Estimating the global prevalence of transthyretin familial amyloid polyneuropathy.

INTRODUCTION: This study sought to estimate the global prevalence of transthyretin familial amyloid polyneuropathy (ATTR-FAP). METHODS: Prevalence estimates and information supporting prevalence calculations was extracted from records yielded by reference-database searches (2005-2016), conference proceedings, and nonpeer reviewed sources. Prevalence was calculated as prevalence rate multiplied by general population size, then extrapolated to countries without prevalence estimates but with reported cases. RESULTS: Searches returned 3,006 records; 1,001 were fully assessed and 10 retained, yielding prevalence for 10 "core" countries, then extrapolated to 32 additional countries. ATTR-FAP prevalence in core countries, extrapolated countries, and globally was 3,762 (range 3639-3884), 6424 (range, 1,887-34,584), and 10,186 (range, 5,526-38,468) persons, respectively. DISCUSSION: The mid global prevalence estimate (10,186) approximates the maximum commonly accepted estimate (5,000-10,000). The upper limit (38,468) implies potentially higher prevalence. These estimates should be interpreted carefully because contributing evidence was heterogeneous and carried an overall moderate risk of bias. This highlights the requirement for increasing rare-disease epidemiological assessment and clinician awareness. Muscle Nerve 57: 829-837, 2018.

Treadmill associated head injuries on the rise: an 18 year review of U.S. emergency room visits.

OBJECTIVE: The treadmill is the most commonly used aerobic exercise equipment with studies showing many gym-related injuries are attributed to treadmills. The purpose of this study is to examine the incidence of treadmill-associated head injuries within the US. METHODS: Retrospective data from 1997 to 2014 was collected via the National Electronic Injury Surveillance System, which provides annual es7timates of injuries associated with consumer products. Patients over 18 years who sustained treadmill-associated head injuries were included, and the estimated annual incidence was determined. RESULTS: An estimated 4929 patients presented to US emergency departments with a head injury while exercising on a treadmill between 1997 and 2014. A >1000% increase in the number of head injuries was observed over the study period (p-value <0.001). Patients over 50 had a 14 times greater risk of admission than younger patients (p-value <0.001). Injuries were greater in women than men. CONCLUSION: Our study demonstrates a significant increase treadmill-associated head injuries from 1997 to 2014. This phenomenon is most pronounced in older and female populations. The exact etiology of this large increase remains unclear. Education on the proper use of treadmills as well as further investigation into the cause of the increase are warranted.

Electronic detectors for electron microscopy.

Due to the increasing popularity of electron cryo-microscopy (cryoEM) in the structural analysis of large biological molecules and macro-molecular complexes and the need for simple, rapid and efficient readout, there is a persuasive need for improved detectors. Commercial detectors, based on phosphor/fibre optics-coupled CCDs, provide adequate performance for many applications, including electron diffraction. However, due to intrinsic light scattering within the phosphor, spatial resolution is limited. Careful measurements suggest that CCDs have superior performance at lower resolution while all agree that film is still superior at higher resolution. Consequently, new detectors are needed based on more direct detection, thus avoiding the intermediate light conversion step required for CCDs. Two types of direct detectors are discussed in this review. First, there are detectors based on hybrid technology employing a separate pixellated sensor and readout electronics connected with bump bonds-hybrid pixel detectors (HPDs). Second, there are detectors, which are monolithic in that sensor and readout are all in one plane (monolithic active pixel sensor, MAPS). Our discussion is centred on the main parameters of interest to cryoEM users, viz. detective quantum efficiency (DQE), resolution or modulation transfer function (MTF), robustness against radiation damage, speed of readout, signal-to-noise ratio (SNR) and the number of independent pixels available for a given detector.

Spectroscopic characterization of a novel electronic brachytherapy system.

