Add-on Devices Research Articles

Reinforcing the role of the conventional C-arm - a novel method for simplified distal interlocking

BackgroundThe common practice for insertion of distal locking screws of intramedullary nails is a freehand technique under fluoroscopic control. The process is technically demanding, time-consuming and afflicted to considerable radiation exposure of the patient and the surgical personnel. A new concept is introduced utilizing information from within conventional radiographic images to help accurately guide the surgeon to place the interlocking bolt into the interlocking hole. The newly developed technique was compared to conventional freehand in an operating room (OR) like setting on human cadaveric lower legs in terms of operating time and radiation exposure.MethodsThe proposed concept (guided freehand), generally based on the freehand gold standard, additionally guides the surgeon by means of visible landmarks projected into the C-arm image. A computer program plans the correct drilling trajectory by processing the lens-shaped hole projections of the interlocking holes from a single image. Holes can be drilled by visually aligning the drill to the planned trajectory. Besides a conventional C-arm, no additional tracking or navigation equipment is required.Ten fresh frozen human below-knee specimens were instrumented with an Expert Tibial Nail (Synthes GmbH, Switzerland). The implants were distally locked by performing the newly proposed technique as well as the conventional freehand technique on each specimen. An orthopedic resident surgeon inserted four distal screws per procedure. Operating time, number of images and radiation time were recorded and statistically compared between interlocking techniques using non-parametric tests.ResultsA 58% reduction in number of taken images per screw was found for the guided freehand technique (7.4 ± 3.4) (mean ± SD) compared to the freehand technique (17.6 ± 10.3) (p < 0.001). Total radiation time (all 4 screws) was 55% lower for the guided freehand technique compared to conventional freehand (p = 0.001). Operating time per screw (from first shot to screw tightened) was on average 22% reduced by guided freehand (p = 0.018).ConclusionsIn an experimental setting, the newly developed guided freehand technique for distal interlocking has proven to markedly reduce radiation exposure when compared to the conventional freehand technique. The method utilizes established clinical workflows and does not require cost intensive add-on devices or extensive training. The underlying principle carries potential to assist implant positioning in numerous other applications within orthopedics and trauma from screw insertions to placement of plates, nails or prostheses.

The Overall Drag Losses for A Combination of Bodies

The objective of this work is to obtain better understanding of the flow over a combination of bluff bodies in close enough proximity to strongly interact with each other. This interaction is often beneficial in that the drag of the overall system is reduced. Proto-types for this problem come from tractor- trailer and missiles, and from various add-on devices designed to reduce their drag. Thus, an experimental investigation was carried out by placing conical frontal bodies having a base diameter of 0.65-cylinder diameter with different vertex angles (30°, 50°, 70°, and 90°). It was found that, the bluffer cone with 90° vertex angle gives the best minimum drag, which is 31% lower than the drag of the isolated cylinder. Also an interesting phenomenon was observed in that, the minimum drags for all combinations are obtained at the same gap ratio (i.e.at g/d2= 0.365).

Rear Add-on Device for Drag Reduction of Van Body Truck

In this work, to reduce the drag of a van body truck, an aerodynamic device is fixing on the aft-body with different angle of declination and shape of the wing. The effects of reducing drag are studied by the methods of Numerical Simulation. And then the mechanism is discussed. The paper selects four rear add-on devices with different obliquity by 5deg, 10deg, 15deg and 20deg. And the shape of the wing is defined as straight line and curve, respectively. Seen from the results of numerical simulation, the rear add-on device can reduce the drag effectively. When the declination angle is 15deg, the effect is the best and the drag of the truck model is reduced by 8.9%. Furthermore, when the add-on plate is changed from contouring with straight line into Witozinsky curve in the same declination angle, the drag can reduce about another 3%. With the optimum declination angle and wing shape, the drag of the truck model is reduced 11.98%.

