Insufflation-Free, Perianal Work Platform.

There is an ever increasing volume of colorectal surgery being performed endoscopically by anal access, as well as greater employment of robotics for these procedures. Intraluminal visualization for perianal operations is today dependent on insufflation of the bowel. When full-thickness resections above the peritoneal reflection become necessary, the peritoneal cavity becomes inflated, facilitating infection and necessitating general anesthesia and patient intubation. Our patented tool was originally envisioned to enable abdominal cavity access via a single 2cm port incision, suitable for insufflation-free laparoscopic surgery, under local anesthesia (e.g., cholecystectomy). On further consideration, this instrument was modified to be used for perianal colorectal surgery.

Distinguishing features of Parkinson's disease fallers based on wireless insole plantar pressure monitoring.

Postural instability is one of the most disabling motor signs of Parkinson's disease (PD) and often underlies an increased likelihood of falling and loss of independence. Current clinical assessments of PD-related postural instability are based on a retropulsion test, which introduces human error and only evaluates reactive balance. There is an unmet need for objective, multi-dimensional assessments of postural instability that directly reflect activities of daily living in which individuals may experience postural instability. In this study, we trained machine-learning models on insole plantar pressure data from 111 participants (44 with PD and 67 controls) as they performed simulated static and active postural tasks of activities that often occur during daily living. Models accurately classified PD from young controls (area under the curve (AUC) 0.99+/- 0.00), PD from age-matched controls (AUC 0.99+/- 0.01), and PD fallers from PD non-fallers (AUC 0.91+/- 0.08). Utilizing features from both static and active postural tasks significantly improved classification performances, and all tasks were useful for separating PD from controls; however, tasks with higher postural threats were preferred for separating PD fallers from PD non-fallers.

A Review of Kinematic Theories and Practices Compiled for Biomechanics Students and Researchers.

The topic of kinematics is fundamental to engineering and has a significant bearing on clinical evaluations of human movement. For those studying biomechanics, this topic is often overlooked in importance. The degree to which kinematic fundamentals are included in Biomedical engineering (BmE) curriculums is not consistent across programs and often foundational understandings are gained only after reading literature if a research or development project requires that knowledge. The purpose of this paper is to present the important theories and methods of kinematic analysis and synthesis that should be in the "toolbox" of students of biomechanics. Each topic is briefly presented accompanied by an example or two. Deeper learning of each topic is left to the reader, with the help of some sample references to begin that journey.

Dopamine replacement therapy normalizes reactive step length to postural perturbations in Parkinson's disease.

BACKGROUND: Postural instability is one of the most disabling motor symptoms of Parkinson's disease (PD) given its association with falls and loss of independence. Previous studies have assessed biomechanical measures of reactive stepping in response to perturbations, showing that individuals with PD exhibit inadequate postural responses to regain balance. RESEARCH QUESTION: Does dopamine replacement therapy normalize step length in response to balance perturbations? METHODS: In this study, we estimated reactive step length, to a postural perturbation, retrospectively from a dataset of frontal plane video using 2D motion tracking and direct linear transform methods. We compared two perturbation methods: support surface translation and shoulder pull (the clinical standard) in 14 individuals with PD and 13 without PD (on and off medication), with and without partial body weight support (BWS). The primary outcome was the length of the first step taken to regain balance after the perturbation analyzed with mixed effects ANOVA, with post hoc analysis of anteroposterior (AP) and mediolateral (ML) components. RESULTS: PD OFF medication exhibited shorter reactive step length compared to PD ON and compared to control groups for the surface translation perturbations, but no significant difference was observed for the shoulder pull perturbations. SIGNIFICANCE: Dopamine replacement therapy affects step length in response to perturbation more robustly for surface translations than for a pull by the shoulders.

Neural Networks With Gated Recurrent Units Reduce Glucose Forecasting Error due to Changes in Sensor Location.

BACKGROUND: Continuous glucose monitors (CGMs) have become important tools for providing estimates of glucose to patients with diabetes. Recently, neural networks (NNs) have become a common method for forecasting glucose values using data from CGMs. One method of forecasting glucose values is a time-delay feedforward (FF) NN, but a change in the CGM location on a participant can increase forecast error in a FF NN. METHODS: In response, we examined a NN with gated recurrent units (GRUs) as a method of reducing forecast error due to changes in sensor location. RESULTS: We observed that for 13 participants with type 2 diabetes wearing blinded CGMs on both arms for 12 weeks (FreeStyle Libre Pro-Abbott), GRU NNs did not produce significantly different errors in glucose prediction due to sensor location changes (P < .05). CONCLUSION: We observe that GRU NNs can mitigate error in glucose prediction due to differences in CGM location.

