, and outcome in invasively ventilated intensive care unit (ICU) patients without acute respiratory distress syndrome (ARDS) remain unexplored. In this analysis we aim to address these gaps using individual patient data of four large observational studies. Methods: In this pooled analysis we harmonised individual patient data from the ERICC, LUNG SAFE, PRoVENT, and PRoVENT-iMiC prospective observational studies, which were conducted from June, 2011, to December, 2018, in 534 ICUs in 54 countries. We used the 2016 World Bank classification to define two geoeconomic regions: middle-income countries (MICs) and high-income countries (HICs). ARDS was defined according to the Berlin criteria. Descriptive statistics were used to compare patients in MICs versus HICs. The primary outcome was the use of low tidal volume ventilation (LTVV) for the first 3 days of mechanical ventilation. Secondary outcomes were key ventilation parameters (tidal volume size, positive end-expiratory pressure, fraction of inspired oxygen, peak pressure, plateau pressure, driving pressure, and respiratory rate), patient characteristics, the risk for and actual development of acute respiratory distress syndrome after the first day of ventilation, duration of ventilation, ICU length of stay, and ICU mortality. Findings: Of the 7608 patients included in the original studies, this analysis included 3852 patients without ARDS, of whom 2345 were from MICs and 1507 were from HICs. Patients in MICs were younger, shorter and with a slightly lower body-mass index, more often had diabetes and active cancer, but less often chronic obstructive pulmonary disease and heart failure than patients from HICs. Sequential organ failure assessment scores were similar in MICs and HICs. Use of LTVV in MICs and HICs was comparable (42\ub74% vs 44\ub72%; absolute difference \u20131\ub769 [\u20139\ub758 to 6\ub711] p=0\ub767; data available in 3174 [82%] of 3852 patients). The median applied positive end expiratory pressure was lower in MICs than in HICs (5 [IQR 5\u20138] vs 6 [5\u20138] cm H2O; p=0\ub70011). ICU mortality was higher in MICs than in HICs (30\ub75% vs 19\ub79%; p=0\ub70004; adjusted effect 16\ub741% [95% CI 9\ub752\u201323\ub752]; p<0\ub70001) and was inversely associated with gross domestic product (adjusted odds ratio for a US$10 000 increase per capita 0\ub780 [95% CI 0\ub775\u20130\ub786]; p<0\ub70001). Interpretation: Despite similar disease severity and ventilation management, ICU mortality in patients without ARDS is higher in MICs than in HICs, with a strong association with country-level economic status. Funding: No funding

Improved needle

An improved needle for use in ultrasound guided techniques and administration of regional and/or local anaesthetic is described. The improved needle has a substantially cylindrical shaft having a proximal and distal end, with the distal end being cut substantially perpendicular to the longitudinal axis. In one embodiment the improved needle is provided with an internal protrusion which deflects the path of a catheter inserted through the needle. A further embodiment is provided with wings which can be attached to a support member provided with the needle in alternative first and second directions. A further embodiment is provided with a blinder which protrudes at the distal end of the needle and is designed to assist puncturing of the tissue. Embodiments of the improved needle which are echogenically enhanced and a needle assembly are also described

Ultrasound waveguide

An ultrasound waveguide that is attachable to an ultrasound probe so as to identify a target area on a target object. The ultrasound waveguide has an ultrasound transducer coupling means that allows an ultrasound signal to be transmitted through a guide means. The ultrasound waveguide also has a positioning means for positioning the guide means in relation to the target area on the target object. The guide means is provided with a channel that provides a discontinuity within the guide means that causes a discontinuity in the ultrasound signal emitted by the probe. The presence of this discontinuity allow for proper alignment of the ultrasound waveguide with the target object

Ultrasound waveguide

An ultrasound waveguide that is attachable to an ultrasound probe so as to identify a target area on a target object. The ultrasound waveguide has an ultrasound transducer coupling means that allows an ultrasound signal to be transmitted through a guide means. The ultrasound waveguide also has a positioning means for positioning the guide means in relation to the target area on the target object. The guide means is provided with a channel that provides a discontinuity within the guide means that causes a discontinuity in the ultrasound signal emitted by the probe. The presence of this discontinuity allow for proper alignment of the ultrasound waveguide with the target object