Ultrasound-Guided Serratus Anterior Plane Block (SAPB) Improves Pain Control in Patients With Rib Fractures.

OBJECTIVES: The serratus anterior plane block (SAPB) is an ultrasound-guided compartment block; limited data suggest that it can decrease pain in patients with rib fractures or chest wall pain. We sought to determine the effect of SAPB on pain and incentive spirometry (IS) maximal vital capacity in adult patients with rib fractures. METHODS: We enrolled a prospective sample of adult patients with at least two unilateral rib fractures who were being admitted for pain control. SAPB was performed by trained emergency physicians. Patients reported pain on an 11-point Numeric Rating Scale at rest and during IS, before, 15, and 60 minutes after SAPB. RESULTS: Mean pain scores decreased by 1.8 (SD 2.17, 95% confidence interval [CI]: 0.79-2.81) at 15 minutes and 2.5 (SD 2.69, 95% CI: 1.24-3.76) at 60 minutes. Compared to pre-block pain scores during IS, mean pain scores decreased by 1.95 (SD 1.99, 95% CI: 1.02-2.88) at 15 minutes and 2.4 (SD 2.42, 95% CI: 1.27-3.53) at 60 minutes. Mean maximum vital capacity increased by 232 mL (SD 406, 95% CI: 36-427) at 60 minutes. Zero SAPB-attributable complications were identified in the 24 hours post-enrollment. CONCLUSIONS: In patients with multiple rib fractures, SAPB reduced pain scores at rest and during IS, and increased maximal vital capacity. The SABP may be a safe and effective modality for pain control in trauma patients with multiple rib fractures.

Growth and globalization of point-of-care ultrasound publications in emergency medicine.

OBJECTIVES: Since the introduction of point-of-care ultrasound (POCUS) in emergency medicine (EM), the applications, indications, and training for POCUS have grown. POCUS training in EM residency is standard and POCUS fellowships are common. We sought to quantify and characterize changes in POCUS publications over time with a scoping review of the literature METHODS: We conducted a structured keyword search of high impact EM journals according to 2019 journal citation reports and other journals publishing POCUS studies between 2000-2019. Two abstractors recorded whether the publication was POCUS related, the type of publication, and author affiliation by department and country. We included studies with at least one author affiliated with a department of EM. Agreement between abstractors was tested. RESULTS: The number of POCUS-related publications grew from a mean of 8.8 publications/year 2000-2004 to 134.8 publications/year from 2015-2019. The most common publication type was case reports or series (44%). The proportion of publications from outside the United States (US) decreased over time. Between 2000 and 2004 89% of publications came from authors affiliated with US institutions; from 2015-2019 this had decreased to 64%. Agreement between abstractors was excellent (Cohen's k = 0.89) CONCLUSIONS: POCUS publications increased substantially between 2000-2019. The most common type of publication was a case report, which was consistent throughout the study period. Authorship from outside the US increased. Publications yielding high-quality evidence from observational or controlled studies represented a low proportion of the total number of studies.

Wafer-scale graphene quality assessment using micro four-point probe mapping.

Micro four-point probes (M4PP) provide rapid and automated lithography-free transport properties of planar surfaces including two-dimensional materials. We perform sheet conductance wafer maps of graphene directly grown on a 100 mm diameter SiC wafer using a multiplexed seven-point probe with minor additional measurement time compared to a four-point probe. Comparing the results of three subprobes we find that compared to a single-probe result, our measurement yield increases from 72%-84% to 97%. The additional data allows for correlation analysis between adjacent subprobes, that must measure the same values in case the sample is uniform on the scale of the electrode pitch. We observe that the relative difference in measured sheet conductance between two adjacent subprobes increase in the transition between large and low conductance regions. We mapped sheet conductance of graphene as it changed over several weeks. Terahertz time-domain spectroscopy conductivity maps both before and after M4PP mapping showed no significant change due to M4PP measurement, with both methods showing the same qualitative changes over time.

Test performance of point-of-care ultrasound for gastric content.

OBJECTIVE: We sought to determine test performance characteristics of emergency physician ultrasound for the identification of gastric contents. METHODS: Subjects were randomized to fast for at least 10 h or to consume food and water. A sonologist blinded to the patient's status performed an ultrasound of the stomach 10 min after randomization and oral intake, if applicable. The sonologist recorded their interpretation of the study using three sonographic windows. Subsequently 2 emergency physicians reviewed images of each study and provided an interpretation of the examination. Test performance characteristics and inter-rater agreement were calculated. RESULTS: 45 gastric ultrasounds were performed. The sonologist had excellent sensitivity (92%; 95% CI 73%-99%) and specificity (85%; 95% CI 62%-92%). Expert review demonstrated excellent sensitivity but lower specificity. Inter-rater agreement was very good (κ = 0.64, 95%CI 0.5-0.78). CONCLUSION: Emergency physician sonologists were sensitive but less specific at detecting stomach contents using gastric ultrasound.

