KeyLoop retractor for global gasless laparoscopy: evaluation of safety and feasibility in a porcine model

BACKGROUND

Many surgeons in low- and middle-income countries have described performing surgery using gasless (lift) laparoscopy due to inaccessibility of carbon dioxide and reliable electricity, but the safety and feasibility of the technique has not been well documented. We describe preclinical testing of the in vivo safety and utility of KeyLoop, a laparoscopic retractor system to enable gasless laparoscopy.

METHODS

Experienced laparoscopic surgeons completed a series of four laparoscopic tasks in a porcine model: laparoscopic exposure, small bowel resection, intracorporeal suturing with knot tying, and cholecystectomy. For each participating surgeon, the four tasks were completed in a practice animal using KeyLoop. Surgeons then completed these tasks using standard-of-care (SOC) gas laparoscopy and KeyLoop in block randomized order to minimize learning curve effect. Vital signs, task completion time, blood loss and surgical complications were compared between SOC and KeyLoop using paired nonparametric tests. Surgeons completed a survey on use of KeyLoop compared to gas laparoscopy. Abdominal wall tissue was evaluated for injury by a blinded pathologist.

RESULTS

Five surgeons performed 60 tasks in 15 pigs. There were no significant differences in times to complete the tasks between KeyLoop and SOC. For all tasks, there was a learning curve with task completion times related to learning the porcine model. There were no significant differences in blood loss, vital signs or surgical complications between KeyLoop and SOC. Eleven surgeons from the United States and Singapore felt that KeyLoop could be used to safely perform several common surgical procedures. No abdominal wall tissue injury was observed for either KeyLoop or SOC.

CONCLUSIONS

Procedure times, blood loss, abdominal wall tissue injury and surgical complications were similar between KeyLoop and SOC gas laparoscopy for basic surgical procedures. This data supports KeyLoop as a useful tool to increase access to laparoscopy in low- and middle-income countries.

Simulation device for shoulder reductions: overview of prototyping, testing, and design instructions

BACKGROUND

Shoulder dislocations are common occurrences, yet there are few simulation devices to train medical personnel on how to reduce these dislocations. Reductions require a familiarity with the shoulder and a nuanced motion against strong muscle tension. The goal of this work is to describe the design of an easily replicated, low-cost simulator for training shoulder reductions.

MATERIALS AND METHODS

An iterative, stepwise engineering design process was used to design and implement ReducTrain. A needs analysis with clinical experts led to the selection of the traction-countertraction and external rotation methods as educationally relevant techniques to include. A set of design requirements and acceptance criteria was established that considered durability, assembly time, and cost. An iterative prototyping development process was used to meet the acceptance criteria. Testing protocols for each design requirement are also presented. Step-by-step instructions are provided to allow the replication of ReducTrain from easily sourced materials, including plywood, resistance bands, dowels, and various fasteners, as well as a 3D-printed shoulder model, whose printable file is included at a link in the Additional file 1: Appendix.

RESULTS

A description of the final model is given. The total cost for all materials for one ReducTrain model is under US $200, and it takes about 3 h and 20 min to assemble. Based on repetitive testing, the device should not see any noticeable changes in durability after 1000 uses but may exhibit some changes in resistance band strength after 2000 uses.

DISCUSSION

The ReducTrain device fills a gap in emergency medicine and orthopedic simulation. Its wide variety of uses points to its utility in several instructional formats. With the rise of makerspaces and public workshops, the construction of the device can be easily completed. While the device has some limitations, its robust design allows for simple upkeep and a customizable training experience.

CONCLUSION

A simplified anatomical design allows for the ReducTrain model to serve as a viable training device for shoulder reductions.

Low Cost Gastroschisis Silo for Sub-Saharan Africa: Testing in a Porcine Model

BACKGROUND

Gastroschisis mortality in sub-Saharan Africa (SSA) remains high at 59-100%. Silo inaccessibility contributes to this disparity. Standard of care (SOC) silos cost $240, while median monthly incomes in SSA are < $200. Our multidisciplinary American and Ugandan team designed and bench-tested a low-cost (LC) silo that costs < $2 and is constructed from locally available materials. Here we describe in vivo LC silo testing.

METHODS

A piglet gastroschisis model was achieved by eviscerating intestines through a midline incision. Eight piglets were randomized to LC or SOC silos. Bowel was placed into the LC or SOC silo, maintained for 1-h, and reduced. Procedure times for placement, intestinal reduction, and silo removal were recorded. Tissue injury of the abdominal wall and intestine was assessed. Bacterial and fungal growth on silos was also compared.

