| 1. |
- Abid, Muhammad Adil, et al.
(författare)
-
A Genetic Algorithm for Optimizing Mobile Stroke Unit Deployment
- 2023
-
Ingår i: Procedia Computer Science. - : Elsevier. - 1877-0509. ; 225, s. 3536-3545
-
Tidskriftsartikel (refereegranskat)abstract
- A mobile stroke unit (MSU) is an advanced ambulance equipped with specialized technology and trained healthcare personnel to provide on-site diagnosis and treatment for stroke patients. Providing efficient access to healthcare (in a viable way) requires optimizing the placement of MSUs. In this study, we propose a time-efficient method based on a genetic algorithm (GA) to find the most suitable ambulance sites for the placement of MSUs (given the number of MSUs and a set of potential sites). We designed an efficient encoding scheme for the input data (the number of MSUs and potential sites) and developed custom selection, crossover, and mutation operators that are tailored according to the characteristics of the MSU allocation problem. We present a case study on the Southern Healthcare Region in Sweden to demonstrate the generality and robustness of our proposed GA method. Particularly, we demonstrate our method's flexibility and adaptability through a series of experiments across multiple settings. For the considered scenario, our proposed method outperforms the exhaustive search method by finding the best locations within 0.16, 1.44, and 10.09 minutes in the deployment of three MSUs, four MSUs, and five MSUs, resulting in 8.75x, 16.36x, and 24.77x faster performance, respectively. Furthermore, we validate the method's robustness by iterating GA multiple times and reporting its average fitness score (performance convergence). In addition, we show the effectiveness of our method by evaluating key hyperparameters, that is, population size, mutation rate, and the number of generations.
|
|
| 2. |
- Abul-Kasim, Kasim, et al.
(författare)
-
Added diagnostic utility of CT perfusion and CT angiography in acute ischemic stroke. Evaluation of three different patient categories
- 2009
-
Ingår i: Functional Neurology. - 0393-5264. ; 24:2, s. 93-98
-
Tidskriftsartikel (refereegranskat)abstract
- Patients with a clinical picture of acute ischemic stroke are a heterogeneous group. The aim of this study was to evaluate the added utility of CT perfusion (CTP) and CT angiography (CTA) in the workup of three different categories of acute ischemic stroke patients. Fifty patients (61 +/- 05 years old) were included in this retrospective analysis. Twenty-nine patients had transient ischemic attacks (TIAs) (Group I), 15 were not eligible for treatment with thrombolysis (Group II) and six showed no improvement after thrombolysis (Group III). CTP and CTA provided additional information, not revealed by plain CT, in all the Group II patients and in one third of the patients belonging to the other groups. The final diagnoses were TIA (n=23), thromboembolic cerebral infarctions (n=22), carotid artery dissection (n=4) and metastases (n=1). Of the 29 patients admitted with TIA, only 22 patients still had this diagnosis on discharge from the stroke unit. Given the risk of impending stroke, it would be important to include these modalities in the initial workup of TIA.
|
|
| 3. |
- Abul-Kasim, Kasim, et al.
(författare)
-
Combined Clinical and Radiological Prognostic Model in Acute Ischemic Stroke
- 2010
-
Ingår i: Acta Neurologica Belgica. - 2240-2993. ; 110:3, s. 239-245
-
Tidskriftsartikel (refereegranskat)abstract
- We sought to propose and test the validity of a comprehensive prognostic model in middle cerebral artery-stroke treated with Intravenous thrombolysis. A total of 127 consecutive patients (aged 70 +/- 12 years; 54% males) were included in this retrospective study. Variables included in our prognostic model were: NIHSS on admission (1-3 points), occurrence of hyperdense middle cerebral artery sign and early ischemic signs on baseline CT (1 point each). NIHSS at 24 hours (0-3 points), posttreatment hemorrhage (1 point), and infarct volume (0-4 points). The score range teas 1-13, with higher values suggest unfavorable prognosis. Our prognostic score was correlated with the modified Rankin scale (mRS) at 3 months after stroke [correlation coefficient of 0.62, P < 0.001] and can thus help early prediction of the functional outcome. Logistic regression showed that NIHSS at 24 hours and EICs on baseline CT were independent predictor of our prognostic score (adjusted odds ratio of 4.1 and 5). Adopting a cut-off value of prognostic score <= 3 for favorable prognosis and >= 7 for unfavorable prognosis helped to predict the need for institutionalization and the functional outcome with higher accuracy and predictive values compared with using scores only based on NIHSS.
|
|
| 4. |
- Abul-Kasim, Kasim, et al.
