Enhancing Mimetic Three-Dimensional Modeling and Printing for Presurgical Planning Applications: Improved Soft Tissue Assesments, Analyses and Consolidation Strategies

Mimetic three-dimensional (3D) printing has been shown to enhance presurgical planning and improve patient outcomes. However, data inconsistencies and non-optimized soft tissue data management strategies have impaired efforts to characterize soft tissues and translate biophysical values to 3D printing media durometers and shore values. As a result, finished models are inconsistent and exhibit reduced mimetic qualities. Improving biophysical characterizations of soft tissues, analysis strategies, and consolidation infrastructures are important factors that will improve 3D modeling in a presurgical planning setting. In our ongoing associated studies, both physiologically viable and formalin fixed large mammalian tissues (including human) were assessed using uniaxial and biaxial testing strategies. Biophysical datasets were analyzed using a gated analysis strategy, tailored to data acquisition methods developed within the University of Minnesota Visible Heart® Labs (VHL). A SQL database was then constructed to consolidate analyzed data for future retrieval. This strong preliminary data is a foundation for further development and refinement of future studies. It is our long-term goal that these strategies be improved and adopted to enhance the mimetic qualities of 3D presurgical planning models.

The Self Actuated Tenim Hand: The Conversion of a Body-Driven Prosthesis to an Electromechanically Actuated Device

Users of body-driven prostheses often abandon their prostheses due to overexertion of their shoulders and a lack of features. The aim of this study was thus to design an electromechanical hand prosthesis that meets the functional and grasping requirements of prosthesis users. To this end, the Self-Actuated Tenim Hand (SATH), a functional electromechanically actuated prosthesis, was developed. The SATH, based on the novel body-driven Tenim Hand, incorporated design refinements that improved on its predecessor’s grasping capabilities. An electromechanical actuator and a wrist supination and pronation mechanism were integrated into the SATH thereby improving its functional capabilities. The Anthropomorphic Hand Assessment Protocol (AHAP) was used as a design validation tool to assess the functional capabilities of the SATH. The SATH performed satisfactorily in AHAP and achieved results that are comparable to scores obtained by a more advanced prosthesis.

The Many Technical Contributions of the Anatomage Table: Seeing Anatomy Differently

The Anatomage Table was originally marketed to medical schools as an anatomical training tool and to hospitals for preoperative planning. When Medtronic employees began to understand the power of the Anatomage Table for product development and data analysis, the uniqueness of how the table was utilized led to its many valuable contributions. The Anatomage Table has significantly reduced product development time with its ability to immediately render anatomical models in a way that allows the development team to evaluate outcomes and react with clear direction. It also reduces cognitive load for the users thereby expediting the interpretive process. The technology has become a tool to enhance research and training outcomes. This paper serves as an example to stimulate the use of this type of technology in similar applications. Hard data originating from controlled studies are not provided in this report due to the technology’s early use at Medtronic and the proprietary nature of the development processes on which the technology was used.

A Qualitative Comparison of the Covex Respirator with Face Shield Versus the N95 Respirator

In March 2020, the World Health Organization declared the novel coronavirus (COVID-19) outbreak a worldwide pandemic. The pandemic led to concerns of shortages regarding healthcare-related resources, including personal protective equipment (PPE), ventilators, and more. The uniquely designed COVEX respirator with face shield was engineered and manufactured by Augustine Surgical, Inc. to combat the PPE shortage. The novel COVEX mask is an “all-in-one” face shield and filter with a Viral Filtration Efficiency (VFE) greater than 99%. A standard respirator qualitative fit test was completed on the COVEX respirator as well as the current medical standard 3M N95 respirator. Fit test studies comparing the two masks yielded similar outcomes. The COVEX respirator had a qualitative fit test pass rate of 96.6% and the 3M N95 respirator had a pass rate of 93.3% (n=30). Participants also reported other variables comparing the comfort and fit of each mask, which is described further in the discussion. The COVEX respirator with face shield passed a standardized qualitative fit test at a rate similar to the current medical standard N95 respirator. Our results suggest that the COVEX mask may be a viable PPE option in the future.

