End-to-End Ultrasonic Hand Gesture Recognition.

As the number of electronic gadgets in our daily lives is increasing and most of them require some kind of human interaction, this demands innovative, convenient input methods. There are limitations to state-of-the-art (SotA) ultrasound-based hand gesture recognition (HGR) systems in terms of robustness and accuracy. This research presents a novel machine learning (ML)-based end-to-end solution for hand gesture recognition with low-cost micro-electromechanical (MEMS) system ultrasonic transducers. In contrast to prior methods, our ML model processes the raw echo samples directly instead of using pre-processed data. Consequently, the processing flow presented in this work leaves it to the ML model to extract the important information from the echo data. The success of this approach is demonstrated as follows. Four MEMS ultrasonic transducers are placed in three different geometrical arrangements. For each arrangement, different types of ML models are optimized and benchmarked on datasets acquired with the presented custom hardware (HW): convolutional neural networks (CNNs), gated recurrent units (GRUs), long short-term memory (LSTM), vision transformer (ViT), and cross-attention multi-scale vision transformer (CrossViT). The three last-mentioned ML models reached more than 88% accuracy. The most important innovation described in this research paper is that we were able to demonstrate that little pre-processing is necessary to obtain high accuracy in ultrasonic HGR for several arrangements of cost-effective and low-power MEMS ultrasonic transducer arrays. Even the computationally intensive Fourier transform can be omitted. The presented approach is further compared to HGR systems using other sensor types such as vision, WiFi, radar, and state-of-the-art ultrasound-based HGR systems. Direct processing of the sensor signals by a compact model makes ultrasonic hand gesture recognition a true low-cost and power-efficient input method.

Friction sensing mechanisms for perception and motor control: passive touch without sliding may not provide perceivable frictional information.

Perception of the frictional properties of a surface contributes to the multidimensional experience of exploring various materials; we slide our fingers over a surface to feel it. In contrast, during object manipulation, we grip objects without such intended exploratory movements. Given that we are aware of the slipperiness of objects or tools that are held in the hand, we investigated whether the initial contact between the fingertip skin and the surface of the object is sufficient to provide this consciously perceived frictional information. Using a two-alternative forced-choice protocol, we examined human capacity to detect frictional differences using touch, when two otherwise structurally identical surfaces were brought in contact with the immobilized finger perpendicularly or under an angle (20° or 30°) to the skin surface (passive touch). An ultrasonic friction reduction device was used to generate three different frictions over each of three flat surfaces with different surface structure: 1) smooth glass, 2) textured surface with dome-shaped features, and 3) surface with sharp asperities (sandpaper). Participants (n = 12) could not reliably indicate which of the two surfaces was more slippery under any of these conditions. In contrast, when slip was induced by moving the surface laterally by a total of 5 mm (passive slip), participants could clearly perceive frictional differences. Thus making contact with the surface, even with moderate tangential forces, was not enough to perceive frictional differences, instead conscious perception required a sufficient size slip.NEW & NOTEWORTHY This study contributes to understanding how frictional information is obtained and used by the brain. When the skin is contacting surfaces of identical topography but varying frictional properties, the deformation pattern is different; however, available sensory cues did not get translated into perception of frictional properties unless a sufficiently large lateral movement was present. These neurophysiological findings may inform how to design and operate haptic devices relying on friction modulation principles.

Comparison of the resonance sonorheometry based Quantra® system with rotational thromboelastometry ROTEM® sigma in cardiac surgery - a prospective observational study.