RESULTS

There were no gross injuries to abdominal wall or intestine in either group or difference in minor bleeding. Times for silo application, bowel reduction, and silo removal between groups were not statistically or clinically different, indicating similar ease of use. Microbiologic analysis revealed growth on all samples, but density was below the standard peritoneal inoculum of 10⁵ CFU/g for both silos. There was no significant difference in bacterial or fungal growth between LC and SOC silos.

CONCLUSION

LC silos designed for manufacturing and clinical use in SSA demonstrated similar ease of use, absence of tissue injury, and acceptable microbiology profile, similar to SOC silos. The findings will allow our team to proceed with a pilot study in Uganda.

Design and Development of a Novel System for Remote Control of Stationary Oxygen Concentrator Flow Rate

Purpose

Long-term oxygen therapy involves utilizing stationary oxygen concentrators to allow patients with respiratory illnesses to attain sufficient blood oxygenation via supplemental oxygen. Disadvantages of these devices include their lack of remote adjustability and domiciliary accessibility. To adjust oxygen flow, patients typically walk across their homes - a physically taxing activity - to manually rotate the knob of the concentrator flowmeter. The purpose of this investigation was to develop a control system device that allows patients to remotely adjust the oxygen flow rates on their stationary oxygen concentrator.

Methods

The engineering design process was used to develop the novel FLO2 device. The two-part system is composed of 1) a smartphone application and 2) an adjustable concentrator attachment unit that mechanically interfaces with the stationary oxygen concentrator flowmeter.

Results

Product testing indicates that users successfully communicated to the concentrator attachment from a maximum distance of 41m in an open field, suggesting usability from anywhere inside a standard home. The calibration algorithm adjusted oxygen flow rates with an accuracy of ±0.019 LPM and a precision of ±0.042 LPM.

Conclusion

Initial design testing suggests the device as a reliable and accurate method of wirelessly adjusting oxygen flow on a stationary oxygen concentrator, but further testing should be performed on different stationary oxygen concentrator models.

Atypical Presentation in Sclerosing Epithelioid Fibrosarcoma: A Case Report

Introduction/Objective

Sclerosing Epithelioid Fibrosarcoma (SEF) is a rare sarcoma with characteristic EWSR1::CREB3L1 fusion and MUC4 positivity by immunohistochemistry (IHC). SEF most often presents as a primary soft tissue tumor in the lower extremities. Histologically, SEF is characterized by cords, nests or sheets of monotonous, epithelioid tumor cells in a dense collagenous background. We report a case of SEF in an atypical location with unique histological and atypical cytogenetic findings.

Methods/Case Report

A 13-year-old male presented with left leg and back pain. A CT scan demonstrated a 7.3 x 5.7 x 6.8 cm left hemiabdomen mesenteric mass with metastatic nodules in the pancreas, liver, L1 vertebrae and sacrum. Sacral biopsy demonstrated infiltrative and discohesive nests of small to medium round cells with scant eosinophilic to clear cytoplasm but without conspicuous tumor stroma. An extensive IHC panel was positive only for CD99. Fluorescence in-situ hybridization (FISH) demonstrated an unusual finding with a variant pattern. FISH revealed an EWSR1 rearrangement with an unidentified partner. The tumor karyotype was normal in the dividing cells utilized for chromosome analysis, suggesting the rearrangement was enriched in the non-dividing cell population. Next- generation sequencing (NGS) revealed a EWSR1::CREB3L1 fusion that was confirmed by FISH, and MUC4 was positive by IHC, further supporting classification as SEF.

Results (if a Case Study enter NA)

NA

Conclusion

Due to the atypical presentation and histologic appearance of this rare sarcoma, integration of IHC, FISH, and NGS were required to fully characterize the lesion.

Learning Environments and Evidence-Based Practices in Bioengineering and Biomedical Engineering

This paper provides a synopsis of discussions related to the Learning Environments track of the Fourth BME Education Summit held at Case Western Reserve University in Cleveland, Ohio in May 2019. This summit was organized by the Council of Chairs of Bioengineering and Biomedical Engineering, and participants included over 300 faculty members from 100+ accredited undergraduate programs. The Learning Environments track had six interactive workshops that provided facilitated discussion and provide recommendations in the areas of: (1) Authentic project/problem identification in clinical, industrial, and global settings, (2) Experiential problem/project-based learning within courses, (3) Experiential learning in co-curricular learning settings, (4) Team-based learning, (5) Teaching to reach a diverse classroom, and (6) Innovative platforms and pedagogy. A summary of the findings, best practices and recommendations from each of the workshops is provided under separate headings below, and a list of resources is provided at the end of this paper.