WAMAMI: emergency physicians can accurately identify wall motion abnormalities in acute myocardial infarction.

OBJECTIVE: The ability to identify wall motion abnormalities may be useful for emergency clinicians, but is not typically evaluated in point-of-care echocardiograms. We sought to determine if emergency physicians with basic training in emergency echocardiography could identify regional wall motion abnormalities (RWMA) in patients admitted with ST-elevation myocardial infarction (STEMI). METHODS: We prospectively enrolled patients with admitted with STEMI. Resident physicians with basic training in emergency ultrasound, blinded to other patient data, performed a point-of-care echocardiogram to evaluate for RWMA. If present, they also recorded the suspected territory of the RWMA. We calculated test performance characteristics and compared the agreement between point-of-care and comprehensive echocardiogram for RWMA and territory. RESULTS: 75 patients with STEMI were enrolled, and 62% had a RMWA. RWMA were identified with excellent test performance characteristics (sensitivity 88% (95% CI 75-96); specificity 92% (95% CI 75-99)). There was substantial agreement between the point-of-care echocardiogram and reference standard (K = 0.79; 95% CI: 0.64-0.94). CONCLUSIONS: Emergency physicians with core training in point-of-care echocardiography can accurately identify RMWA.

Scalable and Tunable Periodic Graphene Nanohole Arrays for Mid-Infrared Plasmonics.

Despite its great potential for a wide variety of devices, especially mid-infrared biosensors and photodetectors, graphene plasmonics is still confined to academic research. A major reason is the fact that, so far, expensive and low-throughput lithography techniques are needed to fabricate graphene nanostructures. Here, we report for the first time a detailed experimental study on electrostatically tunable graphene nanohole array surfaces with periods down to 100 nm, showing clear plasmonic response in the range ∼1300-1600 cm-1, which can be fabricated by a scalable nanoimprint technique. Such large area plasmonic nanostructures are suitable for industrial applications, for example, surface-enhanced infrared absorption (SEIRA) sensing, as they combine easy design, extreme field confinement, and the possibility to excite multiple plasmon modes enabling multiband sensing, a feature not readily available in nanoribbons or other localized resonant structures.

Conductivity mapping of graphene on polymeric films by terahertz time-domain spectroscopy.

Fast inline characterization of the electrical properties of graphene on polymeric substrates is an essential requirement for quality control in industrial graphene production. Here we show that it is possible to measure the sheet conductivity of graphene on polymer films by terahertz time-domain spectroscopy (THz-TDS) when all internally reflected echoes in the substrate are taken into consideration. The conductivity measured by THz-TDS is comparable to values obtained from four point probe measurements. THz-TDS maps of 25x30 cm2 area graphene films were recorded and the DC conductivity and carrier scattering time were extracted from the measurements. Additionally, the THz-TDS conductivity maps highlight tears and holes in the graphene film, which are not easily visible by optical inspection.

Quality assessment of terahertz time-domain spectroscopy transmission and reflection modes for graphene conductivity mapping.

We present a comparative study of electrical measurements of graphene using terahertz time-domain spectroscopy in transmission and reflection mode, and compare the measured sheet conductivity values to electrical van der Pauw measurements made independently in three different laboratories. Overall median conductivity variations of up to 15% were observed between laboratories, which are attributed mainly to the well-known temperature and humidity dependence of non-encapsulated graphene devices. We conclude that terahertz time-domain spectroscopy performed in either reflection mode or transmission modes are indeed very accurate methods for mapping electrical conductivity of graphene, and that both methods are interchangeable within measurement uncertainties. The conductivity obtained via terahertz time-domain spectroscopy were consistently in agreement with electrical van der Pauw measurements, while offering the additional advantages associated with contactless mapping, such as high throughput, no lithography requirement, and with the spatial mapping directly revealing the presence of any inhomogeneities or isolating defects. The confirmation of the accuracy of reflection-mode removes the requirement of a specialized THz-transparent substrate to accurately measure the conductivity.

Carotid Flow Time Test Performance for the Detection of Dehydration in Children With Diarrhea.

