Abstract TMP70: Simulation Modeling Predicts Actual Patient Transport Rates Following the Implementation of a Prehospital Comprehensive Stroke Center Direct Transport Protocol

Stroke ◽  
2020 ◽  
Vol 51 (Suppl_1) ◽  
Author(s):  
Christopher T Richards ◽  
Jane L Holl ◽  
Rebeca Khorzad ◽  
Shyam Prabhakaran
Keyword(s):  
Mathematical Model ◽  
Simulation Modeling ◽  
Systems Of Care ◽  
Discrete Event ◽  
System Level ◽  
Transport Protocol ◽  
Vessel Occlusion ◽  
Protocol Implementation ◽  
Suspected Stroke ◽  
The Impact

Introduction: Implementing emergency medical services (EMS) protocols that incorporate severe stroke screening and direct transport to comprehensive stroke centers (CSCs) has been advocated as a strategy to improve timely stroke care for patients with large vessel occlusion and hemorrhage, but such screening can have important unintended effects on stroke systems of care. Mathematical modeling can estimate the impact of prehospital CSC direct transport protocols, but few models have been evaluated after protocol implementation. Hypothesis: The proportion of patients transported to CSCs versus primary stroke centers (PSCs) in a mathematical model will approximate actual transport rates following implementation of a prehospital CSC direct transport protocol. Methods: A previously reported discrete event data simulation was used to model the proportion of patients with suspected stroke transported directly to CSCs in a large, urban EMS system with 8 CSCs, 24 PSCs, and a single municipal fire-based EMS agency responding to all 9-1-1 calls prior to implementation of a prehospital CSC direct transport protocol in late 2018. Electronic patient care records in which paramedics documented “suspected stroke” were included for analysis. The proportion of patients transported to CSCs versus PSCs in the 3 months (92 days) prior to and following protocol implementation were compared using Fisher’s exact test in Stata 12.1 (College Station, TX). Results: The simulation predicted that the proportion of patients transported to CSCs would increase by 8.3% following implementation of a prehospital CSC direct transport protocol. In the 3 months prior to protocol implementation, 247 of 872 (28.3%) suspected stroke patients were transported to CSCs, and 265 of 701 (37.8%) were transported to CSCs in the 3 months following implementation, a difference of 9.5% (p<0.001). The model underestimated the proportion of patients transported to CSCs by 1.2%. Conclusions: A mathematical model simulating the proportion of patients transported to CSCs differed by only 1.2% compared to actual rates after implementation of a prehospital CSC direct transport protocol. Simulation modeling holds promise for estimating system-level effects prior to EMS protocol implementation.

scholarly journals Epidemiological Surveillance of the Impact of the COVID-19 Pandemic on Stroke Care Using Artificial Intelligence

Stroke ◽  
2021 ◽  
Author(s):  
Raul G. Nogueira ◽  
Jason M. Davies ◽  
Rishi Gupta ◽  
Ameer E. Hassan ◽  
Thomas Devlin ◽  
...  
Keyword(s):  
Artificial Intelligence ◽  
Acute Stroke ◽  
Systems Of Care ◽  
Ct Perfusion ◽  
Stroke Care ◽  
Large Vessel ◽  
Large Vessel Occlusion ◽  
Vessel Occlusion ◽  
Number Of Patients ◽  
The Impact