(författare)
-
Hyperdense middle cerebral artery sign in multidetector computed tomography: Definition, occurrence, and reliability analysis.
- 2009
-
Ingår i: Neurology India. - : Medknow. - 0028-3886. ; 57:2, s. 143-150
-
Tidskriftsartikel (refereegranskat)abstract
- Background: The hyperdense middle cerebral artery sign (HMCAS) is one of the early changes seen on the computed tomography in acute ischemic stroke of MCA territory. Aims: To evaluate the reliability of subjective evaluation of HMCAS on CT performed at multidetector CT (MDCT) and evaluated in the Picture Archiving Communication Systems, to define objective criteria for HMCAS and to find out if there are any predictors for the occurrence of HMCAS. Materials and Methods: CTs of 121 consecutive patients (mean age of 70 years) treated with thrombolytic therapy were retrospectively evaluated by two neuroradiologists both subjectively and objectively with respect to HMCAS. Results: HMCAS was subjectively found in 32% of study population. The interobserver and intraobserver agreement were substantial (K value of 0.69 and 0.80, respectively) and increased to almost perfect (Kvalue of 0.86) when the reader provided with clinical information. The HMCAS was found twice as often in male patients. Patients with HMCAS were three years younger than those whose baseline CT did not show HMCAS. A 100% sensitivity achieved when objective criteria were defined as combination of MCA attenuation >/= 46HU and MCA ratio > 1.2 (using oval ROIs) and MCA attenuation >/= 50 HU and MCA ratio of > 1.4 (using pixel sized ROIs). Conclusion: Performing CT examinations on MDCT and assessment of the images in PACS might have contributed to improvement of the reliability of evaluating HMCAS on CT by enabling an objective evaluation of this sign with measurements of attenuation value in the course of MCA using oval or pixel sized ROIs as well as estimation of MCA ratio .
|
|
| 5. |
- Abul-Kasim, Kasim, et al.
(författare)
-
Hyperdense middle cerebral artery sign is an ominous prognostic marker despite optimal workflow.
- 2010
-
Ingår i: Acta Neurologica Scandinavica. - : Hindawi Limited. - 1600-0404 .- 0001-6314. ; 122, s. 132-139
-
Tidskriftsartikel (refereegranskat)abstract
- Abul-Kasim K, Brizzi M, Petersson J. Hyperdense middle cerebral artery sign is an ominous prognostic marker despite optimal workflow. Acta Neurol Scand: DOI: 10.1111/j.1600-0404.2009.01277.x. (c) 2009 The Authors Journal compilation (c) 2009 Blackwell Munksgaard.Objectives - To evaluate the association between the hyperdense middle cerebral artery sign (HMCAS) and the functional outcome on one hand, and different predictors such as the National Institutes of Health Stroke Scale (NIHSS), infarct size, ASPECTS Score, intracerebral hemorrhage, and mortality on the other hand. Material and methods - Retrospective analysis of 120 patients with MCA-stroke treated with intravenous thrombolysis. We tested the association between HMCAS and NIHSS, infarct volume, ASPECTS, outcome, level of consciousness, different recorded time intervals, and the day/time of admission. Results - Seventy-four percentage of patients treated with thrombolysis developed cerebral infarction. All patients with HMCAS (n = 39) sustained infarction and only 31% showed favorable outcome compared with 62% and 60%, respectively among patients without HMCAS (P < 0.001 and P = 0.002). There was statistically significant association between functional outcome and HMCAS (P = 0.002), infarct volume, NIHSS, and ASPECTS (P < 0.001). The time to treatment was 12 min shorter in patients who developed infarction (P = 0.037). Independent predictors for outcome were NIHSS and the occurrence of cerebral infarction on computed tomography for the whole study population, and infarct volume for patients who sustained cerebral infarction. Conclusions - Despite optimal workflow, patients with HMCAS showed poor outcome after intravenous thrombolysis. The results emphasize the urgent need for more effective revascularization therapies and neuroprotective treatment in this subgroup of stroke patients.
|
|
| 6. |
- Al Fatah, Jabir, et al.
