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Review Article

J. Med. Devices. 2019;13(2):020801-020801-6. doi:10.1115/1.4042794.

Developed countries struggle with high healthcare spending, and cost is often cited as a barrier to the introduction of new patient care technologies. The core objective of this review article is to help familiarize medical technology innovators with trends in the health economic environment and the implications for the adoption of new technologies. We review and discuss this topic in language accessible to medical technology innovators. We assess macrolevel developments in healthcare spending and highlight measures already taken to control spending. We discuss practical implications for anyone involved in healthcare innovation. Two observations are central to this discussion: (1) the U.S. spends significantly more on healthcare per capita than any other developed country; (2) across developed countries, healthcare spending has risen steadily over the past two decades. Nevertheless, higher spending has not always led to improvements in health. As a result, innovators need to be prepared to navigate an outcomes-oriented and value-based environment that is being defined by the emerging requirements of various healthcare stakeholders. Practically, new products should aim to improve health outcomes at a cost deemed “good value” and/or reduce cost for one or multiple stakeholders. Opportunities also exist for tools that enable cost/outcomes tracking, which will help demonstrate value to providers, insurers, and patients.

Commentary by Dr. Valentin Fuster

Research Papers

J. Med. Devices. 2019;13(2):021001-021001-9. doi:10.1115/1.4042599.

Many medical conditions, including sensory processing disorder (SPD), employ compression therapy as a form of treatment. SPD patients often wear weighted or elastic vests to produce compression on the body, which have been shown to have a calming effect on the wearer. Recent advances in compression garment technology incorporate active materials to produce dynamic, low bulk compression garments that can be remotely controlled. In this study, an active compression vest using shape memory alloy (SMA) spring actuators was developed to produce up to 52.5 mmHg compression on a child's torso for SPD applications. The vest prototype incorporated 16 SMA spring actuators (1.25 mm diameter, spring index = 3) that constrict when heated, producing large forces and displacements that can be controlled via an applied current. When power was applied (up to 43.8 W), the prototype vest generated increasing magnitudes of pressure (up to 37.6 mmHg, spatially averaged across the front of the torso) on a representative child-sized form. The average pressure generated was measured up to 71.6% of the modeled pressure, and spatial pressure nonuniformities were observed that can be traced to specific garment architectural features. Although there is no consistent standard in magnitude or distribution of applied force in compression therapy garments, it is clear from comparative benchmarks that the compression produced by this garment exceeds the demands of the target application. This study demonstrates the viability of SMA-based compression garments as an enabling technology for enhancing SPD (and other compression-based) treatment.

Commentary by Dr. Valentin Fuster
J. Med. Devices. 2019;13(2):021002-021002-10. doi:10.1115/1.4043016.

We present novel medical devices for safe surgical puncturing, in particular a cannula for the treatment of retinal vein occlusion (RVO). This passive mechanical device has an adjustable stroke and exerts a puncturing force independent of operator applied displacement. The innovative feature of this tool is that puncturing stroke is decoupled from operator input thereby minimizing the possibility of overpuncturing. This is achieved using our concept of stability programming, where the user modifies the mechanism strain energy as opposed to imposing direct displacement which is the case for standard bistable mechanisms. Ultra-fast laser three-dimensional (3D) printing is used to manufacture the needle in glass. A microfluidic channel is integrated into the needle tip for drug injection. Numerical simulations and experimental measurements validate the mechanical stability behavior of the puncture mechanism and characterize its puncturing stroke and force.

Commentary by Dr. Valentin Fuster
J. Med. Devices. 2019;13(2):021003-021003-9. doi:10.1115/1.4043018.

Slip, or accidental loss, of grasped biological tissue can have negative consequences in all types of surgery (open, laparoscopic, robot-assisted). This work focuses on slip in robot-assisted surgery (RAS) with the goal of improving the quality of grasping and tool–tissue interactions. We report on a survey of 112 RAS surgeons, the results of which support the value of detecting and reducing slip in a variety of procedures. We conducted validation tests using a thermal slip sensor in a surgical grasper on tissue in vivo and ex vivo. The results of the survey and validation informed a user study to assess whether tissue slip feedback can improve performance and reduce effort in a phantom tissue manipulation task. With slip feedback, experienced subjects were significantly faster to complete the task, dropped tissue less (3% versus 38%), and experienced decreased mental demands and situational stress. These results provide motivation to further develop the sensor technology and incorporate it in robotic surgical equipment.

Commentary by Dr. Valentin Fuster

Technology Review

J. Med. Devices. 2019;13(2):024001-024001-10. doi:10.1115/1.4042795.

The aims of this study were (1) to identify research publications studying noninvasive electrocardiogram (ECG) monitoring devices, (2) to define and categorize current technology in noninvasive ECG recording, and (3) to discuss desirable noninvasive recording features for personalized syncope evaluation to guide technological advancement and future studies. We performed a systematic review of the literature that assessed noninvasive ECG-monitoring devices, regardless of the reason for monitoring. We performed an Internet search and corresponded with syncope experts and companies to help identify further eligible products. We extracted information about included studies and device features. We found 173 relevant papers. The main reasons for ECG monitoring were atrial fibrillation (n = 45), coronary artery disease (n = 10), syncope (n = 8), palpitations (n = 8), other cardiac diseases (n = 67), and technological aspects of monitoring (n = 35). We identified 198 devices: 5 hospital telemetry devices, 12 patches, 46 event recorders, 70 Holter monitors, 23 external loop recorders, 20 mobile cardiac outpatient telemetries, and 22 multifunctional devices. The features of each device were very heterogeneous. There are a large number of ECG-monitoring devices with different features available in the market. Our findings may help clinicians select the appropriate device for their patients. Since there are only a few published articles analyzing their usefulness in syncope patients, further research might improve their use in this clinical setting.

Commentary by Dr. Valentin Fuster

Technical Brief

J. Med. Devices. 2019;13(2):024501-024501-6. doi:10.1115/1.4042866.

This paper describes a novel percutaneous ultrasound gastrostomy (PUG) procedure and the CoapTech point-of-care ultrasound magnet-aligned gastrostomy (PUMA-G) device, which were developed to allow the placement of gastrostomy tubes by physicians across a variety of specialties, using ultrasound equipment found in many nonspecialized medical locations while consuming fewer resources. The current practice for the placement of gastrostomy tubes requires highly specialized equipment and trained physicians, which can delay the performance of the procedure or make it inaccessible in some locations. The PUMA-G device consists of an orogastric catheter with a balloon that encloses a magnetic bar at its distal end and an external, handheld magnet. The orogastric tube is passed through the mouth or the nose and into the stomach. The external magnet is then used to maneuver the balloon to the desired location in the stomach, with feedback and guidance from real-time ultrasound visualization. The novelty of this approach is the use of magnets to create the static compressive force needed for coaptation, in which the stomach is pushed flush against the abdominal wall, allowing ultrasound visualization of the entire gastrostomy tract (skin to stomach), safe cutaneous puncture, and guidewire-assisted placement of the gastrostomy tube. The development of the PUMA-G device has been aided by benchtop and simulation testing in addition to canine and human cadaver studies. The PUMA-G device was used successfully in 29 of 30 cadaver tests, with the one failure attributed to operator error and not the device. Further testing in live patients will assess the safety of the procedure, the speed with which it can be completed, the cost savings, and other benefits the device might offer over the existing gastrostomy procedures.

Commentary by Dr. Valentin Fuster

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