Accepted Manuscripts

John Valdovinos, J. Chris Bouwmeester and Pramod Bonde
J. Med. Devices   doi: 10.1115/1.4038221
Right ventricular dysfunction has limited the effectiveness of mechanical circulatory support therapy in some heart failure patients. Intravascular pumps can provide adequate circulatory support without the need for extensive operations. The development of an intravascular right ventricular assist device, called the cavo-arterial pump (CAP), is presented. Two prototypes of the CAP were developed to demonstrate the feasibility of providing adequate pulmonary support and to demonstrate the feasibility of using axial magnetic couplings for contactless torque transmission from the motor shaft to the pump impeller. The CAP utilizing a direct drive mechanism produced a maximum pressure of 100 mm Hg and a maximum flow of 2.25 L/min when operated at 24 kRPM. When a magnetic drive mechanism was used, the overall flow rate decreased due to a loss in torque transmission. The magnetic drive CAP was able to operate up to 18.5 kRPM and produce a maximum flow rate of 1.35 L/min and a maximum pressure difference of 40 mm Hg. These results demonstrate that the CAP produces sufficient output for partial circulatory support of the pulmonary circulation and that axial magnetic couplings can help to eliminate the sealing system needed to isolate the miniature motor and bearings from blood contact.
Tyler G Tuttle and Byron D. Erath
J. Med. Devices   doi: 10.1115/1.4038222
This manuscript presents the design of a mechanically-driven artificial speech device to be used by laryngectomees as an affordable alternative to an electrolarynx. Design objectives were based on feedback from potential end-users. The device implements a mainspring powered gear train that drives a striker. The striker impacts a suspended drum-like head, producing sound. When pressed against the neck, the head transmits sound into the oral cavity, allowing the user to produce intelligible speech. The dynamics of the vibrating head and sound pressure levels produced at the mouth were measured to compare performance between the device and a common, commercially-available electrolarynx. The results showed comparable performance and sound output.
Francesco Tessarolo, Sebastián Torres Montoya, Luis Miguel Ballesteros, Marta Rigoni, Federico Piccoli, Iole Caola, Patrizio Caciagli, Yesid Montoya and Giandomenico Nollo
J. Med. Devices   doi: 10.1115/1.4038145
Safety and efficacy issues are associated to reprocessing of single-use electrosurgical pencils (EPs), requiring methods for assessing the reprocessing protocol before clinical re-use. This study aimed at monitoring the surface characteristics of single-use electrosurgical pencils subjected to multiple clinical use and in-hospital reprocessing. A total of 24 single-use-labelled EPs were divided in five test groups and one control group. The test groups were subjected to a different number of clinical uses, ranging from one to five. A multi-technique approach based on optical stereomicroscopy, scanning electron microscopy, energy dispersive X-rays spectroscopy, differential scanning calorimetry and thermo-gravimetric analysis was applied. The silicon coating of the tip was significantly reduced and foreign bodies were occasionally found on reprocessed EPs. The amount of biological debris and chemical residuals increased with the number of reprocessing cycles in critical areas. The degradation temperature of the EP handle polymer showed a progressive significant reduction. Cable cord showed no modification after reprocessing. EP tip could undergo major surface modifications that can affect functionality. The efficacy of the reprocessing protocol in removing debris from the EP handle should be carefully assessed. Surface and thermal characteristics have to be considered for validating a reprocessing protocol of single-use labelled EP.
TOPICS: Temperature, X-rays, Coating processes, Coatings, Spectroscopy, Safety, Cables, Expandable polystyrene, Polymers, Scanning electron microscopy, Cycles, Differential scanning calorimetry, Silicon
Alexander H. Slocum Jr., Steven Reinitz, Shailly H. Jariwala and Douglas W. Van Citters
J. Med. Devices   doi: 10.1115/1.4037442
Intra-osseous (IO) needles are an easy and reliable alternative to intravenous (IV) access in the pre-hospital and emergency settings for treating patients in shock. The advantage of utilizing an IO is that secure, non-collapsible peripheral venous access can be obtained rapidly in critically ill patients. Placement of IO needles in the proximal tibia, humerus, or sternum however, requires knowledge of human anatomy and the requisite skill to position, align, and place the device. In the developing world this is not always available, and in the chaos of an in-hospital code, pre-hospital trauma, or a mass-casualty incident, even trained providers can have trouble correctly placing IVs or IOs. The Tib-Finder™ is an intuitive drill guide that significantly improves efficiency with which IOs can be placed in the proximal tibia. Here, we present the conceptualization, design, and creation of an alpha-prototype Tib-Finder™ drill guide in less than 90 days; initial validation was achieved through analysis of anthropometric measurements of human skeletons, and usability studies were performed using untrained volunteers and mannequins. The Tib-Finder™ is intended to provide first responders and medical personnel, in the first world and the developing world, a way to accurately and repeatably locate the proximal tibia, and achieve safe, rapid intra-vascular access in critically ill patients. Further, it eliminates the need for direct contact between patients and caregivers and improves the ease-of-use of IO devices by first responders and healthcare providers.