BACKGROUND: Measures of the sonorheometry based Quantra® viscoelastic hemostatic analyzer (HemoSonics, LCC, Charlottesville, VA, USA) were compared with corresponding results of the ROTEM® sigma device (Instrumentation Laboratory, Bedford, MA, USA). METHODS: In thirty-eight patients scheduled for elective cardiac surgery between December 2018 and October 2019, blood samples were taken after induction of anesthesia (sample 1) and after heparin neutralization (sample 2) and measured on Quantra (QPlus® Cartridge) and ROTEM sigma (ROTEM® sigma complete + hep Cartridge). Clot times and clot stiffness values were recorded. Clot stiffness values of ROTEM amplitudes (A in mm) were converted to shear modulus (G) in hectoPascal (hPa): G (hPa) = (5 x A)/(100-A). Additionally, time-to-results was recorded. Spearman rank test correlation and Bland Altman analysis were performed. RESULTS: Clot stiffness parameters of the Quantra correlated strongly with corresponding measurements of the ROTEM with r = 0.93 and 0.94 for EXTEM A10 vs CS and r = 0.94 and 0.96 for FIBTEM A10 vs FCS for sample 1 and 2, respectively. Quantra clot time correlated strongly with ROTEM INTEM CT with r = 0.71 for sample 1 and r = 0.75 for sample 2. However, Bland Altman analysis showed no agreement in all compared assays of both methods. The median time to delivery of first and complete results was significantly shorter for Quantra (412 and 658 s) compared to ROTEM sigma (839 and 1290 s). CONCLUSIONS: The Quantra showed a strong correlation with the ROTEM sigma for determining clot times and clot stiffness and the parameters assess similar aspects of clot development. However, these parameters are not directly interchangeable and implicate that separate cut-off values need to be established for users of the Quantra device. Word count: 278. TRIAL REGISTRATION: The study was retrospectively registered with ClinicalTrials.gov (ID: NCT04210830 ) at December 20th 2019.

Jean-Louis Luche and the Interpretation of Sonochemical Reaction Mechanisms.

Sonochemistry can be broadly defined as the science of chemical and physical transformations produced under the influence of sound. The use of sound energy is rather a young branch of chemistry and does not have the clear definitive rules of other, more established, divisions such as those in cycloaddition reactions or photochemistry. Nevertheless, there are a few guidelines which can help to predict what is going to happen when a reaction mixture is submitted to ultrasonic irradiation. Jean-Louis Luche, formulated some ideas of the mechanistic pathways involved in sonochemistry more than 30 years ago. He introduced the idea of "true" and "false" sonochemical reactions both of which are the result of acoustic cavitation. The difference was that the former involved a free radical component whereas only mechanical effects played a role the latter. The authors of this paper were scientific collaborators and friends of Jean-Louis Luche during those early years and had the chance to discuss and work with him on the mechanisms of sonochemistry. In this paper we will review the original rules (laws) as predicted by Jean-Louis Luche and how they have been further developed and extended in recent years.

Artificial Intelligence Assisted Ultrasonic Extraction of Total Flavonoids from Rosa sterilis.

Flavonoids in Rosa sterilis were studied. The flavonoids in Rosa sterilis were extracted by ultrasonic method, and the extraction conditions were modeled and optimized by response the surface methodology and the artificial intelligence method. The results show that the ultrasonic method can effectively extract total flavonoids, and the extraction rate is close to the prediction value of ANN-GA algorithm, which proves the rationality of the model. The order of the effects of the parameters on the experiment was material liquid ratio > extraction power > extraction time > ethanol concentration. In addition, the scavenging effects of flavonoids on DPPH, O2-· and ·OH were also determined, and these indicated that flavonoids have strong antioxidant activities. The kinetics of the extraction process was studied by using the data of the extraction process, and it was found that the extraction process conformed to Fick's first law.

Effect of ultrasonic pretreatment monitored by real-time online technologies on dried preparation time and yield during extraction process of okra pectin.