Background and Purpose: The degree to which the coronavirus disease 2019 (COVID-19) pandemic has affected systems of care, in particular, those for time-sensitive conditions such as stroke, remains poorly quantified. We sought to evaluate the impact of COVID-19 in the overall screening for acute stroke utilizing a commercial clinical artificial intelligence platform. Methods: Data were derived from the Viz Platform, an artificial intelligence application designed to optimize the workflow of patients with acute stroke. Neuroimaging data on suspected patients with stroke across 97 hospitals in 20 US states were collected in real time and retrospectively analyzed with the number of patients undergoing imaging screening serving as a surrogate for the amount of stroke care. The main outcome measures were the number of computed tomography (CT) angiography, CT perfusion, large vessel occlusions (defined according to the automated software detection), and severe strokes on CT perfusion (defined as those with hypoperfusion volumes >70 mL) normalized as number of patients per day per hospital. Data from the prepandemic (November 4, 2019 to February 29, 2020) and pandemic (March 1 to May 10, 2020) periods were compared at national and state levels. Correlations were made between the inter-period changes in imaging screening, stroke hospitalizations, and thrombectomy procedures using state-specific sampling. Results: A total of 23 223 patients were included. The incidence of large vessel occlusion on CT angiography and severe strokes on CT perfusion were 11.2% (n=2602) and 14.7% (n=1229/8328), respectively. There were significant declines in the overall number of CT angiographies (−22.8%; 1.39–1.07 patients/day per hospital, P <0.001) and CT perfusion (−26.1%; 0.50–0.37 patients/day per hospital, P <0.001) as well as in the incidence of large vessel occlusion (−17.1%; 0.15–0.13 patients/day per hospital, P <0.001) and severe strokes on CT perfusion (−16.7%; 0.12–0.10 patients/day per hospital, P <0.005). The sampled cohort showed similar declines in the rates of large vessel occlusions versus thrombectomy (18.8% versus 19.5%, P =0.9) and comprehensive stroke center hospitalizations (18.8% versus 11.0%, P =0.4). Conclusions: A significant decline in stroke imaging screening has occurred during the COVID-19 pandemic. This analysis underscores the broader application of artificial intelligence neuroimaging platforms for the real-time monitoring of stroke systems of care.

scholarly journals Simulation Modeling of Competitive Strategy of Pricing

2019 ◽  
Vol 20 (2) ◽  
pp. 294-321
Author(s):  
Sergey Sorokin ◽  
Irina Varpaeva ◽  
Ol'ga Grishina
Keyword(s):  
Mathematical Model ◽  
Simulation Modeling ◽  
Computational Experiment ◽  
Initial Conditions ◽  
Market Price ◽  
Local Market ◽  
Commercial Activities ◽  
Relationship Model ◽  
The Impact ◽  
Aging Factor

Efficiency of commercial activities depends on many factors. One of the tools to study their influence is mathematical modeling. The goal of the study is to conduct a computational experiment that simulates the dynamics of the supplier’s sales volumes in a competitive environment under various initial conditions. We take into account the possibility of changing the price of products (goods), depending on changes in sales volumes. The limitation of the experiment is the conditions of the local market and the presence of the maximum value of purchasing power within it. To conduct an experiment, it is necessary to solve the following tasks: to find out the impact of sales volumes changes caused by competition on changes of the price of products (and the price of products must be calculated according to product aging factor); to consider consumers’ preferences, on which “consumer-supplier” relationships are based and to determine the relationship between the pricing models and the model of competing relations of the “supplier-suppliers” type. To achieve this goal, we employed heuristic methods of simulation modeling and the analogy method (universality). Based on simulation modeling and the method of analogies (universality), we developed a mathematical model as a part of a computational experiment. The former simulates the market price of a product and the dynamics of sales volumes of a supplier, which considers correlation between the market price for products (goods) and their aging factor, as well as consumers’ preferences and pricing model and competing relationship model. The application of the mathematical model developed by the authors allows to take into account many interrelated factors that influence the sales dynamics of market participants in real economic situations.

Abstract WP334: Stroke Case Volume After Implementation of the 24 Hour Extended Intra-Arterial Thrombectomy Window

Stroke ◽  
2020 ◽  
Vol 51 (Suppl_1) ◽  
Author(s):  
Jessica Glenn ◽  
Sharon Heaton ◽  
Ciarán Powers ◽  
Shahid Nimjee ◽  
Patrick Youssef ◽  
...  
Keyword(s):  
Systems Of Care ◽  
Ct Perfusion ◽  
Stroke Patients ◽  
Case Volume ◽  
Anterior Circulation ◽  
Vessel Occlusion ◽  
Number Of Patients ◽  
Comprehensive Stroke Center ◽  
The Impact ◽  
Treatment Window