Design and proof-of-concept evaluation of a touchless connector system for preventing peritoneal dialysis-associated peritonitis.

Introduction: In this paper, we describe the design of a touchless peritoneal dialysis connector system and how we evaluated its potential for preventing peritoneal dialysis-associated peritonitis, in comparison to the standard of care. The unique feature of this system is an enclosure within which patients can connect and disconnect for therapy, protecting their peritoneal catheters from touch or aerosols. Methods: We simulated a worst-case contamination scenario by spraying 40mL of a standardized inoculum [ 1×107 colony-forming units (CFU) per milliliter] of test organisms, Staphylococcus epidermidis ATCC1228 and Pseudomonas aeruginosa ATCC39327, while test participants made mock connections for therapy. We then compared the incidence of fluid path contamination by test organisms in the touchless connector system and the standard of care. 4 participants were recruited to perform a total of 56 tests, divided in a 1:1 ratio between both systems. Peritoneal dialysis fluid sample from each test was collected and maintained at body temperature (37° C) for 16 hours before being plated on Luria Bertani agar, Mannitol Salts Agar and Pseudomonas isolation agar for enumeration. Results: No contamination was observed in test samples from the touchless connector system, compared to 65%, 75% and 70% incidence contamination for the standard of care on Luria Bertani agar, Mannitol Salts Agar and Pseudomonas isolation agar respectively. Conclusion: Results show that the touchless connector system can prevent fluid path contamination even in heavy bacterial exposures and may help reduce peritoneal dialysis-associated peritonitis risks from inadvertent contamination with further development.

Examining Sensor Agreement in Neural Network Blood Glucose Prediction.

Successful measurements of interstitial glucose are a key component in providing effective care for patients with diabetes. Recently, there has been significant interest in using neural networks to forecast future glucose values from interstitial measurements collected by continuous glucose monitors (CGMs). While prediction accuracy continues to improve, in this work we investigated the effect of physiological sensor location on neural network blood glucose forecasting. We used clinical data from patients with Type 2 Diabetes who wore blinded FreeStyle Libre Pro CGMs (Abbott) on both their right and left arms continuously for 12 weeks. We trained patient-specific prediction algorithms to test the effect of sensor location on neural network forecasting (N = 13, Female = 6, Male = 7). In 10 of our 13 patients, we found at least one significant (P < .05) increase in forecasting error in algorithms which were tested with data taken from a different location than data which was used for training. These reported results were independent from other noticeable physiological differences between subjects (eg, height, age, weight, blood pressure) and independent from overall variance in the data. From these results we observe that CGM location can play a consequential role in neural network glucose prediction.

Computer-Generated Three-Dimensional Airway Models as a Decision-Support Tool for Preoperative Evaluation and Procedure-Planning in Pediatric Anesthesiology.

Technology improvements have rapidly advanced medicine over the last few decades. New approaches are constantly being developed and utilized. Anesthesiology strongly relies on technology for resuscitation, life-support, monitoring, safety, clinical care, and education. This manuscript describes a reverse engineering process to confirm the fit of a medical device in a pediatric patient. The method uses virtual reality and three-dimensional printing technologies to evaluate the feasibility of a complex procedure requiring one-lung isolation and one-lung ventilation. Based on the results of the device fit analysis, the anesthesiology team confidently proceeded with the operation. The approach used and described serves as an example of the advantages available when coupling new technologies to visualize patient anatomy during the procedural planning process.

Low cost 3D printed clamps for external fixator for developing countries: a biomechanical study.