Influence of Different Diffuser Angle on Sedan's Aerodynamic Characteristics

The aerodynamic characteristics have a great influence on the fuel economics and the steering stability of a high speed vehicle. The underbody rear diffuser is one of important aerodynamic add-on devices. The parameters of the diffuser, including the diffuser angle, the number and the shape of separators, the shape of the end plate and etc, will affect the underbody flow and the wake. Here, just the influence of the diffuser angle was investigated without separator and the end plate. The method of Computational Fluid Dynamics was adopted to study the aerodynamic characteristics of a simplified sedan with a different diffuser angle respectively. The diffuser angle was set to 0°, 3°, 6°, 9.8° and 12° respectively. The diffuser angle of the original model is 9.8°. The conclusions were drawn that when the diffuser angle increases, the underbody flow and especially the wake change greatly and the pressure change correspondingly; as a result, the total aerodynamic drag coefficients of car first decrease and then increases, while the total aerodynamic lift coefficients decrease.

Plume temperature emitted from metered dose inhalers

The temperature of the drug cloud emitted from a pressurised metered dose inhaler (pMDI) may result in patient discomfort and inconsistent or non-existent dose delivery to the lungs. The effects of variations in formulation (drug, propellant, co-solvent content) and device hardware (metering volume, actuator orifice diameter, add-on devices) upon the temperature of pMDI plumes, expressed as replicate mean minimum values (MMPT), collected into a pharmacopoeial dose unit sampling apparatus (DUSA), have been investigated. Ten commercially available and two development products, including chlorofluorocarbon (CFC) suspensions and hydrofluoroalkane (HFA) solutions or suspensions, were examined together with a number of drug products in late stage development and a variety of HFA 134a placebo pMDIs. Plume temperatures were observed to be lowest in the proximity of the product's actuator mouthpiece where rapid flashing and evaporation of the formulation's propellant and volatile excipients cause cooling. The ability to control plume temperature by judicious choice of formulation co-solvent content, metering volume and the actuator orifice diameter is identified. An ethanol based HFA 134a formulation delivered through a fine orifice is inherently warmer than one with 100% HFA 134a vehicle delivered through a coarse actuator orifice. Of the 10 commercial products evaluated, MMPTs ranged from −54 to +4 °C and followed the formulation class rank order, HFA suspensions < CFC suspensions < HFA solutions. For all systems examined it was possible to raise pMDI plume temperature to that of the ambient surroundings by use of an add-on or integrated spacer device.

Drag Reduction of Tractor-Trailers Using Optimized Add-On Devices

Tractor-trailers have a higher drag coefficient than other vehicles due to their bluff-body shape. Numerous add-on devices have been invented to help reduce drag and fuel consumption. The current research extends our previous idea of add-on humps and investigates their effect in conjunction with curved boat-tail flaps. Computational fluid dynamics in the form of unsteady Reynolds-averaged Navier–Stokes and detached-eddy simulations were used to determine viable design strategies. A 3D baseline computational model was constructed using an Ahmed body. Design optimization was applied on the new add-on devices. The results from the optimized design were shown to have a 50.9% reduction in drag coefficient.

New drag reduction design for tractor-trailers using CFD

Tractor-trailers have a higher drag coefficient than other vehicles due to their bluff-body shape. Over the years, numerous add-on devices have been invented to help reduce the drag. The current research investigates new add-on devices in the form of humps to reduce the base-drag of tractor-trailers. In the current investigation, computational fluid dynamics (CFD) in the form of unsteady Reynolds-averaged Navier-Stokes simulations is used to determine viable design strategies and optimise the new add-on device designs. A baseline model was built using an Ahmed body in both 2D and 3D. The predicted drag coefficient of the 3D Ahmed baseline model showed good agreement with experimental data. The 2D and 3D simulations with hump(s) showed some difference in drag reduction that was dependent on the hump geometry. A significant 3D effect existed. Results from the baseline validations as well as from simulations of tractor-trailer-like configurations with hump add-on devices are shown to demonstrate the drag reduction possible. While the hump is a conceptual design and may not be applied to full-size semi-truck trailers due to the height limit, it still offers a significant result which makes the applications on other smaller vehicles possible.