BACKGROUND: Ultrasonic pretreatment is a novel physical method that can be used in the extraction process of okra pectin. Real-time online monitoring technologies were introduced in time and frequency domains when okra was pretreated. Preparation time of dried okra and yield of okra pectin were studied; and physicochemical properties of okra pectin were analyzed at the optimum ultrasonic parameter. RESULTS: Results showed that ultrasonic intensity of sweeping-frequency ultrasonic (SFU) pretreatment was stronger than that of fixed-frequency ultrasonic pretreatment (FFU). SFU pretreatment (60 ± 1 kHz) at 30 min had a strong ultrasonic voltage peak of 0.05387 V and signal power peak of -6.62 dBm. The preparation time of dried okra was 160 ± 14.14 min in the pretreated group, 44.83% lower than control without SFU pretreatment. The intercellular space was 56.03% higher than control. Water diffusion coefficient increased from 1.41 × 10-9 to 2.14 × 10-9  m2  s-1 . Monobasic quadratic equations were developed for the monitored ultrasonic intensity and pectin yield. Compared to control, extraction yield (16.70%), pectin content (0.564 mg mg-1 ), solubility (0.8187 g g-1 ) and gel strength (30.91 g) were improved in the pretreated group. Viscosity decreased, and values of G' and G″ crossing at 63 rad s-1 revealed the viscoelastic behavior and the beginning of viscous behavior with a sol state. CONCLUSION: Decrement of dried preparation time and increment of yield were achieved by ultrasonic pretreatment during the extraction process of okra pectin, and the relationship of ultrasonic intensity monitored by real-time online technologies and yield was given. © 2021 Society of Chemical Industry.

Effect of ultrasound-assisted extraction on the structure and emulsifying properties of peanut protein isolate.

BACKGROUND: With an increasing demand for edible protein, research on new extraction methods is attracting more attention. The effects of such methods on functional properties are important. The present study aimed to evaluate the effect of ultrasound-assisted extraction on the extraction efficiency, structure, and the emulsifying properties of peanut protein isolate (PPI). RESULTS: Ultrasound-assisted extraction significantly improved extraction efficiency and shortened the processing time. The nanostructure, molecular weight distribution, and particle size of PPI were altered by ultrasound-assisted extraction. The emulsifying properties of the PPI from ultrasound-assisted extraction were significantly improved compared with alkaline extraction. Peanut protein isolate had lower molecular weight fractions, higher levels of hydrophobic amino acids, and the highest fluorescence intensity with ultrasound intensity, temperature, and time of 3.17 W cm-3 , 35 °C, and 30 min, respectively. These contributed to the higher emulsifying activity index and emulsifying stability index of the PPI emulsions. The uniform distribution of droplets and smaller particle size of the PPI emulsions was also observed. CONCLUSION: The results suggested that ultrasound can be used to induce the conformational changes to modify the interfacial association between protein-oil phases, thereby improving the emulsifying properties of peanut protein. © 2020 Society of Chemical Industry.

The effect of an ultrasonic spray nozzle on carbohydrate and protein-based coating materials for blueberry extract microencapsulation.

BACKGROUND: An ultrasonic spray nozzle was evaluated for the production of powders and microcapsules, using blueberry extract, modified starch (HI-CAP 100), and whey protein isolate (WPI). The effects of ultrasonic power and the concentration of coating materials on the characteristics of the resulting samples - such as viscosity, particle size, microencapsulation efficiency, color, glass transition temperature, Fourier-transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), and morphology - were also studied. RESULTS: The apparent viscosity was primarily affected by the self-heating of the ultrasonic nozzle as the power increased. The largest mean particle size of samples was observed under conditions of 30% coating concentration at 10 W. Glass transition temperatures (Tg ) of the samples were affected by all atomization parameters significantly (P < 0.05) and the highest Tg values of all samples were determined when the coating concentration was maximum (30%) and power level was minimum (5 W). The FTIR and XRD results indicate that the power of the ultrasonic nozzle did not cause any change in WPI structure and led to only a small change in the structure of HI-CAP 100 at 10 W. The short atomization time preserved, to some extent, the properties of the coating materials and the blueberry extract. With regard to the morphological properties, it was observed that the samples obtained with WPI showed less shrinkage than HI-CAP 100. CONCLUSION: The results indicated that an ultrasonic nozzle could be used successfully to prepare the blueberry microcapsule with HI-CAP 100 and WPI as coating materials. This study may contribute to the development of ultrasonic nozzle applications using different coatings for the microencapsulation of high-quality functional materials. © 2020 Society of Chemical Industry.

