Microfluidic Thermal Flowmeters for Drug Injection Monitoring

This paper presents a microfluidic thermal flowmeter for monitoring injection pumps, which is essential to ensure proper patient treatment and reduce medication errors that can lead to severe injury or death. The standard gravimetric method for flow-rate monitoring requires a great deal of preparation and laboratory equipment and is impractical in clinics. Therefore, an alternative to the standard method suitable for remote, small-scale, and frequent infusion-pump monitoring is in great demand. Here, we propose a miniaturized thermal flowmeter consisting of a silicon substrate, a platinum heater layer on a silicon dioxide thin-membrane, and a polymer microchannel to provide accurate flow-rate measurement. The present thermal flowmeter is fabricated by the micromachining and micromolding process and exhibits sensitivity, linearity, and uncertainty of 0.722 mW/(g/h), 98.7%, and (2.36 ± 0.80)%, respectively, in the flow-rate range of 0.5-2.5 g/h when the flowmeter is operated in the constant temperature mode with the channel width of 0.5 mm. The measurement range of flow rate can be easily adjusted by changing the cross-sectional microchannel dimension. The present miniaturized thermal flowmeter shows a high potential for infusion-pump calibration in clinical settings.

User-Centered Design: Developing the RELI Delivery System - a Low-Cost, Non-Electric, Pneumatic Infusion Pump

Purpose

Infusion pumps are the preferred method for intravenous delivery of drugs and fluids, and an essential tool in health facilities. Their high cost, complexity and reliance on electricity pose serious challenges to wide-spread use, availability and access in low- and middle-income countries. PATH developed the RELI Delivery System (RELI), a low cost, non-electric infusion pump to address these challenges. Input collected from fifty-nine newborn and maternal care providers and from seven national level decision makers in Uganda was used to guide product development, further informing product design requirements, and optimal design features to best serve their needs.

Methods

A formative evaluation following a mixed methods approach including focus group discussions (FGDs), stakeholder interviews, and observations was used to collect data from end users.

Results

Stakeholders provided critical input on the RELI prototype design features, safety criteria, and contexts of use of infusion pumps, as well as recommendations for design refinements. Infusion systems are greatly needed but not readily available and their use is limited to well-resourced higher level facilities, even though the need is high in non-tertiary care hospital where patient volume is high, resources are scarce, power is inconsistent, and facilities are understaffed and overcrowded. Users expressed a need for an affordable and simple device with an intuitive user interface, clear instructions for use, and basic safety features.

Conclusion

The study provided important guidance for further design refinements based on input from respondents and confirmed the need for robust, affordable, infusion pumps that meet the requirements for use in low-resource settings.

Diagnosis and Management of Acute Heart Failure in Sub-Saharan Africa

PURPOSE OF REVIEW

Acute heart failure (AHF) is a common emergency presentation in Sub-Saharan Africa (SSA). In the current review, we present the most recent data on the epidemiology of AHF in SSA and discuss recommended approaches to management in resource-limited settings, with a particular focus on primary and secondary facilities (e.g., health centers and district hospitals), where these patients often present.

RECENT FINDINGS

AHF in SSA is most often due to hypertension, cardiomyopathies, and rheumatic heart disease. The etiology of AHF may be different in rural as compared with urban settings. Diagnostic tools for AHF are often lacking in SSA, especially at the first-level facilities. Point-of-care ultrasound (POCUS) and biomarker tests, such as brain natriuretic peptide (BNP), offer promise in helping to mitigate diagnostic challenges. POCUS can also help distinguish among types of heart failure and prompt the correct treatment strategy. Many of the drugs and equipment commonly used to treat AHF in resource-rich settings are lacking in SSA. However, some adaptations of commonly available materials may provide temporary alternatives. The epidemiology of AHF in SSA differs from that of high-income settings. Management of AHF at the first-level facility in SSA is an important and understudied problem. Simplified diagnostic and treatment algorithms rooted in knowledge of the local epidemiology should be developed and tested as part of broader efforts to combat cardiovascular disease in SSA.

Syringe infusion pump with absolute piston displacement control

A vast majority of syringe pumps operate on stepper motors, which limits their effectiveness for precision fluid delivery using estimation algorithms. Such a system also hampers the ability to ascertain if the infusion or aspiration instruction has been correctly carried out in the event of power interruptions. To address this issue, a linear servo based actuator system is described to provide absolute indications of the plunger position. System performance in terms of linearity and reliability of plunger translation were verified using a camera tracking system with syringe capacities ranging from 3 to 50 ml and at syringe plunger speeds ranging from 1 to 6.6 mm/s when distilled water was used as the medium. In investigations involving more viscous liquids, the system revealed similarly linear characteristics with 50% glycerol-water (v/v), but cyclical stick-slip behavior with Freund's adjuvant.