TOPICS: Design, needles, Drills (Tools), Developing nations, Engineering prototypes, Shock (Mechanics), Chaos, Health care, Body systems and structures, Biomedicine, Emergencies
Review Article  
Laurence Nouaille, M. Amine Laribi, Carl A. Nelson, Said Zeghloul and Gerard Poisson
J. Med. Devices   doi: 10.1115/1.4037053
Introduction This paper deals with the survey of kinematic structures adapted to specific medical robots: minimally invasive surgery and tele-echography. The large diversity of kinematic architectures that can be found in medical robotics leads us to perform a statistical analysis to inform and guide design of medical robots. Safety constraints and some considerations in design evolution of medical robots are presented in this paper. Methods First, we describe the spectrum of medical robots in minimally invasive surgery and tele-echography applications and particularly the variety of kinematic architectures used. We present the robots and their kinematic architectures and highlight differences that occur in each medical application. We perform a statistical analysis which can serve as a resource in topological synthesis for each specific medical application. Safety is an important specification in medical robotics, and for that reason we show the means used to take into account this constraint. Conclusion This study demonstrates that the nature of medical robots implies specific requirements leading to different kinematic structures. The statistical analysis gives information on choice of kinematic structures for medical applications (minimally invasive surgery and echography). The safety constraint as well as the interaction between doctor and robot leads to investigate new mechanical solutions to enhance medical robot safety and compliance. We expect that this paper will serve as a significant resource and help the design of future medical robots.
TOPICS: Kinematics, Robots, Surgery, Biomedicine, Safety, Design, Architecture, Statistical analysis, Robotics
Design Innovation Paper  
F. Mark Payne, Tony Connell and Jacob Rice
J. Med. Devices   doi: 10.1115/1.4030812
Background: Tissue expanders are used in breast reconstruction after mastectomy to create a space for placement of permanent breast implants. The AeroForm™ Tissue Expander, developed by AirXpanders™ Inc., utilizes carbon dioxide released from an internal reservoir to inflate the expander. The released gas is contained within a high barrier material pre-formed into a breast shaped shell of the desired volume. During patient travel to higher altitude, a partially inflated expander will increase in volume proportionately to the gas fill volume. At volume levels near full, expansion is governed by the compliance of the inner gas barrier and silicone shell. Therefore, the assessment of the expander performance at altitude consists of the analysis of two operating regimes. The first regime is fill levels < 70% full where the implant, when exposed to cabin pressure, expands without significantly stressing the inner gas barrier. The second is fill levels ~>70% where the response of the inner gas barrier is important, both in terms of structural capability and determination of the volume increase. We assessed the impact of pressurized flight on expander performance in both operating regimes. Findings: The volume increase associated with altitude increase to 8000 feet (maximum cabin altitude per FAA) is typically within the range administered during post-operative fills of saline expanders. Although assessment must be conducted by a clinician, a patient can be typically expected to tolerate the increased volume with some minor discomfort, such as a feeling of tightness. At higher fill levels, the structural capability of shell has been demonstrated to withstand the additional pressure loading. At these fill levels, the expander does not expand as much, due to the structural restraint of the shell. To date, 7 subjects have flown with the expander in situ during clinical trials. All subjects were required to temporarily cease dosing up to two weeks prior. Flight travel was completed uneventfully and they reported discomfort levels ranging from none to moderate. The recommendation to cease dosing two weeks prior to flying was made to allow the expected 1 cc per day of CO2 permeation to occur, which will result in slight deflation to accommodate for the expansion of the CO2 when flying. As expected, subjects reported a sensation of pressure upon ascent which subsided on descent.
TOPICS: Biological tissues, Carbon dioxide, Shells, Pressure, Flight, Reservoirs, Silicones

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