Evaluation of add-on devices for the prevention of phlebitis and other complications associated with the use of peripheral catheters in hospitalised adults: a randomised controlled study

The aim of this study was to assess the role of add-on devices for the prevention of phlebitis and other complications associated with the use of peripheral catheters. Patients admitted to an infectious diseases ward and requiring the insertion of a peripheral catheter for at least 24h were randomly allocated to be managed with or without add-on devices. Incidence of phlebitis and all complications were the primary outcomes. Extravasation, inadvertent withdrawal, obstruction and rupture were considered to be mechanical complications, and analysis was performed using survival methods. Of 683 evaluated catheters, 351 were allocated to the add-on device arm and 332 to the control arm. Despite randomisation, patients in the add-on device group were older (P=0.048), less likely to have human immunodeficiency virus (P=0.02) and more likely to have received antibiotics (P=0.05). After adjustment for these variables, the hazard ratio for phlebitis remained non-significant (hazard ratio: 0.95; 95% confidence interval: 0.7-1.3), but the risk of mechanical complications became lower in the add-on device arm (0.68; 0.5-0.94). This translated into a trend towards a lower risk of any complication (0.83; 0.67-1.01). The beneficial effect on mechanical or all complications was noticeable after six days of catheterisation. Add-on devices do not reduce the incidence of phlebitis but may prevent mechanical complications. However, the impact of add-on devices on the incidence of all complications is at most small and only apparent after the sixth day of catheter use.

Characterization of the Spray Velocities from a Pressurized Metered-Dose Inhaler

Pressurized metered dose inhalers (pMDIs) are widely used to deliver aerosolized medications to the lungs, most often to relieve the symptoms of asthma. Over the past decade, pMDIs have been modified in several ways to eliminate the use of chlorofluorocarbons in their manufacture while increasing efficacy. Numerical simulations are being used more frequently to predict the flow and deposition of particles at various locations, both inside the respiratory tract as well as in pMDIs and add-on devices. These simulations require detailed information about the spray generated by a pMDI to ensure the validity of their results. This paper presents detailed, spatially resolved velocity measurements of the spray emitted from salbutamol sulfate pMDIs obtained using optically triggered particle image velocimetry (PIV). Instantaneous planar velocity measurements were taken and ensemble-averaged at nine different times during the spray event ranging from 1.3 to 100 msec after a pneumatically controlled actuation. The mean spray velocities were shown to be bimodal in time, with two velocity peaks and velocity magnitudes found to be much lower than published data from instantaneous single point measurements. Planar velocity data at each time step were analyzed to produce prescriptive velocity profiles suitable for use in numerical simulations. Spray geometry data are also reported. Statistical comparisons from several thousand individual spray events indicate that there is no significant difference in measured velocity among (1) two brands of pMDI canisters, (2) two pMDIs of the same brand but having different lot numbers, and (3) a full pMDI versus an almost empty pMDI. The addition of a secondary air flow of 30 SLPM (to represent simultaneous inhalation and spray actuation) deflected the spray downward but did not have a significant effect on flow velocity. Further experiments with an added cylindrical spacer revealed that within the spacer, the spray direction and cone angle were altered, although the peak velocities remained similar.

Oral inhalation therapy: meeting the challenge of developing more patient-appropriate devices

Although oral inhalers have been mass produced for more than 50 years, there is a large body of literature in which evidence has been provided that patients either misuse their inhalers inadvertently or deliberately, thereby reducing their intended efficacy or, in the worst cases, rendering them altogether ineffective. In general, inhalers are becoming increasingly complicated with the incorporation of add-on devices, miniaturized electronics and ever more complex mechanical systems that aid aerosol delivery to the lower respiratory tract and, at the same time provide user feedback. However, these benefits often come at a significant cost, and there are signs that increasing attention will need to be given to the cost–benefit equation in the future. This review explores the development of pressurized metered-dose inhalers, dry powder inhalers and devices for liquid-droplet dispersal and inhalation from the perspective of the patient, by focusing on aspects that improve user interaction. These include designed-in features, such as breath-enhanced or breath-actuated operation that interact with the breathing pattern of the user, as well as more direct feedback aids that confirm, to the patient or healthcare provider that the dose has been delivered and that the patient has inhaled.