The Axxent developed by Xoft Inc. is a novel electronic brachytherapy system capable of generating x-rays up to 50 keV. These low energy photon-emitting sources merit attention not only because of their ability to vary the dosimetric properties of the radiation, but also because of the radiobiological effects of low energy x-rays. The objective of this study is to characterize the x-ray source and to model it using the Geant4 Monte Carlo code. Spectral and attenuation curve measurements are performed at various peak voltages and angles and the source is characterized in terms of spectrum and half-value layers (HVLs). Also, the effects of source variation and source aging are quantified. Bremsstrahlung splitting, phase-space scoring and particle-tagging features are implemented in the Geant4 code, which is bench-marked against BEAMnrc simulations. HVLs from spectral measurements, attenuation curve measurements and Geant4 simulations mostly agree within uncertainty. However, there are discrepancies between measurements and simulations for photons emitted on the source transverse plane (90 degrees).

Accuracy of electronic apex locator in length determination in the presence of different irrigants: An in vitro study.

Determining the root canal length accurately had been a challenge in endodontics. Introduction of apex locators have definitely served as an effective adjuvant to radiographs. This in vitro study had attempted to compare the effectiveness of electronic apex locator in the presence of various canal contents. Comparison of the length determined by apex locators with the radiographic length was also made. The results of the study had shown that the length of root canals can be accurately made irrespective of the canal contents.

Primary Salvage Survey of the Interference of Radiowaves Emitted by Smartphones on Medical Equipment.

Use of mobile phones has become a standard reality of everyday living for many people worldwide, including medical professionals, as data sharing has drastically helped to improve quality of care. This increase in the use of mobile phones within hospitals and medical facilities has raised concern regarding the influence of radio waves on medical equipment. Although comprehensive studies have examined the effects of electromagnetic interference from 2G wireless communication and personal digital cellular systems on medical equipment, similar studies on more recent wireless technologies such as Long Term Evolution, wideband code division multiple access, and high-speed uplink access have yet to be published. Numerous tests targeting current wireless technologies were conducted between December 2012 and March 2013 in an anechoic chamber, shielded from external radio signals, with a dipole antenna to assess the effects of smartphone interference on several types of medical equipment. The interference produced by electromagnetic waves across five frequency bands from four telecommunication standards was assessed on 49 components from 22 pieces of medical equipment. Of the 22 pieces of medical equipment tested, 13 experienced interference at maximum transmission power. In contrast, at minimum transmission power, the maximum interference distance varied from 2 to 5 cm for different wireless devices. Four machines were affected at the minimum transmission power, and the maximum interference distance at the maximum transmission power was 38 cm. Results show that the interference from smartphones on medical equipment is very controllable.

The accuracy of a handheld portable spirometer.

BACKGROUND: Objective measurement of lung function is considered essential in the management of patients with asthma and COPD. Many primary care practitioners lack the means necessary to obtain these measurements conveniently. To meet this need, electronic spirometers, offering portability, ease of operation, and timesaving readout options have been introduced. We compared the accuracy of a typical pneumotachograph-based device with a conventional volume displacement spirometer. METHODS: We compared indexes of pulmonary function (FVC, FEV1, mean forced expiratory flow during the middle half of FVC, [FEF25-75%], and peak expiratory flow rate [PEFR]) measured by the handheld device with those measured by a conventional spirometer in 75 white subjects (33 men, 42 women) with a median age of 43 years (22 to 77 years) who were either healthy or were referred to the pulmonary function laboratory of a large tertiary care teaching hospital. The order of the instrument tested first was randomized and the patients were blinded to which instrument was being studied. RESULTS: There was a linear relationship between instruments for all indexes measured (r = 0.97, 0.98, 0.94, 0.94 for FVC, FEV1, FEF25-75%, and PEFR, respectively, for all p < 0.001). The random error (precision) was within 5% only for FEV1. The mean of the differences between the values obtained using both instruments (the bias) +/- limits of agreement (+/- 2 SD) were 0.06 +/- 0.56 L for FVC (p = NS), 0.2 +/- 0.44 L for FEV1 (p < 0.05), 0.61 +/- 1.26 L/s for FEF25-75% (p < 0.05), and 0.44 +/- 1.9 L/s for PEFR (p < 0.05). CONCLUSION: Our data suggest that measurements obtained using the pneumotachograph device are closely related to those obtained by volume displacement spirometry and that the handheld device may be useful in clinical practice. However, because the limits of agreement are wide and the difference between the two instrument measurements are significant for FEV1, FEF25-75%, and PEFR, the bias between them is not consistent nor is it insignificant. Therefore, the measurements made with the two types of machine cannot be used interchangeably.