Introduction: The results of the DAWN and DEFUSE 3 trials demonstrated improved functional outcome with mechanical thrombectomy (MT) in stroke patients who present with anterior circulation large vessel occlusion (LVO) up to a 24 hours after last known well. The AHA guidelines were updated to include this recommendation in 2018, but the impact of the increase in number of patients treated in clinical practice remains unknown. Methods: We reviewed ischemic stroke MT patients admitted to a comprehensive stroke center (DEFUSE 3 trial participating site), from July 2015- July 2019. Our center instituted a 24 hour IAT window protocol in March 2018 (Figure 1). Eligibility for MT in the 24 hour window followed the DEFUSE 3 criteria including the presence of LVO, National Institute of Health Stroke Scale (NIHSS) > 6, and favorable CT perfusion imaging. Results: During this 4-year period, 290 stroke patients with LVO received MT at our institution. MT volumes increased in each subsequent year in this study as follows: July 2015 (44), July 2016 (58), July 2017 (73) and July 2018 (115). An increase in MT volume was observed after the expansion of the treatment window to 24 hours (Figure 2). In the period prior to the expanded 24 hour treatment window, MT volumes were 25-33 per 6 month period. After the 24 hour treatment window was started, MT volumes were 58-60 per 6 month period. Conclusions: Expanding the MT window to 24 hours has nearly doubled the MT case volume at our single center. This dramatic increase in IAT clinical utilization observed with expansion to the 24 hour window has implications for systems of care and resource optimization of the stroke patient.

The Impact of Light Polarisation on Light Field of Scenes with Multiple Reflections

2020 ◽  
pp. 108-115 ◽  
Author(s):  
Vladimir P. Budak ◽  
Anton V. Grimaylo
Keyword(s):  
Mathematical Model ◽  
Light Field ◽  
Global Illumination ◽  
Multiple Reflections ◽  
Software Environment ◽  
The Monte Carlo Method ◽  
Mueller Matrices ◽  
Volume Integration ◽  
The Impact

The article describes the role of polarisation in calculation of multiple reflections. A mathematical model of multiple reflections based on the Stokes vector for beam description and Mueller matrices for description of surface properties is presented. On the basis of this model, the global illumination equation is generalised for the polarisation case and is resolved into volume integration. This allows us to obtain an expression for the Monte Carlo method local estimates and to use them for evaluation of light distribution in the scene with consideration of polarisation. The obtained mathematical model was implemented in the software environment using the example of a scene with its surfaces having both diffuse and regular components of reflection. The results presented in the article show that the calculation difference may reach 30 % when polarisation is taken into consideration as compared to standard modelling.

Comparative assessment of morphological mechanisms of maintaining structural liver homeostasis in the dynamics of exposure to coal-rock dust and sodium fluoride on the body

2020 ◽  
pp. 189-194
Author(s):  
M. S. Bugaeva ◽  
O. I. Bondarev ◽  
N. N. Mikhailova ◽  
L. G. Gorokhova
Keyword(s):  
Sodium Fluoride ◽  
Morphological Changes ◽  
The Body ◽  
System Level ◽  
Production Factor ◽  
Coal Rock ◽  
The Impact ◽  
Structural Homeostasis ◽  
Rock Dust

