995 resultados para Stroke volume
Resumo:
BACKGROUND AND PURPOSE: The ASTRAL score was externally validated showing remarkable consistency on 3-month outcome prognosis in patients with acute ischemic stroke. The present study aimed to evaluate ASTRAL score's prognostic accuracy to predict 5-year outcome. METHODS: All consecutive patients with acute ischemic stroke registered in the Athens Stroke Registry between January 1, 1998, and December 31, 2010, were included. Patients were excluded if admitted >24 hours after symptom onset or if any ASTRAL score component was missing. End points were 5-year unfavorable functional outcome, defined as modified Rankin Scale 3 to 6, and 5-year mortality. For each outcome, the area under the receiver operating characteristics curve was calculated; also, a multivariate Cox proportional hazards analysis was performed to investigate whether the ASTRAL score was an independent predictor of outcome. The Kaplan-Meier product limit method was used to estimate the probability of 5-year survival for each ASTRAL score quartile. RESULTS: The area under the receiver operating characteristics curve of the score to predict 5-year unfavorable functional outcome was 0.89, 95% confidence interval 0.88 to 0.91. In multivariate Cox proportional hazards analysis, the ASTRAL score was independently associated with 5-year unfavorable functional outcome (hazard ratio, 1.09; 95% confidence interval, 1.08-1.10). The area under the receiver operating characteristics curve for the ASTRAL score's discriminatory power to predict 5-year mortality was 0.81 (95% confidence interval, 0.78-0.83). In multivariate analysis, the ASTRAL score was independently associated with 5-year mortality (hazard ratio, 1.09, 95% confidence interval, 1.08-1.10). During the 5-year follow-up, the probability of survival was significantly lower with increasing ASTRAL score quartiles (log-rank test <0.001). CONCLUSIONS: The ASTRAL score reliably predicts 5-year functional outcome and mortality in patients with acute ischemic stroke.
Resumo:
PURPOSE: To evaluate accuracy and reproducibility of flow velocity and volume measurements in a phantom and in human coronary arteries using breathhold velocity-encoded (VE) MRI with spiral k-space sampling at 3 Tesla. MATERIALS AND METHODS: Flow velocity assessment was performed using VE MRI with spiral k-space sampling. Accuracy of VE MRI was tested in vitro at five constant flow rates. Reproducibility was investigated in 19 healthy subjects (mean age 25.4 +/- 1.2 years, 11 men) by repeated acquisition in the right coronary artery (RCA). RESULTS: MRI-measured flow rates correlated strongly with volumetric collection (Pearson correlation r = 0.99; P < 0.01). Due to limited sample resolution, VE MRI overestimated the flow rate by 47% on average when nonconstricted region-of-interest segmentation was used. Using constricted region-of-interest segmentation with lumen size equal to ground-truth luminal size, less than 13% error in flow rate was found. In vivo RCA flow velocity assessment was successful in 82% of the applied studies. High interscan, intra- and inter-observer agreement was found for almost all indices describing coronary flow velocity. Reproducibility for repeated acquisitions varied by less than 16% for peak velocity values and by less than 24% for flow volumes. CONCLUSION: 3T breathhold VE MRI with spiral k-space sampling enables accurate and reproducible assessment of RCA flow velocity.