Multidisciplinary Development of a Low-Cost Gastroschisis Silo for Use in Sub-Saharan Africa

BACKGROUND

Gastroschisis silos are often unavailable in sub-Saharan Africa (SSA), contributing to high mortality. We describe a collaboration between engineers and surgeons in the United States and Uganda to develop a silo from locally available materials.

METHODS

Design criteria included the following: < $5 cost, 5 ± 0.25 cm opening diameter, deformability of the opening construct, ≥ 500 mL volume, ≥ 30 N tensile strength, no statistical difference in the leakage rate between the low-cost silo and preformed silo, ease of manufacturing, and reusability. Pugh scoring matrices were used to assess designs. Materials considered included the following: urine collection bags, intravenous bags, or zipper storage bags for the silo and female condom rings or O-rings for the silo opening construct. Silos were assembled with clothing irons and sewn with thread. Colleagues in Uganda, Malawi, Tanzania, and Kenya investigated material cost and availability.

RESULTS

Urine collection bags and female condom rings were chosen as the most accessible materials. Silos were estimated to cost < $1 in SSA. Silos yielded a diameter of 5.01 ± 0.11 cm and a volume of 675 ± 7 mL. The iron + sewn seal, sewn seal, and ironed seal on the silos yielded tensile strengths of 31.1 ± 5.3 N, 30.1 ± 2.9 N, and 14.7 ± 2.4 N, respectively, compared with the seal of the current standard-of-care silo of 41.8 ± 6.1 N. The low-cost silos had comparable leakage rates along the opening and along the seal with the spring-loaded preformed silo. The silos were easily constructed by biomedical engineering students within 15 min. All silos were able to be sterilized by submersion.

CONCLUSIONS

A low-cost gastroschisis silo was constructed from materials locally available in SSA. Further in vivo and clinical studies are needed to determine if mortality can be improved with this design.

Maji: a new tool to prevent overhydration of children receiving intravenous fluid therapy in low-resource settings

We designed and evaluated the accuracy and usability of a device to regulate the volume of fluid dispensed during intravenous drip therapy. The mechanical system was developed in response to a pressing need articulated by clinicians in pediatric wards throughout sub-Saharan Africa, who require a tool to prevent overhydration in children receiving intravenous fluid in settings that lack burettes or electronic infusion pumps. The device is compatible with most intravenous bags and limits the volume dispensed to a preset amount that can be adjusted in 50 mL increments. Laboratory accuracy over a range of clinically-relevant flow rates, initial bag volumes, and target volumes was within 12.0 mL of the target volume. The ease of use is "excellent," with a mean system usability score of 84.4 out of 100. Use of the device limits the volume of fluid dispensed during intravenous therapy and could potentially reduce the morbidity and mortality associated with overhydration in children receiving intravenous therapy.

A laboratory batch reactor test for assessing nonspeciated volatile organic compound biodegradation in activated sludge

The relative rates of biodegradation and stripping and volatilization of nonspeciated volatile organic compounds (VOCs) in wastewater treated with aerobic activated-sludge processes can be quantified using a newly developed procedure. This method was adapted from the original aerated draft tube reactor test that was developed to measure biodegradation rate constants for specific volatile pollutants of interest. The original batch test has been modified to include solid-phase microextraction (SPME) fibers for sampling in the gas phase. The experimental procedure using SPME fibers does not require specific identification and quantitation of individual pollutants and can be used to evaluate wastewater with multiple VOCs. To illustrate use of this procedure, laboratory experiments were conducted using biomass and wastewater or effluent from three activated-sludge treatment systems. Each experiment consisted of two trials: a stripping-only trial without biomass and a stripping plus biodegradation trial using biomass from the activated-sludge unit of interest. Data from the two trials were used to quantify the rates of biodegradation by difference. The activated-sludge systems tested were a laboratory diffused-air reactor treating refinery wastewater, a full-scale surface aerated reactor treating a petrochemical wastewater, and a full-scale diffused-air reactor treating a variety of industrial effluents. The biodegradation rate constant data from each laboratory batch experiment were used in model calculations to quantify the fraction emitted (fe) and the fraction biodegraded (fbio) for each system. The fe values ranged from a maximum of 0.01 to a maximum of 0.32, whereas fbio values ranged from a minimum of 0.40 to a minimum 0.95. Two of these systems had been previously tested using a more complicated experimental approach, and the current results were in good agreement with previous results. These results indicate that biodegradation rate constant data from this laboratory method can be successfully used to predict the fate of VOCs in field-scale treatment units, and thus could potentially be used for demonstration of compliance with wastewater VOC emission regulations.

