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Appropriate use criteria (AUC) are statements that contain indications describing when and how often an intervention should be performed under the optimal combination of scientific evidence, clinical judgment, and patient values while avoiding unnecessary provisions of services. Society of Nuclear

High-intensity focused ultrasound (HIFU) is a non-invasive tool that can be used for targeted thermal ablation treatments. Currently, HIFU is clinically approved for treatment of uterine fibroids, various cancers, and certain brain applications. However, for brain applications such as essential tremors, HIFU can only be used to treat limited areas confined to the center of the brain because of geometrical limitations (shape of the transducer and skull). A major obstacle to advancing this technology is the inability to treat non-central brain locations without causing damage to the skin and/or skull. Previous research has indicated that cavitation-induced bubbles or microbubble contrast agents can be used to enhance HIFU treatments by increasing ablation regions and shortening acoustic exposures at lower acoustic pressures. However, little research has been done to explore the interplay between microbubble concentration and pressure amplitude on HIFU treatments. We developed an in vitro experimental setup to study lesion formation at three different acoustic pressures and three microbubble concentrations. Real-time ultrasound imaging was integrated to monitor initial microbubble concentration and subsequent behavior during the HIFU treatments. Depending on the pressure used for the HIFU treatment, there was an optimal concentration of microbubbles that led to enhanced heating in the focal area. If the concentration of microbubbles was too high, the treatment was detrimentally affected because of non-linear attenuation by the pre-focal microbubbles. Additionally, the real-time ultrasound imaging provided a reliable method to monitor microbubble activity during the HIFU treatments, which is important for translation to in vivo HIFU applications with microbubbles.

International audience; Perianeurysmal hemodynamics play a vital role in the initiation, growth and rupture of intracranial aneurysms. In vitro investigations of aneurysmal hemodynamics are helpful to visualize and measure blood flow, and aiding surgical planning approaches. Improving in vitro model creation can improve the feasibility and accuracy of hemodynamic investigations and surgical planning, improving clinical value. In this study, in vitro models were created from three-dimensional rotational angiography (3DRA) of six patients harboring intracranial aneurysms using a multi-step process involving 3D printing, index of refraction matching and silicone casting that renders the models transparent for flow visualization. Each model was treated with the same commercially-available, patient-specific, endovascular devices (coils and/or stents). All models were scanned by synchrotron X-ray microtomography to obtain high-resolution imaging of the vessel lumen, aneurysmal sac and endovascular devices. Dimensional accuracy was compared by quantifying the differences between the microtomographic reconstructions of the fabricated phantoms and the original 3DRA obtained during patient treatment. True-scale in vitro flow phantoms were successfully created for all six patients. Optical transparency was verified by using an index of refraction matched working fluid that replicated the mechanical behavior of blood. Synchrotron imaging of vessel lumen, aneurysmal sac and endovascular devices was successfully obtained, and dimensional errors were found to be O(100 μm). The creation of dimensionally-accurate, optically-transparent flow phantoms of patient-specific intracranial aneurysms is feasible using 3D printing technology. Such models may enable in vitro investigations of aneurysmal hemodynamics to aid in treatment planning and outcome prediction to devise optimal patient-specific neurointerventional strategies.

We compared mass spectrometric (MS) performance of surface acoustic wave nebulization (SAWN) generated by a single interdigitated transducer (IDT) designed to produce a progressive wave (PW) to one with a dual IDT that can in theory generate standing waves (SW). Given that devices using dual IDTs had been shown to produce fewer large size droplets on average, we hypothesized they would improve MS performance by improving the efficiency of desolvation. Indeed, the SW-SAWN chip provided an improved limit of detection of 1 femtomole of peptide placed on chip making it 100× more sensitive than the PW design. However, as measured by high-speed image recording and phase Doppler particle analyzer measurements, there was only a 26% increase in the small diameter (1-10 µm) droplets produced from the new device, precluding a conclusion that the decrease in droplet size was solely responsible for the improvement in MS signal/noise. Given that the dual IDT design produced a more instantaneous plume than the PW design, the more likely contributor to improved MS signal/noise was concluded to be a higher ion flux entering the mass spectrometer for the dual IDT designs. Notably, the dual IDT device allowed production of much higher quality protein mass spectra up to about 20 kDa, compared with the single IDT device. Copyright © 2016 John Wiley & Sons, Ltd.