Crisis Ventilator: A 3D Printed Option for Pressure Controlled Ventilation

During the Coronavirus-19, or COVID-19, pandemic there was an early shortage of available ventilators. Domestic production was limited by dependence on overseas sources of raw materials despite partnering with automotive manufacturers. Our group has developed a 3D printed alternative called the CRISIS ventilator. Its design is similar to existing resuscitator devices on the market and uses a modified Pressure-Control ventilation. Here we compare the performance of the device on a simulated ARDS lung and handling of different clinical scenarios included tension pneumothorax and bronchospasm.

Advanced Surface System for Central Venous Catheter Insertion Training

An advanced surface for Central Venous Catheterization (CVC) training and evaluation was designed using sensorization techniques, including the use of a hall effect sensor array to measure the insertion depth of a catheter. The sensor array was tested for accuracy in both static and dynamic scenarios, and was found to be sufficiently accurate; measuring position with an accuracy of ±1.1 mm on average. The highest deviations in measured positions were located at the extreme ends of the array where calculations rely on only a single sensor. The maximum deviation in measured position was found to be 3.5 mm. This low-cost system of catheter measurement has the potential to improve feedback and assessment of CVC training.

Evaluating the Potential Susceptibilities of Swine Bronchi to Colateral Damage from Applied Cryoablation

While thermal ablation to induce pulmonary vein isolation has proven to be successful in treating atrial fibrillation, the applied modalities create the possibilities for collateral damage to surrounding extracardiac structures. Bronchi are considered as one tissue susceptible to such collateral damage. Here, the relative impacts that focal cryoablation dosages have on bronchial tissues were investigated using an in vitro isolated tissue bath setup.

Neuromorphic Representation of Cardiac Data from the American Black Bear During Hibernation

Brain-inspired (neuromorphic) systems realize biological neural principles with Spiking Neural Networks (SNN) to provide high-performing, energy-efficient frameworks for robotics, artificial intelligence, and adaptive control. The Neural Engineering Framework (NEF) brings forth a theoretical framework approach for the representation of high-dimensional mathematical constructs with spiking neurons for the implementation of functional large-scale neural networks. Here, we explore the utilization of neuromorphic adaptive control for circadian modulated cardiac pacing by examining the neuromorphic representation of high-dimensional cardiac data. For this study, we have utilized a model from a data set acquired from an American black bear during hibernation. Black bears in Minnesota will hibernate for 4-6 months without eating and drinking while losing little muscle mass and remain relatively normothermic throughout the winter [10]. In the current study, we obtained EEG and ECG data from one black bear throughout the winter months in Grand Rapids, MN, represented with NEF. Our results demonstrated opposing requirements for neuromorphic representation. While using high synaptic time constants for obtained ECG data, provided desirable low pass filtering, representation of EEG data requires fast synapses and a high number of neurons. Although this is only an analysis of a small sample of the data available, these guidelines provided the robust pilot dataset to observe the SNN patterns during prolonged hibernation and pair this data with the cardiac responses and thus support research questions related to the autonomic tone during hibernation. This preliminary research will help further develop our neuromorphic adaptive controller to better adapt cardiac pacing to circadian rhythms. This unique dataset may pave the way toward deciphering the underlying neural mechanisms of hibernation, providing translational to humans.

Altered Vascular Contractilities Associated with the Applications of Irreversible Electroporation

As electroporation therapies become more widely used in the cardiac ablation space, there is a critical need to study the potential effects on surrounding tissues: collateral damage. Here we explored methods to study the effects applying electroporative energies on vascular smooth muscle: i.e., loss of vascular function when exposed to energies needed to induce irreversibly electroporative therapy to the myocardium.

Application of a Viscous Liquid as an Aerosol for Post-Operative Adhesion Prevention: First Engineering Steps Towards Nozzle Design

Postoperative adhesions are scar tissue that form between internal organs after surgery, leading to devastating life-long complications. Current adhesion barriers used clinically are solid sheets which can only be applied in open surgeries through large incisions. We have developed a material which can be applied as a liquid in minimally invasive surgeries which transitions into a solid thin film barrier upon contact with warm tissue. However, to be effective, it must be sprayed, and spraying a viscous liquid consistently is challenging. We proposed using a gas dispersant to facilitate aerosolization. In this study, we compared a commercially available nozzle without gas dispersant to a custom 3D printed nozzle with gas dispersant. For comparison, we measured both spray pattern and stiffness of the resulting gel. We found that when sprayed with gas dispersant, the spray pattern covered a larger area, and the resulting gel was stiffer than when sprayed without gas dispersant.