A Point-of-Care Algorithm to Guide Proper Device Selection for Ambulatory Electrocardiography.

In the outpatient setting, ambulatory electrocardiography is the most frequently used diagnostic modality for the evaluation of patients in whom cardiac arrhythmias or conduction abnormalities are suspected. Proper selection of the device type and monitoring duration is critical for optimizing diagnostic yield and cost-effective resource utilization. However, despite guidance from major professional societies, the lack of systematic guidance for proper test selection in many institutions results in the need for repeat testing, which leads to not only increased resource utilization and cost of care, but also suboptimal patient care. To address this unmet need at our own institution, we formed a multidisciplinary panel to develop a concise, yet comprehensive algorithm, incorporating the most common indications for ambulatory electrocardiography, to efficiently guide clinicians to the most appropriate test option for a given clinical scenario, with the goal of maximizing diagnostic yield and optimizing resource utilization. The algorithm was designed as a single-page, color-coded flowchart to be utilized both as a rapid reference guide in printed form, and a decision support tool embedded within the electronic medical records system at the point of order entry. We believe that systematic adoption of this algorithm will optimize diagnostic efficiency, resource utilization, and importantly, patient care and satisfaction.

Modeling inorganic aerosols and their response to changes in precursor concentration in Mexico City.

Based on data from the 1997 Investigación sobre Materia Particulada y Deterioro Atmosférico-Aerosol and Visibility Evaluation Research (IMADA-EVER) campaign and the inorganic aerosol model ISORROPIA, the response of inorganic aerosols to changes in precursor concentrations was calculated. The aerosol behavior is dominated by the abundance of ammonia and thus, changes in ammonia concentration are expected to have a small effect on particle concentrations. Changes in sulfate and nitrate are expected to lead to proportional reductions in inorganic fine particulate matter (PM2.5). Comparing the predictions of ISORROPIA with the observations, the lowest bias and error are achieved when the aerosols are assumed to be in the efflorescence branch. Including crustal species reduces the bias and error for nitrate but does not improve overall model performance. The estimated response of inorganic PM2.5 to changes in precursor concentrations is affected by the inclusion of crustal species in some cases, although average responses are comparable with and without crustal species. Observed concentrations of particle chloride suggest that gas phase concentrations of hydrogen chloride may not be negligible, and future measurement campaigns should include observations to test this hypothesis. Our ability to model aerosol behavior in Mexico City and, thus, design control strategies, is constrained primarily by a lack of observations of gas phase precursors. Future campaigns should focus in particular on better understanding the temporal and spatial distribution of ammonia concentrations. In addition, gas phase observations of nitric acid are needed, and a measure of particle water content will allow stable versus metastable aerosol behavior to be distinguished.

Co-control of urban air pollutants and greenhouse gases in Mexico City.

This study addresses the synergies of mitigation measures to control urban air pollutant and greenhouse gas (GHG) emissions, in developing integrated "co-control" strategies for Mexico City. First, existing studies of emissions reduction measures--PROAIRE (the air quality plan for Mexico City) and separate GHG studies--are used to construct a harmonized database of options. Second, linear programming (LP) is developed and applied as a decision-support tool to analyze least-cost strategies for meeting co-control targets for multiple pollutants. We estimate that implementing PROAIRE measures as planned will reduce 3.1% of the 2010 metropolitan CO2 emissions, in addition to substantial local air pollutant reductions. Applying the LP, PROAIRE emissions reductions can be met at a 20% lower cost, using only the PROAIRE measures, by adjusting investments toward the more cost-effective measures; lower net costs are possible by including cost-saving GHG mitigation measures, but with increased investment. When CO2 emission reduction targets are added to PROAIRE targets, the most cost-effective solutions use PROAIRE measures for the majority of local pollutant reductions, and GHG measures for additional CO2 control. Because of synergies, the integrated planning of urban-global co-control can be beneficial, but we estimate that for Mexico City these benefits are often small.