Ultrasonic and osmotic pretreatments followed by convective and vacuum drying of papaya slices.

BACKGROUND: Papaya fruit is highly nutritive, but very fragile, and thus has a limited shelf life. Drying is essential to preserve it for longer durations. In this work, osmotic dehydration (OD) with and without ultrasound (US) was applied to papaya slices as a pretreatment in conjugation with vacuum (VD) and convective air drying (AD). Drying was carried out in a novel dryer. Moisture content, drying time, water activity, total color change, total phenolic content, radical scavenging activity, texture, and Fourier-transform infrared (FTIR) spectrums were evaluated for fresh and dried papaya slices. RESULTS: It was observed that US-assisted osmotic dehydration (USOD) followed by VD had the lowest drying time with highest retention of phenols and antioxidants as compared to other drying techniques. Higher phenols and antioxidants in US-pretreated samples were attributed to the release of trapped intra-cellular polyphenols by cavitation. However, the color characteristics and texture of OD pretreatment followed by convective AD slices were found to be better. Color retention could be due to carotenoid preservation, which would be degraded in other treatments, whereas lower brittleness was associated with lower pectin. Infrared spectroscopy confirmed the retention of phytochemicals and antioxidants in dried papaya slices that were subjected to pretreatment. CONCLUSION: Pretreatment before drying enhances the end product quality of dried papaya slices. The results of this study highlight that USOD-VD is effective for nutrition preservation while OD-AD is suitable for preserving physical characteristics. © 2020 Society of Chemical Industry.

FIRST-IN-HUMAN CLINICAL STUDY TO INVESTIGATE THE EFFECTIVENESS AND SAFETY OF PARS PLANA VITRECTOMY SURGERY USING A NEW HYPERSONIC TECHNOLOGY.

PURPOSE: Investigate the effective performance and safety of a new hypersonic vitrector technology. METHODS: Postapproval, prospective, single-arm, noncomparative, open-label study at one clinical site in India. INDICATIONS: macular hole (9/20), vitreous hemorrhage (7/20), vitreomacular traction (3/20), and vitreomacular traction with pseudomacular hole (1/20). Safety endpoints included intraoperative and postoperative adverse events. Effective performance endpoints were surgeon-rated effectiveness, range of surgical time, and device settings. Other performance measures were preoperative and postoperative best-corrected visual acuity, slit-lamp and indirect ophthalmoscopy, applanation tonometry, color fundus photography, fundus fluorescein angiography, and spectral domain optical coherence tomography. RESULTS: Core vitreous removal (20/20 subjects), peripheral vitreous removal (18/20), and posterior vitreous detachment induction (13/15) surgeries were successfully completed. Total surgical time was 22.5 minutes to 106 minutes. Serious adverse events through 3 months were 2 device-associated retinal tears and detachment (one intraoperative) and one unrelated postoperative enlargement of macular hole with subretinal fluid. CONCLUSION: This first-in-human study suggests that this new hypersonic vitrector technology is a promising alternative to commercially available guillotine vitrectors. The hypersonic vitrector was effective in core vitreous removal in all cases. Larger-scale studies are required to expand on our initial findings for induction of a posterior vitreous detachment or peripheral vitrectomy.

Development of an Accurate Resonant Frequency Controlled Wire Ultrasound Surgical Instrument.

Our developed wire ultrasound surgical instrument comprises a bolt-clamped Langevin ultrasonic transducer (BLUT) fabricated by PMN-PZT single crystal material due to high mechanical quality factor and electromechanical coupling coefficient, a waveguide in the handheld instrument, and a generator instrument. To ensure high performance of wire ultrasound surgical instruments, the BLUT should vibrate at an accurate frequency because the BLUT's frequency influences hemostasis and the effects of incisions on blood vessels and tissues. Therefore, we implemented a BLUT with a waveguide in the handheld instrument using a developed assembly jig process with impedance and network analyzers that can accurately control the compression force using a digital torque wrench. A generator instrument having a main control circuit with a low error rate, that is, an output frequency error rate within ±0.5% and an output voltage error rate within ±1.6%, was developed to generate the accurate frequency of the BLUT in the handheld instrument. In addition, a matching circuit between the BLUT and generator instrument with a network analyzer was developed to transfer displacement vibration efficiently from the handheld instrument to the end of the waveguide. Using the matching circuit, the measured S-parameter value of the generator instrument using a network analyzer was -24.3 dB at the resonant frequency. Thus, our proposed scheme can improve the vibration amplitude and accuracy of frequency control of the wire ultrasound surgical instrument due to developed PMN-PZT material and assembly jig process.

