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The role for direct current cardioversion (DCCV) in the management of atrial fibrillation (AF) in the emergency department (ED) is unclear. Factors associated with DCCV in current practice are not well described, nor is the variation across patients and institutions. All ED encounters with a primary diagnosis of AF were identified from the Nationwide Emergency Department Sample from 2006 to 2017. The independent association of patient and hospital factors with use of DCCV was assessed using multivariable hierarchical logistic regression. The relative contributions of patient, hospital, and unmeasured hospital factors were assessed using reference effect measures methods. Among 1,280,914 visits to 3,264 EDs with primary diagnosis of AF, 31,422 patients (2.4%) underwent DCCV in the ED. History of stroke (odds ratio [OR] 0.14, 95% confidence interval [CI] 0.09 to 0.22, p <0.001) and dementia (OR 0.14, 95% CI 0.10 to 0.19, p <0.001) was associated with lowest odds of DCCV. Comparing patients more likely to receive DCCV (ninety-fifth percentile) with patients with median risk, the influence of unmeasured hospital factors (OR 14.13, 95% CI 12.55 to 16.09) exceeded the contributions of patient (OR 5.66, 95% CI 5.28 to 6.15) and measured hospital factors (OR 3.89, 95% CI 2.87 to 5.60). In conclusion, DCCV use in the ED varied widely across institutions. Disproportionately large unmeasured hospital variation suggests that presenting hospital is the most determinative factor in the use of DCCV for ED management of AF. Clarification is needed on best practices for management of AF in the ED, including the use of DCCV., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Unmanned aerial vehicles (UAVs) have become very popular tools for geoinformation acquisition in recent years. They have also been applied in many other areas of life. Their navigation is highly dependent on global navigation satellite systems (GNSS). The European Geostationary Navigation Overlay Service (EGNOS) is intended to support GNSSs during positioning, mainly for aeronautical applications. The research presented in this paper concerns the analysis of the positioning quality of a modified GPS/EGNOS algorithm. The calculations focus on the source of ionospheric delay data as well as on the aspect of smoothing code observations with phase measurements. The modifications to the algorithm concerned the application of different ionospheric models for position calculation. Consideration was given to the EGNOS ionospheric model, the Klobuchar model applied to the GPS system, the Klobuchar model applied to the BeiDou system, and the NeQuick model applied to the Galileo system. The effect of removing ionospherical corrections from GPS/EGNOS positioning on the results of the determination of positioning quality was also analysed. The results showed that the original EGNOS ionospheric model maintains the best accuracy results and a better correlation between horizontal and vertical results than the other models examined. The additional use of phase-smoothing of code observations resulted in maximum horizontal errors of approximately 1.3 m and vertical errors of approximately 2.2 m. It should be noted that the results obtained have local characteristics related to the area of north-eastern Poland.

Objective: To assess the contribution of unknown institutional factors (contextual effects) in the de-implementation of cALND in women with breast cancer., Summary of Background Data: Women included in the National Cancer Database with invasive breast carcinoma from 2012 to 2016 that underwent upfront lumpectomy and were found to have a positive sentinel node., Methods: A multivariable mixed effects logistic regression model with a random intercept for site was used to determine the effect of patient, tumor, and institutional variables on the risk of cALND. Reference effect measureswere used to describe and compare the contribution of contextual effects to the variation in cALND use to that of measured variables., Results: By 2016, cALND was still performed in at least 50% of the patients in a quarter of the institutions. Black race, younger women and those with larger or hormone negative tumors were more likely to undergo cALND. However, the width of the 90% reference effect measures range for the contextual effects exceeded that of the measured site, tumor, time, and patient demographics, suggesting institutional contextual effects were the major drivers of cALND de-implementation. For instance, a woman at an institution with low-risk of performing cALND would have 74% reduced odds of havinga cALND than if she was treated at a median-risk institution, while a patient at a high-risk institution had 3.91 times the odds., Conclusion: Compared to known patient, tumor, and institutional factors, contextual effects had a higher contribution to the variation in cALND use., Competing Interests: The authors report no conflicts of interest., (Copyright © 2020 Wolters Kluwer Health, Inc. All rights reserved.)