BACKGROUND: External fixation is a mainstream limb reconstruction technique, most often used after a traumatic injury. Due to the high rates of trauma in developing countries, external fixation devices are often utilized for immediate fracture stabilization and soft tissue repair. Proper external fixation treatment too often still fails to be adopted in these regions due to the high cost and trauma complexity. A novel, inexpensive, unilateral fixator was constructed using 3D printed clamps and other readily available supporting components. ASTM standard F1541 tests were used to assess the biomechanical properties of this novel external fixator. METHODS: Applicable sections of ASTM standard F1541 were used to determine the biomechanical properties of the novel external fixator. 3D printed clamps modeled using SolidWorks and printed with chopped carbon fibers using a fuse deposition modeling (FDM) based 3D printer by Markforged (Boston, MA) were used. This study included 3 different testing configurations: axial compression, anterior-posterior (AP) bending, and medial-lateral (ML) bending. Using the novel unilateral fixator with 3D printed clamps previously sterilized by autoclave, an input load was applied at a rate of 20 N/s, starting at 0 N via a hydraulic MTS tester Model 359. Force and deformation data were collected at a sampling rate of 30 Hz. There was a load limit of 750 N, or until there was a maximum vertical deformation of 6 mm. Also, 4 key dimensions of the 3D printed clamps were measured pre and post autoclave: diameter, width, height and length. RESULTS: The novel external fixator had axial compression, AP and ML bending rigidities of 246.12 N/mm (σ = 8.87 N/mm), 35.98 N/mm (σ = 2.11 N/mm) and 39.60 N/mm (σ =2.60 N/mm), respectively. The 3D printed clamps shrunk unproportionally due to the autoclaving process, with the diameter, width, height and length dimensions shrinking by 2.6%, 0.2%, 1.7% and 0.3%, respectively. CONCLUSION: Overall, the biomechanical properties of the novel fixator with 3D printed clamps assessed in this study were comparable to external fixators that are currently being used in clinical settings. While the biomechanics were comparable, the low cost and readily available components of this design meets the need for low cost external fixators in developing countries that current clinical options could not satisfy. However, further verification and validation routines to determine efficacy and safety must be conducted before this novel fixator can be clinically deployed. Also, the material composition allowed for the clamps to maintain the appropriate shape with minimal dimensional shrinkage that can be accounted for in clamp design.

Diagnostics as the Key to Advances in Global Health: Proposed Methods for Making Reliable Diagnostics Widely Available.

This paper proposes a structure and method for the development of an AI diagnostic system as a highly leveraged step toward improvements in delivery of healthcare in underserved regions. First, the paper provides a high-level, general review of the current efforts to provide healthcare services in underserved areas and the many efforts being made to impact health outcomes by various international, governmental, and NGO entities. We also very briefly review university programs and research institutions that have specific technical and institutional assets with significant potential to carry out research or to partially implement such a plan. Our review uses weighted values in a decision-system that takes in a variety of assets we consider fundamental to successful engagement in delivery of new, innovative, technology-enabled healthcare systems for under-resourced settings. We then review nine factors that hinder the advancement in healthcare in under-resourced settings, some of which are well described in current literature and some that may bring new perspectives. The paper then attempts to review how a proposed system can manage to operate successfully within the context of the nine named hindrance factors. The primary focus of the paper is in the description of a system which can increase the availability of diagnostics through technology-enabled systems. Such a system would impact the outcomes of persons in underserved regions. The paper then describes why making diagnostics available is a critical priority among efforts for improvements in global health.

The association between janitor physical workload, mental workload, and stress: The SWEEP study.

BACKGROUND: Approximately 2.38 million janitors are employed in the U.S. While high physical workload may explain a lost-work days rate 2.7 times greater than other occupations, little is known about the association between janitors' physical workload, mental workload, and stress. OBJECTIVE: The objective of this study was to assess the associations between physical (ergonomic) and mental workload exposures and stress outcomes among janitors. METHODS: Questionnaire data, focused on ergonomic workload, mental workload and stress, were collected from Minnesota janitors for a one-year period. Physical workload was assessed with Borg Scales and Rapid Entire Body Assessments (REBA). Mental workload assessment utilized the NASA Task Load Index (TLX). Stress assessments utilized single-item ordinal stress scale (SISS) and Perceived Stress Scale-4 (PSS-4) measures. Descriptive and multivariable analyses, including bias adjustment, were conducted. RESULTS: Odds ratios (OR) and 95% confidence intervals (CI) for ergonomic workload (task frequency) effects on SISS were: REBA (1.18 OR, 1.02-1.37 CI); Borg (1.25 OR, 1.00-1.56 CI); combined REBA and Borg (1.10 OR, 1.01-1.20 CI). Mental workload was associated with higher PSS-4 levels (0.15 Mean Difference, 0.08-0.22 CI) and a 3% increased risk for each one-unit increase in the SISS scale (1.03 OR, 1.02-1.05 CI). CONCLUSIONS: This research demonstrated a moderate effect of physical and mental workloads on stress among janitors.

Cardiac patient-specific three-dimensional models as surgical planning tools.

