Event Of Device Failure Research Articles

In Silico Evaluation of a Self-powered Venous Ejector Pump for Fontan Patients.

The Fontan circulation carries a dismal prognosis in the long term due to its peculiar physiology and lack of a subpulmonic ventricle. Although it is multifactorial, elevated IVC pressure is accepted to be the primary cause of Fontan's high mortality and morbidity. This study presents a self-powered venous ejector pump (VEP) that can be used to lower the high IVC venous pressure in single-ventricle patients. A self-powered venous assist device that exploits the high-energy aortic flow to lower IVC pressure is designed. The proposed design is clinically feasible, simple in structure, and is powered intracorporeally. The device's performance in reducing IVC pressure is assessed by conducting comprehensive computational fluid dynamics simulations in idealized total cavopulmonary connections with different offsets. The device was finally applied to complex 3D reconstructed patient-specific TCPC models to validate its performance. The assist device provided a significant IVC pressure drop of more than 3.2mm Hg in both idealized and patient-specific geometries, while maintaining a high systemic oxygen saturation of more than 90%. The simulations revealed no significant caval pressure rise (< 0.1mm Hg) and sufficient systemic oxygen saturation (> 84%) in the event of device failure, demonstrating its fail-safe feature. A self-powered venous assist with promising in silico performance in improving Fontan hemodynamics is proposed. Due to its passive nature, the device has the potential to provide palliation for the growing population of patients with failing Fontan.

On-Orbit Implementation of Discrete Isolation Schemes for Improved Reliability of Serial Communication Buses

Serial communication buses are used in electronic systems to interconnect sensors and other devices, but two of the most widely used protocols, i.e., interintegrated circuit (I2C) and serial peripheral interface (SPI), are vulnerable to bus-wide failure if even one device on the bus malfunctions. For aerospace applications demanding increasingly more distributed processing and sensing capability, the compounding risk to system reliability as device count scales becomes a limiting factor in mission scope, performance, and lifetime. We propose a simple external circuit to be added to each node on a communication bus that automatically isolates the node in the event of device failure. By automatically isolating failed devices, the integrity of the bus is preserved without requiring additional signals or processing overhead from the host controller. In this article, I2C and SPI isolation circuits are simulated, fabricated, and experimentally verified to be effective at preserving bus integrity in the event of peripheral device failure. The isolation circuits were integrated into three spacecraft for the successful NASA V-R3x mission and found to significantly improve system reliability by eliminating single-point failure modes of the I2C and SPI buses. The developed protection schemes are a valuable tool for decoupling system reliability from serial bus device count and can readily be integrated into the existing aerospace systems.

A Substrate-Less Microwave Power-Combining Module Utilizing Ridge Gap Waveguide

This letter presents the development of a microwave module that does not require a transition substrate to interface with the ridge gap waveguide (RGW). The RGW-to-chip transition is implemented on an all-metal structure using traditional computer numerical control machining and electrodischarge machining. The fabricated module is self-packaged, and the chip carrier assembly allows for quick monolithic microwave integrated circuit substation/exchange in the event of device failure. The designed module operates between 11 and 14.5 GHz, and the simulation and measured results are compared.

Altitude Illness on Mt. Rainier—Incidence and Climbers’ Cognizance

Reliance on Technology Among Climbers on Mount Rainier David C. Hile, MD; Jessica J. Walrath, MD; Aaron S. Birch, MD; Lisa M. Hile, MD Madigan Army Medical Center, Tacoma, WA, Yale-New Haven Hospital, New Haven, CT Objective.—Thousands of people set out daily to climb the world’s highest mountains in hopes of summiting. Although many 3000-m summits are accessible in favorable weather, conditions may turn calamitous quickly, requiring practiced navigation or rescue. Owing to the portability and low cost of many technological devices, many climbers have eschewed map and compass navigation. We sought to evaluate climbers’ reliance on technologic devices, as well as their effectiveness and reliability for rescue. Methods.—This survey study evaluated a convenience sample of climbers and hikers who arrived at Camp Muir, Mount Rainier (10,188 feet). Investigators ascended on 6 separate dates to the study site to collect data. The primary outcome evaluated was the percentage of climbers relying on a technologic device for rescue. Results.—Two hundred forty-four of 308 climbers (79%) brought some technologic means for rescue. However, only 133 (43%) had a nontechnological backup plan in event of device failure. Therefore, 57% relied solely on the functioning of their devices in a rescue situation. Of the 102 climbers who relied solely on a cell phone as their means of rescue, 49 (48%) had service at the time of the survey. Thirty-three of 308 (11%) reported that they had required a technologic means of rescue in the past, most commonly an avalanche beacon (n 1⁄4 13). For the 24 rescue devices that failed, the most common reasons were dead batteries in global positioning satellite equipment and lack of cell phone service. Conclusions.—Reliance on technological devices is becoming commonplace among climbers on Mount Rainier and largely replacing map and compass orienteering. The lack of reliable service for these devices as well as their failures among climbers who have had to use a rescue device in the past is, however, alarming.

Power-Injectable Ports: Safety during Placement, Therapeutic use, and Contrast Administration during Computed Tomography Procedures

To determine the safety of power-injectable ports during placement, therapeutic use, and administration of intravenous contrast material using automated mechanical injectors. This retrospective, single institution study examined all patients undergoing placement of a power-injectable port between May 1, 2006 and June 30, 2010, with follow-up data collected through October 31, 2010. Electronic records and PACS were searched for patient demographics, placement indication, device placed, placement site, attending operator, and complications. The number of CECT scans performed for patients with indwelling ports, rate of port access for such studies, and contrast extravasation or device failure events during power injection of contrast were recorded and compared to the results of all other methods of venous access for CECT scans. In total, 313 ports were placed in 307 patients. Device dwell time ranged from 3 to 1506 days with a mean of 577. A total of 20 (6.5%) complications were identified during the study period, all of which were late. There was no statistically significant difference in complication rates between five attending operators. Patients with ports underwent 676 CECT scans during which the port was injected 142 times (20.9%). Neither extravasation nor device failure occurred during any scan, yielding no statistically significant difference when compared to the results of other venous access methods. Power-injectable tunneled catheters with attached subcutaneous ports are safe with low rates of complication during placement and dwell time. Power injection of contrast through these ports may be as safe as power injection using other venous access methods.

A Framework for Good Practice: Managing Failures in a Cochlear Implant Service

Cochlear implants can provide the recipient and their family with wonderful outcomes in terms of their improved access to sound and to speech. However the experience of a cochlear implant failing is distressing for all concerned. Clinicians endeavour to ensure that the process of confirming the failure, re-implantation and subsequent rehabilitation is as smooth as possible. In order to benefit from each others experience, a working party of cochlear implant centre coordinators and representatives from the Ear Foundation met on a number of occasions to draw up a protocol which could be used widely throughout the British Cochlear Implant Group. The protocol indicates quality standards of clinical care to be used in the event of device failure.