Introduction. The impact on the body of such factors of the production environment as coal-rock dust and fluorine compounds leads to certain shift s in strict indicators of homeostasis at the system level. Maintaining the relative constancy of the internal environment of the body is provided by the functional consistency of all organs and systems, the leading of which is the liver. Organ repair plays a crucial role in restoring the structure of genetic material and maintaining normal cell viability. When this mechanism is damaged, the compensatory capabilities of the organ are disrupted, homeostasis is disrupted at the cellular and organizational levels, and the development of the main pathological processes is noted.The aim of the study is to compare the morphological mechanisms of maintaining structural homeostasis of the liver in the dynamics of the impact on the body of coal-rock dust and sodium fluoride.Materials and methods. Experimental studies were conducted on adult white male laboratory rats. Features of morphological mechanisms for maintaining structural homeostasis of the liver in the dynamics of exposure to coal-rock dust and sodium fluoride were studied on experimental models of pneumoconiosis and fluoride intoxication. For histological examination in experimental animals, liver sampling was performed after 1, 3, 6, 9, 12 weeks of the experiment.Results. The specificity of morphological changes in the liver depending on the harmful production factor was revealed. It is shown that chronic exposure to coal-rock dust and sodium fluoride is characterized by the development of similar morphological changes in the liver and its vessels from the predominance of the initial compensatory-adaptive to pronounced violations of the stromal and parenchymal components. Long-term inhalation of coal-rock dust at 1–3 weeks of seeding triggers adaptive mechanisms in the liver in the form of increased functional activity of cells, formation of double-core hepatocytes, activation of immunocompetent cells and endotheliocytes, ensuring the preservation of the parenchyma and the general morphostructure of the organ until the 12th week of the experiment. Exposure to sodium fluoride leads to early disruption of liver compensatory mechanisms and the development of dystrophic changes in the parenchyma with the formation of necrosis foci as early as the 6th week of the experiment.Conclusions. The study of mechanisms for compensating the liver structure in conditions of long-term exposure to coal-rock dust and sodium fluoride, as well as processes that indicate their failure, and the timing of their occurrence, is of theoretical and practical importance for developing recommendations for the timely prevention and correction of pathological conditions developing in employees of the aluminum and coal industry.The authors declare no conflict of interests.

Analyzing the Impact of Healthy Behavior on Weight Change with a Provable Mathematical Model (Preprint)

2020 ◽  
Author(s):  
Ayan Chatterjee ◽  
Ram Bajpai ◽  
Pankaj Khatiwada
Keyword(s):  
Physical Activity ◽  
Mathematical Model ◽  
Health Behavior ◽  
Weight Change ◽  
Simulated Data ◽  
Negative Behavior ◽  
Healthy Behavior ◽  
Healthy Habits ◽  
Lifestyle Diseases ◽  
The Impact

BACKGROUND Lifestyle diseases are the primary cause of death worldwide. The gradual growth of negative behavior in humans due to physical inactivity, unhealthy habit, and improper nutrition expedites lifestyle diseases. In this study, we develop a mathematical model to analyze the impact of regular physical activity, healthy habits, and a proper diet on weight change, targeting obesity as a case study. Followed by, we design an algorithm for the verification of the proposed mathematical model with simulated data of artificial participants. OBJECTIVE This study intends to analyze the effect of healthy behavior (physical activity, healthy habits, and proper dietary pattern) on weight change with a proposed mathematical model and its verification with an algorithm where personalized habits are designed to change dynamically based on the rule. METHODS We developed a weight-change mathematical model as a function of activity, habit, and nutrition with the first law of thermodynamics, basal metabolic rate (BMR), total daily energy expenditure (TDEE), and body-mass-index (BMI) to establish a relationship between health behavior and weight change. Followed by, we verified the model with simulated data. RESULTS The proposed provable mathematical model showed a strong relationship between health behavior and weight change. We verified the mathematical model with the proposed algorithm using simulated data following the necessary constraints. The adoption of BMR and TDEE calculation following Harris-Benedict’s equation has increased the model's accuracy under defined settings. CONCLUSIONS This study helped us understand the impact of healthy behavior on obesity and overweight with numeric implications and the importance of adopting a healthy lifestyle abstaining from negative behavior change.

scholarly journals Nanofluid flow containing carbon nanotubes with quartic autocatalytic chemical reaction and Thompson and Troian slip at the boundary

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Muhammad Ramzan ◽  
Jae Dong Chung ◽  
Seifedine Kadry ◽  
Yu-Ming Chu ◽  
Muhammad Akhtar
Keyword(s):  
Mathematical Model ◽  
Carbon Nanotubes ◽  
Drag Force ◽  
Chemical Reaction ◽  
Slip Velocity ◽  
Volume Fraction ◽  
Surface Drag ◽  
Nanofluid Flow ◽  
Velocity Parameter ◽  
The Impact