High-resolution particle imaging techniques have had a large impact in fluid mechanics over the last decades. In this chapter, we concentrate on particle tracking velocimetry in which trajectories of particles are reconstructed from sets of flow visualisation images recorded in high-speed video. We describe some recent advances stemming from our research in the major steps of the technique: camera calibration and particle stereo-matching, particle tracking algorithms, and noiseless estimation of statistical quantities. Note that this does not intend to be an inclusive review of the literature on the topic. Applications range from the understanding of single phase turbulence to the dispersion of inertial particles.

Central venous catheters (CVCs), placed in the Superior Vena Cava (SVC) for hemodialysis or chemotherapy, are routinely filled while not in use with heparin, an anticoagulant, to maintain patency and prevent thrombus formation at the catheter tip. The heparin-locking procedure, however, places the patient at risk for systemic bleeding, as heparin is known to leak from the catheter into the blood stream. We provide evidence from detailed in-vitro experiments that shows the driving mechanism behind heparin leakage to be convective-diffusive transport due to the pulsatile flow surrounding the catheter. This novel mechanism is supported by experimental planar laser induced fluorescence (PLIF) and particle image velocimetry (PIV) measurements of flow velocity and heparin transport from a CVC placed inside a model SVC inside a pulsatile flow loop. The results predict an initial, fast (< 10s), convection-dominated phase that rapidly depletes the concentration of heparin in the near-tip region, the region of the catheter with side holes. This is followed by a slow, diffusion-limited phase inside the catheter lumen, where the concentration is still high, that is insufficient at replenishing the lost heparin concentration in the near-tip region. The results presented here, which are consistent with previous in vivo estimates of 24-hour leakage rates, predict that the concentration of heparin in the near-tip region is essentially zero for the majority of the interdialytic phase, rendering the heparin locking procedure ineffective.

Background Measurement of mixed venous oxygen saturation helps determine whether cardiac output and oxygen delivery are sufficient for metabolic needs. As recommended by the American Association of Critical-Care Nurses guideline, blood samples for determining mixed venous oxygen saturation are obtained by slowly, in 1 to 2 minutes, withdrawing 1.5 mL of blood from the distal port of the pulmonary artery catheter. In theory, the negative force of rapid withdrawal could pull oxygenated blood from the pulmonary capillary bed, causing falsely elevated saturation values. Objective To determine if the speed of withdrawal affects oxygen content in blood samples used to measure mixed venous oxygen saturation. Methods The sample consisted of heart failure patients with pulmonary artery catheters admitted to a cardiac intensive care unit. A prospective, randomized, 2 × 2 crossover design was used to compare mixed venous oxygen saturation in blood samples obtained quickly or slowly. A total of 50 sets of saturation values were analyzed. Each set included 1 blood sample obtained slowly, in 1 to 2 minutes, and 1 obtained rapidly, in 5 seconds. Results The mean difference in saturation values between the fast and the slow groups was -0.3 (CI, -1.5 to 0.8; P = .55), indicating that no meaningful systematic bias is attributable to fast withdrawal of blood. Conclusions Rapid blood sampling does not falsely elevate measurements of mixed venous oxygen saturation.

Background The Accreditation Council for Graduate Medical Education Resident-Fellow Survey measurement of compliance with duty hours uses remote retrospective resident report, the accuracy of which has not been studied. We investigated residents' remote recall of 16-hour call-shift compliance and workload characteristics at 1 institution. Methods We sent daily surveys to second- and third-year internal medicine residents immediately after call shifts from July 2011 to June 2012 to assess compliance with 16-hour shift length and workload characteristics. In June 2012, we sent a survey with identical items to assess residents' retrospective perceptions of their call-shift compliance and workload characteristics over the preceding year. We used linear models to compare on-call data to residents' retrospective data. Results We received a survey response from residents after 497 of 648 call-shifts (77% response). The end-of-year perceptions survey was completed by 87 of 95 residents (92%). Compared with on-call data, the recollections of 5 (6%) residents were accurate; however, 48 (56%) underestimated and 33 (38%) overestimated compliance with the 16-hour shift length requirement. The average magnitude of under- and overestimation was 18% (95% confidence interval = 13–23). Using a greater than 10% absolute difference to define under- and overestimation, 39 (45%) respondents were found to be accurate, 27 (31%) underestimated compliance, and 20 (23%) overestimated compliance. Residents overestimated census size, long call admissions, and admissions after 5 pm. Conclusions Internal medicine residents' remote retrospective reporting of compliance with the 16-hour limit on continuous duty and workload characteristics was inaccurate compared with their immediate recall and included errors of underestimation and overestimation.