BACKGROUND: Three-dimensional printing is an additive manufacturing method that builds objects from digitally generated computational models. Core technologies behind three-dimensional printing are evolving rapidly with major advances in materials, resolution, and speed that enable greater realism and higher accuracy. These improvements have led to novel applications of these processes in the medical field. METHODS: The process of going from a medical image data set (computed tomography, magnetic resonance imaging, ultrasound) to a physical three-dimensional print includes several steps that are described. Medical images originate from Digital Imaging and Communications in Medicine files or data sets, the current standard for storing and transmitting medical images. Via Digital Imaging and Communications in Medicine manipulation software packages, a segmentation process, and manual intervention by an expert user, three-dimensional digital and printed models can be constructed in great detail. RESULTS: Cardiovascular medicine is one of the fastest growing applications for medical three-dimensional printing. The technology is more frequently being used for patient and clinician education, preprocedural planning, and medical device design and prototyping. We report on three case studies, describing how our three-dimensional printing has contributed to the care of cardiac patients at the University of Minnesota. CONCLUSION: Medical applications of computational three-dimensional modeling and printing are already extensive and growing rapidly and are routinely used for visualizing complex anatomies from patient imaging files to plan surgeries and create surgical simulators. Studies are needed to determine whether three-dimensional printed models are cost effective and can consistently improve clinical outcomes before they become part of routine clinical practice.

Use of virtual reality for pre-surgical planning in separation of conjoined twins: A case report.

We describe the use of virtual reality technology for surgical planning in the successful separation of thoracopagus conjoined twins. Three-dimensional models were created from computed tomography angiograms to simulate the patient's anatomy on a virtual stereoscopic display. Members of the surgical teams reviewed the anatomical models to localize an interatrial communication that allowed blood to flow between the two hearts. The surgical plan to close the 1-mm interatrial communication was significantly modified based on the pre-procedural spatial awareness of the anatomy presented in the virtual visualization. The virtual stereoscopic display was critical for the surgical team to successfully separate the twins and provides a useful case study for the use of virtual reality technology in surgical planning. Both twins survived the operation and were subsequently discharged from the hospital.

Janitor ergonomics and injuries in the safe workload ergonomic exposure project (SWEEP) study.

INTRODUCTION: A Minnesota union identified to researchers at the University of Minnesota a concern relevant to a possible relation between their daily workload and outcome of occupational injuries among a population of janitors. OBJECTIVE: To assess if the ergonomic workload is related to injuries among janitors. METHODS: Following an initial group discussion among janitors, which identified common and hazardous tasks potentially leading to occupational injuries, a questionnaire was developed, pre-tested, and distributed to the janitors. Questions addressed various exposures, including workload, and comprehensive information regarding injury occurrence over two six-month sequential periods (May 2016-October 2016, November 2016-April 2017). Quantitative ergonomic analyses were performed on a sub-group of janitors (n = 30); these included data collection to identify Borg Perceived Exertion (Borg) and Rapid Entire Body Assessment (REBA) scores. Descriptive, multivariable with bias adjustment analyses were conducted on the resulting data. RESULTS: Eight tasks were found to be common for janitors. All average REBA scores for the tasks were identified in the high-risk category. The task of repeatedly emptying small trash cans (<25lb) was significantly related to injuries. Average Borg scores fell between the very light perceived exertion and somewhat difficult perceived exertion categories. Multivariable regression analyses indicated that age-sex-standardized ergonomic workload, measured by task frequencies and REBA or Borg scores, was positively related to injury occurrence. CONCLUSIONS: Standardized ergonomic workload was positively related to injury occurrence. This information serves as a basis for further research and potential intervention efforts.

Novel design and development of a 3D-printed conformal superficial brachytherapy device for the treatment of non-melanoma skin cancer and keloids.

BACKGROUND: Skin tumors are the most predominant form of cancer in the United States. Radiation therapy, particularly high dose-rate (HDR) brachytherapy, provides an effective form of cancer control when surgery is not possible or when surgical margins are incomplete. The treatment of superficial skin cancers on irregular surfaces, such as the nose, lips or ears, present challenges for treatment. To address this issue, we designed and constructed a novel conformal superficial brachytherapy (CSBT) device prototype to improve patient-specific treatment for complex sites. The device is mounted on an automated remote after-loader, providing limited radiation exposure to operating personnel, is inexpensive to construct, and offers a unique method of conformal surface radiation therapy. RESULTS: A prototype of the CSBT device was successfully manufactured. A computed tomography (CT) scan of a Rando phantom was used to plan the target treatment area. The CSBT device has a hexagonal lattice array of retractable rods with radioactive seeds placed at the tip of each rod. A 3D-printed conformal shape insert with a hexagonal array of cylindrical projections of varying length is driven into the rods by a single linear actuator. The rods are displaced to conform to the patient's skin. This elegant device design permits the delivery of radiation to complex targets using readily available beta-emitting radionuclides, such as Yttrium-90 (Y-90) or Strontium-90 (Sr-90). CONCLUSION: A working prototype of a novel CSBT device was built using 3D-printing technology that provides a safe and economically attractive means of improving radiation delivery to complex treatment sites.