Aerodynamic Instability and Life-Limiting Effects of Inlet and Interstage Water Injection Into Gas Turbines

Gas turbine power enhancement technologies, such as inlet fogging, interstage water injection, saturation cooling, inlet chillers, and combustor injection, are being employed by end users without evaluating the potentially negative effects these devices may have on the operational integrity of the gas turbine. Particularly, the effect of these add-on devices, off-design operating conditions, nonstandard fuels, and compressor degradation∕fouling on the gas turbine’s axial compressor surge margin and aerodynamic stability is often overlooked. Nonetheless, compressor aerodynamic instabilities caused by these factors can be directly linked to blade high-cycle fatigue and subsequent catastrophic gas turbine failure; i.e., a careful analysis should always proceed the application of power enhancement devices, especially if the gas turbine is operated at extreme conditions, uses older internal parts that are degraded and weakened, or uses nonstandard fuels. This paper discusses a simplified method to evaluate the principal factors that affect the aerodynamic stability of a single-shaft gas turbine’s axial compressor. As an example, the method is applied to a frame-type gas turbine and results are presented. These results show that inlet cooling alone will not cause gas turbine aerodynamic instabilities, but that it can be a contributing factor if for other reasons the machine’s surge margin is already slim. The approach described herein can be employed to identify high-risk applications and bound the gas turbine operating regions to limit the risk of blade life reducing aerodynamic instability and potential catastrophic failure.

A new add-on spacer design concept for dry-powder inhalers

A new add-on spacer design concept for a commercial dry powder inhaler (Turbuhaler ®, Astra Pharma Inc., Mississauga, Ontario) is proposed here. Design partial optimization is performed using computational fluid dynamics. The performance of a simplified straight diffuser and a partially optimized geometry are evaluated by measuring the impact of these add-on devices on efficiencies of aerosol deposition in an idealized mouth–throat cast. HPLC and UV spectroscopy techniques are used in the aerosol deposition measurements. Turbuhaler ® (terbutaline sulfate, 500 μg ) aerosol and an inhalation flow rate of 70 l/ min are used for both simplified and partially optimized add-on devices. In addition, monodisperse aerosols for three inertial parameter values, ρ p d p 2Q( g μm 2 s −1 ), of 6635, 14,700 and 23,430 are used for the partially optimized geometry. Compared to Turbuhaler ® alone, the newly developed and partially optimized spacer significantly improved total aerosol delivery distal to the mouth–throat cast by approximately 47% for Turbuhaler ® aerosol and 17%, 27% and 107%, respectively, for the above monodisperse aerosols. In contrast, the straight diffuser did not significantly improve delivery distal to the mouth–throat replica.

Canadian Standards Association Standard CAN/CSA/Z264.1-02:2002: A New Voluntary Standard for Spacers and Holding Chambers Used with Pressurized Metered-Dose Inhalers

A new Canadian standard (CAN/CSA/Z264.1-02:2002) has been published with the purpose of helping to ensure the safety, efficacy and functionality of spacers and/or holding chambers. They are prescribed for use by spontaneously breathing patients for the treatment of various respiratory diseases where medication is delivered to the lungs using pressurized-metered dose inhalers. This consensus standard was developed with the support of pharmaceutical companies and manufacturers of spacers and holding chambers, and with the help of clinicians, retail pharmacists and representatives of patient advocate bodies associated with respiratory diseases and the dissemination of information related to the treatment and the delivery of inhaled medications. Advice was also sought from expert groups outside of Canada to ensure that the standard would be relevant internationally. Whereas monographs in the pharmaceutical compendia and guidance documents published by regulatory bodies provide information that is largely about the drug product and inhaler, this is the only standard whose focus is primarily on these add-on devices. The purpose of the present review is to highlight the main features of the standard for clinicians by describing its scope, the tests that are intended to assure the robustness of the construction of these devices, the type of testing that is specified to establish in vitro efficacy, and the recommendations for the marking and labelling of the device and its associated packaging. Manufacturers who test their products to this Canadian Standards Association standard will be able to provide performance information about add-on devices to the clinician, facilitating an informed decision when selecting devices for patients.