Nonoperative management of dens fracture nonunion in elderly patients without myelopathy

STUDY DESIGN

A retrospective review of elderly patients treated without surgery for chronic mobile nonunions of the odontoid process. Patients were observed on an annual basis with clinical examinations and flexion/extensions plain film radiographs.

OBJECTIVES

To evaluate the clinical and radiographic results of elderly patients without myelopathy treated without surgery for dens fracture nonunion.

SUMMARY OF BACKGROUND DATA

Because of the risk of progressive myelopathy or sudden neurologic injury, many surgeons recommend operative stabilization for patients with mobile dens nonunions who are able to withstand an operation. There is, however, a lack of information about the radiographic and neurologic progression of dens nonunions. Although a less aggressive surgical approach has been recommended by some authors for elderly or medically compromised patients with acute fractures, long-term follow-up evaluation of patients with resulting nonunions has not been reported.

METHODS

A series of elderly patients with chronic, unstable, dens nonunions without myelopathy were treated with a nonoperative treatment protocol. Patients were informed of the nature of their lesion, including the risk of acute or chronic spinal cord injury and the options for operative treatment. Patients were evaluated yearly for clinical and radiographic progression. No intervention to slow progression of atlantoaxial instability was undertaken.

RESULTS

None of the patients developed myelopathic symptoms during the follow-up period, and no patient experienced more than a 1 mm radiographic increase in atlantoaxial excursion. None of the reported patients had less than 14 mm available for the spinal cord in either flexion or extension at the start of clinical monitoring.

CONCLUSIONS

Although further follow-up evaluation is needed, the authors believe on the basis of this review that this treatment protocol may be considered for patients who are poor candidates for surgical fusion.

Stulberg classification system for evaluation of Legg-Calvé-Perthes disease: intra-rater and inter-rater reliability

BACKGROUND

Researchers and clinicians commonly use the classification system of Stulberg et al. as a basis for treatment decisions during the active phase of Legg-Calvé-Perthes disease because of its putative utility as a predictor of long-term outcome. It is generally assumed that this system has an acceptable degree of reliability. This assumption, however, is not convincingly supported by the literature.

METHODS

The purpose of the present study was to assess the inter-rater and intra-rater reliability of the classification system of Stulberg et al. with use of a pre-test, post-test design. During the pre-test phase, nine raters independently used the system to evaluate the radiographs of skeletally mature patients who had been managed for Legg-Calvé-Perthes disease. The intervention between the pre-test and post-test phases consisted of a consensus-building session during which all raters jointly arrived at standardized definitions of the various joint structures that are assessed with use of the classification system. The effect of these definitions on reliability then was assessed by reevaluating the radiographs during the post-test phase.

RESULTS

The pre-test intra-rater reliability coefficients ranged from 0.709 to 0.915, and the post-test coefficients ranged from 0.568 to 0.874. The pre-test inter-rater reliability coefficients ranged from 0.603 to 0.732, and the post-test coefficients ranged from 0.648 to 0.744. Contributing to the variance was a lack of agreement concerning the assessment of joint structures and the way in which the raters translated these evaluations into a classification according to the system of Stulberg et al.

CONCLUSIONS

Although intra-rater reliability was marginally acceptable, the degree of variability between the classifications assigned by different raters even after the intervention - calls into question the reliability of the system of Stulberg et al.; consequently, the validity of any treatment decisions, outcome evaluations, or epidemiological studies based on this system is also in question.

Adhesion mediated by bonds in series

Cell adhesion in physiological situations and biotechnological applications is often mediated through serial protein/protein linkages. The adhesion strength of cell/substrate contacts through receptor/ligand bonds in series is explored with a simple mathematical model and quantified with an experimental adhesion assay. A deterministic, mass-action model is developed to describe the attachment and detachment of cell/substrate contacts through single and serial bonds. The experimental system is comprised of protein-coated beads, soluble antibody linkers, and an antibody-coated glass surface. Using the Radial-Flow Detachment Assay, the adhesion strengths of bead/substrate contacts through single and serial linkages are measured. Taken together, this work shows that the specific adhesion strength of the cell/substrate contacts comprised of two receptor/ligand bonds in series is less than the specific adhesion strength of the cell/substrate contacts comprised of either of the bonds separately. In addition, the force to rupture contacts comprised of bonds in series varies with the concentration of the solution linker. The model predicts that the locus of linkage fracture location has only a mild dependence on the ratio of relative bond affinities.

