Effects of saline submersion at body temperature on airway supportive devices including a novel nasopharyngeal device produced using 3D-printing.

PURPOSE: This study investigated dimension changes of various nasopharyngeal airways, including a novel self-supporting device, after saline submersion at body temperature to simulate in-vivo use. Dimension changes over time may reduce efficacy during long-term use and require sizing adjustments or limits on duration of use. MATERIALS AND METHODS: Cuffless Covidien endotracheal tubes, pediatric Rusch fixed flange polyvinyl chloride nasal airway tubes, pediatric Rusch Robertazzi style Mediprene nasal airway tubes, and novel silicone elastomer self-supporting nasopharyngeal airways were fully submerged in 0.9 % normal saline solution incubated at 37 degrees Celsius for 15 days. All devices had tube length and wall thickness measured after 0, 1, 2, 3, 4, 5, 10, and 15 days. The 95 % confidence intervals of tube dimensions at each date were compared with the 95 % confidence intervals at day 0. RESULTS: The Covidien ET tube, Rusch PVC NPA, and ssNPA tube lengths and wall thicknesses did not change significantly over 15 days. The Rusch Mediprene NPAs had a statistically significant increase in length starting at day 1 and wall thickness at day 2. CONCLUSIONS: The novel ssNPA did not expand in the in-vitro environment, supporting its safety for extended use. The PVC NPA and ET tube dimensions also remained stable. However, the Rusch Mediprene NPAs had significant length expansion after 1 day of submersion, indicating a considerable risk of expansion during extended use with potential implications for patient care. Silicone and PVC NPA dimensions remained stable when saturated, indicating these materials may be more appropriate for extended use.

Practice Patterns in Sternal Closure and Evaluation of Adoption of a Novel Sternal Closure Device.

OBJECTIVE: The technique for sternal closure has remained largely unchanged owing to the efficacy, simplicity, and low cost of stainless-steel sternal wires. Despite their ubiquity, several other closure devices designed to address the complications associated with sternal wires such as sternal bleeding and dehiscence have become popular. We have developed a novel sternal closure device that reduces sternal bleeding and dehiscence. This study quantifies the use of currently available sternal closure devices and determines predicted uptake of the novel device. METHODS: An electronic survey, designed to determine practice patterns for sternal closure, was distributed to 70 US cardiac surgeons. The survey included a discrete choice section in which surgeons evaluated relative value of device attributes including cost, ease of emergent sternal reentry, and dehiscence risk. RESULTS: There were 70 surgeons from 30 states who completed the survey. The most frequent means of sternal closure was straight sternal wires (35.8%), followed by straight sternal wires plus figure-of-8 sternal wires (18.1%), double wires (10.9%), plates (10.2%), and other (25%). The relative utilization shifted from sternal wires to sternal plates as the risk for dehiscence increased. The adoption of the novel closure device was estimated at 34.6%. CONCLUSIONS: The standard stainless-steel sternal wire remains the most common means of sternal reapproximation, but its utilization is lower in patients at high risk for sternal dehiscence. Based on this survey, there is acceptance in the community for a novel sternal closure device designed to address the limitations of traditional sternal closure methods.

Mechanical Analysis of a Novel Sternal Closure System in Static Tensile Loading.

The most common means of sternal closure after sternotomy is stainless steel wire cerclage. These wires, while inexpensive and simple in design, are known to be associated with low strength and sternal dehiscence. In this biomechanical analysis, we compare single sternal wires, double sternal wires, and a novel sternal closure device we have designed to mitigate sternal dehiscence. The device uses polymer grommets at the sternal interfaces to distribute load over a large surface area of bone. Samples of each closure device were installed in a bone model and distracted at a rate of 10 mm/min while tensile forces were continuously measured and compared. Single wires generated the lowest stiffness and strength values, followed by the double wires. The novel device demonstrated significantly higher stiffness and strength at all displacements compared with the single and double wires. Clinical use of this device may result in meaningful reduction in complications associated with the use of standard sternal wires such as sternal separation and fracture.

Development and Testing of an Anatomic in vitro Kidney Model for Measuring Intrapelvic Pressure During Ureteroscopy.

