A Comparative Life Cycle Assessment between a Metered Dose Inhaler and Electric Nebulizer

Life cycle assessment (LCA) evaluates the environmental impact of a product based on the materials and processes used to manufacture the item as well as the item’s use and disposal. The objective of this LCA was to evaluate and compare the environmental impact of a metered dose inhaler, specifically the Proventil® HFA inhaler (Merk & Co., Inc., Kenilworth, NJ, USA), and an electric nebulizer, specifically the DeVilbiss Pulmo-Aide® nebulizer (DeVilbiss, Port Washington, NY, USA). GaBi LCA software was used to model the global warming potential (GWP) of each product by using substantiated data and well-justified assumptions for the components, manufacturing, assembly, and use of both devices. The functional unit used to model each device was one dose of the active drug, albuterol sulfate. The inhaler’s GWP, 0.0972 kg CO2-eq, was greater than the nebulizer’s even when uncertain parameters were varied ±100x. During the use phase ofa the inhaler, which accounted for approximately 96% of the inhaler’s total GWP, HFA 134a is used as a propellant to deliver the drug. The total GWP for the electric nebulizer was 0.0294 kg CO2-eq assuming that the mouthpiece was cleaned in a dishwasher, while it was 0.0477 kg CO2-eq when the nebulizer mouthpiece was hand washed between uses. The GWP breakeven scenario between dishwashing and hand washing occurred when the mouthpiece accounted for 10% of the dishwasher load

Characterization of a Human Powered Nebulizer Compressor for Resource Poor Settings

Background Respiratory disease accounts for three of the ten leading causes of death worldwide. Many of these diseases can be treated and diagnosed using a nebulizer. Nebulizers can also be used to safely and efficiently deliver vaccines. Unfortunately, commercially available nebulizers are not designed for use in regions of the world where lung disease is most prevalent: they are electricity-dependent, cost-prohibitive, and not built to be reliable in harsh operating conditions or under frequent use. To overcome these limitations, the Human Powered Nebulizer compressor (HPN) was developed. The HPN does not require electricity; instead airflow is generated manually through a hand-crank or bicycle-style pedal system. A health care worker or other trained individual operates the device while the patient receives treatment. This study demonstrates functional specifications of the HPN in comparison with a standard commercially available electric jet nebulizer compressor, the DeVilbiss Pulmo-Aide 5650D (Pulmo-Aide). Methods Pressure and flow characteristics were measured with a rotameter and pressure transducer, respectively. Volume nebulized by each compressor was determined by mass, and particle size distribution was determined via laser diffraction. The Hudson RCI Micro Mist nebulizer mouthpiece was used with both compressors. Results The pressure and flow generated by the HPN and Pulmo-Aide were: 15.17 psi and 10.5 L/min; and 14.65 psi and 11.2 L/min, respectively. The volume of liquid delivered by each was equivalent, 1.097 ± 0.107 mL (mean ± s.e.m., n = 13) for the HPN and 1.092 ± 0.116 mL for the Pulmo-Aide. The average particle size was also equivalent, 5.38 ± 0.040 micrometers (mean ± s.e.m., n = 7) and 5.40 ± 0.025 micrometers, respectively. Conclusions Based on these characteristics, the HPN’s performance is equivalent to a popular commercially available electric nebulizer compressor. The findings presented in this paper, combined with the results of two published clinical studies, suggest that the HPN could serve as an important diagnostic and therapeutic tool in the fight against global respiratory health challenges including: tuberculosis, chronic obstructive pulmonary disease, asthma, and lower respiratory infections

Microfocal X-Ray Computed Tomography Post-Processing Operations for Optimizing Reconstruction Volumes of Stented Arteries During 3D Computational Fluid Dynamics Modeling

Restenosis caused by neointimal hyperplasia (NH) remains an important clinical problem after stent implantation. Restenosis varies with stent geometry, and idealized computational fluid dynamics (CFD) models have indicated that geometric properties of the implanted stent may differentially influence NH. However, 3D studies capturing the in vivo flow domain within stented vessels have not been conducted at a resolution sufficient to detect subtle alterations in vascular geometry caused by the stent and the subsequent temporal development of NH. We present the details and limitations of a series of post-processing operations used in conjunction with microfocal X-ray CT imaging and reconstruction to generate geometrically accurate flow domains within the localized region of a stent several weeks after implantation. Microfocal X-ray CT reconstruction volumes were subjected to an automated program to perform arterial thresholding, spatial orientation, and surface smoothing of stented and unstented rabbit iliac arteries several weeks after antegrade implantation. A transfer function was obtained for the current post-processing methodology containing reconstructed 16 mm stents implanted into rabbit iliac arteries for up to 21 days after implantation and resolved at circumferential and axial resolutions of 32 and 50 μm, respectively. The results indicate that the techniques presented are sufficient to resolve distributions of WSS with 80% accuracy in segments containing 16 surface perturbations over a 16 mm stented region. These methods will be used to test the hypothesis that reductions in normalized wall shear stress (WSS) and increases in the spatial disparity of WSS immediately after stent implantation may spatially correlate with the temporal development of NH within the stented region