Monitoring Mixing Processes Using Ultrasonic Sensors and Machine Learning.

Mixing is one of the most common processes across food, chemical, and pharmaceutical manufacturing. Real-time, in-line sensors are required for monitoring, and subsequently optimising, essential processes such as mixing. Ultrasonic sensors are low-cost, real-time, in-line, and applicable to characterise opaque systems. In this study, a non-invasive, reflection-mode ultrasonic measurement technique was used to monitor two model mixing systems. The two systems studied were honey-water blending and flour-water batter mixing. Classification machine learning models were developed to predict if materials were mixed or not mixed. Regression machine learning models were developed to predict the time remaining until mixing completion. Artificial neural networks, support vector machines, long short-term memory neural networks, and convolutional neural networks were tested, along with different methods for engineering features from ultrasonic waveforms in both the time and frequency domain. Comparisons between using a single sensor and performing multisensor data fusion between two sensors were made. Classification accuracies of up to 96.3% for honey-water blending and 92.5% for flour-water batter mixing were achieved, along with R2 values for the regression models of up to 0.977 for honey-water blending and 0.968 for flour-water batter mixing. Each prediction task produced optimal performance with different algorithms and feature engineering methods, vindicating the extensive comparison between different machine learning approaches.

Synthesis of Natural-Like Snow by Ultrasonic Nebulization of Water: Morphology and Raman Characterization.

The current devices used to produce massive amounts of snow (i.e., snow machines) can be improved with concern to both the energy efficiency and the quality of snow. Here we investigate an alternative snow production method based on the ultrasonic nebulization of water and its subsequent condensation on the cold surfaces of a refrigerator. Inspection of the snow samples with a stereo optical microscope shows both dendritic and granular snow morphologies. The characterization of the samples by Raman spectroscopy shows a behavior consistent with that of a natural, low-density snow. Our results indicate that ultrasonic nebulization of water is an effective strategy for producing natural-like snow at the laboratory scale.

Adjunct use of mouth rinses with a sonic toothbrush accelerates the detachment of a Streptococcus mutans biofilm: an in vitro study.

BACKGROUND: The aim of this in vitro study was to examine the possible enhancement of the biofilm peeling effect of a sonic toothbrush following the use of an antimicrobial mouth rinse. METHODS: The biofilm at a noncontact site in the interdental area was treated by sound wave convection with the test solution or by immersion in the solution. The biofilm peeling effect was evaluated by determining the bacterial counts and performing morphological observations. A Streptococcus mutans biofilm was allowed to develop on composite resin discs by cultivation with stirring at 50 rpm for 72 h. The specimens were then placed in recesses located between plastic teeth and divided into an immersion group and a combination group. The immersion group was treated with phosphate buffer, chlorhexidine digluconate Peridex™ (CHX) mouth rinse or Listerine® Fresh Mint (EO) mouth rinse. The combination group was treated with CHX or EO and a sonic toothbrush. RESULTS: The biofilm thickness was reduced by approximately one-half compared with the control group. The combination treatment produced a 1 log reduction in the number of bacteria compared to the EO immersion treatment. No significant difference was observed in the biofilm peeling effect of the immersion group compared to the control group. CONCLUSIONS: The combined use of a sonic toothbrush and a mouth rinse enhanced the peeling of the biofilm that proliferates in places that are difficult to reach using mechanical stress.

Minireview: Biophysical Mechanisms of Cell Membrane Sonopermeabilization. Knowns and Unknowns.