Background Impairment of coronary microvascular perfusion is common among patients with ST-segment elevation myocardial infarction (STEMI) treated with primary percutaneous coronary intervention (PCI). Cardiovascular magnetic resonance imaging (CMR) can identify microvascular obstruction (MO) following reperfusion of STEMI. We hypothesized that myocardial perfusion, as assessed by the Thrombolysis in Myocardial Infarction (TIMI) Myocardial Perfusion Grade (TMPG), would be associated with a CMR metric of MO in this population. Methods Twenty-one STEMI patients who underwent successful primary PCI were evaluated. Contrast-enhanced CMR was performed within 7 days of presentation and repeated at three months. TIMI Flow Grade (TFG), corrected TIMI Frame Count (cTFC), TMPG, MO, infarct size, and left ventricular ejection fraction (EF) were assessed. Results The median peak creatine phosphokinase (CPK) was 1,775 IU/l (interquartile range 838–3,321). TFG 3 was present following PCI in 19 (90%) patients. CMR evidence of MO was present in 52% following PCI. Abnormal post-PCI TMPG (0/1/2) was present in 48% of subjects and was associated with MO on CMR (90% MO with TMPG 0/1/2 vs. 18% MO with TMPG 3, P

Computational Fluid Dynamics simulations of inspiratory airflow in asymmetric bifurcations have been performed in order to determine the influence of the asymmetry and Reynolds number on pressure losses over a physiological relevant range for pulmonary airways; thus the results of this work can contribute to the understanding of respiratory ventilation in health and in disease. A key a priori insight to the design of the study is that the flow distribution in respiratory bifurcations can be largely independent of the local losses; and therefore, is predetermined by the boundary conditions in these calculations. The results, presented in the form of pressure loss coefficients, indicate that asymmetry and downstream conditions are significant for severe restrictions and laminar flow; but are relatively insignificant for turbulent flow conditions and for flow through the healthy branch.

The distribution of inhaled air throughout human lungs is determined by the pressure losses in lung airways. These losses are reflections of patient health; alterations in measured pressure drops can indicate the presence of respiratory disease [1]. Pressure losses also have implications for the effective treatment of such diseases, as they affect how effectively inhaled medication can be distributed throughout the lung.Copyright © 2012 by ASME

Background We describe a novel laparoscopic "clam shell" partial fundoplication, incorporating a modified Toupet with an anterior fundic flap for the management of medically recalcitrant gastroesophageal reflux disease. We hypothesize that this clam-shell–like mechanism allows a dynamic rather than rigid circumferential antireflux barrier allowing effective reflux control (compared with partial fundoplication) with reduced occurrence of postoperative dysphagia, gas bloating and vagal nerve injury (compared with Nissen fundoplication). Methods Between November 2002 and May 2006, 140 patients (82 female; mean age, 53 years) underwent this laparoscopic clam shell fundoplication procedure for medically recalcitrant gastroesophageal reflux disease (n = 94) or large paraesophageal hernias (n = 46). Preoperative invasive studies (endoscopy, manometry, pH monitoring) and noninvasive studies (barium swallow and radionuclide gastroesophageal motility) revealed esophageal dysmotility in 26 patients. Routine barium swallow and radionuclide studies were performed 6 months postoperatively and then at yearly intervals. Results There was no mortality or conversions to open procedures. Mean operative time was 45 minutes; median hospital stay was 1 day (range, 1 to 4). Overall control of reflux symptoms was seen in 95% of patients. Postoperative gas bloating and significant dysphagia occurred in only 11% and 6% of patients, respectively. Three patients (2%) experienced postoperative complications (pneumonia, 2; pleural effusion requiring drainage, 1). Postoperative studies demonstrated reflux in 8 patients (5%) and the presence of small hiatal hernias in 5 patients (4%) during a mean follow-up 19 months (range, 7 to 42). Twenty five patients (17%) underwent postoperative esophageal dilation (median dilations, 1; range, 1 to 3) for dysphagia (11 of these patients had preoperative esophageal dysmotility). Five patients underwent repeat fundoplication (recurrent reflux, 2; gas bloating, 1; dysphagia, 2). Conclusions Clam shell near-circumferential fundoplication may be considered as an attractive alternative antireflux approach to Nissen fundoplication, particularly among patients at risk for postoperative dysphagia or gas bloating.