OBJECTIVES: To create an in vitro anatomic bench model that can mimic in vivo intrapelvic pressure (IPP) during ureteroscopy (URS) and compare it against existing in vivo and ex vivo data. METHODS: A silicone kidney model (Simagine Health) that permits intrarenal endoscopic navigation was engineered to have a fluid-tight seal for the ureteral opening and a Tuohy-Borst valve in the renal pelvis incorporating a 0.2 mm pressure sensor (Opsens). To calibrate the model, a Cobra ureteroscope (Wolf) was inserted to the pelvis with 200cmH2O irrigation, and the valve adjusted until an IPP of 54cmH2O was obtained (prior human data). All experiments were conducted with a laser fiber in the working channel, with and without ureteral access sheaths (UAS) (11/13F, 13/15F) at irrigation setting of 61, 102, 153, and 193cmH2O using an automated system (Rocamed). Study outcome was mean steady-state IPP for each UAS/irrigation condition. RESULTS: Fluid leakage through the Tuohy-Borst valve, which could be adjusted, was critical to simulate ureteric outflow during URS. IPP values for each condition corresponded with data from in vivo and ex vivo models. In the no UAS condition, IPP increased with increasing irrigation pressures, and surpassed 40cmH2O when ≥153cmH2O. When using a UAS, IPP was below 40cmH2O for all irrigation pressures. CONCLUSIONS: An in vitro kidney model can simulate in vivo and ex vivo IPP profiles, and be tailored to different conditions by controlling fluid outflow. This bench model can be useful for testing of new technologies and their impact on IPP.

Multi-Bevel Needle Design Enabling Accurate Insertion in Biopsy for Cancer Diagnosis.

OBJECTIVE: To obtain definitive cancer diagnosis for suspicious lesions, accurate needle deployment and adequate tissue sampling in needle biopsy are essential. However, the single-bevel needles in current biopsy devices often induce deflection during insertion, potentially causing lesion missampling/undersampling and cancer misdiagnosis. This study aims to reveal the biopsy needle design criteria enabling both low deflection and adequate tissue sampling. METHODS: A novel model capable of predicting needle deflection and tissue deformation was first established to understand needle-tissue interaction with different needle tip geometries. Experiments of needle deflection and ex-vivo tissue biopsy were conducted for model validation. RESULTS: The developed model showed a reasonably good prediction on the correlation of needle tip type vs. the resultant needle deflection and tissue sampling length. A new multi-bevel needle with the tissue separation point below the needle groove face has demonstrated to be an effective design with an 87% reduction in deflection magnitude and equivalently long tissue sampling length compared to the current single-bevel needle. CONCLUSION: This study has revealed two critical design criteria for biopsy needles: 1) multiple bevel faces at the needle tip can generate forces to balance bending moments during insertion to enable a low needle deflection and 2) the tissue separation point should be below the needle groove face to ensure long tissue sampling length. SIGNIFICANCE: The developed methodologies and findings in this study serve as proof-of-concept and can be utilized to investigate various biopsy procedures to improve cancer diagnostic accuracy as well as other procedures requiring accurate needle insertion.

Single-use flexible ureteroscopes: how to choose and what is around the corner?

PURPOSE OF REVIEW: The pace of technology development with single-use endoscopy has led to a range of disposable ureteroscopes. We review the development of single-use scopes, deconstruct the basic design and functional characteristics of available devices, and discuss future directions for next-generation platforms. RECENT FINDINGS: Currently available devices are differentiated on the basis of several core features. The optical, deflection and irrigation characteristics are marginally different with no device clearly superior in every category. Studies comparing single-use ureteroscopes in patients linked to outcomes are limited. The incorporation of next-generation technologies into these platforms include sensors to monitor intrarenal pressure and temperature, suction of fluid and fragments, and computer vision for artificial intelligence. SUMMARY: Each ureteroscope has specific features that may be advantageous in different circumstances. Single-use devices could transform the ureteroscope from a visual conduit to a transformative surgical instrument that improves outcomes and reduces complications.

Biaxial test and hyperelastic material models of silicone elastomer fabricated by extrusion-based additive manufacturing for wearable biomedical devices.

Biaxial tensile testing of the silicone elastomer fabricated by additive manufacturing (AM) for wearable biomedical devices is presented. Silicone elastomer has unique mechanical properties ideal for stretchable parts in wearable biomedical devices. Biaxial tensile testing, in comparison to the uniaxial tensile and compression tests, is more representative for materials with large, multidirectional stretch. This study investigates the experimental setup and methods to measure and characterize mechanical properties of AM solid and porous silicone elastomer sheets on equi-biaxial stretch (with the stretch ratio up to 2). Four hyperelastic material models were applied to characterize the AM silicone sheet and evaluated through the finite element analysis (FEA) to quantify the fit to biaxial tensile test results. The Yeoh model with C10 = 80.7 kPa, C20 = -2.11 kPa, and C30 = 0.22 kPa has the best match to the experimentally measured stress-strain curve as well as the force and strain in FEA. This study demonstrates that the effects of raster angle and thickness are insignificant in the stress-strain curve of an AM silicone elastomer with solid cross-section. This study also demonstrates that AM can fabricate anisotropic porous silicone elastomer parts with different stiffness in x- and y-directions.

Needle deflection and tissue sampling length in needle biopsy.