Microbubble-assisted ultrasound has emerged as a promising method for the delivery of low-molecular-weight chemotherapeutic molecules, nucleic acids, therapeutic peptides, and antibodies in vitro and in vivo. Its clinical applications are under investigation for local delivery drug in oncology and neurology. However, the biophysical mechanisms supporting the acoustically mediated membrane permeabilization are not fully established. This review describes the present state of the investigations concerning the acoustically mediated stimuli (i.e., mechanical, chemical, and thermal stimuli) as well as the molecular and cellular actors (i.e., membrane pores and endocytosis) involved in the reversible membrane permeabilization process. The different hypotheses, which were proposed to give a biophysical description of the membrane permeabilization, are critically discussed.

Advanced nanostructures for cell membrane poration.

Nanostructured devices are able to foster the technology for cell membrane poration. With the size smaller than a cell, nanostructures allow efficient poration on the cell membrane. Emerging nanostructures with various physical transduction have been demonstrated to accommodate effective intracellular delivery. Aside from improving poration and intracellular delivery performance, nanostructured devices also allow for the discovery of novel physiochemical phenomena and the biological response of the cell. This article provides a brief introduction to the principles of nanostructured devices for cell poration and outlines the intracellular delivery capability of the technology. In the future, we envision more exploration on new nanostructure designs and creative applications in biomedical fields.

Real-Time Measurement of Xenon Concentration in a Binary Gas Mixture Using a Modified Ultrasonic Time-of-Flight Anesthesia Gas Flowmeter: A Technical Feasibility Study.

BACKGROUND: Xenon (Xe) is an anesthetic gas licensed for use in some countries. Fractional concentrations (%) of gases in a Xe:oxygen (O2) mixture are typically measured using a thermal conductivity meter and fuel cell, respectively. Speed of sound in such a binary gas mixture is related to fractional concentration, temperature, pressure, and molar masses of the component gases. We therefore performed a study to assess the feasibility of developing a novel single sterilizable device that uses ultrasound time-of-flight to measure both real-time flowmetry and fractional gas concentration of Xe in O2. METHODS: For the purposes of the feasibility study, we adapted an ultrasonic time-of-flight flowmeter from a conventional anesthetic machine to additionally measure real-time fractional concentration of Xe in O2. A total of 5095 readings of Xe % were taken in the range 5%-95%, and compared with simultaneous measurements from the gold standard of a commercially available thermal conductivity Xe analyzer. RESULTS: Ultrasonic measurements of Xe (%) showed agreement with thermal conductivity meter measurements, but there was marked discontinuity in the middle of the measurement range. Bland-Altman analysis (95% confidence interval in parentheses) yielded: mean difference (bias) 3.1% (2.9%-3.2%); lower 95% limit of agreement -4.6% (-4.8% to -4.4%); and upper 95% limit of agreement 10.8% (10.5%-11.0%). CONCLUSIONS: The adapted ultrasonic flowmeter estimated Xe (%), but the level of accuracy is insufficient for clinical use. With further work, it may be possible to develop a device to perform both flowmetry and binary gas concentration measurement to a clinically acceptable degree of accuracy.

An Exploratory Study of Sectra Table Visualization Improves the Effectiveness of Emergency Bedside Echocardiography Training.

OBJECTIVES: Echocardiography is an essential tool in emergency medicine, and its training is the most challenging of all types of bedside ultrasound (US) training. This study investigated the effectiveness of the Sectra Table (Sectra AB, Linköping, Sweden), an anatomy visualization and collaboration tool, in improving the quality of echocardiography training for emergency medicine physicians. METHODS: We conducted an exploratory prospective observational study from 2015 to 2017 and enrolled 66 trainees who participated in a 2.5-day bedside US course organized by the emergency department (ED) of Peking Union Medical College Hospital. The study participants underwent 2 different training programs: the first group received standard training, and the second group was trained with Sectra Table experiences integrated into the echocardiography training curriculum. After the training sessions, both groups were evaluated for their hands-on echocardiography performance. RESULTS: The new training program with the Sectra Table significantly increased trainees' self-confidence in performing bedside echocardiography. The Sectra Table trainees had a higher performance rating than the trainees in the traditional program, with a mean total assessment score of 40.5 versus 26.5 for traditional training (P < .01). The improved performance was evident for all subcategories of echocardiography. The higher performance rating of the Sectra Table trainees was also statistically significant after adjusting for confounders, including prior training experiences, baseline confidence in independently performing ED US examinations, the number of ED US examinations performed, years in ED practice, and physician seniority. CONCLUSIONS: Our analysis suggests that integrating the Sectra Table into echocardiography training may improve the effectiveness of training programs.