Neural potentials and micro-signals of non-linear deep and shallow conical shells

Conventional sensors, such as proximeters and accelerometers, are add-on devices usually adding additional weights to structures and machines. Health monitoring of flexible structures by electroactive smart materials has been investigated over the years. Thin-film piezoelectric material, e.g. polyvinylidene fluoride (PVDF) polymeric material, is a lightweight and dynamic sensitive material appearing to be a perfect candidate in monitoring structure's dynamic state and health status of flexible shell structures with complex geometries. The complexity of shell structures has thwarted the progress in studying the distributed sensing of shell structures. Linear distributed sensing of various structures have been studied, e.g. beams, plates, cylindrical shells, conical shells, spherical shells, paraboloidal shells and toroidal shells. However, distributed microscopic neural signals of non-linear shell structures has not been carried out rigorously. This study is to evaluate microscopic signals, modal voltages and distributed micro-neural signal components of truncated non-linear conical shells laminated with distributed infinitesimal piezoelectric neurons. Signal generation of distributed neuron sensors laminated on conical shells is defined first. The dynamic neural signal of truncated non-linear conical shells consists of microscopic linear and non-linear membrane components and linear bending component based on the von Karman geometric non-linearity. Micro-signals, modal voltages and distributed neural signal components of two different truncated non-linear conical shells are investigated and their sensitivities discussed.

Cascade Impactors for the Size Characterization of Aerosols from Medical Inhalers: Their Uses and Limitations

Cascade impactors, including the multi-stage liquid impinger, are by far the most widely encountered means for the in vitro determination of the particle size distribution of aerosols from medical inhalers, both in product development, batch release and in applications with add-on devices. This is because they directly measure aerodynamic size, which is the most relevant parameter to describe particle transport within the respiratory tract. At the same time, it is possible to quantify the mass of active pharmaceutical ingredient in different size ranges independent of other non-physiologically active components of the formulation. We begin by providing an overview of the operating principles of impactors and then highlight the various configurations and adaptations that have been adopted to characterize the various classes of inhaler. We continue by examining the limitations of the cascade impaction method, in particular looking at potential sources of measurement bias and discussing both appropriate and inappropriate uses of impactor-generated data. We also present a synopsis of current developments, including the Next Generation Pharmaceutical Impactor, and automation of cascade impactors for routine inhaler performance measurements.

Selection of inherently safer process routes: a case study

Increased public concern about safety issues and stringent environmental standards has led plant designers to consider inherently safer design. The term ‘inherently safer’ implies that the process is safe by its very nature and not externally constrained to be safe by the use of add-on systems and devices. Such opportunities for developing inherently safer process are highest in the early stages of design. Constraints such as time, lack of knowledge and inadequate inherent safety analysis tools are often cited as obstacles to development and implementation of inherently safer design. In this paper, we describe an inherent safety analysis methodology that can be applied in the early stages of process development. The methodology is based on an inherent safety index for comparing process routes and heuristics for identifying hazards and generating alternative designs. This methodology has been implemented as one module in iSafe, an intelligent system that automates inherent safety analysis. One key benefit of iSafe is substantial reduction in the time and effort required to perform safety analysis. Automation of the inherent safety analysis also makes it more thorough and detailed, minimizes or eliminates human errors, facilitates documentation and makes the study results available online for detailed safety analysis and review in the later stages of process design. The details of inherent safety analysis at the route selection stage are discussed in this paper and illustrated by comparing competing processes for acetic acid manufacture.

Technology approach to aero engine noise reduction

Transportation noise is one of the most pressing environmental problems of modern societies. Aircraft noise is second only to road traffic noise in drawing complaints from the public about noise pollution. Therefore intensive research efforts are necessary on the national levels as well as the European level to reduce the noise load around airports. The most effective and economical way to reach this goal is noise reduction at the source. The aero engines of today's transport aircraft are the dominant noise sources for most flight conditions, although airframe noise does play an important role for landing aircraft. In this paper noise reduction studies for aero engines are described in which DLR are involved. The topics discussed are low noise fan design, active noise control using wall-flush loudspeakers as secondary sources, ANC using active stators as secondary sources, ANC using flow induced secondary sources at the rotor tips, reduction of low-pressure turbine noise, and flight tests for validation of add-on noise reduction devices.