Resumo:
On-street parking has been considered problematic by engineers for many years. In fact, numerous studies have concluded that diagonal or angle parking in particular is potentially more of a safety concern than parallel or no parking at all. It is a common position of many states, including Iowa, to discourage or completely prohibit angle parking on primary road extensions in urban areas. However, with the acceptance of “context sensitive design” and traffic calming techniques, policies for on-street parking are receiving re -consideration in many agencies including the FHWA. This study was undertaken to analyze operational and safety histories in the state of Iowa where various types of on-street parking have existed for many years, concentrating in particular on smaller communities. Specifically of interest was a comparison of diagonal parking locations to other types with regard to related crash histories. If possible, it was intended to develop guidelines to assist Iowa Department of Transportation designers in the consideration of parking requirements for road improvements through small communities. In this regard, several criteria were analyzed to determine possible contribution to crash history including road width, clearance to parked vehicles, traffic volumes, community population, and length of parking area. None of these factors, with the possible exception of population, displayed a clearly definable relationship to crash history. However, when average crash rates for various parking types were compared for non-intersection crashes, differences in rates between areas with diagonal parking and those with parallel parking were almost negligible. In fact, those observed rates were less than sample locations with no parking at all. These results seem to indicate that indeed there may exist no compelling justification for blanket prohibition of angle parking along Iowa’s primary extensions in all urban areas. Rather, a case-by-case investigation with each project design of the most applicable parking type would seem appropriate in smaller communities.
Resumo:
Several superstructure design methodologies have been developed for low volume road bridges by the Iowa State University Bridge Engineering Center. However, to date no standard abutment designs have been developed. Thus, there was a need to establish an easy to use design methodology in addition to generating generic abutment standards and other design aids for the more common substructure systems used in Iowa. The final report for this project consists of three volumes. The first volume (this volume) summarizes the research completed in this project. A survey of the Iowa County Engineers was conducted from which it was determined that while most counties use similar types of abutments, only 17 percent use some type of standard abutment designs or plans. A literature review revealed several possible alternative abutment systems for future use on low volume road bridges in addition to two separate substructure lateral load analysis methods. These consisted of a linear and a non-linear method. The linear analysis method was used for this project due to its relative simplicity and the relative accuracy of the maximum pile moment when compared to values obtained from the more complex non-linear analysis method. The resulting design methodology was developed for single span stub abutments supported on steel or timber piles with a bridge span length ranging from 20 to 90 ft and roadway widths of 24 and 30 ft. However, other roadway widths can be designed using the foundation design template provided. The backwall height is limited to a range of 6 to 12 ft, and the soil type is classified as cohesive or cohesionless. The design methodology was developed using the guidelines specified by the American Association of State Highway Transportation Officials Standard Specifications, the Iowa Department of Transportation Bridge Design Manual, and the National Design Specifications for Wood Construction. The second volume introduces and outlines the use of the various design aids developed for this project. Charts for determining dead and live gravity loads based on the roadway width, span length, and superstructure type are provided. A foundation design template was developed in which the engineer can check a substructure design by inputting basic bridge site information. Tables published by the Iowa Department of Transportation that provide values for estimating pile friction and end bearing for different combinations of soils and pile types are also included. Generic standard abutment plans were developed for which the engineer can provide necessary bridge site information in the spaces provided. These tools enable engineers to design and detail county bridge substructures more efficiently. The third volume provides two sets of calculations that demonstrate the application of the substructure design methodology developed in this project. These calculations also verify the accuracy of the foundation design template. The printouts from the foundation design template are provided at the end of each example. Also several tables provide various foundation details for a pre-cast double tee superstructure with different combinations of soil type, backwall height, and pile type.