The Use of Ultrasound Simulators to Strengthen Scanning Skills in Medical Students: A Randomized Controlled Trial.

OBJECTIVES: This study evaluates the use of ultrasound simulators for retaining and improving ultrasound skills acquired in undergraduate ultrasound training. METHODS: Fourth-year medical students (n = 19) with prior training in point-of-care sonography for shock assessment were recruited for this study. Students were randomly assigned to a study group (n = 10) that followed an undergraduate ultrasound training curriculum, then used a simulator to complete 2 self-directed practice ultrasound sessions over 4 weeks. The control group (n = 9) followed the same undergraduate ultrasound training curriculum and received no additional access to a simulator or ultrasound training. A blinded assessment of the students was performed before and after the 4-week study period to evaluate their image acquisition skills on standardized patients (practical examination). To evaluate the student's clinical understanding of pathological ultrasound images, students watched short videos of prerecorded ultrasound scans and were asked to complete a 22-point questionnaire to identify their findings (visual examination). RESULTS: All results were adjusted to pretest performance. The students in the study group performed better than those in the control group on the visual examination (80.1% versus 58.9%; P = .003) and on the practical examination (77.7% versus 57.0%; P = .105) after the 4-week study period. The score difference on the postintervention practical examinations was significantly better for the study group compared to the control group (11.6% versus -9.9%; P = .0007). CONCLUSION: The use of ultrasound simulators may be a useful tool to help previously trained medical students retain and improve point-of-care ultrasound skills and knowledge.

Ultrasonic aspiration in neurosurgery: comparative analysis of complications and outcome for three commonly used models.

INTRODUCTION: Ultrasonic aspiration (UA) devices are commonly used for resecting intracranial tumors, as they allow for internal debulking of large tumors, hereby avoiding damage to adjacent brain tissue during the dissection. Little is known about their comparative safety profiles. METHODS AND MATERIALS: We analyzed data from a prospective patient registry. Procedures using one of the following UA models were included: Integra® CUSA, Söring®, and Stryker® Sonopet. The primary endpoint was morbidity at discharge, defined as significant worsening on the Karnofsky Performance Scale. Secondary endpoints included morbidity and mortality until 3 months postoperative (M3), occurrence, type, and etiology of complications. RESULTS: Of n = 1028 procedures, the CUSA was used in n = 354 (34.4 %), the Söring in n = 461 (44.8 %), and the Sonopet in n = 213 (20.7 %). There was some heterogeneity of study groups. In multivariable analysis, patients in the Söring (adjusted odds ratio (aOR) 1.29; 95 % confidence interval (CI), 0.80-2.08; p = 0.299), and Sonopet group (aOR, 0.86; 95 % CI, 0.46-1.61; p = 0.645) were as likely as patients in the CUSA group to experience discharge morbidity. At M3, patients in the Söring (aOR, 1.20; 95 % CI, 0.78-1.86; p = 0.415) and Sonopet group (aOR, 0.53; 95 % CI, 0.26-1.08; p = 0.080) were as likely as patients in the CUSA group to experience morbidity. There were also no differences for M3 morbidity in subgroup analyses for gliomas, meningiomas, and metastases. The grade (p = 0.608) and etiology (p = 0.849) of postoperative complications were similar. CONCLUSIONS: Neurosurgeons select UA types with regard to certain case-specific characteristics. The safety profiles of three commonly used UA types appear mostly similar.