(författare)
-
An agent-based simulation model for assessment of prehospital triage policies concerning destination of stroke patients
- 2018
-
Ingår i: Procedia Computer Science. - : Elsevier. - 1877-0509. ; 141, s. 405-412
-
Tidskriftsartikel (refereegranskat)abstract
- Stroke is a life threatening medical condition that is caused either by a blood clot or a bleeding inside the brain. It is generally agreed that immediate treatment of stroke patients is crucial for their ability to recover; however, before treatment can be initiated, the stroke patient has to be diagnosed using, for example, a computed tomography scan of the brain. This, in turn, requires that the patient is transported to a hospital for diagnosis, which is a procedure that consumes valuable time and resources. In the current paper, we present an agent-based simulation model for assessment of logistical stroke patient triage policies. Using a population of stroke patients as input, the model enables to simulate the activities and the main decisions involved in the logistical operations of stroke patients. In an experimental study covering the southernmost part of Sweden, we used the simulation model in order to assess two different policies regarding where to send patients for diagnosis; the nearest hospital policy and the nearest hospital towards the stroke center policy. Our simulation results show that the patients in need of special treatment favor from being transported in direction towards the stroke center, whereas the patients who are not in need of specialist treatment favor from being sent to the closest hospital.
|
|
| 7. |
- Amouzad Mahdiraji, Saeid, et al.
(författare)
-
A Framework for Constructing Discrete Event Simulation Models for Emergency Medical Service Policy Analysis
- 2022
-
Ingår i: Procedia Computer Science. - : Elsevier BV. - 1877-0509. ; 210, s. 133-140
-
Konferensbidrag (refereegranskat)abstract
- Constructing simulation models can be a complex and time-consuming task, in particular if the models are constructed from scratch or if a general-purpose simulation modeling tool is used. In this paper, we propose a model construction framework, which aims to simplify the process of constructing discrete event simulation models for emergency medical service (EMS) policy analysis. The main building blocks used in the framework are a set of general activities that can be used to represent different EMS care chains modeled as flowcharts. The framework allows to build models only by specifying input data, including demographic and statistical data, and providing a care chain of activities and decisions. In a case study, we evaluated the framework by using it to construct a model for the simulation of the EMS activities related to acute stroke. Our evaluation shows that the predefined activities included in the framework are sufficient to build a simulation model for the rather complex case of acute stroke.
|
|
| 8. |
- Amouzad Mahdiraji, Saeid, et al.
(författare)
-
A Micro-Level Simulation Model for Analyzing the Use of MSUs in Southern Sweden
- 2021
-
Ingår i: Procedia Computer Science : 12th International Conference on Emerging Ubiquitous Systems and Pervasive Networks, EUSPN 2021 / 11th International Conference on Current and Future Trends of Information and Communication Technologies in Healthcare, ICTH 2021 - 12th International Conference on Emerging Ubiquitous Systems and Pervasive Networks, EUSPN 2021 / 11th International Conference on Current and Future Trends of Information and Communication Technologies in Healthcare, ICTH 2021. - : Elsevier BV. ; 198, s. 132-139
-
Konferensbidrag (refereegranskat)abstract
- A mobile stroke unit (MSU) is a special type of ambulance, where stroke patients can be diagnosed and provided intravenous treatment, hence allowing to cut down the time to treatment for stroke patients. We present a discrete event simulation (DES) model to study the potential benefits of using MSUs in the southern health care region of Sweden (SHR). We included the activities and actions used in the SHR for stroke patient transportation as events in the DES model, and we generated a synthetic set of stroke patients as input for the simulation model. In a scenario study, we compared two scenarios, including three MSUs each, with the current situation, having only regular ambulances. We also performed a sensitivity analysis to further evaluate the presented DES model. For both MSU scenarios, our simulation results indicate that the average time to treatment is expected to decrease for the whole region and for each municipality of SHR. For example, the average time to treatment in the SHR is reduced from 1.31h in the baseline scenario to 1.20h and 1.23h for the two MSU scenarios. In addition, the share of stroke patients who are expected to receive treatment within one hour is increased by a factor of about 3 for both MSU scenarios.
|
|
| 9. |
- Amouzad Mahdiraji, Saeid, et al.