OBJECTIVES: Unstructured clinical assessments of dehydration in children are inaccurate. Point-of-care ultrasound is a noninvasive diagnostic tool that can help evaluate the volume status; the corrected carotid artery flow time has been shown to predict volume depletion in adults. We sought to determine the ability of the corrected carotid artery flow time to identify dehydration in a population of children presenting with acute diarrhea in Dhaka, Bangladesh. METHODS: Children presenting with acute diarrhea were recruited and rehydrated according to hospital protocols. The corrected carotid artery flow time was measured at the time of presentation. The percentage of weight change with rehydration was used to categorize each child's dehydration as severe (>9%), some (3%-9%), or none (<3%). A receiver operating characteristic curve was constructed to test the performance of the corrected carotid artery flow time for detecting severe dehydration. Linear regression was used to model the relationship between the corrected carotid artery flow time and percentage of dehydration. RESULTS: A total of 350 children (0-60 months) were enrolled. The mean corrected carotid artery flow time was 326 milliseconds (interquartile range, 295-351 milliseconds). The area under the receiver operating characteristic curve for the detection of severe dehydration was 0.51 (95% confidence interval, 0.42, 0.61). Linear regression modeling showed a weak association between the flow time and dehydration. CONCLUSIONS: The corrected carotid artery flow time was a poor predictor of severe dehydration in this population of children with diarrhea.

Point-of-Care Ultrasound Use, Accuracy, and Impact on Clinical Decision Making in Rwanda Hospitals.

OBJECTIVES: Few studies of point-of-care ultrasound training and use in low resource settings have reported the impact of examinations on clinical management or the longer-term quality of trainee-performed studies. We characterized the long-term effect of a point-of-care ultrasound program on clinical decision making, and evaluated the quality of clinician-performed ultrasound studies. METHODS: We conducted point-of-care ultrasound training for physicians from Rwandan hospitals. Physicians then used point-of-care ultrasound and recorded their findings, interpretation, and effects on patient management. Data were collected for 6 months. Trainee studies were reviewed for image quality and accuracy. RESULTS: Fifteen participants documented 1158 ultrasounds; 590 studies (50.9%) had matched images and interpretations for review. Abdominal ultrasound for free fluid was the most frequently performed application. The mean image quality score was 2.36 (95% confidence interval, 2.28-2.44). Overall sensitivity and specificity for trainee-performed examinations was 94 and 98%. Point-of-care ultrasound use most commonly changed medications administered (42.4%) and disposition (30%). CONCLUSIONS: A point-of-care ultrasound training intervention in a low-resource setting resulted in high numbers of diagnostic-quality studies over long-term follow-up. Ultrasound use routinely changed clinical decision making.

Intensive point-of-care ultrasound training with long-term follow-up in a cohort of Rwandan physicians.

OBJECTIVE: We delivered a point-of-care ultrasound training programme in a resource-limited setting in Rwanda, and sought to determine participants' knowledge and skill retention. We also measured trainees' assessment of the usefulness of ultrasound in clinical practice. METHODS: This was a prospective cohort study of 17 Rwandan physicians participating in a point-of-care ultrasound training programme. The follow-up period was 1 year. Participants completed a 10-day ultrasound course, with follow-up training delivered over the subsequent 12 months. Trainee knowledge acquisition and skill retention were assessed via observed structured clinical examinations (OSCEs) administered at six points during the study, and an image-based assessment completed at three points. RESULTS: Trainees reported minimal structured ultrasound education and little confidence using point-of-care ultrasound before the training. Mean scores on the image-based assessment increased from 36.9% (95% CI 32-41.8%) before the initial 10-day training to 74.3% afterwards (95% CI 69.4-79.2; P < 0.001). The mean score on the initial OSCE after the introductory course was 81.7% (95% CI 78-85.4%). The mean OSCE performance at each subsequent evaluation was at least 75%, and the mean OSCE score at the 58-week follow up was 84.9% (95% CI 80.9-88.9%). CONCLUSIONS: Physicians providing acute care in a resource-limited setting demonstrated sustained improvement in their ultrasound knowledge and skill 1 year after completing a clinical ultrasound training programme. They also reported improvements in their ability to provide patient care and in job satisfaction.

Terahertz wafer-scale mobility mapping of graphene on insulating substrates without a gate.

We demonstrate wafer-scale, non-contact mapping of essential carrier transport parameters, carrier mobility (µdrift), carrier density (Ns), DC sheet conductance (σdc), and carrier scattering time (τsc) in CVD graphene, using spatially resolved terahertz time-domain conductance spectroscopy. σdc and τsc are directly extracted from Drude model fits to terahertz conductance spectra obtained in each pixel of 10 × 10 cm2 maps with a 400 µm step size. σdc- and τsc-maps are translated into µdrift and Ns maps through Boltzmann transport theory for graphene charge carriers and these parameters are directly compared to van der Pauw device measurements on the same wafer. The technique is compatible with all substrate materials that exhibit a reasonably low absorption coefficient for terahertz radiation. This includes many materials used for transferring CVD graphene in production facilities as well as in envisioned products, such as polymer films, glass substrates, cloth, or paper substrates.