Antegrade Iliac Artery Stent Implantation for the Temporal and Spatial Examination of Stent-Induced Neointimal Hyperplasia and Alterations in Regional Fluid Dynamics

Neointimal hyperplasia remains an important problem after stent implantation. Previous investigations examining vascular responses to stent implantation and effects of drugs have used a retrograde deployment approach that may inadvertently alter the local fluid dynamics surrounding the stent. We present a model of antegrade iliac artery stent implantation that facilitates the analysis of stent-induced alterations in neointimal hyperplasia and wall shear stress in vivo.Methods: Stent delivery catheters were inserted through the left carotid artery in anesthetized rabbits (n=37). Catheters were advanced under fluoroscopic guidance to the distal iliac arteries, where the stent was deployed. Hemotoxylin and eosin (H&E) staining of unstented and stented vascular sections was performed 21 days after implantation. Results: Selective unilateral stent implantation was successful in 32 of 37 rabbits. No histological abnormalities were observed in the aorta, contralateral unstented iliac, or distal femoral arteries. Neointimal hyperplasia was localized to the stented region.Discussion: The model of stent implantation was relatively easy to perform and produced selective neointimal hyperplasia within the stented region without evidence of damage, cellular proliferation, or flow disruption in the surrounding normal arterial vessels. The model will allow detailed examination of the influence of stent implantation on indices of wall shear stress, neointimal hyperplasia, the mechanisms of cellular proliferation in vivo, and their modification by drugs

Circumferential Vascular Deformation after Stent Implantation Alters Wall Shear Stress Evaluated with Time-Dependent 3D Computational Fluid Dynamics Models

The success of vascular stents in the restoration of blood flow is limited by restenosis. Recent data generated from computational fluid dynamics (CFD) models suggest that stent geometry may cause local alterations in wall shear stress (WSS) that have been associated with neointimal hyperplasia and subsequent restenosis. However, previous CFD studies have ignored histological evidence of vascular straightening between circumferential stent struts. We tested the hypothesis that consideration of stent-induced vascular deformation may more accurately predict alterations in indexes of WSS that may subsequently account for histological findings after stenting. We further tested the hypothesis that the severity of these alterations in WSS varies with the degree of vascular deformation after implantation. Steady-state and time-dependent simulations of three-dimensional CFD arteries based on canine coronary artery measurements of diameter and blood flow were conducted, and WSS and WSS gradients were calculated. Circumferential straightening introduced areas of high WSS between stent struts that were absent in stented vessels of circular cross section. The area of vessel exposed to low WSS was dependent on the degree of circumferential vascular deformation and axial location within the stent. Stents with four vs. eight struts increased the intrastrut area of low WSS in vessels, regardless of cross-sectional geometry. Elevated WSS gradients were also observed between struts in vessels with polygonal cross sections. The results obtained using three-dimensional CFD models suggest that changes in vascular geometry after stent implantation are important determinants of WSS distributions that may be associated with subsequent neointimal hyperplasia

Treatment of Asthma Exacerbations with the Human-Powered Nebuliser: A Randomised Parallel-Group Clinical Trial

Aims: The aim of this study was to compare a low-cost, human-powered nebuliser compressor with an electric nebuliser compressor for the treatment of mild to moderate asthma exacerbations in adults and children. Methods: This was a non-blinded, parallel-group, equivalence study, with 110 subjects between 6 and 65 years of age, conducted in the emergency department of a district hospital in Ilopango, El Salvador. Participants were assigned by random allocation to receive a 2.5-mg dose of salbutamol from the experimental human-powered nebuliser or the electric nebuliser control. All assigned participants completed treatment and were included in analysis. The study was not blinded as this was clinically unfeasible; however, data analysis was blinded. Results: The mean improvement in peak flow of the experimental and control groups was 37.5 (95% confidence interval (CI) 26.7–48.2) l/min and 38.7 (95% CI, 26.1–51.3) l/min, respectively, with a mean difference of 1.3 (95% CI, −15.1 to 17.7) l/min. The mean improvement in percent-expected peak flow for the experimental and control groups was 12.3% (95% CI, 9.1–15.5%) and 13.8% (95% CI, 9.8–17.9%), respectively, with a mean difference of 1.5% (95% CI, −3.6 to 6.6%). Conclusions: The human-powered nebuliser compressor is equivalent to a standard nebuliser compressor for the treatment of mild-to-moderate asthma. (Funded by the Opus Dean’s Fund, Marquette University College of Engineering; ClinicalTrials.gov NCT01795742.