The paper presents the results of research on improving the accuracy of aircraft positioning using RTK-OTF (Real Time Kinematic-On The Fly) technique in air navigation. The paper shows a new solution of aircraft positioning for the application of the differential RTK-OTF technique in air navigation. In particular, a new mathematical model is presented which makes it possible to determine the resultant position of an aircraft based on the solution for the method of least squares in a stochastic process. The developed method combines in the process of alignment of GPS (Global Positioning System) observations, three independent solutions of the aircraft position in OTF mode for geocentric coordinates XYZ of the aircraft. Measurement weights as a function of the vector length and the mean vector length error, respectively, were used in the calculations. The applied calculation method makes it possible to determine the resultant position of the aircraft with high accuracy: better than 0.039 m with using the measurement weight as a function of the vector length and better than 0.009 m with the measurement weight as a function of the mean error of the vector length, respectively. In relation to the classical RTK-OTF solution as a model of the arithmetic mean, the proposed method makes it possible to increase the accuracy of determination of the aircraft position by 45-46% using the measurement weight as a function of the vector length, and 86-88% using the measurement weight as a function of the mean error of the vector length, respectively. The obtained test results show that the developed method improves to significantly improve the accuracy of the RTK-OTF solution as a method for determining the reference position in air navigation.

Objective: To determine the effect of daily environmental conditions on skiing and snowboarding-related injury rates., Methods: Injury information was collected from a mountainside clinic at a large Colorado ski resort for the 2012/2013 through 2016/2017 seasons. Daily environmental conditions including snowfall, snow base depth, temperature, open terrain and participant visits were obtained from historical resort records. Snowpack and visibility information were obtained for the 2013/2014 through 2014/2015 seasons and included in a subanalysis. Negative binomial regression was used to estimate injury rate ratios (IRRs) and 95% CIs., Results: The overall injury rate among skiers and snowboarders was 1.37 per 1000 participant visits during 2012/2013 through 2016/2017. After adjustment for other environmental covariates, injury rates were 22% higher (IRR=1.22, 95% CI 1.14 to 1.29) on days with <2.5 compared with ≥2.5 cm of snowfall, and 14% higher on days with average temperature in the highest quartile (≥-3.1°C) compared with the lowest (<-10.6°C; IRR=1.14, 95% CI 1.03 to 1.26). Rates decreased by 8% for every 25 cm increase in snow base depth (IRR=0.92, 95% CI 0.88 to 0.95). In a subanalysis of the 2013/2014 and 2014/2015 seasons including the same covariates plus snowpack and visibility, only snowpack remained significantly associated with injury rates. Rates were 71% higher on hardpack compared with powder days (IRR=1.71, 95% CI 1.18 to 2.49) and 36% higher on packed powder compared with powder days (IRR 1.36, 95% CI 1.12 to 1.64)., Conclusions: Environmental conditions, particularly snowfall and snowpack, have a significant impact on injury rates. Injury prevention efforts should consider environmental factors to decrease injury rates in skiers and snowboarders., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2020. No commercial re-use. See rights and permissions. Published by BMJ.)

This paper presents the concept of precise navigation based on SBAS technology and CORS stations. In a kinematic test, three rover Global Positioning System (GPS) receivers, properly spaced relatively to each other, were used in order to estimate reliable and redundant GPS/EGNOS positions. Next, the Kalman filter was employed to give the final solution. It was proven that EGNOS positioning allows to obtain an accuracy in the range of about 0.5-1.5 m. The proposed solution involving the use of three mobile receivers and Kalman filtering allowed to reduce the 3D error to a level below 0.3 m. Such an accuracy was achieved using only GPS L1 code observations and EGNOS corrections. Additionally, a reliable monitoring of quality of GPS/EGNOS positioning in the test area based on CORS stations was presented.