Study of erythrocyte sedimentation behavior by piezoelectric crystal impedance sensor.

Based on the impedance characteristic of erythrocytes at high frequency, the response of piezoelectric crystal impedance (PCI) sensor in the erythrocyte suspension was derived and verified experimentally. A method of using PCI sensor to investigate erythrocyte aggregation-sedimentation phenomenon was proposed. From the frequency response of the PCI sensor, the erythrocyte aggregation time and sedimentation rate could be obtained during erythrocyte aggregation and sedimentation. With the present method, the effects of the erythrocyte deformability, the osmotic pressure and the coexisting macromolecules on the erythrocyte sedimentation rate were studied. The results show that the PCI sensor possesses some advantages, such as good sensitivity, simplicity of use and no thermal effect for the impedance study of erythrocyte aggregation and sedimentation.

Development of a microcontroller-based automatic control system for the electrohydraulic total artificial heart.

An automatic physiological control system for the actively filled, alternately pumped ventricles of the volumetrically coupled, electrohydraulic total artificial heart (EHTAH) was developed for long-term use. The automatic control system must ensure that the device: 1) maintains a physiological response of cardiac output, 2) compensates for an nonphysiological condition, and 3) is stable, reliable, and operates at a high power efficiency. The developed automatic control system met these requirements both in vitro, in week-long continuous mock circulation tests, and in vivo, in acute open-chested animals (calves). Satisfactory results were also obtained in a series of chronic animal experiments, including 21 days of continuous operation of the fully automatic control mode, and 138 days of operation in a manual mode, in a 159-day calf implant.

Effect of an imaging-based streamlined electronic healthcare process on quality and costs.

RATIONALE AND OBJECTIVES: A streamlined process of care supported by technology and imaging may be effective in managing the overall healthcare process and costs. This study examined the effect of an imaging-based electronic process of care on costs and rates of hospitalization, emergency room (ER) visits, specialist diagnostic referrals, and patient satisfaction. MATERIALS AND METHODS: A healthcare process was implemented for an employer group, highlighting improved patient access to primary care plus routine use of imaging and teleconsultation with diagnostic specialists. An electronic infrastructure supported patient access to physicians and communication among healthcare providers. The employer group, a self-insured company, manages a healthcare plan for its employees and their dependents: 4,072 employees were enrolled in the test group, and 7,639 in the control group. Outcome measures for expenses and frequency of hospitalizations, ER visits, traditional specialist referrals, primary care visits, and imaging utilization rates were measured using claims data over 1 year. Homogeneity tests of proportions were performed with a chi-square statistic, mean differences were tested by two-sample t-tests. Patient satisfaction with access to healthcare was gauged using results from an independent firm. RESULTS: Overall per member/per month costs post-implementation were lower in the enrolled population (126 dollars vs 160 dollars), even though occurrence of chronic/expensive diseases was higher in the enrolled group (18.8% vs 12.2%). Lower per member/per month costs were seen for inpatient (33.29 dollars vs 35.59 dollars); specialist referrals (21.36 dollars vs 26.84 dollars); and ER visits (3.68 dollars vs 5.22 dollars). Moreover, the utilization rate for hospital admissions, ER visits, and traditional specialist referrals were significantly lower in the enrolled group, although primary care and imaging utilization were higher. Comparison to similar employer groups showed that the company's costs were lower than national averages (119.24 dollars vs 146.32 dollars), indicating that the observed result was not attributable to normalization effects. Patient satisfaction with access to healthcare ranked in the top 21st percentile. CONCLUSION: A streamlined healthcare process supported by technology resulted in higher patient satisfaction and cost savings despite improved access to primary care and higher utilization of imaging.

Evaluation of electronic databases used to identify solid oral dosage forms.