Resumo:
Several superstructure design methodologies have been developed for low volume road bridges by the Iowa State University Bridge Engineering Center. However, to date no standard abutment designs have been developed. Thus, there was a need to establish an easy to use design methodology in addition to generating generic abutment standards and other design aids for the more common substructure systems used in Iowa. The final report for this project consists of three volumes. The first volume summarizes the research completed in this project. A survey of the Iowa County Engineers was conducted from which it was determined that while most counties use similar types of abutments, only 17 percent use some type of standard abutment designs or plans. A literature review revealed several possible alternative abutment systems for future use on low volume road bridges in addition to two separate substructure lateral load analysis methods. These consisted of a linear and a non-linear method. The linear analysis method was used for this project due to its relative simplicity and the relative accuracy of the maximum pile moment when compared to values obtained from the more complex non-linear analysis method. The resulting design methodology was developed for single span stub abutments supported on steel or timber piles with a bridge span length ranging from 20 to 90 ft and roadway widths of 24 and 30 ft. However, other roadway widths can be designed using the foundation design template provided. The backwall height is limited to a range of 6 to 12 ft, and the soil type is classified as cohesive or cohesionless. The design methodology was developed using the guidelines specified by the American Association of State Highway Transportation Officials Standard Specifications, the Iowa Department of Transportation Bridge Design Manual, and the National Design Specifications for Wood Construction. The second volume introduces and outlines the use of the various design aids developed for this project. Charts for determining dead and live gravity loads based on the roadway width, span length, and superstructure type are provided. A foundation design template was developed in which the engineer can check a substructure design by inputting basic bridge site information. Tables published by the Iowa Department of Transportation that provide values for estimating pile friction and end bearing for different combinations of soils and pile types are also included. Generic standard abutment plans were developed for which the engineer can provide necessary bridge site information in the spaces provided. These tools enable engineers to design and detail county bridge substructures more efficiently. The third volume (this volume) provides two sets of calculations that demonstrate the application of the substructure design methodology developed in this project. These calculations also verify the accuracy of the foundation design template. The printouts from the foundation design template are provided at the end of each example. Also several tables provide various foundation details for a pre-cast double tee superstructure with different combinations of soil type, backwall height, and pile type.
Resumo:
Several superstructure design methodologies have been developed for low volume road bridges by the Iowa State University Bridge Engineering Center. However, to date no standard abutment designs have been developed. Thus, there was a need to establish an easy to use design methodology in addition to generating generic abutment standards and other design aids for the more common substructure systems used in Iowa. The final report for this project consists of three volumes. The first volume summarizes the research completed in this project. A survey of the Iowa County Engineers was conducted from which it was determined that while most counties use similar types of abutments, only 17 percent use some type of standard abutment designs or plans. A literature review revealed several possible alternative abutment systems for future use on low volume road bridges in addition to two separate substructure lateral load analysis methods. These consisted of a linear and a non-linear method. The linear analysis method was used for this project due to its relative simplicity and the relative accuracy of the maximum pile moment when compared to values obtained from the more complex non-linear analysis method. The resulting design methodology was developed for single span stub abutments supported on steel or timber piles with a bridge span length ranging from 20 to 90 ft and roadway widths of 24 and 30 ft. However, other roadway widths can be designed using the foundation design template provided. The backwall height is limited to a range of 6 to 12 ft, and the soil type is classified as cohesive or cohesionless. The design methodology was developed using the guidelines specified by the American Association of State Highway Transportation Officials Standard Specifications, the Iowa Department of Transportation Bridge Design Manual, and the National Design Specifications for Wood Construction. The second volume (this volume) introduces and outlines the use of the various design aids developed for this project. Charts for determining dead and live gravity loads based on the roadway width, span length, and superstructure type are provided. A foundation design template was developed in which the engineer can check a substructure design by inputting basic bridge site information. Tables published by the Iowa Department of Transportation that provide values for estimating pile friction and end bearing for different combinations of soils and pile types are also included. Generic standard abutment plans were developed for which the engineer can provide necessary bridge site information in the spaces provided. These tools enable engineers to design and detail county bridge substructures more efficiently. The third volume provides two sets of calculations that demonstrate the application of the substructure design methodology developed in this project. These calculations also verify the accuracy of the foundation design template. The printouts from the foundation design template are provided at the end of each example. Also several tables provide various foundation details for a pre-cast double tee superstructure with different combinations of soil type, backwall height, and pile type.
Resumo:
This paper provides an overview on the actual state of acute therapy in patients with ischemic stroke. The discussion focusses on intravenous and intraarterial thrombolysis, antithrombotic therapy, and the treatment of medical and neurological complications, and therapy recommendations are presented. Finally ongoing studies, particularly those concerning thrombolysis with glycoprotein IIb/IIIa receptor blockers and ultrasound-assisted thrombolysis, are presented.