Background: Despite limited indications, preoperative stress testing is often used prior to non-cardiac surgery. Patient-level analyses of stress testing and outcomes are limited by case mix and selection bias. Therefore, we sought to describe facility-level rates of preoperative stress testing for non-cardiac surgery, and to determine the association between facility-level preoperative stress testing and postoperative major adverse cardiac events (MACE)., Methods: We identified patients undergoing non-cardiac surgery within 2 years of percutaneous coronary intervention in the Veterans Affairs (VA) Health Care System, from 2004 to 2011, facility-level rates of preoperative stress testing and postoperative MACE (death, myocardial infarction (MI) or revascularisation within 30 days). We determined risk-standardised facility-level rates of stress testing and postoperative MACE, and the relationship between facility-level preoperative stress testing and postoperative MACE., Results: Among 29 937 patients undergoing non-cardiac surgery at 131 VA facilities, the median facility rate of preoperative stress testing was 13.2% (IQR 9.7%-15.9%; range 6.0%-21.5%), and 30-day postoperative MACE was 4.0% (IQR 2.4%-5.4%). After risk standardisation, the median facility-level rate of stress testing was 12.7% (IQR 8.4%-17.4%) and postoperative MACE was 3.8% (IQR 2.3%-5.6%). There was no correlation between risk-standardised stress testing and composite MACE at the facility level (r=0.022, p=0.81), or with individual outcomes of death, MI or revascularisation., Conclusions: In a national cohort of veterans undergoing non-cardiac surgery, we observed substantial variation in facility-level rates of preoperative stress testing. Facilities with higher rates of preoperative stress testing were not associated with better postoperative outcomes. These findings suggest an opportunity to reduce variation in preoperative stress testing without sacrificing patient outcomes., Competing Interests: Competing interests: JAV was supported by an NIH T32 training grant (HL0782) at the University of Colorado, Aurora, CO, while work was completed., (© Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.)

Veterans are often transferred from "spoke" Veterans Administration (VA) clinics or hospitals to "hub" tertiary VA hospitals for advanced inpatient care, but they face significant barriers to safe transitions home. The Transitions Nurse Program was developed as an intervention to address the unique needs of this population. A difference-in-differences (DiD) analysis was used to compare outcomes between 303 veterans enrolled in this program and veterans transferred from the same spoke sites to a second, similar tertiary VA hub. Veterans enrolled in the program had significantly increased rates of follow-up with their primary care clinic within 14 days of discharge (DiD estimate: 10.43%, 95% confidence interval = 1.20 to 19.66), and a trend toward fewer unplanned 30-day readmissions (DiD estimate: -6.9%, 95% confidence interval = -14.2 to 0.31%, P = .06). There were no significant differences in 30-day emergency department visits or costs. Lessons learned from this preliminary intervention can inform implementation at other VA and non-VA sites.

Background: Stenosis of saphenous vein grafts (SVGs) after coronary artery bypass grafting (CABG) is common and often requires percutaneous coronary interventions (PCI) for treatment. However, data for the effectiveness of drug-eluting stents (DES) versus bare-metal stents (BMS) in SVG-PCI are unclear., Objectives: This study sought to examine the association between DES versus BMS used during SVG PCI and clinical outcomes in the national Veterans Affairs integrated healthcare system., Methods: We studied a national cohort of 2,471 post-CABG veterans undergoing SVG-PCI between 2008 and 2011 at all Veterans Affairs hospitals and compared clinical outcomes of between those receiving DES and BMS. Clinical outcomes included procedural complications, myocardial infarction (MI), and all-cause mortality. Comparisons were made in a propensity-matched cohort using Cox proportional hazards regression models., Results: DES were used in 1,549 SVG-PCI patients (63%) and the use of DES increased progressively with each calendar year (50% in 2008 to 69% in 2011). Incidence of procedural complications was low and comparable in both groups (2.8% among BMS vs. 2.3% among DES patients; p = 0.54). During long-term (>2 years) follow-up, use of DES was associated with lower mortality than BMS (hazard ratio [HR]: 0.72; 95% confidence interval [CI]: 0.57 to 0.89) and similar rates of MI (HR: 0.94; 95% CI: 0.71 to 1.24) in the propensity-matched cohort., Conclusions: In a national cohort of veterans, we observed widespread and increasing use of DES during SVG-PCI. In long-term follow-up, compared with BMS, DES use was safe and effective in SVG-PCI patients., (Copyright © 2014 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