Use of knee braces in sport. Current recommendations

This article provides a review of the progress that has been made on the biomechanical, functional performance and epidemiological investigations into the effectiveness of prophylactic knee braces (PKBs) since the position statement against their use was issued in 1987 by the American Academy of Orthopaedics and a review of this subject was last published in Sports Medicine in 1989 by Montgomery and Korziris. The evolution of the salient design features of three surrogate knee models are reviewed along with the results of PKB effectiveness and safety factor testing. While still too limited in scope to be totally realistic, major advances have been made in the sophistication of the present biomechanics laboratory testing conditions. The on-the-field functional performance effects of wearing a knee brace are not always manifest in all individuals. The efficacy of PKBs remains in question but recent studies have taught us enough to put their use into perspective. While they may play some role, PKBs probably represent the least important factor in influencing the likelihood that a medial collateral ligament (MCL) sprain will occur. On the other hand, there is no evidence that such braces put added valgus pressure on some knees, or that wearing a brace is associated with an increased frequency or severity of knee or ankle injury. All else being equal, from the biomechanical studies, we know that whilst some braces are better than others, currently available PKBs can provide 20 to 30% greater resistance to a lateral blow, with the possibility that the anterior cruciate ligament (ACL) is given even greater protection than the MCL. This appears to be true when the lateral blow is of sufficient magnitude to cause significant medial joint line opening, but is not as great at the very lowest levels of impact. Regardless of the material they are made of, the most effective PKBs are those sufficiently stiff to prevent an external blow at the joint line from causing brace hinge contact with the knee tissues. Based on the superior results of the custom-fit functional braces, the most important future design feature appears to be the sizing and fitting of the thigh and tibial cuffs. On the negative side, the presence of a brace may slow an athlete's straight-ahead sprint speed and cause early fatigue to its wearer. This effect appears to vary from one brace to another according to its weight, design features, and pressure from the leg and thigh straps. However, it appears that knee braces do have the potential to restrict performance of the athlete for high-speed running but the effect is related to several factors. The weight of the brace resultant friction of the hinges, completeness of fit, and tightness of straps appear to be important. The most measurable effects include: increased muscular relaxation pressures; increased energy expenditure; and a related increase in blood lactate levels, maximal torque output, oxygen consumption and heart rate. On the other hand, experienced brace wearers and larger, stronger individuals displayed fewer, or no effects of donning a brace. Improvements in the protectiveness of the PKB are likely to accompany improvements in the ability to contour the braces to fit each individual's leg in the equipment room without the added expense of the cast-moulding process. Further improvement may be realised by friction-free polycentric joints, as well as an attachment system that minimises thigh and calf soft tissue compression perhaps by incorporating the braces into the trousers of the uniform to provide suspension from the waist.

Heterogeneity and probabilistic binding contributions to receptor-mediated cell detachment kinetics

Biospecific cell adhesion is mediated by receptor-ligand bonds. Early theoretical work presented a deterministic analysis of receptor-mediated cell attachment and detachment for a homogeneous cell population. However, initial comparison of a deterministic framework to experimental detachment profiles of model "cells" (antibody-coated latex beads) did not show qualitative or quantitative agreement (Cozens-Roberts, C., D.A. Lauffenburger, and J.A. Quinn. 1990. Biophys. J. 58:857-872). Hence, we determine the contributions of population heterogeneity and probabilistic binding to the detachment behavior of this experimental system which was designed to minimize experimental and theoretical complications. This work also corrects an error in the numerical solution of the probabilistic model of receptor-mediated cell attachment and detachment developed previously (Cozens-Roberts, C., D.A. Lauffenburger, and J.A. Quinn. 1990. Biophys J. 58:841-856). Measurement of the population distribution of the number of receptors per bead has enabled us to explicitly consider the effect of receptor number heterogeneity within the cell-surface contact area. A deterministic framework that incorporates receptor number heterogeneity qualitatively and quantitatively accounts in large part for the model cell detachment data. Using measured and estimated parameter values for the model cell system, we estimate that about 90% of the observed kinetic detachment behavior originates from heterogeneity effects, while about 10% is due to probabilistic binding effects. In general, these relative contributions may differ for other systems.