Development of Energy-Absorbing Composite Utility Pole

The serious hazard presented by unforgiving timber utility poles installed along the nation’s roadways has long been recognized by the roadside safety community. However, relatively little attention has been devoted to the development of safer utility poles beyond breakaway timber pole designs. A new generation of utility pole designs that use energy-absorbing composite materials offers a solution to the development and implementation of safer utility poles that have a cost advantage over breakaway timber poles and can be tailored to achieve the desired functional performance and energy absorption characteristics inherently without the need for additional strength members or add-on energy absorption devices. This research has resulted in the development of an energy-absorbing fiberglass-reinforced composite (FRC) utility pole design that meets structural performance requirements for environmental loading in accordance with the National Electrical Safety Code for Class 4 poles and safety performance criteria in compliance with NCHRP Report 350 Test Level 2 conditions for utility poles. Developmental testing and analyses were performed to support the development of a prototype design for demonstration testing. Full-scale crash testing has demonstrated the ability of the composite pole to absorb the vehicle’s impact energy by progressive crushing and fracture propagation as the vehicle is brought to a controlled stop. In addition to offering improved safety performance, the energy-absorbing FRC pole provides significant functional advantages, such as reduced weight, an improved strength-to-weight ratio, increased longevity, ease of installation, low maintenance, and resistance to environmental degradation.

Deposition and Pharmacokinetics of Flunisolide Delivered from Pressurized Inhalers Containing Non-CFC and CFC Propellants

Our objective was to assess the deposition and pharmacokinetics of a novel formulation of flunisolide (Aerobid, Forest Laboratories) in hydrofluoroalkane (HFA) 134a delivered by pressurized metered dose inhaler (pMDI). The design was a two-way crossover investigation in 12 healthy male subjects comparing HFA-134a flunisolide by pMDI versus pMDI plus 50 mL spacer device. Four of these subjects also took part in a two-way crossover investigation comparing chlorofluorocarbon (CFC) flunisolide pMDI versus pMDI plus Aerochamber holding chamber. The imaging technique of gamma scintigraphy was used to quantify total and regional lung deposition of flunisolide. Plasma levels of flunisolide and its major metabolite (6beta-OH flunisolide) were also determined. The spacer and Aerochamber reduced oropharyngeal deposition dramatically for both the HFA and CFC products (mean 59.8 to 14.9% (p < 0.01) of ex-valve (metered) dose for HFA product; 66.3 to 12.3% (p < 0.01) of ex-valve dose for CFC product) owing to deposition of part of the dose on the walls of the add-on devices themselves. Lung deposition averaged 22.6 and 40.4% (p < 0.01) of the ex-valve dose for the HFA formulation used with pMDI alone and with pMDI plus spacer. Mean lung deposition of the CFC formulation delivered via the Aerochamber (mean 23.4%) was higher than that for the CFC pMDI alone (mean 17.0%), but this difference was not statistically significant. Lung deposition expressed as percentage ex-device (delivered) dose averaged 68.3% for HFA pMDI plus spacer and 19.7% for CFC pMDI. Plasma levels of flunisolide were higher for the pMDI plus spacer than for pMDI alone, reflecting higher lung deposition via the spacer, but plasma levels of the 6beta-OH flunisolide metabolite were higher for the pMDI alone as a consequence of higher oropharyngeal deposition. When delivered via the spacer, pulmonary targeting of the flunisolide HFA formulation was improved compared with the CFC formulation, which should benefit patients by providing satisfactory asthma therapy from a much-reduced delivered dose of flunisolide.

Effect of Different Parameters on the Drag Coefficient for Commercial Vehicles

Large commercial vehicles (e.g. truck-trailer combination), due to their function, are bluff bodies by nature. The truck-trailer combination usually gives a drag coefficient that is less than that for a trailer alone. The interference between the commercial vehicles and other small vehicles is of primary importance especially when moving in driving tunnels that are characterized by their limited space. 1/19-scale models for commercial vehicles are employed in the experimental work performed here. Three-dimensional pressure measurements are recorded for analyzing the aerodynamic behavior and calculating the drag coefficient. Add-on devices (deflectors) are used. Measurements are supported by both numerical calculations and flow visualization. Results show that add-on devices play a very important role in improving the aerodynamic characteristics of commercial vehicles.