The intestine is the major route of excretion of endogenous zinc (Zn) and has a key role in maintaining Zn homeostasis. The principal objective of this paper is to provide an interpretative report of quantities of endogenous fecal Zn (EFZ) excreted by rural Guatemalan school children fed either normal or low phytate maize as their principal food staple. EFZ was measured by a Zn stable isotope technique. EFZ did not differ between control and low phytate maize groups. The overall EFZ (n = 53) was (mean +/- SD) 1.56 +/- 0.69 mg Zn/d or 0.07 +/- 0.03 mg Zn x kg body wt(-1) x d(-1). EFZ was not correlated with the quantity of Zn absorbed. The estimated EFZ at the level of absorption that matched the physiologic requirement (EFZ(PR)) did not differ from the above mean value. The EFZ(PR) of 0.07 +/- 0.03 mg Zn/kg body wt is twice the value currently used in the estimation of Dietary Reference Intakes. Supported by other recent childhood data, these results suggest that the current estimates of EFZ(PR) used in the calculation of Zn requirements for children are misleadingly low.

The exchangeable zinc pool (EZP) is the sum of the combined pools that exchange with zinc in the plasma within 48-72 h and is thought to be critical for zinc-dependent biological processes. The size of the EZP in adults has been found to be positively related to dietary zinc intake, daily absorbed zinc and fecal excretion of endogenous zinc. In this study, we examine data on EZP size in relation to variables of zinc homeostasis in normal infants on different feeding regimens. Data from 45 male infants who participated in one of four different studies contribute to the analysis. The feeding regimens include exclusive breastfeeding (n = 9; age, 2-5 mo); breastfeeding plus modest supplementation with cow's milk-based formula (n = 16; age, 3-4 mo); exclusive formula feeding (n = 4; age, 3-4 mo) and exclusive breastfeeding plus complementary foods (n =16; age, 7 mo). Fractional absorption was determined by fecal monitoring after oral administration of zinc-stable isotopes. Urine enrichment 4-8 d posttracer was used to determine endogenous fecal zinc (7-mo-old infants excepted) and EZP size. Univariate correlations and multivariate regression analyses were performed between EZP and age, weight, dietary zinc intake, fractional absorption, total absorbed zinc and endogenous fecal zinc. Results include no significant relationship between EZP size and age, body weight or fractional absorption but a positive relationship with daily absorbed zinc and endogenous fecal zinc excretion. We conclude that the amount of absorbed zinc is not tightly regulated, and that endogenous fecal zinc is dependent on and responsive to the zinc status of the organism.

Context: The ability to predict the use of blood components during surgery will improve the blood bank's ability to provide efficient service., Objective: Develop prediction models using preoperative risk factors to assess blood component usage during elective coronary artery bypass graft surgery (CABG)., Design: Eighty-three preoperative, multidimensional risk variables were evaluated for patients undergoing elective CABG-only surgery., Main Outcomes Measures: The study endpoints included transfusion of fresh frozen plasma (FFP), platelets, and red blood cells (RBC). Multivariate logistic regression models were built to assess the predictors related to each of these endpoints., Setting: Department of Veterans Affairs (VA) health care system., Patients: Records for 3034 patients undergoing elective CABG-only procedures; 1033 patients received a blood component transfusion during CABG., Results: Previous heart surgery and decreased ejection fraction were significant predictors of transfusion for all blood components. Platelet count was predictive of platelet transfusion and FFP utilization. Baseline hemoglobin was a predictive factor for more than 2 units of RBC. Some significant hospital variation was noted beyond that predicted by patient risk factors alone., Conclusions: Prediction models based on preoperative variables may facilitate blood component management for patients undergoing elective CABG. Algorithms are available to predict transfusion resources to assist blood banks in improving responsiveness to clinical needs. Predictors for use of each blood component may be identified prior to elective CABG for VA patients.

In order to understand the thermal processes occurring within a water target we carried out calculations of heat transfer of the beam energy absorbed from the target water to the target back wall, and compared them with the temperatures measured during irradiations. It was shown, by both the experimental results and the heat transfer calculations, that, at high beam currents, static small volume water targets have a working temperature at the boiling point of the target water. The heat transfer occurs only by movement of the water molecules generated by the boiling target water and not by heat conduction or free convection alone. There is no heat transfer arising from vaporization and reflux.