Abstract A mathematical model is envisioned to discourse the impact of Thompson and Troian slip boundary in the carbon nanotubes suspended nanofluid flow near a stagnation point along an expanding/contracting surface. The water is considered as a base fluid and both types of carbon nanotubes i.e., single-wall (SWCNTs) and multi-wall (MWCNTs) are considered. The flow is taken in a Dacry-Forchheimer porous media amalgamated with quartic autocatalysis chemical reaction. Additional impacts added to the novelty of the mathematical model are the heat generation/absorption and buoyancy effect. The dimensionless variables led the envisaged mathematical model to a physical problem. The numerical solution is then found by engaging MATLAB built-in bvp4c function for non-dimensional velocity, temperature, and homogeneous-heterogeneous reactions. The validation of the proposed mathematical model is ascertained by comparing it with a published article in limiting case. An excellent consensus is accomplished in this regard. The behavior of numerous dimensionless flow variables including solid volume fraction, inertia coefficient, velocity ratio parameter, porosity parameter, slip velocity parameter, magnetic parameter, Schmidt number, and strength of homogeneous/heterogeneous reaction parameters are portrayed via graphical illustrations. Computational iterations for surface drag force are tabulated to analyze the impacts at the stretched surface. It is witnessed that the slip velocity parameter enhances the fluid stream velocity and diminishes the surface drag force. Furthermore, the concentration of the nanofluid flow is augmented for higher estimates of quartic autocatalysis chemical.

scholarly journals Bottlenecks in the Acute Stroke Care System during the COVID-19 Pandemic in Catalonia

2021 ◽  
pp. 1-9
Author(s):  
Anna Ramos-Pachón ◽  
Álvaro García-Tornel ◽  
Mònica Millán ◽  
Marc Ribó ◽  
Sergi Amaro ◽  
...  
Keyword(s):  
Acute Stroke ◽  
Functional Outcome ◽  
Stroke Care ◽  
Care Quality ◽  
Point Of View ◽  
Stroke Severity ◽  
Acute Stroke Care ◽  
Vessel Occlusion ◽  
Prehospital Delays ◽  
The Impact

<b><i>Introduction:</i></b> The COVID-19 pandemic resulted in significant healthcare reorganizations, potentially striking standard medical care. We investigated the impact of the COVID-19 pandemic on acute stroke care quality and clinical outcomes to detect healthcare system’s bottlenecks from a territorial point of view. <b><i>Methods:</i></b> Crossed-data analysis between a prospective nation-based mandatory registry of acute stroke, Emergency Medical System (EMS) records, and daily incidence of COVID-19 in Catalonia (Spain). We included all stroke code activations during the pandemic (March 15–May 2, 2020) and an immediate prepandemic period (January 26–March 14, 2020). Primary outcomes were stroke code activations and reperfusion therapies in both periods. Secondary outcomes included clinical characteristics, workflow metrics, differences across types of stroke centers, correlation analysis between weekly EMS alerts, COVID-19 cases, and workflow metrics, and impact on mortality and clinical outcome at 90 days. <b><i>Results:</i></b> Stroke code activations decreased by 22% and reperfusion therapies dropped by 29% during the pandemic period, with no differences in age, stroke severity, or large vessel occlusion. Calls to EMS were handled 42 min later, and time from onset to hospital arrival increased by 53 min, with significant correlations between weekly COVID-19 cases and more EMS calls (rho = 0.81), less stroke code activations (rho = −0.37), and longer prehospital delays (rho = 0.25). Telestroke centers were afflicted with higher reductions in stroke code activations, reperfusion treatments, referrals to endovascular centers, and increased delays to thrombolytics. The independent odds of death increased (OR 1.6 [1.05–2.4], <i>p</i> 0.03) and good functional outcome decreased (mRS ≤2 at 90 days: OR 0.6 [0.4–0.9], <i>p</i> 0.015) during the pandemic period. <b><i>Conclusion:</i></b> During the COVID-19 pandemic, Catalonia’s stroke system’s weakest points were the delay to EMS alert and a decline of stroke code activations, reperfusion treatments, and interhospital transfers, mostly at local centers. Patients suffering an acute stroke during the pandemic period had higher odds of poor functional outcome and death. The complete stroke care system’s analysis is crucial to allocate resources appropriately.

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