Although intravenous therapy (IV) is one of the most frequently utilized approaches for fluid delivery in modern healthcare, it is associated with some form of complication up to 40% of the time. While many complications are minor, occlusion and extravasation can prevent the delivery of a needed fluid-based intervention or cause delivery into the subdermal space, which can lead to distributed tissue damage and necrosis. To address this need, this group developed the IV patency monitoring device (IVP) to generate and analyze a small pulse wave within the IV fluid. The study hypothesis was that changes in the IV’s communication with the blood stream could be detected as an alteration in this signal. This study investigated wave characteristics generated by the IVP in a benchtop tissue phantom. Results demonstrated that wave characteristics change detectably between simulated patent communication with a simulated blood stream and states of extravasation or occlusion. Future work will focus on improved detection methods and integrating a real-time alert system, which will better prepare the IVP for clinical translation and impact.

Introduction: Portable oxygen concentrators (POCs) are medical devices that use physical means to separate oxygen from the atmosphere to produce concentrated, medical-grade gas. Providing oxygen to low-resources environments, such as austere locations, military combat zones, rural Emergency Medical Services (EMS), and during disasters, becomes expensive and logistically intensive. Recent advances in separation technology have promoted the development of POC systems ruggedized for austere use. This review provides a comprehensive summary of the available data regarding POCs in these challenge environments. Methods: PubMed, Google Scholar, and the Defense Technical Information Center were searched from inception to November 2021. Articles addressing the use of POCs in low-resource settings were selected. Three authors were independently involved in the search, review, and synthesis of the articles. Evidence was graded using Oxford Centre for Evidence-Based Medicine guidelines. Results: The initial search identified 349 articles, of which 40 articles were included in the review. A total of 724 study subjects were associated with the included articles. There were no Level I systematic reviews or randomized controlled trials. Discussion: Generally, POCs are a low-cost, light-weight tool that may fill gaps in austere, military, veterinary, EMS, and disaster medicine. They are cost-effective in low-resource areas, such as rural and high-altitude hospitals in developing nations, despite relatively high capital costs associated with initial equipment purchase. Implementation of POC in low-resource locations is limited primarily on access to electricity but can otherwise operate for thousands of hours without maintenance. They provide a unique advantage in combat operations as there is no risk of explosive if oxygen tanks are struck by high-velocity projectiles. Despite their deployment throughout the battlespace, there were no manuscripts identified during the review involving the efficacy of POCs for combat casualties or clinical outcomes in combat. Veterinary medicine and animal studies have provided the most robust data on the physiological effectiveness of POCs. The success of POCs during the coronavirus disease 2019 (COVID-19) pandemic highlights the potential for POCs during future mass-casualty events. There is emerging technology available that combines a larger oxygen concentrator with a compressor system capable of refilling small oxygen cylinders, which could transform the delivery of oxygen in austere environments if ruggedized and miniaturized. Future clinical research is needed to quantify the clinical efficacy of POCs in low-resource settings.

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Investigations of fluidic oscillators, or sweeping jet actuators, have primarily been conducted within the incompressible flow regime, which limits the accuracy of estimating fluidic oscillator performance for compressible flows. The objective of this study was to evaluate the effects of gas compressibility on the performance of a fluidic oscillator. A commonly used fluidic oscillator geometry (the Bray geometry) was scaled to five different sizes, 3D printed, and tested over a range of air flow rates. High-speed Schlieren images captured the sweeping jet exiting the fluidic oscillators, and custom MATLAB algorithms were used to calculate the oscillation frequencies and angles. A spectral proper orthogonal decomposition (SPOD) method was used to identify and compare the mode structures within the flow fields. All the results were compared using dimensionless parameters to observe performance trends. The results showed that the oscillation frequencies were directly proportional to the flow rate, while the oscillation angles were inversely proportional to the flow rate, regardless of scale size. The angular velocities were not proportional to the flow rate or scale size and exhibited maxima within the evaluated ranges. For all scale sizes, the mode structures were symmetric across the centerlines of the fluidic oscillators and extended further beyond the fluidic oscillators at higher flow rates. These results enable the prediction of fluidic oscillator performance, which can significantly improve the design process for an application where a fluidic oscillator may be used, such as aerospace applications, power generation, heat exchangers, or medical devices.