The ability of electronic drug identification databases to identify solid oral dosage forms by their imprint codes was studied. The following seven commercially available electronic drug identification databases were selected to identify 500 solid oral dosage forms by their imprint codes: Clinical Pharmacology (Gold Standard Media, Tampa, FL), eFacts (Facts and Comparison, St. Louis, MO), Ident-A-Drug (Therapeutic Research, Stockton, CA), Identidex (Micromedex, Greenwood Village, CO), Clinical Reference Library (Lexi-Comp, Hudson, OH), Physicians' Desk Reference (PDR) Electronic Library (Medical Economics, Montvale, NJ), and RxList (RxList LLC, San Francisco, CA), Chi-square test was used to compare the percentages of medications identified by each of the seven electronic references. The ability of the databases to identify medication by specific characteristics, such as brand name versus generic, prescription versus nonprescription, commercially available for more than one year versus less than one year, colored versus white drug products, and controlled versus noncontrolled substances was evaluated. A logistic regression model was used to determine the probability of a drug product being identified by one of the electronic references based on these characteristics. All seven electronic databases combined identified 95.6% of the unknown medications by imprint code, color, shape, and scoring. Ident-A-Drug and Identidex identified the most drugs. The PDR Electronic Library and Facts and Comparisons Identified the least number of drugs. Solid oral dosage forms more likely to be identified were those that were on the market for more than a year, brand-name products, and prescription medications. Generic products on the market for less than a year and nonprescription products were particularly difficult to identify. A combination of electronic drug identification databases provides the best method of drug identification in an institutional setting.

Use of diagnostic ultrasound, X-ray examinations, and electronic fetal monitoring in perinatal medicine.

Obstetrical technologies such as electronic fetal monitoring (EFM) and selected diagnostic imaging procedures can be integral components of perinatal care. The Center for Devices and Radiological Health, a unit within the Food and Drug Administration, collaborated with the National Center for Health Statistics in the design and conduct of a National Maternal and Infant Health Survey to collect information from prenatal care providers, hospitals, and mothers on the use of EFM, diagnostic ultrasound, and x-ray examinations during pregnancy, labor, and delivery. A pretest, conducted some months before the survey began, showed that 78.8% of the pregnancies surveyed received a diagnostic ultrasound examination during pregnancy. Approximately 58.3% of the ultrasound-exposed mothers had two or more such examinations. Approximately 10.1% of the ultrasound examinations were performed in the first trimester of pregnancy, 57.0% in the second trimester, and 32.9% in the third trimester. The most common indication for an ultrasound examination was to establish dates or gestational age. Approximately 15.3% of the pregnancies surveyed received an x-ray examination. Approximately 74.6% of the pregnancies were monitored with EFM during labor. External EFM was used alone during 54.9% of the labors and along with internal EFM during 19.7% of the labors. The implications of these pretest findings are discussed, along with a review of the medical literature on the safety and effectiveness of these medical device technologies.

EIT data noise evaluation in the clinical environment.

In the clinical environment the reliable interpretation of EIT images depends on the quality of the data. In the electrically noisy hospital environment the system performance needs to be assessed for each clinical investigation. From the model of noise presented, a figure of merit for comparisons of system performance with a known standard, or with previous studies, can be generated. The method depends on calculating the variances of the differences in reciprocity measurements as a function of the distance between the current drive electrodes and the receive voltage electrodes. These measurements fit the noise model, with minimal interference from physiological variability, and permit a figure of merit to be calculated which is a representation of the noise at the point to the system. Typical figures of merit are 7.36 +/- 0.03 microV for a test card and 10.50 +/- 16 microV for subject data.

A multifrequency serial EIT system.

A multifrequency (1 kHz-1 MHz) serial electrical impedance tomography (EIT) system has been developed. It is based on 16 active electrodes and can be extended up to 32. Each active electrode can be programmed for current driving and for measuring either the injected current or the voltage difference between adjacent electrodes, and includes calibration facilities. Real and imaginary parts of the impedance are obtained by applying a parametric identification method (extended Prony), but other techniques are easily adaptable. Image reconstruction is carried out using the Sheffield filtered back-projection algorithm. Characteristic frequency images are under development and should be of great interest to distinguish between normal and tumorous tissues.

An interleaved drive electrical impedance tomography image reconstruction algorithm.