Resumo:
An Iowa State University–led team facilitated development of the CP Road Map. They developed a database of existing research. They gathered input, face to face, from the highway community. They identified gaps in research that became the basis for problem statements, which they organized into a cohesive, strategic research plan.
Resumo:
An Iowa State University–led team facilitated development of the CP Road Map. They developed a database of existing research. They gathered input, face to face, from the highway community. They identified gaps in research that became the basis for problem statements, which they organized into a cohesive, strategic research plan.
Resumo:
Seizures appear at stroke presentation, during the acute phase or as a late complication of stroke. Thrombolysis has not been investigated as a risk factor despite its potential neurotoxic effect. We try to identify risk factors for seizures during the acute phase of ischemic stroke in a cohort including thrombolysed patients. We undertook a case-control study at a single stroke center using data from Acute Stroke Registry and Analyse of Lausanne (ASTRAL). Patients with seizure occurring during the first 7 days following stroke were retrospectively identified. Bi-variable and multivariable statistical analyses were applied to compare cases and randomly selected controls. We identified 28 patients experiencing from seizures in 2,327 acute ischemic strokes (1.2 %). All seizures occurred during the first 72 h. Cortical involvement, thrombolysis with rt-PA, arterial recanalization, and higher initial NIHSS were statistically associated with seizures in univariated analysis. Backward linear regression identified cortical involvement (OR 7.53, 95 % CI 1.6-35.2, p < 0.01) and thrombolysis (OR 4.6, 95 % CI 1.6-13.4, p = 0.01) as being independently associated with seizure occurrence. Overall, 3-month outcome measured by the modified Rankin scale (mRS) was comparable in both groups. In the subgroup of thrombolysed patients, outcome was significantly worse at 3 months in the seizure group with 9/12 (75 %) patients with mRS ≥3, compared to 6/18 (33.3 %) in the seizure-free group (p = 0.03). Acute seizures in acute ischemic stroke were relatively infrequent. Cortical involvement and thrombolysis with rt-PA are the principal risk factors. Seizures have a potential negative influence on clinical outcome in thrombolysed patients.
Resumo:
INTRODUCTION: Poststroke hyperglycemia has been associated with unfavorable outcome. Several trials investigated the use of intravenous insulin to control hyperglycemia in acute stroke. This meta-analysis summarizes all available evidence from randomized controlled trials in order to assess its efficacy and safety. METHODS: We searched PubMed until 15/02/2013 for randomized clinical trials using the following search items: 'intravenous insulin' or 'hyperglycemia', and 'stroke'. Eligible studies had to be randomized controlled trials of intravenous insulin in hyperglycemic patients with acute stroke. Analysis was performed on intention-to-treat basis using the Peto fixed-effects method. The efficacy outcomes were mortality and favorable functional outcome. The safety outcomes were mortality, any hypoglycemia (symptomatic or asymptomatic), and symptomatic hypoglycemia. RESULTS: Among 462 potentially eligible articles, nine studies with 1491 patients were included in the meta-analysis. There was no statistically significant difference in mortality between patients who were treated with intravenous insulin and controls (odds ratio: 1.16, 95% confidence interval: 0.89-1.49). Similarly, the rate of favorable functional outcome was not statistically different (odds ratio: 1.01, 95% confidence interval: 0.81-1.26). The rates of any hypoglycemia (odds ratio: 8.19, 95% confidence interval: 5.60-11.98) and of symptomatic hypoglycemia (odds ratio: 6.15, 95% confidence interval: 1.88-20.15) were higher in patients treated with intravenous insulin. There was no heterogeneity across the included trials in any of the outcomes studied. CONCLUSIONS: This meta-analysis of randomized controlled trials does not support the use of intravenous insulin in hyperglycemic stroke patients to improve mortality or functional outcome. The risk of hypoglycemia is increased, however.