(författare)
-
An Optimization Model for the Placement of Mobile Stroke Units
- 2024
-
Ingår i: Advanced Research in Technologies, Information, Innovation and Sustainability - 3rd International Conference, ARTIIS 2023, Proceedings. - : Springer. - 1865-0937 .- 1865-0929. - 9783031488573 - 9783031488580 ; 1935 CCIS, s. 297-310
-
Konferensbidrag (refereegranskat)abstract
- Mobile Stroke Units (MSUs) are specialized ambulances that can diagnose and treat stroke patients; hence, reducing the time to treatment for stroke patients. Optimal placement of MSUs in a geographic region enables to maximize access to treatment for stroke patients. We contribute a mathematical model to optimally place MSUs in a geographic region. The objective function of the model takes the tradeoff perspective, balancing between the efficiency and equity perspectives for the MSU placement. Solving the optimization problem enables to optimize the placement of MSUs for the chosen tradeoff between the efficiency and equity perspectives. We applied the model to the Blekinge and Kronoberg counties of Sweden to illustrate the applicability of our model. The experimental findings show both the correctness of the suggested model and the benefits of placing MSUs in the considered regions.
|
|
| 10. |
- Amouzad Mahdiraji, Saeid
(författare)
-
On the Use of Simulation and Optimization for the Analysis and Planning of Prehospital Stroke Care
- 2022
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Immediate treatment is of extreme importance for stroke patients. However, providing fast enough treatment for stroke patients is far from trivial, mainly due to logistical challenges and difficulties in diagnosing the correct stroke type. One way to reduce the time to treatment is to use so-called Mobile Stroke Units (MSUs), which allows to diagnose and provide treatment for stroke patients already at the patient scene. A well-designed stroke transport policy is vital to improve the access to treatment for stroke patients. Simulation and mathematical optimization are useful approaches for assessing and optimizing stroke transport policies, without endangering the health of the patients.The main purpose of this thesis is to contribute to improving the situation for stroke patients and to reducing the social impacts of stroke. The aim is to study how to use simulation and optimization to achieve improved analysis and planning of prehospital stroke care. In particular, we focus on assessing the potential use of MSUs in a geographic area. In this thesis, optimization is used to identify the optimal locations of MSUs, and simulation is used to assess different stroke transport policies, including MSU locations. The results of this thesis aim to support public health authorities when making decisions in the prehospital stroke care domain.In order to fulfill the aim of this thesis, we develop and analyze a number of different simulation and optimization models. First, we propose a macro-level simulation model, an average time to treatment estimation model, used to estimate the expected time to treatment for different parts of a geographic region. Using the proposed model, we generate two different MSU scenarios to explore the potential benefits of employing MSUs in Sweden’s southern healthcare region (SHR). Second, we present an optimization model to identify the best placement of MSUs while making a trade-off between the efficiency and equity perspectives, providing maximum population coverage and equal service for all patients, respectively. The trade-off function used in the model makes use of the concepts of weighted average time to treatment to model efficiency and the time difference between the expected time to treatment for different geographical areas to model equity. In a scenario study applied in the SHR, we evaluate our optimization model by comparing the current situation with three MSU scenarios, including 1, 2, and 3 MSUs.Third, we present a micro-level discrete event simulation model to assess stroke transport policies, including MSUs, allowing us to model the behaviors of individual entities, such as patients and emergency vehicles, over time. We generate a synthetic set of stroke patients using a Poisson distribution, used as input in a scenario study.Finally, we present a modeling framework with reusable components, which aims to facilitate the construction of discrete event simulation models in the emergency medical services domain. The framework consists of a number of generic activities, which can be used to represent healthcare chains modeled in the form of flowcharts. As the framework includes activities and policies modeled on the general level, the framework can be used to create models only by providing input data and a care chain specification. We evaluate the framework by using it to build a model for simulating EMS activities related to the complex case of acute stroke.
|
|