In this study, a reconstruction algorithm for a 16-electrode interleaved-drive electrical impedance tomography (EIT) system is developed, based on inversion of an analytically calculated sensitivity matrix. The sensitivity matrix is calculated using Geselowitz's lead-sensitivity theorem. Eight interleaved electrodes out of 16 (equally spaced) electrodes are designated as current injection electrodes and the remaining eight electrodes are designated as measurement electrodes. The sensitivity matrix is singular, therefore singular value decomposition (SVD) of the sensitivity matrix, followed by pseudoinversion-with and without truncation-is used to reconstruct images. The algorithm is a single-pass algorithm. Data from a saline filled tank and in vivo data during respiration and the cardiac cycle, acquired by using a Sheffield multifrequency system, are used to reconstruct images. The effect of different truncation levels on the reconstructed images is investigated.

Three-dimensional image reconstruction for electrical impedance tomography.

Very little work has been conducted on three-dimensional aspects of electrical impedance tomography (EIT), partly due to the increased computational complexity over the two-dimensional aspects of EIT. Nevertheless, extending EIT to three-dimensional data acquisition and image reconstruction may afford significant advantages such as an increase in the size of the independent data set and improved spatial resolution. However, considerable challenges are associated with the software aspects of three-dimensional EIT systems due to the requirement for accurate three-dimensional forward problem modelling and the derivation of three-dimensional image reconstruction algorithms. This paper outlines the work performed to date to derive a three-dimensional image reconstruction algorithm for EIT based on the inversion of the sensitivity matrix approach for a finite right circular cylinder. A comparison in terms of the singular-value spectra and the singular vectors between the sensitivity matrices for a three-dimensional cylinder and a two-dimensional disc has been performed. This comparison shows that the three-dimensional image reconstruction algorithm recruits more central information at lower condition numbers than the two-dimensional image reconstruction algorithm.

Penalty methods for the inverse problem in EIT.

The conductivity profiles arising in medical applications of electrical impedance tomography (EIT) are often of 'blocky' structure, i.e. they are relatively constant inside an organ and are rapidly varying at its boundary. Standard regularization methods for the inverse problem tend to blur these sharply defined edges. A penalty method is proposed which is especially designed for a better reconstruction of discontinuous conductivity profiles.

Optimal filtering of EIT data in spectral expansion analysis.

The signal-to-noise rations for some EIT measurements are very low, and for in vivo EIT measurements these are dependent on the electrode positioning and the distance from the current drive. The effect of removing noisy measurements to produce higher-fidelity images was investigated for the case of gastric emptying data. A consequence of this filtering was the reduction in the size of the sensitivity matrix and its subsequent singular-value decomposition. Several different filters were tested and for each of these spectral expansion regularization filter was optimized using a chi 2 test. Filtering out the measurement made by the spinal electrode, where the spinal bone barrier lies directly in the current path to the stomach, produced improved images by reducing the artefact content in the spinal sector of the conductivity map. For stomach imaging little useful information is produced by the spinal electrode, and the benefits of filtering dominate. However artefact images may be generated. In contrast consistent small improvements were produced by filtering out some of the weakest signals.

Some boundary problems in electrical impedance tomography.

Accurate mathematical modelling is important in the development of iterative image reconstruction algorithms for electrical impedance tomography (EIT). In such schemes the forward problem of calculating the electric potential from Neumann boundary data is solved many times. One aspect of this problem which has received some attention is the mathematical modelling of the electrodes used in the technique. In this paper we describe an integral equation formulation of a boundary value problem associated with this tissue and we indicate some of the ways in which this formulation can be used to obtain numerical and analytic results.

Improvement of the positional accuracy of EIT images of the head using a Lagrange multiplier reconstruction algorithm with diametric excitation.

A novel algorithm for the reconstruction of dynamic images using diametric excitation has been developed. The algorithm is specifically designed to image impedance changes in the brain using boundary data obtained from scalp electrodes by incorporating a priori information. The a priori information is obtain by solving the forward problem using a finite-element model (FEM) which includes the discontinuity of the skull resistivity. The advantages with this new approach are that the sensitivity and accuracy of the location of the impedance changes are improved compared to methods based on adjacent excitation.