Bento Box: An Interactive and Zoomable Small Multiples Technique for Visualizing 4D Simulation Ensembles in Virtual Reality.

We present Bento Box, a virtual reality data visualization technique and bimanual 3D user interface for exploratory analysis of 4D data ensembles. Bento Box helps scientists and engineers make detailed comparative judgments about multiple time-varying data instances that make up a data ensemble (e.g., a group of 10 parameterized simulation runs). The approach is to present an organized set of complementary volume visualizations juxtaposed in a grid arrangement, where each column visualizes a single data instance and each row provides a new view of the volume from a different perspective and/or scale. A novel bimanual interface enables users to select a sub-volume of interest to create a new row on-the-fly, scrub through time, and quickly navigate through the resulting virtual "bento box." The technique is evaluated through a real-world case study, supporting a team of medical device engineers and computational scientists using in-silico testing (supercomputer simulations) to redesign cardiac leads. The engineers confirmed hypotheses and developed new insights using a Bento Box visualization. An evaluation of the technical performance demonstrates that the proposed combination of data sampling strategies and clipped volume rendering is successful in displaying a juxtaposed visualization of fluid-structure-interaction simulation data (39 GB of raw data) at interactive VR frame rates.

The Wall Apposition Evaluation for a Mechanical Embolus Retrieval Device.

A computational evaluation approach to the wall apposition of a cerebral mechanical emboli retrieval device (MERD) is presented. The typical enclosed multilattice structure, manufactured from the thin-walled Nitinol tube, consists of repeated "V"-shaped unit cells. During interventional thrombectomy, the MERD system is delivered inside an artery stenosis segment to capture emboli and restore cerebral blood flow. The wall apposition, which deteriorates during embolus capture, occurs during system migration along the tortuous intracranial vessel. The commercial finite element analysis (FEA) solver ABAQUS 6.10 Standard and user subroutine (UMAT/Nitinol) are utilized to study the ability to remain in close contact with the curved vessel wall during migration. In this numerical analysis, the influence of the contacting interference loadings on structure deformation and strain field distribution is obtained and analyzed. The results indicate that the middle segment of the MERD seriously contracts or collapses inside the curved vessel. In addition, the peak strain is in the apex flow-prone region and maintains at the safe range.

Optimizing Design With Extensive Simulation Data: A Case Study of Designing a Vacuum-Assisted Biopsy Tool.

Design by Dragging (DBD) [1] is a virtual design tool, which displays three-dimensional (3D) visualizations of many simulation results obtained by sampling a large design space and ties this visual display together with a new user interface. The design space is explored through mouse-based interactions performed directly on top of the 3D data visualizations. Our previous study [1] introduced the realization of DBD with a simplistic example of biopsy needle design under a static bending force. This paper considers a realistic problem of designing a vacuum-assisted biopsy (VAB) needle that brings in more technical challenges to include dynamic tissue reaction forces, nonlinear tissue deformation, and progressive tissue damage in an integrated visualization with design suggestions. The emphasis is placed on the inverse design strategy in DBD, which involves clicking directly on a stress (or other output field parameter) contour and dragging it to a new (usually preferable) position on the contour. Subsequently, the software computes the best fit for the design variables for generating a new output stress field based on the user input. Three cases demonstrated how the inverse design can assist users in intuitively and interactively approaching desired design solutions. This paper illustrates how virtual prototyping may be used to replace (or reduce reliance on) purely experimental trial-and-error methods for achieving optimal designs.

Beneficial Effects of Spatial Remapping for Reading With Simulated Central Field Loss.

Purpose: People with central field loss (CFL) lose information in the scotomatous region. Remapping is a method to modify images to present the missing information outside the scotoma. This study tested the hypothesis that remapping improves reading performance for subjects with simulated CFL. Methods: Circular central scotomas, with diameters ranging from 4° to 16°, were simulated in normally sighted subjects using an eye tracker on either a head-mounted display (HMD) (experiments 1, 2) or a traditional monitor (experiment 3). In the three experiments, reading speed was measured for groups of 7, 11, and 13 subjects with and without remapping of text. Results: Remapping increased reading speed in all three experiments. On the traditional monitor, it increased reading speed by 34% (8°), 38% (12°), and 35% (16°). In the two HMD experiments, remapping increased reading speed only for the largest scotoma size, possibly due to latency of updating of the simulated scotoma. Conclusions: Remapping significantly increased reading speed in simulated CFL subjects. Additional testing should examine the efficacy of remapping for reading and other visual tasks for patients with advanced CFL.