Stent Design Properties and Deployment Ratio Influence Indexes of Wall Shear Stress: a Three-Dimensional Computational Fluid Dynamics Investigation within a Normal Artery

Restenosis limits the effectiveness of stents, but the mechanisms responsible for this phenomenon remain incompletely described. Stent geometry and expansion during deployment produce alterations in vascular anatomy that may adversely affect wall shear stress (WSS) and correlate with neointimal hyperplasia. These considerations have been neglected in previous computational fluid dynamics models of stent hemodynamics. Thus we tested the hypothesis that deployment diameter and stent strut properties (e.g., number, width, and thickness) influence indexes of WSS predicted with three-dimensional computational fluid dynamics. Simulations were based on canine coronary artery diameter measurements. Stent-to-artery ratios of 1.1 or 1.2:1 were modeled, and computational vessels containing four or eight struts of two widths (0.197 or 0.329 mm) and two thicknesses (0.096 or 0.056 mm) subjected to an inlet velocity of 0.105 m/s were examined. WSS and spatial WSS gradients were calculated and expressed as a percentage of the stent and vessel area. Reducing strut thickness caused regions subjected to low WSS (/cm2) to decrease by ∼87%. Increasing the number of struts produced a 2.75-fold increase in exposure to low WSS. Reducing strut width also caused a modest increase in the area of the vessel experiencing low WSS. Use of a 1.2:1 deployment ratio increased exposure to low WSS by 12-fold compared with stents implanted in a 1.1:1 stent-to-vessel ratio. Thinner struts caused a modest reduction in the area of the vessel subjected to elevated WSS gradients, but values were similar for the other simulations. The results suggest that stent designs that reduce strut number and thickness are less likely to subject the vessel to distributions of WSS associated with neointimal hyperplasia

Reactive Oxygen Species Modulate Coronary Wall Shear Stress and Endothelial Function During Hyperglycemia

Hyperglycemia is associated with generation of reactive oxygen species (ROS), and this action may contribute to accelerated atherogenesis. We tested the hypothesis that hyperglycemia produces alterations in left anterior descending coronary artery (LAD) wall shear stress concomitant with endothelial dysfunction and ROS production in dogs (n = 12) instrumented for measurement of LAD blood flow, velocity, and diameter. Dogs were randomly assigned to receive vehicle (0.9% saline) or the superoxide dismutase mimetic 4- hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (tempol) and were administered intravenous infusions of d-glucose to achieve target blood glucose concentrations of 350 and 600 mg/dl (moderate and severe hyperglycemia, respectively). Endothelial function and ROS generation were assessed by coronary blood flow responses to acetylcholine (10, 30, and 100 ng/kg) and dihydroethidium fluorescence of myocardial biopsies, respectively. Indexes of wall shear stress were calculated with conventional fluid dynamics theory. Hyperglycemia produced dose-related endothelial dysfunction, increases in ROS production, and reductions in oscillatory shear stress that were normalized by tempol. The results suggest a direct association between hyperglycemia-induced ROS production, endothelial dysfunction, and decreases in oscillatory shear stress in vivo

Effects of a Government-Academic Partnership: Has the NSF-Census Bureau Research Network Helped Improve the U.S. Statistical System?

The National Science Foundation-Census Bureau Research Network (NCRN) was established in 2011 to create interdisciplinary research nodes on methodological questions of interest and significance to the broader research community and to the Federal Statistical System (FSS), particularly to the Census Bureau. The activities to date have covered both fundamental and applied statistical research and have focused at least in part on the training of current and future generations of researchers in skills of relevance to surveys and alternative measurement of economic units, households, and persons. This article focuses on some of the key research findings of the eight nodes, organized into six topics: (1) improving census and survey data-quality and data collection methods; (2) using alternative sources of data; (3) protecting privacy and confidentiality by improving disclosure avoidance; (4) using spatial and spatio-temporal statistical modeling to improve estimates; (5) assessing data cost and data-quality tradeoffs; and (6) combining information from multiple sources. The article concludes with an evaluation of the ability of the FSS to apply the NCRN’s research outcomes, suggests some next steps, and discusses the implications of this research-network model for future federal government research initiatives

Household food security is associated with infant feeding practices in rural Bangladesh.

Although household food security (HHFS) has been shown to affect diet, nutrition, and health of adults and also learning in children, no study has examined associations with infant feeding practices (IFP). We studied 1343 infants born between May 2002 and December 2003 in the Maternal and Infant Nutrition Intervention in Matlab study to investigate the effect of HHFS on IFP in rural Bangladesh. We measured HHFS using a previously developed 11-item scale. Cumulative and current infant feeding scales were created from monthly infant feeding data for the age groups of 1-3, 1-6, 1-9, and 1-12 mo based on comparison to infant feeding recommendations. We used lagged, dynamic, and difference longitudinal regression models adjusting for various infant and maternal variables to examine the association between HHFS and changes in IFP, and Cox proportional hazards models to examine the influence of HHFS on the duration of breast-feeding and the time of introduction of complementary foods. Better HHFS status was associated with poor IFP during 3-6 mo but was associated with better IFP during 6-9 and 9-12 mo of age. Although better HHFS was not associated with the time of introduction of complementary foods, it was associated with the type of complementary foods given to the infants. Intervention programs to support proper IFP should target mothers in food-secure households when their babies are 3-6 mo old and also mothers in food-insecure households during the 2nd half of infancy. Our results provide strong evidence that HHFS influences IFP in rural Bangladesh