This study investigates the effect of needle tip geometry on the needle deflection and tissue sampling length in biopsy. Advances in medical imaging have allowed the identification of suspicious cancerous lesions which then require needle biopsy for tissue sampling and subsequent confirmatory pathological analysis. Precise needle insertion and adequate tissue sampling are essential for accurate cancer diagnosis and individualized treatment decisions. However, the single-bevel needles in current hand-held biopsy devices often deflect significantly during needle insertion, causing variance in the targeted and actual locations of the sampled tissue. This variance can lead to inaccurate sampling and false-negative results. There is also a limited understanding of factors affecting the tissue sampling length which is a critical component of accurate cancer diagnosis. This study compares the needle deflection and tissue sampling length between the existing single-bevel and exploratory multi-bevel needle tip geometries. A coupled Eulerian-Lagrangian finite element analysis was applied to understand the needle-tissue interaction during needle insertion. The needle deflection and tissue sampling length were experimentally studied using tissue-mimicking phantoms and ex-vivo tissue, respectively. This study reveals that the tissue separation location at the needle tip affects both needle deflection and tissue sampling length. By varying the tissue separation location and creating a multi-bevel needle tip geometry, the bending moments induced by the insertion forces can be altered to reduce the needle deflection. However, the tissue separation location also affects the tissue contact inside the needle groove, potentially reducing the tissue sampling length. A multi-bevel needle tip geometry with the tissue separation point below the needle groove face may reduce the needle deflection while maintaining a long tissue sampling length. Results from this study can guide needle tip design to enable the precise needle deployment and adequate tissue sampling for the needle biopsy procedures.

Development and evaluation of a high-fidelity lactation simulation model for health professional breastfeeding education.

BACKGROUND: A key reason for premature cessation of breastfeeding is inadequate support from healthcare providers. Most physicians and nurses do not feel confident in their ability to support families with breastfeeding initiation or maintenance. Increasing health professional confidence in clinical lactation skills is key to improving maternal and child health outcomes. High-fidelity (realistic) simulators encourage learner engagement, resulting in increased clinical skills competency, confidence, and transfer to patient care. Lactation educators teach with low-fidelity cloth and single breast models. There are no high-fidelity breast simulators for health professional education in clinical lactation. DEVELOPMENT AND EVALUATION OF A HIGH-FIDELITY LACTATION SIMULATION MODEL: In this commentary we describe the development of a high-fidelity Lactation Simulation Model (LSM) and how physician residents, nurse-midwifery students, and clinical lactation experts provided feedback on LSM prototypes. LIMITATIONS: The user-testing described in this commentary does not represent comprehensive validation of the LSM due to small sample sizes and the significant conflict of interest. CONCLUSION: For breastfeeding rates to improve, mothers need support from their nurses, midwives, pediatricians, obstetricians and gynecologists, and all healthcare staff who interact with pregnant and lactating women. Clinical education with high-fidelity breastfeeding simulators could be the ideal learning modality for trainees and hospital staff to build confidence in clinical lactation skills. The ability of a high-fidelity breastfeeding simulator to increase a learner's lactation knowledge and psychomotor skills acquisition, retention, and transfer to patient care still needs to be tested.

Simplifying Arterial Coupling in Microsurgery-A Preclinical Assessment of an Everter Device to Aid with Arterial Anastomosis.

BACKGROUND: A novel arterial everter device was engineered to simplify microvascular coupling of arteries by reliably securing the stiff, muscular wall of arteries over coupler pins. We compare microvascular coupling with the everter device to manual suturing for arterial anastomoses in a live large animal model. MATERIALS AND METHODS: In this preliminary study, bilateral external femoral arteries of five male swine were exposed and sharply divided. Arteries were anastomosed using either interrupted sutures (n = 5) or the everter device and Synovis Coupler (n = 5). The efficiency in engaging coupler pins, the time taken to perform the anastomosis, and vessel patency immediately post-op and at 1-week postanastomosis were evaluated. Vessel wall injury and luminal stenosis were compared between groups using histomorphometric analyses. RESULTS: On an average, 80% of coupler pins engaged the vessel walls after a single pass of the everter. The average time to perform the anastomosis was significantly less when using the everter/coupler compared with manual suturing (6:35 minutes versus 25:09 minutes, p < 0.001). Immediately post-op, 100% patency was observed in both groups. At 1 week post-op, four of five (80%) of coupled arteries and all five (100%) of hand-sewn arteries were patent. The degree of arterial wall injury, neointimal formation, and luminal stenosis for patent arteries were similar between groups. CONCLUSIONS: Successful arterial anastomoses using the everter device with the Synovis Coupler was easier and significantly more efficient when compared with a standard hand-sewn technique. Both techniques had acceptable patency rates and similar effects on the vessel wall and intima.